How much does direction of ejection charge matter?

How unsurprising.

Reply to
Jerry Irvine
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Agreed! Especially if your ejection charge is pushing the recovery system deeper into the tube, which will make it more likely to get wedged in.

If you have a design such that you have to go that route, consider longer leads on your charge and run it down past the recovery system, so that it sits underneath. You risk entanglement in the recovery system this way, although I've had better luck with that (no entanglements thus far) than hoping the nosecone pulls the recovery system out (I've had that fail twice, both times on the same rocket).

-Kevin

Reply to
Kevin Trojanowski

I wish I could of attended yeasterday, but I was on call and with a 30 min response time, coverdale is just a little to distant.

Gota one more for you:

RMR - JI, why did you send regulated rocket motors through US Postal on several occasions?

JI - TRA would not certify my motors -- stay on topic you moron...

Fred

Reply to
W. E. Fred Wallace

I thought you said ROL auctions were legal?

If not, we can call the postal inspectors together.

Reply to
Jerry Irvine

Note that the separation point doesn't have to be at the base of the nose cone, either -- it can be near the motor mount, as in a "zipperless" design, or even centered over the part of the tube where the parachute rests. Put the parachute near -- (Not "At") the middle of the harness, and put enough charge in there to kick the two pieces apart to the ends of the harness, and the 'chute will be left hanging in midair between them -- a very good place for it.

The reason you don't put the chute AT the midpoint is that the two pieces then swing around and clatter together both at the moment the chute opens, and at various times on the way down. Serious damage can result. I suggest having about 20' of harness on a typical L1/L2 rocket with the parachute about 8' from one end.

Pressure is pressure -- it doesn't matter where it's pointed, and it's a good idea to disperse it through a baffle.

Reply to
Pelysma

At least it's not constantly repeating the same old crap like you constantly do. And I think it's more entertaining than anything you post.

Reply to
Phil Stein

Maybe not if you had any idea of what I was talking about.

Reply to
Phil Stein

Maybe so, if I was talking about what I thought I was talking about.

Reply to
Jerry Irvine

Like THIS post by you for example?

You might TRY to post something about rockets.

I post about rocket methods, products, and, yes, regs and politics.

Right now regs and politics are in the forefront.

It makes sense to discuss those issues.

Although renaming the thread and then staying on topic might help.

Redirecting almost every thread to a "Jerry-rant" not only contributes nothing to any positive debate, it lowers the overall level of civility on rmr. That may constitute "entertainment" to you (and Fred, "Grave", Ray), but it is CLEARLY off-topic, rude, and anti-helpful.

Jerry

Reply to
Jerry Irvine

Yeah but you weren't.

Reply to
Phil Stein

I just can't resist piling on. I mean, golly, it's for his own pleasure!!

rmr - Jerry, why did you send high power rocket motors to a minor via common US mail?

JI - Just living the life style, man, living the life style!

Reply to
default

ROFL!!!!

Reply to
Phil Stein

See Phil, Jerry does think,"it's all about Jerry"

Reply to
WallaceF

As if there was ever any doubt. 8-)

Reply to
Phil Stein

I've never had a PML piston jam, but you have to keep the piston and the airframe tube really clean. With Quantum tube, you will find it tighter in cold weather and may have to sand the outside of the piston to loosen it up.

The typical dual deployment setup has very little airframe tubing left on the fin can and motor mount assembly. (look at the illustrations on the PML website) It effectively functions as a "plug" like the nose cone, just facing backwards. You end up with two sections of airframe tubing with the electronics in the middle, the fin can on the back end and the nose cone on the front end. The drogue will be blown out the back and the main out the front. PML sells a retrofit kit to convert to dual deployment. You would end up cutting off the airframe forward of the engine mount and installing a coupler/bulkplate.

If you wanted electronics, but not dual deployment, you could cut the airframe and insert an electronics bay just forward of the engine.

Larry

Reply to
Larry

Pretty clean is good enough.

THis is something you do once. Also, I've never seen a problem with any that are real loose.

I've sucessfully turned the coupler into an electronics bay.

Reply to
Phil Stein

It won't hurt to leave the piston in place with this configuration. Everything works the same as it does without the piston. I like the pistons for flights that use motor ejection.

Reply to
Phil Stein

Thank you all for your responses.

I built my Ariel per the instructions. I am going to launch it (for my L1 cert) on an H148R with a 10 second delay. According to wrasp it will be falling at just under 60 ft/sec when the charge fires. I was trying to figure out a way (without major mods) to use my electronics to fire at apogee and use the motor ejection as a backup. It appears I can't do it without major mods to the rocket. By major, I mean cutting up the airframe.

I was trying to think of a way where the electronics would be in the payload and I would put a charge in the top of the piston, pointing towards the motor. When it fired it would pressurize the tube behind the piston (the area between the piston and the motor). I don't know if that would work.

I like the CPR stuff but it costs more than I paid for my rocket to begin with. $105 for the kit and another $15 to buy the extra 18" long 3.0" Dia.

Phil, you said you successfully turned the couple into an electronics bay. When you say coupler, are you talking about the coupler at the payload section? Can you describe it a little more?

I appreciate all the help.

Mike

Reply to
Mike

I modified my PML Endeavour to use electronic deployment with motor backup. The change is pretty simple. I added some wires going through the piston bulkhead. On the bottom (motor) side I just had the stripped ends of the wires to twist onto the ejection charge leads. On the top side I terminated the wires with a couple of two pin Deans plugs (a commonly used connector in the R/C world). I then had some long wires coming from the payload section terminated in mating Deans connectors.

The Deans connectors hold firmly enough so that I am not concerned about them coming apart during flight but they will pull apart during the ejection process.

I actually had two pairs going through the coupler so that when I flew using a hybrid motor, I could also have a backup timer.

Reply to
David Schultz

behind the

stripped

connectors.

electronics bay.

So how do you get the charge at the bottom of the rocket, underneath the piston but not block the charge from the motor and not fall out (or get blown out) of the rocket?

Thanks, Mike

Reply to
Mike Kordik

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