Twister with a 40?

How far back, if any, should an OS 40 be moved on a Twister? I plan to build it stock, and it is definately a stunt trainer for me. My gut feeling is to set it back about one inch. Thanks

My most recent Twister uses stock moments. Power is an FP40 with a tongue muffler. Front end was not cut back. Engine as far back in the cutout as possible. Very quick turn, responsive airplane. To slow and smooth response I'm using a small combat style handle. The wing was built with tips and half ribs. The tail moment was not lengthened or "Fancherized".

Plane is working very well. My preferred comp plane at the moment. My scores have crept up to the mid 400s in local meets. The plane can definitely do better. (Probably I can too, might only have 30 flights or less on the combo.)

IMHO...Depending on what type fuel tank you are using...size and style...mount the engine close to the tank as possible (allowing for acceptable plumbing)or the tank as close to the engine as possible. During the selection of the position...tack the engine in place with tape or rubber band and check the balance I.A.W. the C/G in the plans. My engine is as far back in the mount, as allowable. I use a clunk tank on my Twister (4oz. Sullivan) and there is very little distance between the engine and the tank. I have no added weight on the nose or tail. I use a Brodak .40 with an aluminum spinner. (Plastic in the picture) My fuel tank is “height adjustable.”
Norm

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>How far back, if any, should an OS 40 be moved on a Twister?
>I plan to build it stock, and it is definately a stunt trainer
>for me. My gut feeling is to set it back about one inch.
>Thanks

You can build the Twister as stock as a rock, and have a very competitive airplane. I have a flying buddy here in the St. Louis area, that used the same Twister with OS FP.40 power to go from Beginner to Expert. Yes, one single airplane! I think he wore out at least two FP-40's along the way, and it was crashed and repaired a couple of times also. The Fancher mods are neat and work well, but the Twister is very effective in stock trim, and how well it flies is directly proportional to how much fuel you burn in practice!
Good luck and have fun,
Dan McEntee

" I have a flying buddy here in the
>St. Louis area, that used the same Twister with OS FP.40 power
>to go from Beginner to Expert. Yes, one single airplane! I
>think he wore out at least two FP-40's along the way, and it
>was crashed and repaired a couple of times also."

Say Dan,

What ever happened to your flying buddy in the St. Louis area???

Tight lines!

Wes

>" I have a flying buddy here in the
>>St. Louis area, that used the same Twister with OS FP.40
>power
>>to go from Beginner to Expert. Yes, one single airplane!
>I
>>think he wore out at least two FP-40's along the way, and
>it
>>was crashed and repaired a couple of times also."
>
>Say Dan,
>
>What ever happened to your flying buddy in the St. Louis
>area???
>
>Tight lines!
>
>Wes

Hi Wes;
I'm talking about my friend John Garrett. John works a lot and spends a lot of time out of town as a result. Doesn't have much time to build, so he makes good use of what he can buy sometimes and with ARFs. He has a Ringmaster that has been around almost as long. The Twister did finally meet an untimely end, and we jumped up and down on the remains so he couldn't beat us with it any more
Dan McEntee

Thank you for the advice. I'll build it per the plans.

My advice is to not move it back at all. I've built at least 9 Twisters prior to 1990, and used a muffled OS-40 FP in them all, with good luck. With a Fox .35, the Twister is capable, but is definitely on the sensitive side for a trainer. The extra weight of a muffled OS-40 FP tends to make the Twister smoother and easier to fly, yet still perfectly capable of doing a good pattern.

One of the very best examples of a Twister for me, in terms of pleasant and capable flying, was a scratch built one with its nose extended by 3/4". It had several other mods, but was a particularly sweet flying model.

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"Twister Sister", with longer nose per Bill Melton's advice

My first complete pattern (if you could call it such) was on a battered Twister which had its nose broken off twice. I had been repaired with 1/8" Lite Ply doublers on both sides of the nose and over the front of the wing. Heavy! Definitely, and the added thickness meant I had to abandon my 1/8" tapered aluminum engine pads and set the engine flat, with no angle. On the same airplane, I also discovered that the rudder should be built flat, the stock offset is excessive and has a bad effect on its trim. That nose-heavy repaired beast was a fine trainer for me, less sensitive, yet still very capable of a pattern.

If you are not building stock, there are many mods to the Twister which help it as a flyer. One of the best is the "Fancherized" Twister, with an extended tail moment, which also accomplishes a similar benefit: the ship is less sensitive and easier to fly, yet has a very strong corner. Other mods are involved, but it demonstrates how different methods can achieve similar results (I believe the longer tail moment is a superior approach).

I highly recommend the venerable OS-40 FP because it is an easy handling engine, smooth, easy to start, and capable of a decent stunt run with only a few tweaks: extra head gasket, smaller venturi (from OS-20/25 FP), larger diameter (11-5) wooden (or APC) prop, and proper "stunt" (vs "RC") fuel with less nitro and more oil.

The Twister remains a very good basic kit design, the only thing I would fault it for are gear and tail wheel mounting (which are fragile) and classic nose construction. Both are standard for most older profile designs and arguably appropriate. One of the best features is the simple wing design which is easily built straight without a jig.

Wail away on the mighty Twister; with a 40 FP, it can be a good stunt trainer.

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"My wife complained to me yesterday that I never take her
anywhere expensive anymore. So I took her to the gas station..." -Bill Morell

I would suggest you move the CG forward to 1 5/8 behind the leading edge. Also move the landing gear forward to keep it in the same relationship to the CG. A stock Twister balanced thusly is rock steady, but still squares and triangles nicely.

Russell.
The Twister you flew here in VA a couple of months ago had a Fox 35 in it. That Twister has been flown with a Brodak 25 to an OS FP 40 in it. All was done was adjust the CG with some tail weight. Go for it and have fun.

John Tate
Norfolk Aeromodelers

Thanks, John. I won't be worried about breaking it if it is mine. Flying over grass instead of pavement will also be easier on my nerves. That black stuff is really hard.

Larry, on your "long nose" Twister did you change any other dimensions like lengthening the tail or anything?

Stock Twisters qualify for Nostalgia. Even weird Twisters (like my Twisted Twister- wing tips, half ribs, recut - cool - profile outline) qualified at 2008 Brodak. Might tighten things up tho for 2009. Stock Twisters, however, will be no problem. If the Nostalgia class continues, compete there, easy class in which to win a plank.

The answer to the "weak gear?" A wing mounted gear, of course..
Norm

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There were several changes, but the fuselage tail moment was stock. The wingspan was increased by 2", and stationary tip flaps were used. I used 1/4" sheet for the stab, elevator, and rudder. The nose had the 3/32" birch plywood, maple mounts extending to the wing, recessed fuel tank, gear was imbedded inside, fitted with wheel pants.The tailwheel wire was mounted in a "ditch" in the fuselage, which was filled with epoxolite. Light ply wing tip ribs, fitted with adjustable leadout and tip weight box. Much of the "Better Profile" stuff.

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"If hard work were really a virtue, then mules would be saints." -James D. Richardson