Steps to scratch build a VW

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

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  1. Sep 5, 2019 #541

    fly2kads

    fly2kads

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    I have it, and no, it does not cover the flywheel drive version. I think they include an addendum with their flywheel drive kits that covers the differences. It's still a worthwhile manual, as it covers aircraft-specific ignition and accessory installation, among other things. I still would like to get their separate baffling manual.
     
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  2. Sep 6, 2019 #542

    Pops

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    Yes.
     
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  3. Sep 6, 2019 #543

    BBerson

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    I got that manual at EAA Airventure store for $15
     
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  4. Sep 6, 2019 #544

    Vigilant1

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    I have the book and think it is very worthwhile. Yes, there's great info online, but the info in the that manual:
    1) Explains things step by step, in order.
    2) Is correct. There's good and bad advice online. Sure, there may be some tricks or slightly better ways to do this or that small thing, but the directions in that book will result in a solid engine.
    3)Is internally consistent. If a newby follows a bunch of random tips, some will conflict with others.
     
    Last edited: Sep 6, 2019
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  5. Sep 6, 2019 #545

    103

    103

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    I recommend Both the GP manual and Rex Taylors book.
    http://vikingaircraft.com/engine-choices/
    Write Robin Taylor at the link above.
    Read everything Bob Hoover wrote.
    http://bobhooversblog.blogspot.com/
    The remember as Bob always cautioned "You are the mechanic in charge..."
    Buy the resources available (GP & Viking Aircraft, quality specialty tools to build maintain your engine. Since installing the flywheel is not a every year thing this type of tool is good to borrow. If you are not handy with tools Scott Casler @hummel is your best bet today just plan 7 months out for a engine.

    Also not GP has some useful guides on the website. While I have a Hapi case all other parts we GP sourced including the flywheel dynamo housed withing.

    I referenced http://www.greatplainsas.com/imagtime.html
    and it is a good thing. We made up a new spacer to adjust interaction of the mag and the phenolic drive puck. Originally made it solid alloy until I read the Note about the the paper gasket for a thermal break. With a little help from a RV builder with a lathe the adjustment was made and I timed it with a new tool acquired from Wag Aero. In stock and arrived in 2 days. Great stockist for odd stuff. Rebuilt my Maul tailwheel with Wag Aero parts. Great company but I am digressing from VW... to recover everyone should have at least one Magneto on a VW and own one of these timing lights.
    https://www.wagaero.com/maintenance/tools/magneto-tools/synchronizer-w-tweeter.html

     

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    Last edited: Sep 6, 2019
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  6. Sep 6, 2019 #546

    103

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    Yes most single seats and some well designed 2 seats make good use of VW. The Key is staying within the limits of operation. My heads approach 390f as I climb to 3,500ft+ on a 95f day. As soon as I am in cruise configurations heads settle to 330f. The key to a reliable VW is matching good parts, assembly practice and a plane that does not need more than 45hp for cruise. Mine is about 37hp in cruise based on fuel burn mp and rpm. I am not expert just building on the successful ones who have gone before. Continuous 65hp and up is asking for trouble. The Sonex on a hot day 2 up struggles with a 2180. The Cygnet with a large wing, clean lines does not struggle on a hot day in cruise. Flys very well if kept lite on a 1834cc and if you like the creature comforts like a starter overbuilt gear with Cleveland Wheels a 82mm stroke variant offsets the extra weight just modify the climb out to match the day at hand.
     
    Last edited: Sep 6, 2019
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  7. Sep 7, 2019 #547

    Bill-Higdon

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    One book I haven't seen mention is Bill Fisher's "How To Hot Rod VW Engines" it's very much in the style of Bob Hover, he tells what works, what doesn't & I can say his use of the cut off ends of old VW push rod tubes to keep the oil from flowing into the rocker arm covers works very well.
     
  8. Sep 7, 2019 #548

    Pops

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    "Hot Rodding" a VW engine is going 180 degrees in the wrong direction. Great for a high rpm VW street car, wrong direction for an aero-VW engine.
     
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  9. Sep 7, 2019 #549

    dmar836

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    103, You hit on the slippery slope in your last post. One can’t simply adjust V-speeds by using a higher HP engine build to compensate for weight which was never in the original design. That is, not without changing the designer’s wing loading and many of the flight characteristics. What scares me is when we “improve” to the point of now having an airframe that is no longer sufficient structurally.
     
  10. Sep 7, 2019 #550

    103

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    The climb is marginally improve with additional CC. I cruise with about 40hp and have no intention of overspeeding the airframe. Bigger is not always better Dan Sisler does recomend exceeds ok ng 1834cc had prop VW for weight reasons. He did install a Jab2200 in the prototype at Viking Aircraft and it fly well without the extra 40lbs and vw with starter and dual ignition equvalent.

    As Dan "Pops" points out the bigger VW is only 2lbs more than 1834cc. The extra weight comes from adding batteries, dynamo, starter and secondary ignition.

    The Cygnet should be flown within the original weight parameters set forth by the designer.
     
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  11. Sep 8, 2019 #551

    Bill-Higdon

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    I'd say yes as far as "Hot Rodding" the engine, but it includes things to make any VW engine last longer
     
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  12. Sep 8, 2019 #552

    Pops

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    That is true. But, for someone that doesn't know VW engines, its going to be hard to pick out what they need for a longer lasting aero engine. That is where reading Bob Hoover's Blog and the GP's manual will help.

    https://www.scribd.com/document/294986137/vw-aircraft-engine-building-bob-hoover
     
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  13. Sep 8, 2019 #553

    dmar836

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    I think this thread might have run its course for me. Go build!
    Dave
     
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  14. Sep 10, 2019 #554

    fly2kads

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    A new VW engine building book is on the market:
    https://www.cartechbooks.com/how-to-rebuild-vw-air-cooled-engines-1961-2003.html

    I picked up a copy, 'cause I'm nearly as bad about buying VW books as I am airplane books. It just arrived today, so I have only given it a first pass through. It looks like a good addition to the library! The book covers a tear-down and rebuild of a stock motor. The process is well illustrated with color photos, a nice improvement over older manuals. The book includes some helpful hints and repair procedures along the way. Even in a first pass, I have spotted a few procedures that are a little different than what I learned in my previous VW build, so it will be interesting to learn alternate methods. The book is directed to automobile usage, but it will still be very helpful to someone building an aircraft engine.
     
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  15. Sep 10, 2019 #555

    Marc W

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    There is a Sonex builder in my EAA chapter. He has over 500 hrs. on the Sonex and he has been a great resource for me as I got my VW dialed in.

    The original heads on his Aerovee engine were from Mofoco. He always had valve sealing problems with the Mofoco heads and had to have the valves redone periodically. He recently got a new set of heads from Aerovee. Whoever he talked to at Aerovee told him the quality of the Mofoco heads is spotty. Some are fine and some are like the heads my friend has. Aerovee is now using Empi heads. My friend has a few hours on the Empi's now. He picked up some HP with them because the engine turns faster now and the temps are higher. He is currently trying to get his temps lower and is changing props to load the engine more. The Empi's must have a smaller combustion chamber. He originally built the engine with a 7.5 CR. His home airport is at 5000 MSL so a little more compression is a good thing. Time will tell how the Empi heads work out.

    I should add that the problem with the Mofoco heads was that the valve seats would go oval. I don't remember exactly but I think he said a valve job would last about 150 hrs. His CHT's were good with the Mofoco heads.
     
    Last edited: Sep 10, 2019
  16. Sep 10, 2019 #556

    Little Scrapper

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    It hasn't even started! Just hang tight, I'm buying a case this week and things will get back on track here.

    It's been interesting so far. I haven't commented in the last couple pages because of lack of experience but I'm very much on track.

    Fuselage is going together and case being purchased this week hopefully if I can get away for a little bit.
     
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  17. Sep 10, 2019 #557

    dmar836

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    Lots of great tips but the theoretical “I would...” additions water it down. Just surprised we already have over 500 comments. I’ll stay in here but the VW engine page here has lots of hidden tricks. T-intakes vs. castings, etc. that pops and a few others have contributed. Like you guys said early on, difficult to get it all in one spot.
    Dave
     
  18. Sep 10, 2019 #558

    dmar836

    dmar836

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    On the third iteration of the rear bulkhead of my fuel tank. When done, I’ll resume the engine build
    D38E3D0D-5634-4354-858F-5DDE56D813E4.jpeg C8FFCD0C-2D7B-4392-8141-1282FF4D75CF.jpeg B77DEA86-31CA-4938-A6D4-CCE8BC4DD57F.jpeg C78F45B9-9657-4B74-9354-C673ABDD2E38.jpeg
     
  19. Sep 15, 2019 #559

    Pops

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    DSCF0009.JPG Drilled lighting holes in the flywheel drive VW bed mounts. Total weight is 830 grams or 1.83 pounds. Hope I can build the flywheel drive engine and not be heavier than the 141 lbs total firewall forward weight of the pulley drive 1835 cc engine on the SSSC.
     
  20. Oct 16, 2019 #560

    Hot Wings

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    Ran across these YouTube videos today after following a Cygnet link here on HBA. Thought they might fit well with this thread:



    Tp IV in the opening

     

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