Flex wing experimenting

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Alan R

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Had this idea for a flexwing. I had this thought that you could use the booster/engine weight for the balance, not drop it off.
Created this nose piece and 3d printed it.
Attached to 18" spruce spars.
Lightweight ripstop nylon.
Fits in a BT55
The rubber band across the nose spreads the wing.
The wire pieces pulled out, so I used staples for string and rubber connector.
Nylon glued to spars with titebond.
hinge pieces glued to spar with epoxy.
Thread to each side spar to limit degree of spread.

I think the nose and the metal screws are a little heavy, very nose heavy glider, but if I add about 8g clay toward the rear it does seem to actually glide. I found I can order smaller nylon screws. I'd like to try those.

I did lots of reading and know that the cg for a flex wing should actually be about 30% from the front and about same distance below the wing.

I had this idea to actually use the booster as the balance weight, slung below the flex wing. I have some ideas on how I might do that, but I want to move on and do some other builds to free my mind for a bit.

So this post is just to share what I've got so far, I need to take a break from this for a bit.

tinkercad.jpg

IMG_0409.jpgIMG_0403.jpg75D61BA3-97B5-4FD6-8216-D3EFC566FB8C.jpgIMG_0400.jpg
 

Alan R

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Picking this up again.
The 18" glider was too nose heavy. It just dived, couldn't even balance it out with tail clay.

Built a 24" glider. 1/4" basswood spars, 3D printed nose, nylon wing. This one actually seems to work. I didnt trim it, but it does at least glide somewhat without any trimming.

Total weight is about 2.6 oz (75 grams)

IMG_0610.JPG
 

Alan R

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I think that's the sloppiest fin job I've ever done.
 

Alan R

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I need better rubber bands than what I'm using there to pull the wings open. That one seems kind of weak and tears easily.
 

SR71LGT

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Had this idea for a flexwing. I had this thought that you could use the booster/engine weight for the balance, not drop it off.
Created this nose piece and 3d printed it.
Attached to 18" spruce spars.
Lightweight ripstop nylon.
Fits in a BT55
The rubber band across the nose spreads the wing.
The wire pieces pulled out, so I used staples for string and rubber connector.
Nylon glued to spars with titebond.
hinge pieces glued to spar with epoxy.
Thread to each side spar to limit degree of spread.

I think the nose and the metal screws are a little heavy, very nose heavy glider, but if I add about 8g clay toward the rear it does seem to actually glide. I found I can order smaller nylon screws. I'd like to try those.

I did lots of reading and know that the cg for a flex wing should actually be about 30% from the front and about same distance below the wing.

I had this idea to actually use the booster as the balance weight, slung below the flex wing. I have some ideas on how I might do that, but I want to move on and do some other builds to free my mind for a bit.

So this post is just to share what I've got so far, I need to take a break from this for a bit.

View attachment 438356
View attachment 438360View attachment 438357View attachment 438358View attachment 438359
Great concept!!
 

Alan R

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I've been thinking about next steps for a couple of days.
Original idea was to split the upper BT length-wise, and glue each side to the outer spars of the glider. An external coupler would hold the bottom in place for the flight.
Now.. I've decided to sew seams in the nylon because that glue isn't really holding. That means I can't glue the body tube to the outer spars.
I don't trust an ejection charge to blow the entire glider out of the tube, especially if it's pretty tight.
New options: keep the split tube idea, but use seam tape on one side, attach it at the seam to either the upper or lower side of the center spar
Option 2, just attach it all together somehow and let it dangle

Also, I think I'm going to go with music wire spring to pop it open instead of rubber. I tried different rubber, but it never seems like it's got a strong enough pull to hold it tight.
 

Alan R

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Thanks @Ez2cDave , there's a couple of new ones in that list that I didnt find in my previoius research.
the 18" version was too heavy to fly. nose dived
the 24" version works nice right out of the gate. It mostly glides without any trimming so far. That made me happy. It just needs a bit of tail weight, but carring the spent motor should make it work like i want
 

Ez2cDave

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Alan,

George Gassaway has a huge amount of experience with Flex-Wings . . . I hope he will comment here !

Dave F.
 

Alan R

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George Gassaway has a huge amount of experience with Flex-Wings . . . I hope he will comment here !
Haven't had a problem with the wing. Flex wings are easy. Ever since I enlarged it, the nose weight has not been a problem. Right now i'm working on the engineering problems of popping it open and trying to figure out how I attach the rest of the rocket to the wing.
Were you aware that piano wire has suddenly become impossible to find? Hobby shop guy said they can't get it any more.
 

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Alan R

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Exactly the kind of thing I had in mind. a couple of threads to the booster section hanging under the center spar.
 

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I've been thinking about next steps for a couple of days.
Original idea was to split the upper BT length-wise, and glue each side to the outer spars of the glider. An external coupler would hold the bottom in place for the flight.
Now.. I've decided to sew seams in the nylon because that glue isn't really holding. That means I can't glue the body tube to the outer spars.
I don't trust an ejection charge to blow the entire glider out of the tube, especially if it's pretty tight.
New options: keep the split tube idea, but use seam tape on one side, attach it at the seam to either the upper or lower side of the center spar
Option 2, just attach it all together somehow and let it dangle

Also, I think I'm going to go with music wire spring to pop it open instead of rubber. I tried different rubber, but it never seems like it's got a strong enough pull to hold it tight.
check out the extensible flexwing article here for some ideas:


I assume you are going to eject the fin can and just fly the flexwing by itself.

also see the jan/feb 72 issue on page 2. http://www.ninfinger.org/rockets/ModelRocketry/Model_Rocketry_v04n04_(01-02)-72.pdf
 

Ez2cDave

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I assume you are going to eject the fin can and just fly the flexwing by itself.
Terry,

I believe that he intends to recover the entire rocket, using a Rogallo Wing instead of a parachute.

Dave F.
 

Alan R

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Glue wasn't holding on that nylon. Dropped it off at a local seamstress and got it back yesterday.
She did an awesome job, bonus points for orange thread.

IMG_0668.JPG
 

Alan R

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I believe that he intends to recover the entire rocket, using a Rogallo Wing instead of a parachute.
That's the grand idea in my mind.
I still have lots of engineering problems to overcome
 

Alan R

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I just had an inspiration.
Original idea would be that the body tube would be split in half and attached to the outer spars of the flex wing. I've been trying to figure out how i would do that.
Since the flex wing is now sewed up tight, I don't have any attachment points to the spars.
today I realized... I can just drop the tube. tumble recovery. maybe put a streamer in there so I can find it. Not really what I originally wanted, but much more feasible from engineering standpoint. It would be split lengthwise on both sides. Tape down one side like a hinge.
Outer couplers would hold it together at the nc and booster. ejection and flex spring just causes it to pop out of the way
 

Ez2cDave

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Original idea would be that the body tube would be split in half and attached to the outer spars of the flex wing. I've been trying to figure out how i would do that.
Here's a concept from "back in the day", from CMR ( Competition Model Rockets ).

Dave F.


CMR_Catalog_1972_pp8-9.jpg
 

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caveduck

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Music wire (spring steel wire) is still readily available in all conceivable sizes on McMaster: https://www.mcmaster.com/spring-wire/lubricated-1080-spring-steel-wire/

If your flexie dives, one of the pro secrets is to stretch the material tighter across the front part of the frame up near the hinges.

I learned to fly *real* hang gliders on a Rogallo type wing in the early 1980s, though full-frame rigid wings took over rapidly during the couple of years I was flying a lot.
 

shockie

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Music wire (spring steel wire) is still readily available in all conceivable sizes on McMaster: https://www.mcmaster.com/spring-wire/lubricated-1080-spring-steel-wire/

If your flexie dives, one of the pro secrets is to stretch the material tighter across the front part of the frame up near the hinges.

I learned to fly *real* hang gliders on a Rogallo type wing in the early 1980s, though full-frame rigid wings took over rapidly during the couple of years I was flying a lot.
Dave: are you the Dave Cook from September 1976 Model Rocketeer: Flex Your Wings! Applying the Rogallo Wing to Model Rocketry
 

Ez2cDave

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Dave: are you the Dave Cook from September 1976 Model Rocketeer: Flex Your Wings! Applying the Rogallo Wing to Model Rocketry
Terry,

Yes, he is THE Dave Cook . . .

Dave F.
 

Lee

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Somewhere I read of this concept: Hold those wings snug to the BT while launching with a thin, combustible thread. The thread runs through the MMT close to the ejection end of the engine. At apogee, the ejection charge burns the thread, releasing the wings to sprout open.
 
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