Quantcast

5:1 Thrust to weight ratio

The Rocketry Forum

Help Support The Rocketry Forum:

AfterBurners

Well-Known Member
Joined
May 8, 2012
Messages
7,465
Reaction score
335
Location
Dallas Texas
I completely understand this method and calculations, but when they state the following:

"The average thrust of a motor should be at least five times the total weight of the fully loaded rocket"

Just needed some clarification on "Fully Loaded Rocket" as in with the motor loaded or without? I'm assuming with it loaded?

Then you make your calculations based on that weight
 

bobkrech

Well-Known Member
Joined
Jan 20, 2009
Messages
8,351
Reaction score
28
Yes the pad weight is with the motor loaded.
 

markkoelsch

Well-Known Member
Joined
Mar 18, 2009
Messages
4,300
Reaction score
148
I completely understand this method and calculations, but when they state the following:

"The average thrust of a motor should be at least five times the total weight of the fully loaded rocket"

Just needed some clarification on "Fully Loaded Rocket" as in with the motor loaded or without? I'm assuming with it loaded?

Then you make your calculations based on that weight
Fully loaded ready to fly.
 

dhbarr

Amateur Professional
Joined
Jan 30, 2016
Messages
6,500
Reaction score
1,119
Don't add the weight of the igniter; everything else counts :)
 

FredA

Well-Known Member
Joined
Jan 19, 2009
Messages
2,072
Reaction score
284
For a rough guide with a "normal" Bates grain motor, take the number part of the motor designation and divide by 25 and that should be equal to or larger than the pad weight in pounds.
 
Top