View Full Version : inflight adjustable pitch multiwing blades

John Robertson
10-Oct-09, 07:50 AM
Interesting development!



10-Oct-09, 12:26 PM
Nice development I wonder how much it will cost


Ian Brooks
11-Oct-09, 02:38 PM
More to the point - how would you keep all those sliding/rotating joints operating???


12-Oct-09, 10:05 AM
Maybe on a single engine craft, sure. A bit heavy as well. Would think it would be as useful as CURS in F1 is.

Keith Oakley
13-Oct-09, 09:55 AM
Nice piece of engineering, but whats the application? Ok so a Spitfire operating over 0-400mph speed range benefits from variable pitch, but how much would we gain over our 0-60mph range? Useful for fine tuning the fan to engine match but that only needs a few degrees range and only at setup. I guess the best use is to distribute power between say a lift fan and a thrust fan run off a single engine. But be careful the engine doesn't over rev when the thrust load comes off; I remember a lift fan exploding when the clutch took the thrust load off and the driver was slow on the throttle reduction.

John Robertson
13-Oct-09, 11:14 AM
The example shown is a lift fan in a single engine craft where I can see advantages in efficiency. It would allow you to dynamically vary the lift/thrust balance as required (most single engine cruising craft waste quite a bit of power on unneeded lift at higher engine rpm).

One of my craft (UH18) has a variable speed lift fan (manually controlled) and it is very handy at times. You can back off the lift fan speed and recover probably another 10hp or so for thrust at high engine speeds (you can also increase lift to cope with difficult surface conditions without too much thrust). It is a very simple variable speed belt drive system (variator) and, unlike the variable pitch design shown here, is well-proven (it has been used in lawn tractors, combine harversters, etc for over 60 years).

29-Mar-10, 11:20 AM
we have an old eagle mc2 (black) and we can put a rotax 447 in it if your intrested??? it would make a all round good craft for a novice. pm me for me detals.

30-Mar-10, 06:33 AM
I think it would work well on something like an electric lift system, the motor can stay at a set speed and just change lift by this method. I am almost positive that this is the reason for the design, or maybe its for a wind-tunnel, then you just bring the blades to 0 pitch so that you can quickly change your model or provide from zero to hurricane force wind without having to reduce engine speed.

2 cents