tonights Mongoose launches

[caheaton]

Headed out to the local park again today. Had planned on trying the Spirit again on the B4, but never got around to launching it after flying the Mongoose a couple times. Both launches used a B6-0 to 1/2A3-4 (in adapter...I wish they'd bring back the 1/2A6-4) pairing of engines. The first launch was picture perfect...rocket flew straight and true with staging at what to my eyes looked to be 50 ' ~ 100' (but I'm terrible at eyeballing altitude from nearly below the rocket). Openrocket predicted an altitude of around 319' which looked to be about right. Very light wind (about 3 mph) carried rocket about halfway across launch field. Unfortunately, the booster sustained a major crumple upon landing, which affected the next launch.

Rather than launching the Spirit, I hoped for a repeat of the Mongoose flight. I prepped again using the same types of engines, but had to use tape to hold the stages together as the crumple was keeping it from mating properly and the 13mm engine didn't seat all the way into the adapter (I suspect due to carbon from prior motor). Against my better judgement, I launched anyway. The rocket left the rod and arced over at about 30 degrees (likely from the tube crumpling). Separation occurred at about 50' and halfway across the field. I recovered the booster and thankfully the upper stage landed right on top of the berm that separates the park from the neighbor's back yards. . Launch was successful, but not nearly as satisfying as the first launch.

Looks like I'll be rebuilding that booster before flying the Mongoose again....(luckily I have the parts laying about).

Craig

 

[Dotini]

Headed out to the local park again today. Had planned on trying the Spirit again on the B4, but never got around to launching it after flying the Mongoose a couple times. Both launches used a B6-0 to 1/2A3-4 (in adapter...I wish they'd bring back the 1/2A6-4) pairing of engines. The first launch was picture perfect...rocket flew straight and true with staging at what to my eyes looked to be 50 ' ~ 100' (but I'm terrible at eyeballing altitude from nearly below the rocket). Openrocket predicted an altitude of around 319' which looked to be about right. Very light wind (about 3 mph) carried rocket about halfway across launch field. Unfortunately, the booster sustained a major crumple upon landing, which affected the next launch.

Rather than launching the Spirit, I hoped for a repeat of the Mongoose flight. I prepped again using the same types of engines, but had to use tape to hold the stages together as the crumple was keeping it from mating properly and the 13mm engine didn't seat all the way into the adapter (I suspect due to carbon from prior motor). Against my better judgement, I launched anyway. The rocket left the rod and arced over at about 30 degrees (likely from the tube crumpling). Separation occurred at about 50' and halfway across the field. I recovered the booster and thankfully the upper stage landed right on top of the berm that separates the park from the neighbor's back yards. . Launch was successful, but not nearly as satisfying as the first launch.

Looks like I'll be rebuilding that booster before flying the Mongoose again....(luckily I have the parts laying about).

Craig

I've got an unbuilt Mongoose kit hanging on my garage wall, and in preparing to build it, was reading some reviews. Several mentioned a possible defect in the strength of the tubes, and others spoke of unclear instructions. In your experience with the Mongoose, have you noticed these or any other problems? By chance, do you have a measurement of the completed weight of your model? In your opinion, is there any way a successful launch could be accomplished with an A8-0 booster? (I was reading in some older Estes catalogs, and learned that at one time the A8-0 was rated safe for a 4 oz. lift.)

Thanks for any comments you'd care to make!

 

[caheaton]

Sorry, I don't have the completed weight. I could probably get that for you (but first will have to recover the discarded booster from the trash ). My biggest issues with the model are: booster tends to land "fins up", which crumples the body tube where it mates to the upper stage. It's also a bit of a pain fitting the stages together, as it relies upon the engines taped together to hold the stages together, and the engines friction fit into the boosters. It's all fine except it can be a pain holding it all together, especially after you invert the rocket to insert the ignitor, which is recessed a bit due to the engine block behind the booster engine. If you tape isn't the stickiest, it can tend to fall apart during prep.

As far as A8 booster motors, you can try but be sure you're WELL away from any houses and property with a large field. I tried mine with an A10-0 motor in an adapter and the flight profile was such that the rocket boosted to about 15 to 20 feet, hesitated, and then the upper stage kicked in. By this time the rocket had tilted a bit so it then flew at about a 30 degree angle to the ground. It was recovered safely, but would have been scary if any houses or other property had been nearby. The B6 booster is more reliable and when I wanted to fly low I would combine it with a mini engine 1/2A (using an adapter) in the upper stage.

Overall, rocket is okay but I much prefer a design that uses a coupler for connecting the stages together.

 

[Antares JS]

I have had a similar issue with the Mongoose booster landing fins-up and crumpling the tube. I would suggest buying a length of BT-50 coupler long enough to reinforce the entire length of the booster tube.