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horsefish

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Well, it had to happen sometime. I'm just bummed it happened on the maiden voyage of this great looking 3" diameter scratch built rocket. Flew it on an F50-6T motor and it started out awesome. Was with my father in-law, wife and kids at his farm, and when that thing took off, it got a big WOW! from everybody. Great flight, slight cock into the wind after it gained some altitude, eased over at apogee and looked like the ejection should hit right on time. Started down, and down, and down and uh-oh! After inspection, it looks like the ejection charge fired, but was very weak. There was very little residue in the baffle mesh (Aerotech style baffle) or in the body tube and about half the paper 'cap' was still on the top of the motor. I don't feel that the nose cone and chute were too tight, and I do feel that the 6 second delay time was correct based on when it reached apogee. As for the damage, it is pretty much totaled. The nosecone was pushed back into the upper body tube and about two-thirds of the shoulder of the nosecone is crumpled. I may be able to cut this off and use a bulkhead to salvage the nosecone. Upper body tube, and coupler are trashed. On the plus side, my fins held up well. :D This being my first larger rocket and first time using epoxy, I was impressed with the way the fins held together. The fin can may be able to be salvaged, but I am not sure there is enough of it left above the fins/upper centering ring to add a coupler to repair. Anyway, guess it's time to call Ross at Magnum and rebuild. The worst part is, the only pictures I will have are after the crash. I didn't take any before I flew it 'cause I didn't want to jinx it. :rolleyes:

Bob
 

n3tjm

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How chared is the epoxy bulkhead on the spent motor. If you can see a lot of red, that suggests that the charge may of leaked out (or the motor never had a charge). That is what did my IQSY Tomahawk in.. an E30-7T had no ejection charge :(. I lost the motor before I could send it and the rocket back to Aerotech for replacement.

If it looks like a weak charge, or no charge, return the spent motor to Aerotech. They MAY replace the motor for you.
 

horsefish

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doxiedog315, I'm sure I can rebuild, it may just be with all new parts. :D

n3tjm, is the bulkehead you're talking about, just below the paper cap in the top of the motor with a small (3 or 4 mm maybe) hole in the middle? If so, I don't see any red and it looks a little chared, so it looks like there was a charge. There is some, although not much, residue in the baffle mesh as well (I took it out to examine it). I was concerned about the possibilty of the baffle resticting the ejection, but I was able to blow through the back end of the rocket and it is not at all restricted. Since the paper that caps the ejection charge was not detached from the motor and about half of the paper cap was still in the end of the motor, it makes me think I just got a real whimpy ejection charge.

I will send it to Aerotech and see what they say.

Bob
 

llickteig1

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I've had this type of failure before on a 'large' diameter (3") rocket with E or F motor. I have theorized that it was possible that there was borderline just too much volume to pressurize and the ejection charge wasn't sufficient to pop the nosecone. Also, perhaps Aerotech got a little stingy with the BP or something as well.

Tell us more about your rocket. How long is/was it? Do you have any photos? I have a couple of ideas for you based upon the overall size and design of it.

--Lance.
 

llickteig1

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Bob,

Another question I have for you is this: Did the motor light right up and take off or did it chuff on the pad? That is, did it take it several seconds of smoking and puffing before it pressurized and lifted the rocket?

--Lance.
 

horsefish

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llickteig1 - The Rocket was was 3" diam. and with a body and fin can length of about 24 inches or so and a LOC nosecone that I think is around 10 inches long. Basically kinda short and fat. The motor tube was 10 inches long, so that helped decrease the volume as well. I tested the fit of the nosecone while building and prior to launch becuase I was concerned with the volume of space to be pressurized. I was able to blow through the rear of the Rocket and blow the nosecone off. Now I can be full of hot air sometimes, but I think an ejection charge should be able to provide more kick than I can. It is possible that the ejection charge itself was good and I just got a bonus delay and it never fired until it hit the ground. We couldn't actually see it land, because of the slope of the field, but I do know the nosecone never made it out. It was pushed all the way down the split apart body tube. Unfortunately no photos. I didn't take any prior to the launch, so as not to jinx it. That worked well huh? :D

The motor did not chuff at all. I was kind of surprised and was expecting a little trouble geting the F50 to go. I hit the button and it was off, no hesitation whatsoever. It was a really strong, fast, straight flight. Other than the ejection failure, it coudln't have been better. Oh well, half the fun is in the building, so I get to have some more fun now. :cool:

Bob
 
A

Austin

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Horse...sorry to hear about the bad luck...been there and it isn't pretty.

Carl
 

llickteig1

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Bob,

Sounds like you considered everything I had in mind. I guess this one gets chalked to "stuff" happens.

Since you've told us about this rocket, you are now bound by unwritten TRF rules to post photos upon rebuilding it. :)

Good luck, --Lance.
 

rstaff3

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Originally posted by horsefish
Well, it had to happen sometime. I'm just bummed it happened on the maiden voyage of this great looking 3" diameter scratch built rocket. Bob
"Only the good die young...."

Such problems are part of the hobby, good luck with the reapirs.
 

horsefish

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Well, I tore into the remains yesterday to see what could be salvaged. The fin can was solid but not enough body tube left to connect a coupler to. Using the dremel, I have cut away most of the body tube from the old fin, motor mount, centering ring assembly, and should be able to use this to slide into slots in a new airframe. I was able to cut the crumpled bottom of the shoulder off the nose cone and will epoxy a bulkhead plate to it with an eye bolt for the shock cord. Shock cord, chute and nomex were undamaged. All told, I should be able to get it back in shape for about 15 bucks or so, so not too bad. Also, I needed to go visit Magnum anyway to pick up a couple of motors for the wifes Mustang, so I will just get everything at once. Closer analysis of the pieces has not led to any more info on the cause of the ejection failure, so I guess I will just stick with very weak or very late ejection charge.

Bob
 

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