Steps to scratch build a VW

Discussion in 'Hangar Flying' started by Little Scrapper, Aug 13, 2019.

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  1. Aug 20, 2019 #181

    Pops

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    And the one's that can fudge the rules without getting caught are the winners in any racing.

    When NHRA drag racing went to Bracket Racing, I quit. I don't like socialized racing.
     
  2. Aug 20, 2019 #182

    Pops

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    I prefer minimum rules and more of a free for all. Want to be free to do my best.
     
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  3. Aug 20, 2019 #183

    fly2kads

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    FYI, the rules posted are good for historical interest. Ed Fisher has a revised set of rules available under the Supervee banner. The original rules for a 1600 class are largely unchanged, but he has added two classes: one for engines up to 2180, with only a few restrictions; and an Unlimited class that is pretty open. If there is enough interest to hold races, there will be lots of options available.

    Edit: the flexibility is in the engine specifications. The airframe rules are common across classes.
     
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  4. Aug 20, 2019 #184

    Little Scrapper

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    What other engine rules exist? Of is it just CC's?
     
  5. Aug 20, 2019 #185

    Hot Wings

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  6. Aug 20, 2019 #186

    Vigilant1

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    Interesting that, in the old rules posted by TFF, metal props are not allowed, except on planes that were using them in 1985, and which haven't had a change in ownership.

    I'm sure they give a competitve advantage, but GP and most others specify only wood props are to be used. Revmaster allows "non-wood propellers," and are still set up to provide oil pressure for a controllable pitch prop. In general, the light weight and (especially) the vibration damping characteristics of wood make them much preferred for safe operation on VW-based aircraft engines.
     
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  7. Aug 20, 2019 #187

    Vigilant1

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    And tractor only--no pushers need apply. When I glanced through the rules, they provided restrictions for the engine, but I did not see a specific limitation against having more than one of them. I'm sure it's in there somewhere, clearly, single-engine was the intent. But if this is a loophole and a mini Wing Derringer with two 1600cc engines showed up on race day, there would have been a scene. And, without the pusher prohibition, the Beetlemaster would have been there, too.
     
  8. Aug 20, 2019 #188

    dmar836

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    New rules are available to members of SV. Not sure Ed wants spit ballers but if people are serious....
    I’m kinda of surprised more guys haven’t stuck with us in SV. So many Sonerai available out there for a song.
    I suppose bench racing has become an even more popular alternative now with the internet.
    Looks like there will be at least two of us!
    Dave
     
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  9. Aug 20, 2019 #189

    Richard6

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    Well sometimes the rules have loopholes you can drive car thru. Yes, Yes I know, this is a airplane forum, but I have to relate this story.

    There is a guy from Michigan who builds formula race cars. Small ones that weigh about 800 to 900 lbs and use a snowmobile engine of 500CC twin cylinder, water cooled.

    The rules were very specific about what engine could be used and what modification could be made. (read that as none) But the rule book did not say anything about the position of the engine. At the time, the engine was place behind the driver with the exhaust facing forward and curving up around the engine and then pointing out the back of the car.

    Well this place some restrictions on the tuned exhaust system, so the car builder turned the engine around so that the exhaust was facing the back of the car which allowed better exhaust tuning. He had to use a set of gears to make the output turn the right way to drive the rear wheels.

    He showed up at a race and the tech people went nuts. "YOU CAN 'T HAVE THE ENGINE FACING THAT WAY". So he drags out the rule book and ask them to point out where it said that. Well it didn't.

    The car only raced one time before the rules got changed !

    Sometimes you have to see what is not there.

    Richard
     
  10. Aug 20, 2019 #190

    dmar836

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    Okay. Let’s build!
     
  11. Aug 20, 2019 #191

    Hot Wings

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    Why just the members? I'd like to see a copy of the rules to see if I'm even interested in becoming a member.
     
  12. Aug 20, 2019 #192

    dmar836

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    Well, I guess that’s how SV knows you are interested. It costs money to print the rules and mail them out and a crap ton of typing to post them here or elsewhere.
    It’s old school. That’s what makes it cool IMO.
    I guess this should actually be in a different thread. There was one started years ago about affordable air racing. We’re getting off topic here.
    Dave
     
    Last edited: Aug 20, 2019
  13. Aug 20, 2019 #193

    Pops

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    BeetleMaster, Now you tell me. I must be slipping in my old age to not think of the BeetleMaster. Shrink it down to the bare minimum, single place, fuselage just wide enough for my hips and shoulders, wing area down, etc, etc. Yep, and I have lots of 4130 tubing, 3-- 1"x6" Douglas fir boards 20' long. Enough parts to built the 2 engines, etc.
    That is all I need , another project. It has to be a sickness for sure. :)
     
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  14. Aug 20, 2019 #194

    Little Scrapper

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    On vacation on the beach here and continuing my study on building a motor I came upon a few discrepancies. Keep in mind, I'm use to small block Chevies and motorcycles so I'm a bit tainted.

    Is it true there's no head gasket? I see some copper gasket/shims and even a paper one both of which I'm familiar but there's guys using no gaskets?

    Can someone lay this discussion out for me so I can put this in my notes because I'm a bit confused.

    Thanks
     
  15. Aug 20, 2019 #195

    Hot Wings

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    Old school is cool - to a point. Once typed into Word it's just a click or two to post them electronically. There are even free sites to convert to PDF format
    I don't go to craft fairs and the like that charge me to get in the door to see if there are any vendors with wares I might be interested in buying. Same concept applies here.
    Cast a broader net and we might actually get enough interest to see some planes fly?

    You are right about this being off topic here. Maybe the moderators will move these racing related posts to one of the other threads?

    https://www.homebuiltairplanes.com/forums/threads/cheap-air-racing-class-to-promote-aviation.19521/

    https://www.homebuiltairplanes.com/...-the-cheap-air-racer-discussion-thread.19735/
     
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  16. Aug 20, 2019 #196

    TFF

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    Its fun to have open rules. You can not afford them. Innovative people do well in racing. That is until the money can buy lots of innovative people to put up against the ones playing the old way; one on one. Square wing Cassuts vs tapered wing "Cassuts" vs Nemosis. Progression of spending money. Do you want to beat someone because you are better at flying or better building? Classic problem for all contests. One of the best lines in "Grand Prix"(1966) "Everyone wants to win, there is no distinction in that"
     
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  17. Aug 20, 2019 #197

    TFF

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  18. Aug 20, 2019 #198

    Vigilant1

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    I frequently need to remind myself that these air cooled engines are different in important ways from water cooled blocks and heads. Not just much higher temperatures, but higher temperatures differences from head to barrel and across the head. Add in the differential expansion of aluminum and steel and it is quite a lot of stuff going on. Different things work.
     
  19. Aug 20, 2019 #199

    Hot Wings

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    VW did at one time use head gaskets. I think 40 Hp gasket kits still come with head gaskets? They were a bad idea and a source of head leaks. The 40 Hp 83mm big bore kits, in my experience, had no head leak problems. There were no gaskets for those cylinder sets.

    Copper may sound like a good idea but annealed copper has a yield of only 4800 psi. A242 aluminum alloy (what VW used in the FI heads) has a yield of 18,000psi in as cast condition, more if heat treated.

    When we torque a head in place the only load on the materials is from the stretching of the head studs. If done in stages it takes care of the compression of the gaskets and everything is in equilibrium.

    Then we run the engine and it gets hot. This adds load to those gaskets due to the difference in thermal expansion of the steel head studs and the aluminum head. This is why only the lower/longer head studs on a VW tend to pull the threads and why the 911 has it's head nuts so far down the casting.

    This is all fine if the materials in the load path have enough yield strength to not move - either by crushing or creeping. Paper, paint,silicone and copper will all do one or both under enough load. The VW contact surfaces at the head and case are quite small in comparison and get even smaller with a large bore cylinder. The best we can do is straight steel to aluminum contact. This is done using lapped head surfaces and just enough gasket/sealant to fill up the machining marks on the base that are big enough to let oil past. Aluminum alloys start to loose strength at high temperatures. High in this case being around 350F or so. If the load from the extra heat expansion and the lowering strength change enough the aluminum will yield, or crush. Then when cooled there is no longer enough clamping load to keep the head securely on the cylinder and things start to move in service. This is how VW head leaks start.
     
  20. Aug 20, 2019 #200

    dmar836

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    Hotwings, makes sense. So we do go ahead and use the copper as a stopgap measure to protect the aluminum?
    Dave
     

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