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Questions for wing assembly

Posted: Mon Jun 19, 2017 9:30 am
by English Johnny
I've procrastinated long enough as terrified starting wing assembly so I need some advice so I can move on, I'm building the 3 piece built up spar (Jim Wills) wing.

I've read Chris Barley's (UK) wing notes and anything else I can find generally on the subject but still have questions so here is a list below, please feel free to give any other advice also. I'm starting on assembly of the centre section to ease me into the procedure and have machined up wood bearers to build onto so keeping the ribs away from the bench.

Has anyone not used a centre section cutout, how impractical would it be to not use a cutout, I am pretty slim if it helps?
Lastly I cannot find the technical drawings for mods on the website, can someone give me a link to them please?
Best wishes to you all,
    What is the best way to glue the ribs on and how do I square them all up.
    Do I varnish everything before or after assembly and what about the inside of the leading edge wrap.
    I'm going to use the top and bottom gusset plate method to secure the trailing edge, do I just feather in the top of the plates once the trailing edge is secured.
    What is the best method for fitting the leading edge, screw and glue or just screw.
    How do I square up the wing panels, they are too long to trammel I presume.
    I'm sitting the spars on machined wood sections on the jig bench (chord wise), is this sufficient to ensure the wings will be level.

    Re: Questions for wing assembly

    Posted: Tue Jun 20, 2017 11:27 pm
    by taildrags
    John; I have not built or even seen the UK wing spars up close and personal, so my responses here will be generic.

    1. The UK group does not distribute or sell the Jim Wells "UK spar" drawings to builders in the US, nor have I seen them on the web. Perhaps someone in the UK can help you with the technical drawings for the spars. Outside of that, a good resource for all of your questions is going to be Chris Tracy's website. The UK Piet group also has a very good website with lots of photos.

    2. Some builders have gotten away with not having a centersection cutout or "flop", but using extended cabanes will really help if you decide to do that. If you'll notice a side shot of the Aircamper with someone in the cockpit, note where the trailing edge of the wing ends up. It can be quite a twist to get in and out without a flop, particularly if you end up tilting your cabanes. Here's an example: ... G_0037.jpg .

    3. I'm pretty sure that everyone will agree that you should wait till the wing is finished (not covered) to varnish it. Don't varnish any surface that will have fabric glued to it. Some builders have gotten creative by connecting a section of plastic aquarium tubing to a pump-type oil can, with the end of the tube attached to a brush such that you can keep the brush loaded with varnish by pumping on the oil can handle after filling it with varnish. It can get very tedious covering all sides and surfaces of all those rib sticks, gussets, and everything else that goes into the wing. I don't know about the inside of the leading edge wrap, but I would imagine that anything concealed inside the wing should get varnished to keep moisture away from it.

    4. You should be able to use a combination of methods to square the wing including stretching a metal tape diagonally both ways across your wing to check that it's the same distance across both diagonals, or perhaps a laser on a guide that you can slide fore and aft while directing the beam out to the wingtip spanwise to see if everything is square that way.

    Just some thoughts.

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 8:07 am
    by Lownslow
    English Johhny,
    I started my Piet in 2003 when I was a fit 56 year old. I have a center section and did not plan on putting a cutout or flop in the center section. Around 7 years later at the age of 63, I had my fuselage done and on its gear legs, as well as the center section and the wing cabanes. I assembled the center section on the fuselage and then mocked up the wings and practiced getting in and out of the fuselage. I had no problem, it was easy. Fast forward to around 2012 I'm now 66. I had the Piet at the airport and had just done the first full assembly. The Piet was not covered but the wings were on and it was on its gear. My AP/IA stopped by to have a look. His asked me how are you going to get in this thing without a cutout or a flop? I said its easy and proceeded to show him. He said "fine, but sit in it for 20 minutes and try to get out. I'll be back." 20 minutes later He was back and I tried to get out. I did it but it wasn't easy. That day I took the wings off and removed the center section. 6 hours of work and I had a flop constructed for the center section. Now in 2017 at the age of 70, I don't know what I would have done without the flop (or a cut-out). I'm sure I would have great difficulty getting in or out. I can still get in the front without much difficulty, but the rear pit would have been a challenge.

    Your question on varnishing....Varnish the wing after assembly. Varnish everything, trying to get into every nook and cranny. Thin the varnish so that you can really slop the varnish on, just make sure you dont have any runs. I did mine outside on sawhorses and had my wife help me rotate the wing panels to check for drips and coverage.

    Glue and screw on the leading edge

    The wing panels are not too long to trammel. I made up my own trammel bar out of a long rectangular wooden board and 2 sharpened nails as trammel points. I glued small squares of thin plywood at the trammel point locations on the spars. I located the trammel points and then put a small punch mark (used a finely sharpened nail) in the plywood at the trammel point locations. I only used the plywood pads as I did not want to put holes, no matter how small, into the top of the spars. With the precisely located punch marks, I was able to trammel the wings unaided, as I could feel when the trammel bar was located precisely at the other end.

    I assembled the wings on two wooden sawhorses, using a long carpenters level and a long straight edge to level.

    Rick Schreiber

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 11:05 am
    by EAB4

    You can save a little headache on the leading edge by marking your rib locations on the inside of the wrap, taping those areas off and
    varnishing the rest of the wrap before you attach it.

    But, as Rick said- wait until your wings are assembled then varnish EVERYTHING.

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 11:12 am
    by taildrags
    Rick; I agree with your assessment of getting in and out of the cockpit at our age. I can slide in and out effortlessly with my flop flipped over, even in winter gear, but it sure would be a pain without it.

    Speaking of our age, I will turn 66 in just a few weeks, so I probably feel some of your pain ;o) In fact, I think we should form an elite insider's club within a club, minimum entry age would be 65 or at the first signs of prostate enlargement (whichever comes first), and it could be called the Pietengeezers. Preflighting for Pietengeezers does not require an E6-B or GPS, no need to calculate wind correction angle or fuel onboard. The time aloft and distance flown are strictly a factor of locations of porta-potties and FBOs. Maybe there's even an app for that ;o)

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 2:14 pm
    by Terry Hand
    Oscar, ... bb030ec6ff

    Beats installing a relief tube.

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 2:35 pm
    by Terry Hand

    Or the relief tube works as well. ... kkey=32007

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 7:01 pm
    by EAB4
    Thought I would add that since you are varnishing everything on the completed wing- your choice of varnish depends on which covering system you will be using.
    If you are using the Polyfiber system you will need to use a 2 part epoxy varnish because the Poly-Tak will dissolve regular varnish.
    If you are using the Stewart system you are fine using a regular spar varnish

    Re: Questions for wing assembly

    Posted: Wed Jun 21, 2017 10:02 pm
    by taildrags
    Terry; of course I was aware of the relief tube solution, but deploying the apparatus in flight can present a challenge while conducting solo flight and attempting to maintaining straight and level. The gel pack seems like it might require less manipulation to deploy but some discretion upon landing, should interested parties approach the aircraft after it's stopped on the ground and the pilot has not taken measures to stow the gear in advance. Thank you for that idea. I'll file it for use in an upcoming edition of the Pietengeezer Newsletter. Coming soon to an, er, "pilot's lounge" near you. It's at the end of the hall on your right ;o)

    Re: Questions for wing assembly

    Posted: Thu Jun 22, 2017 9:01 pm
    by at7000ft
    Yes Stuarts System ecobond works fine over varnish (and it doesn't kill brain cells). I raised my cabanes 2 1/2" and am still very glad I added a flop, I made mine a kind of hybrid, flop and cutout in one.
    [img] ... haring[img]
    Varnished after wing was complete.
    Glue and screw LE.

    Rick H

    Re: Questions for wing assembly

    Posted: Fri Jun 23, 2017 9:35 am
    by Terry Hand

    Just hold the stick between your knees....oh wait, that won't work. :oops: :lol:

    Re: Questions for wing assembly

    Posted: Fri Jul 07, 2017 5:24 am
    by English Johnny
    Thanks for your replies, I've only just got around to setting up the CS on planed wooden bearers to keep it all off the jig table.
    I've squared the CS using a 4ft trammel, Pythagoras calculations on 2 opposite corners, set the spar distances apart equally each end and for level.
    I guess I did everything? I'll post a photo ASAP. I have decided to use a cutout but not sure yet whether to make it triangular of circular, any thoughts?
    English Johnny - In sunny Epsom Downs (home of the Epsom Derby)