Aerotech D10/21 and hibachi effect

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Bill S

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I've been considering using some Aerotech D10/D21 in a couple of my rockets. Once I started reading up on them, I kept seeing mention of people having rocket damage due to the "hibachi effect". Both rockets would be using 24mm engine mounts in BT-55 stuffer tubes in BT-70 and BT-80 body tubes. Does anyone have any thoughts on the likelihood of encountering such damage with that setup?

The first rocket is built already so it probably wouldn't be practical to remove the stuffer tube to replace it with a thicker-walled one. The second rocket is still in the design phase and could be changed if needed.

I guess I could just not use the Aerotech engines and stick with Estes D-engines, but I thought the Aerotechs would be a neat option to get some more altitude if wind conditions permitted.
 
I use Aerotech reloads in 18 and 24 mm motor sizes in various Estes rockets all the time, never had any problems with "hibachi effect". I think most of the rockets are the same outer body tube you mention.
 
The only time I had this problem it was with the C10. Because it was shorter than regular 18mm motors there was a gap between the top of the motor and the thrust ring. I suspect that the thrust ring helped to trap the hot gas in that space. (Because the delay is drilled to shorten it there can be quite a bit of delay left burning when it ignites the ejection charge.)

I didn't notice the problem until the body tube failed. Earning me a Best Midwest Qualified award at NARAM. (Not from the failure precisely but from splatting my egg next to some contest bigwig.)

You might see if you can find a coupler that is a few inches long and place that just ahead of the motor. When it starts to burn through you can replace it.
 
Bill S said:
What body tubes did the happen in?
Click to expand...

In my case, a BT50 minimum diameter rocket. I just put in a segment (about 1-2 inches) of BT20 well coated on the inside with epoxy and with two ar-2050 rings to serve as a engine block on the second version of it... air being a great insulator... it solved the problem. Yes it was friction fit... yes it went very very high! (You should have seen it go on a AT E15).

I know that the motor tube (say for a long BT50) will take a lot of abuse which is why if you don't do anything special, a heavy-duty 24mm motor mount tube is the way to go. I'd say if your bt55 stuffer goes several inches beyond the end of the motor, you should not see any roasting of the outside surface.
 
DeltaVee said:
I know that the motor tube (say for a long BT50) will take a lot of abuse which is why if you don't do anything special, a heavy-duty 24mm motor mount tube is the way to go. I'd say if your bt55 stuffer goes several inches beyond the end of the motor, you should not see any roasting of the outside surface.
Click to expand...

The rockets in question both have 24mm mounts, inside BT-55 tubes, which run the entire length of the rocket, so hopefully things will work out. I may look into beefing up the tube on the rocket I haven't built yet (still in design phase) just in case.

I am still very tempted to get those Aerotech D10/D21s just for the fun of it, before they become totally unavailable. :)
 
Bill S said:
I've been considering using some Aerotech D10/D21 in a couple of my rockets. Once I started reading up on them, I kept seeing mention of people having rocket damage due to the "hibachi effect". Both rockets would be using 24mm engine mounts in BT-55 stuffer tubes in BT-70 and BT-80 body tubes. Does anyone have any thoughts on the likelihood of encountering such damage with that setup?

The first rocket is built already so it probably wouldn't be practical to remove the stuffer tube to replace it with a thicker-walled one. The second rocket is still in the design phase and could be changed if needed.

I guess I could just not use the Aerotech engines and stick with Estes D-engines, but I thought the Aerotechs would be a neat option to get some more altitude if wind conditions permitted.
Click to expand...

I've used both Aerotech D10 and D21 in the same stock Estes V2 (24 mm with Estes Motor Adapter https://estesrockets.com/product-category/accessories-parts/engine-mounts/). No problem at all. Still ready to fly.
 
The only problem I've had is with a plastic motor retainer getting melted. I've never seen one get hot enough to do anything to cardboard, although I'm willing to believe it's happened.
 

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