Wildman Mach 2 on AT L1000W DMS??

[user 35735]

Hello all! This is my first time on this forum. I just got my L2, and to celebrate I wanted to build a (relatively) inexpensive high performance kit. I was looking at building a Wildman Mach 2 to fly on an AT L1000W DMS to keep the cost down, but of the good motor retention/shock cord mounting techniques I’ve seen are for reloads only. It seems to me that I could get away with friction fitting the motor and using an extra bulkhead and length of coupler to mount the shock cord. I was thinking I could drill holes in the bulkhead and use the motor charge as a backup. Has anyone ever build one of these using any sort of DMS? Any thoughts/suggestions are greatly appreciated!!

 

[SecondRow]

I was thinking I could drill holes in the bulkhead and use the motor charge as a backup.

I’m pretty sure that the L1000 is plugged.

 

[Walter Longburn]

The L1000 has a 18 second adjustable delay but I am guessing 18 seconds is going to be to short for a flight like this.

 

[user 35735]

I’ve seen both plugged and 14-18 second delays, not sure if I’d be better off doing one or the other. Might depend on where my friends order from…

 

[SecondRow]

My bad. I’ve only seen the plugged version.

 

[crossfire]

I’ve seen both plugged and 14-18 second delays, not sure if I’d be better off doing one or the other. Might depend on where my friends order from…

If it was my build I would want plugged motor if you know coast time. If it ejects to early you will have a hard time finding any peices of it.

 

[cerving]

No way you're going to be anywhere near apogee with that 18 second delay, and AT delays tend to run short anyway. If you're doing single-deploy you might want to look into an Eggtimer Apogee... it will get your chute out at apogee and beep out your apogee afterwards. Assuming you can find the rocket... but that's another issue.

 

[user 35735]

Thanks for the advice, definitely going to get my hands on a plugged motor. I’d love to use a casing and an aero pack MD retainer but I can’t see myself flying on motors that size often enough to justify the cost. As for the shock cord mount idea, do you think that will work reasonably well?

 

[mbeels]

I think that if you're flying a plugged motor, friction fitting a SU motor makes good sense. Most of the time when a motor gets kicked out of a rocket it is when the ejection charge goes off.

Attaching to a bulkhead should work fine, even better is to have the bulkhead sealed (or a second bulkhead) so that your deployment charge doesn't try and kick your motor out of the rocket. So basically keep the motor isolated from any recovery charges.

If you want some extra piece of mind, in addition to friction fitting, you can put a wrap of aluminum tape around the outside of the thrust ring and rocket.

 

[Walter Longburn]

definitely going to get my hands on a plugged motor.

I suppose you understand that all DMS L1000's come with an 18 second adjustable delay? If you want it plugged you just leave the black powder out.

 

[SecondRow]

They do?
https://csrocketry.com/rocket-motor...1000w-p-white-lightning-dms-rocket-motor.html

 

[Walter Longburn]

They do?
https://csrocketry.com/rocket-motor...1000w-p-white-lightning-dms-rocket-motor.html

Look at the label... if you've ever got one that came plugged send me a picture.
Or anyone for that matter.

 

[SecondRow]

Ahhhh. Cheerfully withdrawn!

Although, I feel like I’ve seen one

 

[Walter Longburn]

The RMS version L1090 is plugged.

 

[SecondRow]

Well, now that I’ve completely derailed the thread, I’ll let OP get back to getting answers to his original request.

 

[DaHabes]

Confusing. The link is to an L1000W-P but the listing is for a DMS with an 18 second delay. AT needs to update their website. Thrustcurve has it listed with a different name....

https://www.thrustcurve.org/motors/AeroTech/HP-L1000W/

 

[Walter Longburn]

AT needs to update their website.

It's csrocketry

 

[WILDMANRS]

This rocket was designed for a military purpose with the L1000 as the propellant .
The 18 second delay was way to short , but they used it anyhow with varying results the first one worked perfectly, the next 15 not so much .
They were never really intended to survive the flight just an added bonus to get a couple back.
i should add that after they were done is when I decided to make a kit out of it and add recovery options .

 

[user 35735]

This rocket was designed for a military purpose with the L1000 as the propellant .
The 18 second delay was way to short , but they used it anyhow with varying results the first one worked perfectly, the next 15 not so much .
They were never really intended to survive the flight just an added bonus to get a couple back.

If the rocket is constructed reasonably well and I don’t use the black powder charge in the L1000W, do you think the rocket will be likely to survive the launch?

 

[3stoogesrocketry]

If the rocket is constructed reasonably well and I don’t use the black powder charge in the L1000W, do you think the rocket will be likely to survive the launch?

Untill it hits the ground....

 

[rfjustin]

If the rocket is constructed reasonably well and I don’t use the black powder charge in the L1000W, do you think the rocket will be likely to survive the launch?

Motor eject on this is a no-go. The Mach 2 as designed is more than capable of surviving the flight. Your construction and recovery skills will be put to the test though. 20K+ feet is not a trivial effort...

 

[WILDMANRS]

If the rocket is constructed reasonably well and I don’t use the black powder charge in the L1000W, do you think the rocket will be likely to survive the launch?

Sure

 

[Buckeye]

If you want some extra piece of mind, in addition to friction fitting, you can put a wrap of aluminum tape around the outside of the thrust ring and rocket.

This is actually the most important part of friction fitting and this wrap of aluminum tape will carry most of the load. Motors can easily pop out without this wrap, no matter how tight the masking tape jammed into the motor tube.

 

[Cameron Anderson]

Friction fit alone with no attachment to the motor is iffy...not because of any ejection charge kicking the motor out, but when your chute comes out it is going to whip the airframe and the inertia will sling that spent DMS case out and a lllooonnnnggg fall. First, use an altimeter to control recover. Then friction fit the motor BUT ALSO drill holes in the ejection charge well and tie some kevlar to it to secure it just in case the motor wants out of the airframe. It worked for me, I've seen it work for other people too (it's where I got the idea). The Mach 2 is super fun but it is small so you have to get creative with your set up. Tracking is a must. Mine went to 21,259' and ended up miles away.

 

[tim cubbedge]

Mine went to 21,259' and ended up miles away.

What motor?

 

[Cameron Anderson]

What motor?

L1000. The gold standard for fun in that airframe!
I've also flown on a K455 dual thrust to 21,163.
At BALLS this year I'm flying an L265 mellow with a boat tail closure; it sims between 22 and 23k.

 

[crossfire]

Friction fit alone with no attachment to the motor is iffy...not because of any ejection charge kicking the motor out, but when your chute comes out it is going to whip the airframe and the inertia will sling that spent DMS case out and a lllooonnnnggg fall. First, use an altimeter to control recover. Then friction fit the motor BUT ALSO drill holes in the ejection charge well and tie some kevlar to it to secure it just in case the motor wants out of the airframe. It worked for me, I've seen it work for other people too (it's where I got the idea). The Mach 2 is super fun but it is small so you have to get creative with your set up. Tracking is a must. Mine went to 21,259' and ended up miles away.

I have never lost a single use motor because of friction fitting the motor. That's 30 plus years of HPR.

 

[Cameron Anderson]

I have never lost a single use motor because of friction fitting the motor. That's 30 plus years of HPR.

I see it a lot, not every month, but just about.
When it's a DMS H from 1,000 still trailing smoke and I can see it, I'm not too mad, but when it's an L from 20k, I'm a little more concerned.

 

[tim cubbedge]

I have never lost a single use motor because of friction fitting the motor. That's 30 plus years of HPR.

You are lucky. I see it happen a lot too.

 

[3stoogesrocketry]

Wait , is this our first friction fit debate of 2021 ?1?!