Wednesday, October 28, 2009

Ares x-1 Launch

There is some good video of this morning Ares launch. The second video as some cool camera angles. Everything apparently went as planned, I guess the payload seperation wasn't as dicey as it looked.

Sunday, October 25, 2009

2.375" Motor Updated

I changed the design again. I decided to optimize the it for KNER propellant by adding two additional segments. The additional propellant brings the motor up to a solid L-class motor and the chamber pressure sims. at right about 1000psi. I'm hoping to have an opportunity to test fire it for the first time in early December
Update: I updated the SRM output to correct a mistake. I had been using the wrong grain OD.

Friday, October 23, 2009

2.375" Motor Update

I've completed a couple of the wooden pyrogen canisters. I also ran a new SRM simulation with KNER propellant. The result of switching from KNSB to KNER is that the burn time basically doubles and the chamber pressure is cut to about half. The drop in chamber pressure results in a bit of a drop in Isp, but for my first KNER test I'm fine with that. A sugar motor this size with a four second burn time should be pretty cool and at this point the purpose of this test is to get some experience with KNER and test the pyrogen design.

Tuesday, October 20, 2009

2.375" Motor Update

I've been talking with Magnus from AIR recently about this motor and he has convinced me to use erythitol based propellant. I first heard about erythitol on Scott Fintel's site and the biggest attraction seemed to be ease of casting as well as a decent Isp even at relatively low chamber pressures. One of the other attractive things that Magnus has pointed out to me recently is that it functions well in a motor with a high L/D. Click here to see Magnus' latest motor that utilizes nine segments and has an L/D of around 15. One slight drawback is that it's hard to ignite, but from a safety stand point this is actually a good thing.
I'll keep the length of the motor the same for now, but in the future I could conceivably lengthen the casing and add two propellant segments without any additional changes and increase the total impulse by about 36%. The resulting increase in Kn would increase the chamber pressure, but it should still be well within the design limitations of the casing and the closures.
Rather than using a hotter igniter, I have decided to add a simple pyrogen cannister to aid in ignition. The design is a small wooden cup that will have a KN/SU/RIO propellant cast into it which will be ignited by a "standard" BP igniter. For added safety, the igniter will be inserted through a NPT plug fitting that can be screwed into the bulkhead just prior to testing. The cup will have a burst diaphragm attached to help ensure a quick ignition of the pyrogen grain.
Wood may not seem like the best choice, but I used a wooden disk in the original design to insulate the bulkhead and it was reusable a surprising number of times with just a bit of refurbishing each time.

Friday, October 16, 2009

Reaction Research Society, 1958

I just noticed that the RRS website has a pdf of a 1958 Popular Mechanics article reporting on the activities of the society. It's fun to think what it would be like to have been alive at some point in history, whether it be in the midst of the "space race" or some other time. It's nice to see that while much has changed since 1958, the essence of what the RRS and other similar organizations stood for then still exists today. Whether it's medium or small size companies competing with big ones, or organizations that not only encourage but facilitate education and experimentation, or small organized efforts like SStS, the spirit of competition, exploration, and experimentation is alive and well. No need to travel back in time.

Wednesday, October 14, 2009

2.375 inch Motor Update

I finished drilling and tapping the nozzle and bulkhead. I also got the o-rings, so I'll test fit everything soon. I need to start thinking about casting bases and mandrels for the propellant; I may have some from the previous motor that I can just modify slightly. If not, I'll make some new ones.

Interesting Rocket Motor

I saw this motor on EBay, the other day. I bid on it, but unfortunately didn't win. The description said that it was 13 inches long by 4 3/8 inches in diameter. There was another (really blurry) photo looking down the nozzle that showed a graphite insert.

Sunday, October 11, 2009

New Motor, Finished Bulkhead

I finished the bulkhead. I varied from the drawing a bit by adding a pressure port so that I can measure the chamber pressure during testing. I need to order some o-rings and then I'll be able to test fit everything.

Friday, October 9, 2009

New Motor, 3D Model

I'm working on making some animation to show how this motor goes together. I did a couple of cross sectional views that pretty much show just that. In the close up view you can see the nozzle and the insulation (the reddish colored stuff). The original version of this motor didn't use any insulation. With the short burn time and steel casing , it's really not necessary. I added insulation to this motor as the plan is to eventually epoxy fins directly to the casing in order to construct the rocket

Sunday, October 4, 2009

2.375" Motor, Nozzle Update

I pretty much finished the nozzle. I used a parting tool to cut the o-ring groove and the groove where the insulation fits into. I then parted it off, flipped it, and cut the convergent side. I still need to drill and tap the retaining screw holes and I'm planning on adding some "gun blue" or similar rust resistant finish.