Aerotech Single Use High Power Rocket Motors

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BigRiJoe

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Do the above mentioned motors have a "lip" that can be used as a motor block?
 
Older ones don't. (from, like 10-15 years ago)
New ones do. you can tell by looking at them, adn that they are a shiny case..
 
Flew a H219T-14A DMS this year. Reliable motor. Get a DMS delay tool if you need to adjust it. It’s a different tool than the RMS.
 
Hey do have a thrust ring built into them. I got my L2 earlier this year using a DMS motor.
 
Yeah the new ones usually have a 3D printed appearing ring on the end. It felt like plastic. You can check with a motor vendor that offers product pictures to confirm. Buyrocketmotors or Apogee have pictures. You can use a cheaper vendor if you want after confirming.

I friction fitted mine with masking tape for retention for L-1 attempt.

The advantage of a DMS is you aren’t risking an expensive casing to possibly lose if the flight goes not as planned. Plus there is nothing to assemble before flight except for putting the bp ejection charge or altering time delay.
 
Hey do have a thrust ring built into them. I got my L2 earlier this year using a DMS motor.

Okay, my turn for a daffy question: I just opened the J270 so I could get a mass and COM for the rocket with the motor loaded

The instructions that came with the motor show the igniter held in place with a red plastic cap fitted over a protruding nozzle, but nozzle on the 38mm DMS motors is inside the thrust ring, and there is no cap included with the motor. What am I missing? What is the preferred method for holding the igniter in place?
 
I may be wrong as it's been a while since I've seen one but I thought the red cap was for the ejection charge?? I have used a small piece of tape to hold the igniter, just on one side lightly stuck on. Have to with Loki's.
 
There was a red cap for ejection charge and a metal washer on the H219T. Don’t forget washer first! Nothing on nozzle end that I remember.
 
From my experience, some come with a yellow cap you need to slice a wedge out of (to allow chuff exhaust without ripping the igniter out) and wedge over the igniter exit from the nozzle, and others come with a small elastic band that wrapped around the nozzle and holds the igniter.
 
Yes. I've flown the 29mm DMS motors. These come with caps to the nozzle extension (the part that protrudes from the aft end of the casing). Packed with the 38mm DMS motors there is a red cap for the ejection charge. but nothing for the nozzle.

The instructions for the 38mm DMS motor are the same as those for the 29mm motor -- and show a cap over a protruding nozzle

https://www.aerotech-rocketry.com/u...2_29-54mm DMS Instructions 12-29-15 Small.pdf

2954mmDMSinstructions.png
The instructions give advice on what to do if there is no cap supplied, but are a silent on what to do if the motor doesn't have an "extension".

Here is what I am dealing with.
20180911_183149.png

So advice or guidance on how to tape in the igniter would be appreciated.
 
Yes. I've flown the 29mm DMS motors. These come with caps to the nozzle extension (the part that protrudes from the aft end of the casing). Packed with the 38mm DMS motors there is a red cap for the ejection charge. but nothing for the nozzle.

The instructions for the 38mm DMS motor are the same as those for the 29mm motor -- and show a cap over a protruding nozzle

https://www.aerotech-rocketry.com/uploads/76b1c22b-afa5-4281-895f-fd7507a06752_29-54mm DMS Instructions 12-29-15 Small.pdf

View attachment 361556
The instructions give advice on what to do if there is no cap supplied, but are a silent on what to do if the motor doesn't have an "extension".

Here is what I am dealing with.
View attachment 361557

So advice or guidance on how to tape in the igniter would be appreciated.
I had something similar... I think? I just used painters tape to tape over the nozzle. Didn’t totally seal it, but never had an issue. 2/2 while just taping to the end of the rocket wherever it would stick.
 

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I kinked the motor starter around a bolt on bottom of a 1010 rail after making sure the pyrogen was at top of top fuel grain for the 38mm dms. And the bolt kept the motor starter from falling out while rocket was vertical.
 
Tape it, anywhere, even if you wrap it along side of air frame. Not meant to seal seal nozzle, just need to hold igniter in place.
Here is one that I taped to rail:
IMG_4502 (2).JPG
 
I had something similar... I think? I just used painters tape to tape over the nozzle. Didn’t totally seal it, but never had an issue. 2/2 while just taping to the end of the rocket wherever it would stick.

I kinked the motor starter around a bolt on bottom of a 1010 rail after making sure the pyrogen was at top of top fuel grain for the 38mm dms. And the bolt kept the motor starter from falling out while rocket was vertical.

Tape it, anywhere, even if you wrap it along side of air frame. Not meant to seal seal nozzle, just need to hold igniter in place.
Here is one that I taped to rail:

Thanks. I was worried that I'd misunderstood something very badly.

Yeah, I get that the cap is just meant to keep the igniter from falling out. I wonder If could make a plug of high-density packing foam, with a slit to hold the igniter, and a through-hole for venting?

Edit: Multiquote is a vexing and uncooperative tool.
 
Can you use "Blu-Tack" to hold the ignitor from (for love of a better term) falling down ?
 
For all types of motors I just wrap the leads of the igniter a few times around the standoff of the launch rail. For large diameter long motors taping the igniter to a small dowel allows them to be placed in the proper location in the motor.
 
For all types of motors I just wrap the leads of the igniter a few times around the standoff of the launch rail. For large diameter long motors taping the igniter to a small dowel allows them to be placed in the proper location in the motor.

Where does the dowel go?
 
Okay, my turn for a daffy question: I just opened the J270 so I could get a mass and COM for the rocket with the motor loaded

The instructions that came with the motor show the igniter held in place with a red plastic cap fitted over a protruding nozzle, but nozzle on the 38mm DMS motors is inside the thrust ring, and there is no cap included with the motor. What am I missing? What is the preferred method for holding the igniter in place?

Yeah, the instructions are super generic. My J250 was the same way. I just used a piece of blue tape since the whole cap concept was a dud. As long as that igniter is AAALLLLLLLLL THE WAY into the motor. you should be fine holding it there with tape. Just cover the hole with a small square. It's gonna get blown away and fried anyway.
 
How about a foam ear plug in the nozzle? The ones that roll real thin and then slowly swell back up.

Plugging a nozzle can cause a CATO from overpressure. If you haven’t personally tried this tactic with your own rocket and a DMS I would not be recommending it. In your idea it should combust. If it doesn’t ot oh. You know that Murphy guy likes to wreck stuff. Try tape or a external kink to standoff bolt to hold the igniter to somewhere on the launch rail it’s proven. Maybe I worry about introducing a problem. The other methods are flight proven. Not trying to be mean. Knife a slot into it my opinion if anybody wants to try earplug. But hey maybe I over worry.
 
Plugging a nozzle can cause a CATO from overpressure. If you haven’t personally tried this tactic with your own rocket and a DMS I would not be recommending it. In your idea it should combust. If it doesn’t ot oh. You know that Murphy guy likes to wreck stuff. Try tape or a external kink to standoff bolt to hold the igniter to somewhere on the launch rail it’s proven. Maybe I worry about introducing a problem. The other methods are flight proven. Not trying to be mean. Knife a slot into it my opinion if anybody wants to try earplug. But hey maybe I over worry.

I know the difference between Finagle's Law and Murphy's Law, too. I was thinking of a loose friction fit, akin to a self-sizing Estes plug. I'm sure many tricks have been tried by others.

What I find funny is that I've wedge-cut the caps on AT 24mm motors routinely. And then threaded the igniter wire through the gap, rather than tucking it down one side. Ah well.
 
Igniter gets taped to 1/8” dowel & gets shoved up to top grain but this is normally used on 75mm motors & larger.

Exactly. A dowel is only necessary when it’s difficult to feed an igniter all the way to the top or when the weight of the igniter head cannot be supported by the wires, including upper stages where the igniter may be driven downward (relative to the motor) by inertia when the rocket accelerates upward.
 
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