Rocketry Planet

CEDAR CITY, Utah USA — AeroTech has engineered a new, greatly improved G80T Blue Thunder™ single-use model rocket motor, which is being shown for the first time to attendees of the iHobby Expo trade show in Chicago, IL from October 18-21.

The motor, which has been under development since July of 2006, features an all-new molded phenolic casing with a built-in thrust ring, and ships with a FirstFire Jr.™ 2-lead igniter. More importantly, it generates a total impulse over 40% greater than that produced by the current-generation G80T, along with a gorgeous translucent blue exhaust plume studded with prominent "mach diamonds".

AeroTech's new and improved G80T.

"We used every trick in the book on this motor, and then invented some new ones" stated AeroTech/RCS president Gary Rosenfield. "As AeroTech's flagship single-use model rocket motor, we wanted the new G80T to embody the various casing and propellant technologies that we've been developing over the past few years, and to meet or exceed the performance and features of competitive offerings in as many areas as possible."

Ever since the November 2004 release of the first redesigned G80T in the current-generation molded casing, some AeroTech customers have expressed disappointment in the loss of total impulse from the previously certified 116 newton-seconds using a built-up paper-phenolic case design, to under 100 newton-seconds in the molded version. The loss was a consequence of translating the earlier motor design to the molded casing, which required a heavier case wall and substantial insulation thickness to protect it from excessive heating caused by the original G80T's "C-slot" propellant grain geometry.

The new G80T uses a dual "BATES" center core-burning grain configuration. This eliminates the need for extra case insulation and allows the largest diameter grain possible with a full 62.5 grams of propellant, the maximum permitted for a "legal" model rocket motor. The propellant composition was optimized to increase density and specific impulse (Isp) as much as practical within the parameters of AeroTech's DOT shipping classification and the inherent limitations of small rocket motor design. The nozzle exit cone was molded with a higher expansion ratio to increase motor efficiency. Other, proprietary design techniques were used as well.

Combined, these improvements have resulted in a delivered total impulse in excess of 130 newton-seconds, the highest ever achieved for a production single-use model rocket motor. The actual total impulse will be revealed once National Association of Rocketry (NAR) certification is granted for the new design. All this was accomplished without the use of exotic propellant chemicals or excessively high chamber pressures that could compromise motor reliability and safety.

The new G80T will be available in time delays of 7, 10 and 13 seconds. The 4-second delay has been discontinued, and customers are advised to use the next longer delay time increment for their rockets, due to the greatly increased total impulse. Other specifications of the new G80T include a burn time of 1.7 seconds, loaded weight of 128 grams, fired weight of 59 grams, diameter of 1.125" and a casing length of 4.88". The molded aft thrust ring has dimensions of 1.25" diameter X .25" long. Though the new G80Ts have a different exterior appearance due to the molded aft thrust ring, they will be clearly marked to differentiate them from the older G80Ts.

No user certification is necessary to purchase the G80T, though customers must be at least 18 years of age. AeroTech is now accepting orders for the new G80T motor and anticipates NAR certification to be received in late October to early November. Deliveries to dealers and distributors are expected to begin in late November.

A representative thrust curve of the new G80T, the NAR certification document, and motor instructions will be posted to the AeroTech Resource Library at http://www.aerotech-rocketry.com/ as soon as they become available.

AeroTech Consumer Aerospace is a division of RCS Rocket Motor Components, Inc., Cedar City, UT.

Reader comments:

#1 New G80

Any guess as to the price? Are we looking at a $35 G-class motor? It's like Aerotech wants to keep anyone from ever starting in the composite line... Hobby reload cases are $70 - $80 -- you don't dare fly them anymore...

MikeyR on 10-18-2007 01:01 PM

#2 Comparative Risk

I don't dare fly the SU motors. I've attempted to fly exactly two Aerotech single use motors (one a G80), and have gotten two blown-up rockets for my trouble! My Rouse Tech hardware and G64W and G71R reloads haven't had any problems. I was hoping that "improved reliability" would be one of the features of the new G80.

William
NAR L1

William Slaughter on 10-18-2007 03:24 PM

#3

I have flown dozens of AT SU motors. I too have had CATOs but I could count them on 2 fingers. (a G40 that spat the nozzle and an F25 that blew the forward end) Both times AT has replaced the motor and given me a kit for the one that was destroyed (the F25 toasted the kit)

-Aaron

heada on 10-18-2007 03:53 PM

#4 Many AT SU Catos

I agree with Aaron. I have flown many SU Aerotechs without experiencing catos. The very few problems (two or three in seven years) I have seen have usually been from tight igniters or otherwise plugged nozzles. I have heard about catos from extra hot igniters.

William,
My first thought would be the igniters you are using. My second concern would be how your motor were stored or handled before being launched. Are they all from the same vendor? Is it possible that your motors are being exposed to extreme environmental conditions, such as very high or very low temperatures or high humidity? Are you using the copperhead, first fire jr., or some other kind of igniter. Are the igniters very energetic, with lots of pyrogen? Are you using a 12 volt system? When you don't have a cato, does the igniter get spit?

Steve_Shannon on 10-18-2007 04:26 PM

#5

Copperhead igniters, 12v, and yes, it's pretty much always hot and humid here is Houston. They were handled carefully while in my possesion, but who knows about their life before that. Obviously my experience couldn't be the norm, but I'm pretty well equiped with reloadable hardware and stocked up on G71R reloads, so I don't have a great incentive for further SU experimentation right now. I must admit that the extra oomph would be nice, though. I can't comment on whether or not the igniter gets spit out when the motor does not cato, as I'm two for two on catos.
William

William Slaughter on 10-18-2007 04:49 PM

#6 G80

I too have had a few CATOs- all of them due to faulty Aerotech
G80's. The first time, at Virginia Tripoli's Battlepark, I had one simply explode
on the pad inside an old NCR Eliminator. Blew out one side and shredded the
MMT. The second one lacked the impulse (as the article mentioned) and burned
itself out resulting in minor rocket damage. I sent the motor casings back to Aerotech and they were replaced free of charge- great!
Second go around in an Aerotech Sumo and the G80 burned like crazy, without much impulse, totally cooking the MMT and inner bodytube.

So, I think this is good news. And since this motor is the only SU motor I've had any problems with, I'll try them again. Fingers crossed.

Paul53b on 10-18-2007 07:38 PM

#7

If I recall right there have been some problems when the new molded casings have been introduced.
Currently there are no "above the norm" (>1-2% failure) problems, as far as I can tell.
According to Gary, the casings are sensible to impact, so handling them with care is paying off.
Keep an eye on how the dealer is storing and handling them. If he's throwing them around you might want to try an other source.
I actually have seen one instance (EARS launch in the UK) where I saw a "way above the norm" failure rate and was attributing that to a bad / maybe old batch of motors of unknown source and (handling) history.

And yes, clogged nozzles allways can be a problem. There is a reason why the Copperhead still is a smart construction.
I wouldn't ever use anything else on a SU motor!

Juerg

Juerg on 10-19-2007 04:01 AM

#8

Has anyone noticed that this casing shown looks like the roadrunner casing with AT's custom yellow delay plug added to the end?

I flew a newer Ellis Mountain G35 two weeks ago and it was made with the roadrunner casing as well.

Is roadrunner selling his casing to others now?

Art Upton on 11-22-2007 12:37 PM

#9

Could it be that Roadrunner is making the new Ellis motors? Or visa versa?

ddmobley on 11-22-2007 12:42 PM

#10

Quote:

Could it be that Roadrunner is making the new Ellis motors? Or visa versa?

Roadrunner sells motors but doesn't make them. The molded case is a major investment into making them reliable and low cost.

jsdemar on 11-22-2007 03:58 PM

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