Aerotech oldies

[bobtheshortstop]

I recently got a hold of some OLD AT motors. An F14J, G55-10W, G25-15W. I’ve got plans for all of them, just need to find time to fly. Can anyone tell me their experience with these motors? I’m pretty sure it’s a good idea to change out the BP ejection charges after all these years, but is there anything else anyone would advise when it comes to using these old motors?

 

[mrwalsh85]

G55 is a fun motor. I have flown several over the years. Still have a stash of them.

If you have any, use the Estes Sonic Igniters, the type designed for their 29mm motors. Worked great for me. I also used the OEM ejection charge.But YMMV.

 

[jimzcatz]

The BP should be fine, check it and stir it up with a screwdriver if its clumped. IIRC the F14 isn't vintage?

 

[heada]

I have a few G25-15W motors as well as some F14-PJ motors. As has been said, as long as the BP is there and not clumped up it should be fine. On my G25 motors, the paper disc came loose and all the BP was lost on all but 1 motor so I'll have to replace it.

The F14-PJ can be used as a normal plugged motor. I have a cluster rocket that is 4x 24mm + 1x 29mm that I've been using them in.

 

[tab28682]

Watch out for the delays in these old motors. Unreliable. Best to not use motor ejection if possible.

 

[bobtheshortstop]

Watch out for the delays in these old motors. Unreliable. Best to not use motor ejection if possible.

Yeah I was a little concerned about that too, especially on the F14J. I've flown some old Black Max motors with no issues, but never black jack. I wouldn't trust any old Redline delays though. Speaking of which, I do have a few of the old G71R reloads, I know they had issues with the delays, would an RDK solve this issue?

 

[jimzcatz]

Yes

 

[caveduck]

I'd recommend against using really old white lightning or blackjack motors unless they've been sealed in an airtight container because the propellants are hygroscopic and take on water. I saw an old WL motor chuff 12-15 times before finally taking off with really low thrust and total impulse; crashed the model. Personally I had the same experience with a ~15-20 year old blackjack. Most of the other propellants seem better. I'm not sure if you can bake them out to drive off the absorbed moisture.

 

[Sooner Boomer]

I'd recommend against using really old white lightning or blackjack motors unless they've been sealed in an airtight container because the propellants are hygroscopic and take on water. I saw an old WL motor chuff 12-15 times before finally taking off with really low thrust and total impulse; crashed the model. Personally I had the same experience with a ~15-20 year old blackjack. Most of the other propellants seem better. I'm not sure if you can bake them out to drive off the absorbed moisture.

Yeah, what Duck says! I had a rocket several years ago I launched on a G55. It chuffed several times on the pad before taking off. It got up to about 50 feet when it chuffed again. It layed over horizontal before finally lighting for good. It took off "avec tres grand vitesse" going in criuse missile mode. Fortunately, it was pointed away from everything! Never found the rocket.

 

[Kartman]

In my experience White Lightning motors are the most susceptible to aging effects. I’m not sure being sealed in the plastic bag is a guarantee the motor will not chuff. Either the plastic is not a barrier to moisture or there is some other process going on. I will not purchase or fly old White Lightning motors. Blue Thunder motors however age very well. Change out the delay on those and enjoy the flight. YMMV of course.
Tom

 

[ECayemberg]

Great motors! I've burned those a few times and still have an F14J in the stash yet. Just a few notes, for what they're worth!

G55-10W: Like Mike says; great motor. The best 24mm motors around for a LONG time, IMO!!! Enjoy!
G25-15W: Another solid motor; the reload version lives on in the 29/120 hardware....I just flew one last month. That delay is way too long for anything you'd put it in, however! Don't worry, pull the paper cap, dump the BP into a paper cup, grab a drill bit that fits the BP pass hole (IIRC, ~5/32" works), put it in the hole and mark the depth with masking tape or equivalent. Re-mark the drill bit 1/32" deeper per second you'd like to remove (example: you'd drill 5/32" to get a 10 second delay). Drill to the new depth, replace/augment BP, paper cap and tape as necessary.
F14-4J: Love this motor...in the right airframe! And you got the right delay (as short as possible). Back when these were readily available, we learned to use them in really light rockets...our go to was the Estes Maniac with a 29mm mount. Most Loc, Aerotech, PML, etc. "mid power" birds will be too heavy for this motor. Put the motor in something you'd put an Estes D12 in and you'll be fine. Love the slow, smoky burn!

As others have said, it's a good idea to remove the BP, make sure it is dry, not clumpy, and replace...augment with fresh BP if desired. The delay grains age as the propellant ages; my experience is that the APCP delay grains tend to burn a tad longer than prescribed after a 20+ year again process. Plan accordingly and it's not a problem.

Long live classic motors! Enjoy!

 

[tab28682]

The reminder that the old WL and BJ motors are hydgroscopic leads me to wonder if a long tour in a food dehydrator might help. These work well for drying out 3D printed filaments with similar issues. Not a lot of access to the inside of these SU motors, though. Might take a long time to dry them out through the small nozzle orfice.

I have a dozen or two older WL motors that I want to use in a larger RC RG without ejection charges, so the old delays are not an issue. Also might use some in a saucer or similar model.

 

[Sooner Boomer]

The reminder that the old WL and BJ motors are hydgroscopic leads me to wonder if a long tour in a food dehydrator might help. These work well for drying out 3D printed filaments with similar issues. Not a lot of access to the inside of these SU motors, though. Might take a long time to dry them out through the small nozzle orfice.

I have a dozen or two older WL motors that I want to use in a larger RC RG without ejection charges, so the old delays are not an issue. Also might use some in a saucer or similar model.

I hate to be pessimistic, but I fear the moisture has penetrated the grain. I've got a bag* of old 24mm reload grains. They had swelled to the point that the slot had closed up and they could no longer be inserted into the case. Heating/dessicating isn't going to fix that.

* I posted pictures on the Propulsion forum. I gave the bag of grains away to be used as lighters in big EX motors or I would post another pic of how all the grains had swelled.

 

[jimzcatz]

.

 

[jimzcatz]

I hate to be pessimistic, but I fear the moisture has penetrated the grain. I've got a bag* of old 24mm reload grains. They had swelled to the point that the slot had closed up and they could no longer be inserted into the case. Heating/dessicating isn't going to fix that.

* I posted pictures on the Propulsion forum. I gave the bag of grains away to be used as lighters in big EX motors or I would post another pic of how all the grains had swelled.

Of course YMMV, but i have used such grains without issue, just recut the slot and let it ride.

 

[Sooner Boomer]

Of course YMMV, but i have used such grains without issue, just recut the slot and let it ride.

I think it would make an excellent research project; testing "normal" grains vs humidity swollen to see if/how it affects ignition and thrust. I wonder if, or how hard it would be to "artificially age" the grains, force them to take on moisture. I've got the time, and I'm willing to put together a test stand, if Aerotech is willing to supply the grains.

 

[tab28682]

I hate to be pessimistic, but I fear the moisture has penetrated the grain. I've got a bag* of old 24mm reload grains. They had swelled to the point that the slot had closed up and they could no longer be inserted into the case. Heating/dessicating isn't going to fix that.

* I posted pictures on the Propulsion forum. I gave the bag of grains away to be used as lighters in big EX motors or I would post another pic of how all the grains had swelled.

I have seen and still own a number of older motors and reloads with swollen grains.

Given how well a food dehydrator removes absorbed moisture from PLA and other 3D printing filament, I am going to give it a try. Will report back.

 

[tsmith1315]

I am going to give it a try. Will report back.

Will you restore the original geometry?

 

[rcktnut]

Yeah I was a little concerned about that too, especially on the F14J. I've flown some old Black Max motors with no issues, but never black jack. I wouldn't trust any old Redline delays though. Speaking of which, I do have a few of the old G71R reloads, I know they had issues with the delays, would an RDK solve this issue?

I had some G71's also used them up after replacing the delays with these: Hobby Delay Kits for 29mm Motors : Sirius Rocketry Online Store, For the Serious Rocketeer!
I bought the HDK 16's for a 7second delay. All flights were perfect. Also HDK 14= 4 sec delay and HDK 17= 10 sec delay.

 

[tab28682]

Will you restore the original geometry?

Too soon to tell if it will work, or not. I highly doubt it will go back to the exact original geometry.

Another factor I thought of would be a possible loss of plasticizer in the drains from the drying process. I acquired a number of old AT RMS RC 32 and 24mm reloads that had been stored a long time. In this case, the propellant had shrunk a bit and made each end slightly concave, while the outer perimeter stayed firmly attached. They were harder than normal/less rubbery, so guessing loss of some plasticizer.

These old loads ignite ok, but are down a little in thrust.

 

[mrwalsh85]

I've also got a few AT H45's and I132's, oh and an old school SU K250... I am pretty sure the I132's are Aerotech, but only way to verify is to fly.

I can't wait to find time to get these rockets prepped and burn some old school propellant. I think the K250 will either go in a Wildman Mach2 or a Madcow Tomach 54mm. Whatever doesn't get the K250 is getting a Loki L1040R

 

[prfesser]

The swelling that occurs with WL propellant is a chemical change, not simple absorption of moisture. Likely one or more of the metal powders in the propellant has reacted with moisture to form the corresponding oxide or hydroxide. A dehydrator or desiccant isn't going to remove the oxide/hydroxide, though it may remove moisture in the propellant that hasn't yet reacted.

Best -- Terry

 

[tab28682]

The swelling that occurs with WL propellant is a chemical change, not simple absorption of moisture. Likely one or more of the metal powders in the propellant has reacted with moisture to form the corresponding oxide or hydroxide. A dehydrator or desiccant isn't going to remove the oxide/hydroxide, though it may remove moisture in the propellant that hasn't yet reacted.

Best -- Terry

An excellent point. I had forgotten about any possible change of state in the propellant chemicals.

Some of my old WL motors are slightly swollen, with the common white oxidation deposits on the grain. Others are slightly swollen, with no visible oxidation at at all.

Will still attempt the drying experiment, with expectations greatly reduced...

Motors will be weighted on a decent gram scale before and after the drying attempt.

 

[fyrwrxz]

Omg! An old school K250! THE go-to motor back in the day! I figure as lazy as I am and the pandemic shut down has elevated me to the enviable position of "guy with the most antique propellant" on TRF!
This may soon be supplanted by the title "Mr. Cato". Stay tuned.....

 

[dpower]

I highly recommend not flying old, highly oxidized WL motors - I've seen more than one chuff itself off the rod/rail, then get up to full pressure after it tips nearly horizontal. Use them as camp-fire starters.

 

[rharshberger]

Flew a G110T and G55W today, using electronic ejection, both lit fine and the woosh part went great.

 

[4regt4]

An excellent point. I had forgotten about any possible change of state in the propellant chemicals.

Some of my old WL motors are slightly swollen, with the common white oxidation deposits on the grain. Others are slightly swollen, with no visible oxidation at at all.

Will still attempt the drying experiment, with expectations greatly reduced...

Motors will be weighted on a decent gram scale before and after the drying attempt.

Reigniting an old thread.....

I think I shot myself in the foot. I bought some old 29/40-120 reloads thinking I was saving a bunch of money. But they are 20ish years old. Didn't realize that when I bought them, and even so, I didn't realize that they age worse than BP motors.

The white lightening propellant is swollen, the slot significantly narrower. Likely way too narrow to insert an igniter. The color of the grain doesn't show any whitish oxidation.

It was mentioned further up in an earlier post here about "recutting" the slot. But it may be difficult to remove the grain from the paper casing to do this. These are E16 and F40 motors.

Am I screwed, or is there a way to revitalize these? If usable, I know they will need new delay elements.

Thanks,
Hans.

 

[Sooner Boomer]

I wouldn't launch them in a rocket you care about. My last misadventure of this type was with an old G64 reoad. It took two igniters (first clue), then when it finally lit, it chuffed and danced on the pad before finally lifting off. It was a sad, slow, arcing flight. It core-sampled before the ejection charge went off.