Designing and Building a 1/2 VW Cowling for Quickie Q1

Discussion in 'Half VW' started by tgcastleman, Jan 24, 2020.

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  1. Jan 24, 2020 #1

    tgcastleman

    tgcastleman

    tgcastleman

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    I tried to be as descriptive as possible in the title to make this information easier to find in case anyone in the future is doing something similar. From my research, it appears that the 1/2 VW is the best option for a new powerplant for the Quickie Q1.

    The title says it all. I am designing and building a 1/2 VW Cowling for a Quickie Q1.

    If anyone has any tips or relevant information they could share, I would greatly appreciate it.

    I still have the old cowling that went on a Kawasaki 340.

    I don't have the engine yet. I am purchasing a new engine from Hummel Engines. I'm told their backlog is about 6 months long right now. I would like to design and build the cowling beforehand, if possible.

    Does anyone have a 3D model of the 1/2 vw engine? I could not find one on the internet. I will start the cowling design by developing a 3D model of the engine. I will draw it myself if one does not exist yet.
     
  2. Jan 24, 2020 #2

    Hot Wings

    Hot Wings

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    Been done in the past. A search of the old Yahoo group Q-list - might - turn it up.
    Report was it caused problems with the vertical fin due to turbulence. Not exactly the best thing for a plane that is already yaw challenged.

    If you are set on the 1/2 VW you might want to take a look at the Brox and Jinx Rotax conversion for ideas on how to reinforce the firewall?
    Also in the old Q-list archives is a comment from a guy named Gall about indexing the prop on an opposed 2 cyl engine. It applies to the 1/2 VW just as much as the original Onan.

    If it were me I'd forget the digital for building a cowl. The old school way of wrapping the engine and adding foam/plaster/whatever for a male mold will be just as quick in overall time.

    This guy is doing something very similar with his Robin with a 1/2 VW. You might find his blog worth reading?

    http://robinultralight.blogspot.com/
     
    blane.c and delta like this.
  3. Jan 24, 2020 #3

    Victor Bravo

    Victor Bravo

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    One other thing to consider is that if the cowling is significantly larger for some reason (vertically or horizontally), that might also add to whatever yaw stability issue Hot Wings was talking about.

    Has anyone figured out how to balance or minimize the rocking and thrashing of the half-VW? I saw what had to be done to smooth out the O-100 (also a 2 cyl. boxer), it took a good size built-in counterweight on the crankshaft.

    Also, are you going to have enough prop clearance with the larger diameter that the VW swings? The Q-1 doesn't have a whole lot of prop clearance IIRC.

    Like a lot of people I was really intrigued by the Q1, but I've also heard there are some unpleasant aspects of its handling. Never flown one, but I'd love to.
     
  4. Jan 24, 2020 #4

    lr27

    lr27

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    There must be CAD models of full VW engines out there. Wouldn't it be possible to cut such a model in half?
     
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  5. Jan 24, 2020 #5

    Hot Wings

    Hot Wings

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    Yes, the same physics apply. There isn't as much room inside the VW case for really large counterweights and is why some use external weights on the prop flange. This rocking is the reason to pay attention to the prop indexing if using a 2 blade. It looks like Pete was able to keep everything inside on the O-100. The custom rods and pistons helped as well.

    50 Inch is about the maximum diameter for a Quickie prop with the large gear option. The original prop was 40".

    A 1/2 VW on a Quickie is possible, but not as simple as it might at first appear. I gave up on my 1/2 VW Quickie for some of these reasons, but the OP may have different goals and be willing to make compromises I didn't want to.
     
  6. Jan 24, 2020 #6

    kent Ashton

    kent Ashton

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    Cover your mounted engine in plastic, glue pink syrofoam blocks to the high spots on the engine, then use X-30 pour foam to cover everything. Sand to a pleasing shape until you hit the pink foam. Fill with fast setting joint compound. Sand. Paint with a high gloss paint. Wax multiple times. Glass with two or three layers of BID fiberglass. Two layers will do if you glass some ribs on the inside to stiffen it. You might need a few more layers where the cowl screws will go.
     
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  7. Jan 24, 2020 #7

    tgcastleman

    tgcastleman

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    Hot Wings,

    What exactly made you decide against the 1/2 VW?

    What engine is better suited in your opinion?
     
  8. Jan 25, 2020 #8

    Hot Wings

    Hot Wings

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    No one thing really. The report from the other 1/2 VW builder had a significant impact. Prop diameter limitation was another. I had actually started on a belt reduction to "solve" that problem but life got in the way and by the time I got back to that project I had learned a bit more.;)

    There is no good engine for the Quickie IMHO. Even the Onan was problematic for some builders. I'm intending to use an Inverted Briggs 810 but at the rate I'm making progress you could probably buy a Hummel and go fly before I get mine running on a stand. The need for an engine for my Quickie is what started my down the B+S path.
     
  9. Jan 25, 2020 #9

    Victor Bravo

    Victor Bravo

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    The small block 4 stroke industrial V-twin engines, direct drive, with mild tuning, will likely be a very good fit for the Q1. Lighten the engine up by removing a bunch of junk and the flywheel. BALANCE the engine properly. From everyhting I have read, very mild tuning will yield 33-34HP, almost double the original power of the Onan, with high reliability and a long time between overhauls. You should be looking at very very good fuel economy and much better performance than the original. BBerson and several other guys on this forum have studied these engines a LOT, and they will know which models are better or more easily converted to an aircrafft engine. But the Q1 is low drag, so you can go direct drive, and sidestep all of the cost/weight/fiddling of a redrive.
     
  10. Jan 29, 2020 #10

    Sparrow Hawk

    Sparrow Hawk

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    I installed and flew a Q1 with a 4 cylinder 1915cc VW engine. N2XV-Q1.jpg
     
    mcrae0104, Pops, Victor Bravo and 2 others like this.
  11. Jan 30, 2020 #11

    Victor Bravo

    Victor Bravo

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    That tailwheel looks badass :)
     
  12. Jan 30, 2020 #12

    lr27

    lr27

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    Wondering how much weight the vw added above the standard installation. Also if it really belongs in a thread about a cowling.
    ;-p
     
    Last edited: Jan 30, 2020
  13. Jan 30, 2020 #13

    Victor Bravo

    Victor Bravo

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    I'm wondering how much prop clearance you had in the level takeoff/landing attitude. That photo makes it look like it would not be much. Did you limit yourself to three point TO/LDG ???
     
  14. Jan 30, 2020 #14

    lr27

    lr27

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    Looks like ballast duct taped to the tail boom. I hope that's not exactly what it is!
     

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