What happened on Mike's rocket? It looks like one or more motors is/are burning on the ground next to the pad. And is that I see Joe putting a rocket on a rod? What's going on here....?

Doug

I think..... One lit....it took a hard right hand turn at the rail
and hit the ground just to the left of the trailer and bounced
past the trailer. Pretty spectacular. A couple of J350s at ground
level.

Thanks...those are great pix. I missed all the action on that crazy one...I was out hunting but watched it from the distance. Probably better that way!

That pic of Natalie and the Killer Whale is great! Tomorrow she's going to have great stories and pics to show Mom.

Geof

Nice pics, Mike S.

Mike K. ... The flight looked errr sub-optimal. 😯 When it's rebuilt, I suggest the following if going Aerotech motors again in a cluster:
1) Use Blue Thunder propellant - much easier to light
2) Lightly sand the ID of the grains. Leave the dust in.
3) Paint the ID of the top grain with pyrogen
4) Check and match your igniters resistance

or, skip all the above and cluster with Cesaroni ! They just go when you tell them to. Unfortunately, you'd lose your cool motor retention method, as they don't have a threaded front end.

I do hope you rebuild. That is a really cool concept rocket and I want to see it fly (up). 😉

Ken

Nice pics, Mike S.

Mike K. ... The flight looked errr sub-optimal. 😯 When it's rebuilt, I suggest the following if going Aerotech motors again in a cluster:
1) Use Blue Thunder propellant - much easier to light
2) Lightly sand the ID of the grains. Leave the dust in.
3) Paint the ID of the top grain with pyrogen
4) Check and match your igniters resistance

or, skip all the above and cluster with Cesaroni ! They just go when you tell them to. Unfortunately, you'd lose your cool motor retention method, as they don't have a threaded front end.

I do hope you rebuild. That is a really cool concept rocket and I want to see it fly (up). 😉

Ken

It was spectacular to watch and I'm really glad no one (or the trailer) got hurt. All good advice, unfortunately, (I did sand the inner dia but have no pyrogen) I'm not sure if I want to build it again, unless there is a sure-fire reliable way to get the motors to ignite so that the rocket does not experience asymetrical thrust. I had asked for help getting some hot igniters, but it didn't work out, so its my fault for launching it. I'll continue this on the build thread I started.

Mike, are you absoultely certain on the CG/CP? it is so very hard to figure on a complex build like that... all the motors pull the GG way back.

Regarding instant ignition - the Cesaroni loads are the ticket.. that pyro disc means they will absolutely go. There is a reason they are lit with a single ematch. I've seen outrageous clusters of Cesaroni loads, and they always seem to light.

JW

Mike, are you absoultely certain on the CG/CP? it is so very hard to figure on a complex build like that... all the motors pull the GG way back.

Regarding instant ignition - the Cesaroni loads are the ticket.. that pyro disc means they will absolutely go. There is a reason they are lit with a single ematch. I've seen outrageous clusters of Cesaroni loads, and they always seem to light.

JW

I Rocksim'd it out (version 9) which allows side pod designs. With the sutainer attached there is all sorts of weight forward and it gets better with the K700's. The whole thing weighd 16 lbs, (9.5 booster, 6.5 sustainer). However, if I do it again I'll probably put larger fins on the cradle. One J350 motor was not fast enough off the rail (which I modeled in rocksim). One K700, yes.

What happened on Mike's rocket? It looks like one or more motors is/are burning on the ground next to the pad. And is that I see Joe putting a rocket on a rod? What's going on here....?

Doug

Here's a very short video. The flight took only 5 secs. You can increment it frame by frame and see what was happening. The cameraman was diving for the ground, but Mike S's picture pick up where this left off. Visit my other thread for more discussion and an event sequence of pictures

http://www.telerover.com/rockets/CR/GoH_Launch.MOV

Here's a very short video. The flight took only 5 secs. You can increment it frame by frame and see what was happening.

Its hard to tell from the video if its a stability problem or just the off axis thrust. I've had difficulty getting both of my Freeze Frame's booster motors to light simultaneously (even with Pyrodex pellets and Pyrogen coated fuel grain in the top) but the thrust to weight ratio of one outboard motor to the rockets weight was no where near yours. They didn't do somersaults but a noticeable non-straight trajectory. BTW, Pyrodex pellets do guarantee ignition but not necessarily simultaneous ignition...

Definitely more work needs to be done in this field. I won't say I've retired the big Freeze Frame but its been benched until I can do more research in simultaneous motor ignition. I've considered bolting down the rocket and releasing it with an exploding bolt mechanism until all motors are ignited. Perhaps not practical for your two stage design but its an idea for big load lifting rockets.

Doug