Is this another Estes failure?

[Salvage-1]

Flew a BT-80 rocket on Saturday. 3 x D12-5 Lift off was perfect then, right at the moment of burnout an ejection charge went off and blew the nose off. Remainder of the flight was not quite as pretty.

One of these motors is not like the others, One of these things just doesn't belong. After the flight I checked and two of the motors looks just as they should, I believe that their charge went off as scheduled, although I didnt notice at the time. One looks like it doesnt belong.

To me it looks like there was a burn down the side of the tube. Other thoughts pls? Do I inform NAR and Estes?

 

[kjohnson]

No clue, your description is terrible.

What made the flight not so pretty? Was it just that the 3rd motor didn't completely blow it's ejection cap? Did one of the motors not light at liftoff and then burn after he other two ejected, but from the top down?

kj

 

[[POW]Eagle159]

It is actually common to have the ejection clay cap not always blow off completely... I have had that happen to me many times,(5+) with perfect sucessful flights.

 

[Salvage-1]

All three motors lit together. Boost looked exactly the same as I have had before, but just after (less than 1/2 second) the motors stopped the thrust phase, the nose cone ejected, with force, and with a burst of smoke, the main rocket then went unstable and spun around for a second or two before starting to flutter down.
One of the other people at the launch has told me that he did see the normal ejection charge going off whilst the rocket was unstable, but there was smoke coming out of the top of the rocket for a good two seconds immediately after ejection. There was also delay grain smoke coming from the aft of the rocket. So, I am guessing from the looks of the other two, and that description that 2 of the 3 motors worked fine, and one had the ejection charge go off very early, or something else happened that pressurised the rocket enough to blow the nose off.
These were 3 motors from the same pack. Both of the others have no clay left and look like they went through a normal burn. The one pictured is the 'duff one'.

Edit--
The body tube has 'pressure release' pinholes around it, just in case some of the motors fire their ejection very close together. I have had this happen before and the nose shot off like a cannonball, snapping original elastic 'shock cord'. After that flight, I put a few holes in the BT to bleed off any overly strong pressure. Also so I can use my Altimeter Two in there. This also means that I dont think that the early nose separation could be anything except an ejection charge going off.

Confused and confounded.

 

[Bazookadale]

So one very short delay - notify Estes and fill out a MESS report with the NAR

 

[Verna]

To me it looks like there was a burn down the side of the tube. Other thoughts pls? Do I inform NAR and Estes?

View attachment 99264View attachment 99265

I've seen many D engines look like this with no damage but 3 D engines in a small tube is a lot of ejection so venting some gas is a good idea. Is it possible you accidentally put a D booster in with two that had ejections? What you describe sounnds like burn through to me which would have the time frame you describe.

Verna
www.vernarockets.com

 

[Salvage-1]

I've seen many D engines look like this with no damage but 3 D engines in a small tube is a lot of ejection so venting some gas is a good idea. Is it possible you accidentally put a D booster in with two that had ejections? What you describe sounnds like burn through to me which would have the time frame you describe.

Verna
www.vernarockets.com

Nope, these were purchased from the onsite vendor, and installed 2 mins before the flight. Emptied the 3 pack into the rocket.

I HAVE in the past used c6-0 x2 and a c6-5 in one of my BT-60 rockets, but, I learned through experience that this doesnt work unless you seal the ends of the booster motors. I wasnt going to make that mistake with D's or E's Made a joke when this happened that it looked like when it happened on that my other c6 rocket.

I am going to fill out a MESS report and tell Estes, just in case this was an engine problem. Other than that, I am chalking it off as 'stuff happens once in a while'.

 

[Micromeister]

Flew a BT-80 rocket on Saturday. 3 x D12-5 Lift off was perfect then, right at the moment of burnout an ejection charge went off and blew the nose off. Remainder of the flight was not quite as pretty.

One of these motors is not like the others, One of these things just doesn't belong. After the flight I checked and two of the motors looks just as they should, I believe that their charge went off as scheduled, although I didnt notice at the time. One looks like it doesnt belong.

To me it looks like there was a burn down the side of the tube. Other thoughts pls? Do I inform NAR and Estes?

View attachment 99264View attachment 99265

Salvage:
Been flying D clusted models since the D was introduces as D13's back in the day. Thousands of 2-5motor D12 clusted BT-60,70 and 80 models, several thousand spent D12 motors. Over the last 4 decades I've seen many clay caps as in your photos without a single deployment problem. Over Pressure is hardly a problem with BP motors particularly in BT-80 or larger models. I generally use a Bt-50 or BT-60 Stuffer tube most of the body length just to INCREASE the ejection pressure leaving about 12" forward as the chute compartment for 30-48" nylon chutes.
Don't understand why you think you had a problem? You could have had a short delay train on one motor. Or one of any number of NORMAL variences with the group of motors manufacturing 10% tolerances.
With the Number of varing factors involved in cluster ignition & motor burn rates it is all but impossible for more then one motor to eject at the same time. Occasionally you'll get two very close together POP-POP, but I've never had more then two that close.
Igniters do not heat or burn at exactly the same instant, Motors do not start at exactly the same split second, burn rates within each motor vary, Delay train burns vary as do the ejection charges. This is one of the reasons it is most important to design our Clusterd models around getting the laundry out with the pressure from a single ejection.

Did you Weigh you motors before installing them? Its a quick & easy way to get a general idea of how closely matched motors are to others for the same pack or not.

Did you count the pop, pop pop's at ejection? that's how most BP cluster folks get an early reading on if all motors in the cluster fired.

You can fill out a mess report of you want and e-mail Estes but from your discription and photos it seems you didn't have anything other then normal D12 motor operations.
Hope this helps.

 

[Salvage-1]

The problem was that one of the three seemed to have no delay, where the others both had the 5 seconds. With two of the motors having all the clay blown out, and one not, I jumped to the conclusion that the faulty one was the one with clay still in. Sounds like I may have no idea which one it was.

 

[Mojo_wire]

I had a similar issue yesterday -- two flights each of a Baby Bertha and Hornet. The first two with a B6-4 went perfectly, the I put a C6-5 in each.

The Bertha deployed the chute, but it didn't open and when I recovered the rocket the chute was a melted mess and the wadding hasn't moved. The Hornet seemed like a perfect flight but the wadding had only moved halfway up the tube, so it seemed like the ejection charge was really light and I got lucky to get the chute out. The Bertha clearly tumbled for a while before the chute came out, so i guess it stayed in the tube getting cooked and then the velocity of the fall pulled it free. Both engines looked like the OP's photo, with only about a quarter of the ejection cap displaced.

I'm pretty sure the engines came from the same package, so there must be some inconsistency within Estes' production but I'd guess that since both engines did have enough ejection force to get the nose cone off and the chute out, that wouldn't be termed a failure.

Frustrating to lose a chute and to have risked two bad landings, but I guess it's part of the risk of flying.

 

[Grimracer]

Any chance this was drag seperation?
Grim