sugarshot
Electrical
- May 26, 2006
- 24
Background;
Of the Sugar Shot to Space project (see sugarshot.org) which is an amateur project expected to fly to 67 miles altitude, we (the Payload Team and our outside analysts) are attempting to apply some analysis for the sake of predicting the flight path 'on the fly', and analytically, as a prediction. To this end, I seek your help in coming up with a justifiable (proof-worthy) approach to the problem.
The rocket;
Vertically-bound rocket flight, 27 feet tall, 1100 lbs,
(900 lbs solid fuel) with no guidance whatsoever except fixed fin-induced rotation attempting 4 turns per second.
Due to the consumption of fuel, the center of gravity will move forward for 9 seconds, remain constant for a short period, then move aft-wards - all the while the vehicle configuration does not change (no parts are dropped) but the wieght of the fuel is given up, of course. Hypersonic
flight (mach 5+) is expected briefly.
The problem;
We (myself as payload team lead, and the outside analysts) take it that a vertically-bound rocket flight, with no guidance whatsoever except fixed fin-induced rotation (roll - but we call it spin), would upon liftoff be pointed 'perfectly' vertically, yet have the tendency to fly along a roughly 'parabolic' path.
What we need is a way to predict what would be normal or expected for this parabola.
Presently we have three different possible ways of viewing the problem.
A
My personal favorite is the simple view.. that the wind will be blowing say 4 miles per hour (of course its not constant), and this will cause the flight axis to veer from vertical and is not so hard to calculate - based on fairly simple physics. So 'prediction' involves knowing
what winds to expect at altitudes for the unknown launch location.
B Another view is that even if launched vertically in still air, the flight path will be predictably parabolic. But I differ.. in the next, C..
C Like 'B' above, with the same moving 'center of gravity' and stationary 'center of pressure', even with no wind the parabolic flight path would be a matter of statistical distributions of possible flight paths, with a most likely path (with the highest probability of occurance).
For myself, I want foremost to get it right, but also to convince the guys who want to use the 'B' approach that it's not possible, and that 'C' is too messy, and that 'A'
is most likely arguably true as it 'stands to reason'.
So it's your turn.. please advise us on what approach makes the most sense. One of our goals is to convince the FAA that we know exactly what to expect for possible flight paths, and particularly what window we can operate in without terminating the flight.
To reiterate, the problem is one of, for a solid fuel rocket, launched vertically, what 'parabolic' flight path could be calculated on what basis?
I know this is a 'sketchy' problem, all the more reason to ask you guys.. so thanks much for reading, I look forward to your insights and feedback.
Geoff
Of the Sugar Shot to Space project (see sugarshot.org) which is an amateur project expected to fly to 67 miles altitude, we (the Payload Team and our outside analysts) are attempting to apply some analysis for the sake of predicting the flight path 'on the fly', and analytically, as a prediction. To this end, I seek your help in coming up with a justifiable (proof-worthy) approach to the problem.
The rocket;
Vertically-bound rocket flight, 27 feet tall, 1100 lbs,
(900 lbs solid fuel) with no guidance whatsoever except fixed fin-induced rotation attempting 4 turns per second.
Due to the consumption of fuel, the center of gravity will move forward for 9 seconds, remain constant for a short period, then move aft-wards - all the while the vehicle configuration does not change (no parts are dropped) but the wieght of the fuel is given up, of course. Hypersonic
flight (mach 5+) is expected briefly.
The problem;
We (myself as payload team lead, and the outside analysts) take it that a vertically-bound rocket flight, with no guidance whatsoever except fixed fin-induced rotation (roll - but we call it spin), would upon liftoff be pointed 'perfectly' vertically, yet have the tendency to fly along a roughly 'parabolic' path.
What we need is a way to predict what would be normal or expected for this parabola.
Presently we have three different possible ways of viewing the problem.
A
My personal favorite is the simple view.. that the wind will be blowing say 4 miles per hour (of course its not constant), and this will cause the flight axis to veer from vertical and is not so hard to calculate - based on fairly simple physics. So 'prediction' involves knowing what winds to expect at altitudes for the unknown launch location.
B
Another view is that even if launched vertically in still air, the flight path will be predictably parabolic. But I differ.. in the next, C..C
Like 'B' above, with the same moving 'center of gravity' and stationary 'center of pressure', even with no wind the parabolic flight path would be a matter of statistical distributions of possible flight paths, with a most likely path (with the highest probability of occurance).For myself, I want foremost to get it right, but also to convince the guys who want to use the 'B' approach that it's not possible, and that 'C' is too messy, and that 'A'
is most likely arguably true as it 'stands to reason'.
So it's your turn.. please advise us on what approach makes the most sense. One of our goals is to convince the FAA that we know exactly what to expect for possible flight paths, and particularly what window we can operate in without terminating the flight.
To reiterate, the problem is one of, for a solid fuel rocket, launched vertically, what 'parabolic' flight path could be calculated on what basis?
I know this is a 'sketchy' problem, all the more reason to ask you guys.. so thanks much for reading, I look forward to your insights and feedback.
Geoff
