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Maelstrom

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Does anyone know of any low powered motors with a delay shorter than 2 seconds?
 

Johnnie

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C6-0; A8-0; B6-0; C11-0; D12-0...these are the only ones I know of shorter than 2 seconds, but these are used for staging only.
 

bobkrech

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Quest Micromax motors have a 1 second delay.

Estes and Quest booster motors have no delay, and Estes D and E plug motors have no delay.

Bob Krech
 

Maelstrom

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Yeah, but I still need the ejection charge.. and I'm really looking for something in the A-B range, not micro.
 

bobkrech

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What are you trying to do?

There should not be a need for such a short delay on any stable rocket that I can envision. A rocket on a B engine that could utilize a 1 second delay would weigh about 8 ounces and would have an apogee of only 36 feet. The maximum velocity would be less than 40 ft/sec and it would likely to be unstable.

Did I miss something?

Bob Krech
 

Maelstrom

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Although I have not had opportunity to test-launch it yet, I have a rocket that should separate into 3 pieces from the ejection charge and my goal is to simulate a CATO. SO, I'd really like a short delay A motor that will 'detonate' in plain view. Although the shortest delay I've seen is 2 seconds and with a B motor.

So I guess I need to find a balance that keeps it stable, and as close to the ground as possible but allow for ejection before the rocket starts to freefall.

Ideas?
 

bobkrech

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This is a possible solution, but it is an RSO's nightmare. You would have to prove that a safe recovery would occur before I would let you launch it at our launches.

In a 4.6 ounce rocket, a B6-0 at burnout is moving at 87 fps and has reached about 40 ft altitude. With a 4 ft launch rod, the launch velocity is 39 fps so the rocket is aerodynamically stable.

In theory, you could put some BP on top of a B6-0 to effectively have a zero delay ejection charge. This would "CATO" or "disassemble" your rocket. All components would have to be designed for tumble recovery since you would strip off a parachute or streamer at the deployment velocity.

This solution could work.

Bob Krech
 
A

Austin

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Estes had such a rocket for 18mm motors and as a matter of fact, it was called a "CATO". I have one in my collection and did not plan on building it, but the principle is the same. It flies on B6-0 and C6-0 motors, uses a piston ejection and it comes down on streamers and a parachute.

For more info, go to - http://www.dars.org/jimz/estes/est2071.pdf

Carl
 

powderburner

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Originally posted by bobkrech
In theory, you could put some BP on top of a B6-0 to effectively have a zero delay ejection charge.
I don't think you need to add any loose BP on top of the booster motor, the blow-through (normally used for staging) should be powerful enough to trigger any necessary deployment, if not too powerful.

As for:
This is a possible solution, but it is an RSO's nightmare. [/QUOTE]

Yes, the rocket's design sounds a little unconventional, but if the components will recover safely, what's the big deal? (Am I overlooking something?)
 

bobkrech

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Carl

Just goes to show there really nothing new under the sun.

Powderburner

Right about the possibility to not have to use BP, particularly if you use a piston as Carl noted previously with the ESTES CATO.

I tend to be conservative. I know how to design a rocket to look like it CATOED (even more so than the ESTES kit), but I'm not sure that everyone can do it correctly. If I were the RSO and the builder could answer the recovery questions to my satisfaction, then it would fly, otherwise it wouldn't. My safety questions and concerns are two-fold.

In the solution I proposed, there is a relatively high (disassembly) velocity near the ground so it is important that the pieces slow down and tumble recover. While a commercial kit will be proven safe by the manufacturer, a scratch-built may not have been flown before. As RSO I would want know how the rocket comes apart inflight and what the recovery expectations are.

Also it is important to only use A or B motors to keep the velocity low. There is always a temptation to use bigger motors which if the design were unstable, could prematurely disassemble at low altitude and high velocity under power and then you have a burning motor to contend with. As RSO I would like to know the CG/CP relationships of the model.

Bob Krech
 

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