AeroTech Redline HPR Motors

[G's Monster Rocket]

We are relatively new to HPR sport launches. Been building hobby and MPR for a long time. First foray into large rockets we launched with a G67R-14 in a Zeus 4" LOC frame. Upon ignition, the delay charge lit up simultaneously to the core burn and pushed out the recovery system and top section of the rocket, causing the rocket to tumble immediately upon leaving the launch rail. OK, first time shame on us for maybe not putting the RMS together correctly. After several successful launches using G's, H's, and I's (yes, Cert L-1) we again attempted to use an A-T Redline I218R-14 in a 4" LOC IV, after certifying on an H170M-14 in the same rocket. The Redline I218 failed in the same fashion as the first G67-14 with the ejection charge blowing out the top of the rocket and ejecting the parachute before the rocket left the launch rail. Immediate fail upon leaving the rail. We also tried a Redline I218R-14 in a 2.6" LOC Frame . Same result but this time the rocket reached about 200 ft before the Redline grains blew out the side of the 360 A/T motor case and "offed" one side of the rocket mid-flight. 3 out of 4 Failed

Just wondering if anyone else has had this experience with REDLINE MOTORS???

 

[Banzai88]

I launch almost exclusively reds, and other than an occasional chuff, I've never had one fail, and certainly nothing like you experienced.

Without post mortem pictures of the delay grain, it might be hard to say what's happened.

 

[dhbarr]

The first two sound very much like a loose delay grain.

 

[mikec]

IIRC, the biggest problem with Redline historically was that the propellant somehow interacted with the delay grain in the package, causing it to not burn or burn more slowly than intended, leading to very late or no ejection. This was solved by packaging the delay grain in its own bag and/or changing some formulation, only AT knows for sure.

Your first two experiences sound more like delay grain blowby caused by a loose grain or liner. If they're very loose on assembly, use masking tape to tighten them up.

The third one sounds like a grain void, which shouldn't be more common in Redline than any other propellant but does happen occasionally.

I don't fly Redline very often, I have to admit.

 

[WFWalby]

Flown many "Reds" in all sizes and never had a failure. Suggest you allow a very experienced motor builder watch over your shoulder the next time you build one to make sure you're not missing something. I'm not saying you are, but that many failures suggest systemic errors either on your side or on the AT side. Once you've verified the problem is not with assembly then contact AT with the mfg codes of your specific reloads and let them know they may have an issue with manufacture.
Good Luck getting your issue figured out.
William
PS. I was fortunate to have Karl Bauman (AT VP Warranty & Tech Support) as a mentor and as a Certifying Witness on all 3 cert levels so I was schooled by the best. Very early on he caught a couple mistakes that could have been detrimental to my flights.

 

[tsmith1315]

You should contact Karl: [email protected]

We have a thread that’s monitored by Aerotech for questions and communication:
https://www.rocketryforum.com/threads/aerotech-open-thread.125657/page-195#post-2345274

 

[loopy]

Flown many reds from G-J, and haven't had any issues with any of them. Very odd...Definitely check fit and finish of the delay trains and make sure the o-rings are all the right ones in the right spots.

 

[waltr]

The premature ejection sounds like a failure of the Delay O-ring and/or improper assembly.

One issue is the possibility the the grain liner was too tight and did not easily slide forward when tightening the aft closure. This prevent enough pressure on the forward grain O-ring and the Delay O-ring which then allows propulsion gases to get past the O-rings into the ejection charge.
If the grain liner. does not easily slide into the case then peal off a layer until it does.

Second cause may be due to the grain liner being too short. Again not causing the O-rings to properly seat.
This one is hard to catch while building the motor. Seems to be rare but reports indcate it has happened.

I also have flown a number of G76's in the 29/40-120 case without any issues.
I haven't had premature ejection in the 29 case but did on the 18/20 case until I found I did not propery clean the frd closure which resulted in the delay O-ring not properly seating.

At the last local club launch someone had premature ejection with a 29/40-120 case. Found that the fwd closure had bad threads and was not fully seated therefore the delay O-ring was not seated.

Other posted good suggestion and worth contacting AT.

 

[Banzai88]

http://www.motorcato.org/

 

[firemanup]

Flown reds all the way up to M1550 and have never had an issue.

First two sound like the top end wasn’t built correctly. Delay grain spacer or o ring placed incorrectly possibly.

What club do you launch with?

 

[TheTank]

Love the reds. Flown them up to Ms with no issues like you have experienced.

M1550R

 

[G's Monster Rocket]

Flown reds all the way up to M1550 and have never had an issue.

First two sound like the top end wasn’t built correctly. Delay grain spacer or o ring placed incorrectly possibly.

What club do you launch with?

We’ve flown with the superstition space society and the Kingman Rocketeers, both from Arizona.

 

[G's Monster Rocket]

Love the reds. Flown them up to Ms with no issues like you have experienced.

M1550RView attachment 546616

Initially we loved flying the Reds, until we started having problems. No doubt, assembly issue and probably the spacing and pressure issue against the forward spacer and O-ring seal on the front closure. Blow by. Will try it again next weekend and see how it goes. The picture I attached is the only successful redline launched so far for us. Thanks for all the comments and the help.