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Steps to scratch build a VW

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TFF

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My guesstimate is the extension is about 12”. What do the plans say or is there options on the plan?
 

dmar836

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The plans from Aircraft Spruce have nothing firewall forward. I have never seen a set but you know SJW's plans would have been complete with lots of notes. A member over at the Affordableairracing.com generously sent me a scan of the hub and shaft drawings for reference a few years back. No cone drawings that I recall. I can't find them on my hard drive now! They had lots of little notes and changes.
Dave
 

Little Scrapper

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Plans are available for the prop extension from Aircraft Spruce. It's a separate item you buy and the part number for the drawings are on the plans when they ship.

I have not ordered them yet because I've been focused on the fuselage.

This is currently available on Craigslist for $1,300.

Screenshot_20190815-223741.png
 

Pops

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I don't know, but I don't think ready-made items like the Force One hub were available when Wittman was laying out the V-Witt. So, the (stock) flywheel end pulley was the stronger of the two (stock) options available, and he went with it to drive the prop. I'm not familiar with his engine, but I'm assuming that, to accomodate the sleek cowl profile he wanted he chopped off at least the top of the transmission mounting flange at the back of the engine, then designed his prop extension.

Mounting the prop on the pulley end and using a Force One bearing and hub gets the prop a bit farther from the case--maybe you could still be faithful to the V-Witt cowl lines without any prop extension at all if you used a big spinner?





I'm afraid I don't know that one. It's not as famous as Steve McGarrett's "Book 'em Dano, murder 1."
When I get the time, been thinking of welding up a little larger rectangle oil sump at the bottom of the engine and run the intake (Look at engine drawing above) in the middle of the box with a 90 degree down outlet to a carb flange on the bottom for the up draft Zenith carb. No oil lines for a hot oil box above the carb on the intake and a slightly larger capacity oil sump. I always use a small sump with an extension to the oil pickup tube, so not to unport the oil pickup tube in a hard slip. Have had good handling street VW's that you could easily unport the oil pickup tube in the sharp curves on a mountain road. Simple with less parts. Two birds with one stone.
 

dmar836

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Looks that way, doesn't it? The flange of the cone is thick but the rest is about 3/16" His plane was reportedly 450lbs. If I managed 500lbs I'd be happy.
You can see his cone was welded aluminum(I mispoke earlier about steel) and looks to be a lot lighter than the casting I have. His landing gear was also thin and of titanium. He knew how to build light!

upload_2019-8-19_13-33-51.jpeg
 

dmar836

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Little Scrapper, Great to see parts out there but, honestly, those are the kind of things guys give to other guys. In today's world though everyone thinks they are a picker.
My extension shaft is undersized at the carrier bearing- maybe from the machinist missing what is called out as a "critical dimension" or from being slapped about by harmonics. This one could be as well. Again, a pig in a poke and I don't throw money at the gambling table. For good money I expect nice parts, not scraps. My whole project was $200!
If those are the prices people want I would seriously buy a cheap Sonerai project or build a Lasher Renegade if you just want to be obtuse. Ed usually knows where good projects are and might even have one partially done now!
Dave
 

Vigilant1

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This shows the orientation of the engine with the cone and extension shaft in place. Transmission flange is all there.

View attachment 87942
I am sure (uninformed) folks say this all the time, but here goes:
1) Boy, it sure looks like it would be easier and lighter to make a front bearing support out of 6061 tubing than to make that cone. Would the weight be much different? Inspecting the engine's flywheel bearing and the back side of that prop bearing would also be easier with an open frame.
2) Can the aerodynamic benefits really be worth the hassle and weight? The angle from firewall to the tip of the spinner could be just as narrow with a large spinner. Yes, the prop disc is closer to the engine, but the inner part of the prop disk hardly moves any air anyway, so I wouldn't think it would impact total prop efficiency very much.

Maybe this is one explanation for why there are more Sonerei's out there. On the race circuit, how did the Renegade, the V-Witt, and the Sonerei stack up?

No criticism of Steve Wittman intended--he's a better airplane designer and builder >today< than I'll ever be.
 
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Little Scrapper

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Little Scrapper, Great to see parts out there but, honestly, those are the kind of things guys give to other guys. In today's world though everyone thinks they are a picker.
My extension shaft is undersized at the carrier bearing- maybe from the machinist missing what is called out as a "critical dimension" or from being slapped about by harmonics. This one could be as well. Again, a pig in a poke and I don't throw money at the gambling table. For good money I expect nice parts, not scraps. My whole project was $200!
If those are the prices people want I would seriously buy a cheap Sonerai project or build a Lasher Renegade if you just want to be obtuse. Ed usually knows where good projects are and might even have one partially done now!
Dave
I didn't say I was buying it, I just said it was for sale.

I'm building one, I have no interest in buying parts
 

dmar836

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Dunno. He did things differently than everyone else. He was also the most winning air racer of all time so...

"'Easy" then is different than "easy" now. If one can't find it in a catalogue now, it's a useless proposition.
 

dmar836

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I didn't say I was buying it, I just said it was for sale.

I'm building one, I have no interest in buying parts
Oh, I know. Wasn't digging on you. I see this alot with hot rod parts and in many other hobbies. Get in with the right fellows and things are given away and traded. On the web, people will ask a ton and say they aren't even sure what it is. In this case I couldn't see what all was there. Maybe dual mags? Parts aren't from one project - that's a sign. Maybe hangar clean out time?
Dave
 

Pops

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Steve Bennett's article on VW crankshafts used to be on his company's web site. Read it several years ago. I have 2 more forged VW German made 69mm cranks that I can use if I want to build another 1835 engine. VW never made cast cranks, the cast cranks are after market made. For a bullet proof 1835 cc engine, I will go with the Force One main bearing and use a wood prop and never worry about a broken crank. Steve said it was over kill, and I think he was right, but I like overkill in an aircraft. Just like the G rating in the airframe. Like Steve said in the article, even Cont and Lyc can have broken cranks, I know, I was flying a Lyc when the crankshaft broke in 1984. Flew it the 7 miles to a runway with the crankshaft broke in front of the center main bearing. Ran on the 2 rear cylinders and the front 2 cylinder were about 180's degrees out of time firing out of the exhaust ,with the rear part of the crank hitting the front part of the break and tuning the front half and prop.
 
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TFF

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Racing plane, racing rules. http://www.sonerai.net/repository/formula_v_rules.pdf

Plane must weigh a minimum of 450 lb. Pilot must weigh at least 170 or sit on some ballast. Remember racing rules are restrictive to try and make a fair contest. What you can do for racing is completely different than sport flyer. I noticed that the speeds are intended to stay below 190. Weight may be the enemy, but in racing its not a free for all. You have to play by rules.
 
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