I am working on a Fan style twister that I want to modify slightly and can use your opinion.  Currently, I have beefed up the nose with 3/16 birch ply on the inboard side covered with 1/4 balsa.  I laminated 1/16 birch ply to the soft ply included in the kit for the Outboard side.  On the wings I am going to add curved ends (similar to the 59 Ares) and add adjustable lead outs and a tip weight box.  I am not sure if I want or need to extend the Fuse an additional 3" as reccomended.  I will be powered by a Fox 40 Stunt motor.  What are your thoughts on having to extend the fuse?  Needed or not?  Also, I am tossing around the idea of 1/2 ribs on the wing?  Is there an advantage or leave the stock style alone?

   You definitely need to extend the fuselage as indicated in the "Fancherized Twister" article. That's the source of most of the improvement in the performance. It wouldn't hurt anything to make the stab/elevator 10-15% bigger in linear dimensions, either. With a Fox 40 (and version) nose weight will not likely be a problem.

   I am a little concerned about the engine choice - are you sure this one runs reliably on a profile?  Which Fox 40 are we talking about -70's "Large Case", "6-bolt backplate", or the one that looks like a blown-up 35?

    Brett

   

   All that extra plywood isn't necessary. You can add a balsa cheek to the inboard side of the fuse to stiffen the nose up, and put metal pads under the engine mounts to keep from crushing the softer ply that sometimes comes in the kit. Or you can just replace it with good 1/8" birch ply. You'll probably have to add the extended tail to offset the extra weight you built in to the nose, and the extra weight of that engine. I would throw an extra head gasket in the head, and try flatter pitch props for the first few flights, after you are sure the engine is run in properly. No more than a 10-5 to start with, or maybe an 11-4. You can also contact Lou Woolard about taming that beast also. It has been done! I think he even posted the specks and procedure in Stunt News several years back. Gotta love Lou Woolard!
   Good luck and have fun,
   Dan McEntee

Dave,
You can search the members section to fine a email for Lou. Or he may be listed in the PAMPA directory.

Not sure about the 40 but the 35 SOMETIMES has issues on a profile. Gives you burb. The more modern engines do not do the burp. You could get away with a smaller engine. Burns less fuel and might be lighter.
We have a guy in our club that loves the Twister and has built 3 and just bought another kit. He likes the Aero Tiger 36. He also has a Evo 36 on one that is a great combo.
Extend the fuse and keep the plane as light as you can. It's a great trainer!

Dave (and Dan McE) - that's LEW Woolard who does the Silver Foxx 40 small-case, banjo-back rework. (Maybe I'm just sensitive about how the name is spelled: Lewis is British, Louis is French, and down here near the Mexican Border, Luis is Spanish... The origins of the spelling, anyway. Today we aren't tied down so tight. But LEW is the Silver Foxx guy...

(I've heard that he may not be much into computers, so a phone call might reach him easier. He should be in the PAMPA directory.

(He's also seen many years, even more than I have and that's a lot...)

Anyway, I've never seen a description of the Silver Foxx rework  by Lew but there was an article in the Sep/Oct '95 Stunt News by Neville Palmer, which details what Lew said he does.

He retimes the sleeve by turning off a smidgeon (precise amount determined by the engine in your hands) from the underside of the flange to lower the entire sleeve. Then he raises the bypasses to a specific distance from the flange underside just so, and tailors the exhaust port timing just so, to the numbers he has found to work.

He also changes the combustion chamber 'bowl' to reduce compression ratio just so for the desired results.  ...and to reduce the 'squish band' width.

The "timing numbers" work out very nearly the same as I've been using, developed independently, for Stunt 35s since about 1990, by the way. (The Stunt 35 flange is too thin to 'drop' the sleeve sufficiently, so I lower the casting deck, instead.)

He includes break-in, fuel and prop recommendations. His method has created the well-regarded Silver Foxx mod.

Fox did not offer ABC sleeves and pistons at the time, but the operating factors do not change with the metallurgy. It should be just as valid for ABC as for 'iron in steel' Fox engines. The biggest difference may be that a well-broken-in ABC small-case Fox 40 shouldn't need as much total oil, and should live nicely on a 50/50 castor/synth fuel  - like almost all current AB? engines - of about 22% total oil.

I have a copy of Nev Palmer's Stunt News article, and can probably scan it to an Adobe PDF, if you'd like the full deal.  Lemme kno?

Hello Lou

I hope you are doing well, and thank you for the information.  This is the Fox 40 delux ABC.  When I ordered the motor I asked what fuel should be used with this motor and ordered a case of it.  It is the Fox Formula 15.  I am going to take her out today and try a few different tanks on the plane and see what it does.  It never seemed to to work well on uniflows or exh pressure.  Anyhow, I do have two of these I am going to send to Lew.  The last time out the motor sounds great at take off but just had no power.  I will report back later today.  Thanks again