Sky rippers!

The Rocketry Forum

Help Support The Rocketry Forum:

BlueNinja

Well-Known Member
Joined
Jan 18, 2009
Messages
2,700
Reaction score
1
Hey, more info on the SRS hybrids... looks like the 29mm 3 motor set will be 115.00, about the same as the AT set... Reloads are only 25.00 for the 3pak and made out of ABS... Wonder how much of a difference in FX that will be?


Sweet, I can't wait. :D Especially for the 29/75 G load :D :D

This will go nicely with my avatar.
 

Chuck Rudy

Well-Known Member
Joined
Jan 20, 2009
Messages
829
Reaction score
0
This could be great for the hybrid crowd......a gas motor or two you can use under FAR 101.
 

DynaSoar

Well-Known Member
Joined
Mar 15, 2004
Messages
3,022
Reaction score
0
Originally posted by Blue_Ninja_150
Hey, more info on the SRS hybrids... looks like the 29mm 3 motor set will be 115.00, about the same as the AT set... Reloads are only 25.00 for the 3pak and made out of ABS... Wonder how much of a difference in FX that will be?


Sweet, I can't wait. :D Especially for the 29/75 G load :D :D

This will go nicely with my avatar.
Now if they (or someone) will provide for a non-pyro ejection system that works with the motors, and a ground support package so that people don't have have to construct one piece meal, they could very well produce the first hybrid not requiring NAR/TRA level certification.
 

Todd Moore

Well-Known Member
Joined
Jan 28, 2009
Messages
274
Reaction score
0
Actually, due to a misguided NFPA regulation, ALL hybrids require a L1 certification at this point. The clubs do allow L1 certs on H and I hybrids, However. With certified G motors in the works, however, I hope this is something that can be changed.
 

shockwaveriderz

Well-Known Member
Joined
May 25, 2002
Messages
2,472
Reaction score
1
todd: are you in contact with "the powers that be" about exempting the G level hybrid from L1 cert requirements? Obviously since it is G power it still cannot be purchased by those under age 18 but it can be used with adult supervision.....

I love this.....technology pushing the envelope of the regulations requiring that they be updated.....great work Todd....
 

DynaSoar

Well-Known Member
Joined
Mar 15, 2004
Messages
3,022
Reaction score
0
Originally posted by Todd Moore
Actually, due to a misguided NFPA regulation, ALL hybrids require a L1 certification at this point. The clubs do allow L1 certs on H and I hybrids, However. With certified G motors in the works, however, I hope this is something that can be changed.
"Indeed." -- T'ilq, Spock and other cool aliens.

"At this point" is my point. An integral ejection system would go far to effecting the change, a non-pyro based one more so. I don't have the NFPA regs, but I'd bet they include the ability for NFPA to institute of a waiver of a particular point pending the next full version given suitable cause and evidence.

I would hope NFPA would see the logic in allowing MPR hybrids without certification. They are, after all, inherently safer than APCP of the same impulse. They're also fairly impossible to abuse in the manner that seems to give a few folks at BATF reason for living.
 

Missileman

Well-Known Member
Joined
Apr 21, 2011
Messages
786
Reaction score
0
I have often wondered about the use of pyro for ejection.
Even the CO2 type ejection systems use a charge to puncture the seal on the tank.
Why can't another system be used. something similar to the mechanism in a CO2 bb gun that would be actuated by a servo.
 

Loki

Well-Known Member
Joined
Apr 17, 2009
Messages
279
Reaction score
0
Originally posted by missileman
I have often wondered about the use of pyro for ejection.
Even the CO2 type ejection systems use a charge to puncture the seal on the tank.
Why can't another system be used. something similar to the mechanism in a CO2 bb gun that would be actuated by a servo.
Completely non-pyro ejectionsystems have been done many times. I've seen spring actuated systems used several times and there's really no limit to the number of methods that can work. People often try new methods, "just to see if I can make it work" and I think that's great. However, for a method to get wide spread use it has to be better than what is already there. Servos (even the samllest ones) are larger than an ematch and a pinch of BP. What's more they need electric power and a circuit to drive them. Servos are also expensive and delicate when compared with the pyrotechnic alternatives.

So let' see, they are heavier, they are more expensive, they take more room, they can break, they require a battery, and at the end of the day they don't really do the job any better.
 

DynaSoar

Well-Known Member
Joined
Mar 15, 2004
Messages
3,022
Reaction score
0
Originally posted by Loki
Completely non-pyro ejectionsystems have been done many times. I've seen spring actuated systems used several times and there's really no limit to the number of methods that can work. People often try new methods, "just to see if I can make it work" and I think that's great. However, for a method to get wide spread use it has to be better than what is already there. Servos (even the samllest ones) are larger than an ematch and a pinch of BP. What's more they need electric power and a circuit to drive them. Servos are also expensive and delicate when compared with the pyrotechnic alternatives.

So let' see, they are heavier, they are more expensive, they take more room, they can break, they require a battery, and at the end of the day they don't really do the job any better.
A pin valve to fit a Copperhead or Daisy CO2 cart with a solenoid actuated by a standard timer, baro sensor or magnetic apogee detector. Simpler and lighter than any mechanical device.

Better? Not much of an issue. Sufficient is sufficient. Battery? So does an ematch.

My little mission is to see to it that a viable non-pyro alternative is available. As long as people *have* to fiddle with black powder by hand, it's going to be very hard to get hybrids allowed without L1 certification.

A CO2 cartidge is less than a dollar. So's a pin valve. A solenoid, a few bucks. If a manufacturer like Daisy or Crosman already has them maunfactured, I'd say maybe $20 or $30 for something that screws onto the cartridge. The same electronics that'd run a BP charge would run this, and cost more than the rest of the stuff. A hybrid motor and GSE costs more too. It's in the reusing that it pays. Same for CO2 cartridges.
 

Elapid

Well-Known Member
Joined
May 2, 2009
Messages
1,734
Reaction score
0
rockets from Vashon ejected a chute...
i don't recall any bp

maybe the technique could find new usage?
 

DynaSoar

Well-Known Member
Joined
Mar 15, 2004
Messages
3,022
Reaction score
0
Originally posted by Elapid
rockets from Vashon ejected a chute...
i don't recall any bp

maybe the technique could find new usage?
IIRC, it was freon, which is not a Good Thing to be blowing out freely into the atmosphere.

I have a copy of Terry Stroud's reasoning why they chose CO2 ejection for the Aurora: BP loses its punch with altitude. I tried to upload it but (1) the original is a .doc file (not allowed) and (2) even zipped, it's 173K, too big.

Where to put it? Is there a files section here?
 

BlueNinja

Well-Known Member
Joined
Jan 18, 2009
Messages
2,700
Reaction score
1
Originally posted by Elapid
rockets from Vashon ejected a chute...
i don't recall any bp

maybe the technique could find new usage?
As you recall, the motors utilized Freon. at the top of the "combustion chamber" there was a little hole. Above that, there was a series of paper disks that would leak freon, thus the user could modify the delay. After the gas seeped through, there was a system of clamps and a spring. The clamps were opened by the freon, and pop.

This is if I read the HBMR 4th edition right :eek:
 

Elapid

Well-Known Member
Joined
May 2, 2009
Messages
1,734
Reaction score
0
maybe a Nitrous 'leak' could be used similarly, i was not suggesting the use of freon by any stretch of the imagination.
 

BlueNinja

Well-Known Member
Joined
Jan 18, 2009
Messages
2,700
Reaction score
1
Problem is, how would you keep it form expandong out on the pad? Some clubs have a LONG setup/launch time ratio (that sounded stupid) and nitrous expands with heat, right? so, you might pop your chute on the pad if you waited more than 10 minutes after filling.... Just a thought. Ah well, before this comes out I'll probably have an altimeter so no worries there...
 

Bill

Well-Known Member
Joined
Dec 23, 2010
Messages
484
Reaction score
0
Originally posted by Blue_Ninja_150
As you recall, the motors utilized Freon. at the top of the "combustion chamber" there was a little hole. Above that, there was a series of paper disks that would leak freon, thus the user could modify the delay. After the gas seeped through, there was a system of clamps and a spring. The clamps were opened by the freon, and pop.
You have that mostly right. A fitting at the top of the tank uses Freon presssure from the tank to force a multi-pronged clamp outward, holding the forward section of the rocket (containing the parachute) in place. The paper disks control how quickly that pressure can leak from that fitting back into the tank after the thrust phase is over and the tank is back to atmospheric pressure. Once the pressure leaks out, the clamp lets go, the top of the rocket separates from the tank and lets the chute out. There is never an ejection event, merely a separation.

I also seem to recall there was some tricky technique to stage these rockets, but cannot remember the details now.


Bill
 

Bill

Well-Known Member
Joined
Dec 23, 2010
Messages
484
Reaction score
0
Originally posted by DynaSoar
A pin valve to fit a Copperhead or Daisy CO2 cart with a solenoid actuated by a standard timer, baro sensor or magnetic apogee detector. Simpler and lighter than any mechanical device.

Better? Not much of an issue. Sufficient is sufficient. Battery? So does an ematch.

My little mission is to see to it that a viable non-pyro alternative is available. As long as people *have* to fiddle with black powder by hand, it's going to be very hard to get hybrids allowed without L1 certification.

A CO2 cartidge is less than a dollar. So's a pin valve. A solenoid, a few bucks. If a manufacturer like Daisy or Crosman already has them maunfactured, I'd say maybe $20 or $30 for something that screws onto the cartridge. The same electronics that'd run a BP charge would run this, and cost more than the rest of the stuff. A hybrid motor and GSE costs more too. It's in the reusing that it pays. Same for CO2 cartridges.
The currently available commercial CO2 deployment system uses a small BP charge to puncture the cartridge. The problem is how to build a small and light non-pyro mechanism to reliably puncture the cartridge when it's time to deploy the chute, but not let the pressure leak out prematurely. BB guns have lots of beefy material to hold the cartridge firmly in place against a fitting so that it does not leak once punctured; nothing screws onto the cartridge. I do not think puncturing the cartridge as part of the prep process and then trying to contain the pressure until it is needed will be a practical approach.

The water rocket people have used wind-up toy mechanisms to deploy parachutes. That may be worth a look.


Bill
 
Top