Two motor failures yesterday....

[burkefj]

Yesterday I was doing some flights at a new club, flew my large X-15, ALCM, Interceptor and a new Bomarc.

I had a G-40 single use blow the aft end off on ignition using a copperhead in my X-15, split the case it was stuck into the motor mount tube really tightly. I've had this happen a couple of months ago on two G-38's but the first time on a G-40, failure mechanism looked identical in all three of them. I'm really bummed, don't know if I will trust any of the single use motors any more.....These had the ejection charge removed but nothing else altered, were bought new and not abused.....case looked intact when I loaded it. Nozzle was not plugged on retreival. Fortunately it extinguished itself when it spit the nozzle/propellent out the back.

Then I had a great flight on my Interceptor on a G-12. Reloaded the casing and flew my new bomarc that weighs the same. That was a maiden, the liftoff started the same and then seemed to have about 3x the accelleration, the bomarc shredded and the casing flew out and went missing in the adjacent freshly plowed field. I wasn't able to recover it and in the video was hard to tell because the accelleration caused it to go out of frame. I can only assume that there was a void in the propellent and I got a sudden increase in burn area....I guess I'll have to weigh my grains before loading from now on. I recovered the rear end and motor tube was intact so it didn't burn out the front end or cato, just didn't behave like an endburner, and it was only slotted on the end when I loaded it....The video sound seemed to indicate about a 3 second burn instead of 8.

wierd...

anyway, here are the videos of the flights that worked.....sigh.

https://www.youtube.com/watch?v=W0MZky_iMnc

 

[n3tjm]

Are you the one that wrote that sport rocketry article about making boost gliders out of foam? NICE FLIGHTS. Oh, I have seen G12 reloads come with the wrong nozzle, but in that case the G12 was more like a G6.

 

[burkefj]

Yup, that was me who wrote the article.



I have had some E-6 reloads that were made from blackjack propellent as an endburner by mistake that were like an E-1....they just sat and burned on the pad for a really long time.....

Frank

Are you the one that wrote that sport rocketry article about making boost gliders out of foam? NICE FLIGHTS. Oh, I have seen G12 reloads come with the wrong nozzle, but in that case the G12 was more like a G6.

 

[TheTellurian]

Yesterday I was doing some flights at a new club, flew my large X-15, ALCM, Interceptor and a new Bomarc.

I had a G-40 single use blow the aft end off on ignition using a copperhead in my X-15, split the case it was stuck into the motor mount tube really tightly. I've had this happen a couple of months ago on two G-38's but the first time on a G-40, failure mechanism looked identical in all three of them. I'm really bummed, don't know if I will trust any of the single use motors any more.....These had the ejection charge removed but nothing else altered, were bought new and not abused.....case looked intact when I loaded it. Nozzle was not plugged on retreival. Fortunately it extinguished itself when it spit the nozzle/propellent out the back.

Hi Frank

Not much on RCG so I'm lurking here, but aside from that I had a friend long ago that had the exact same result namely blowing the nozzle and propellant out the back. Seems he had missed the slot with the copperhead and was wadding the ignitor into the space between the nozzle and propellant. Result was exactly the same. Just a thought to check.


Richard

 

[burkefj]

It's an interesting thought, but I was pretty careful threading it in and usually pull it out part way to be sure it isn't bunched up as would happen if I had missed the slot....I may switch to the long quest igniters since I think they are overall a bit smaller just to be sure it isn't an igniter issue.

Hi Frank

Not much on RCG so I'm lurking here, but aside from that I had a friend long ago that had the exact same result namely blowing the nozzle and propellant out the back. Seems he had missed the slot with the copperhead and was wadding the ignitor into the space between the nozzle and propellant. Result was exactly the same. Just a thought to check.


Richard

 

[iter]

Sorry to hear about your motor trouble Frank.

Ari.

 

[Minimum_Wage]

Hi Frank,

Bummer about the lost casing. Can you go back and walk the field again to look for it? It always seems like a long shot, but I've actually been able to find both a keychain camera and an Rx battery pack several days after losing them in crashes.

The interceptor flight in the video was great!

Mike Mc.

 

[burkefj]

Unfortunately the club doesn't have permission to go into the adjacent field, so I'm out of luck.

Hi Frank,

Bummer about the lost casing. Can you go back and walk the field again to look for it? It always seems like a long shot, but I've actually been able to find both a keychain camera and an Rx battery pack several days after losing them in crashes.

The interceptor flight in the video was great!

Mike Mc.