AT single use ejection charge amount

[T-Rex]

I tried a search, and I tried Aerotech's page. I am looking for how much BP is in an AT F50-6T single use motor (old Estes Composite).
I built an upscale K-48 Bandit in BTH-70 and attempted to duplicate the ducted baffling system. I need to ground test to arrive at the required charge and to ensure it isn't going to blow the fincan off during ejection....

I have a couple of the old single use motors and was thinking to use one for the first flight (in case it blows the fin can off). I suppose I could use the 29/40-120 casing to test and arrive at a required charge, then dump and adjust the charge in the SU motor before flight.

 

[tfish]

The below was posted by @afedeev

• Most Aerotech 29mm and 38mm motors come with either ~1.5g or 2.0g of BP provided in a plastic vial to be poured into ejection well.
• Most AT 24mm motors come with half that, or ~0.75g of BP.
• Q-Jets have either 0.3g or 0.5g of BP, depending on time of manufacturing (early ones had more) and motor impulse (and/or something else).
• Estes 18mm A/B/C have ~0.6g of BP.
• Estes 24mm D has ~0.8g of BP.
• Estes 29mm E/F have ~ 1.0g of BP.

https://www.rocketryforum.com/threads/deployment-charge-pressure-volume-and-black-powder.164364/
https://www.google.com/search?q=Aer...zLjAuMZgBAKABAcABAQ&sclient=gws-wiz-serp#ip=1
@AeroTech

Tony

 

[lakeroadster]

The below was posted by @afedeev

• Most Aerotech 29mm and 38mm motors come with either ~1.5g or 2.0g of BP provided in a plastic vial to be poured into ejection well.
• Most AT 24mm motors come with half that, or ~0.75g of BP.
• Q-Jets have either 0.3g or 0.5g of BP, depending on time of manufacturing (early ones had more) and motor impulse (and/or something else).
• Estes 18mm A/B/C have ~0.6g of BP.
• Estes 24mm D has ~0.8g of BP.
• Estes 29mm E/F have ~ 1.0g of BP.

https://www.rocketryforum.com/threads/deployment-charge-pressure-volume-and-black-powder.164364/
https://www.google.com/search?q=Aer...zLjAuMZgBAKABAcABAQ&sclient=gws-wiz-serp#ip=1
@AeroTech

Tony

That's some great information, thanks for posting this... and thanks to afadeev

 

[T-Rex]

Thank you @tfish . I knew if I said something someone would know the answer or the right way to search for it. (I just used the forum search). I have seen it mentioned to search from Google, but never seem to remember.

And I realize that I mis-thought/spoke in my original post. I am going to have to use a 29/40-120 casing (or a 29/180 casing) to figure out how much charge I need (starting with .5gm), then go from there.

 

[Tractionengines]

These are my notes on Aerotech Volumes that have been confirmed with them. Also a note about different amounts in 18mm Q-Jets based on delay time, for C and D motors only. Mostly matches what was posted above.
_______________________________

Quest 18mm Q-Jets have 0.25 gram ejection charges. EXCEPT the C & D motors with 4 second delays, which have 0.50 gram ejection charges.

[ The -6 and -8 second delays have a smaller ejection charge to avoid damaging body tubes in the smaller rockets they are usually used in. The -4 second delays have a larger ejection charge because they are normally used in larger, heavier rockets. This applies to the Black Max & White Lightning Cs and Ds versions only. ]

Quest 24mm Q-Jets have 0.7 grams for all D22W and E26W motors.

Aerotech SU 24 & 29mm Motors have .7 grams.

Aerotech DMS motors ship with 1.4 grams in the ejection charge kit.

Aerotech RMS reload kit charges:
18mm. .4 grams
24mm. .5 grams
29mm
- 29/40-120 Hobbyline .7 grams
- 29mm RMS HP-Style. 1.4 grams
38mm 2.1 grams

[Edit: format 29mm RMS. Note, SU= Single Use.]

 

[T-Rex]

Thank you @Tractionengines .
I've copied all data (AT & Estes) to a text file for future reference.

This forum has been a serious help over the years, and I'm sure will continue to be. Y'all are awesome!

 

[gdjsky01]

Be careful with early Q-Jets

I used an early C12-4. It blew my BT-50 rocket in half. When I posted that, AT said "You should not have used a -4 in the BT-50 rocket." Like that has ANYTHING to do with what happen. Never ever have I seen Estes instructions say, "Don't use a XNN-D in a BT-50 rocket". AT had NO CLUE what rocket I launched or how draggy it was. It flew a on C6-3 just fine. And they never asked. Not privately or otherwise.

Why bring this up... simply a word to the wise if you have earlier Q-Jets not used yet. And because I will continue to rag on AT support for blaming me for using a -4 in a BT-50 rocket. Are you joking? They did not even TRY to ask the engine code. Nor take any responsibility for their overly aggressive charge.

I was told privately (which is hearsay, I know that) that AT figured out that early Qjets had too much BP and reduced the BP. Yet all I got from them was "I should not have used a -4 in the BT-50 rocket"... where was THAT in the instructions?


LOL!
Happy Holidays one and all!

 

[AeroTech]

The below was posted by @afedeev

• Most Aerotech 29mm and 38mm motors come with either ~1.5g or 2.0g of BP provided in a plastic vial to be poured into ejection well.
• Most AT 24mm motors come with half that, or ~0.75g of BP.
• Q-Jets have either 0.3g or 0.5g of BP, depending on time of manufacturing (early ones had more) and motor impulse (and/or something else).
• Estes 18mm A/B/C have ~0.6g of BP.
• Estes 24mm D has ~0.8g of BP.
• Estes 29mm E/F have ~ 1.0g of BP.

https://www.rocketryforum.com/threads/deployment-charge-pressure-volume-and-black-powder.164364/
https://www.google.com/search?q=Aer...zLjAuMZgBAKABAcABAQ&sclient=gws-wiz-serp#ip=1
@AeroTech

Tony

So are you saying that all 18mm Q-Jets have LESS BP than the equivalent brand E motors (the Q-Jets never used more than 0.5g)? Interesting...

 

[Tractionengines]

So are you saying that all 18mm Q-Jets have LESS BP than the equivalent brand E motors (the Q-Jets never used more than 0.5g)? Interesting...

I think it's a design difference.

In the E motors the charge is the full diameter of the motor, and is a compressed disk on top of the delay element. Therefore it burns slower, and you loose more pressure thru the nozzle.

In AT motors it's loose powder inside a charge well. Also, with a "touch hole" between main motor chamber and charge well.

This means the E motors build pressure slower inside the body tube. So they need more powder. The AT build pressure faster, and use less.

On the other hand this is just my "thoughts" on it with no data to back it up, so I may be full of $...t. YMMV

 

[AeroTech]

I think it's a design difference.

In the E motors the charge is the full diameter of the motor, and is a compressed disk on top of the delay element. Therefore it burns slower, and you loose more pressure thru the nozzle.

In AT motors it's loose powder inside a charge well. Also, with a "touch hole" between main motor chamber and charge well.

This means the E motors build pressure slower inside the body tube. So they need more powder. The AT build pressure faster, and use less.

On the other hand this is just my "thoughts" on it with no data to back it up, so I may be full of $...t. YMMV

Sounds like a good topic for NARCON or the R&D event at NARAM.

 

[Tractionengines]

Sounds like a good topic for NARCON or the R&D event at NARAM.

Wouldn't take too much. A couple of sizes of body tubes with selectable motor mounts, a couple of pressure transducers. (Speed of pressure rise, and fall, peak pressure, etc. Checked at 2 places [ near motor, and near nose cone shoulder] ) Also 2 "high speed" cameras to look at what the characteristics of both ends are. (Speed of nose cone exiting the tube, size of flame front, amount of burning particulates, velocity/volume of gas out tube/nozzle, etc.)

Sounds like fun.

 

[gdjsky01]

Be careful with early Q-Jets

I used an early C12-4. It blew my BT-50 rocket in half. When I posted that, AT said "You should not have used a -4 in the BT-50 rocket." Like that has ANYTHING to do with what happen. Never ever have I seen Estes instructions say, "Don't use a XNN-D in a BT-50 rocket". AT had NO CLUE what rocket I launched or how draggy it was. It flew a on C6-3 just fine. And they never asked. Not privately or otherwise.

Why bring this up... simply a word to the wise if you have earlier Q-Jets not used yet. And because I will continue to rag on AT support for blaming me for using a -4 in a BT-50 rocket. Are you joking? They did not even TRY to ask the engine code. Nor take any responsibility for their overly aggressive charge.

I was told privately (which is hearsay, I know that) that AT figured out that early Qjets had too much BP and reduced the BP. Yet all I got from them was "I should not have used a -4 in the BT-50 rocket"... where was THAT in the instructions?


LOL!
Happy Holidays one and all!

So Aerotech replied. Yes Aerotech SAD indeed. I tell the truth. And you duck and cover. Sad indeed.

 

[AeroTech]

You know, rude comments, especially to vendors, are not well-tolerated on this forum.

If you want a response, make a civil comment or ask a civil question.

 

[gdjsky01]

And as soon as I make a rude comment, you let me know. All I have done is tell the truth. All you have done is duck and cover. "You should not have used a -4 in the BT-50", is your response. If it had zippered, or stripped the chute, all well and good, I am to blame. But blowing the rocket in HALF? As if the delay should have ANYTHING to do with an overly aggressive ejection charge?

Address the issue. Stop making it about ME. You, AT, your product is the issue. The DELAY should have nothing to do with blowing a rocket in half. Period. Address the issue. Stop making it about me. Make it about your product. I make it about AT because I expect better from AT. And you deny anything was wrong.

 

[AeroTech]

There is no issue. The C12-4 hasn’t changed, and has the same ejection charge it had from the beginning. Short delay motors have an ejection charge sized for the type of rockets they are most often used in. No manufacturer is going to create motors of the same delay with different weight ejection charges to satisfy edge cases. In those situations, the charge weight can be adjusted by the flyer.

 

[gdjsky01]

In those cases, you should compensate the buyer. But alas... aerotech is not gonna admit to anything. Or do anything. Which is sad.

I want to be clear. A C12-4 blew a BT-50 rocket in half. Not stripped the chute. Not zippered it. Not separated the shock cord. No. It went off near apogee, just like an Estes C6-3 had. Or an Estes B6-2 had. And Aerotech's position is, "You should not have used a -4 delay in a BT-50 rocket." That is codified here on TRF.

Please think about the absurdity of that statement. Why would the DELAY CHOICE have anything to do with an ejection charge destroying a rocket near apogee?

I'd not harp on this but for their absurd response. I have long since moved on with the loss of the rocket. Even using many other Aerotech products successfully. But their official reps response is, IMO, somewhat absurd. But that is that. I am not being nasty (or if perceived so, I apologize). Just a little disappointed/incredulous and people should know.

Nonetheless I will not respond anymore. I get it that AT is not going to offer anything. Happy New Year All!