Autogyro Rotor Tip Rockets


Gyroplane. (The propeller is behind the pilots back)

An autogyro - also called gyroplane - looks very much like a helicopter, but the rotor is not driven. It rotates freely. The autogyro is instead driven forward with the help of a propeller, like an airplane.

An autogyro needs to roll faster and faster on the field before the rotor spins fast enough in the wind for the autogyro to lift off. 100 meters or so of runway is needed for take-off. Many autogyros have a link shaft from the propeller engine and a cogwheel drive so the rotor can be pre-rotated before take-off. The take-off distance required is then shorter.

If the rotor is pre-rotated with tip rockets it can take-off vertically like a helicopter! So far, tip rockets have been tested on very few autogyros. The best known project is Fairey Rotodyne. Fairey Rotodyne could carry about 50 passangers and the first flight took place in 1957. Vertical helicopter style take-offs and landings were made, using the tip rockets. Rotodyne was cruising at 310 km/h (!) with help of the thrust from propellers and with the rotor spinning free. As the tip rockets do not give a torque force that want to twist the autogyro in the opposite direction, there was no need of a tail rotor as is the case for a helicopter. Despite the project was a tremendous technical success it was still finally cancelled, because the noise was said to be too high when starting and landing in heavily populated city centers.


A movie presentation of the Fairey Rotodyne project


PEROXIDE PROPULSION ROTOR TIP ROCKET PROJECT

DEVELOPMENT Year 2003 -2004
I presented the idea to install and test hydrogen peroxide tip rockets on an autogyro, at the Swedish Rotorcraft Flyingclub's annual meeting at Gävle-Sandvikens Airport on May 30, 2003. The members found it very interesting. In September 2003 we started the project. The first prototype system was installed on a gyro glider during the summer of 2004.

First gyro glider with tip rockets. Summer of 2004

The system was a great success! We COULD really make vertical take offs!



When pulling the glider forward, right after it started to lift we could make very nice and stable 0-roll take-offs, as shown on this movie:



DEVELOPMENT 2005 -2008
This first system was damaged and had to be scrapped, later in the summer of 2004, after a demonstration when the rotor struck the long grass at take-off and the glider fell over on the side. Goodbye, rotor!

We continued the development of rotor tip rocket systems though. The work is reported in the application archive found on the right side of this page.


NEW ROTOR TIP ROCKET SYSTEM (June 2010)

We have built a new rotor tip rocket system.

This time we have chosen to have an an atmospheric peroxide tank (no pressure!) and a fuel pump, instead of a pressurized tank.


Peroxide tank and pump (driven with a battery screw driver!)

The tip rockets are embedded in the rotor blades. Only the nozzles are sticking out outside the blade tips.
The rockets have double parallel catalyst chambers to reduce pressure drop.


Rocket drawing


Rockets before installation

Bolting the rockets to the blades

Covering the rockets with a Al plate skin

Rocket installation ready!

The design of the rotor head with peroxide transfer lines can be seen on the below drawing


Rotor head. Standard type and with fuel transfer lines.

Testing of the Tip Rockets on a Powered (!) Gyroplane
We are now testing the the tip rockets on a propeller powered gyrocopter for the first time! Up to now all test have been on a glider gyroplane.

It is a Ken Brock II gyrocopter owned by Clark Cogan, Franklin, Indiana.


Clark Cogan (Gyro Owner and Test Pilot), Gary Goldsberry (well known PRA President during many years) and myself in front of Clarks KB II.


The propeller motor is a MacCullough. Unfortunatelly Clark had a problem with his "Mac" in the summer of 2010 when we started the testing. Of some reason it developed far less than the 70 hp it is rated for. He did not come up in the air until the summer of 2011

On July 13 2011 he made the ultra short take-off with the rotor tip rockets, shown on the video below


This is the first ever ultra short take off with HP tip rockets on a propeller driven autogyro. Congratulations Clark !!

Clark made many rocket powered TO the summer of 2011, like for example the one on the below video:



Installing a pressurized fuel tank, April 2012

Clark liked the system from summer of 2011 with an atmospheric tank and a pump, but it was not powerful enough to make a perfect VTO as long as the pump was driven by the cordless Dewalt drill. The take-offs were more like zero roll, steep climbing take-offs. He also experienced stick shaking repeatedly.

These were the reasons I visited Clark in April 2012 and we replaced the plastic fuel tank and the fuel pump with an aluminum fuel tank and an on-board compressor that can pressurize the tank to 200 PSI. There is also a 12 V battery for the compressor motor and a fuel valve. No pump is needed with this set up.

We started off testing the new system with the gyro tied down on Clarks car trailer:

The new set up was more powerful than the old one. The video shows that the gyro with Clark on it plus the trailer wanted to lift!

Clark also tested taking off with the modified system:


It was a nice take off, but it was not much more true vertical than last summer. He said he COULD easily have done a perfect VTO though, but this first time he took his time and opened the flow valve slowly and no more than 10%. If he had opened the valve fully, the gyro would have popped straight up in no time!

There is still some stick shaking, but less than before. Clark prefers to practice more and make sure the VTO is really stable before he makes it perfectly vertical - for safety reasons.

This article was updated on May 4th, 2012