• Cycle 2 Baseline (clipped delta with cycle 2 masses etc)

  • This is the cycle 2 masses and lengthes and such with the fins from last year as a starting place

• Cycle 2 sim 1 (first stab at fin size for 2.5 calibers)

  • This is a rough simulation Joel did to get a sense for what the flight paramters looked like before he messed with stuff a lot

  • Ended up just shortening the fins a hair to 6in.

Wind Design Condition Studies

• Methodology:

  • Set fin size to get lowest stability 2.5 at wind condition

  • Check flutter and increase fin thickness to level where flutter FOS is greater than 1.5 using increments of increasing fin thickness by one 2x2 twill on spreadsheet https://docs.google.com/spreadsheets/d/1bED5_mtsKTZOK_8UIh9m1AtHdDWtagWdZMeCRRHz9sw/edit#gid=1882516631

  • Enter new thickness in OR ignoring mass change and check stability still same.

  • get all numbers required and enter here: https://docs.google.com/spreadsheets/d/1IiWsDT2IP_I34qDOhQQSvvtqstiJyr9cIYkMXxRI6Vc/edit#gid=0

• This is to help us decide what wind speed we want to design to

  • Cycle 2 Wind Sim 8mph

    • Designed fins to have min stability of 2.5 calibers at 8mph launch condition

    • Same as Cycle 2 sim 1 (first stab at fin size for 2.5 calibers)

  • Cycle 2 Wind Sim 10mph

    • Designed fins to have min stability of 2.5 calibers at 10mph launch condition

  • Cycle 2 Wind Sim 12.5mph

    • Designed fins to have min stability of 2.5 calibers at 12.5mph launch condition

  • Cycle 2 Wind Sim 15mph

    • Designed fins to have min stability of 2.5 calibers at 15mph launch condition

Fin Shape Testing:

Methodology: As there are too many variables to independently tweak by hand all at once and simulate the outcome of each option now that we/Joel has a basic grasp on how stable the rocket is and how different changes to the fins affect the results he will design a fin shape and then run it through a series of simulations to see if the performance of the fin is up to our desired results. If this does not result in an effective fin or Joel thinks there is performance left on the table he will repeat the process. Fin shapes are designed for 2.5 cals of stability at 9mph wind case with FOS on flutter of 1.5

• Characteristics to be measured:

  • Apogee, lowest stability prior to apogee (>5secs before apogee), lowest stability, highest stability, max velocity,

Tests to be run:

1. Expected Mass and length:

   1. expected wind, pressure, temperature

   2. 15mph wind with whatever is worse 85th percentile pressure and temperature

   3. 0mph wind with whatever is worse 85th percentile pressure and temperature

   4. Improved surface finish with expected wind, pressure and temperature

2. Max Mass Condition:

   1. expected wind, pressure, temperature

   2. 15mph wind with whatever is worse 85th percentile pressure and temperature

   3. 0mph wind with whatever is worse 85th percentile pressure and temperature

   4. Improved surface finish with expected wind, pressure and temperature

3. Min Mass Condition:

   1. expected wind, pressure, temperature

   2. 15mph wind with whatever is worse 85th percentile pressure and temperature

   3. 0mph wind with whatever is worse 85th percentile pressure and temperature

   4. Improved surface finish with expected wind, pressure and temperature

Shape “KOTS 2.0“:

• Start with the KOTS shape and increase height until stability is correct and then mess with flutter/thickness after

Shape “Tip“:

• Idea is to start with a KOTS fin and moderately increase the tip chord is the hopes of finding a way to increase the flutter velocity without much increase in thickness. Likely will also require a height increase of the fin.

Shape “Tip with Sweep“:

• Start with the tip concept and then add a sweep to move the fin CP effect back more in hopes that height can decrease and therefore thickness can decrease.

• Analyzed without changing the weight and appeared to be the best option however upon doing a weight study found roughly 2.3in^2 increase in area and plate stock is 0.277lbs/in^2 for 3/16 thick meaning adding 0.637lbs in plate stock. Because of our own added material rounded up to 1.25lbs. dropped apogee for 1a case to 28557 which is significantly worse but still better than all other shapes. However lowered stability to 2.3 roughly meaning a size increase which would reduce flutter meaning a thickness increase and even more weight. This will for sure reduce apogee down to similar levels as KOTS 2.0 design. therefore shape was determined against.

If extra time:

Shape “Playing with Fire“:

• Design to have closer to 2 cals of stability at 9mph and really work on getting the apogee up even with some risk.

Sensitivity studies on:

• Other OR sim inputs

• Fin shape with flutter considered

  • Think we should increase the fin tip chord slightly probs like 1 inch after weather thing is done.

• Increasing fin thickness vs area for flutter resistance

  • It appears that changing fin area does not affect flutter FOS nearly as much as changing fin thickness so thickness changes will be used for weather studies.

• Launch rail being shorter if want

• Surface roughness improvement

• Ran study on file with cycle 2 masses not quite fully done and apogee went from 29413ft to 31347ft changing from regular paint (2.36mil) to smooth paint (0.787mil). No noticeable impact on stability

• Weight increase due to larger fin area on tip swept back shape

  • Analyzed and found roughly 2.3in^2 increase in area and plate stock is 0.277lbs/in^2 for 3/16 thick meaning adding 0.637lbs in plate stock. Because of our own added material rounded up to 1.25lbs. dropped apogee for 1a case to 28557 which is significantly worse but still better than all other shapes