Fauvel AV-36 and 361 plans project

Discussion in 'Member Project Logs' started by Hot Wings, Jul 7, 2019.

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  1. Jul 7, 2019 #1

    Hot Wings

    Hot Wings

    Hot Wings

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    This is not a traditional aircraft build, at least not yet. I have taken on the responsibility for the AV-36 after purchasing Falconair's rights to the design. After receiving the documentation It became apparent the the plans needed some significant updating. The 'master' plans showed their age due to the wear and tear of being used to copy them for each set of plans sold. They were never converted to digital format. Some of the masters are even negatives - white lines on black background. I've had the plans scanned locally so that i have a digital set to work with while redrawing the plans into CAD specifically Solidworks.

    This will/should result is a set of plans that are accurate and much easier to read. In addition 3D pdf files can be generated which should aid int visualizing what is being built.

    Obviously the CAD files won't be posted but I hope to post various screen shots and links to 3d PDF files as I am able to find time to work on this project. I'd post the 3D PDF files here, but they are generally pretty big and I see no reason to fill up HBA's server with large files that are likely to be of interest to only a few of our members.

    A sample of the original plans:
    HBA fuselage.jpg

    And the CAD rendering of the part:

    Frame 2.jpg

    Link to comment thread:
    https://www.homebuiltairplanes.com/forums/threads/fauvel-av-36-and-361-project.31891/
     
    Last edited: Jul 7, 2019
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  2. Jul 8, 2019 #2

    addicted2climbing

    addicted2climbing

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    Hello Hotwings
    Cool project. I am doing the same with the Raceair Skylite. I started a build thread seperateky from a discussion thread to chronicle the progression from plans to subassemblies in Solidworks. Best of luck on this and will be following for sure.

    Marc
     
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  3. Jul 18, 2019 #3

    Hot Wings

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    CAD computer smoked a power plug on one of the hard drives. Fortunately the hard drive survived. This is the second time a cheap SATA/Molex adapter has internally shorted. I'm now out of adapters....but I do keep a spare power supply at all times.

    Just a couple of screen shots to add. Finally got the wing loft correct so I can now begin to carve out the individual parts. The original airfoil nose profile is made up of 2 radius. This works fine for a hand build wooden wing but CAD revealed a nasty little bump in the lower surface that really messed up things when put into JavaFoil. Smoothing things up with a hand generated spline improved things in JavaFoil extremely well. Variation from the original nose arcs is less than 1/3mm.

    Just for fun I tried to see how a wing fold at the end of the airbrakes would work. This could make the AV-361 as compact on a trailer as the Pelican flying wing. It would also add complexity and will have to wait until I have the plans ready for printing with no modifications.
    Wing basic loft - Fauvel smoothed nose.JPG Wing fold.JPG
     
    Last edited: Jul 18, 2019
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  4. Jul 19, 2019 #4

    Hot Wings

    Hot Wings

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    Today's work partial spar.JPG I'm thinking a composite AV-48 would be SO much easier and quicker to build.
     
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  5. Jul 19, 2019 #5

    addicted2climbing

    addicted2climbing

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    Wow Looks great. Been more than a week and the thread mentions both the AV36 and Pelican and Victor Bravo has not chimed in yet... :)

    Have you read the little yellow book by Marske yet? He mentions sarting with the airfoils from the AV36 in the beginning and diverging toward his own for various reasons. He is very approachable and you may reach out to him as to why? Also he was working on a followup to the yellow book, so may have some pertinent info you could use.
     
  6. Jul 19, 2019 #6

    Hot Wings

    Hot Wings

    Hot Wings

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    The Yellow Book is unknown to me. I'll have to do some searching. Thanks for the lead.

    I'm pretty sure that there are better airfoils than the Fauvel, after all 40% of the underside is flat! But when I put it into JavaFoil I was VERY surprised by the numbers. My other objective with this project is to simply reproduce the original plans as faithfully as possible rather than "improve the design" them at this stage. Having plans to a proven airframe is one of the reasons I bought the rights from Falconair.

    Later when I have the time to build my own I'll build it with some of my ideas to improve the build time and reduce the cost. It will be an AV-45ish fuselage and an AV-361 wing. I intend to follow Fauvel's lead and keep things modular so an existing AV-36 wing can easily be grafted to an AV-361 or AV-45 fuselage.

    One interesting bit of trivia that has emerged from the CAD work is that the AV is not a plank. Due to the fact that Fauvel used 30% chord for the datum it has .72 degrees of sweep about the 25% chord.
     
  7. Jul 19, 2019 #7

    addicted2climbing

    addicted2climbing

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    Hotwings, I just realized I commented on your build log. You might want to make it private to avoid that. Sorry for the error...
     
  8. Jul 19, 2019 #8

    Hot Wings

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    It was really private for a while. Even I couldn't post. It started out as private but admin has been working on the software. I'll have to see what is involved in returning it to private.

    Who knows maybe it will work out better this way?
     
  9. Aug 25, 2019 #9

    Hot Wings

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    Had a little change in plans since the last update with regard to the fuselage. Trying to simply duplicate the 2D plans wasn't taking full advantage of modern CAD and would have left some of the original ambiguities of the original plans. They were causing me enough trouble simply trying to make sure the parts actually matched in an assembly that I can only imagine some of the frustration a builder would have with real world parts.

    Combining this with the fact that modern pilots are larger than those of the 1950's and it was noted that the original AV-36 fuselage was already a bit narrow I determined that a reloft of the original was the best option even if it meant some backtracking. Rather than use the AV-36 as the base I used the AV-361 fuselage and widened it an additional 1 3/4 inch at the shoulders. This change is all cosmetic and will not require any change of primary structure or systems.

    Re-lofting allowed me to change the profile somewhat to imitate the plane on the right of this picture posted by HBA member Arfang.
    I think it will improve the pilot visibility and make construction simpler. It will also allow the builder to choose the style of canopy they desire - be it blown or flat wrapped.

    The complete re-loft also means that things like fuselage bulkhead ply sheeting can be cut to fit both the front and back of the bulkheads. This would have been nearly impossible from the 2D prints.

    I also like the look of the lower tapered nose better. This is what the basic loft now looks like:
    Fuselage loft - taper nose.JPG
    The aft canopy is just a filler at this point.
     
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  10. Aug 28, 2019 #10

    Hot Wings

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    "Finished" the first bulkhead from the wider re-lofted fuselage. Took far too long because I had to learn a few new tricks to deal with offset splines in Solidworks.
    34 individual parts and 9300 grams (minus glue and nails)

    Plan is to have the skins CNC cut and provide pre-laminated side curves at some point in the future.
    361 bulkhead #3 new loft.JPG
     
  11. Aug 28, 2019 #11

    Hot Wings

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    No, it's not a Raptor. Just forgot to not include the mass of the hidden "plug" used as the foundation.

    850 grams minus glue, nails and varnish. Material of plug changed to air so this shouldn't happen again.........:oops:
     
  12. Aug 30, 2019 #12

    Hot Wings

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    Here is a PDF of one of Falconairs info packs. It's obviously not current but I thought it would be of historical interest and it does have some still relevant info.
    Low resolution version here. If you want a higher resolution and some other AV-36 historical info join my GroupsIO group.
    Cutaway_000002.jpg
     

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  13. Sep 1, 2019 #13

    Hot Wings

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    Getting comfortable with dealing with offset splines in Solidworks. Front bulkhead 'finished' today.

    Fuselage loft - taper nose - Bulkhead child-Core 0.JPG
    There is significant taper from the front face to the rear - thus the odd looking gap on the front skin around the perimeter.

    Another 351 grams - minus nails, glue and varnish.
     
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  14. Sep 2, 2019 #14

    Hot Wings

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    Found the first real mistake in the plans today while working on the tail fuselage bulkhead. Can't tell if if was the result of using a different datum for part of the drawing or if it was an error trying to calculate a 7.5 degree slope on a slide rule. So far, once the poor condition plans are properly read, they have proven to be pretty accurate. Most deviations from the drawing to digital CAD are less than 1mm.

    Unfortunately the error surrounds where the aft wing attach fittings are so I won't know which part of the drawing is correct until I get that section of the wing drawn.
    Fuselage loft - taper nose - Bulkhead child-Core 3.JPG

    The bottom half of the print is as close as one can get with a scaled JPG. This is the last fuselage bulkhead so I'm moving on to the wing center section and will come back to this once I have the matching parts.
     
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  15. Sep 14, 2019 #15

    Hot Wings

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    Started work on the Schempp Hirth style spoilers/brake system. I've discovered that there are only sketches of this system left. There are very few dimensions available - even in the original French set. This means I get to do some engineering to spec and size a lot of the parts. It looks like a toss up as far as build time and cost between the AV-36 air-brakes and the AV-361 spoilers. History says that the SH style are much better so it's probably worth the time?
    The AV-45 drawings are of only marginal help.
    This would have been a lot easier if Fauvel's wife hadn't burned everything.........:(

    Spoiler control assembly.JPG
    Rough outline with a bunch of place holder parts.
     
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  16. Sep 24, 2019 #16

    Hot Wings

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    Work has progressed on the modifications needed to use a center main wheel near the CG with the intent to get rid of the porpoising on landing due to the nose gear contacting first. The good news is that there is plenty of room for all of the parts and the parts count on the revised control system is about the same as the original. The tubular welded aileron "V" is stiffer than the original massive aluminum plate and lighter as well. As usual the Solidworks napkin grade sketch has a lot of place holder parts - like the pulley bracket used for the elevator bell-crank pivot. :rolleyes:

    This all means a completely revised #2 bulkhead but that will give me the opportunity to improve the shoulder harness mounts and add seat belt mounts, which the original plans didn't include :eek:. Center wheel control assembly.JPG

    The plans when finished will have the drawings for the original control system used with the skid, in addition to the revised center wheel system.

    Next is the chore of detail design of the parts.........
    After I get the basics of the vertical stab/rudder drawn up. Switching projects like this tends to let my subconscious mind find flaws and/or improvements to the last phase.

    Edit:
    Just realized that the AV-45 style airbrake linkage with the center pivot, while simpler, results in asymmetrical deployment. So it is back to the AV-361 system. Moving the center mount enough to give symmetrical movement puts the pushrods outside the wing. :(
     
    Last edited: Sep 24, 2019
  17. Sep 24, 2019 #17

    Hot Wings

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    With simplified AV361 spoiler linkage
    And a couple of 9000W electric motors just for fun :cool: AV361 linkage.JPG
     
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  18. Sep 29, 2019 #18

    Hot Wings

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    Working on the rudder. Re-lofted the ribs with something closer to a NACA symmetrical airfoil to get rid of the old French javelin pointed thing.o_O Might be worth a quarter point in L/D?
    Discovered in the process that the AV-361 and AV-45 are identical above the chord line so this will make the work a bit easier to adapt the AV-45 rudder to a self-launch AV-36/361.
    AV45 rudder loft raw.JPG AV45 rudder loft.JPG
     
  19. Oct 1, 2019 #19

    Hot Wings

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    Still working on the rudder assembly. The loft is now locked down and I'm starting to carve out the individual parts. Eventually all of the little sub assemblies will look like the #5 rib below - with dimensioned drawings to match.
    The yellow are my trade-marked Yellow Air bodies for child parts. Keeps me from ending up with strangely heavy parts if I forget I have 2 bodies occupying the same space. It's not possible in the real world but SW doesn't mind one bit. :oops:
    example.JPG Yellow air.JPG
    Took some artistic liberties with the rudder curve. A simple arc is easier to make than the spline curve, both in SW and the real world.
     

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  20. Oct 2, 2019 #20

    Hot Wings

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    Still working on the individual rudder parts. It has become apparent it is now time to set up the part number system. I have a system developed from prior similar projects that should work well here. Basically its is in the format:
    ABD-##R/L-revision#-asm

    ABD = quick hint about location. FS = Fuselage; VS = Vertical stab; LG = landing gear with the third letter indicating sub part.
    asm = indicates it is a sub assembly rather than a single part. ASM indicates a major assembly.

    An Excel file will go with the plans for quick and easy lookup. Example attached.
     

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