Estes A8-0 Burn-through side wall on ejection end.

[Fud91]

Just curious, but has anybody seen this happen to an engine casing before? Used this to launch my two-stage Vigilante this weekend.

I didn't have a true "upper-stage"/purple labeled engine, so I was using a green-labeled C6-5 in the second stage. Would that have anything to do with it? Not sure if the nozzle diameter is different (so that the upper stage engine catches more of the ejection charge from the booster) between "purples" and "greens". If so, maybe that had something to do with this burn-through on the side of the casing?

No damage done, but I did see the flame shoot out to the side during the second stage ignition. I've never seen that happen before. Manufacturing date was 4/14/11. This was the last of a 3-pack I used. Other 2 engines burned fine.

Thanks in advance.

 

[mikemech]

Haven't seen that one before.
I belive that the nozzles are the same on all Estes C6-x motors.
The damage looks more like a burn from the second stage motor. You said no damage. Was there any scorching on the booster tubes? Possible nozzle damage on the second stage motor could angle the exhaust jet. Was the flight straight? Or the booster could have stuck and cocked for a bit allowing the flame to hit the booster motor.

 

[shreadvector]

There is no ejection charge in a booster motor.

Nozzle size is only an issue if the booster nozzle is MUCH larger than the upper stage and the thrust from the upper stage can flow through the booster motor and not create enough pressure to seperate the stages. Like if you had a D12-0 booster and an A3-4T in the upper stage.

O nly difference in a C6-5 with a green label and a C6-7 in a purple label is the C6-7 has 2 seconds more delay time before ejection and they changed the color of the label to give you a visual clue in case you might make a mistake. MANY multi-stagers fly better with a medium delay in the upper stage.


The only way to burn the casing like that is to have the upperr stage motor thrusting into it for some non-tiny time period (like .5 or more seconds?). A motor will cut through steel like a cutting torch, so charring cardboard is no problem.

Was there damage to the booster stage? Did the stages stick together for a bit, instead of INSTANTLY popping apart when the upper stage motor ignited?

View attachment 171320

Just curious, but has anybody seen this happen to an engine casing before? Used this to launch my two-stage Vigilante this weekend.

I didn't have a true "upper-stage"/purple labeled engine, so I was using a green-labeled C6-5 in the second stage. Would that have anything to do with it? Not sure if the nozzle diameter is different (so that the upper stage engine catches more of the ejection charge from the booster) between "purples" and "greens". If so, maybe that had something to do with this burn-through on the side of the casing?

No damage done, but I did see the flame shoot out to the side during the second stage ignition. I've never seen that happen before. Manufacturing date was 4/14/11. This was the last of a 3-pack I used. Other 2 engines burned fine.

Thanks in advance.

 

[Fud91]

I think you two may be on to something here, now that I think about it. I only had cellophane tape wrapped once around the two motors to connect them, but I think your theory about them sticking together for a short period of time upon second stage ignition may be the answer. I seem to remember a bit of a "cant" by the rocket assembly right at second stage ignition (which would make sense if there was a bit of drag cause by the engines not completely separating). The upper stage righted itself immediately and then flew perfectly from there.

No damage to the booster stage either.

Good stuff guys! Think you figured it out for me - learned something new!

Thanks!