Comanche-3: LPR or MPR?

[Kirk G]

Just a quick question.

Is the Comanche-3 considered a Low Power Rocket, or a Medium Power Rocket...because of the D12-0 booster that is required for the lowest 3rd stage?

I'm assuming it's still LPR on general principle, but would like to hear the thinking either way.

Also, for those of you who have flown it before, what's the best or recommended combinations of motors for 2 stage or 3 stage operation?
Does it vary by weight of the boosters?

Thanks.

 

[rharshberger]

DOH!

It's all over now. It was a nice ride while it lasted...

The king is back.

Its LPR

 

[Trident]

Just a quick question.

Is the Comanche-3 considered a Low Power Rocket, or a Medium Power Rocket...because of the D12-0 booster that is required for the 3rd stage?

I'm assuming it's still LPR on general principle, but would like to hear the thinking either way.

Also, for those of you who have flow it before, what's the best or recommended combinations of motors for 2 stage or 3 stage operation?
Does it vary by weight of the boosters?

Thanks.

If you are still talking about the Comanche, look at the Estes website for recommended motors. This of course makes sense for any staged kit. Go by what the manufacturer recommends.

 

[Daddyisabar]

2 stage D12 0 to C6 7 is almost as high as loaded for BEAR: D12-C6-C6-7! It all depends on field and weather conditions. I get the good eyes team together and go for it. Recover all three stages more often then not. A nice mylar steamer really helps. Small reflective decals on second stage painted florescent orange.

Some even start with an E12-0. Heck they just hollow it out and go 24mm all the way. Dats loadin' fer GRIZ!

 

[Woody's Workshop]

Estes Engines are all BP (black powder), [correct me if I'm wrong someone], but that makes it low power.

 

[les]

Estes Engines are all BP (black powder), [correct me if I'm wrong someone], but that makes it low power.

I don't think the propellant type dictates if it is LPR or not. I would still consider an AT D10 as LPR

I thought E or lower was LPR
F/G was MPR
H and higher as HPR

Perhaps one could argue whether E is LPR or MPR....

And do you consider the AT engines re-branded as Estes as an Estes engine?

 

[rharshberger]

Estes Engines are all BP (black powder), [correct me if I'm wrong someone], but that makes it low power.

For the most part correct, Estes manufactured motors are all BP, but E, F, G motors are MPR and Estes makes E and F BP motors. Estes does sell rebranded Aerotech composite MPR motors.

 

[Daddyisabar]

It is all about propellant weight and the magic 125 gram cut off. Three E9's in a Richter Recker is fun and safe for the kids. Two G64s going off on copperheads in your Sherri's Hot Rockets Gemini Titan is great family fun in the park. Two E9's and an F15, HOLD THE PHONE! High Power Danger! Certification and FAA waiver required! 125.1 grams of nasty black powder propellant is simply way too dangerous!

For LPR - MPR just look at TRF guidelines, D and below is LPR. So when I bring my Comanche 3 up to the RSO line I say "She is loaded for bear and I am flying awesome MID POWER!" A mighty D12 and two fully packed C6 motors is like a super long burn E9 equivalent, definitely not Low Power for the kids! Altitude junkie Mid Power it is! Even a Comanche 3 two stage on a mighty D12 and an A8 5 is awesome Mid Power! That blows simple low power D's away and puts you firmly in the realm of staged Mid Power and much more manly pursuits.

After swearing and cursing while loading up the difficult 18mm composite in the skill level 5 Zooch kit. After reading the directions many times, much grease on the fingers, getting that tight paper casing in just perfect, using the lowest setting on the wrench to skillfully tighten the rear closure. Having spent much more time, effort, sweat and anxiety than the time I loaded up that Level One certification motor under strict supervision. I walk up proudly displaying the RMS D21 and am told to go to the LOW POWER kiddie rack, going to launch it with the Cub Scouts.

 

[rocketgeek101]

Just a quick question.

Is the Comanche-3 considered a Low Power Rocket, or a Medium Power Rocket...because of the D12-0 booster that is required for the 3rd stage?

I'm assuming it's still LPR on general principle, but would like to hear the thinking either way.

Also, for those of you who have flow it before, what's the best or recommended combinations of motors for 2 stage or 3 stage operation?
Does it vary by weight of the boosters?

Thanks.

It's a question with no clear answer - as there isn't even a clear consensus on where LPR ends and MPR begins; unlike the clear division between MPR and HPR. Personally, I'd consider it LPR, but technically when flown with all it's stages it should probably be considered MPR. Either way, it doesn't matter as the rules for LPR/MPR are the same.

 

[watermelonman]

It's a question with no clear answer - as there isn't even a clear consensus on where LPR ends and MPR begins; unlike the clear division between MPR and HPR. Personally, I'd consider it LPR, but technically when flown with all it's stages it should probably be considered MPR. Either way, it doesn't matter as the rules for LPR/MPR are the same.

Personally I think G motors should move in with Hs and everything lower than that should be considered low power.

That is me, though.

 

[Daddyisabar]

I don't think the propellant type dictates if it is LPR or not. I would still consider an AT D10 as LPR

I thought E or lower was LPR
F/G was MPR
H and higher as HPR

Perhaps one could argue whether E is LPR or MPR....

And do you consider the AT engines re-branded as Estes as an Estes engine?

A guy at the club was having trouble inserting his Estes 29mm SU G80 motor into the rocket until he peeled off the label exposing the old Aerotech one underneath. He DeEstesized it to make it work.

 

[Daddyisabar]

Personally I think G motors should move in with Hs and everything lower than that should be considered low power.

That is me, though.

That would be a nightmare for me. The SHR Gemini Titan I have been dreaming about on two G's needs to stay basically in the LPR category and off a 1/4 inch rod. G's are considered tiny motors at some launches I have been to, kinda like Micromax. Thinking little G motors power Large and Dangerous, High Powered Rocket Ships is like so 80's.

But don't call my staged Comanche 3 low power. It is a minimum diameter, mid powered monster! Outta sight and Dynamite!

 

[rharshberger]

That would be a nightmare for me. The SHR Gemini Titan I have been dreaming about on two G's needs to stay basically in the LPR category and off a 1/4 inch rod. G's are considered tiny motors at some launches I have been to, kinda like Micromax. Thinking little G motors power Large and Dangerous, High Powered Rocket Ships is like so 80's.

But don't call my staged Comanche 3 low power. It is a minimum diameter, mid powered monster! Outta sight and Dynamite!

Amen, Reverend "outta sight, and Dino-mite".

 

[Daddyisabar]

Amen, Reverend "outta sight, and Dino-mite".

That is so 70's. Good Times! I just want to get out the old turtle neck, bell bottom pants, big peace symbol necklace and remember the times when the MIGHTY D RULED!

 

[Kirk G]

So it sounds like the motors would suggest LPR, but the experienced rocketeers want to classify the whole heavily loaded rocket as MPR due to height.
(I would have assumed A,B,C were LPR, and D,E were entering MPR...but that's just my limited experience.)

 

[Daddyisabar]

So it sounds like the motors would suggest LPR, but the experienced rocketeers want to classify the whole heavily loaded rocket as MPR due to height.
(I would have assumed A,B,C were LPR, and D,E were entering MPR...but that's just my limited experience.)

Think of it this way. When you stick that mighty D12-0 booster on it - IT THEN BECOMES MID POWER. Fly it C6-0 to C6-7 or lower and it is low power.

I saw one fly three stage on the smallest motors the guy could put into it. It was C11-0 to A8 -0 to A8-5. Staged right above the rod then puff, puff. Really cool and fun with LPR. That was loaded for squab!

 

[rocketgeek101]

Personally I think G motors should move in with Hs and everything lower than that should be considered low power.

That is me, though.

I disagree on your first point. I'd hate to see G's become regulated like Hs and up. I do agree though that it should just be LPR and HPR.

I'd like for A-G = LPR; H and up = HPR

 

[rharshberger]

I disagree on your first point. I'd hate to see G's become regulated like Hs and up. I do agree though that it should just be LPR and HPR.

I'd like for A-G = LPR; H and up = HPR

Some G's are already regulated, the AT G138 being one of them, they require L1 certification, I too think that there really should be two divisions.

Also according to NAR A-D impulse is LPR, E-G is MPR, and H and above is HPR. https://www.nar.org/standards-and-testing-committee/standard-motor-codes/

A Comanche-3 built and flown with the recommended motors would be an LPR as the largest motor is a D12 with has a total impulse of 16.8NS, total combined Newton Seconds for a max motor config is 34.4 total NS of thrust (D12, and two C6's). The max thrust is still just 16.8NS.

 

[watermelonman]

I disagree on your first point. I'd hate to see G's become regulated like Hs and up. I do agree though that it should just be LPR and HPR.

I'd like for A-G = LPR; H and up = HPR

They could be unregulated, or call it level zero and require something like ID and a signature. But I think G-H, I-J is a more sensible grouping than G, H-I, and then up.

 

[DizWolf]

I think we should unregulated the whole mess, personally.

 

[tab28682]

Technically, with a total impulse of 34.4 Ns using a D and 2 Cs, a Commanche -3 is a mid power rocket with an 86% E on board.

 

[rharshberger]

Technically, with a total impulse of 34.4 Ns using a D and 2 Cs, a Commanche -3 is a mid power rocket with an 86% E on board.

However can you still try and call it MPR when only one of the motors is lit at a time and the largest of those is 16ns max thrust, IMO just carrying the equivalent of an 86% E is not a MPR unless all three motors are burning simultaneously.

 

[jsdemar]

However can you still try and call it MPR when only one of the motors is lit at a time and the largest of those is 16ns max thrust, IMO just carrying the equivalent of an 86% E is not a MPR unless all three motors are burning simultaneously.

The impulse class of a rocket is based on the total impulse of all the motors installed, not just the ones lit on the pad. This includes all motors in a cluster and in the stages. It is coded in NFPA 1122 and 1127, which is the basis of both the NAR and TRA safety codes.

So, the full Comanche III is a "complex E". Min site dimension is 1000ft.

Two modroc G motors clustered or staged is a "complex H" but is considered a model rocket and not a HPR, as long as the total propellant weight is under 125g and none of the motors are >80N avg thrust (and not sparkies). Again, I'm not making this up, it's coded in NFPA 1122 and 1127, and therefore it's in the NAR and TRA safety codes.

Another example, for HPR, two I's in a cluster or staged rocket is a "complex J". It required L2 certification. And a 200ft safe distance.

 

[tab28682]

The impulse class of a rocket is based on the total impulse of all the motors installed, not just the ones lit on the pad. This includes all motors in a cluster and in the stages. It is coded in NFPA 1122 and 1127, which is the basis of both the NAR and TRA safety codes.

So, the full Comanche III is a "complex E". Min site dimension is 1000ft.

Two modroc G motors clustered or staged is a "complex H" but is considered a model rocket and not a HPR, as long as the total propellant weight is under 125g and none of the motors are >80N avg thrust (and not sparkies). Again, I'm not making this up, it's coded in NFPA 1122 and 1127, and therefore it's in the NAR and TRA safety codes.

Another example, for HPR, two I's in a cluster or staged rocket is a "complex J". It required L2 certification. And a 200ft safe distance.

Exactly.

 

[rharshberger]

Exactly.

I stand corrected, I disagree, but the law is the law.

 

[jsdemar]

I stand corrected, I disagree, but the law is the law.

On what basis do you disagree? The NFPA codes are based on the potential energy enclosed in the rocket, and the hazards that scale with the increase in impulse class. Some pretty smart people did the analysis that the codes are based on. After 25 years doing HPR, I can tell you that people significantly underestimate the increased risk of clustering and staging.

 

[tab28682]

In the big scheme of things, I do not thing it actually matters that much in any practical way that a Commache-3 is a mid power model in the "E" class, when loaded with a D and two Cs, or any other combo that puts the Ns at more than 20.

The site size does double from 500 to 1000 feet and the distance from people to the launch pad doubles from 15 to 30 feet. Really needs to be those distances for practical reasons, in any case.

 

[Kirk G]

Well guys, I get the drift that there's some disagreement here...

But I guess I've learned that I have two choices. Either D12-0, B6-0, B6-4 or D12-0, C6-0, C6-7 or something with that approximation.

In either case, I have a fixed field that I launch in, and I think that it dwarfs any 1000 ft measurements by at least a football field in all directions.

 

[bobkrech]

Model rockets must not weigh more than 1.5 kg. Model rocket motors have average thrust <= 80 N, iotal impulse <=160 Ns, and contain not more than 125 grams of propellant. NFPA 1122, 1125, NAR, TRA

Low power is up to and including D motor or LP >= 20 Ns total impulse. Low power rockets with total impulse not more than 20 Ns require a 15' separation distance and variable minimum launch site dimension depending on actual impulse. Mid power is E thru G motors 20 Ns < MP <= 160 Ns total impulse. Mid-power rockets with total installed impulse 20 < TI <= 160 require a 30 separation distance and minimum 1000' launch site dimension. Cluster rockets (2 Gs) with TI <=320 Ns but with not more than 125 grams of propellant require 100' separation distance and minimum 1500' launch site dimension. AllFPA 1122, 1125, NAR https://www.nar.org/wp-content/uploads/2014/08/MRSafetyCode.pdf

TRA Model Rockets require 30' separation distance. TRA https://www.tripoli.org/Portals/1/Documents/Safety Code/OPSC 2013 v1.0.pdf

Regulation is a technical term regarding control of explosives by BATFE. No APCP motors are regulated. Black power motors with not more than 62.5 grams of propellant are not regulated. Larger BP motors are BATFE regulated explosives and required a BAFTE explosives license.

APCP and BP Motors with a total impulse > 160 Ns and/or average thrust > 80 N and/or > 125 grams APCP/62.5 grams BP are high power motors which require NAR/TRA/CAR/UKRA high power certification to launch at NAR/TRA sanctioned launches. NFPA 1122, 1125, 1127, NAR, TRA

FAA does not care about total impulse, average thrust, or certification. Rockets with total propellant not more than 125 grams and not weighing more than 1.5 kg are Class 1 model rockets and do not require a FAA waiver. All other rockets require waivers. FAA Part 101 rules.

Bob

 

[jsdemar]

Well guys, I get the drift that there's some disagreement here...

But I guess I've learned that I have two choices. Either D12-0, B6-0, B6-4 or D12-0, C6-0, C6-7 or something with that approximation.

In either case, I have a fixed field that I launch in, and I think that it dwarfs any 1000 ft measurements by at least a football field in all directions.

No, not a disagreement, but incorrect assumptions about the safety code. I'm right, and so is Bob (blah blah blah). ;-)

Oh, and use a B6-6 in the top stage, not a B6-4. Longest delay is best or it will eject early and shread.