Aero Mail
Antitorque Update
Frank Tiano (via e-mail)
I read with amusement, and a bit of shock, the article featured in Model Aviation about adding "weight" to the right wing of a model aircraft to counteract torque and prevent swinging to the left on takeoff.
I am amazed that a magazine that caters to modelers would print something so erroneous! So with an extra pound in the right wingtip, how safe and how stable is that model at slow speeds, like, say, when it's time to land?
Quite a strange antidote for yaw.
Frank Tiano via e-mail
Michael Ramsey, MA Editor
Your reaction isn't surprising; it was mine as well, until I talked about the idea at length with the author. However, we're pleased at this point to see how many readers with the same problems cited in the article are expressing the success they are now having, thanks to Mr. Hunton's idea.
The method is probably best considered a fix suited for RC pilots with less experience, but it can help ensure that new models get into the air more safely. When those pilots gain more experience, they can explore other trimming methods. But in the meantime, they don't hate aeromodeling because they can't get their models off the ground.
The antitorque device can help some RC pilots, which makes the article worthwhile, don't you think?
Michael Ramsey MA Editor
John Hunton ([email protected])
I am deeply honored that you would take time to comment on the antitorque article. I am also pleased to read Michael Ramsey's reply, with which I agree fully. I have received a few other comments from highly experienced pilots like yourself that are in favor of people learning to correct for torque, P-factor, etc., at takeoff by proper utilization of the controls.
For the RC pilot that intends to excel at flying, the tip weight system is not for them. But for the average Sunday flyer who just wants to see their creation in the air, the tip weight system will work well and, as Michael Ramsey suggests, they can learn the proper controlling methods after being able to take off and fly successfully. Thanks for your comments.
John Hunton
Jeff Edstrom (via e-mail)
I read John Hunton's story "The Antitorque Device" and said to myself, "That's crazy!" You build a plane to balance nose to tail and tip to tip. Then you say I have to add weight to the right wing? Madness. That will add drag on takeoff to the right ... hey ... wait a minute ... hmmmm.
All joking aside, that's an interesting challenge to the lateral balance paradigm. And of course, as the article states, this is just if you need it. But if you knew that an aircraft (like my Yellow Aircraft P-40) pulled to the left and needed right rudder on takeoff every time, a person might build a spot into the wing during construction that could hold the needed antitorque device and still allow for changes as needed. Thanks, John!
Jeff Edstrom via e-mail
Marcus Vann (via e-mail)
I read your article in Model Aviation and I will try your weight idea. I am new to RC and having problems with left torque.
When taking off I have crashed the plane twice on takeoff and repaired it. The plane is a Great Planes Extra 300, with a 62-inch wingspan and Magnum .65 engine. It looks like 1.25–1.30 oz on the right wing would help.
I also have a 54-inch Ultimate biplane with 1.20 two-stroke. What would be the correct weight and which wing, upper or lower, should I install the weight on?
Marcus Vann via e-mail
John Hunton (reply to Marcus Vann)
Your experience is exactly the situation that this antitorque device is designed to cure. Please try it with the weights that you suggest and let me know how it goes. Be advised, however, that for any model that flies inverted, the weight, while helping on takeoff, will have an opposite effect during inverted flight.
On the biplane, I suggest that you place the weight on the lower wing, because it will have a very small tendency to help keep the nose down on takeoff. As to the amount of weight, just try something small, say an ounce, and add or subtract until your takeoffs are completely torque-free.
John Hunton
Aero Mail
Continued from page 7
Chet Ferrel (via e-mail)
I read your interesting article in the October issue of Model Aviation. Good info. However, I have one question. The weight on the right wing: how will that affect the plane if you are landing with reduced power and/or dead stick? It appears that the plane would be rolling right because of being out of balance.
I'm flying a scratch-built Starduster Too: 82-inch wingspan biplane, G-62 for power swinging a 22-10 propeller and weighing 32 pounds.
I just finished a scratch-built P-51, 102-inch wingspan, 3W 75i for power swinging a 26-10 propeller and weighing 31 pounds. I would appreciate any input you can provide.
Chet Ferrel via e-mail
John Hunton (reply to Chet Ferrel)
There are three aspects to the landing scenario; perhaps the overriding one is:
- If the landing approach goes awry and you have to suddenly apply power to go around, then this system works just like takeoff and prevents the adverse effects of torque. Many models without the weight are lost in this scenario.
- If we look at normal trimmed cruise flight without the weight, the controls are set to counteract the torque produced at cruise. If power is increased the model will turn left and climb; if the power is reduced the model will lose altitude and turn right. With the weight, when power is increased the model is less apt to turn left and the opposite for a decrease in power. So the weight helps in accelerating flight and in decelerating flight such as when approaching for landing.
- The area of stall is of question. If the model stalls, of course the weight (although small because of the long moment arm of the wing) would tend to make the right wing drop first. But if you look at the dynamics of a stall, the model must decelerate to get to the point of stall and the weight will help counteract the trim that was put in at cruise.
For your particular models I would certainly add the tip weight conservatively and examine the reactions of the model in all phases of flight.
John Hunton
Lee Gann (via e-mail)
I came to the same conclusion many years ago when taking my early flight instruction. The given information (still today) for P-factor is, of course, right rudder as power is applied. This is said to counter a spiraling prop wash hitting the left side of the vertical fin. The reason given is: the most powerful control at zero airspeed is, of course, rudder.
Your theory is correct, and I hold the reason the plane will swing left is simple torque—putting more mass or pressure on the left wheel. I have tested this with ribbons held in the prop wash—full scale and models—and saw no spiral. To the new aviator, though, rudder is what you have to work with! I enjoyed your words.
Lee Gann via e-mail
Glenn LeCartz (via e-mail)
Your article described to a tee what happened last week when I was flying my E-flite Texan. On takeoff it began to roll left and although I applied right aileron it continued to turn left. I'm not sure how but I managed to save the plane.
The Texan has a 54-inch wingspan and uses a Power 25 motor. I'm thinking using your formula—0.5 ounces of weight would be about right. Also the plane has right thrust built into the motor mount. Would this possibly have an adverse effect using your device?
Thanks for the great article and any advice you can give me about my plane. Another takeoff like the first one may result in a heart attack.
Glenn LeCartz via e-mail
John Hunton (reply to Glenn LeCartz)
I am very glad that you were able to save your Texan. This design is noted in model and in full-scale sizes for having bad tip-stall characteristics.
The built-in right thrust should not have much effect on the theory, although you may not need quite as much weight. For the Texan I would start with the full amount (possibly with stick-on weights) and reduce it if necessary. Good luck!
John Hunton
Glenn LeCartz (follow-up)
Thanks for getting back to me so promptly. I tried a half ounce on Sunday with noticeable, positive results. Now all I have to deal with is the rest of the quirks of flying a Texan. Thanks again!
—MA Glenn LeCartz
Transcribed from original scans by AI. Minor OCR errors may remain.
