casting delay elements

[fyrwrxz]

Okay-Stealth6 started this train of thought for me. Does anything specifically prohibit me from casting my own delay slug for a production motor? The reason I ask is I have some extra smoke comp (un mixed) I didn't use from a video SFX project they just gave me to get rid of and S6 got me to thinking. It's not propellant, but with my new element, would it be considered an altered motor? We DO drill our delays, right? What If I could duplicate the factory delay formulae but add a couple more seconds to get a 16-18 sec delay in the same geometry? I like to fly the long burns and the delay is typically way too short for motor deploy backup or primary use. I understand about being under pressure and flame front propagation and chamber pressures and propellant type (aerotech anyways). The grain itself is not my problem-it's the legal issue of modified motors. Smart people live here-is this a stupid question??

[cavecentral]

Okay-Stealth6 started this train of thought for me. Does anything specifically prohibit me from casting my own delay slug for a production motor? The reason I ask is I have some extra smoke comp (un mixed) I didn't use from a video SFX project they just gave me to get rid of and S6 got me to thinking. It's not propellant, but with my new element, would it be considered an altered motor? We DO drill our delays, right? What If I could duplicate the factory delay formulae but add a couple more seconds to get a 16-18 sec delay in the same geometry? I like to fly the long burns and the delay is typically way too short for motor deploy backup or primary use. I understand about being under pressure and flame front propagation and chamber pressures and propellant type (aerotech anyways). The grain itself is not my problem-it's the legal issue of modified motors. Smart people live here-is this a stupid question??

My GUESS is, no you can't. Manufacturers have to be within 20%. Not sure how used test this.

I think the drilling grains was a fairly recent thing even, although it was done all this time on single use back in the day.

[fyrwrxz]

Yeah, cc-I think you nailed it right there. If I tell the RSO it's an I59-18, he mite get a little suspicious...dang! OTH, this is just backup...it could be a 'bonus' delay....the alt would do the real work. I'm just looking for a smoke trail at hi alt like s6 was asking about. Hmm-back to plan 'b', which I haven't figured out yet. Oh well-thanks for the input.

[Bazookadale]

It would be an unapproved modification to the motor and therefore can't be flown at a launch that requires certified motors. I believe you could fly at an EX launch.

[G_T]

Just as a philosophy thing - the difference between a delay element and propellant is that there isn't enough delay element to pressurize the motor, and the material has a rather slow burn rate and weak gas production. But you might want to think of it as a propellant of a different formulation. It's in the motor, and designed to burn. It contains materials that, if introduced into the motor during the high thrust portion of the burn, will alter the burn characteristics. You indicated a smoke mix. That usually contains a fair bit of a metal, which is a fuel. And I worry a bit about "smoke mix". At least the one I use should not be pre-mixed as it is much more hazardous in that state than as separate chemicals or as a cast grain. Smoke mix is formulated and produced using the same procedures as a propellant grain, and for the same reasons.

Gerald

[cavecentral]

It would be an unapproved modification to the motor and therefore can't be flown at a launch that requires certified motors. I believe you could fly at an EX launch.

+1 - TRA Research launch would be the way to go.

[Polyalcoholic]

Most 'smoke mix' formulas are chlorate based. Chlorate mixture burn rates increase dramatically at elevated pressure.
Not recommended.

[cavecentral]

Most 'smoke mix' formulas are chlorate based. Chlorate mixture burn rates increase dramatically at elevated pressure.
Not recommended.

In research they are a slow propellant that will still continue to burn after the pressure drops from burnout. They are still a form of APCP. I don't think he is referring to colored smoke mixes from the fireworks stores.

[Johnly]

+1 - TRA Research launch would be the way to go.

Modified comercial motors are outside the TRA Research code.




3.2. Tripoli Research Definitions
3.2.1. BOD. Board of Directors of the Tripoli Rocketry Association, Inc.
3.2.2. Rocket Motor. As used in this code, Rocket Motor shall refer only to Composite Propellant, Sugar Propellant, commercial black powder, and Hybrid Rocket Motor.
3.2.2.1. Certified Motor. Any commercial motor which has been certified by Tripoli Motor Testing (TMT) and/or NAR Standards and Testing (S&T) and/or CAR Motor Certification Committee, or at one time was certified and has expired, or has been decertified.
3.2.2.2. Research Motor. Any non-certified motor made for personal use that may or may not contain commercially available components. Research motors shall not be sold or distributed for a profit.

[G_T]

Seems to me clearly to fall under 3.2.2.2. That motor combination was never certified. It is not being sold, so can't be for profit. It contains commercially available components, which is allowed.

Gerald

[fyrwrxz]

Thanks, guys! I really was asking about the modded motor, not about the formula for the grain. I just referenced the smoke mix as a train of thought. No, I don't store anything mixed, smoke or other-wise. This was really just a cross over from what i had going and Stealth6 was asking some pretty cool questions, so the wheels started turning. I guess it's back to the EX lab...I was just trying to find an easy way (cheat?) around making the whole thing.

[Handeman]

Thanks, guys! I really was asking about the modded motor, not about the formula for the grain. I just referenced the smoke mix as a train of thought. No, I don't store anything mixed, smoke or other-wise. This was really just a cross over from what i had going and Stealth6 was asking some pretty cool questions, so the wheels started turning. I guess it's back to the EX lab...I was just trying to find an easy way (cheat?) around making the whole thing.

If you want a definative answer, contact Ben Russell. He's the Chairman of the Tripoli Research Committee and approves all the EX launch requests for the prefectures. His contact info is on the Tripole site under Contact -> Tripoli Research.

His TRA handle is "ben" so you can send him a PM, although I don't know how often he is on here.

[G_T]

I sent an email to Ben to point him to this thread.

Gerald

[ben]

Seems to me clearly to fall under 3.2.2.2. That motor combination was never certified. It is not being sold, so can't be for profit. It contains commercially available components, which is allowed.

Gerald

Gerald is right. A research motor can contain commercial grains and ex smoke grains or any combination. The motor must be flown at a Tripoli Research launch by a Tripoli member who is TRA level 2 or above.

Ben

[fyrwrxz]

Woot! Commercial grains and a custom delay element?? Too much fun. Let the mixing begin. Never done a small endburner like this.

[JDcluster]

Let the case bubbling begin!

A long smoke grain WILL wreck your hardware!

That is why I don't normally use the smoke / delays in my motors.


JD