Estes ejection charges

[SecretSquirrel]

I know there have been discussions about the stronger ejection charges in Estes motors, but I've seen new issues lately.

I first noticed this at the NSL. I bought all new motors to take to that event and the hobby shop I bought them at had recently restocked.

The first problem showed up in my Red Baron. The ejection charge left more than usual residue in the body tube making the glider nose heavy. So everyone got to see me lawndart one of my more popular kits. This was in the A8-3 engine.

The second issue showed up in B6-4 and C6-5 engines. All the rockets I flew on these motors have blistered paint just above the engine mount. All the rockets were painted with Krylon. I had not seen this before on any of my flights. This did not happen on A8-5, C11-5 or D12-5 motors.

has anyone else noticed anything like this? Hopefully this is a fluke.

 

[Fore Check]

I suffered a separation due to a burnt-through shock cord at NSL. The shock cord was 1/8" flat elastic. First flight, so no previous damage. The shock cord was anchored to the motor mount via kevlar (BT50 based rocket) I used 8 sheets of recovery wadding, and then set the cord in on top of the wadding with parachute last (this is how I always do it.) I used a brand new C6-5.

That's the first time that's *ever* happened to me before.


I've had a "blistering" problem on a BT60 based rocket, flying on a D12-5 recently. Blistered in the same location that you're describing.





Was your blistering on a minimum diameter rocket (like the Spirit of Texas?) Just curious.

 

[shockwaveriderz]

sounds to me like a "hot" batch of engines.....what are the date codes....sometimes estes engines will have higher than normal "energetic" ejection charges.....they make engines in a batch mode...so maybe its just a hot batch.....


It happens off and on.....

 

[SecretSquirrel]

Originally posted by Fore Check

Was your blistering on a minimum diameter rocket (like the Spirit of Texas?) Just curious.

The blistering happened on BT20, 50 and 55 based rockets.

 

[Micromeister]

Blistering seems to be a periodic happening, I've had this happen on models off and on for years. I've also found these type anomalies seem to appear in direct proportion to the number of spectators at the launch. Humm something to do with that guy named Murphy Ya never blister a model flying for fun but just try to get that miinimum diameter Scale model not to blister during a contest flight Shockie may be correct, sounds like a HOT batch of motors.. Would you post the date codes please?
Thanks

 

[rabidsheeep]

i launched my alpha awhile ago on a quest c6-7 and had no residue... then i launched it on a b (something or the other) and the chute was melted, and the shock cord damaged...

i also had the privlidge (sp) of having some red thing shoot out of the back of a rocket after it got caught up on the rod, looped a foot and a half up, and hit the ground... i think it was the ejection charge, but the thing flew a good 10 feet...

 

[Gus]

I'm quite concerned with several odd engine occurences during launches this month.

Last week I lost a scatch built, on an Estes D12-3, that caught fire just above the motor mount, and burned through the body tube. Parachute was attached with Kevlar was blown clear out of the rocket. Just above the motor mount the body tube burned completely through all the way around. No evidence of an explosion, and no flames were seen during flight. Looks like a large amount of hot particles started the tube burning all the way around. Rocket had been launched before, on the same type engine, with no problems. I've never seen this before.

Today, another scratchbuilt was still smoldering at the engine block after touchdown. Because of last week's occurence I immediately pulled the engine out and found way more residue in the tube (a BT55,completely black) than ever before. Engine again was a D12-3 but from a different pack.

Another rocket today, launched without problems a number of times before on C6-5s, went straight up about 50 feet, then started cartwheeling, then tumbled to the ground, then ejected. I inspected the engine moments later and the nozzle appeared normal. I don't have any good explanation why this rocket went unstable. Nothing different about the rocket either before or after launch.

I've been using Estes engines for 30+ years. Although I've occasionally had a bad engine, I've never seen a string of occurences like this in such a short period of time. And I've never had a body tube burn completely through all the way around.

All the engines were newly purchased so I'm left wondering if there's a quality problem. Frankly, i'm afraid to use any of the D12-3s I have left and am going to buy new from a different shop.

 

[GuyNoir]

Originally posted by SecretSquirrel
I know there have been discussions about the stronger ejection charges in Estes motors, but I've seen new issues lately.

. . .

has anyone else noticed anything like this? Hopefully this is a fluke.

Anyone experiencing difficulties with engines should take a few minutes to report those problems at:

https://nar.org/NARmessform.html

Please be sure, if possible, to retain the motor casing so you can obtain the date or motor code. This helps the NAR's Standards and Testing committee in attempting to analyse the problems.

 

[shreadvector]

Blistering above the motor is usually *NOT* from the ejection charge. (I said "usually"). It is usually from the delay 'afterburn'. This is very bad in special composite motors like the Apogee medalist motors, but it also occurs in Black Powder motors. There is some delay train still burning after the ejection charge goes off and it produces a large "road flare" flame effect. Actually it's not an effect - it's a FLAME.

perhaps they added something to the delay that makes it burn hotter? Notice any more or less smoke than usual?

Powerful ejection charges are obvious and very different from the roasting effect. They go "BOOM" rather than "POP". I've seen this in Estes motors from 8 or 10 years ago (when did Apogee have the special run of Estes 1/4A3-2T motors made?). I also saw this in the last batch of USA made Quest A6-4 motors. They had more total Impulse in the ejection charge than in the motor. New German motors do not have this problem (but boy do they make lots of tracking smoke!).

Another report was on an unstable rocket. Why would a normally stable rocket fly unstable when using a motor that it flew stable with before?
Did you look at the nozzle? We have had several VERY scary "flights" where the rocket had little thrust and/or veered into cruise missile mode. After crashing and putting out the brush fire, we examine the nozzle and find that it is either too wide (wider than normal at the throat) or it is eroded asymmetrically. The asymmetric erosion is bad and you can clearly see the exhaust residue all over the missing area of the nozzle indicating that it disappeared at ignition or shortly thereafter.

All unstable flights with Estes motors from years "A" and "B" and maybe "C" need to be inspected and if the motor/nozzle is the cause, a M.E.S.S. form filled out and the manufacturer notified. The least that will happen is a package of replacement motors and a kit. The most that will happen is an improvement in materials used in manufacturing and a product that performs like we remember for decades and decades.

I hope this info helps folks.

-Fred Shecter NAR 20117

 

[Gus]

Mark, Fred,

Thanks for your responses. I saved the motor from the burn-through so I'll send in the numbers.

But your response raises another unanswered question which I've seen come up in several previous threads.

I know NAR certifies "accurate total impulse and time delay" but is any information gathered, or are there any standards, for "ejection impulse"?

My impression is that an A, B, and C each put out a similar ejection impulse (volume/speed of gas) but that a D puts out much more. Are there standards motors are supposed to meet? Any numbers available on this?

Gus

(Attached photo is of burned through body tube and looking through transition into top of motor mount)

 

[powderburner]

With THAT much damage, you may have had a CATO partway through the motor burn. If the grain delaminated from the case and the combustion chamber vented forward, you would get a good dose of hot gasses.
Or, if it WAS the ejection charge from h**l, it looks like they still owe you a replacement?

 

[Gus]

Don,

Didn't mean to hijack this thread but it seems I had a similar problem differing only in magnitude and, because it just happened, I'm able to more fully document it.

Powderburner,

Attached are photos of the nozzle and forward ends of the motor. Doesn't really look like anything catastrophic happened to the motor itself. Date on motor was 5/20/02, though just recently purchased. Fred's suggestion of a road-flare like effect from delay afterburn seems the most reasonable suggestion.

I fly on a small field and occasionally lose a rocket. Although losing rockets for me is infrequent, the possibility of sending a parachute borne smolderer into the nearby houses worries me. Having two such incidents within the last two weeks is pretty concerning.

As for what Estes owes me, not a thing. I couldn't possibly repay them for all the fun they've provided me over all these years. If there's a manufacturing problem I just want them to be aware of it so we can all continue to have safe fun.

Gus

 

[wyldbill]

I've had a similar problem w/ an E9 in my Drake. It wasn't painted, but the BT itself is scorched and the glassine has bubbled and blistered, separating from the paper. The engine itseld looks similar to the one in Gus' post. I also saw similar light scorching in a Mean Machine, the glue on the rear ring was a toasty brown.

I agree that we may be seeing hot delays in the newer motors.