Ye Olde Rocket Forum - Houston...you guys know the rest.

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- - Houston...you guys know the rest. (http://www.oldrocketforum.com/showthread.php?t=17839)

Quote:

Originally Posted by mwtoelle

A piston would help, but only the only people that I know that would use them are competition fliers. If the A10 was actually labelled to reflect the actual average of the motor, it would be an A2 instead. I have actually flown 1974 vintage A10-0Ts, and even those motors had a long burn. I even put a comment in my flight log about to A10-0T burning about as long as an A3 motor. In the Estes catalogs of the time it was claimed that the A10s had a 0.26 sec. thrust duration. Current catalogs show the A10s with a 0.80 sec thrust duration. Personally, I think that the A10 has always had the longer duration listed in the newer catalogs. Even the data from S&T concurs with the longer thrust duration. As I have learned over the years, long burn, low thrust motors and windy flight conditions do not mix very well.

That's too bad--competition flyers don't have any special DNA... :-) The fit of the blow-off tube of a piston launcher does have to be just right, but vented gap-staging (and the Centuri Pass-Port stages) also requires/required just the right fit (so that the lower stage burn-through gases can be vented to relieve the inter-stage pressure, without blowing the two stages apart before the upper one can ignite.

Quote:

Originally Posted by blackshire

Agreed, a piston would be helpful, but a piston launcher is tricky to use. The launch weight of a full-up Mini-Comanche-3 is the range of 2.2 - 2.3 oz. The problem with three stage model rockets is getting them safely off the ground with the motors that are available today. The Estes Farside/Farside-X, the Centuri T-Bird, and Centuri Arrow-300 were able to satisfy the demand for three stagers, but the demise of the B14-0 led to their being dropped. Even Estes decided to use D12-0s in their Comanche-3 to ensure a safer boost than was available in the older kits after the B14-0, B8-0, and C5-0s were discontinued.

Quote:

Originally Posted by mwtoelle

Clustering the first stage of the Mini-Commanche-3 (adding three--or even two [although it would look unsymmetrical, but it would fly fine]--13 mm booster motor tubes on the sides of the center tube) would greatly increase the first stage's thrust and acceleration, although clustering the igniters must be done carefully, and it requires more juice than a four-AA battery launch controller can put out. Another, simpler option for the Mini-Commanche-3 would be to make a BT-20 first stage, which would house a B6-0 or C6-0 booster motor (the A10-0T first stage could be used on dead-calm--or nearly so--days).

Wow. Thanks for lots of great feedback. Unfortunately, the steel rod was clean, as was the lug. Neither did I note much wind at the time of launch (I'm very wary of launching in wind.)

Some post-mort pics. The surviving first stage, seemingly undeterred.

I'm inclined, knowing the conditions at flight time, to think GH might be right. If the A10-0T does in fact have enough oompf to power the design, perhaps this particular A10 was a less than perfect product.

Our LCO is a Physics PhD. His immediate reaction was that it didn't have enough thrust.

Note the damage sustained by the second stage upon impact with the ground under power.

And the launch lug...

Is the A10 nozzle eroded? That would significantly lower thrust.

Maybe some impurity got into the BP during the motor making process and lowered the thrust.

It definitely looks a little different than most spent engines I've seen.

That almost looks as though the propellant was was damp.Definitely not good combustion.

Thanks, Jeffrey.

That was a new pack, kept in a cool, dry house and opened just before insertion.