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-   -   X-20 Dynasoar with titan II stack, RC flight success! (http://www.oldrocketforum.com/showthread.php?t=15145)

burkefj 06-14-2015 10:45 PM

X-20 Dynasoar with titan II stack, RC flight success!
 
5 Attachment(s)
Hi All, some of you may have seen my posting on trf but for those of you banned or otherwise non trf, I decided to share it here as well.

I had built a 30" long depron foam Dynasoar rc boost glider that I have flown many times on E-6 RC motors. It weighs 9 oz rtf.

I really wanted to try to make a full titan II stack and try to fly it that way. This was a proposed finned version for suborbital test flights that was never built. In my simulations, using normal highpower construction for the body, I would be at about 23# and the only motors suitable for it would be too fast and shred the glider. If I made the glider more robust it wouldn't fly very well. The booster was going to have to be 8" diameter and 7' long.

So I set out trying to see if I could use a 29mm center tube, 4" pml 10" long parachute bay and then use depron foam centering rings, interlocking stringers, 2mm foam skin, and carbon reinforced foam fins to try to keep the weight to 75 oz which would allow me to fly it on an H-97 and keep the speed to around 160fps.

I also built a fullscale Hellfire Missile that weighs 80 oz rtf for I-205 motors and a Jupiter C that is 7.25" diameter and 6' tall that flies on H-115 and H-129 motors as test vehicles for the structure.

I had to be creative on how the altimeter mounted in a separate section with a foam door, a channel to route the deployment charge, attaching the recovery harness to handle the load but not shed the foam structure, and consider landing loads etc.

I also had to set up the glider with mixing such that when the glider is on the nose the elevons work backwards since it is in a canard configuration with the stack so I can steer it on boost if needed, but when ejected and I switch to glide trim, they go back to normal direction.

The Nose cone is really a coupler with a cap that when ejected pulls the chute out and pushes the glider off of the carbon guide rods...

I got the chance to fly it this weekend, and given the sheer amount of things that could have gone wrong or failed, it was a miracle that it had a perfect flight, I was able to adjust pitch on boost slightly as needed, ejection pushed the glider off nicely and had a very nice recovery.

Here is a link to the construction, flight video and an onboard video showing the ejection of the glider and the chute on recovery. I had a bit of a head wind so I just hovered the glider down to a pancake landing in the alfalfa field. Thanks to the Blue Mountain Rockeers for the warm welcome and nice site.

https://www.youtube.com/watch?v=rJtHt7p-EKI

Frank

BTW, the jupiter C and Hellfire test vehicles flew great and held up fine.

burkefj 06-14-2015 11:03 PM

4 Attachment(s)
Here are some pre-flight and post flight shots, arming altimeter, with my son Max.

ghrocketman 06-14-2015 11:04 PM

Very cool project and videos.
Can it take more impulse such as a low-thrust/long-burn I motor ?

burkefj 06-14-2015 11:16 PM

It was built for a specific speed range and impulse. There isn't much point in putting a larger motor in it as it gets too high to see the glider well. From the video it is hard to see the real picture of what it looks like standing 300' away and when at apogee. Also, any weight you put in the tail needs weight in the top to compensate. I built the balast into the transition section so that it stays with the body and you don't have a heavy nose cone flying around trying to wrecking ball the body during recovery. I really had to engineer this to be as light as it is to fly on this motor. If I built it heavier for larger motors then you need a larger chute, larger chute bay, etc, it cascades...I can get by with a 48" chute for this rocket and get 12fps decent rate.

It has a 29mm motor and I don't know of any long burn 29mm I motors. a CTI H53 would be ok, and shows about 100 feet more altitude, but the exit velocity off of a 12' rail is still only 45 feet per second compared to 60+ with the H97. You'd be stuck with zero wind launches.

Quote:
Originally Posted by ghrocketman
Very cool project and videos.
Can it take more impulse such as a low-thrust/long-burn I motor ?

shrox 06-14-2015 11:21 PM

Like like like

Rich Holmes 06-15-2015 06:34 AM

OUTSTANDING! An accomplishment to be proud of.

BEC 06-15-2015 10:00 AM

Fantastic! And of course now I'm more than a little bummed that I opted to stay on this side of the mountains this past weekend to do other rocketry things (including hold my regular club launch) rather than come over to BMR for the weekend.

Congratulations on the successful flight. And yes - a great bunch of folks to fly with up there in the alfalfa.

Bill 06-15-2015 06:51 PM

I am glad people are learning to build light instead of just sticking a bigger motor in it.

Still a very small minority, though.


Bill

burkefj 06-16-2015 02:27 PM

5 Attachment(s)
Here are a few poor quality flight shots...

burkefj 06-16-2015 03:56 PM

3 Attachment(s)
Some from the onboard camera


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