PRANDTL-D Foam Board Wing by FoamyDM
- Thread starter FoamyDM
- Start date
@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.
Note the curve and the bump in the leading edge.
Then I got to work on the other half:
The I put them together, and viola!
This is where I need to quit...
I started measure in balance spots and weight.
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.😜
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.
Note the curve and the bump in the leading edge.
Then I got to work on the other half:
The I put them together, and viola!
This is where I need to quit...
I started measure in balance spots and weight.
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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bracesport
Legendary member
@bracesport I think you're right. The spar I used was a THIN piece of FB. relying on the Glue to do most of the work...
@kilroy07 Thanks! I have one of those ready.
@kilroy07 Thanks! I have one of those ready.
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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 YAWB!TCHES!
More tests coming. And video.
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
More tests coming. And video.
mayan
Legendary member
OOOOOO, sounds good
.
pSST. - Just between us... I plane to do them all
(I suppose I have enough start filling in the build log section)
Vimana89
Legendary member
Awesome. Had a feeling you'd want to experiment with multiple options👍. I'll be following this one.pSST. - Just between us... I plane to do them all
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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
Legendary member
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.
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.
Take a look for yourself:
On a decent dart toss. It traveled clear across the lot. ~100'/5' drop = 20:1.
kilroy07
Legendary member
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! 👍👍
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! 👍👍
As and ye shall receive! (i before e except after...got it)
Last night it hit the garage and bent. you can see crease at the very end.
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GMalatrasi
Active member
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.pSST. - Just between us... I plane to do them all
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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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?
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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Every plane I add this wing to will NOT have a tail.
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!
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