The Incredible Aerotech E15-16

[rokitflite]

I built a beautiful upscale BT-80 variaton of the Centuri Scram-Jet. I waited over a year for the perfect day to fly it. The motor of choice was an Aerotech E15-4. The launch was totally cool. The motor sputtered on the pad a little before it roared to life, reaching apogee at about 700 feet. 1-2-3-4- Parachute? Nope-5-6-7-8-9-10-11-12- WHAM!!! -13-14-15- POOF! I now have what resembles a large, orange snuffed out cigarette butt with fins. Thank you Aerotech!

-Scott

https://members.aol.com/plorkk/scram

 

[sandman]

I've noticed...and experienced...a LOT of that!

The "bonus" delay.

sandman

 

[Fore Check]

Wow - beautiful rocket and tough story..........

 

[marvSRG]

Ahh the infamous bonus delay...bad with RMS 24mm D and E loads, RMS 29mm E's and F's, and the E15W. D21's too. It happened to me in my Phoenix, but luckily it ejected in time. It didn't matter though because it separated and was damaged anyways. I think this happens especially with the shorter RMS D's and E's. When you have loads with those short grains that are loaded at the bottom of the case, you always seem to have delay problems. I never thought the short grain reloads (like the 24mm D's and E's, and 29mm E's and F's) were very reliable delay wise. I've seen several lawn darts as a result of these motors. I had it in a D21 in my Big Daddy as well. Sorry man...that was one beautiful rocket!

 

[n3tjm]

Such a shame.... that is an awesome looking rocket. Was the E15 a pre-fire version, or was it a recently manufactured E15? Delays have a tendency to burn longer when they get older, since the end that is exposed to air (in the core) oxidizes, which makes the delay grain harder to ignite, which in turn makes it burn longer since it takes longer to start....

Do you have plans for that kit somewhere?

 

[rokitflite]

Yes, the motor was "pre-fire". I store all of them in my hallway closet in ammo boxes. I'm really annoyed because I bought about 20 of those engines for use in a radio controlled 4" dia Mach 10. Now I'll be damned if I'm going to risk that model with these engines! This is why I am dedicated to low power Estes motors, in 25 years of doing this I've only had 1 failure with an Estes motor (unfortunately that ONE was being filmed by a TV crew, but luckily didn't make it on the air!).
Sorry, there were no plans for that Scram Jet, I just added stuff as I went along. I will be building another one and I'll at least try to take pictures. That same day I lost an upscale BT-80 Goblin to an E11 reload when the micro-clips did not detach from the igniter which was held FIRMLY in place by the red nozzle cap. It got about 20 feet off the pad, almost yanked the launch controller out of my hand, where upon the rocket made a 90 degree turn and skipped along the ground down range. I'm sticking to "D" motors for now!

-Scott

 

[rbeckey]

rokitflite,
Sorry to hear of your loss. Those motors would be perfect for saucers. If you are not interested in saucers, let me know and perhaps we can arrange something.

 

[rokitflite]

Hey Bob,
I have a couple of E15s here that I plugged the end of (emptied out the ejection charge and filled the hole) that I won't be using. Can you use 'em?

-Scott

 

[Neil]

Im sure we could find homes for some E15-16s . If you need someone to take them off your hands, come to a CMASS launch, Ill trade ya some motors with working delays for a few supah-long delays. I have a few models that are wicked light and could use a 16 second delay. Well, maybe not 16 seconds, but still...

I have some E15-4s that I am pretty sure are post-fire. I have tried to light both, but the ignitor just popped out. So if you want some 4 second delay E15s, and are willing to trade for 16 second delays, just come to the first CMASS launch of the season, I will most likely be there. PM me for more details I wouldent try anything other than a saucer on those motors.... How many do you have left?

 

[Ryan S.]

I dont understand how your micro clips stayed attatched to the ignitor. Actually how did the ignitor stay attatched to the motor while it was burning. Usually they fall out and the microclips stay attatched but not very strongly attatched

 

[n3tjm]

This happens all the time with the motors that have the red plugs. Heat from the motor causes the cap plug to shrink (this is why you shouldn't reuse cap plugs). If the motor is hesitant to ignite, the heat from the motor igniting causes the cap plug to grip the nozzle. And when the motor finally fires the motor melts the caplug in front of nozzle, and fires through it. The caplug around the nozzle stays in place, igniter and all. This happens to me all the time with D9 and E11 loads...

 

[Ryan S.]

interesting, I was thinking something like this might be going on but wasn't sure. I have had ignitors stay on rockets where the ignitors were held in place with elastic bands (like G40s) but the clips pulled off, I guess your clips must have been mighty strong

 

[Neil]

snicker snicker.... I once had a First Fire JR. hang on the back of a G64! Man that bugger was SCORCHED! It was all black, and half the insulation was MELTED OFF! I kinda had the ignitor wrapped around the aft closure to make sure it didnt fall out before ignition.... It did its job!

 

[LMazza]

Rokitflite, to some extent i feel your pain. Last season I flew my Estes Maxi Honest John on an F21-8, which was a little long but had worked a few months earlier. To make a long story short I was unpleasantly surprised with a bonus delay and had ejection about 5 feet above the ground with the parachute fully inflating. (Good thing I got rid of the stock cord. ) The rocket survived, but my trust of AT single use delays did not fair as well.

 

[rokitflite]

Hi Neil,
Thanks for the offer but I'm afraid you did not understand the situation... The E with the 16 second delay WAS an E15-4. For what ever reason I got the bonus 12 second edition! I am working on a third channel on my model that will eject the nose cone on MY command so I don't destroy the model!


"Life is like an Aerotech delay grain; ya never know what you might get."

 

[Neil]

Actually, I did get it... I think someone said the problem is the age of your motors.... Yours are pre-fire, mine are post-fire.