Motor Design Requirements
Desired initial thrust is 6000 to 8000 pounds
Total Impulse 100,000 NS to 125,000 NS
Chamber pressure is expected to be between 600 and 800 PSI
Propellant must be pourable.

Room temperature curing is preferred.
Long working time is preferred
Cure time before firing is of no concern.
Propellant must have a demonstrated large margin for error.

Port area to nozzle area ratio can not be less that 1.75; a ratio of 2.0 or above is preferred
Mass Flux should be less than 1.75; will accept 1.75 < Mass Flux < 2.50 for no more than 750 milliseconds after startup.

A case bonded finocyl motor with an ID of 7.5
Motor Length is up to the designer; Length of 72" +/- 18" is expected

A flame color is of no concern, motor performance will be the driving criteria.  A flat motor curve is expected.  Motor curves that show an initial progressive curve to allow for any erosive burning at motor ignition will be part of the design.

Motor Development Scheme
Traditional Development: 8" motors and 12" motors would be developed individually.  This would involve several test burns for each motor size.  Assuming 4 burns to get this dialed in would require 4 X 125 pounds for the 8" motor, and 4 X 525 for the 12" motor.  This would equal 2600 pounds of propellant to be burned before the flight.  Te cost of this is outside the budget.....even if we had a budget at this point.  Motors will be developed based on the assumption that motor performance is scalable.  The 8" motor design will be the central point.  The 8" design will be scaled up and down for this project.

The following phased gate approach will be used for motor development.

6" Motor Testing and evaluation

First Burn:  Motor should not CATO; performance should be within 30% of predicted.  Extensive analysis will be performed to determine why actual performance did align with predicted.  Thrust, chamber pressure,  grain geometry and erosive burn will all be evaluated.  Wholesale changes will be applied to the second test burn.  Process and procedures will be accurate recorded, defined, and applied.

Second Burn:  This should be the dialed in burn.  Changes derived from the first burn will be applied.  Small changes will be allowed; but performance should be very close to predicted. 

Pre-production Burn: Performance deviation must be within 5% of predicted.  Motor must perform as predicted.  Motor design will be frozen at this  point.  No improvements will be allowed from this point  forward.  Processing, and procedures will be frozen at this point.

8" Motor Testing and evaluation

First Burn:  All motor design elements from the 6" testing will be applied to the 8" test.  Any deviation from predicted performance will be attributed to scaling, and adjustments made.  Only those deviations from the 6" test will be addressed, and applied. No other changes will be allowed.

Pre-flight Motor: Performance must be as predicted. Deviations from predicted, will be tolerated provided the root cause can be identified. 

Flight Motors: Four 8" motors will be produced duplicating all the pre-flight motor. 

12" Motor Testing and evaluation

All data obtained from the 8" testing will be applied to the 12" motor.  The 12" motor will be produced directly from data obtained from previous burns.

Propellant

Several propellant formulations are currently under investigation. 

AlumaFlame: Is the clear front runner at this time.  AlumaFlame is TeamNumb's standard propellant.  Alex McLaughlin came up with it years ago.

Amarillo Blue: Initial BurnSim results show this propellant to have a higher than desired burn rate. 

Unknown Blue:  This propellant used by Dave Leininger in Locomotive Breath looks great in flight, no data is available to perform an evaluation at this time.

White Lightning (clone), and Wayside White seem to have potential but more data is needed.

Any clones of Warp9, Kosdon Fast, or V-Max type propellants would be awesome, but will not be considered as they are deemed to aggressive,

Current Burnsim Design

Four Booster Motors 8" Q-20644 (Code Name: The Fantastic Four)

One Sustainer Motor 12" S-54100 (Code Name: Hammer of the Gods)

Burnsim data files

What is BurnSim?

BurnSim is a solid rocket steady-state ballistic simulation software package for the Windows platform. In a nutshell, input your motor, nozzle and propellant characteristics and BurnSim calculates the Kn through the burn and predicts estimated chamber pressure and motor performance. Once your motor design is in BurnSim, you can tweak the parameters such as nozzle diameter or grain core diameter and instantly see how the Kn, chamber pressure, and motor thrust is affected. BurnSim will also optimize your nozzle design.