| WSF rocket, C size [message #43429] Sat, 04 February 2012 02:03 UTC |
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hey peeps.
Ok so I designed a rocket for 3d print. Having not a lot of experience with WSF I was wondering if anyone could shed some light onto the integrity of my model.
The fins are 1mm at the thinnest point and 1.5 at the top tapering down. the main body of the rocket in just a 1mm thick shell to house the solid fuel engine.
Can anyone tell me if the strength of the WSF will be strong enough handle the g-force?( i normally use balsa so it seems strong enough to me) and also will the rocket warp or break during delivery? (if so i might have to make the fins separate and glue together myself)
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| Re: WSF rocket, C size [message #43443 is a reply to message #43431 ] Sat, 04 February 2012 12:07 UTC |
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I would think that the rocket would survive the G forces, WSF is strong and bends a long way before it'll fail.
Have you thought about adjusting the pitch of the fins so the rocket will spin in the air? Also what about adding a counter weight for the guide on the side of the rocket? I'd have thought that would be far more stable in flight.
Kindest Regards,
Jack
[Updated on: Sat, 04 February 2012 12:09 UTC]
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| Re: WSF rocket, C size [message #43452 is a reply to message #43429 ] Sat, 04 February 2012 17:00 UTC |
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I used to do a lot of model rocketry when I was younger, so I think I can give some useful feedback.
I have tried a long-tail design similar to this, and I found it very unstable. My assumption was that the dragging fins would straighten the path, but in practice the rocket waved back-and-forth and turned nearly horizontal by the time the motor quit. I would make the fins shorter and have your rocket body tube at least 10". You are gluing a regular tube between the nose and frame, right? A rocket as short as the one shown will be so unstable it will probable make several loops. This is sort of a dangerous design as shown.
The rocket motor will get very hot. It may bond itself to the frame, and possibly melt the holding tabs. The landing impact may deform the weakened frame around the motor. Using a shorter-burning motor will keep the temperature down.
The forward holding tab is very thin. It could fail, and the motor might just shoot through the top of the rocket. Make a 2mm ring around the top to hold the motor and reinforce the frame.
Expect some of the ejection charge gases to leak out under the body tube and leave powder burns on the frame and nosecone. Seal them with spray paint to make it cleanable.
Your guide tube hole looks too wide. The rocket may be several degrees off from vertical before it even leaves the pad. Again, that is potentially dangerous. Add a guide tube at both the top and bottom of the motor frame, with tighter clearances. They can be short to save material. Consider adding a guide ring to the nose cone as well to keep it straight.
I have not flown a printed rocket because I now live in a densely populated area, but other than the issues I mentioned, I don't think you'll have any problems. It's pretty flexible stuff with some memory to recover from crashes.
Aaron - 40westdesigns.com/blog
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| Re: WSF rocket, C size [message #43467 is a reply to message #43429 ] Sat, 04 February 2012 23:10 UTC |
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Thanks for the feedback guys:)
I will take everything into consideration.
I wasn't intending to have any extra tubing on the rocket and my purpose in creating it was to make as smaller rocket as i could. I did make a rocket once that was very similar in design and it flew brilliantly, with a short body and long fins, true the body was slightly longer, the fins were longer and it had three fins instead of four but it seems similar enough to me.
I tested the rockets parameters in the nasa rocket modeler simulater and it flew slightly further than a standard rocket design (by about 3 feet, a total of 3030 feet)
The guide tube is 4mm wide in the hole and i thought it might be a bit small if i made it smaller, i do have concerns of the change of flight path due air friction on the guide tube, more than the length of the tube , i usually use drinking straws.
The rocket will be loaded with a small bit of wadding to stop the rockets backfire from burning the inside of the cone or body and will also have a primitive parachute or ribbon to slow the decent.
my main concern is the rocket flipping due to incorrect center of gravity. as of the danger of the first flight i will be launching it at the beach, away from everyone.. also the solid engine heating and fusing to the plastic is a problem ( will have to look into that) there should be enough of a lip at the top to prevent the engine flying straight out the top of the rocket:)
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| Re: WSF rocket, C size [message #43499 is a reply to message #43429 ] Sun, 05 February 2012 19:25 UTC |
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Great stuff. As long as it's done safely, experimental designs should definitely be pursued. My long-tail design (done in 8th grade) was only one sample point, and I certainly didn't simulate the design digitally (it was 1994), so hopefully your design does better. Let us know how it goes.
Btw, you could always put another tube on the other side for symmetry.
Aaron - 40westdesigns.com/blog
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| Re: WSF rocket, C size [message #43580 is a reply to message #43429 ] Tue, 07 February 2012 00:46 UTC |
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I have had a lot of great feeback from the rocketry association, and some great ideas and improvements.. once i have modeled them i will upload:)
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| Re: WSF rocket, C size [message #43602 is a reply to message #43429 ] Tue, 07 February 2012 07:25 UTC |
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cool, yes i was looking at you video a few days ago, its awesome. looks like a lot of work went into that, how does it fly outside? .. i have been wanting to convert one of my scalectrix cars to rc by modeling the needed parts:)
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| Re: WSF rocket, C size [message #46575 is a reply to message #43822 ] Fri, 06 April 2012 10:19 UTC |
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have finally ordered my rocket, waiting for delivery, had to wait for a few different orders to save cash on delivery.
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| Re: WSF rocket, C size [message #46576 is a reply to message #46575 ] Fri, 06 April 2012 13:23 UTC |
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Awesome job! I'd be interested to see how it flies!
I don't think you have enough room for a chute. Most small rockets like this don't need any kind of recovery system, I think it should survive OK. You may want to have the nose cone pop off on an elastic cord so it doesn't fly straight down. Another option is to seal the nose cone and the motor will eject, and with it a lot of the weight. For this to work you don't want anything holding the motor in.
I would be a little concerned that WSF is a bit rough in texture and might not slip smoothly through the air. Perhaps a little sanding and painting might help?
Great design!
[Updated on: Fri, 06 April 2012 14:07 UTC]
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