Looking for one of these engines

[BRC]

Aerotech G78-4G Single Use Rocket Motor or
Aerotech G80-4T Single Use Rocket Motor

If ya happen to have one laying around !!

[ghrocketman]

I do not have any of those rite now, but those are fairly common engines.
Why dont you order some through Commonwealth or another of the online vendors ??

[BRC]

I've tried the first one is not made anymore and the
second is out of stock everywear I looked. !!!

[Shreadvector]

Aerotech G78-4G Single Use Rocket Motor or
Aerotech G80-4T Single Use Rocket Motor

If ya happen to have one laying around !!

The G80-4 is no longer made for a very good reason. The current production G80 motors have 137 Newton-Seconds of total impulse. They acheived this huge increase in total power obtained by using the maximum propellant mass allowed (62.5 grams) and an extremely efficient design: nozzle expanded better than the original and operating pressure is higher thanks to a new casing design.

As a result, the maximum size Model Rocket (3.3.pounds) which is usually around 4 inches in diameter, will NEED a 7 second delay time to reach apogee. The older version of the G80 motor had a lower total impulse, so a fat and heavy rocket would require a shorter delay time since they would not fly as high or fast.

Old version: http://www.nar.org/SandT/pdf/Aerotech/G80.pdf

New/current version: http://www.nar.org/SandT/pdf/Aerotech/G80-20071207.pdf

[Shreadvector]

By the way, the new G80 is so powerful, they had to tailor the grain geometry to keep the average thrust below 80 Newtons to comply with Model Rocket Motor limits.

IIRC there are 2 segments with different geometry. Note the lower "tail" at the end of the motor burn that brings down the average.


if you have some other unusual project that really needs a 4 second delay, I suggest going with RMS where you will have a choice of motors with a 4 second delay time.

[ghrocketman]

Better yet than tailoring the grain to keep it at 80n avg. thrust or less would be to TOTALLY GET RID OF THAT REQUIREMENT for definition of a model rocket motor.
Quite frankly, now that the APCP BATFE case has been won, I'd like to see ALL consumer rocket motors through at LEAST "P" class be on the hobby shelf with NO restrictions to use or purchase other than following the proper FAA regs for flight waivers.
Yes, I'd like to see the entire cert process eliminated.

[BRC]

The G80-4 is no longer made for a very good reason. The current production G80 motors have 137 Newton-Seconds of total impulse. They acheived this huge increase in total power obtained by using the maximum propellant mass allowed (62.5 grams) and an extremely efficient design: nozzle expanded better than the original and operating pressure is higher thanks to a new casing design.

As a result, the maximum size Model Rocket (3.3.pounds) which is usually around 4 inches in diameter, will NEED a 7 second delay time to reach apogee. The older version of the G80 motor had a lower total impulse, so a fat and heavy rocket would require a shorter delay time since they would not fly as high or fast.

Old version: http://www.nar.org/SandT/pdf/Aerotech/G80.pdf

New/current version: http://www.nar.org/SandT/pdf/Aerotech/G80-20071207.pdf


OK...I thought I would need the 4 second delay for my 4" Gemini Titan, but if you say the 7 sec delay will do Im on it !!!
Thanks for the insight..... :)

[Shreadvector]

OK...I thought I would need the 4 second delay for my 4" Gemini Titan, but if you say the 7 sec delay will do Im on it !!!
Thanks for the insight..... :)

Just MAKE SURE that when you buy them, they are the *NEW* G80-7 and not the old. The new packages have stickers loudly proclaiming the total-impulse. I had called Hobbylinc about that last year and they checked for me so I could get what I needed from the existing inventory.

[BRC]

Just MAKE SURE that when you buy them, they are the *NEW* G80-7 and not the old. The new packages have stickers loudly proclaiming the total-impulse. I had called Hobbylinc about that last year and they checked for me so I could get what I needed from the existing inventory.

Thanks...I emailed Hobbylinc as soon as I got your last reply, but it took two days for them to respond last time as well...Thanks Again

[stephen23648]

Yes, I sent a G80-4T to NARAM for sale but I do not think it got any attention so it should still be available.

[Mark II]

Commonweath Displays has the G78-4G (http://www.commonwealth.net/cgi-bin/info.pl?prodcode=AROG784G&url=at/sumotor.htm) in stock.

But as Fred explained, a 4-second delay with this motor may not be the best choice for your rocket, either.

http://www.aerotech-rocketry.com/customersite/resource_library/Certification_Documents/NAR/single-use/29mm_mr_su/g78g_nar_cert.pdf

MarkII

[Mark II]

Better yet than tailoring the grain to keep it at 80n avg. thrust or less would be to TOTALLY GET RID OF THAT REQUIREMENT for definition of a model rocket motor.
I'd like to see some loosening up there, too, but to do everything that you propose, first you would have to get everyone to throw NFPA under the bus. Good luck with that one. :rolleyes:

Is a G motor with 67.2 grams of propellant qualitatively different from one that has 62.5 grams of propellant? The former is "high power" and requires Level 1 certification, while the latter can be purchased and flown by anyone, as long as the purchaser is at least 18 years old. That's just crazy.

MarkII

[jetlag]

I thought the certification thing was gone now....?
Anyone can buy big motors now, right?
Allen

[BRC]

Commonweath Displays has the G78-4G (http://www.commonwealth.net/cgi-bin/info.pl?prodcode=AROG784G&url=at/sumotor.htm) in stock.

But as Fred explained, a 4-second delay with this motor may not be the best choice for your rocket, either.

MarkII


I took his advise and went with the new G78 with the 7 sec. delay...I am just about finished with this project but now trying to find out why I am having a rock sim discrepency with another gentlemen with this setup..

[gpoehlein]

I thought the certification thing was gone now....?
Anyone can buy big motors now, right?
Allen

Not exactly - the LEUP thing is gone - but you still need certification to buy (and fly) H motors and up. You just don't have to have an LEUP to buy them or to store them.

Greg

[ghrocketman]

Uhhh....yes I would like to see NFPA thrown completely under the bus for all individual consumer activities !
Just another NUISANCE act that provides un-needed control and intrusion into individual's rights.
The vast majority of laws enacted that intrude into individual freedom since WWII are ill-concieved nuisances that have served virually zero purpose other than to keep law writers in business.

[BRC]

Uhhh....yes I would like to see NFPA thrown completely under the bus for all individual consumer activities !
Just another NUISANCE act that provides un-needed control and intrusion into individual's rights.
The vast majority of laws enacted that intrude into individual freedom since WWII are ill-concieved nuisances that have served virually zero purpose other than to keep law writers in business.

A man after my own heart !! :D

[jadebox]

Uhhh....yes I would like to see NFPA thrown completely under the bus for all individual consumer activities !
Just another NUISANCE act that provides un-needed control and intrusion into individual's rights.

There is no "right to fly rockets." Thanks to the stuff in the NFPA, however, we have uniform laws across much of the country that allow us to legally fly rockets. If you think our certification program is onerous, just think what it would be like if you had to deal with locally drafted laws that would possibly conflict with state or federal laws and were different all over the country.

-- Roger

[BRC]

There is no "right to fly rockets." Thanks to the stuff in the NFPA, however, we have uniform laws across much of the country that allow us to legally fly rockets. If you think our certification program is onerous, just think what it would be like if you had to deal with locally drafted laws that would possibly conflict with state or federal laws and were different all over the country.

-- Roger


As a complete novice it is my intention to go thru the certification steps for my own well being...However, the is no specific "right" to do most anything, the Bill of Rights regulates what the Gov't cannot do to infringe in our inalienable rights..The Declaration of Independence says "The pursuit of life , liberty and the pursuit of happiness, like rocket building " !!!

As a Scuba instructor ther is no Law regulating certification as it is self regulated purely for liablility reasons as probably the rocket industry...I mean there are laws governing the making of scuba tanks and thier transports, as probably rockets engines....Thanks for letting me participate...

[jetlag]

I'm with GH on this:
If I can buy any HP motor I want and store it anyway I like, then rest assured, if I want to launch one, I will, regardless of whether Tripoli or NAR like it or not. As long as I let the FAA know I'll be punching into their airspace, so what?
Allen

BTW, I have no intention of going into HP, but if I want to go there, I can now...legally, it appears.

Allen

[ghrocketman]

The only good new regulations are those that BAN regulation of individual freedom.

Yes, I would like the HP cert process eliminated and I would like for ANY hobbyist at ANY time to be able to purchase, store, and fly any and all HP consumer rocket engines up to at LEAST "P" class, provided one files for the proper waivers with the FAA. As it is now, one does not need to file anything with the FAA as long as propellant mass is below 4.4oz total with rocket weight of something like 3.3 lbs or less. That alone would allow one to fly H motors on their own land with ZERO waivers.

Quite frankly, in my book the best rocketry is an un-regulated FREE-FOR-ALL !

There should be absolutely NOTHING in the NFPA that has ANYTHING to do with consumer/amateur rocketry as long as the events take place on PRIVATE land.
They (the gubmint) should butt their nosey SNOOTS out !

[Mark II]

My intention was not to spark a debate in this. I just wanted to point out that there is little chance that ALL motor regulations and certifications will go away any time soon, for reasons that Roger outlined. And gh, isn't that spoiled brat act getting a bit stale now?

MarkII

[jadebox]

I'm with GH on this:
If I can buy any HP motor I want and store it anyway I like, then rest assured, if I want to launch one, I will, regardless of whether Tripoli or NAR like it or not. As long as I let the FAA know I'll be punching into their airspace, so what?
Allen

BTW, I have no intention of going into HP, but if I want to go there, I can now...legally, it appears.


If your state has adopted the NFPA as law, then, no, you cannot legally fly HPR without being certified (or being a part of the government or a university - whatever the exemptions are).

And, if your state has not adopted the NFPA as law, then you'll likely run up against other laws - such as fireworks laws - that make it impossible to legally fly HPR.

-- Roger

[stephen23648]

Let us rejoice over the victory over the ATF and move onward. I thought this part of this site was dedicated to trade and I will personally deliver any part of my rocket motor collection anyone wants to but if you live near me and pay my gas expense. Or, I can investigate the UPS hazmat fees and do that too.

I am an unemployed Software Engineer/Senior Developer/Senior Programmer Analyst who needs to see my old Aerotech and Apogee motors to help pay the bills. I have collectors Apogee composite B and C motors as well as Apogee 10.5 mm A2 and B2 motors. I also have your average Aerotech F and G motors including the G80-4.