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PRANDTL-D Foam Board Wing by FoamyDM

What plane should I add the Prandtl-D Wing to?

  • Mini-Arrow

    Votes: 11 44.0%
  • FT-Explorer

    Votes: 7 28.0%
  • FoamyDM-HS Carrier

    Votes: 4 16.0%
  • FT-Simple Cub

    Votes: 3 12.0%
  • FT-Tiny Trainer

    Votes: 6 24.0%
  • FT-Bloody Baron (somehow)

    Votes: 4 16.0%
  • Airliner

    Votes: 6 24.0%

  • Total voters
    25

FoamyDM

Building Fool-Flying Noob
#22
@kilroy07, I haven't even fathomed it yet.

So I'm calling it a night before I do something stupid!😒

Don't get me wrong, but I am CRAZY Excited about this build and it's progress.

I found my glue stick nest... And got to working.
IMG_20190508_000029022.jpg
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Note the curve and the bump in the leading edge.

Then I got to work on the other half:
IMG_20190507_233212114.jpg
IMG_20190507_233318879.jpg

The I put them together, and viola!
IMG_20190508_001527151.jpg
IMG_20190508_001521517.jpg
IMG_20190508_001609569.jpg IMG_20190508_002231852.jpg IMG_20190508_003046233.jpg

This is where I need to quit...
I started measure in balance spots and weight.
IMG_20190508_002259882.jpg

Tradition is I go fly it in the front yard... In the dark...🤠🤔😩😒
It will wait. It is one piece of DTFB with almost no waste. So... ~100g estimate?

Here my video test of the rigidity. Stiffer might be desired. But we shall see.

Back to the beginning.... I wait. And done't be a fool.😜
 
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FoamyDM

Building Fool-Flying Noob
#27
I had very little daylight minutes to test this yesterday. Balanced at the plan CG marks with 21g (4 quarters) at the pencil mark ~1" from the nosetip is much to tail heavy. It looped nearly immediately.
so I added more weight. about 11 grams (2 Quarters) and another go.. push- curve up-stall. I'm close. add more 5g, and push it up. to the nose tip.
Now it flies! something isn't symmetrical. it consistently turns left. (Of three balanced launches).
my launch was more of a dart toss at the rear apex (where I would put a motor mount.)

Based on those three tosses I learned little. BUT, of those I learned it Yaws left as well - PROVERSE YAW B!TCHES!

More tests coming. And video.
 

Vimana89

Well-known member
#29
TT would be a good candidate for sure, but I think the explorer would look just perfect with this wing. The arrow is a natural fit, and I'm also the only one who voted for airliner so far. An airliner style fuselage would look really clean with this wing.
 

FoamyDM

Building Fool-Flying Noob
#30
TT would be a good candidate for sure, but I think the explorer would look just perfect with this wing. The arrow is a natural fit, and I'm also the only one who voted for airliner so far. An airliner style fuselage would look really clean with this wing.
pSST. - Just between us... I plane to do them all ;) (I suppose I have enough start filling in the build log section)
 

FoamyDM

Building Fool-Flying Noob
#32
An airliner style fuselage would look really clean with this wing.
I looked at my fleet and noticed I have a distinct gap with jet-liner craft. I have looked at a number and plan to build a few. I suspect the new 50mm edfs will find a home with these builds.

As a plus, my girlfriend used to work for Piedmont Airlines, and this wing on an airliner body might help pull her deeper in. 🤠
 

Vimana89

Well-known member
#33
I looked at my fleet and noticed I have a distinct gap with jet-liner craft. I have looked at a number and plan to build a few. I suspect the new 50mm edfs will find a home with these builds.

As a plus, my girlfriend used to work for Piedmont Airlines, and this wing on an airliner body might help pull her deeper in. 🤠
Very nice.I see a distinct lack of any type of airliners, jet or prop driven, in the FT line up of designs, and not many foam board scratch builders tackling them. I've had some interest in the Dash 8 turbo prop airliner for a while, and it won the "what should my next scratch build be" poll, so that sealed the deal. I'll be ordering parts soon and learning how to do twin engine, which is a whole new ballgame to me.
 

FoamyDM

Building Fool-Flying Noob
#34
I did my glide test now, I put 40 g of coinage in the very nose of the plane and had it glide very well at this point it's probably just a variation of a couple grams to make it optimal I noticed that when it would Bank it would also proverse yaw even if it's just a little this point which is spectacular!

Take a look for yourself:

On a decent dart toss. It traveled clear across the lot. ~100'/5' drop = 20:1.
 

mayan

Well-known member
#35
You could see it a couple of times, I’d personally love for another video in daylight. Did you experience and wiggle towards the tips of the wings?
 

kilroy07

Well-known member
#36
Yea, we need lights on the next one! 😃 (yea I know you were too excited to wait....)

20:1 is pretty dang impressive for dtfb!
I still haven’t found the time to read the nasa paper on this, are you planning to add control surfaces?
Or just drive it with a tail? (Or would a tail just remove all the positive traits....) 🤔

On your next wing please take more pics of the process of getting the twist in.... I’m still really curious how you managed that. I probably won’t get to one of these till after FF (got a few projects in the ready cue) but I am really intreagued by your success trying to build such a wing out of dtfb! 👍👍
 

FoamyDM

Building Fool-Flying Noob
#37
You could see it a couple of times, I’d personally love for another video in daylight. Did you experience and wiggle towards the tips of the wings?
As and ye shall receive! (i before e except after...got it)
I think I could use *just* a little more weight
Last night it hit the garage and bent. you can see crease at the very end.
 
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#38
TT would be a good candidate for sure, but I think the explorer would look just perfect with this wing. The arrow is a natural fit, and I'm also the only one who voted for airliner so far. An airliner style fuselage would look really clean with this wing.
pSST. - Just between us... I plane to do them all ;) (I suppose I have enough start filling in the build log section)
Anything with a tail would negate the main benefit of this design... Proverse yaw means you dont need a rudder to coordinate turns so you can save yourself the weight of those components.
I've venture to say that flying wings and rudder-less canard configurations would see the most benefit from this wing configuration.

My idea for getting the twist in with FB was to 3D print a bunch of negative formers (they go in the outside of the wing) about every inch or two. One set for the bottom of the wing and another for the top.
Massage the foam for the lower wing skin into the general shape and then weigh it down onto the bottom formers.
Glue my spar in while making sure the shape still matches the formers and then fold the top skin foam and use the top formers to sandwich everything into shape while the glue dries.
 
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FoamyDM

Building Fool-Flying Noob
#39
Yea, we need lights on the next one! 😃 (yea I know you were too excited to wait....)

20:1 is pretty dang impressive for dtfb!
I still haven’t found the time to read the nasa paper on this, are you planning to add control surfaces?
Or just drive it with a tail? (Or would a tail just remove all the positive traits....) 🤔

On your next wing please take more pics of the process of getting the twist in.... I’m still really curious how you managed that. I probably won’t get to one of these till after FF (got a few projects in the ready cue) but I am really intreagued by your success trying to build such a wing out of dtfb! 👍👍
I Will. (I've always noticed. how twist-able the foam can be, and figured if it gets glued that way, it will stay twisted and strong-ish.)
The Key is the 1/2" wood block. and hot glue being hot, slippery at first and sticky.

Quick Joke: What is Brown and Sticky? :poop:
Spoiler!

For the twist to occur, the front edge height as it tapers goes from 1" at the base, to 1/2" at the first segment then the second segment stays near that 1/2" for the inner 1/3 of the outer Segment. the end is Flat. The build Process is get the inner segment glued up, line up the rear edge the front edge supported as described. weight it down, pressing the rear edge closed which is flat against the table.and wait for it to fully cool. (heat sinks, like the ruler help). then do the other section. which is 50% two sheets direct pressed, creating a shear surface rigidity. but as it is rubbery glue there is flex. (I suppose gorilla glue might be stiffer.
 
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FoamyDM

Building Fool-Flying Noob
#40
Anything with a tail would negate the main benefit of this design... Proverse yaw means you dont need a rudder to coordinate turns so you can save yourself the weight of those components.
I've venture to say that flying wings and rudder-less canard configurations would see the most benefit from this wing configuration.
Every plane I add this wing to will NOT have a tail.

My idea for getting the twist in with FB was to 3D print a bunch of negative formers (they go in the outside of the wing) about every inch or two. One set for the bottom of the wing and another for the top.
Massage the foam for the lower wing skin into the general shape and then weigh it down onto the bottom formers.
Glue my spar in while making sure the shape still matches the formers and then fold the top skin foam and use the top formers to sandwich everything into shape while the glue dries.
My brain started there. I considered doing that sandwich method... and realize how much of a pain it will be, to cut out, set up, and ensure everything was perfect. Laziness drove me to consider a simpler method. Sometimes that's the best method. Give it a try and tell us about your success!