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Well-Known Member
Jan 18, 2009
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What would it be if I clustered two elis mountain G-35's Would it be an H or a G-70 I dont know I just woke up and my brain isnt working yet I need coffee
When you cluster (and get them all to ignite) you add the total impulse to get the combined total impulse and then you add the average thrust to get the combined average thrust.

Look up the total impulse and since you have 2 of them, multiply by 2. Take that number and look it up on the total impulse scale for the various letter classes of motors.

2 times 35 is 70, so the average thrust would be 70 newtons.

Originally posted by Bowhunter
What would it be if I clustered two elis mountain G-35's Would it be an H or a G-70 I dont know I just woke up and my brain isnt working yet I need coffee
That is why I just bought a Loc/Precision Tri-Star.
3 G's BABY!!!
according to the NAR Model Rocket Safety Code 2 G35 would still be considered a Model Rocket:


Size. My model rocket will not weigh more than 1,500 grams (53 ounces) at liftoff and will not contain more than 125 grams (4.4 ounces) of propellant or 320 N-sec (71.9 pound-seconds) of total impulse. If my model rocket weighs more than one pound (453 grams) at liftoff or has more than four ounces (113 grams) of propellant, I will check and comply with Federal Aviation Administration regulations before flying.

If the total WEIGHT <= 1500 GRAMS (3.3 LBS) AND the 2 G35 contain less than 125 g total propellant(which they do) then it is considered a Large Model Rocket(LMR) , NOT a HPR.... 3 G35 would make it a HPR.....

Since it would be considered a LMR you would have to do the following per the FAA:

Large Model Rockets - Notification Required
Per NFPA and FAR regulations, large model rockets weigh 1 to 3.3 pounds (454 to 1500 grams) at launch
and contain less than 125 grams of total fuel. Model rockets which weigh less than one (1) pound at
launch but which contain between 113 and 125 grams of total fuel also fall under this classification. Some
“H” engines contain less than 125 grams of fuel, however, you need at least a level one high power
certification from NAR or TRA to purchase and use H motors. In accordance with the safety codes, these
rockets must use only pre-manufactured, solid propellant motors, and do not use metal body tubes, nose
cones or fins.
When launching rockets which fall within this definition, FAA regulations require that the nearest Air Traffic
Control center (ATC) and any airports within five nautical miles be notified of the launch between 24 and
48 hours prior to the launch. This is notification and not permission. Phone numbers for FAA ATC’s may
be found in the Transportation/FAA section of the white pages under the Federal Government listings.
When notifying the FAA, provide the following information.
Notice of Large Model Rocket Launch - FAR 101.22
Pursuant to the requirements set down in Federal Aviation Regulation 101.22, this is a notice of a launch
event for Large Model Rockets. For your information, a Large Model Rocket is defined as a model that
uses not more than 125 grams of propellant, made of paper, wood, or breakable plastic, containing no
substantial metal parts, and weighing not more than 1,500 grams including propellant. A model rocket,
exempt from regulation as per FAR 101, Subpart C, is identical in definition except that its maximum
weight is 453 grams and its maximum propellant weight is 113 grams. The following information is
specifically required by this regulation:
Name, address, and telephone number of Launch Coordinator:
Location of Launch Site:
Date and Time of Launch Operation:
Estimated Number of Rockets to be Operated:
Estimated Size and Weight:
Estimated Maximum Altitude:
As per the requirements of FAR 101.23, this launch event will be cancelled if the horizontal visibility is less
than five miles or if the sky is more than five-tenths obscured at the maximum estimated altitude. In
addition, if surface winds exceed a steady 20 miles per hour, this launch event will also be cancelled for
safety reasons.
Page 2
This notice, or equivalent information via telephone, is being provided to the FAA and to all known airports
within a 5 nautical mile radius of the above-named launch location.

The NAR Pinkbook ONLY applies to NAR Competition......
I'm crossing threads here, but, I did figure my Tri-Star with three G's would qualify as high-power by definition and not JUST a "mid-power cluster".
correct nomopbo.... 3 G's would be over the 113/125 gram total propellant limit and probably over the 320NS limit as well.....
Tri-Star rocks on 3xG35s but actually I liked flying it on 3xF20-7s instead - the flames were longer.

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