Doug Riley's company, Aerotec, has been a boon to Gyrobee builders. In addition to supplying specialty components and materials kits, he has also been working on one of his own since acquiring Doc Watson's project last year. You can find extensive flight reports on the Rotorcraft Conference, but here are some quick notes he supplied following the maiden flight.
- .....the short version is that the 'Bee is very mellow. I found it impossible to make a bad landing. It will lift off with the rotor all the way back at 25 or less, but is very mushy at that speed (the more heavily-loaded gyros I've been flying just won't take off at all in this configuration). It's better to neutralize the stick and fly off with a little more speed (30 or so).
- In my first clumsy efforts, I couldn't get roll control to be as precise as on my Air Command. There seemed to be more overshoot, lag or something, so I sorta porpoised sideways. I imagine that practice will improve my timing.
- Pitch control OTOH, is rock-solid; like flying on rails
. I attribute at least some of this to the large, airfoil-section HS on the Watson tail. There's none of the hesitation and wallowing in pitch that my other gyros had. It's just amazingly steady.
- The wide gear made my ONE trip into the ditch beside the runway uneventful. Just stopped the blades and pulled her out; no rollover danger. (I did not link the rudder and nosewheel, and forgot to switch over to wheel steering after landing, so coasted off to the right as a result of engine torque; duhh).
- Very unlike my old 447 Air Command, this bird seems so far to have decent reserve power and picks up speed quite handily once you pop off. I had to back way off power to keep from climbing.
Here are some observations added after some additional flying time:
I got in some more 'Bee flying both days this weekend. I did lots of patterns, touch-and-goes, slow flight, vertical descents, idle approaches, 360's both directions, S-turns over RR tracks, and around-town cruising at 1500 feet or so and various airspeeds. Impressions from an old Air Command/Bensen pilot:
- My 'Bee is over-propped with a 66x32 on a 447. I had this prop from the same aircraft that the engine is "borrowed" from. It's a great cruiser, with lazy 35 mph flight possible at below 5000 RPM. The 'Bee's climb is best at around 40mph, however, and at this speed RPM is limited to 6K or less. I'll install a smaller prop soon (the big one fit only because I tilted the engine 4 deg. up at the back).
- Pitch stability is fine with the powerful Watson HS *, yet the gyro still reacts normally to stick movements. There's no sense of "stiffness", just the lag and overshoot are gone (good riddance). Updrafts are non-events (instead of wobbly upsets as in a tailless gyro). The gyro just rises in gentle ones, and pitches down into the draft in stronger ones. You still point the nose at the ground in an idle-engine approach (the safest kind, IMHO), and there's plenty of control power to allow this.
- I'm still wallowing around a bit in the roll axis. My first pattern, especially, looked like a DWI. I'm not sure why. One explanation is that decreased stick sensitivity also means decreased control feedback forces, so you can't feel what's going on if you're used to a more sensitive stick.
- Turns are somewhat different than I'm used to. More rotor-back pressure (back stick if a joystick) is needed in a turn to avoid speeding up . My Air Command seems to require FORWARD joystick to avoid slowing down in turns. Back pressure in a turn is more typical of "normal" aircraft, though. There seems to be some more tendency to over-bank than the Air Command has; a bit of pressure against the turn seems necessary once bank is set. Again, this is pretty normal. The craft shows the usual asymmetrical pitch response to turning: it pitches nose-up when turning in the same direction as the rotor (normally, left in the USA) and down when turning against the rotor (USA=right turn). This, of course, affects the amount of rotor-back pressure needed to hold speed in the turn.
- A mushy liftoff is possible at a little over 20, but a better one involves neutralizing the rotor just as the nosewheel comes up and then flying off at under 30. Upon liftoff, the gyro has the usual torque "twitch" (a bit of left roll). Min. speed in ground effect is 15 or so.
- I intentionally maxed my speed at 65. With this prop, plenty more speed was possible. The next prop should slow her down and give more climb. I guesstimate the climb rate to be 600 FPM now; not a bad number for a small engine and mismatched prop!
- A 2-blade prop produces a definite "drumming" in the frame. 3 or more blades eliminate this, but, of course, weigh more and cost more.
- On Sunday, there was a cross-wind coming over a row of trees on one side of the runway. This produced "trash" air at the runway, killing some initial climb but creating a good experiment in handling turbulence. There's not a great deal of difference between this gyro's ability to chew through turbulence and that of my Air Command with 23 ft. McCutchens. Both are far superior to a fixed-wing UL. (My old VW Bensen with small Bensen blades was even more turbulence-proof, but really had to fight to stay aloft.)
- Starting sequence is interesting without a prerotator. If the engine starts easily (or can be warmed up to do so and then shut off), it's easiest to start the rotor FIRST by climbing up on the seat. Once it's moving, get down and start the engine. You can instead pre-spin after engine start, but it's not safe to climb onto the seat with the prop turning. It's a stretch to reach up there from the ground, and you won't get as much of a pre-spin with just fingertips! The Rotordynes are so easy to start, though, that even a fingertip hand spin is enough. The taxi out to the takeoff point does the rest.
- I'm still evaluating the Watson rudder. It feels a bit weak in slow fight and vertical descents... enough so that I have not yet tried a vertical spin for fear of not being able to arrest it. This may be a matter of adjustment on my part, though, as the control pressures for a conventional fin-rudder like the Watson are higher than for an all-flying tail like the Air Command.
- As Ralph reports, the 'Bee flies a little nose-high. This not surprising given the hang test range in the documentation. This trait, plus my raised rudder bar and the back-raked seat, make for relaxed cruising. There is still plenty of nose-down control range to allow a very steep glide, if needed, with stick range to spare. I see no need to alter the hang specs. It might pay to set the horizontal engine carriers at an angle that puts the engine thrust line exactly parallel to the flight path in level cruise. With the usual nose-up keel position in flight, this means that the carriers would end up lower in front than in back by a few degrees. This would eke the last bit of thrust efficiency out of the engine. In any event, one should not LOWER the engine at the prop end. Also, the HS should either (a) have the same angle as the engine thrust line, or (b) be pointed MORE nose-down by lowering its leading edge. The HS should never be set to generate up-lift.
[*] I can't help adding a little note here to Doug's comment on the fine pitch stability. There is no doubt that the Watson tail is doing an excellent job, but you can see from the comments of other pilots that ALL the Gyrobees completed so far have demonstrated excellent handling in pitch. RET