The motors: 

2007-08-12 (Regeneratively Cooled)

minimotor  (Small Regen Motor)

2006-12-09 (Running on gaseous nitrous oxide) Video

2006-11-11 (Ball Valves)  Video

2006-06-06 (Monotube) Video

 

Documents:

 Bi-Propellant Design Spreadsheet 

Links:

http://www.sarocketry.co.za/

www.nakka-rocketry.net

The latest News

 

7 April 2009 - Work has interfered with life terribly this year. At the moment I'm stuck in Kazakhstan. Here is a photo I took of the RSA3 rocket at Zwartkops air force base in Pretoria South Africa. 

There was also this Bristol Siddeley 605 take-off assist rocket engine burning peroxide and kerosene

17 August 2008 - I  decided to change the injector as shown below. The nos gas will flow axially through the 8 holes and the fuel wil be 2 impinging flows in the center (brass insert). I made the brass insert today and will machiine the aluminium soon.

 

15 April 2008 - I tested the prototype servo ball valves (see 14 April) under pressure. I used CO2 to pressurise the ball valves and see if the servo can still turn them. Success! It still works. Here is a picture with the hydraulic pipes attached:

I loosely put the prototype in the motor to see if it would fit:

 

14 April 2008 - I put together this actuated ball-valve this weekend. It needs to be stiffer but that is easy to do.

28 February 2008 - I assembled the motor with a short sleeve (to be able to see the spray pattern) and tested the valve. It opens beautifully but doesn't close properly when you remove the pressure :(

14 February 2008 - Here is what the assembled plumbing would probably look like (for static testing at least)

6 February 2008 - I tested the piston valve last night. It works! I pressurised the system with CO2 and then used a nos solenoid valve to open the piston valve. Now I need to cut the o-ring grooves in the graphite nozzle insert and assemble everything. Then we can test again.

 31 January 2008 - Here is a bad quality photo of the cylinder for the piston valve. It is a prototype and in the flight model we will remove lots more material.

26 January 2008 - No. The valves are not finished. I was concerned about the force needed to open the ball valves. (And the cost of 9+kgcm servos) So we decide to investigate piston valves. The idea is to use a small needle valve to open the piston valve for the main flow. This solution should also be scalable for bigger engines. Here is a CAD drawing Justin did. I plan to machine one this week (if work doesn't interfere) and do some tests.

15 January 2008 - We had a good meeting this weekend. Decided to keep it simple. KISS gives us the best chance of developing a small liquid rocket engine that will be reliable. For this small motor we will use a solid fuel to ignite the liquid propellant.

20 December 2007 - The new plan is to use a cordless screwdriver to turn the valves. Here are some progress photos:

5 December 2007 - I'm busy with putting servo motors onthe ball valves. I measured the torque required as 0.5Nm and 0.91Nm for the two valves I bought. My servo only does 0.4Nm. So I have to make another plan.

10 October 2007 - I'm busy looking at catalytic decomposition of nitrous oxide to use as an igniter. Here is a Cobalt Oxide cylinder I made. It is heated with nichrome wire wound through the hole. In testing it quickly heated to 350 degrees C. Now to add nitrous oxide!

25 September 2007 - The new motor is almost completed. Frans is machining the graphite nozzle insert and I have to make all the starter grains for testing. We are looking at starting it Rattworks Tribrid style.

12 August 2007 - OOPS!

Sugar starter grain going:

Nos and petrol kicking in:

A millisecond later:

10 August 2007 - We plan to test again on the12th of August.

New fuel injector for the regeneratively cooled rocket engine:

23 July 2007 - The regeneratively cooled motor was tested on the 22nd. It was great! Check the page for more detail 2007-07-22 (Regeneratively Cooled)

4 June 2007 - Frans bought  a Velleman kit with an RF remote control (50m range) that controls up to eight relays. He has finished assembly and this is our new launch/test controller. All the plumbing is also ready so we are very close to testing soon

k8058

k8056

8 May 2007 - I bought some viton o-rings for mini motor as the previous o-rings took a beating in the last test. I also reduced the injector size for the starter (.25mm for the fuel and .3mm for the nos)

I repaired the regeneratively cooled motor and hope to test soon.

We tested the mini motor on Sunday (2007-04-15) and it works.
The motor took a while to start. It was like an old two-stroke motor spluttering. But when it stabilised and I opened the main valve, it burst into life. Lovely.

Here is a screenshot.