Rocketry Planet

CEDAR CITY, Utah USA — The National Association of Rocketry (NAR) Standards & Testing (S&T) Committee has certified AeroTech’s new E20W model rocket motor.

AeroTech's new E-class single-use E20 was certified by NAR S&T.

MORE ON THIS STORY:
• AeroTech E20W model rocket motor product flyer.

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• AeroTech E20W model rocket motor cut-away view.

The motor features an all-new molded phenolic casing with a built-in thrust ring, a molded delay/ejection bulkhead and ships with a FirstFire Jr.™ 2-lead igniter. Delay times will be initially offered in 4 and 7 seconds, though a 10 second delay was also certified. The suggested retail price of the new E20W is $19.99 per 2-pack.

NAR certified test values include a total impulse of 35.0 N-sec, burn time of 1.60 seconds, peak thrust of 34.9 newtons and an average thrust of 21.8 newtons.

The motors will soon be in production and shipments to dealers and distributors are expected to begin within the next few weeks.

The NAR certification document for the new E20W is now available for download in PDF format from the "Certification Documents" page of the AeroTech Resource Library at http://www.aerotech-rocketry.com. The E20W motor instructions are also available for download from the "Instructions" page of the Library.

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

Reader comments:

#1 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

I would like to begin by saying great motor, great delay targets.

I have attached the PDF of the certification document. The delays as tested are all over the place. I wonder how close they came to even being certified. Also we are in a time warp because it was tested negative one month ago.

This is a perfect mass-market product. I would emphasize the production process of making the delays as consistent as possible because the grain geometry and thrust curve seem to cause a tail wags the dog thing on delay accuracy. It has to be worse with temperature of operation variances. BTW nice photo of the product in operation on the brochure.

Jerry

Just Jerry on 10-29-2009 07:20 PM

#2 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

This is an improvement over the E15s and E30s in that it can properly use a FirstFire Jr. igniter. The copperheads are such crap, and on the older 24mm motors the larger head of the FF Jr. igniter tended to get stuck in the nozzle and cause catos. I kinda like the regressive thrust curve too- fast of the pad.

chadair on 10-29-2009 08:15 PM

#3 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

The delays as tested are all over the place. I wonder how close they came to even being certified.

I'm not sure what you mean. The delays are able to be +/- 20% of the stated value and they are well within this value. I haven't tried to take this delay data and generate a std dev but there aren't that many points so it may be a silly exercise anyway. +/- 1.4 seconds (at 7 second nominal delay) isn't going to cause most rockets much of an issue.

UncleVanya on 10-30-2009 08:56 AM

#4 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

The delays are able to be +/- 20% of the stated value

I think those standards ought to be tightened up a bit. I am not sure where it ought to be but say I design a rocket where the optimal delay is 8.5 seconds and I buy the E20-7 but the delay occurs at 5.6 seconds (minus 20%). That's a full three seconds before the rocket hits apogee. If they start making the E20-10 and I get a bonus delay of plus 20% (2 extra seconds) that means that motor is deploying at 12 seconds and my rocket has been falling for 3.5 seconds. It may be survivable but it's rough on the airframe.

Regardless, I am going to buy this motor at some point anyways. I have a Quest Full Moon with a 24mm motor mount that is begging for a E20-7.

-Dave

DAllen on 10-30-2009 03:51 PM

#5 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

I think those standards ought to be tightened up a bit.

I do too but, considering they used to be tighter, it's not going to happen.

billspad on 10-30-2009 06:28 PM

#6 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

I do too but, considering they used to be tighter, it's not going to happen.

What was the old standard?

UncleVanya on 10-30-2009 06:35 PM

#7 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

This industry needs more customers and more future customers. The AeroTech SU 24mm E20-4,7W is exactly the right product at the right time to deliver this needed benefit.

Jerry

Just Jerry on 10-30-2009 07:09 PM

#8 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

What was the old standard?

1 second

billspad on 10-30-2009 10:33 PM

#9 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

1 second

Bill, why won't it happen? +/- 1 sec seems very reasonable. Why was it changed in the first place?


Mark

markkoelsch on 10-31-2009 11:08 AM

#10 Re: Article: NAR S&T certifies the new AeroTech E20W 24mm SU motor

Quote:

Why was it changed in the first place?


Mark

From the 2006 ROP
(This modifies the requirements at 7.8.6 which starts: "Production lots shall be corrected, destroyed, or retested by the manufacturer under any of the following conditions:")

Quote:

SUBMITTER: Gary C. Rosenfield, RCS Rocket Motor components
RECOMMENDATION: Revise text to read:
(4) If the time delay of any test item varies more than 1.5 seconds or 20
percent, whichever is greater, from the established mean time delay value of
the rocket motor or motor-reloading kit. In no case shall this variation exceed
3 seconds.”
SUBSTANTIATION: It is very difficult to maintain a time delay tolerance of
+/- 1 second on some model and high power motors for a number of reasons
including ignition transients, effect of motor temperature and pressure on
delay burn rate, and exact determination of motor burnout. An extra 0.5 second
tolerance will not affect safety.
COMMITTEE MEETING ACTION: Accept
NUMBER ELIGIBLE TO VOTE: 31
BALLOT RESULTS: Affirmative: 20
BALLOT NOT RETURNED: 11 ARNOLD, BOWES, BULIFANT, COLON,
CONKLING, FADORSEN, GRUCCI, HANSON, HENDRICK, LAIB, PIER

The same reasoning was provided in the proposal to change 8.1.7(b) and 8.2.7(b) which cover certification testing of model and high power rocket motors.

The previous standard was +/- 1 second or 20 percent, whichever is greater but not more than 3 seconds. For a nominal 7 second delay the standard changed from +/-1.4s to +/- 1.5s. For delays longer than that there was no change. The primary impact is on delays shorter than 7 seconds.

UhClem on 10-31-2009 11:58 AM

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