PDA

View Full Version : Motor Shelf Life


Rocket Doctor
06-19-2008, 08:55 AM
Has anyone done any research into the "shelf life" of motors. Not only BP but HPR motors as well. And, from all companies over the years.

1. Does age have any effect on their performance?

2. What are the chances of having a CATO with older motors?

3. Does the power level change due to age?

4. Do motors that are classified, such as a A8 have the same power level from vintage to present motors.

5. Has the design of the motors changed over the years, especially from the variety of producers?

6. Does the type of storage, climate etc have an impact on motors?

7. What is the best way to store motors?

8. Should vintage motors only be collected, rather than being used?

9. Have nozzle changes been made over the years, for the same type motor?

These are just a few questions regarding motrs during the past 50 years.

What's you take on this?

Shreadvector
06-19-2008, 09:21 AM
All responses are from my memory/experience and apply only to BP motors.
Has anyone done any research into the "shelf life" of motors. Not only BP but HPR motors as well. And, from all companies over the years.

1. Does age have any effect on their performance? Only if stores improperly. If they absorb huge amounts of humidity and are not allowed to dry out, the delay time gets loooong and the propellant burn time goes up while the thrust level simultaneously goes down.

2. What are the chances of having a CATO with older motors? The word is cato or Cato, not an acronym. Impossible to answer this question as it has to do with storage. Defects during manufacture would produce a cato when new or old at the same rate. Only storage affects them with age.

3. Does the power level change due to age? No.

4. Do motors that are classified, such as a A8 have the same power level from vintage to present motors. NAR power levels have been documented and there was only an English/Metric change long, long ago. Using current metric power levels, a specific manufacturers A8 motor will not change unless the design changed. See next answer.

5. Has the design of the motors changed over the years, especially from the variety of producers? Estes motors have changed. Casings have changed and black powder suppliers have changed. See answer to number 9 below.

6. Does the type of storage, climate etc have an impact on motors? Yes. See numerous R&D reports on temperature and humidity cycling. No time to hunt for links now, but one club had one printed in and online newsletter (NIRA?)

7. What is the best way to store motors? "In a cool dry place"

8. Should vintage motors only be collected, rather than being used? Substitute "Jessica Alba" for "vintage motors" and answer that for yourself. :D

9. Have nozzle changes been made over the years, for the same type motor? Yes. Estes most definitely had a big nozzle change in the 1970's. Quest obviously had a nozzle change when they switched from the MPC type USA made motors with the smooth curved nozzles to the German made motors with conical nozzles with a straight throat.

These are just a few questions regarding motrs during the past 50 years.

What's you take on this?

Mark II
06-19-2008, 09:29 AM
RD,

I don't know how much help the following will be. I had a couple of Pro38 reloads (one grain), both stamped with the warning to use within one year. They are both about 3 years old. I burned one of them last Fall with no problem at all. AP motors use a form a rubber as a binder, I believe, and I have heard that rubber continues to cure (at a slow rate) indefinitely. This might or might not cause an APCP propellant grain to shrink a little bit over some large interval of time; I don't know.

I store my BP motors in a sturdy plastic bin with a tight fitting lid and keep them in a place where they will not be disturbed and will not get exposed to extreme temperature cycling. I store each one of the small handful of AP reloads that I have unopened in their original plastic bags and keep them in a box in a similar quiet place.

The oldest motors that I have, Estes 13mm A booster motors (manufactured in the early '90's I think), have worked fine in recent firings.

As far as I know, hybrid motors can be stored indefinitely. :D :D

Mark \\.

Niteowl
06-19-2008, 12:24 PM
I'm not able to contribute data, but am interested in the information provided.

I picked up seven packs of A10-0T motors at a rummage sale a couple years ago in a box of rocket supplies for only $5. The date code is "8 X 12", aka December 8, 1993 if I read the code correctly. I believe the seller's husband had an hobby shop at one time so I'd like to believe they were stored under reasonable conditions. Seeing as how these are OOP, they're worth holding onto should I ever get around to building a mini two-stage. FWIW, I "tested" one before I commited to a return to the sport and it fired fine.

I also got a few Aerotech B6-4T 18/20 reload kits I have no idea what to do with. Is the "Aerotech Composite Propellent" AP with a rubber binder?

Mark II
06-19-2008, 03:44 PM
I also got a few Aerotech B6-4T 18/20 reload kits I have no idea what to do with. Is the "Aerotech Composite Propellent" AP with a rubber binder?
You have B6 rated reload kits for the RMS 18/20 case??? :eek: I didn't know Aerotech ever made those. :confused: (The propellant grain must be the size of a pencil eraser! :p )

Aerotech Composite Propellant is a form of ammonium perchlorate composite propellant (APCP, sometimes just called AP). I only mentioned the shrinkage of the binder in an APCP propellant grain as a hypothetical possibility; I have no idea if that phenomenon has ever actually been observed in any very old composite propellant motors.

Mark \\.

JRThro
06-19-2008, 05:05 PM
All responses are from my memory/experience and apply only to BP motors.

8. Should vintage motors only be collected, rather than being used? Substitute "Jessica Alba" for "vintage motors" and answer that for yourself.
I think I'll take that as a "no"!

Initiator001
06-19-2008, 05:48 PM
You have B6 rated reload kits for the RMS 18/20 case??? :eek: I didn't know Aerotech ever made those. :confused: (The propellant grain must be the size of a pencil eraser! :p )

Mark \\.


When the model rocket RMS systems were originally released, AeroTech produced B6, C4, C6 and C10 reloads for the RMS-18/20 casing. :)

Low sales volume resulted in these products being discontinued. :(

I still have a few... ;)


Bob

Green Dragon
06-19-2008, 05:52 PM
well, in my experience , composite motors will age real well.

I;ve flown 20 year old single use with no issues ( Composite Dynamics, Enerjet, Aerotech ) .

I have had relaod grains that swelled up and were unable to fit intot he case ( mostly white lightning 18 and 24mm ) , ? due to humidity ? or what ?

As for Jessica Alba.. well... send her along and I'll check how much she;s aged ( well, from what I can see :P )

~ AL

Mark II
06-19-2008, 06:29 PM
When the model rocket RMS systems were originally released, AeroTech produced B6, C4, C6 and C10 reloads for the RMS-18/20 casing. :)

Low sales volume resulted in these products being discontinued. :(

I still have a few... ;)


Bob
Wow, I never knew that. I thought that they just made D's and, for awhile, E's for that case.

So how old would those B6's be?

Mark \\.

Initiator001
06-19-2008, 06:44 PM
Wow, I never knew that. I thought that they just made D's and, for awhile, E's for that case.

So how old would those B6's be?

Mark \\.

Let's see...

I think I got them in 1992 so that makes these reloads 16 years old. :eek:

PITA to load and get to ignite. The nozzle throat is VERY small. We (AeroTech) couldn't make 'A' motor reloads because the nozzle throat would be too small to fit a Copperhead igniter through.

Bob

shockwaveriderz
06-19-2008, 06:51 PM
When the model rocket RMS systems were originally released, AeroTech produced B6, C4, C6 and C10 reloads for the RMS-18/20 casing. :)

Low sales volume resulted in these products being discontinued. :(

I still have a few... ;)


Bob

me too!

terry dean

Royatl
06-20-2008, 02:01 AM
You have B6 rated reload kits for the RMS 18/20 case??? :eek: I didn't know Aerotech ever made those. :confused: (The propellant grain must be the size of a pencil eraser! :p )

Aerotech Composite Propellant is a form of ammonium perchlorate composite propellant (APCP, sometimes just called AP). I only mentioned the shrinkage of the binder in an APCP propellant grain as a hypothetical possibility; I have no idea if that phenomenon has ever actually been observed in any very old composite propellant motors.

Mark \\.


Shrinkage, i'm not sure about, but I'm pretty sure that certain formulations get more solid.

I have a few Composite Dynamics ProJet motors (Gary Rosenfield's company before Aerotech) made in 1980. A probe of the motors shows them to be much more solid than they were back in the day. The formulation of the propellant, though, is very different from the Aerotech formulations of today, as these are no-smoke no-flame motors.

White Lightning grains from 17-18 years ago are still rubbery and in fact have expanded due to other hygroscopic compounds in the propellant.

Green Dragon
06-20-2008, 05:33 PM
Shrinkage, i'm not sure about, but I'm pretty sure that certain formulations get more solid.

I have a few Composite Dynamics ProJet motors (Gary Rosenfield's company before Aerotech) made in 1980. A probe of the motors shows them to be much more solid than they were back in the day. The formulation of the propellant, though, is very different from the Aerotech formulations of today, as these are no-smoke no-flame motors.

White Lightning grains from 17-18 years ago are still rubbery and in fact have expanded due to other hygroscopic compounds in the propellant.

CD (Pro Jet ) motors used HTPB in the propellant, same as current AT propellant, so thinking they should age similar.

As for the White Lightning, you are very correct - have had old reloads swell so as to not be usable, won;t fit in the casings ( or the c-slots closed up ), particular problem on small loads, such as the B-C reloads mentioned, had to toss a whole bunch of those ( since they were multi-paks, then they were not sealed once the first one burned, so moisture got to them :(

~ AL

Gus
06-21-2008, 07:59 AM
I was just able to buy a bunch of the discontinued Apogee 10.5mm motors. :D

B2-5, A2-3, 1/2A2-2, 1/2A2-4, 1/2A2-6, 1/4 A2-4, 1/4 A2-6.

I have no idea if they are still good but I was able to acquire enough that I can launch some and still have enough for the collection. I know a number of the B altitude records were set with the B2s so I'm really excited about flying a couple.

Who made these for Apogee and why were they discontinued?

Royatl
06-21-2008, 10:02 AM
I was just able to buy a bunch of the discontinued Apogee 10.5mm motors. :D

B2-5, A2-3, 1/2A2-2, 1/2A2-4, 1/2A2-6, 1/4 A2-4, 1/4 A2-6.

Who made these for Apogee and why were they discontinued?


They were made the good ol'fashioned way, by hand, probably with an arbor press, by Tim.

My *second (maybe third) hand* information says that it was a number of reasons, from regulation, to insurance costs, to taking too much time.

Ltvscout
06-21-2008, 10:13 AM
I was just able to buy a bunch of the discontinued Apogee 10.5mm motors. :D

B2-5, A2-3, 1/2A2-2, 1/2A2-4, 1/2A2-6, 1/4 A2-4, 1/4 A2-6.

I have no idea if they are still good but I was able to acquire enough that I can launch some and still have enough for the collection. I know a number of the B altitude records were set with the B2s so I'm really excited about flying a couple.

Who made these for Apogee and why were they discontinued?
Cool! I foolishly sold mine about 6 or 7 years ago. Tim made those motors by hand.

They sure were a pain to light. Chad Ring taught me to use the old MRC igniters that had a glass bead. That usually always worked. Use a part of a toothpick as a motor plug. Don't press it in to firmly though. ;)

Green Dragon
06-21-2008, 03:30 PM
Cool! I foolishly sold mine about 6 or 7 years ago. Tim made those motors by hand.

They sure were a pain to light. Chad Ring taught me to use the old MRC igniters that had a glass bead. That usually always worked. Use a part of a toothpick as a motor plug. Don't press it in to firmly though. ;)

Yeah, wish I had some of those left myself.

Was saving a pair of B2's 9 B2-0 and B2-9 to try a centrix 2 stage again ( first try at a NyPower launch catoed, nto sure which Nypower that was, but it;s on the rocketman video . :(

not sure where that pair of motors went to over the years, should find em and try to fly.

( and yep, we always sued the MRC glass bead igniters, too.. nto sure who first tried tat, or if we all reinvented the wheeel ? )

~ AL

( finally back online, again.. sigh ... did I mention I hate computers ? )

Gus
06-21-2008, 05:05 PM
Guys,

Thanks for the tip about the MRC igniters. I actually know of a source for those.

I'm amazed that Tim hand pressed these himself and that he could maintain enough quality control to produce motors consistent enough to pass NAR S&T. I know he stopped producing them in about 2001.

I've gone back and read the Motor Matters thread about these motors. Very intersting stuff.

I'm looking forward to seeing them fly.

Ltvscout
06-21-2008, 07:14 PM
Guys,

Thanks for the tip about the MRC igniters. I actually know of a source for those.
Supposedly Bill based the new Quest igniters on the old MRC igniters. You may want to try those as well if they're easier to get. I'd buy up those MRC igniters if you know of a source. ;)