Found a stash of motors

[LW Bercini]

I'm in the process of moving stuff out of my storage units into the new house. I found an unmarked moving box among the stuff destined for the future workshop. When I opened that box, there was another small cardboard box inside. Inside that small box were 10 SU Aerotech motors, and 2 reloads all still in their original plastic bags. I have absolutely no clue whatsoever how they came into my possession.

So here is the question: These have been in a non-climate controlled storage unit since 2005. Are they totally trashed?

 

[GDJ]

I'm no expert, but what's the worst thing that can happen if you tried to use them? My gut instinct would say that the reloads are fine since they were still sealed in the bags. If the SU motors were still sealed up, then they would be alright, but if they were in the open loose.......50/50.

(anyone?.......anyone?)

 

[jd2cylman]

Send them to me. I'll beta test them and eliminate your risk
Then I'll post a detailed launch report.

Adrian (with tongue firmly in cheek)

 

[LW Bercini]

Send them to me. I'll beta test them and eliminate your risk
Then I'll post a detailed launch report.

Adrian (with tongue firmly in cheek)

Which do you want first, the H97J or the H128W?

(tongue in normal position, but one eyebrow raised a la Spock)

 

[jd2cylman]

Which do you want first, the H97J or the H128W?

(tongue in normal position, but one eyebrow raised a la Spock)

I'm a sucker for blackjack motors! Bring it on :horse:

Adrian (both feet raised a la lazy boy recliner!)

 

[rockets4kids]

The first thing you need to do is make sure they are still certified. If they are no longer certified, you will only be able to fly them at an experimental launch.

Assuming they are APCP, they should still be good and safe to fly *if* you get get them lit. You likely have some surface oxidization which could make ignition very difficult.

 

[LW Bercini]

Sure...as soon as I finish reading the "Fly Me" thread...

 

[jungmann1]

They should be fine, I have flown stuff that old that my distributor has had sitting in her trailer since '05. They can be hard to light, if you can find a small wire brush that fits up the nozzle to remove the oxidized surface, that will help a lot.

 

[RWmarlow]

I have learned that "removing the oxidation" I always called it "scuffing the grain" works well....flew some AT F14-9J SU and Some USR (which Ive never had a true failure with) G45-8FS 29mm SU motors using a "New Bright" R/C rechargeable battery...using copperheads and an MPC "Lunar Lectric" Launch Controller (with extended leads) The First F14 chuffed....but after "scuffing the grain" at igniter install no problem's......

RW (that's my motor in that rocket and that's what my boys are pushing) Marlow (Uh-oh DUCK here comes the RSO!)

 

[Pantherjon]

So here is the question: These have been in a non-climate controlled storage unit since 2005. Are they totally trashed?

They should be fine, PROVIDED the plastic bags are intact..It is APCP and is not prone to cracking from temperature changes like black powder motors..

 

[shreadvector]

Black Powder motors do not crack from temperature cycling.

The propellant and the cardboard casing have different coefficients of thermal expansion, so the mechanical bond formed when they are loaded gets compromised after heating and then cooling.

To crack them requires an immense mechanical shock, such as hitting with a hammer. Dropping them will not crack them.

They should be fine, PROVIDED the plastic bags are intact..It is APCP and is not prone to cracking from temperature changes like black powder motors..

 

[gkieley]

Black Powder motors do not crack from temperature cycling.

I'm not certain that answer is correct. I excerpted a question/answer from the NAR L2 exam and the corresponding answer.


C16) Which of the following is most likely to cause catastrophic failure of a black powder rocket motor?
A) Temperature cycling B) Electromagnetic fields C) Vibration D) High altitude
-----------------
The answer is “A“. Temperature cycling is the primary cause of black powder rocket motor catastrophic failure. Temperature cycling cause expansion and contraction of the black powder grain and motor casing causing delamination between the case and propellant grain and cracks within the grain. The delamination and cracks expose additional burning surface that increases combustion pressures. The result is a motor failure. Note that shock or vibration can also damage a black powder rocket motor, however thermal cycling is the most likely cause of failure. Refer to the May and June 1992 issue of American Spacemodeling magazine, page 10, the article “A Theoretical Analysis of Why Black Powder Model Rocket Motors Fail“.

 

[shreadvector]

It does not cause cracks within the grain.

That is an error. i did one of the many R&D reports on temperature cycling and included x-ray and "unpeel the motor" inspections (with full permission of Estes who donated the motors). Grains NEVER cracked. The casing to propellant interface was degraded and the interface between the nozzle and propellant could develop a crack, but that is NOT a crack in the propellant grain and it results in LOWER peak thrust or peak pressure. The only thing the crack between the nozzle and propellant can do related to a cato, is it can allow the flame front to reach the actual catastrophic defect (no bond between casing and propellant) much sooner than normal. i have lots of thrust curves in my R&D report that illustrate this flattened peak thrust.

SO, answer A is correct, but the bloated explanation has bogus information padded into it.

I'm not certain that answer is correct. I excerpted a question/answer from the NAR L2 exam and the corresponding answer.


C16) Which of the following is most likely to cause catastrophic failure of a black powder rocket motor?
A) Temperature cycling B) Electromagnetic fields C) Vibration D) High altitude
-----------------
The answer is “A“. Temperature cycling is the primary cause of black powder rocket motor catastrophic failure. Temperature cycling cause expansion and contraction of the black powder grain and motor casing causing delamination between the case and propellant grain and cracks within the grain. The delamination and cracks expose additional burning surface that increases combustion pressures. The result is a motor failure. Note that shock or vibration can also damage a black powder rocket motor, however thermal cycling is the most likely cause of failure. Refer to the May and June 1992 issue of American Spacemodeling magazine, page 10, the article “A Theoretical Analysis of Why Black Powder Model Rocket Motors Fail“.

 

[Pantherjon]

Black Powder motors do not crack from temperature cycling.

The propellant and the cardboard casing have different coefficients of thermal expansion, so the mechanical bond formed when they are loaded gets compromised after heating and then cooling.

To crack them requires an immense mechanical shock, such as hitting with a hammer. Dropping them will not crack them.

You are correct..I meant debonding from the casing

 

[New Ocean]

I'm no expert, but what's the worst thing that can happen if you tried to use them? My gut instinct would say that the reloads are fine since they were still sealed in the bags. If the SU motors were still sealed up, th

The worst that can happen is one or more CATOs or recovery failures that destroy $100+ worth of rocket, possibly more than the value of the motors.

So there is real risk here, but I bet they are fine. Fly them in some applewhite kits if you don't want to risk it. (Because they are inexpensive to replace and do not all require a recovery event.)

 

[Buckeye]

I am currently flying some circa 1997 AT reloads in 29mm and 38mm. Got 'em from a guy at work who stored them very well, and I am trying to do the same. No problems. Succesfully launched about a dozen of them. They come with a Crapperhead and thermalite for extra oomph, but I just use a modern igniter. The biggest problem is that these have the first and second generation delay assemblies, which really suck!