Titan4

Inspired by the recent Cassini Huygens Project on the moons of Saturn, I have built an 8% scale Titan IV rocket complete with drop-away boosters. The Titan flew June 25th at Whitakers NC. After a spectacular liftoff the Titan veered right and broke up, here are the specifics:

First, thank you all for the excellent feedback on my recent "mishap". As I review all the pics and videos, I find several things that on their own, may not have had such catastrophic consequences, but together spelled doom.

There were 4 things I feel led to the catastrophic failure.

First, if you look closely at the 2nd pic in Mark Canepas' series (modernhpr.com), the right booster does not appear to be at full burn. The flame is not defined, not an hourglass like the others. With motors of this size that could mean a substantial drop in thrust on that side... so it starts tipping right. We used the best means possible to light them all in sync, and it appeared to do so, but something is amiss in the first few shots. Next time I will make the center motor much bigger than the outboards so a discrepancy in thrust will not have such a dramatic effect on the flight. (if that even was the case).

Second, the flag. Of course we should have removed it, and I won't even go into the discussion that occurred (one did) and how it was left there. I will never do that again. The flag clearly wedged between the booster and the main and went for a ride. Was the impact from ripping it loose enough to impact direction? I don't know, but it had to create some drag, and now it tips more to the right.

Third, on the upper right booster attachment point, where the flag has wedged, the shear pin placement was poor. It caught the very edge of the PVC coupler, not the center of it as designed. Why? I'm unsure, there was a lot going on in those last few minutes. It could have been a design or assembly problem, I'm not sure. You can see by the pics, even with that connection compromised, the booster stayed on a while. In fact, in pic 6 of Marks series, the booster nose appears to be several inches further away from the body than the left booster, pushed out by the flag probably, but it still hangs on. Clearly this adds to the problem.

Lastly, CG/CP. Determining the true CP was a guess. I did all I could but had little to go on. I had never seen anyone do this before, no articles on the web, so I just tried to get my CG as far forward as possible. It may not have been enough, though that nosecone/payload section was too heavy to carry alone while the main motor fin can was not.

Also, had I used a much heavier shock cord, it *might* have saved the main section. The 1" tubular nylon strap (40' long) was snapped when the main deployed at high speed. If it had not broke, and the bulk heads had survived, I would have only lost the boosters, a minor expense in comparison.

It looks unlikely that I will get any film from the Gun Cam (right side) so we may have all the evidence we're going to get. I'm very disappointed at the failure and truly appreciate all that helped me in this attempt. It was awesome, despite the result.

Will I try this again? Of course! Will it be totally successful? Maybe. I hope so. I've heard a lot of suggestions as to how it "should" have been done. Hopefully when I make my next attempt I can get more of that up front and avoid these mistakes.

I will be cleaning up my website and organizing the pics and vids this weekend. Thanks to all that have sent me stuff, you folks got some *awesome* shots! I'm impressed.

Thanks again, and let's get building!

Steve "Smash" Mashburn