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  #21  
Old 01-11-2013, 07:02 PM
Jerry Irvine's Avatar
Jerry Irvine Jerry Irvine is offline
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These motors are good to 1/2 the model rocket liftoff mass limit. They have 1/2 the model rocket propellant mass limit. [Trip Barber rule. Blue ribbon committee. 1984]

Suggestion from the people at Jerry. Align the FAA 125g limit to the DOT and the NAR and the NFPA limits.

Or better, make the ATF no limit under a certain (1 meter per second) burning rate be exempt under ATF, plus now DOT and USPS. Safety and liberty saved, and no adverse impact.

Well, except to the credit card of the user! GDP Growth and tax revenue increase. . . .

I want to buy a 125g FAA exempt motor in hobby stores. I want to put it in an airframe that limits altitude to football fields most of the time, to a mile most of the time and whatever in a minimal mass rocket. Damage control.

Model rocketry. Zero death rate. >800m launchings and under 5 serious injuries and that includes climbing trees to recover them! Model rocketry is as safe as safe can be defined in human existence.

Bow and pray: GH Stine, Orville, Vern, etc. No, really.

Last edited by Jerry Irvine : 01-11-2013 at 07:29 PM.
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  #22  
Old 01-11-2013, 07:03 PM
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Earl Earl is offline
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Quote:
Originally Posted by stefanj
Wild-arse guess:

Down the road a bit we'll get the 29mm high-thrust "E".

That is, a port-burning E in the same casing as the F15.

Hopefully much more reliable than the old FSI E60!



Yes, hopefully MUCH more reliable!


Earl
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  #23  
Old 01-11-2013, 07:08 PM
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Jerry Irvine Jerry Irvine is offline
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Quote:
Originally Posted by Earl
Yes, hopefully MUCH more reliable!
The basic technology has not changed in 2000 years.
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  #24  
Old 01-11-2013, 07:37 PM
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Carl@Semroc Carl@Semroc is offline
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This is some of the best news for model rocketry in a while! Congratulations to the engine gurus at Estes for this accomplishment. They are essentially a "bring back" of the Centuri Mini-Max "EB" engines from 1971. I never got a chance to fly those because it happened just after Semroc went insolvent and I was starting a career in electronics.

They are very close to these Mini-Max engines in specifications and probably even closer to the actual delivered performance. Granted, they are not the port burning for high lift, but they do fill a need and will be a lot of fun to watch.

The slow ramp up and low peak thrust will present challenges for heavier rockets, but they ARE mid-power engines and most mid-power rockets are flown off rods longer than 3 feet. I agree with John that the biggest problem will be finding the rockets.

NOW we can finally do a two-stage SLS Firefly!
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  #25  
Old 01-11-2013, 09:25 PM
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Quote:
Originally Posted by dlazarus6660
Bill, were these the motors you guys were testing?



You know I can't tell you if they were or weren't.
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  #26  
Old 01-11-2013, 09:39 PM
Jerry Irvine's Avatar
Jerry Irvine Jerry Irvine is offline
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Quote:
Originally Posted by Carl@Semroc
The slow ramp up and low peak thrust will present challenges for heavier rocket
I disagree. I wrote a program that took into account thrust before liftoff for composite motors with a build-up period. The only issue with those cases is the thrust on the moment of "thrust vs. gravity" till "launch rod departure speed" is achieved. It is actually less of a problem for BP vs. (old school) APCP.

I believe in 1/8 x 18", 1/8 x 36", 1/4" x 48" and 1/2" x 72" rods as a general rule now. Rails of 3 and 6 feet. depending on power.

Nothing wrong with two piece steel or aluminum with steel connectors.

Jerry
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  #27  
Old 01-11-2013, 10:36 PM
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Since I don't know how to attach a video here I've instead provided a link to the very first
F two stage rocket I tested at Estes. Sorry but this clip only shows the first stage engine and not the ignition of the second stage since my camera shut down. This model is two inches in diameter.

NO these motors don't have a big kick off the pad but they have a long burn, couple that to an upper stage with another three seconds of burn and you have a real high flying rocket. Like I stated before I've flown 24 ounce rockets with NO problem at all with these motors.



http://johnboren.com/F_Two_StageBoost.wmv


John Boren
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  #28  
Old 01-12-2013, 12:25 AM
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BEC BEC is offline
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Quote:
Originally Posted by Carl@Semroc
This is some of the best news for model rocketry in a while! Congratulations to the engine gurus at Estes for this accomplishment. They are essentially a "bring back" of the Centuri Mini-Max "EB" engines from 1971. I never got a chance to fly those because it happened just after Semroc went insolvent and I was starting a career in electronics.

They are very close to these Mini-Max engines in specifications and probably even closer to the actual delivered performance. Granted, they are not the port burning for high lift, but they do fill a need and will be a lot of fun to watch.

The slow ramp up and low peak thrust will present challenges for heavier rockets, but they ARE mid-power engines and most mid-power rockets are flown off rods longer than 3 feet. I agree with John that the biggest problem will be finding the rockets.

NOW we can finally do a two-stage SLS Firefly!


And you have some very suitable kits in your SLS line already. I've an SLS AeroDart in the ready-to-finish stage and already have a 29mm mount for it. Hmmmmmm........
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  #29  
Old 01-12-2013, 08:29 AM
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Quote:
Originally Posted by JumpJet
Since I don't know how to attach a video here I've instead provided a link to the very first
F two stage rocket I tested at Estes. Sorry but this clip only shows the first stage engine and not the ignition of the second stage since my camera shut down. This model is two inches in diameter.

NO these motors don't have a big kick off the pad but they have a long burn, couple that to an upper stage with another three seconds of burn and you have a real high flying rocket. Like I stated before I've flown 24 ounce rockets with NO problem at all with these motors.



http://johnboren.com/F_Two_StageBoost.wmv


John Boren


Hi, John !

I was hoping the video showed staging, etc.

My main concern would be weather-cocking on breezy days. I see this motor as being fine on dead calm days, or on models with very little fin area.

Any word on pricing and packaging, yet ?

Dave Fitch
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  #30  
Old 01-12-2013, 09:03 AM
Jerry Irvine's Avatar
Jerry Irvine Jerry Irvine is offline
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Listening to the audio portion of that video it appears considerable tube ID is shot through the nozzle mid burn and onward. How much of the casing is eroded during the firing? Thanks for releasing the Estes F15 or, 29mm 50F14-4-VBP (ILP method). It has already stimulated some kit sales here. That didn't take long!

Just Jerry

My #1 Estes motor wish is a high thrust D in the E casing. Gain experience for the future high thrust E in the F casing . . .

Here's a blow up of the photo of the motors from MIT/TRF.
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Last edited by Jerry Irvine : 01-12-2013 at 10:08 AM.
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