Enclosing an Evans Volksplane VP-2

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by cluttonfred, Oct 26, 2014.

  1. Oct 26, 2014 #1

    cluttonfred

    cluttonfred

    cluttonfred

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    I have always liked the VP-2 but it's a bit of an odd bird, quite big for a single-seater but not quite wide enough for a real two-seater. The photos of the original flying two-up show the passenger with an arm literally around the pilot's shoulders. That actually fit the original design brief, which was a successor the single-seat, open-cockpit VP-1 big enough to take a friend up for a short hop.

    Of course, builders are always looking to "improve" the design which means there have been dozens of different cabin/canopy modifications to the VP-2. Below are a few that I like, but the problem with all of them is that, by enclosing the previously open cockpit, you have reduced shoulder room from infinity to the width of the fuselage and made it even more cramped flying two-up.

    I have been scheming some tricky cushion arrangements to provide staggered seating when flying two-up, and I can easily imagine a removable or convertible canopy or cabin top to fly enclosed when solo and open cockpit when two-up. But neither is a real solution to the basic problem. I'd rather not have to widen the fuselage because of the changes that would then cascade through the whole design.

    Does anyone have any suggestions and/or inspirations on how you might enclose the VP-2 cockpit in a way that maximizes width at the shoulders without looking hideous?

    Cheers,

    Matthew
     

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    Last edited: Oct 26, 2014
  2. Oct 26, 2014 #2

    cluttonfred

    cluttonfred

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    OK, responding to my own thread, but here is a possible inspiration, the WWII Malcolm Hood on a Spitfire Mk IX and a P-51B/C Mustang.

    detail_spitfire_ix_28.jpg MalcomHood1.jpg
     
  3. Oct 26, 2014 #3

    skier

    skier

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    Bowers Namu II

    namu.JPG
     
  4. Oct 26, 2014 #4

    fly2kads

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    Sorry, Matthew, but the VP-2 is one small step from hideous, as it is. (Part of it's charm!)

    I think the Malcolm hood idea is a good one. My other thought would be to use the arrangement on your French example above, and bulge out the side windows in a similar manner. I think as long as the bulge isn't too extreme (say 2.5 inches or so), it wouldn't look out of place.
     
  5. Oct 26, 2014 #5

    billyvray

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  6. Oct 26, 2014 #6

    BBerson

    BBerson

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    If the bubble is bulged enough, you could lean your head over and look straight down. Cool!
    Just like the heli-loggers do.
     
  7. Oct 26, 2014 #7

    Wanttaja

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    I like the staggered seating concept (like a DH Mosquito) but don't think you could do it on a VP-2 as the bulkhead behind the pilot seat is structural.

    Tandem is then your only option...perhaps with a "wide stance" for the passenger (Minnesota folks should get the reference) to get his feet on either side of the pilot. However, the stock opening in that bulkhead is pretty small. Plus, you don't want the pax to be too far aft (due to CG) and the wide-legged seating position might well be too uncomfortable.

    The solution, I think, is an *aft-facing* passenger seat. It puts the passenger's center of mass much closer to the CG, and gives him a pretty good bit of legroom. You could even narrow the fuselage a tad, vs. the stock VP-2, because you won't need all the extra width.

    It would mean the plane couldn't be used to check out a potential builder or purchaser, but it would give good comfort.

    Ron Wanttaja
     
  8. Oct 26, 2014 #8

    cluttonfred

    cluttonfred

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    Thanks, all, keep the suggestions coming. I have also been trying to figure out how to include the slick forward-hinged arrangement of the Gardan Mincab.

    8665996026_d1ea31dd61_o.jpg

    billyvray, I have not given up on the Pataplume 2, just too many planes, too little time, I want to build them all.;-)

    PS--Ron, our posts must have crossed in the ether. I still think the staggered seating has merit, notice in the drawing in my first post above that the seat back is actually several inches forward of the rear spar bulkhead. Nice out of the box thinking on the rear-facing seat, but that's not for me and a tandem would put the CG too far back for safety without a major redesign.
     
    Last edited: Oct 26, 2014
  9. Oct 26, 2014 #9

    Wanttaja

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    No, I wasn't clear, I was responding to your staggered-seating suggestion. I didn't think of moving the pilot forward, vs. the pax aft, since I traditionally have problems with legroom and wouldn't consider giving up any.

    Friend of mine with a VP-1 (actually, a Porsche-Plane) isn't very tall, but his seat is back all the way. I'd be surprised if the VP-2 was any better.

    Well...shoot, Matt, it's not YOU that would be riding there, would it? :)

    Conventional tandem would certainly mess the CG all ta heck....that's why I suggested backward seating. If you absolutely MUST carry one of those worthless noisy meat-bags, put him in facing backwards so his yells of delight (aka "screams of terror") are aimed away from you. If a passenger wants a comfortable, roomy seat, put him in a lawn chair next to the hangar so he can wave at you as you climb away.

    Why...yes, I *have* flown single-seat aircraft almost exclusively for the past ~28 years... :)

    Ron Wanttaja
     
  10. Oct 26, 2014 #10

    skier

    skier

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    Or like the Kellett (YO-60?) Autogyro

    Kellett YG-1B.JPG
     
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  11. Oct 26, 2014 #11

    cluttonfred

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    LOL, Ron. My thinking on the staggered seats was that the pilot should be forward of the passenger for elbow room when flying. Basically what I had in mind was a 1" backrest all the way across with a vertically-split 3" pad on top of that secured with Velcro. Two-up, you detach the right side pad, flip it over and out it on top of the left side pad. So now you've got the pilot moved forward 3" and the passenger moved aft 3" but still with the 1" backrest for a total of 6" of stagger, hopefully enough for a little shoulder overlap. The seat harnesses would use clips for the fittings below the waist to allow rearrangement as needed.
     
  12. Oct 26, 2014 #12

    FritzW

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    I like the "hard top convertible" approach, or maybe something like the old "T" tops.

    [​IMG]
     
  13. Oct 26, 2014 #13

    TFF

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    The funny thing about width of two seaters is the widths are not all that different. If I am not at the controls of a C150 or a Grumman AA1 or Ercoupe, I put my arm around or at least behind the other seat. I measured a 150 and a RV7; the same. Where the cabin curves is where comfort comes in; shoulders sticking out in the VP-2 is probably not too bad if you are not skittish about flying. Getting in a VP-2 means you are not skittish about flying. The red one with the sportscar removable hard top look would be OK. As for too many airplanes to want, everyone has that even Kermit Weeks. I narrowed two out and both are possible to do in this lifetime. Real, finishable, vetted. They are complete opposites; one a parasol one a speed traveler. I study the plans so I know them. They are not perfect airplanes; none are. Marry a design and let the other pretty girls walk on by.
     
  14. Oct 26, 2014 #14

    FritzW

    FritzW

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    That's the only way to get one built.


    Matthew,
    Get engaged to the VP-2 and we can throw around some ideas on how shave 100 pounds off her before your wedding night;)
     
    Last edited: Oct 26, 2014
  15. Oct 27, 2014 #15

    cluttonfred

    cluttonfred

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    Thanks, all. Fritz, the VP-2 and I are engaged but as I expect to divide my post-retirement time between Europe and the USA I expect that I will be guilty of bigamy, likely with the French design in the USA and the American one in France or the UK.

    I'd love to hear some of your ideas for shedding weight from the VP-2. I have been thinking of some ways to do that (Oratex fabric, composite landing gear bow and tail spring, Asuza nylon wheels, Nikasil engine cylinders, etc.). Maybe even spruce/ply box spars instead of planks? I am quite sure you have some insight that I don't have from all your VP experience.

    As I just wrote in response to a post on the 21st century Volksplane? thread, I am beginning to think that the ultimate VP-2 would actually be in the "less is more" category, sticking to the original bare-bones, open-cockpit design and rejecting any modification that would add rather than subtract weight. Doing that and installing a 2100-2300cc hand-prop engine would provide a safer and more enjoyable aircraft with adequate performance two-up and quite impressive performance solo.

    In my case, I'd be looking to fit the VP-2 into the European microlight category, and it just so happens that the 450 kg + 5% (472.5 kg 0r 1042 lbs) maximum gross weight allowed with a ballistic parachute would exactly match the VP-2. With the original open cockpit, that ballistic chute would fit perfectly in the fairing behind the rear spar bulkhead.

    Cheers,

    Matthew
     
    Last edited: Oct 27, 2014
  16. Oct 27, 2014 #16

    FritzW

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    Matthew,

    Congratulations on your betrothment.

    A few thoughts I've had on lightening up a VP-2...

    Make it 26" wide, throw another (very light) bulkhead 30" aft of the aft spar bulkhead, build a Pietenpol'ish rear cockpit, put a KR engine mount and a RevMaster 2100D on it. ...but that's another story;)

    1) cut away all the dead weight from the firewall and skin it with 1/8" ply. Kind of like this: firewall.jpg
    2) do the same with the stern post
    3) do sort of the same thing with the spar and strut carry throughs. Skin them with 1/8" instead of 1/4" and use 1/8" doublers where needed (I've sorted that out for the VP-1, the VP-2 would be a little different)
    ...kind of the opposite of this: 100_2890.jpg 100_2897.jpg

    4) cut lightening holes in the 1/4" ply cockpit floor, use 3/4" foam under the floor so you don't make dirt collecting pockets (I'd need to sketch that for it to make since)
    5) replace the seat support with a Warren/Pratt truss made out of 3/4" square Pine with 1/16" ply gussets
    6) make the seat out of 2 pieces of 1/4" ply laminated together, cut lightening holes in the bottom piece.
    7) clean up the bottom rudder bushing mounting ply, there's no need for 3/4" ply there. I think 1/4" ply like the top mount glued to little wedges (we'd have to look at the loads)
    ...but if you use 3/4" ply lighten it up something like this: 100_3146.jpg (you could shave a few ounces off the rudder tube bushings and get rid of the bolts)
    8) replace the F-15 ply web with 1/16" ply with 1/16" ply doublers around the slot and holes.
    9) use 15" rib spacing and nose rib on the wing (like the VP-1)
    10) make the ribs out of 1/4" sticks, or 1/8" ply and cap strips like my "quick built wing". If you use 1/4" ply do the lightening holes like a truss.
    11) use old school routered spars (hand router and templates) ...or built up spars like your thinking
    12) make the ailerons one bay wider and few inches shorter in chord. Build a light false spar out of 1/16" ply and 1/2" Doug Fir sticks (more for better handling than weight saving)
    ...sort of like this: Wing Idea VP-1.jpg
    13) use a "C" beam spar for the ailerons, 1/8" ply or 1/4" stick ribs
    14) OTS aluminum trailing edges
    15) cut lightening holes in the top two bays of the rudder tube, built up anti-servo tab, lighter rudder ribs
    15 a) get rid of the rudder rib bolts, or at least use Nylon bolts
    16) routered or built up spar on the stabilator, lighter ribs
    17) lighten the stab up as much as possible aft of the hinge so the counter balances can be lighter, use an ultralight antiservo tab like this one: VP-1 UL antiservo tab.jpg
    18) maybe use a single stab counter weight inside the fuselage or move the stab weights to the inside of the stab leading edge (I did that on my OpusII, didn't save weight but was much cleaner)
    19) tube steel landing gear (or composite like you said)

    There are more ways to lighten a VP-2 but that's what comes to mind right now. As soon as I hit the Post button I'll think or three more:)
     
    sotaro, cluttonfred and Himat like this.
  17. Oct 27, 2014 #17

    cluttonfred

    cluttonfred

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    Thanks, Fritz, some great stuff in there. I'd be nervous about some of the more aggressive structural changes but there is a lot I'd be happy to do--seat, seat support, lighter ribs, lightening holes where things are needlessly hefty. On that firewall mod, I can see making a few lightening holes but would worry about taking away too much with the engine bolted directly to it. I have thought about the aileron change but would probably stick with simplicity there. I have often wondered why Evans went with the aluminum anti servo tab, any idea why?
     
  18. Oct 27, 2014 #18

    FritzW

    FritzW

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    I don't know why he made it out of sheet. It's a big problem for guys that don't have access to a brake. ...the aluminum one is light though
     
  19. Oct 28, 2014 #19

    Wanttaja

    Wanttaja

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    Out of curiosity, Fritz, what's the story behind this? I presume it has the same area. Does the narrower chord reduce stick pressure?

    Ron Wanttaja
     
  20. Oct 28, 2014 #20

    Turd Ferguson

    Turd Ferguson

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    Fritz is more qualified to answer since he built and flew a VP, but the most common comment about the ailerons on a VP is they are heavy. Bud Evans knew this but in the interest of simplicity, mounted the ailerons directly to the rear spar. I have wondered if just moving the hinge line aft would lighten up the ailerons?
     

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