- METEOR 2nd Interview Notes
- Date: 4-6-07
- Interviewers: Patrick Haus, Tony Nimeh, Lee Rynearson
- Interviewees: Dorin Patru (DP)
From the sheet handed to him, background and motivation for the project?
- You can almost copy-paste this from old PRPs and embellish.
- Generally, creating launch capability for satellites weighing 1kg. Particular motivation with regards to our projects is to accomplish specific tasks of each stage, an example would be improving structural/propellant weight ratio. These will be improving from both 07105 and 07109. Last year projects were separate, this year will recombine. Next year will have what is steel rocket and flying rocket now together in one.
So 08105 will be an integration of steel and flying rockets?
- 08105 will continue what both teams are doing. If needed, more steel rocket testing can be done to optimize fuel grain and nozzle. On the other hand, they also need to work on the structure to bring down the structural / propellant ratio. Each stage must bring delta V of 2200 m/s to be useful for orbit, which can only be achieved with ratio close to 1/10.
So 08105 will be optimization and integration of the two?
Aside: (DP) horizontal test stand is for steel rocket testing, vertical test stand is for flying rocket testing.
So for the second rocket stage, 08106, what is the idea?
- Same as for the third, except starting from scratch. The first stage is the same as the second.
What are the differences between the stages?
- The second stage is bigger than the third and the first stage is bigger than the second.
- Changes might be required in the test stand so they can each be tested.
- Sizes of rocket stages TBD, third stage should be 10kg, right now is 25kg.
- Just to show ratio, assuming each stage uses fuel with ISP of 220, if 3rd is 3.8kg, 25kg, 300kg. (three stages only) For four stages and the 3rd stage weighing 25kg right now, second should be around 75-100kg and 1st stage about 250kg.
- All METEOR projects are related, especially the previous rocket stages and test stand.
Returning to: what are the differences between the stages?
- 3rd stage, pare weight from 25 down to 15-20kg.
- Other stages, based on current results will be 75kg, 200kg, with the 1-to-10 ratio goal.
Aside from current guidance team leader:
Guidance team leader: Testing will be very expensive for the larger stages. Right now, we are using 9/10ths gallon of fuel per test, using at least 20-25kg solid fuel per test later.
DP: Why does book claim best oxidizer/fuel ratio 6 or 8 to 1, and testing shows 3 or 4 to one?
Guidance team leader: That was from one test, we had a lot of error in calculations.
DP: If we have error and they are right, we should be using less fuel.
Are we keeping old iterations of test equipment in service and adding to them or ?
- Yes, current equipment will test third rocket stage. Focus of test stand team is to build equipment to static test second and first stages. This will be horizontal test of rocket engines. Keep in mind rocket will be fat, fatter than long.
- Right now what we have down there is plate and railroad tie system that rocket rests on, rails will probably be too close together. Create another set of rails that are wider, theory is good just widen.
Is the 4th stage outside the scope of the new test stand project?
- Yes, with 4 stages the 4th is 1.3kg, 3rd stage 4.7 kg, 23kg, 175kg. However, currently very difficult to get smaller than what we have now. Those numbers are future goal. Just look into numbers for second and first stages.
What kind of data is test stand extracting?
- Thrust, pressure, and temperature are likely to be required. Current setup has thrust, 3 pressure transducers. (1 in feed by nitrous, 1 before injector plate) Rocket teams will tell you what you need to provide in testing capability.
How is the data taken from the stand, goes though DAQ to laptop?
- Wires come out of test stand, go to DAQ, and then have big wires leading out of blockhouse to laptop. Try to finalize electrical stuff before tests run so that test data is truly comparable.
Brought up by guidance team leader: considering implementing thrust vectoring on each stage this time?
- I cant start additional three teams dealing with guidance. Guidance team will work on thrust vectoring for all three, starting with third stage in the fall and eventually adapting it to stages 1-3. Additional possibility is to increase the number of students on each rocket team by 2-3 EEs and 1 ME and incorporate the guidance of each stage into the rocket stage projects. Guidance SD team deals with central control, rocket stages deal with implementation (vanes) on each stage.
So a new part of the project scope is to integrate thrust vectoring into each of the rocket stages?
- Yes. In first four weeks well look at concepts, and well settle on what can / should be done. Might be vanes, but are other ways such as nitrous jets through the nozzle. Top stage will probably keep the thrusters package that theyre currently working on, but lower stages may need to use thrust itself.
- Stage teams will decide what type of actuation will be used for each stage. Stage teams know best the dynamics of the stage. Concern that guidance team will be sort of out of the loop for rocket stage control concepts. Stages and guidance will be fall spring.
Will the integration of thrust vectoring have any impact on the test stand / will anything be required as far as testing of the thrust vectoring from the stand?
- Guidance will not be tested on the stand, has to be a flight test to get info. Horizontal will be mostly straight thrust. Might test reduction of thrust due to addition of vectoring components but no additional equipment would be needed.
Short summary by DP as guidance leader was leaving:
Stages and guidance will be run fall-spring, stages will look to incorporate thrust vectoring.
At the last meeting you mentioned testing stage separation on the test stand?
No, stage separation will be flight tested - mechanism will probably be tested on the ground but not part of horizontal test stand.
- Long digression into vertical test stand stuff. Discussion of sensors for horizontal test stand:
We have infrared temperature sensors to check the outside temperature of the rocket. (DP)
I would like to see pressure sensors on the inside so we can cut the fuel if we have a pressure spike, encountered this problem before. If it fails and we don't have readings we don't know why. (Mike S.)
- Digression into reasons why we cant ground test flying rocket stages larger than the third stage, plume length, etc. Not planning to ground test them anyway.
Total height of rocket should be less than 12-15 feet. (DP) Right now 3rd stage is about 50inches, will need to incorporate the chalice design where stages are interlocking. Length constraint is because of guidance concerns. First and second stages not more than 5-6 feet and ideally 4 feet so can ground test. Next year will investigate and see what can be done to shorten the design.
Nose cone for actual rocket is different for testing and flight, flight cone cant withstand the forces of testing, things slightly different between testing and flight.
Need 10x diameter of nozzle for good plume behind exit.
Do you see the first and second stages having a physical prototype by the end of SD1? When should the test stand be ready for testing?
- During fall the stages will have to use the existing test stand. SD1 is for design purposes, stages will decide on shape and size. End of SD1 is finish of paper and pencil design, winter can order stuff, etc.
-Multiple conversations on several topics, additional testing of existing stages for preliminary data, something about vertical test stand. Difficult to hear.
-Discussion of possible future meeting times.
Wednesdays at 9am looks possible. Meet in new SD space.
Where are METEOR materials being stored?
- Nitrous is in machine shop, httb in flammables locker. Metor room is in new building, supposed to be mission control but more stuff is there now.
--- Please note that all information is correct as of date and time listed at bottom of webpage ---