Aft/Rear Wing Glider Recovery

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RocketRev

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I've been thinking of starting a new rocket glider project which will require a deployable rear/aft wing. Anybody know where the CP/CG needs to be for a deployed rear wing glider? I am looking for both "rule of thumb" information as well as actual math formulas. Are there any computer programs out there for rocket gliders and or aft wing rocket gliders?

Brad, the "Rocket Rev.," Wilson
 

kjohnson

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Are you talking about something like the Reinhold Tiling rocket glider, a canard glider like the Edmond's CiCi, or something else?

kj

Tiling-mit-rakete.jpg
 
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RocketRev

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Oddly enough, I am thinking about a combination of the two. I was unaware of either rocket design that you mentioned, but two quick google searches and I know what you're talking about.

I am thinking about building a rocket with deployable wings like Tiling's design, only I want the wings facing forward during powered ascent. I hope to deploy them at apogee. But at wing deployment, I think that I will also need canards in the front like the Edmonds CICI design. Though I'd prefer that the canards also wait till apogee for deployment. But as I said, this is a new idea and I'm looking for help as there seems little information on rear wing gliders.

Do you know where I could look for info on rear wing gliders?

Any help would be appreciated.

Brad
 

georgegassaway

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I am thinking about building a rocket with deployable wings like Tiling's design, only I want the wings facing forward during powered ascent. I hope to deploy them at apogee. But at wing deployment, I think that I will also need canards in the front like the Edmonds CICI design.
Uh....hmm. If the wings are swept forward for boost, the launch Center of Pressure will be very far ahead of where it will be for glide. If you add so much noseweight that it is stable on boost, then it will be fatally nose-heavy for glide. If you do not add plenty of noseweight in order to keep the glide CG correct, then it will be fatally unstable on boost.

This is the opposite of a normal swing-wing rocket boosted glider, where having the wing back for boost makes the model's CP move a lot behind the CG and so it is extremely stable, then when the wings deploy, the CP moves a lot closer to the CG for proper glide trim (if the CG was set up right to begin with)



Another issue with having the wings swept forward, is that the oncoming airflow is going to pry on the wings and bend the "tip" of the wing (up front on boost) out of parallel with the body/fuselage. An effect of Aeroelastic Divergence - https://en.wikipedia.org/wiki/Aeroelasticity#Divergence

At the least, that would act like a canard "up elevator" (or down elevator) to pitch it into a loop or half-loop. Or, the wing will bend too far and snap (or flutter/shred). So, you'd need to add some horizontal guides (like dowels) sticking out sideways from the fuselage to trap the wings so the forward tips could not bend like that.

Back to swing-wings, here is a link to a thread I started on TRF long ago, including a lot of photos:

https://www.rocketryforum.com/showt...Wing-Gliders-Wing-hinges-(and-BIG-models-too)

And this is an article I wrote with tips for B sized Rocket Gliders, which includes some info on SwingWing Gliders:

https://georgesrockets.com/GRP/AOL/GCGassaway/contest/rocket_glide.htm

Which includes this:



Here's a photo of a 6.5 foot span swing-wing that I added rudder-only R/C to:




And this video clip, from a old 8mm movie shot in 1976, showing another 6.5 foot swing wing boosting, and deploying. And also later, it's pop-stab DT (rear 2/3 of horizontal tail popped up 90 degrees) activated to make it descend belly-flop style rather than risk gliding away.

[video=youtube;m0YjlaZvLRU]https://www.youtube.com/watch?v=m0YjlaZvLRU[/video]
 
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kjohnson

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George covered the aero issues pretty well. In a sense of thinking about solutions, a way to prevent the negative impacts of the forward stored wings is to try and find a way to put them internally to the body of the rocket. That has it's own set of problems, and limits the size of the wings you can use, unless you make the wings flexible or made of sliding overlapping plates (another technical challenge). I have seen old plans for a deployable canard glider, and they were really complicated and looked like they needed a lot of luck to deploy.

kj
 

RocketRev

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Hello George and KJ too,

Thanks for lots of things to think about.

I might as well let the cat out of the bag as somebody needs to build this thing even I never succeed at it. I am thinking about building a partly scale model of the Rogue One, space ship. Not the U-wing fighter, but the U wing transport. There are lots of ways to use the fuselage/airframe itself to shield the wings during boost. Everything you've brought up is great information.

I am also thinking about using the four rear engines behind the wing as tube fins to help in flight stability.

My question is, once the wings are deployed, where does the CP/CG need to be located on an aft/wing glider for a stable glide recovery? Its the theory that I'm looking for at this point.

Brad
 

burkefj

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I'd start simpler and do a gliding version with swept wings, that's a pretty straight forward flying wing style, get it to boost and fly well then think about swing wings, I dont think you need canards, The elevons should work, you'll need a wider chord most likely.

Frank
 

kjohnson

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Looks like with wings open it's just a typical flying wing design with a pod. Look on line for stability of flying wings and you'll find a lot of useful information.

In the stowed configuration those wings stick way out in front and the tips are going to act like forward fins, really making your CP/CG relationship messy. Not even considering the point that George brought up about them flexing and acting like canards. I don't even know how you'd make them stiff enough to to bend. Maybe consider having some sort of extension tube out the front that has some nose weight and also holds the tips until deployment? Not the prettiest solution, but one that has been done before (think about the old Estes Enterprise kit).

kj

NEpR3198cF04rt_1_5.jpg


Star-Wars-Rogue-One-U-Wing-1_4.jpg
 
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