Propellant/ejection charge material still left after a launch

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byoungblood

byoungblood

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Hi all,

I'm another "BAR". I launched (and lost) a number of rockets from when I was about 10 till my mid-teens, and then built/started building a few other models over the intervening years, but never got around to launching anything.

I'm 36 now, and my son, who is just turning 3, is really interested in rockets, so I've taken him out a couple of times now to launch some of my old models. Its been good for me too because it has gotten me back into a hobby that isn't too expensive (I'm an on/off pilot, mostly off lately) and has a certain amount of immediate gratification that works well with my work schedule.

Anyway, I launched my rebuilt Estes Bullpup AGM-12D today with a B4-4 and a C6-5 today, and it flew well on both engines. When I got home and pulled the C motor out, I noticed that about half of the clay cap was still left in the motor. Looking further into it, I noticed that a good deal of the propellant and ejection charge material is still left in the motor. I've launched all manner of Estes motors A-D, and have never had this happen before. As I mentioned, the rocket seemed to have flown normally, and I had a good deployment of the streamer. Is this just something that happens every so often, or would Estes be interested in taking a look at it? I just bought them yesterday.

Bart
 
byoungblood said:
Hi all,

I'm another "BAR". I launched (and lost) a number of rockets from when I was about 10 till my mid-teens, and then built/started building a few other models over the intervening years, but never got around to launching anything.

I'm 36 now, and my son, who is just turning 3, is really interested in rockets, so I've taken him out a couple of times now to launch some of my old models. Its been good for me too because it has gotten me back into a hobby that isn't too expensive (I'm an on/off pilot, mostly off lately) and has a certain amount of immediate gratification that works well with my work schedule.

Anyway, I launched my rebuilt Estes Bullpup AGM-12D today with a B4-4 and a C6-5 today, and it flew well on both engines. When I got home and pulled the C motor out, I noticed that about half of the clay cap was still left in the motor. Looking further into it, I noticed that a good deal of the propellant and ejection charge material is still left in the motor. I've launched all manner of Estes motors A-D, and have never had this happen before. As I mentioned, the rocket seemed to have flown normally, and I had a good deployment of the streamer. Is this just something that happens every so often, or would Estes be interested in taking a look at it? I just bought them yesterday.

Bart
Click to expand...

Welcome back Bart. Sounds like you're getting your son started off right. Don't forget about Mom, she might get the bug as well ! As you said, the flights went well so I don't think you have anything unusual there unless you have unburnt material. Were the motors purchased recently ? Sorry just reread your last sentence. Subject to temperature variations ? (it would have to be a wide range to have an effect, like going from a garage in summer to the refrigerator, to affect the nozzle or ejection charge cap) If you're concerned posting a picture here might help.
 
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The only thing I could see here, and I'm no expert, would be a concern that you didn't get to the full altitude potential of the motor. If it deployed your recovery device (streamer), then the ejection charge did its job. So, do you think it achieved the expected altitude? If not, then for some reason the propellant didn't finish burning. If it did, then assume everything is okay, unless someone came along with a better answer.

If it did not achieve a near-expected altitude, you may need to send Estes the pictures and/or the spent casing for a refund. Or, knowing their customer support reputation, they'll probably just send you a new pack of motors over the phone.
 
Its a fairly common occurrence... The claycap doesn't always blow out entirely. What youre seeing inside the case is burned propellant and liner ash... Not unburned propellant.... Motor cases are usually partly full of junk after being fired.... Later! OL JR
 
OK, because it is large gobs of material, not the normal charring and small traces of unburned/partially burned powder that I'm used to. I'll try to take a picture of the inside if I can get enough lighting in there.

Altitude wise its hard to say because it weathercocked on me a little so it arced enough that I had a hard time tracking it against the overcast until the ejection charge went off. I'm glad I used the streamer on that last launch because who knows where it would have ended up with a 'chute.
 
Hmm... How windy was it ? What was the B4 flight like ? How much does the rocket weigh ? I would have guessed more weathervaning with the B4 than the C6 but what did you see ?
 
luke strawwalker said:
Its a fairly common occurrence... The claycap doesn't always blow out entirely. What youre seeing inside the case is burned propellant and liner ash... Not unburned propellant.... Motor cases are usually partly full of junk after being fired.... Later! OL JR
Click to expand...


++1

Trust me and ol JR, you have no unburned propellant. I have taken apart Estes motors, the propellant is one VERY hard slug of BP. Once lit, it will not go out. What you have is residue. Instead of trying to take pics, unwrap the cardboard case so you can really see what you have,
 
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luke strawwalker said:
Its a fairly common occurrence... The claycap doesn't always blow out entirely. What youre seeing inside the case is burned propellant and liner ash... Not unburned propellant.... Motor cases are usually partly full of junk after being fired.... Later! OL JR
Click to expand...

+2
Ol JR is exactly correct, this is a common occurence. Your seeing propellant and liner/casing ash.
 
Here are the pictures. There's not even a clear line of sight down to the nozzle if you shine a flashlight through there.

image.jpgimage.jpgimage.jpg
 
samb said:
Hmm... How windy was it ? What was the B4 flight like ? How much does the rocket weigh ? I would have guessed more weathervaning with the B4 than the C6 but what did you see ?
Click to expand...

The wind shifted direction on me while i was launching it on the C6 and there were a couple of decent gusts. The B4 flight was actually pretty straight and I recovered the rocket maybe 60' or so using a chute. I switched to the streamer since there was some wind and I didn't want to risk losing the rocket on the larger motor.

It is a more or less stock Estes Bullpup that I built when I was 11 or 12. Fins had just popped off of it from being moved around for 20 years and the paint was a bit worn so I decided to give it an overhaul.
 
byoungblood said:
Here are the pictures. There's not even a clear line of sight down to the nozzle if you shine a flashlight through there.

View attachment 179632View attachment 179633View attachment 179635
Click to expand...

Based upon this, I'd say it's normal after-burn residue, assuming the motor's performance was nominal.

Estes motors are pretty much a single grain of BP. It'd be difficult--if not impossible-- to have unburned propellant with that design. If anything goes wrong with an Estes motor, it's that the BP grain gets small cracks. This causes more burning surface area, leading to over-pressurization and destruction of the motor--usually along with the rocket. Even then you typically don't see unburned propellant. Their longer, larger-diameter motors are much more susceptible to this--it'll happen on their 24mm E's with frequency enough where the largest BP I'll ever fly is a 24mmx70mm (C11, D12).

But anyways, byoungblood, that C6 is fine.


Later!

--Coop
 
I'll just add to the concensus that the used C6 looks about right. My concern was that you said the C6 flight weathercocked and a flight with a motor with less peak thrust (the B4) flew straight. But it sounds like the wind picked up or a gust hit the C6 flight right off the rod to send it a little sideways. Time for you and your son to go out and burn the rest of those motors !
 
Thanks guys. I'd just never seen that before.

I'll post up some pictures of some of the rockets I've been working on the past couple of weeks.
 
Just adding that you will see some variation here -- some spent motors will end up appearing somewhat "cleaner" than others, especially motors from different packs bought some months apart. But as everyone else has said, what you have there is typical. I do know what you mean though. The motors I used back in the 1960s and even those I bought ten years ago had less ash residue in them after they were fired. I have wondered whether it may have had something to do with the type and quality of the wood used today to make the charcoal component of black powder.
 

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