Final Design of the Rotor Tip Rocket System, Year 2005
March 2005
I have been working intensively with the system in January and February. After more than 30 test runs and over 60 minutes of operation I have now come to a final design of the system, because it is now easy to use, reliable and works well.
DESCRIPTION OF THE SYSTEM
THE PEROXIDE TANK
The original goal was to use an atmospheric tank and let the rotor do the whole job of creating a pressure at the tips, by help of the centrifugal force. This did really work! –But not perfectly well, because there were frequent slow downs and interruptions of the peroxide flow.
The final solution is a low pressure tank, with maximum pressure 5 bar (75 psi). The total volume is 10 litres (2.6 Gallons). The net peroxide volume is 8 litres. The rest of the volume is for pressurized air. The air pressure is created with a sturdy hand pump, mounted on the tank. The pressure is pumped up to around 4 bar before start and is gradually decreasing when the tank is emptied, but the thrust of the rockets is almost constant all until the tank is ran empty. This is because the rotor centrifugal force is still making most of the job to create the rocket inlet pressure at the tips.
The tank is semi transparent so the liquid level can be seen. There is also a litre scale on the tank.
PEROXIDE FEED LINES
The lines are made of flexible Polyurethane hoses. The hoses and the rest of the feed system is approved for 16 bar pressure.
FLOW CONTROL VALVE
The flow is adjusted by squeezing the valve handle with the palm of the hand. The fingers are left free to control the propeller engine throttle. As soon as loosening the grip, the flow stops. There is also an option to lock the valve in open position.
CONNECTIONS TO THE ROTOR HEAD MAIN BOLT
Before, I used a high pressure rotating union under the rotor head and a flexible steel hose thru the hollow rotor head. The final solution is a threaded coupling at the lower end of the main rotor head bolt and a threaded swivel coupling at the upper end. The rotor head has an 8 mm hole drilled through. See Drawing
ROTOR TIP ROCKETS
New check valves
The rockets now have a check valve in the inlet end of the catalyst pack. These valves are important because they prevent the steam flow from going backwards, which could happen before. The peroxide flow was than interrupted and there could also be a pressure peak in the upstream part of the system. Before the check valves were installed, the rotor in fact tended to accelerate for a while instead of slowing down when the throttle valve was closed. This was because some peroxide with high pressure was “locked in” between the throttle valve and the rocket nozzles. This phenomena never happens with the new check valves. The rockets now respond very smoothly to any adjustment of the throttle. In fact I have filed a patent application for this solution, because I feel it is unique enough for a patent.
Catalyst pack chamber
The chamber has not been changed anything. The outer diameter is still 20 mm. The chambers fit well in 8H12 rotor blades with 8 inch chord. Those of you with 7 inch chord blades will have a tight fit. Therefore you can order the chamber with 18 mm diameter as an option, if you just make a note about it in your purchase order. I have to clarify though that the rocket thrust may be somewhat lower because the pressure drop over the cat pack will be higher.
Rocket nozzles
The nozzles for sale will be quite similar to the prototype nozzles. The only difference is the flange connection is made somewhat more sturdy.
The throat diameter is 8 mm. This gives the thrust big enough for about 320 rpm rotor speed of my 22 feet rotor in less than a minute. If more thrust is wanted there is space enough for drilling up the throat to 10 mm, which should increase the thrust with about 50%.
Weight of the system
Tank and feed system: 2 kg
Rotor blade pipes (1/2"): 0.28 kg/meter
Tip rockets with silver cartridges: 0.5 kg each
Go to Year 2006 developments
This article was updated on July 28th, 2007