Project Red Queen: It has begun!

[Marc_G]

OK, I totally obsessed about this. I ran back downstairs, threw on some gloves, and wiggled the clip into place before the epoxy set up (and before my wife got annoyed with the kids). Now I have to rush to work!!

 

[Marc_G]

Here's a picture of the clip I put in:



And another with the 18" chute attached via a Kevlar string to the clip, with the ejectable motor section attached to the Kevlar shock cord.



It will be ready for flight, after doing some final balancing:

 

[Marc_G]

OK, I'm balancing this with some additional nose weight. Final prepped for flight weight was 267 grams (including D12-3 and orange spacer), and the position of the CG as measured gave me only 0.29 calibers of stability. That puts me in the no-fly zone.

I need to move the CG up about 2 inches, which would give me a 1.34 caliber stability, though I may have to iterate a bit depending how much weight I need to add. Will report back when I've got it sorted.

Edit: OK, just over an ounce of clay packed into the nose gives me a liftoff weight measured at 297 grams and moved the CG forward about two inches. Rocksim reports stability of this configuration at 1.30. It should reach about 350 feet, ejecting right before apogee.

I now await a launch window...

 

[BABAR]

Beautiful Bird!

 

[BABAR]

I noticed this is rear eject. Are you flying on a grass field? I ask because it seems like the probability of hitting a rock or asphalt seems directly proportional to the quality of the finish in the rocket (in this case, probability is about 100%!)

In discussion of the upscale Gyroc, wondered about the possibility of a "nose cozy" shaped out of plastic like that on a nerf football. On your bird could potentially have two advantages. You need the nose weight anyway, and would protect that "umbrella" from untoward events.

 

[Marc_G]

I usually fly over grass but of course the asphalt paths and few areas of concrete act as attractors, amplifying damage.

I'm considering a nose cozy (great term) already. Don't want to mess up drag characteristics but have a few ideas...

 

[Marc_G]

(for when a single facepalm isn't enough)

Well folks, my design has proven its stability. It roared off the pad despite 5-8 mile per hour winds with only the most minor weathercocking.





(sorry about picture quality... rather than do high res pics every tenth of a second I opted for lower res video, to capture as much of the action as possible in case it was unstable... wanted to see how it performed, more than get crisp pictures of the decals as it went up)

Ejection was right at apogee. That's when things went pear-shaped.

It was immediately apparent that there was a critical failure. In that sick half second after ejection, I had several images, all jumbled in my mind as memories:
-The tailcone-motor mount assembly shooting farther out than the shock cord should have allowed.
-The parachute, apparently drifting with no weight attached
-The main part of the rocket, arced over and accelerating with a sick whistle sound.

Here is video, again with apologies for quality and probably wrong settings:

[YOUTUBE]6plGgOQzDh4[/YOUTUBE]

And the aftermath:




I request a moment of silence for the Queen's passing.

Now, all is not quite so grim as it would seem. First, the design is proven stable. It will be rebuilt.

But first, I will do some surgery and cut away the shredded body tube and create a frankenQueen with coupler and new tubing. The two lost fins, which are intact, will be reattached. I will redesign the attachment point for the shock cord and parachute. Notice in the picture above, the steel leader was ripped off at both attachment points, so severely that it destroyed the point where I attached the chute.

Truly an epic fail. The sad part was I had every intention of putting in a backup chute for the first flight, just in case something like this happened. In my haste and family distraction I neglected to do so. Oops.

So, I will do tests including perhaps a static test to ensure I get the ejection part right, then it will fly again. When I'm sure of my overall design, I will rebuild from scratch.

The Queen is dead. Long live the queen!

Marc

PS: The nose cone had hardly a scratch, thank goodness! It will be moved to the new rocket.

 

[qquake2k]

Oh man, I'm so sorry to see this. But it was a great up.

 

[BABAR]

In the words of ET, "Ouuuuuuuuuuuuuuch"

Some things even a nose cozy would't have helped!

Nice stable boost.

 

[Marc_G]

Yeah. I'm sad about the destruction but looking forward to getting the ejection / recovery right, then building again. And I have the nose and tail cones, which were > half the work, together. The rebuild should not be too difficult.

 

[Marc_G]

Hi everyone,

I've repaired Project Red Queen and she will be flightworthy once I perform a new attachment point on the tailcone/mount:



After cutting away the crushed forward tube, the remaining body tubing was significantly out of round, due to the trauma of impact, crushing, and ripping off on impact of two of the fins. I pushed the tail cone into place in the back to support the tube, and inserted the balsa nose block into the forward end (which ends right at the foreward end of the strakes). I let it sit overnight.

Then, I used some slightly diluted Carpenter's wood glue and painted the areas of the aft body tube where the fins had been ripped off. The thinned glue soaked in greedily. After it had hardened overnight, I removed the tail cone and the aft tube was holding a round shape.

I also glue-painted the fins that had ripped off, specifically the paper still attached to the root edges, with the thinned glue. This soaked through the paper to the original root edge wood glue. After drying, the paper still attached to the root edge was very stiff and strong.

I then completed a double glue bond for the fins by coating both surfaces with wood glue, smoothing it in with my finger, and holding the pieces together. I squeegeed the excess glue out from under the paper flaps still attached to the fins, using lots of pressure to hold things together while the glue set up. The tailcone was inserted prior, to give support and hold the round shape of the tube.

I used a 4" coupler, inserted into the foreward end of the remaining rocket (using epoxy, to avoid grab), and put a 12" section of body tube on it. No problems with out of round, due to the stiff coupler material.

I also reglued in the nose block, into a more forward position, to give additional pressurization volume inside the bird and hopefully reduce the shotgun ejection effect a bit.

The picture is shown with a new nose cone. The original painted one is OK, just needs buffing, but for test flights on this repaired bird I will use a new cone (that, if it crashes, I don't mind...).



Marc

 

[BABAR]

You could argue she'll look bit more realistic with some battle scars anyway!