Second high power flight

[Hugues]

I am thinking of flying my Madcow 2.6 cardboard DX3 (who flew great on an H135) with an Aerotech DMS I205W. Just to push and test the limit. I'm pretty sure the rocket is build strong enough to hold the stress but my concern is the close proximity of the longer motor 12" to the chute bundle (about 5" left - see picture). Any advice on that ? Thx

 

[Hugues]

Open rocket sim also show it should be fine with stability. Again my concern is the hot gas. Will it burn trough the chute protector and damage chute release. Pression is another issue but their is pressure relieve holes in that 5" space.

 

[Nytrunner]

Use an ejection charge calculator. (I like this one)

As long as you can sufficiently pressurize the bay volume (minus the long motor sticking into it), you don't have to have the entire load of BP. Make sure that chute protector is between the chute and ejection well, and wrapped around well.

 

[mbeels]

I'm curious, you mentioned a chute release, any reason in particular you separate the rocket in the middle, instead of at the nose cone? Does the parachute fill the top half of the rocket?

I've fired charges up against a nomex cloth and didn't have any burn through. The only damage I had once when the cap of a centrifuge tube physically punctured the nomex and caused a small tear. I guess that you may get more soot build up, and have more wear on the protector, but I bet it would work. To be safe, you could stuff some expendable wadding below the protector, it'll help the cloth last longer anyway.

 

[Nytrunner]

Speculation: It is a single deploy rocket with a bulkhead in the coupler to reduce body volume

 

[Hugues]

I'm curious, you mentioned a chute release, any reason in particular you separate the rocket in the middle, instead of at the nose cone? Does the parachute fill the top half of the rocket?

I've fired charges up against a nomex cloth and didn't have any burn through. The only damage I had once when the cap of a centrifuge tube physically punctured the nomex and caused a small tear. I guess that you may get more soot build up, and have more wear on the protector, but I bet it would work. To be safe, you could stuff some expendable wadding below the protector, it'll help the cloth last longer anyway.

The kit is made like that with the large payload section for dual deployment modification. I use mine as electronic bay. I build a tray and fix a gps tracker and altimeter on it. The nose cone can be remove with screw to access the inside.

 

[richP]

Simple answer, don't worry about it - just make sure the nomex is wrapped well.
To put your mind at ease, you could add an inch or two of dog barf between the motor and nomex.