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AIM-9M or X? And Level 1 Q?

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davalf

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Has anyone ever made a full scale rocket of the AIM-9M or X? I was just looking at these missiles at work and thought they would be fun to build. I was wondering how the forward missile fins would effect it. Not just the weight but aerodynamicly.

Also, I am going to build a rocket for my level 1 at the begining of next year. I am going to use a design I built about 10 years ago. The rocket will be 4" in diameter for the first 30" and then 3" for the next 26" or so. With a total of 72" give or take. Back then I used centering rings to mount the 3" into the 4" and used an automotive funnel shaved down for the transition. With motor ejection this worked well having the nose cone come off for the recovery.
This time I plan on using a solid reducer from PML for the transition. This will have my parachute coming out of the bottom half of the rocket. Which will not be a problem for now. But some time in the future I would like to set this rocket up for dual deployment for higher altitude flights. Any suggestions?

Thanks
Dave
 

luke strawwalker

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Well, the forward fins complicate stability in ANY scale, so that's a given... there's a couple approaches one can use here... plenty of noseweight to move the CG forward, or mount the fins on 'axles' that can freely swivel in flight, which reduces the CP influence to the area of the fin in front of the pivot axle. There was an article I read awhile back (can't recall where ATM) about the Israeli dogfighting missile similar to the Sidewinder that has TWO sets of forward manuevering fins, which would make it TOTALLY UNSTABLE as a standard model rocket. The builder mounted the fins on pivoting axles and completely solved the stability problem-- as the rocket moves through the air, the fins 'self-correct' by swiveling in the airstream, which minimizes their destabilizing influence.

Maybe someone around here has a link to the story...

Good luck! OL JR :)
 

Handeman

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Forward fins move the CP forward. They are great for guided missles where they are the control surfaces. Not so good for model rockets as they require a lot of nose weight to get the right CP/CG configuration.

I think the 3" - 4" rocket can work quite well as a dual deploy. I would put the electronics bay in the transition with the ports for a baro altimeter about and inch or two above the actual transition. I would put a 54mm MMT in the lower 4" section. Even if you adapt down to 29mm, the big MMT gives you a lot of great options. You should be able to keep the weight with electronics and recovery below six pounds. This should fly quite well on H and larger motors. An I284W 38/600 motor would make for a great L1 cert flight. You could also do L2 on that and probably fit small L motor in it. I would glass the tubes and fins if you want to go that big.
 

davalf

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Forward fins move the CP forward. They are great for guided missles where they are the control surfaces. Not so good for model rockets as they require a lot of nose weight to get the right CP/CG configuration.

I think the 3" - 4" rocket can work quite well as a dual deploy. I would put the electronics bay in the transition with the ports for a baro altimeter about and inch or two above the actual transition. I would put a 54mm MMT in the lower 4" section. Even if you adapt down to 29mm, the big MMT gives you a lot of great options. You should be able to keep the weight with electronics and recovery below six pounds. This should fly quite well on H and larger motors. An I284W 38/600 motor would make for a great L1 cert flight. You could also do L2 on that and probably fit small L motor in it. I would glass the tubes and fins if you want to go that big.

I was planning on using G10 fins for this build. I used them in the past and was pretty happy with them.
 

Viperfixr

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Has anyone ever made a full scale rocket of the AIM-9M or X? I was just looking at these missiles at work and thought they would be fun to build. I was wondering how the forward missile fins would effect it. Not just the weight but aerodynamically
I've looked at AIM-120Cs and AIM-9Xs at 'work' and wondered about scratch building one of them too!

I even considered taking a set of -120C or 9x fins to a copier to get the shape/size right. All the -120 kits out there model the A/B models, not the slim C model. -120C would be about 7.5" diameter to be scale, and almost 12' long--sounds like a good L3 rocket! Or, just over half size with a 4" or 5.5" body tube.

9X would be great at 1/2 scale using 2.5" body tubes and 60" long--great 54 or 38mm rocket. I think I'd cheat just a smidgen on the size of the forward fins--shrink them just a little bit, and make them thin/light too. Of course, the thrust vectoring aft end would be a challenge!
 

cjl

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I've looked at AIM-120Cs and AIM-9Xs at 'work' and wondered about scratch building one of them too!

I even considered taking a set of -120C or 9x fins to a copier to get the shape/size right. All the -120 kits out there model the A/B models, not the slim C model. -120C would be about 7.5" diameter to be scale, and almost 12' long--sounds like a good L3 rocket! Or, just over half size with a 4" or 5.5" body tube.

9X would be great at 1/2 scale using 2.5" body tubes and 60" long--great 54 or 38mm rocket. I think I'd cheat just a smidgen on the size of the forward fins--shrink them just a little bit, and make them thin/light too. Of course, the thrust vectoring aft end would be a challenge!
Agreed - I like the 120C. I have a 4" scratchbuilt that's pretty close to perfect scale. It was my L2 rocket actually :)

If you work with AIM-120Cs, could you tell me if this looks about right to you? I had to go mainly off of relatively poor documentation and images that I could find online.

 

davalf

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When I get a chance I will take some pics of the 120 and the 9M/X.
 

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