RMS thrust curves

[ben]

I am wanting to do some RMS clusters but don't know if I have to use all RMS motors or can use a combination of SU and RMS motors. I also want to know how to calculate the number amount of thrust so I can make a big 29mm cluster or 24mm cluster and know if I am under L1 or if I am over?

thanx,

 

[OKTurbo]

Hey ben,

Try this..
https://www.info-central.org/propulsion_motortotal.shtml

 

[bobkrech]

Originally posted by ben
I am wanting to do some RMS clusters but don't know if I have to use all RMS motors or can use a combination of SU and RMS motors. I also want to know how to calculate the number amount of thrust so I can make a big 29mm cluster or 24mm cluster and know if I am under L1 or if I am over?

thanx,

Single motor thrust is restricted to 80 Newtons, but total installed thrust is not restricted, however total installed impulse and total installed propellant weight is.

Mostly from https://nar.org/hpcert/NARhpdetails.html

A person needs high power certification if he:

Launches models containing multiple motors with a total installed impulse > 320 Newton-seconds, or

Launches models containing a single motor with a total installed impulse > 160 Newton-seconds, or

Launches rockets that weigh more than 53 ounces (1500 grams), and/or contains more than 125 grams of propellant in total, or

Launches models powered by rocket motors not classified as model rocket motors per NFPA 1122, e.g.: Total Impulse in excess of 160 Newton-Seconds, Average thrust in excess of 80.0 Newtons, or containing > 2.2 ounces (62.5 grams) of propellant.

G-Hybrid rocket motors are not allowed for folks under 18.

Bob

 

[ben]

thanx for the infoe I like that thrust finder thing the cluster I want to launch will be 4 E30 29mm with a 38mm G55 I am under the limit I have 285 N seconds of thrust just passed (yes!!!!)

thanx,

 

[cjl]

Small problem - with that cluster, you're over 125g propellant mass - you have almost 140g.

 

[Rocketjunkie]

Originally posted by cjl
Small problem - with that cluster, you're over 125g propellant mass - you have almost 140g.

So he needs a waiver. Otherwise, he can still fly it.

 

[bobkrech]

Originally posted by Rocketjunkie
So he needs a waiver. Otherwise, he can still fly it.

Yes. Flying the rocket requires a formal written FAA waiver.

No. Since he is a minor he can not legally get a waiver and fly the rocket on his own. If he is L1 Jr. certified he can fly it at a waivered NAR launch with a sponsor. Since he is a minor, he can not legally have a G motor, or high power motor in his possession.

Bob Krech

 

[ben]

I am aware of the FAA waiver my club has a 5,000 goot waiver my dad is the one helping me access these motors I am curently working on this cluster for this rocket....

https://www.rocketryforum.com/showthread.php?s=&threadid=20964


I will use that one to cert on with a 38mm center and 4 29mm outboards. I am working on a half scale version to fly on my own with 3 29mm F40's and such thank you for your help and concerne