Help with model rocket

  • #1

Main Question or Discussion Point

I am trying to build a model rocket for a contest. It goes up as a rocket but comes down as a glider. Vertical takeoff. Does not jettison any parts. Should glide down in large slow graceful circles. Judged based on total hang time. I have been able to avoid a outright nose dive by putting the cp really close behind the cg, but haven't achieved a glide. Any suggestions?
 

Answers and Replies

  • #2
DaveC426913
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Wings? ;)
 
  • #3
Yes they are an option. I used a long flat balsa wood wing but the wood snapped a short distance from the body during liftoff
 
  • #4
DaveC426913
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If you're looking to have it glide, wings are not an "option"; they are mandatory.

(Well, I suppose alternately you could have a parachute.)
 
  • #5
parachute not allowed
 
  • #6
DaveC426913
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How do you expect to achieve any glide if you are still considering wings as optional?
 
  • #7
phinds
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To expand on what Dave said (which is certainly true) can you see a way to arrange wings so that they don't snap off at liftoff but DO have an effect on the way down? I see one immediate solution that I believe could be made to work
 
  • #8
You can launch whit rocket something like this (rocket propelled UAV) dependent on rockets useful payload mass:
AIR_UAV_Skylark-I-LE_from_Below_lg.jpg


Alternatively you can use servos ,larger wings and remote controller to control flight
9b0413cc14dff51eacf87811b35456a9.jpg
 
  • #9
phinds
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You can launch whit rocket something like this (rocket propelled UAV) dependent on rockets useful payload mass:
Violates the condition of vertical takeoff.
Alternatively you can use servos ,larger wings and remote controller to control flight
Violates the condition of coming back like a glider.

I realize you are being creative here, but you are not answering the question as asked. I have taken the requirements as being part of the problem to be solved.
 
  • #10
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Can you design it so that the wings will fold up and deploy when the rocket is falling? I know that some rockets deploy a parachute with a small detonation, so maybe you can use that to forcibly deploy some wings.
 
  • #11
phinds
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Can you design it so that the wings will fold up and deploy when the rocket is falling? I know that some rockets deploy a parachute with a small detonation, so maybe you can use that to forcibly deploy some wings.
This is what I was trying to lead the OP to (the deployment, although not quite your method), rather than spoon-feeding him the solution, since spoon-feeding is frowned on here on PF.
 
  • #12
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This is what I was trying to lead the OP to (the deployment, although not quite your method), rather than spoon-feeding him the solution, since spoon-feeding is frowned on here on PF.
Sorry @phinds! I didn't catch what you were trying to do. I guess subtlety isn't my strong suit. I figured the real challenge would be to design the vehicle for a long hang time, not in coming up with mechanisms for deployment. To me, ideas are a dime a dozen, but implementation is going to be where Eliott will really have to stretch and think.
 
  • #13
phinds
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Sorry @phinds! I didn't catch what you were trying to do. I guess subtlety isn't my strong suit. I figured the real challenge would be to design the vehicle for a long hang time, not in coming up with mechanisms for deployment. To me, ideas are a dime a dozen, but implementation is going to be where Eliott will really have to stretch and think.
Yeah, I sometimes get carried away too by my interest in a problem and coming up with a solution and forget that we're here to help folks figure out how to do that for themselves. I often have to bite my tongue, so to speak, so I know where you're coming from. And yes, you're right that implementation will be non-trivial but you DO have to figure out first just what it is that you want to implement and that's what I wanted to lead him to.
 
  • #14
Phinds- next I will try having them make shorter, and I guess tapered.
Dave- I meant they are allowed
Time- it's not allowed to change shape significantly
 
  • #15
phinds
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Phinds- next I will try having them make shorter, and I guess tapered.
Dave- I meant they are allowed
Time- it's not allowed to change shape significantly
Hm ... not sure that will do the job. I had in mind a variation on the reaper's suggestion ... wings that are unobtrusive at liftoff but spread out at apogee
 
  • #16
Aileron allowed ?
 
  • #17
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not allowed to change shape significantly
What is this? Something from a BOMARC missile design competition from the 50s? Hit the library for old "Jane's" and start looking at Snark, Matador, Bomarc, designs.
 
  • #18
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Wings which fold out sounds like a good idea. Could also use swept wings as the stabilizers during launch configuration. Once at max altitude the swept wings could fold out (like on the F-14) into a more or less glider configuration. You will need a second set of stabilizers behind the main wing though for flight stability.
 
  • #19
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Well, since I let the cat out of the bag, here's a US military adaptation of this kind of rocket/plane:

-- watch 46:08-46:50
-- for a more promotional video,

You could do something along these lines.
 

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