Most powerful MPR engine?

[Green Jello]

Just curious while building my first 29mm motor mount rocket...what is the most powerful single use engine you can use without a L1 certification? Is it the AeroTech G80?

[JordanT]

That depends on how you like to measure it. The AT G80 has is the highest impulse single use, though that's a pretty weak distinction. The AT G75J (29/180 hardware) is 155N-s, and meets all the other requirements (<80N avg, <125g prop, <160Ns). If you switch over to CTI, you could fly a 159G54 (3 grain load), which has 159Ns, and 54N avg thrust.

If you're concerned about accel at launch, an AT G76G peaks north of 130N for a brief period, whereas the G80-T just cracks 90N, and the 159G54 will pull about 120 and change.

Now, if you don't limit yourself to MPR and are willing to get a longer casing (I believe that leaving 14.5" lets you go all the way to a 6XL CTI, the longest production/commercial 29mm), then you can slap a little I in there and see just how fast you can rip the fins off a rocket ;-)

[cjl]

I thought the restriction was still 62.5g propellant mass for any single motor, otherwise you get into HPR. If that's the case (it certainly used to be, but I have to admit, I haven't paid much attention to the details of the distinction between MPR and HPR recently), the AT SU G80 is the cutoff.

[JDcluster]

The 62.5 gram limit came from the class B laws at the time. Now that the ATFE case is over, the 62.6 grams has little meaning ( as far as I know).

JD

[KevinDunn]

Check the Combined motor list. HP motors are designated with (HP). There are several motors with more than 62.5 g that are not designated as HP.

[shreadvector]

The 62.5 gram limit is now 125 grams per the latest new version of N.F.P.A. 1125 (2012 edition).

7.6 Model Rocket Motor Limitations.
7.6.1 A model rocket motor shall contain no more than
62.5 g (2.2 oz) of propellant except as provided for in 7.6.1.1.

7.6.1.1 A model rocket motor manufactured only for sale to or use by individuals 18 years of
age or older shall be permit- ted to contain no more than 125 gm (4.4 oz) of propellant.
7.6.2 A model rocket motor shall produce a total impulse less than 80 N-sec (17.98 lb-sec).
7.6.2.1 A model rocket motor manufactured only for sale to or use by individuals 18 years of age
or older shall be permitted to have a total impulse not in excess of 160 N-sec (36 lb-sec).
7.6.3 A model rocket motor shall produce an average thrust of 80 N (17.98 lbf) or less.
7.6.4 A model rocket motor manufactured for sale to or use by individuals 17 years of age or
younger shall be designed to comply with 16 CFR 1500.85(8) and (9) of Consumer Product Safety
Commission (CPSC) Regulations.
7.6.5 The propellant of a model rocket motor shall contain no metal particles larger than
150 microns (100 mesh) and shall be designed to produce a minimum of ejected particles
or sparks.

[shreadvector]

In other words, there are some "HPR" noted motors with more than 62.5 grams but up to or less than 125 grams of propellant on the certification list that should now have the "HPR" prefix removed if they meet the rest of the Model Rocket motor requirements (i.e. still have 80N or less average thrust).

This also means we could have HUGE black powder Model Rocket Motors (if we dare).

[JordanT]

This also means we could have HUGE black powder Model Rocket Motors (if we dare).

Interestingly, it means you could probably get a full F (or baby G) in Black powder with a liftoff peak thrust well in excess of 120N (maybe 160+ with a deep enough core) and still end up with no more than 80N average thrust, making it capable of getting a 1.5kg rocket flying with a long "powered coast" phase. I don't expect anyone to go break altitude records with it, but it would be a fun burn to watch on the bigger kit rockets.

Kevin - thanks for posting the list; The options I posted appear to jive with the list.

[Rocketjunkie]

This also means we could have HUGE black powder Model Rocket Motors (if we dare).

Check ATF regs. Black powder motors with over 62.5g propellant are still regulated.

[shreadvector]

Please provide a link to support that claim.

I know that the CPSC has a 62.5 gram limit for Model Rocket Motors for those under 18 year of age. Just like reloadable motors, you need to be 18 or older for anything that exceeds that.

Check ATF regs. Black powder motors with over 62.5g propellant are still regulated.

[MarkII]

The most powerful G motor overall on the market now is a reload, the CTI Pro29 G125RL. It has a certified total impulse of 159.6 N-sec., which is about as close to a "full" G (100% G) as you can get. It does have an average thrust of greater than 80N, so it isn't a "model rocket motor" as defined by NFPA 1125. What is and what isn't a "mid-power motor" is a matter of personal definition, I suppose, since no such terminology appears in the NFPA codes. "Mid power" is a purely informal, unofficial descriptor that is used in our hobby but not in any regulations.

[KenRico]

Just curious while building my first 29mm motor mount rocket...what is the most powerful single use engine you can use without a L1 certification? Is it the AeroTech G80?j

Wow, alot of replies ! Took me a lot of time to figure out why I could buy a G reload for under $10, but F's require $27 hazmat.

If I am buying a single use motor onsite like a AT G80 Blue Thunder, and they don't happen to have the delay I need the others Redline, Mojave Green are very close in performance. For something different the Metalstorm is coming in a G75 single use .

If you have access to a Hobbyline RMS 29 40/120 case the Mojave Greens reloads are inexpensive and there is a G138T Blue Thunder that I can't wait to fly but it does require L1 .

Nice CC Express thread, what did you have in mind for a 29mm MMT rocket ?

Kenny

[cjl]

If you have access to a Hobbyline RMS 29 40/120 case the Mojave Greens reloads are inexpensive and there is a G138T Blue Thunder that I can't wait to fly but it does require L1 .

That's an excellent motor - tons of push for a G, and not a bad flame either. I would definitely recommend it.

[KevinDunn]

Please provide a link to support that claim.

27 CFR 555.141(a)(10)

The walton ruling vacated atf regulation of apcp motors, but left black powder in the domain of atf. This doesn't have anything to do, however, with whether a motor is certified HP or not. It has to do with whether you need a LEUP from the atf to possess black powder motors.

[KevinDunn]

The most powerful G motor overall on the market now is a reload, the CTI Pro29 G125RL. It has a certified total impulse of 159.6 N-sec.

G54RL is very close to that, with total impulse 159.1 N-sec, but because of the low average thrust, is not designated HP.

[Green Jello]

Nice CC Express thread, what did you have in mind for a 29mm MMT rocket ?

I'm not really sure yet. I just bought a 30" body tube, the motor mount parts and a nice ogive nose cone. I'll start this one after I'm done with the CC Express.

[shreadvector]

Exactly.

27 CFR 555.141(a)(10)

The walton ruling vacated atf regulation of apcp motors, but left black powder in the domain of atf. This doesn't have anything to do, however, with whether a motor is certified HP or not. It has to do with whether you need a LEUP from the atf to possess black powder motors.

[MarkII]

G54RL is very close to that, with total impulse 159.1 N-sec, but because of the low average thrust, is not designated HP.

Good point; you are right. I had only looked at total impulse, so I missed that one's distinction. It means that the G54RL is the most powerful model rocket G motor overall, which is relevant because G motors not classified as HP are what we are talking about here.

[BobH48]

For something different the Metalstorm is coming in a G75 single use .

Kenny

I thought all "Sparky" motors were still considered HPR or has something changed?

[KevinDunn]

From the Combined Motor List: (HP) G75M-4,7,10
(HP) means high-power

[Green Jello]

Open Rocket lists an AeroTech G55-15 in it's list of 24mm engines. I can't find it on the NAR site. Is this a real engine?

Edit: Oh...looks like it was decertified

http://www.thrustcurve.org/motorsearch.jsp?id=91

[MarkII]

Open Rocket lists an AeroTech G55-15 in it's list of 24mm engines. I can't find it on the NAR site. Is this a real engine?

Edit: Oh...looks like it was decertified

http://www.thrustcurve.org/motorsearch.jsp?id=91

There are obsolete motors sprinkled throughout many databases that we use. They remain in them for historical reference purposes, I suppose. If you are like me and enjoy occasionally delving into the history of this hobby, then that's a good thing. The latest Combined Reference List can tell you what is currently kosher.

http://www.nar.org/SandT/pdf/Combine...sByImpulse.pdf

[bobkrech]

Open Rocket lists an AeroTech G55-15 in it's list of 24mm engines. I can't find it on the NAR site. Is this a real engine?

Edit: Oh...looks like it was decertified

http://www.thrustcurve.org/motorsearch.jsp?id=91

Rocketvision made a bunch of small high performance rockets. http://www.rocketreviews.com/manufacturer-6400.html

They had AT private label their motors: the F72 and G55, both high thrust 24 mm SU motors.

Their Machbuster would apogee at ~5000' and was hard to find after it landed.

The motors were made by Aerotech before the fire, and never went back into production, probably because Rocketvision went out of business, and AT changed their casing design.

Bob

[luke strawwalker]

I thought all "Sparky" motors were still considered HPR or has something changed?

Yes I think this is correct, but stand to be corrected if not... I think that's the case due to the special precautions required when launching them...

later! OL JR

[Coop]

I admit: I find some of the MPR L1 requirements just goofy. 24 and 29mm F and G's requiring L1, to me, just makes no sense.


Later!

--Coop