How heavy is the biggest HPR?

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Well-Known Member
Feb 5, 2009
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How heavy is the largest high power rocket? And what one was the biggest?

The largest I know of and remember was the Bigger Dawg launched by a couple friends in NC. It made the cover of one of the Magazines and weighed in at 562 lbs, I think. 24" diameter, but not real long as it was an upscale.

On this KCAR poster I have, there was something called "Project 439". It was 43 feet long and weighed 1200 pounds.
So if mine comes in at 100 lbs. or so that is not too much then I'd guess.

wow, quite a jump, mid power to 100lb. beasts!

It's still significantly sized, the larger stuff is pretty insane.
100 lbs isnt too bad, would take a mighty big motor though thats for sure

that is quite the jump!
Motors, schmotors! Who needs motors anyway? Well I guess I do. But I won't need it until 10,000 feet or so... and then I am looking for a big push, a 75mm or 98mm.

Now see here guys!

If you have to have heavy equipment to load it onto the launch rail that's getting too big for me...

Let me know where I do wanna watch!


With the 5 to 1 ratio, even the largest L motor isn't going to do it for you. You are looking at a whopper of a L3 motor...

Good luck!
So, for us non-level type guys - aka - me, is there a chart somewhere that easily shows what the High power motor can lift ?

Yeah, I do need to bone up on my newtons and all, but sometimes, I like easy explanations. 8)
to lift a 100lb rocket, your gonna need an L3 motor, gotta love those L3 motors:)
Yeah, I do need to bone up on my newtons and all, but sometimes, I like easy explanations. 8)

Here's a qucik answer for a pretty good idea on what a motor will lift:

Take the average thrust and divide by 4.45. That'll tell you the average pounds of thrust the motor delivers. Then divide that by 5 to get the 5:1 safety margin that seems to be considered the standard in rocketry. I think you can fudge a bit on the 5:1 depending on the rocket and the wind but shoot for the 5:1 as a minimum.

For example:

An AT M1315 motor:

1315/4.45 = 295.5 lbs. of thrust average. Divide that by 5 = 59.1. So, a 59 lb rocket (loaded with motor) has a 5:1 ratio for that motor.

Or, the easiest to figure a Pro54 K445 = 445/4.45 = 100/5 = 20 lb loaded rocket for a safe liftoff.

This is a good starting point, especially on neutral a burn motor. However, it may be better to take a look at the actual thrust curve to see the initial thrust of the motor.

before you do that Iw ould go to thrust curves and look up the actual designation of the motor, for some reason manufatures change the designations

for example

an M1939 is actually an N1691


The easiest way to estimate the lifting power of a motor, or the minimum size motor needed to lift an airframe, is to divide the average thrust in Newtons by 25 or multiply the weight of the rocket in pounds by 25.

So an M1939 will be able to safely lift an airframe weighing :

1939 / 25 = 77.6 pounds

Or to safely fly a 100 pound rocket you would need a motor(s):

100 * 25 = 2500 Newtons averge thrust

So the 100 pound rocket reference earlier will need at least a M2400 motor or two or more motors with a total average thrust of 2500 Newtons or greater.

The above is not an exact method of calculating weight and thrust proportions, but it is an easy method of doing a "reality check" on motor selection. I use it when I'm RSOing to make sure that the motor selected by the flyer has enough thrust to get his rocket off the pad safely.

Ken Holloway
I never said it was getting off the ground using a rocket motor... only at 10,000 feet or so. It should already be travelling 70 mph or so when the rocket motor fires.


The Gate's Saturn 1B is looking like it will weigh anywhere from 1200-1500 pounds when loaded to the max.

Then when they get to the Saturn V, well, you do the math..:D
I am unifing these threads about my HPR project. look for "RMX-1"

Just wanted to say thank you to all whom responded in regards to motor thrust and weight issues. I've got some reading to do. 8)

Dang, this place is great !
Wow, I dont quite understand how that thing works, but it looks BRILLIANT!

What will it do? :eek: :eek: :eek: :eek: :eek: :eek:
Originally posted by shrox
How heavy is the largest high power rocket? And what one was the biggest?


It was 102 meters tall, 10.06 meters in diameter, weighed 3,038,500 kg, and was a 3 stage cluster model. The first stage burned five W class motors rated at 6,747,580 newtons each. It cost $431 million to launch, in 1967 dollars.

Since HPR wasn't well standardized at the time, the engines were incorrectly labeled as F-1's.
A model made of gleaming white metal 363 feet tall? I think it was operational, and now sleeps in the grass at Johnson Space Center.

Hey... That rings a bell... I think it was called the Saturn or something...
Hunstville, AL boasts to be the home of the worlds largest model rocket ever built. A full scale Saturn V...

The future plans will be to build a full scale launch pad and gantry, complete with restaurant at the top.