Mitch

G'Day Gents,

Larry Neal recently sold a prototype 503 Emporer Butterfly to the Gent mentioned below and Doug Riley got to test fly it.

Mitch.





Doug Riley 07-23-2007 01:57 PM Da Butterfly

A student of mine bought one of Larry Neal's 503 DC Butterfly gyros. I got to play with it a little yesterday.

Fit and finish are very nice. The all-steel pump-handle joystick is very similar to the original Bensen unit (which is a good one).

The Air Command ancestry is obvious in the airframe. The front end of the frame is pure Air Comm. The remainder of the craft uses the bolted U-bracket system seen in Air Command, Sport Copter, Soma and to some extent the Gyrobee. This system cuts labor cost and time, but drives structural engineers nuts.

Larry's Metro-launch prerotator is a sophisticated version of the "long belt" device sometimes seen on VW and Soob engines; a pulley on the front end of the crank drives a long belt that runs up the mast, takes a 90-deg turn aft and powers the rotor through a centrifugal clutch. This thing is extremely powerful. There are quite a number of moving parts, including a 12v air compressor that engages the device, six idler wheels, the clutch and (I think) a Bendix. One must keep a very close eye on all this hardware up on the mast; such stuff is always tempted to take a trip into the prop.

The integrity of the pressed-together Rotax crank is an issue when taking power straight off the crank (i.e. not through the gearbox, with its slip function). I imagine that's why this unit does not give the pilot the job of directly engaging or slipping the clutch. These functions are performed by robots: the air compressor and centrifugal clutch.

Most interesting to me was the flying. The machine flies much like a Dominator, but with less pitching of the nose upon throttle changes. The large HS in the center of the propwash makes for very solid pitch stability, even on a somewhat gusty day.

The vertical tail is "half height," not "tall tail," so there's some tendency to roll with engine torque upon takeoff. With practice, you'll know just where to point the stick to minimize this effect.

I landed conventionally and didn't try out the long-stroke gear. We've all the seen the videos.

Ground handling is childishly simple. There's direct nosewheel steering using the rudder pedals, with slack in the cables that lead to the wheel to allow for slip landings. We didn't have a crosswind that would have allowed me to try this out. Direct-linked steering systems tend to be bugged by a tendency to swerve upon setting the nose down when holding rudder against a crosswind. Slack cables, springs and cams have all been used in the past to minimize the problem.

It's always fun to fly a single-place gyro after driving the tandem limo. You do get spoiled by the higher cruise speed of the big machine.

Heron 07-23-2007 05:30 PM Good report!
Thanks Doug.
Heron

Rehan K.Janjua 07-23-2007 08:17 PM Hello Mr Riley.

Thank You for the first hand info on the butterfly and its the Metro launch system. Now I know how its driven.

Would this set up be great for a prerotator set up, as you said, its powerful.

Best wishes.
Rehan

GyroDoug 07-23-2007 10:43 PM New Metro Launch Pre-Rotator

FYI - Because the assembly of pulleys at the top of the mast gets in the way of the fully enclosed cab Larry is developing for the Butterfly, he is in the process of re-designing the Metro Launch System. His new system will use a shaft to drive the same high power Pre-Rotator and give the same 325 RRPM but without all the moving parts and complexity of the current system. It will still use the robotic air compressor to initiate the process and to disengage the system. It sounds pretty exciting to me. I will let you all know more as I hear more about it.

Gyro Doug

Doug Riley 07-24-2007 12:31 PM The M-L system certainly is powerful. I didn't run it all the way up; just to 200 RRPM or so. Test-flying was tops on the agenda and we had a 4000 foot runway anyway. Also, the hydraulic brakes were getting soft and holding the the machine back was becoming difficult.

Dan LeCuyer, the owner, has run it up to 5000+ engine RPM, which apparently translated to RRPM in high 200's. He sent me a video and, while the camera tends to freeze the rotor, the soundtrack of rotor noise tells you how fast it's going.

This rig clearly capitalizes on some excess horsepower somewhere in the 503 DC's power curve -- excess relative to what's needed to spin the prop. The prop on Dan's machine is a 3-blade Powerfin that did not seem abnormally low-pitched; revs were where they should be for a "climb" prop.

Doug, it will be good to see a reduction in the amount of plunder sitting up there on the mast.

The remaining issue in my mind about this system is the protection of the crankshaft from misalignment caused by the novel power-takeoff mode. Obviously some work has gone into making this rig a "soft start" -- something that will be gentle on the crank. Whether it will shorten the 300 hr. TBO on the Rotax crank is a valid question.

coaster 08-04-2007 05:35 PM I see Larry Neal just put up some new pictures of the sky cycle on his web page with the wheel fairings on it. It gives new meaning to the word fin!

Resasi 08-05-2007 10:00 AM Doug a very clear and informative report. With your knowledge of the Butterfly have you been able to examine the various changes made on the Carter copter test vehicle or feel able to comment on the prerotator used on that( or is it the same), rotor and drive prop?

I have become interested in autogyros through seeing this one and the big prototype, and am very keen to see what experts in the field have to say about his developments.