What is "radial force phenomenon"

[slowrotor]

The VTOL Curtis-Wright X-100 claims to have used a "radial force" from the props to augment the lift. Anybody know what this "radial force" is?

Click here to read about it. http://vstol.org/wheel/VSTOLWheel/Curtiss-WrightX-100.htm

Thanks
slowrotor

[IHL]

It sounds like a tilt rotor to me .

[Dave_Jackson]

Assumptions;
During forward flight the propellers axes' are facing forward.
The prop/rotor has a 1/rev cyclic control.
The prop/rotor under consideration is turning CCW.

Guess;
At 3 o'clock the blades have a vertical pitch. No thrust and minimal drag.
At 12 o'clock the blades have a +/- 45-degree pitch and propel the craft forward.
At 9 o'clock the blades have a horizontal pitch and push the craft up.
At 6 o'clock the blades have a +/- 45-degree pitch and propel the craft forward.

Ie. During part of the rotation it is an axial fan and during part of the rotation it is a radial fan.

PS. to the above guess;
Perhaps the above takes place, but the above pitch angles are modified because the prop/rotor only rotates +/- 60-degrees from vertical when in forward flight.


Last but not least
Perhaps someone who knows what they're talking about can give the real facts. :uhoh:

[NickLappos]

The propeller (or the rotor) develops a strong sideforce when it is subjected to an angle of attack. It is called the "H" force when helo engineers discuss it.

It is fairly easy to see how it is formed when you look at a prop that is operating at some angle to the free stream, where the air is entering the disk at an angle to the prop axis. The angle of attack of the blades varies as the blade sweeps with or against the relative wind, and the force is created. It is also the "P" force that requires the left pedal on climbout in an airplane, often inaccurately called "torque"

The big paddle props on that aircraft were clearly optimized for this H force. The vibration and strong prop moments, as well as the lift variences in turbulence probably all helped kill the idea, thank heaven!

[Three Blades]

Whilst Nick's answer is much more likely to be correct, I did like Dave's idea of bringing the Voith-Schneider concept to aircraft !
http://www.voithturbo.de/vt_en_pua_marine_vspropeller.htm

[NickLappos]

Dave mentions a very good idea for water propulsion, here is a US Navy ship that uses the propeller, note the turn radius:

http://thesaltysailor.com/51turn.gif

I am not sure that concept has direct application for helos, but in reality, the helo's rotorhead is a cousin of that propeller, isn't it?

[slowrotor]

I get it now.
The props take over the function of lift that would normally be provided by wings in cruise!

I did not notice the lack of wings on the X100, silly me. I thought radial force was some process that helped augment the hover thrust.

Thanks Nick and Dave.

[Dave_Jackson]

slowrotor,

The Voith-Schneider idea that was referred to by Three Blades and Nick may have been considered for VTOL craft, and perhaps it still is.

There was a picture put on PPRuNe about 3 years ago. It appeared to be about 80 years old and it showed a man sitting at an aircraft that operated like farmer's combine.

In addition, about a year ago a large US aerospace company was granted a patent for a VTOL device that, as I recall, appeared to be conceptually similar to the above concept.

I was unable to quickly re-find either of them.

Dave