Medusa Characterization Motor Design
Responsible Engineers: Justin, Aimee, Tamara, Alex, Lee, Luke
Week 3 Assignments:
- Figure out nozzle ranges (in openmotor)- Justin
- Refining FC & nozzle design (dimensions)- Alex/Jeff
- Looking at o-rings for inner lip
- How to seal igniter - Tamara
- RTV the heck out of it??
- Firebolts?
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- Calculating yield strength in a thread/maximum load on a thread & cases with screw on forward closures - Alex My name jeff
- Screwed on forward closure done for small rockets
- Pretty viable
- Big tap/chonky threads
- Work with Cruz to figure out 3d experience - Aimee
- No emails yet
- Grabcad for now
- How thick does case need to be to reach pressure - Elizabeth
- Did calculations on case thickness
- Borderline on thin vs thick case so using both equations
- Choose the one that gives thicker case
- Around 2 inches OD
- Reach out to Kelly - Elizabeth
- Found yellow tubes on Mcmaster
- Need to find one that fits with the casting tube
- Find casting tube that fits in liner
- Integrated forward closure case design - Justin
- Used liner type that is same size as Kelly
- has been updated to remove steel ring
- Can do no forward closure design with tube machined in
- Bolt calcs
- Liner needs to be cut to size
- installation disk on one side
- End burner w/cylinder propellant for constant burn rate
- Air could get compressed
- Have steel bolt on bottom for venting
- Used liner type that is same size as Kelly
- Test stand - Aimee & Tamara
- Three prts
- Base plate
- weld to ring holding motor
- use aluminum plate to be able to weld
- Motor case
- Thick ring to hold motor
- hole in bottom
- Machine out half an inch to make a nub and thread it to screw on
- radial bolts that interface w motor
- if bottom fails what happens to top?
- have another ring on top that surround motor case
- top layer holding onto top of case
- hole in the center
- keep in place w/ eye bolts and ratchet straps
- Base plate
- Three prts
- Other
- 3 propellant formulas
- Boron
- 10 characterization fires
- Pressure Transducer
- hole drilled and threaded through side of motor
- sealed using teflon tape
- not threading phenalic, just hole for access
- 3 propellant formulas
Medusa Characterization Motor DesignWeek 1 Meeting Notes:
- New characterization motor design
- propellant casting tube & liner
- how to get around?
- 38mm or 54mm liner (contact Kelly)
- can make about 10 motors
- thicker phenolic liner that Kelly used https://www.mcmaster.com/8527K244/?SrchEntryWebPart_InpBox=garolite+xx+phenolic
- case can be reused
- maybe make 2 in case one breaks
- very thick case to accommodate a range of pressures
- 300 psi to 2000/2500 psi
- case should be rated for 3000 psi
- need to test at pressures expected during flight
- drill hole in liner to read pressure transducer
- make forward closure part of the case
- disassembly is harder
- saves on O-rings
- test with blue thunder ring
- adding o-ring on nozzle side
- glue disk to bottom
- Put steel ring on top w/small hole and clock accordingly
- propellant casting tube & liner
- Pour propellant in layers into liner
- Propose changing nozzle size to change pressure
- Smaller setup (less propellant) than large motors tested for Phoenix
- Scaling issues?
- No mandril
- Could 3d print casting hardware
- Plug and Play
- Easier to do in blast chamber
- Cheaper
- Less travel
- Data collection is easier (each fire is one data point w/one burn rate)
- Need to keep length of motor constant (affects burn rate)
- Pressure transducer on bottom
- RTV use
- very time consuming waiting to dry
- need to use RTV on nozzles
- to minimize time make nozzle integration faster
- all phenalic and graphite must be replaced
- Clocking
- also time consuming
- less of an issue if tolerancing is better
- Nozzles
- on the order of 2 inches
- will be machining lots of nozzles
- need to figure out nozzle range to get desired pressure values
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