Model Airplane FAQ v1.15

Gerrit Hiddink

This is the Frequently Asked Questions (FAQ) list, with answers of course, for model airplanes. The questions and their answers were taken from the newsgroups rec.models.rc.air and rec.models.rc.soaring, while some information was also `kannabilized' from the Murray Lane FAQ. This FAQ was last updated in october 1998, so it does not seem to be maintained anymore. I've therefor taken the liberty to merge it with my FAQ.
This FAQ is organized in sections and subsections. The subsections contain questions, with one or more answers. The original author of the answer is indicated in the header of each answer. If the answers are really fragmented, then I'll take the editorial freedom to create one consistent answer.
You can find an index of all questions here: allq.html.
I hope this FAQ brings you the answers to many questions, so that you will be able to fly happily ever after. So here goes!


SECTION 1:Designing and understanding airplanes

Subsection: Airplanes in general


Question: What is the difference between a sailplane and a glider?

Answer by Brett Jaffee
Gliders are planes that glide down to earth without power. A good example might be a WW2 troop glider. It's not designed to catch or ride thermals and climb, just to be released from its tow plane and glide down to earth. The space shuttle in its landing mode would be another example.
A sailplane, OTOH, is designed to ride the wind and climb in the thermals and other updrafts. In truth, just about any plane, even powered ones, can climb in thermals and updrafts if they are strong enuf, but "sailplane" is usually reserved for planes that are purpose-built to take advantage of this.

Subsection: Wings


Question: What is the 'chord' of a wing?

Answer by David Larkin
The chord is the distance between the front of the wing (the leading edge) and the back (the trailing edge).

Answer by Bernard Grosperrin
measured on a line parallel to the fuselage..... and obviously a chord is not a constant, it's just a value for a given point on the wing. Root cord and tip chord can be quite different...

Question: What is 'Wing Incidence' and 'Wing Decalage' ?

Answer by Jonathan Gogan
Imagine a line down the middle of the fuselage - this is called the water line (because planes usedto be made by shipwrights - you live and learn) Put the wing at an angle of about + 2.5 degrees to this; this is the riggers angle, also called angle of incidence. When the wind flows across the wing, relative to the chord line (a line across the centre of the wing from leading edge to trailing edge) it defines the angle of attack. this changes all the time - if it gets too large (greater than 15 to 18 degress) you stall. The tail (horizontal stabiliser) is also at a small +ve angle compared to the water line but not as great as the riggers angle! the difference in the two angles, i.e. 2.5 for the wing and 1.5 for the tail, is known as the decallage.

Question: What is 'fluttering'?

Answer by Robert Barkus
Flutter is where a control surface moves back and forth rapidly without any actual input from the pilot. It is caused by any one of several factors. The two most common are, 1) loose control linkages 2) excessive speed (for a given model/setup). The first is easy to spot. Turn your tx/rx on. Move each surface by hand back and forth. The servo should hold fairly well. If you can move the surface without moving the servo you have too much slop. Flutter will happen very fast (not always) and can quickly break parts like the stab and fin.

Answer by Phil Godwin
The event is a high frequency oscillation of the surface which can sometimes be seen as a blur of the surface in a close flyby and can usually be heard above the sound of the engine. If you hear an unusual buzzing sound and there are no bees in the vicinity then throttle back and land as soon as possible and check your plane over. Look for any loosness or flexibility in the control linkages, hinges broken or worn, or excessive torsional flexibility. The cure can be as simple as adding additional hinges, using larger, stiffer pushrods, eliminating clevis to control horn slop, etc. Or it may require the rebuild of a surface or adding counterbalances. Overpowering a plane can also cause you grief.

Question: What is the effect of increasing the thickness of an airfoil?

Answer by Dr1Driver
It will increase lift and drag, which will make the plane fly slower with the same engine power. If this is what you want, you might want to consider a large diameter/low pitch prop. Say a 10-4 or 11-4 instead of a 10-6.

Question: How do I remove an unwanted warp in my wings?

Answer by Arizona Chuck
When you have a warped wing you can't straighten it on a flat surface. If you have a 1/2" warp you have to block it up so you have a 1/2" warp in the opposite direction, then when it dries it will pop back to straight.

Answer by James G. Branaum
I have sprayed the entire wing with water and weighted it down for a few days. Got to have a straight, flat surface, and two long hard surface items to put on top of the spar and support the weight and another long hard item to put on the T.E. that also will be able to support lots of weight.
Spray the wing down, block the spar in place and weight it, then block and weight the T.E. in place. Try to get the T.E. flat (or all the standoffs anchored to the table with weight) to prevent warping as the wing dries.

Answer by Edwin Smith
If weights and wetting didnt help over night, I would take the sheeting off and do it over if its that bad. Better to sacrifice a sheet of balsa than to risk a bad job. If its glued in really good, I would hack it out with the scalple then use a dremil and various bits to remove the rest.

Answer by Gerrit Hiddink
If you've used a heat-shrinking cover, like Oracover, you can easily remove warps by fixing the wing in the desired (warped if necessary) position, and re-heat the cover. If the effect is not sufficient, then try to warp it a bit more in the reverse direction. Be careful not to overdo the "anti-warp"! Also, only do this if the other methods didn't work because you will keep a certain tension in your wing between the balsa and the cover. This tension may reduce the strength of your wing.

Question: What would the typical thickness be for ribs?

Answer by Dr1Driver
For a 2 meter glider, I'll go with 1/16" (1.5 mm, GH) unless you're planning to winch it, then I might go 3/32" (4.5 mm, GH) on the inner 1/3 of the ribs.

Answer by Gareth Bannister
on my great planes spirit, it has 1/16" ribs (1.5 mm, GH). The wingspan is 78" which I believe is classed as a 2m.

Subsection: Fuselage


Subsection: Tailplane


Question: Does the tailplane area need to be a fixed percentage of the wing area?

Answer by Chas L.
Both Andy Lennon (Model Airplane News, Nov. 96) and Paul Denson (R/C Modeler, Nov. 95) recommend that the stab area be approximately 20% of the wing area.

Subsection: Fuel Engines


Question: What's the nitromethane for in fuel?

Answer by Pé Reivers
Nitromethane does two things
1) It contains oxygen in chemical storage, which can be liberated when heated. This extra oxygen then can be used to burn extra fuel and thus increase power. There is a need however to reduce compression ratio in the engine when using much nitro (>15%)
2) Nitro in itself has low caloric values, but it has a very wide combustion range when mixed with air. (1/1 to 1/5 by weight). Because of this wide range, engines with a lot of nitro mixed in their fuel are less sensitive to changes in fuel supply is in vertical manoeuvres and idle, so with less nitro, you need to be more expert to tune the engine right.

Question: What are the chemical components of diesel fuel?

Answer by David Larkin
The basic formula is equal parts ether, castor oil and kerosene plus 2% Amyl Nitrate or Isopropyl Nitrate (IPN) ignition improver. Depending on the engine, you can vary this. Stick to the above formula for a vintage diesel. But with a modern diesel like the Irvine 40D or 20D you can drop the oil content to as low as 20%. Take the ether content up to 35%, add the ignition improver and the balance is kerosene. Basically you reduce the oil content as you add the following feature in an engine: Single Ball bearing, Twin ball bearing ABC piston/cylinder assembly.
Some people use automotive starting fluid instead of ether. It doesn't contain 100% ether so increase the amount of it and use less kerosene.
It is possible to use old fashioned automotive mineral oil instead of castor oil. Say SAE 40. But generally, castor is preferred.
Commercial model diesel fuels can be obtained from Aerodyne, FHS (Red Max), Eric Clutton and Davis Diesel.

Question: And what's in normal fuel, then?

Answer by Joe L.
The major constituent of model airplane fuel is methanol (methyl alcohol). So a typical RC fuel might be 70% Methanol, 20% oil (synthetic or castor oil, or a combination of both), and 10% nitromethane. If 0% nitromethane then you would have 80% methanol with 20% oil. (These are volume percentages, not weight!, GH)

Subsection: Ducted fans


Question: Do ducted fan motors have gearing?

Answer by Daniel Armstrong
Almost always, belt driven fans where tried but it is generally agreed that there is an aerodynamic advantage having the motor in the duct to reduce the cros-sectional area.

Subsection: Propellors


Question: How to balance a (pre-built) propellor?

Answer by Dno1939
I wouldn't sand it at all! Try spraying the light blade with polyurethane or laquer wood finish. I have used both, and haven't had any problem with fuel attacking the finish. Alternately you could paint the tips with paint so that they are eaiser to see when turning. Just put more paint on the light blade.

Answer by Jack
When it is close to balance (by the way I use Master Air Screw) I add white paint to the tip of the light end. That helps me balance and gives me the visual white when the prop is running.

Question: How much kg or pounds can an engine of a particular volume carry?

Answer by Bob Leserve
Go to, it has a thrust calculator. Read the manual 's thrust section for the approximate value of the weight an engine can carry.

Question: What propellor should I use with what motor?

Answer by Gerrit Hiddink
Here's a table from a German postorder company `Conrad':
Motor (in) Motor (ccm) propellor (in) propellor (cm)
0.5 6x3 15x7
1.0 6x3/6x4 15x7/15x10
1.5 7x4 18x10
.15 2.5 7x6/8x4/9x4 18x15/20x10/23x10
.21 3.5 8x4/8x6/9x4 20x10/20x15/23x10
.25 4.0 9x4/9x6 23x10/23x15
.34 5.5 9x5/9x6 23x13/23x15
.40 6.5 9x6/10x5/10x6 23x15/25x13/25x15
.45 7.5 9x6/10x5/10x6/10x7 23x15/25x13/25x15/25x19
.51 8.3 10x8/11x6 25x20/28x15
.61 10 11x7/11x7.5 28x19
.75 12 12x6/12x8/13x6 30x15/30x20/33x15
.90 15 12x8/13x6 30x20/33x15
1.5 25 18x6/18x8 45x15/45x20
1.8 30 18x8 - 20x8 45x20 - 50x20
2.7 45 20x10 - 22x8 50x25 - 55x20
3.6 60 22x10 - 24x8 55x25 - 60x20

Subsection: Electric Motors


Question: What is the `flux ring' on my electric motor?

Answer by Gerrit Hiddink
This is also known as a `stator ring'. It modifies the magnetic fields of the permanent magnets in the motor, giving it more power (it'll also consume more current from your battery pack).

Subsection: Centre of Gravity


Question: Where should the Centre of Gravity be on my airplane?

Answer by Paul J. Burke
If the wing is constant chord.. the c.g. for safe flight will be at 25% of the chord. For more exhuberant flying, 30% will work...

Answer by David Larkin
If you are an unexperienced flyer, I suggest that you start by balancing the plane so that it balances a quarter of the way back from the front of the wing. Later you can balance it somewhat more towards 30% but as you do so the plane will become more sensitive to elevator movement and may eventually become unstable if you go too far.

Answer by Ezas
Here is just the thing you need. It is very typical for plans to give a VERY conservative C of G setting.
This link will let you calculate the distance from the leading edge at a given % of chord length.

Answer by
I would consider using the Panknin Wing twist formula available from the B2 Streamlines web page. Generally, you will enter parameters relating to the geometry of your swept wing aircraft on the left side of the spreadsheet and the computed parameters (including suggested CG) will be on the right side of the spreadsheet. I have found this formula to be the best predictor of proper CG on a tail less aircraft but CG is somewhat a matter of taste depending on the stability margin you want to fly with on your aircraft (beginners sometimes opt for greater stability and experts generally like "hands off" approximately neutral stability. The "stability factor" entry on the spreadsheet generally has a value from .02 to .04 with .035 about right for most purposes as an initial trim position.

Question: How about the CoG of forward swept wings?

Answer by Ezas
The calculators mentioned in the question above do work if you put in a negative number for sweep.

Question: How do I know the CG is at the correct spot?

Answer by Andrus Kangro
You can do a "dive test". That means - you set as much up trim as it takes, while still flying smoothly. Then you make it dive at 10..15 degrees or so and then return your sticks to normal position. If it levels itselt in 2..5 seconds, then you have CG where it should be. If it makes it faster, then it's too nose heavy and you should remove some weight. If it does not level itself so fast or dives even more, then you should add some weight.

Question: Do I have to check the CG with or without gas?

Answer by Kjell Aanvik & CDance7412
The fuel tank is normally located in front of the CG. A full tank will then move the CG forward, an empty tank will move it rearwards. If you balance your plane with a full tank, you're in for a suprise when flying and emptying the tank.
You must balance the plane with an empty. You want the CG to be correct when landing which will presumably be with the tank mostly empty.

Question: What differences in behavior does the plane exhibit when moving the CG?

Answer by Paul Wetherill
Moving your CG back will not decrease your sink rate. It will however, make your model more sensitve in pitch. You can fly slower and the model will send you a clear message when it contacts lift. Move it too far back and you are likely to experience a "tuck under". Remember to adjust you declage if you move your CG otherwise you will lose efficiency.

Subsection: Radios, receivers and servos


Question: What is PPM and PCM?

Answer by Michael Neverdosky
PPM (Pulse Position Modulation) has the information in the length of space between pulses sent by the transmitter. The length of space varies with the position of the stick on the transmitter and is decoded into a PWM (pluse width modulation) signal to drive the servo. The information is in analog form all the way.
PCM (Pulse Coded Modulation) sends a digital word that has the information to be decoded by the computer in the receiver. The information is in digital (binary number) form during transmission and reception and is usually decoded to PWM to drive standard servos by the receiver.

Question: Well, which one is better then: PPM or PCM?

Answer by Gerrit Hiddink
Don't ask this question at the newsgroups ;)
There are a number of often-heard propositions that may or may not be true: PCM is said to have a larger range, some claim about twice as large.PCM is said to be less sensitive to interference of other transmitters on the same frequency.PCM has failsafe devices, which mean that your servos can enter in a preconfigured position when the TX signal is absent (i.e. idle throttle, a bit rudder/aileron, a bit down elevator)PCM is said to lock out the plane for 2, 5 or 10 seconds when even a very small glitch occurs (1/8 sec)PCM is said to mask glitches so that you will never find onboard control problems, until it is too late... (you could install a glitch counter)

Question: Huh? what is FM and AM then?

Answer by Gerrit Hiddink
They're both techniques to modulate a low frequency signal (LF) onto a high frequency (HF, eg. 35 MHz) carrier signal. Frequency Modulation, or FM, creates very small deviations in the frequency of the HF carrier. Amplitude Modulation, or AM, creates very small deviations in the amplitude (signal strength) of the HF carrier.

Question: What signals go from a receiver to a servo?

Answer by Cliff Griffin
The servos are supposed to get a block-shaped pulse with a fixed frequency, with the duty cycle varying to control the position. A 1-2ms pulse every 20ms (which corresponds to 50 Hz) will give you full travel, with 1.5ms being in the center, 1ms at one extreme and 2ms at the other.

Question: So how does this pulse make the servo move?

Answer by Gerrit Hiddink
A servo works using a feedback loop. This goes as follows: the IC's in the servo translate the pulse width into a voltage, probably using a capacitor: the longer the pulse, the higher the voltage (there's more time and energy to charge the capacitor, so that its charge will get higher).
Then there's a potentiometer connected to the axe of the servo. This This potentiometer consists of a grafite strip and a piece of metal that glides over it. The more the servo turns, the more the metal glider moves towards one side of the strip. If the servo turns the other way, then the glider moves to the other end of the strip. One end of the strip is connected to the 0 volt power lead, the other is connected to the 6v (or whatever) power lead. The wire connected to the metal gliders gives a voltage of 0 volt if the glider is at the 0 volt end, it will give 6 volt if the glider is at the 6 volt end, and it will give anything in between (linearly if it's a linear potentiometer) if it's anywhere in between.
The voltage of the pulse width to voltage circuit and the voltage of the potentiometer are then compared. If the pulse width circuit gives a low voltage, say 1 volt, and the potentiometer is in a position where it gives 5 volts, then the motor is switched on so that the glider of the potentiometer moves towards the 0 volt side. The circuitry inside the servo keeps monitoring both voltages, and will keep the motor running until both voltages are the same. The potentiometer (and the servo's arm) are now in a position that represents 1 volt, which is almost in the utmost position.
If the stick is moved to the center, then the pulse width gets larger, the voltage on the capacitor also gets larger, say 3 volts, and the circuitry that compares the voltages sees that now the voltage of the capacitor is larger than the voltage of the potentiometer, so that the circuitry will turn on the motor to run into the other direction. The potentiometer will then move towards the middle, until it is at the 3 volts position, after which the motor will be turned off.

Question: I heard that the lenght of an antenna is important and should not be modified, why?

Answer by Gerrit Hiddink
The antenna is designed to pick up radio waves. So first let's translate the frequency of a radio set into a wavelength. This is done with the formula: l = s / f with l the length in meters, s the speed of radiowaves through air (which is approximately the speed of light, which is 300.000 km/sec) and f the frequency in Herz. So a set with a frequency of 27 MHz transmits waves of 300.000.000 / 27.000.000 = 11.11 meters. An antenna needs to be either a full wavelength, or a half wavelength with groundplate. Such wires would be way too long. So your receiver pack includes coils, which may be seen as rolled-up antenna, to artificially reduce the needed length of actual wire. So, the length of the actual wire plus the coils in the receiver pack matches the frequency of the set. To know what length the coils in the receiver pack match, you would have to reverse-engineer it. Other than that, or measuring the length of an identical receiver, there's no way to know what length of wire needs to be with a particular receiver. So it may be wise to measure it before you lose some length...

Question: How can I reverse my servo?

Answer by Dick Pettit
You can reverse a servo quite easily, if you have expertise in soldering. Use a small iron, maybe 15-20 watts with a very fine point, and use rosin core solder only. Get help from someone who has experience.
Open the servo and reverse the 2 wires going to the motor. If the motor is connected directly to the PC board, close the servo up and buy a reverser.
You also have to swap the 2 outside wired on the potentiometer, which is WAAAAY down inside the servo case. There are 3 wires, just reverse the outer 2. If you don't feel comfortable doing this, buy a reverser.
If you completed the 2 wire mods, take your soldering iron and etch a big "R" into the case. This'll remind you that this servo is reversed.

Answer by Kirsch
You buy a servo reversing harness, which is just a short extension with a small bit of electronics that reverses the signal to the servo. Simply reversing polarity is a bad thing, or so I've been told.

Subsection: Batteries


Question: What is a battery pack?

Answer by Murray Lane
NiCad battery packs are made up of individual NiCad cells. Each cell generates a voltage of 1.1 volts to 1.5 volts depending on charge and other factors. The pack voltage is simply the sum of the cell voltages. The capacity(C) of each cell depends on the size and formulation of the cell. Normally we use AA (or, perhaps more often, sub-C, GH) size cells which have a capacity of 500 to 900 milli-amp-hours (mAh). All the cells in a pack MUST have the same capacity. The capacity of the pack is the same as that for an individual cell.

Question: What do all these numerics and symbols on NiCD batteries mean?

Answer by Red Scholefield
The numbers obviously translate into mAh's, e.g. a "KR-1200AAE" is a 1200 mAh cell.
From the Sanyo Nickel Cadmium Data Book (98.8. 5.000)
High Cpacity Batteries - E-series/U series
Fast Charge Batteries - R-Series
High Temperature Batteries (Standby use) - H-series
Heat Resistant Batteries (cyclic use) - K-series
Extend Service Life Batteries - C-series
Memory-backup Batteries - S-series
Standard Charge (N-series): N-270AA, N-500A, N-600AA, N-1000SC
Standard Charge (KR-series): KR-1300SC, KR-1500SC
High Capacity (E-series/U-series): KR-600AE, KR-800AE, KR-1000AAU, KR-1100AAU, KR-1200AAE, KR1200AUL, KR-1500AUL, KR-1400AE, KR-1700AU, KR-1700AE, KR-1700SCE, KR-2300SCE
Fast Charge Batteries (R-series): N-500AR, N-1000SCR, N-1250SCRL, N-1300SCR, N-1700SCR, N-1900SCR
Extended Service Life Batteries (C-Series (Note: Specs for these cells are nearly identical with N-series with the exception that they have slightly higer internal resistance, suggesting that a different (longer life) separator may be employed): N-250AAAC, N-270AAC, N-500AC, N-600AAC, N-700AAC, N-600AACL, N-700AACL
The cell diameters as see as AAA, AA, A and SC in the above designations. Cell lenths vary with capacity. The others (H/K/C/S) series are not generally suited for our application).
Sanyo date codes: fist character, year W=92, X=93, Y=94, Z=95, A=96, B=97, C=98, D=99 and so on. second character = month A=Jan, B=Feb, C=Mar..... L=Dec
ZF=95 June
Cells manufactured on Dec 7th, 1999 will carry the date code DL

Question: Do I get more runtime when I add cells, e.g. using 8 instead of 7?

Answer by Cliff Griffin
The 8 cell pack will give your more power at full throttle, and if held at full throttle for the same amount of time, then less run time. At full throttle, 8 cell packs run a higher current, and therefore run down faster if you run them at full throttle. If, however, you use a lot of throttle management, and reserve WOT for rare situation, then it will last just as long, maybe even longer, than a 7 cell pack.

Question: When it's cold, my batteries last shorter. How come?

Answer by Robert Suding
Your NiCad batteries are rated at room temperatures, 68 degrees. At 20 degrees I found that I had lost 20% of their capacity. For example, a 1000 mah pack at 20 degrees F measured 800 mah cycling on my Ultimate Charger. In terms of flights, If you take 5 flights in the Spring & Fall, take 4 flights in the Winter.

Question: What is the capacity of alkaline batteries?

Answer by Red Schonefield
The capacity delivery of alkaline cells is discharge dependent.
You can get all the details for alkline performance including capacity delivery at different loads at:
For openers however you are looking at the following capacities. Note, these are to a cut off voltage of 0.8 volts/cell.
Cell type Capacity Discharge current
AAA 1150 mAh 12 mA
AA 2850 mAh 28 mA
C 7800 mAh 60 mA
D 15000 mAh 115 mA

Question: What is the black corrosion often found in a black wire (Black Wire Syndrom)?

Answer by Red Schonefield
It is a product of the reaction of KOH (Potassium Hydroxide, GH) with the wire (cuprichydroxide Cu(OH)2 - dark blue crystals (note the blue stuff formed in connectors associated with black wire problem), insoluble in water. The KOH is actually driven by the potential across the wire. you can duplicate the effect by immersing a length of lamp cord in a 30% solution of KOH and connecting a voltage source at the other end. Use another identical piece of wire with no voltage source. You will note that the KOH creeps along one wire only, not equally along the other three.
This is why you must remove exhausted batteries from your transmitter and receiver.

Question: Where can I learn more about batteries?

Answer by Gerrit Hiddink
You can find a battery tutorial here: or alternatively you can find a FAQ here:

Subsection: Electronics


Question: What is an OPTO thingy in a speed controller?

Answer by Spadman
Without getting into a highly detailed description it is used to eliminate noise transferance while providing control over current. This is achieved by eliminating the hard wire electrical connection inside the controller and replacing it with a opto coupler. The sitching is then done by controlling a photo diode with a LED emitter (sort of like a light activated switch). This eliminates most possibility of electrical noise. Most comonly refered to as "opto isolation" It is found in better circuits and extensively used throughout the electronics industry in general. --

SECTION 2:Building Airplanes

Subsection: Plans


Question: Where can I obtain free plans?

Answer by Gerrit Hiddink
Look at the following urls: for 1/12 scale combat planes; for the famous StarCad plans repository; for some simple plans; the Balsadust homepage Thomas Delgatto's plans

Question: How can I print .dxf files?

Answer by Gerrit Hiddink
You can use a number of CAD tools to print .dxf files. The program has to be able to print a large drawing onto a number of A4 sheets if you do not have an A0 printer or plotter. The program I use is IMSI TurboCAD 2D, available for free at

Question: What tools are available to draw plans myself?

Question: How can I transfer a plan to wood?

Answer by Spadman
You can xerox (parts of) the plans and put them face-down on the wood. Then iron the paper so that the drawing is transferred to the wood. Aside from the fact that they are a mirror copy, there will be a slight size difference. I overcome this by copying the original at 99% or making sure that I always cut to the inside of the line. Of course when doing large pieces like a fuse side this won't help much, but for most sport planes the size difference is of little concern. You can check with a ruler if the size hasn't been changed.
Another old favorite method is to tape the plan to a window and then a piece of tracing paper to the plan. Light coming through the plan will allow you to make really good tracings of the big pieces, for the stick and cut method of duplicating parts. Just make sure it's not night.

Answer by Lars Steffenrem
I use to glue the photocopy directly to the balsa/plywood using a gluestick. It usually comes off quite easy, and if not, soften the paper with a damp rag and scrape it off.

Subsection: Scaling questions


Question: What happens to the thicknesses of wood when enlarging plans from .40 to 1/4 scale?

Answer (author unknown)
It's not necessarily linear. It's more of a judgement call. For example, if the 40 sport model has a 1/4" square spar, and the giant scale is double the wingspan, it e probably doesn't have a 1/2" spar. Sheeting will usually not double, but will increase by 1.5. Take a look at the plans for similar-sized planes and use them as a guideline.

Subsection: Fuselages


Question: Do I have to wait for hours for glue to harden?

Answer by Cain Fly
Apply your "yellow" resin glue, but leave the corners and some inside spot/s bare, and for big doublers a few spots along the edges. Join the parts and rub them together. Pull apart and on the spots still left bare, apply a drop of thick CA. Rejoin and QUICKLY align, then press for a few seconds. You now have a joined unit that allows you to continue without clamps/pins, etc. and the "laminated" unit strongly resists any warping that the water based glue might induce.

Question: How do I make fiberglass molds?

Answer by Roger Neal
Here's a link on fiberglass mold making.

Subsection: Foam wings


Question: How to repair large holes in a foam wing?

Answer by Craig Greening
If you have any spare foam you could enlarge the hole to a uniform shape and insert a new piece then resinstall the dowels, failing that you could try some expanding foam and carve/sand it to shape after it sets. Check the compatibility of the expanding foam with your wing before using.

Answer by J.D.
and bear in mind that most, if not all, expanding foams are a one-time use. At least the ones I've come across were.

Question: Where can I find `thin' epoxy for glueing balsa sheeting?

Answer by Dave Mosley
most epoxies can be 'thinned' by heating - mix in paper/wax dixie cup and place on a "coffee cup warmer" or similar insulated heating device. longer cure time epoxies allow time for heating.
I use 1 hour epoxy, heat it up to about 150 degrees F. this tends to reduce the viscosity by about 50%, and makes spreading a thin layer possible.

Question: I'm looking for glue that doesn't dissolve the foam. Suggestions?

Answer by Icrashrc
Polyurathane glue is the best i've found for foam. It expands as it cures and make the whole area around the joint stronger. As an example I just recently glued a 1/4" hardwood dowel thru a piece of 1" white foam. I didnt realize how crooked I had drilled the hole until after the glue was set and I went to assemble the parts. I actually broke off the dowel by hand without hurting the foam it was glued into. Look in a good hardware store or somewhere like home depo or lowes for it.

Subsection: tools


Question: I want to build a foam cutter, any ideas?

Answer by Gerrit Hiddink
You can download plans for building your own foam cutter here:

Subsection: Covering


Question: What kind of iron do I need to apply the covering, can I use a heatgun? How does covering work?

Answer by Jim McIntyre
You need a proper iron, a clothes iron is too heavy, bulky and hard to control heat correctly. You can use a heatgun especially around compound curves like wingtips etc. It's not absolutely necessary though. You would also need sharp razor blades or a trim cutter. A sheet of glass is also handy for cutting pieces to fit or tacking colors together. The process of covering works as follows: Prepare the surface (sand, sand & more sanding). Clean with tack cloth.Prepare a clean area to work.plan your covering order, paying special attention to material overlap. cut pieces oversize Remove backing!check iron for correct heat (process explained on film instructions) tack around perimiter then seal around perimeter (never tack to inner surface or it will wrinkle when you shrink) Cover all surfaces b4 shrinking. Shrink opposing sides evenly, periodically checking for warps and heating opposite side to remove. Above all, keep everything clean. Use a sock for the iron and change it often.

Answer by Andrew E. Mileski
Check the Topflite (Monokote)/Coverite (Micafilm)/Carl Goldberg (Ultra Cote) web sites. At least one of them has step-by-step instructions and pictures for covering a wing. You might also consider buying the book "There Are No Secrets" by Higley.
Don't try to cover using a single piece. Wings: bottom, top. Fuselage: left, right, top, bottom.
It doesn't hurt to leave a small 1 inch gap near a center edge, so that air can escape while shrinking the rest. Seal this area last.
Use a soft 100% cotton cloth to gently press the heated film onto the structure.
With a bit of heat, and some effort, you can always remove the film and start over. Though I recommend trying to get it right on the first attempt!

Question: What is the lightest type of covering?

Answer by John Hawkins
If you want to save the weight of all the adhesive on a film that is not used to actually stick it down, try Litespan or Micafilm. You apply the heat activated adhesive only where you want it and I think it too is lighter than what is used with the self-adhesive films. Balsarite and Balsaloc are two adhesives. Litespan is by Solarfilm and Micafilm I think comes from The Great Planes group of companies. Balsarite is readily available. I believe Balsaloc comes from Solarfilm. It's a water based product while Balsarite is solvent based.

Answer by Fritz Bien
covering color weight [g/ft^2] comments
Monokote red 5.8
"" red 7.1 '71
"" white 7.3 '90
"" black 6.0 '85
"" yellow 7.5
"" platinum metallic 6.0
"" red transp. 5.5 '88
"" orange flour. 9.4
Ultracote dark red 8.5
Micafilm yellow 4.0 needs balsarite
"" red 4.0 ""
"" red 3.4 '81,""
"" pre primed 3.9 ""
"" white transp. 2.2 may(?) block radio signals (careful w/that antenna)
Sig Koverall white 4.3 nd dope/paint
Sig Supercote silver 4.8
Esaki Lgt Silk clear .97 nds care
5/8 glass/superpoxy clear 3.9 nds filler,color
jap tissue yellow .65 pre-colored
Spraylat paint 4.5 water-based epoxy, 1 ml thickness
clear nitrate dope 1.0 2 coats thinned 50-50
dope, gloss finish 7.0 8 clr, 4 color, 1 clr
dope, grain showing 2.0 over silk
Ultracote Plus Pearl Yellow 8.2 .0022 thick, self stick
Ultracote Cub Yellow 6.6 .002 thick
Transp. Ultracote Yellow 5.0 .0015 thick
Transp. U'cote Lite Red 3.4 .001 thick
Polyester Dress Any color 4.2 req's Balsarite & Lining "Polypuff" 2+ coats of dope
Coverite Space Age White 10.4 Pre-painted w/heat act. adhesive
Litespan White 2.6 needs balsaloc/balsarite Model Masters (Testors) flat enamel over polyester fabric and 2 coats 50-50 dope:
Polyester Fabric 4.4 g/ft2
Sig Nitrate Dope, 2 coats, 50-50 1.0 g/ft2
Enamel, 1 coat, Olive Drab 3.5 g/ft2
Enamel, 2 coats, Light Sand 4.2 g/ft2 (very light secondcoat)

Answer by Brian Felice
Might be laminating film. This stuff is nearly the same thing as the hobby coatings; polyester film with an adhesive on the back. It comes as thin as 1.5 mils (0.0015 inches) and heat shrinks just like the real stuff. Available at most large office supply houses or by mail order. Cheap too, about $.10 / foot for a 25 inch wide roll.

Question: Can I use silk for covering?

Answer by Pé Reivers
Silk was, and still is an unsurpassed covering material. What you need, is a silk with an open structure, not the tight-woven stuff. Model shops still sell Japanese silk, especially for models, but you can use any silk you can find that fits weight and structure requirements. The open weave is required for the shrink dope to do it's job properly. First dope all contact surfaces and sand smooth with fine emery, dope again, and run your fingers over it. There should be no fibres sticking out anywhere. They will snatch the silk and spoil your job. Non-shrinking dope may be used for that. You may want to mix in some talcum powder to fill small indentations, like wood grain etc. Cut and Lay out the patches of silk that you need, wet them one by one as you work. Dry out excess water between towels. Apply the patch to the structure. It will stick because it is moist. Smooth it and apply dope to all parts that have structure underneath. The dope will turn white, but not to worry, that will go away in subsequent coats. As the silk dries, it will tighten. After all patches have been applied, let dry. Then apply thin coats of shrinking dope; do not rush. Each subsequent coat will fill the weave more, and tighten the silk like a drum-skin. Coats will be dry before you reach the end of one job, be it wing or fuselage, so there is no need to stop working. If you do stop, your brush may harden between jobs, just leave them a while in the dope and it will be soft again. I use a flat 1.5" very soft brush. Nice thing about it is, that you can dope on patches for repairs, tear off parts of the silk and dope on new covering at wish. Normal enamels do not adhere well to dope, unless you prime coat with an automotive wash primer. Spar grade (cellulose based) paint (the ones that can be rubbed to a gloss) works great. You will find that it is easy to do, looks good, is easy to repair and lasts very well.

Answer by David Larkin
One problem when using silk is that the dope may run through and collect in unsightly lumps on the underside. To avoid this, many British 'vintage' flyers use the 'meniscus' method. They don't brush directly on the silk but on to a piece of silkspan tissue which they draw across the surface as they proceed.

Question: Where can I find more tips on monokote covering?

Answer by Joe L.
Look here:

Answer by Dr.1 Driver
Get Higley's book, "There Are No Secrets". It's a good book on covering.

Question: How to remove loose balsa fibres before covering?

Answer by sport_pilot
Assuming you are covering with a plastic film. Any good primer or sanding sealer would work. Or dope with talc powder added. Or go to the hardware store and buy a can of Parks sanding sealer. It is the same thing as nitrate dope with fillers added. If you are painting then you need a primer or sanding sealer compatable with the paint you will use.

Answer by Dno1939
Try dampening the wood with a wet paper towel or rag to raise the grain, then cut it off with steel wool.

Answer by Dennis Adamisin
If its just the "normal surface fuzz that balsa has, rub it with a piece of foam rubber, like you were sanding it. I read that in a magazine once and it works like crazy. It definitely improves the bond of the covering too.

Subsection: Construction techniques


Question: How can I reinforce the nose of my (foam) airplane with fiberglass?

Answer by Brett Jaffee
Fiberglassing over monokote would most likely not work well at all. For that matter, fiberglassing an EPP plane for this reason doesn't make a lot of sense. EPP is so great because it can absorb punishment by flexing or crushing, then bouncing back. The intent of fiberglassing is usually to add a hard, protective shell, which would defeat the purpose of the EPP (the glass would probably crack on the first impact anyway, since its on top of a flexible surface).
You would be much better just adding some clear packing tape to protect the bottom.

Answer by Edwin Smith
Do the epoxy glass method and you wont have any problems. I've done a fair amount of epoxy glassing to make cowls. Its really pretty easy. Especially if your going to leave the foam inside and it sticks pretty good to kote type coverings.

Answer by MSu1049321
if you're going to glass foam, be sure it's epoxy fiberglass and not polyester resin... that's the stinky kind that tends to eat foam.

SECTION 3:Flying airplanes

Subsection: Basics


Question: Do I really need ailerons to fly an airplane?

Answer by Ton Jaspers
Rudder only control works well with a di or poly hydral wing. Turning a straight wing design is hard to do with rudder only. A straight wing is less stable, it does not automatically level like a poly. On the other hand a straight wing gives much better performance. So, a high performance design will have straight wings and need ailerons.

Answer by Doug Hoffman
I agree that in many conditions a non-aileron glider can perform thermal turns well. In other conditions, such as gusty winds or "violent" thermals that can kick your glider around, ailerons provide superior roll control. Decouple the rudder and ailerons and, with practice, your control over the ship in turns is much better. Very flat,slow turns or extremely banked tight turns. But if you aren't trying to optimise and are just wanting to fly around, then if you prefer no ailerons by all means don't use them...
A flat winged glider will also land better, especially in a crosswind. The poly ship gets tossed around more with its "ears" sticking up.

Question: What battery voltage is considered safe for flying?

Answer by Alton
Most people quit flying at the rated voltage (4.8 and 9.6). What really helps is to discharge the batteries at a constant rate and note the batteries performance. Nicad voltage will drop rapidly when the cells are exhausted without warning. This is the reason for stopping at the rated voltage. It is still helpful to know the characteristics of YOUR batteries. As batteries begin to need replacing, the voltage at which beyond that the battery will be exhausted begins to increase.

Question: The antenna of my receiver is too long, can I cut it?

Answer by Gerrit Hiddink
No you can't! If you cut off, say, 10%, then the reception will be a lot worse than 10% decrease. The length of the antenna is tuned to the frequency of your set, so if you modify the length, it won't fit the frequency anymore. The best layout of the antenna is a straight line, even if this means a dangling wire at the tail of your plane...

Question: I want to go flying in the mountains. What is the effect of the higher altitude on my engine?

Answer by Plane Guy
1. Air pressure falls with altitude, so the air entering your carburetor is less dense at altitude, therefore you'll need a slightly leaner mixture (i.e., less fuel to mix with the reduced air in order to achieve the proper mixture ratio). 6K-7K altitude is right up there - I'm sure you'll have to go slightly leaner.
2. Your airplane will have to achieve a higher groundspeed to get the reduced amount of air at that altitude to flow over your wing and produce enough lift. Expect longer time to get on the step, and a longer takeoff run and shallower climbout angle. Please see the Koch chart at this URL:
Please also note that your airplane will appear to stall at a higher speed at that altitude. Its stall speed isn't really higher - it's just that the air is thinner and you need to move through space faster to get enough reduced-density air over your wings to sustain flight.
3. A lower-pitch prop will improve thrust at the lower airspeeds associated with takeoff and landing, but expect a slightly lower cruise speed. It should also improve climb angle. Not sure about the effects of nitro (seems like if your engine is happy with 5%, I'd stay with 5%, but that's just a gut feel and not true knowledge)

Subsection: Hi-start (bunchee) launching


Question: What should a towhook look like?

Answer by Joel
It should look like an L. From the bottom, it should be about a 1/4" inch, and the length should be about an inch. This sould work good. The material should be music wire. I would use 1/16" (1.5 mm, GH), that should probably work. If you could bend something a little thicker, then go ahead. Make sure it is securely mounted to your plane. There is about 10+ lbs. of pull on the histart, so maybe put a plywood base and epoxy the hook to that and secure to your plane since it's a foam plane. I would put part of the wire going into the foam and use a lot of duct tape to hold it. It may look crude, but hey! It works!

Question: Where should the towhook be located?

Answer by Howard Lute
The towhook should be located at the Centre of Gravity, or slightly (1/4 - 1/2") forward of the CG.

Question: When using the hi-start, the hook pops off. Why?

Answer by Jeff Reid
Your models CG may be a bit too far forwards which requires more up trim. This makes the model "speed" sensitive. At higher speeds, like during a launch, the model will want to pitch upwards (nose up). You can leave the trim as is and feed in some down elevator to compensate for this effect. During the up-start swing, tension in tubing will decrease along with speed, and you can reduce the amount of down elevator, usually when the tow line passes 45 degrees or so.
The other fix is to trim you plane to be more neutral (CG further back, less up elevator trim). This will make it less speed sensitive, but you may still need to feed in some down elevator during launches. It's a compromise between how it glides and how it launches.
Another option if you have a computer radio would be to program a "launch" switch to feed in some down elevator during up-starts.
One other option is to move the towhook even more forwards to compensate for the pitching up at speed.

Question: What are proper dimensions for a hi-start?

Answer by Jeff Reid
My preference for line to tubing length ratio is 3.5 to 1. For example, with 25 feet of tubing, I would use 87.5 feet of line. I pull back 300% to 350% depending on conditions and weight of glider. In this example case, (25 feet tubing), I'd pull back 75 to 87.5 feet.
With 50 feet of tubing, I'd use 175 feet of line (40 pound test monofilament fishing line). I pull back 150 feet (300% strain), to 175 feet (350% strain) depending on the conditions. This setup would require 375 to 400 feet of space for a full launch.

Subsection: Winch launching


Question: What motor to use in a home-made winch?

Answer by Tom Rent
You have to go to a Starter Rebuilder shop in most areas, not a parts store. I have found them at parts stores but they charge too much in my opinion. Starter rebuild shops know what they are doing and can make up what you need. The first time I went to a starter shop to ask on these they knew exactly what these were and had several on the shelf to sell to me. The most common is the #3136 as described below. It is used on some front-end plow systems to lift the blade so they need to keep some in stock. I opted to have one made up with four 6 volt coils. See below:
RC Soaring Ford Long Shaft Motor types
SPORT: 12 Volt, 2 Windings: Rebuild #3115 or #3117. Original #'s were SA 519 and SA 622. [Application: Average user]
BIG SHIP: 6 Volt, 2 or 4 Windings (run on 12V): Rebuilt #3109, #3110, or #3112. The Coils are Heavy Duty and when run at the higher voltage it does induce more stress so rebuilding every few years might be necessary.[Application: Contest winch ....get's hot so you need to cool it. Consider buying ball bearing end plates] These one also eats batteries.
BEST BUY: 12 Volt, 4 Windings : Rebuild #3136 (Original # C 3 NF 11001C or C 3 NF 11002C.
Make sure you have one with a 5.75" shaft as this fits most drums that are available. There are 5.25" shafts around. Make sure the shaft is straight too.
As for what vehicles used these originally, I am not 100% sure but I did hear at one time they were used in 1963 Ford trucks, but don't quote me on that.
Most Starter shops can make up what ever you want as the coils and cores can be mixed and matched. I've been able to get these for between $40 and $70 depending on what work they need to do to get the one I want put together.
For the recreational flyer, the BEST BUY is a solid care-free configuration. I fly the BIG SHIP configuration and do have some heat problems on hot days with heavy ships and heavy usage ..... even had one cease up due to heat.

Question: And what diameter winch drum should I use? Do you have more building tips?

Answer by Ingo Donasch
Use 40-50mm diameter and choose a drum as long as possible to avoid excessive buildup of diameter at the top of the lauch. (our winch has 50mm and it seems almost too much). f3B winches have 40mm.
Don't forget the brake, it's very important. The pictures give in the urls below should give an impression how to attach the brake. duplicate the brake lever as close as possible to these pictures. if the angle and length is not right (+- 0.5in!) the brake does not work properly. I needed an additional 1oz weight on my brake because I didn't copy that winch excactly.

the pulley weel for the brake is from ace hardware. the line is braided nylon 170lbs (or better should be, the line you see on the picture is way too heavy) and 125lbs line snaps to often.
Mount the turnaround on a pole that it is 2-3ft above the ground. this reduces drag and the line lives longer. if you can also mount the winch 1-2ft above the ground that would even be better.
No problem towing a 120" f3j ship with this winch. For the battery: it must be a deep cycle type. get one that as a good warranty on it, you'll need that! Keep the receipt. do not use the flimsy marine type connectors, I burned one through the battery because the connector was a little bit corroded and heated up. (200A is nothing to fool around with!). Use the thickest cables you can get and make them as short as possible.

Subsection: Electric flight


Question: What type of batteries can I best use? Is NiMH a good choice?

Answer by Paul
Depends on the application... In general, with NiMH, you can expect about 50% more duration over high capacity NiCD or 100% over "standard" NiCD. Higher internal resistance than NiCD. Beware high current apps unless you are using high capacity NiMH, with penlight sizes (<1500ma) as current load increases over 8-10a, capacity decreases sharply. Can be recharged fewer times than NiCD. They do not like to be fast charged.
1) NiMH works well for receivers, transmitters and other low current draw (5-10 amp) applications.
2) Penlight-type (<1500ma) NiMH works well for eFlight in low current draw (5-10 amps) Speed 400 type appliations, but only if your interested in low-throttle long duration flights. They work well in slow flyers like the Wingo.
3) High capacity NiCD (i.e. AE type cells) also works well for lower power Speed 400 stuff, offering more power than NiMH over a reduced burn time... and more duration than fast chrge NiCD. They can take some fast charging, but it isn't recommended.
4) Larger capacity NiMH (>1500ma has made great strides in delivering more power, but are still best suited for duration flights on larger ePlanes. Can be recharged fewer times than NiCD.
5) Fast charge NiCD (i.e. AR type cells) offer more power output (lowest internal resistance) than any of the other cell types. Widely used for high performance applications, pylon racing, F5B, aerobatics and sport flying. Heaviest batteries of the bunch, but they can put out 20-30+ amps and are very rugged. Designed to be fast charged, so turn-around time is shorter.

Question: After some minutes, the motor cuts out momentarily. Why?

Answer by Brian Findlay
I noticed that this phenomenon always happens at the same relative spot (ie geometry), so I am positive that it is the orientation of the reciever antenna. Since the antenna is completely buried in the wing, it forms a 'plane'. When the plane is edge on to the dipole of the transmitter antenna, it sometimes blips. I suspect that if the reciever wire was trailing, this wouldnt' be a problem. (course, tangling with the prop WOULD be a problem!).

Subsection: Soaring


Question: What is a thermal?

Answer by Gerrit Hiddink
A thermal is a bubble of rising air. Thermals are created by earth surfaces (parking lots, roads, forests) that are warmer than surrounding surfaces, for example because they're heated by the sun. These bubbles (or columns if they're continuously fed) of warmer air rise upwards, just like a balloon does. If your plane happens to be inside that bubble, then it will also rise, or descend less rapidly.

Question: How does one fly thermals?

Answer by Dan
Inside a thermal, you fly circles or figure 8's. It depends on the size of the thermal which is basicly a column of rising warm air.

Question: How do you find a thermal, how to know the plane is climbing?

Answer by Dan
I cross back and forth over the field to find a thermal, looking for that warm spot. A good thermal can make the plane seem like its riding up in an elevator sometimes. Lift and altitude climb can be VERY noticable! There are a lot of tricks (most of which I dont know) but mostly I just fly back and forth in straight lines till I notice the plane seems to be pushed aside or deflected. Thats a thermal. I then turn the plane back towards that deflection. Usually, you can see the plane climb once you are in the thermal, sometimes quite a lot! Then its just a matter of sticking around that spot of sky feeling your way around to gauge the size of the thermal.Lazy circles or figure 8's.

Question: Can I gain altitude by flying into the wind like a kite?

Answer by Jeff Reid
No you cannot, a glider or planes only reaction to a steady wind, is that it's ground speed will vary while it's air speed remains basically constant (if the plane/glider is flying level...), depending on the direction of the glider.
This may be an optical illusion, any time you fly an RC-model away from you, it can appear to be losing altitude, and when it's flying towards you, it can appear to be gaining altitude, due to the visual angle above the horizon that you're viewing the model with.
With an eletric glider, when viewed from the ground, a climb will appear to be steeper when it's flying into a headwind as opposed to a tail wind. Relative to it's airspeed, the climb is the same.

Question: What about so-called `dynamic soaring' ?

Answer by Joe Wurts
The energy increase in dynamic soaring is due to flying into a airmass that gives you a change in airspeed "free" of charge. One of the slopes that I have been flying at has a very pronounced "razor back" to it (Parker Mountain near Acton CA). What is really neat about it is that the air behind the hill is completely separated. That is, it can be blowing 25 mph on the face, and behind the hill, it is almost calm and sometimes even blowing softly in the opposite direction. It turns out that this is an absolutely perfect set-up for dynamic soaring. All you have to do is fly straight down-wind over the hill into the calm air and turn around. If you want, when you come back over the upwind face, turn around and repeat. With each turn, you get an amazing boost in the energy of the glider. The first time I really played with this was with my Floyd, and on the second go-around I fluttered the wings. The plane will take an extended vertical dive without any possibility of flutter, so I was able to get it to above the terminal velocity of the glider in horizontal flight!!!
One thing that is especially wild is when the wind dies down a bit, and you can just stay up in the normal lift in minimum sink mode. Start doing the orbiting for the dynamic soaring and you can get up to about three times the speed that you can when you just fly in the normal slope lift. Wild stuff.
If your slope has separated air behind the hill, and you do not mind occasionally crashing while you learn a new trick, give this a try. Caution, I'd recommend trying this maneuver out sometime when you have the hill to yourself. It takes a little getting used to... And a hint, the lower you go on the downwind side, the better off you are (more delta-vee typically).
Lets go through an example here. Lets assume a 25 mph wind on a slope, with the backside completely calm (I've flown at slopes where the wind on the backside is blowing towards the top at 1/2-2/3 of windspeed, but we will use the worse case above). I turn downwind with 25mph airspeed, and with the windspeed, I get a 50 mph groundspeed. I then enter the calm air, and with the 50 mph gorundspeed, I now have a 50 mph airspeed as well. I turn around, and fly into the active wind on top/in front of the hill with this 50 mph groundspeed and the 25 mph wind speed I now have 75 mph airspeed. Without drag/turning losses, each turn adds 25 mph to the airspeed! You may also want to look here:

Subsection: Airobatics


Question: What is 3D flight?

Answer by Pé Reivers
3D flight is what it says, three-dimensional. Of course all rc flight is three-dimensional, but 3D is extreme, like the cobra that Russian jet fighters exhibit. It is even more extreme than fun flight, because very large control inputs makes the plane go far beyond the flight envelope. That creates totally new flight figures: 3D

Subsection: Night flying


Question: How can I light my airplane so I can see it?

Answer by Howard Lute
I use the Ultra Bright LEDs avail from Radio Shack...they are VERY bright and are easily aimed across the wing under side which makes it very easy to spot and fly the plane in pitch black nite.

Question: Where can I find more information on lighting systems?

Answer by Alan T.
Check this URL:

Answer by Craig
Here's another lighting system that is much cheaper and works just as good as the night-ops:

Subsection: Charging batteries


Question: With what rate do I have to charge my battery with capacity C?

Answer by Red S.
Minimum charge rate recommended for fully charging a pack is C/20, but this would take 32 hours or so.
Have a look at Red's R/C Battery Clinic at

Question: I have many more questions about batteries! Where can I find answers?

Answer by Gerrit Hiddink
You can find a Battery FAQ at or at

Subsection: Engine


Question: How do I supply power to a glow plug? How much does it need?

Answer by CDance7412
Glow plugs usually require 1.2 to 1.5 Volts of DC power. Your local hobby shop or Tower Hobbies can provide you with a lock-on adapter that has a built in battery or, If you have one, plugs into pour power panel.

Answer by Mike
D size alkaline 'batteries' have really improved over the last 10 years. I usually have a 4000mah NiCd D cell for a glow battery but forgot to charge it for my first flight last Spring so I grabbed a Duracell D cell from a flashlight. I used it all summer, (not a lot really in my case, only maybe 30 to 40 engine starts).
It's long way from the days of the Union Carbide 1.5 tennis ball can size zinc-carbon cells with the screw terminals on top.

Question: What fuel do I have to feed to my engine?

Answer by J.D.
For Cox engines, I always used to use Cox Glo Fuel. From what I understand, these small engines up thru the .15 like high nitro, at least 15%, preferably 20%.

Answer by Patricio W. Concha Erilkin
Here, due to the expensive of the the fuel, most guys with .049's and .061's use just 5% nitro fuel (mostly powermaster) ... and no problems at all !

Question: Do I really need fuel with nitro? Can't I run an engine without?

Answer by Pé Reivers
Supertigre, Webra, Moki, MVVS and many others advocate use of nitro. They also advocate to adjust compression ratios when large volumes of nitro are used.

Answer by Paul Mcintosh
I have been running all manner of engines for many (35+) years on all types of fuel. No-nitro fuel, while cheaper, does NOT run as well in the majority of engines made today. I usually run 5-10% nitro in all my 2-c engines and 20-50% in my 4-c engines. I keep hearing about Laser engines and how great they are on no nitro. I don't see anyone telling me what size props they turn at what RPM. And, they cost up to 3 times as much as other 4-c engines available here

Question: Is there an RC throttle for a Cox TeeDee .051?

Answer by Mike
I never saw the TeeDee throttle version but I have a Cox .049 with an exhaust throttle that worked fairly well. It is basicaly a ring around the lower part of the cylinder that is rotated to partially cover up the exhaust ports and limit the flow. It also had a muffler feature of sorts that really didn't do much. I think this method might work on a TeeDee too. It would be a simple thing to make and try.

Question: How do you start a Cox 0.49 engine?

Answer by
First attach the fuel line to the engine, shut the venturi with your finger and turn the prop a few times just until fuel fills the hose. Then, put 2-3 drops of fuel through the outlet holes in the cylinder, turn the prop twice, attach the glow plug and start the little one. Be patience, it may take a while till you get it...

Question: There's a lot of black stuff coming from the exhaust, and the engine is brand new!

Answer by Gerrit Hiddink
This seems to be normal for some engine types, such as the Zenoah G23 and G62. It seems to be a by-product of normal break-in, and is nothing to worry about. It should taper off after about 2 or 3 hours runtime.

Question: In the winter season, the oil thickens and the engine doesn't run nice.

Answer by Pé Reivers
Route the fuel line behind, and against the cylinder. This provides sufficient heat for stable cold weather operation. Your trick stops working, when the plane is fuelled up and has cooled down by propeller wash and flight wind, leaving you with not quite correct needle settings. Denser winter air containing next to zero water vapour means richer settings to provide the fuel to match the oxygen content and restore fuel to air ratio's.

Question: How can I modify my engines to get more power from them?

Answer by Ray S.
If you're interested in increasing power with a 2-stroke, there are several areas which pay off. First, increase the base compression (the compression ratio within the crankcase) as much as you can. Second, the exhaust port area does NOT need to be over 65% of the inlet port area, and make the inlet port area as much as possible. Third, our present design 2-strokes pass over 50% of the incoming fuel/air misture straight out the exhaust without burning it. A baffle needs to be added to the piston to prevent some of the inlet gas from going straight out the exhaust. Make sure you use "squish" area in the combustion chamber to retart detonation.
Yes, you can do it but it will take time. No easy task.

Question: When I inject fuel into the exhaust hole and turn the shaft, I can hear air escaping. Does this mean I'm losing compression?

Answer by Dr1Driver
A piston/cylinder fit is never perfect. You'll always have some escaping air/fuel, especially if the crank is turned slowly. You didn't say if the engine is ABC or ringed, but an ABC engine only fits well at operating temperature, and may actually be tight when cold. A ringed piston/cylinder will sometimes leak badly at room temperature, but will tighten up when hot. If it still runs well, don't worry about it.

Subsection: Slope soaring


Subsection: Flying with simulators


Question: I'm flying with RealFlight and my 5th channel doesn't work. How come?

Answer by Steve Lewin
The 5th channel never will work if you are using the joystick port. It's only got 4 analogue channels. If you are trying to use the printer port like the real interface does then you will need the software wich reads it. The basic program only reads the joystick port.

Question: I spent all my money on an airplane and can't afford a simulator...

Answer by Gerrit Hiddink
Download Ron's free simulator at

Subsection: Indoor flying


Question: Where can I learn more about indoor flying?

Answer by Pete Christensen

Subsection: Flying in Championships


Subsection: Paperwork


Question: I live in the U.S., and somebody told me I had to be a member of the AMA. Why, what is AMA?

Answer by Murray Lane
For U. S. residents, an organization well worth joining is the Academy of Model Aeronautics (AMA). They are the modelers' main voice where it matters---they liaison with the FCC, the FAA and Congress. It is an affiliate of the National Aeronautic Association (NAA) and is the US aeromodeling representative of the Federation Aeronautique Internationale (FAI). Membership in the AMA also gets you $1,000,000 of liability insurance, without which most fields will not allow you to fly. You also need to be an AMA member to participate in contests. Besides, you also get a magazine, `Model Aviation' which is rather good in itself, and it keeps you informed about the state of the hobby. Membership is $42 per year.

Question: What about other countries?

Answer by Gerrit Hiddink
In the Netherlands, there's the Koninklijke Vereniging voor the Luchtvaart (KNVvL). It works about the same as the AMA in the United States: you get a liability insurance, a magazine, and they represent the airplane modellers on a national level. Many clubs only allow you to fly at their airfield if you are a KNVvL member, afdeling Modelbouw.

Subsection: Safety


Question: What is the 'failsafe' mode of my transmitter?

Answer by British Model Flying Association
The term HOLD refers to a scenario whereby the servos HOLD the position they were in just before some kind of interference arrived. The term PRESET refers to the moving of the servos into pre-programmed positions which were defined by the operator before flying, and FAILSAFE is a generic term to cover both.
If you use a typical Computerised Transmitter, or have members in your club who do, you should be aware of the following basic findings.
Almost all sets give an automatic PRESET/HOLD feature within the program as soon as PCM is selected. This failsafe becomes operational if interference occurs at the receiver of the model or the transmitter signal is lost. Control returns to the pilot when the interference ceases. If interference does not cease, the pilot will not regain control.
The failsafe software cannot be totally inhibited. It will either hold all (HOLD) or go to positions pre-programmed by the pilot (PRESET). Some sets allow a combination of this feature. i.e. some channels will go to a PRESET position and some controls will HOLD at their last position.
The default setting if nothing is programmed is to HOLD at last input position, including throttle. This will become operational after a pre-determined interval set by the pilot (1.0 seconds, 0.5 seconds or 0.25 seconds) or after a default interval if nothing is programmed. The interval is the length of time it takes, starting the moment interference occurs, until the servos assume their pre-set positions. [...]
We recommend that particular care is taken by all individuals when operating on PCM or when swapping from PPM to PCM to ensure that the PRESET/HOLD feature is correctly programmed with throttle to tick-over (stopped in the case of electric power).

Question: I'd like to open a bay door in-flight and drop candy or something onto the croud.

Answer by Chollie
This sets off alarms. AMA (American Modeler's Association) rules do not allow over-flying people on purpose. (Check your local law for the situation in your country, GH) Dropping anything at all, however well intentioned or however benign, onto or among those people opens wide doors to potential liabilities and lawsuits.

Answer by James G. Branaum
I have seen it done with some care. Since there is a prohibition against overflying spectators, you will have to learn how to 'drop' the candy while in a moderate G loaded turn. That will 'throw' the candy. Your task, should you choose to accept the challenge, is to determine how to control where the load lands....

SECTION 4:Airplane maintenance and repair

Subsection: Radio and batteries


Question: How to replace a broken receiver antenna?

Answer by Gerrit Hiddink
You can replace the antenna by yourself, if you know how to use a soldering iron. If not, you may get used to it by practicing on an old piece of circuitboard.
If there's still a piece of wire sticking out of your receiver, then you don't need to replace this piece. It's better not to, because then you don't have to solder your receiver circuitboard. There might be a risk of overheating if you're unexperienced.
Replace the wire with something flexible, with enough strands in it. But whatever you do, make sure the length is the same as the original! The length varies with the base frequency of your transmitter. Always do a range check after repairing!

Subsection: Surface cleaning


Question: How do I remove oil and grease?

Answer by Bob Peck
I use a homemade brew that works very well, and is inexpensive. It removes grease and cleans up without streaks.

1 cup Rubbing Alcohol
3 teaspoons amonia
3 teaspoons liquid dish soap
1/2 gallon water

Subsection: Balsa wood care


Question: How does one go about getting oil out of the balsa? I heard it can be done with 'K2R', where to find it?

Answer by James G. Branaum
Look for 'K2R' in the household cleaners isle of your local Albertsons.

Answer by Paul J. Burke
K2R is a very good oil-soaker; used after a fuel tank incident in fuselages, it does a good job. However, California has just -expanded- the list of illegal chemicals to keep us safe from ourselves.. I haven't seen any at Albertson's for close to a year.

Answer by Dr1Driver
K2R can be found in Wal-Mart. Glue will not stick to oily wood, and the wood will remain weak unless the oil is removed and the wood soaked with thin CA.

Answer by B C
We had a Lazy Bee that got oil soaked and from advice we used Corn Starch after using K2R with no results. Applying corn starch to the area and heating with covering iron the oil was gone!

Answer by Grain
If you can't find K2R then try mixing alcohol and corn starch together. Heavy on the alcohol, but not to the point of dripping. This will work, but it will take several applications if it is really bad.

Answer by ratman
I soak the affected area with rubbing alchohol then cover with a paper towel. then iron the paper towel till dry. repeat till the paper towel comes clean. will at least get it clean enough for the covering to stick.

Answer by Al Eastman
Get a bag of plain old kitty litter and bury the fuse for several days. Oil all gone!

Subsection: Engines (gas and electric)


Question: How to break-in an engine, especially a Webra?

Answer by Dr1Driver
Run standard synthetic/castor if it's ABC, or total synthetic if it's ringed. Webras take a little longer to completely break in than some others. If it's ABC, break it in only slightly rich, if ringed, richen it more and take a little longer.

Question: How to break in an electro-motor?

Answer by Gerrit Hiddink
You should break in an electromotor for about 30 (!) hours on about a quarter of its voltage, or half an hour on full power under water. You have to do it under water to make sure it doesn't overheat and to prevent sparking (else your collector will burn). Some sources suggest to use destilled water instead of tap water; destilled water is a worse conductor than tap water so you will get less unwanted chemical reactions due to the presence of electrical current.

Question: How do I clean my engine after the flying season is over?

Answer by John Equi
I've been using a 5% mix of ammonia in paint remover (clear jelly) for years, works good if the stuff is at room temp or slightly warm. The steel parts can be cleaned in spray oven cleaner, and the piston tops sanded on a flat with 600 and oil. All other parts can be cleaned with 5x steel wool. I ultrasonically clean everything 2 or 3 times before reassembly in lacquer thinner.

Question: How can I thoroughly clean my engine?

Answer by Vance Howard
go to a truck stop. there should be a product made by Eagle One for cleaning oxidization off of aluminum, forgot the specific name (it's called "Mother", GH), it comes in a spray bottle, spray it on, let it sit 10-15 minutes and rinse off with water. pretty nasty stuff, do it outside and wear rubber gloves. works great on truckers big aluminum wheels, should work on the engine. remove any plastic parts and gaskets first though.

Answer by Miles
Go and get an old crock pot and fill it with antifreeze. Cook the engine, dissembled, for about 24-48 hours. It should come clean with no problems. (Do ventilate the area. You can reuse the fluid for future cleaning activities, but do not use the pot for food purposes afterwards ;) , GH)

Answer by sport_pilot
You can just let it soak in denatured alchol for a day or so too.

Answer by John Laird
In UK , some of us clean engines with paint and varnish stripper - as used to take paint off wood etc in home.
Active ingredients are methylene dichloride and methanol - stuff is hick - paint on and leave for 20/30 mins then clean off with water and tooth brush.
Not used yet for 4 strokes but suggest ok if kept away from rubber(?) seals for push rods/carb etc and off course - block the carb / exhaust .

Subsection: Covering


Question: How do I reglue pieces of covering that have let loose?

Answer by misc
If the cover-glue has vanished due to dirt, fuel or cleaners, you can clean the attachment surfaces with Windex. Apply an adhesive like Covergrip, Stix-it, q Balsarite (from Coverite) or Balsaloc, allow to dry and seal by heating with an iron.
Balsarite is a paint-on, heat activated glue. It was/is used for attaching Coverite fabric covering to model surfaces. Pull up your monocoat pieces a little, and jam some BalsaRite under them using a small brush. It dries in about 15 minutes, and then take your heating iron and reseal the monocoat down. Clean up an excess BalsaRite that you've smeared on the plane with some acetone, and you're all set! Make sure you clean your brush with acetone, or dope thinner, 'cause BalsaRite will gum it up real good.