Comment

Comment by Ajay Singh Shivran on September 17, 2010 at 10:24pm

Hello Rob, I am planning to install a Jabiru 2200 engine for my 701, need some help and advice.

Comment by Dwight Early on July 26, 2010 at 8:01pm

What happen to the factory Bing carb? Alltitude compensating.

Comment by Roger Wibbels on July 26, 2010 at 6:31pm

Thanks Rob for the great info. I'm building one with the same configuration, and was hoping that it would actually fly. You've proven that it actually flies quite well. What kind of approach speed did you hold, power on or off. Normal gradient and flare, or steep approach. Thanks .... Roger

Comment by Rob Craigmyle on July 25, 2010 at 10:41am

Ferry complete. I flew up the East Shore until Jekyl Island, then turned left to Northern KY for some weather avoidance, and for a visit to wait for a weather system to clear the destination. It was 14.6 flight hours covering 1383 NM, making for a 94 kts av groundspeed. TAS around 75 knots up high, 2900 RPM 1350 EGT 3.6 GPH CHT 285 Oil Temp 205. Low along the beaches at 60 kts/70 mph, OAT was 90-100, I kept power under 2700 RPM to control oil temp. CHTs stayed under 300 degrees in all conditions, power settings, and altitudes. I mostly cruised at 8,500' and 9,500' to take advantage of tailwinds, and would have gone higher if this one had a transponder- there seemed to be ample power reserve at 10k'.

I'm waiting on all the books to catch up by mail, so I can make adjustments and complete an early Condition Inspection, to address all squawks, make a few improvements, and generally get to know this machine better.

The AeroCarb will be getting immediate attention: The mixture/metering was not linear with RPM- a lot of mixture fiddling was required in flight to keep it running nice at first, and then to keep EGTs in tolerance for endurance flying. It wasn't really all that busy in steady traveling, but the present mixture-maintenance workload is unacceptable for training/inexperienced pilots and short-field ops. Some tuning is in order, and for any builders nearing first flight I would advise getting any help necessary to get smooth power all the way from from idle to "high smash". After I got the mixture well in hand on this trip she still hiccuped twice: Once at 3,500' in cruise, once at 7,000' in climb- felt/sounded like complete fuel interruption for a little less than 1 second- possibly air/vapor bubbles in fuel line. These brief power interruptions were self-correcting both times. Both times it was (of course) over nasty terrain. The whole fuel system and carb will be getting my close attention, now that it's in the shop. The Jabiru seems like a very nice little engine, but from what I've been reading, carburetion needs more factory attention.

Rudder control friction seems excessive to me (the rudder does not trail/center in flight with feet off). This slatless short-wing 701 with vgs (vgs on elevator also) barely nibbles at the stall-buffet, power off with full back stick. However, this was at a slightly aft CG, solo with ~30 lbs in the baggage area. Not unexpected, but elevator control isn't super-positive at low speed.

I was pleased to have positive control, when landing fast in gusty air and stiff crosswinds. There is not much adverse yaw in the flaperons, which something I'm not used to- I caught myself skidding in turns at first. The buffet on the skylight during slips is interesting. I wish the 701 had a little more aileron power, to match the pitch and yaw authority. If it's too gusty for a slow dogleg approach to the runway in crosswind situations, then it seems to me that aileron travel remaining is the limiting factor in conventional crosswind landings on the windward main. I can adjust to the burble pounding on the skylight, but I don't like running out of aileron while putting the upwind tire on the runway in a breeze, if you get my drift. This is not to say that the 701 does not handle wind better than many other airplanes of comparable weight- it would just be a little better IMO with a little more aileron.

Overall it's a nice airplane, and more comfortable and efficient for traveling than I was expecting a "Sky Jeep" to be.

Comment by Clemens Kramer on July 21, 2010 at 4:25pm

I have the second amature built CH750 flying in the U.S. and the first one to have an "incident"(at Sun-n-Fun no less). All but 3 of my landings had been without flaps, have the nose down, runway made, 70 mph, engine at idle, flare and touch down, very quickly too. With flaps I learned at altitude that you need power all the way through the flare, unfortunately with the short field at Paradise City, I decided to use a little flap, power, 55 mph and like a fool forgot at the flare and pulled power and the elevator went limp and she keep going straight nose in. Not hurt except pride and $ 2000 to repair. My empty CG is 2 mm behind the foreward most CG limit. I've met Ray several times and he is a very nice person but anybody that paints over stickers makes you wonder how well it was built. You will do well, just KEEP the POWER in until your done flying.
Clem

Comment by Rob Craigmyle on July 20, 2010 at 4:29pm

Thanks for the heads-up Clemens-

Ray has been very forthcoming, and from what I know so far (without inspecting personally) the airframe repair and (factory) engine IRAN seem to have been done right.

Such incidents generally lead me to pondering elevator response at low speed: Is it typical for CH-701s have a tendency to run out of elevator before the stall, when slow and power off?

I know that some builders are installing VGs under the Hor.Stab. for improved flare (and flair) so I am curious if the 701 runs out of elevator (either by travel or aerodynamic limits) significantly before power-off wing stall. Elevator effectiveness insufficient for a full stall, with full flaps, and power off at extreme forward CG is not an ideal trait in a bushplane IMO (but still manageable with keen airspeed/alpha awareness/control).

With elevator-handicapped airplanes, I've encountered as an instructor many pilots who don't understand that this condition necessitates higher approach speeds in an engine-out situation than they may be practicing. For pilots who would normally pull to the edge of the buffet to find the margin, it becomes a much more transient pull to feel how much elevator travel and bite remains. If a pilot allows airspeed to decay below a certain value, short final in a restricted-elevator airplane, a reasonable roundoff or reduction of descent rate quickly becomes impossible, if engine power happens to be unavailable before impact. I suspect that many accident reports are mistakenly written and understood in this regard: Pilots are chastened to avoid aerodynamic stalls during emergency approaches, and much talk and practice goes into stall avoidance, while many of us remain oblivious to the reality that running out of airspeed for the flare happens in some airplanes significantly before detectable onset of the wing-root stall buffet- with regularly damaging and even deadly consequences.

I've flown many airplanes with what amounts to a corner summarily clipped off the flight envelope: Engineers add "safety" by fitting an elevator of limited effectiveness at low speed. Ercoupes, Cherokees, canards, etc come to mind- and I really don't know yet if the 701 is a bird of such feather. I have adapted myself and other pilots to such airplanes, but I always much prefer it when engineers allow the pilot to recognize and manage the angle of attack near and beyond critical alpha, rather than assume that all pilots will anticipate pronounced limitation in elevator authority during an emergency approach without engine power and at forward C/G (or often, a bounced landing with delayed pilot/engine response).

I think restricted elevator authority can be more insidious than the stall, and harder for many pilots to recognize, than angle of attack approaching critical in a light airplane. This involves a scary gap in training that I find often among pilots of such airplanes. Ercoupes (to name an extreme example) where accident reports often miss the mark. To this day, many accidents resulting from insufficient airspeed to flare/arrest sink while power-off are not recognized and emphasized. Opportunity for pilots to learn about the dark side of engineered stall-avoidance is often missed. Angle of attack awareness during decelerating flight is much more easily learned (and more uniformly taught) than visceral awareness of control authority remaining when it matters most. IMO a good airplane can never run out of 3-axis control in flight, and control limits should never interfere with a full-stall power off landing or landing bounce recovery.

If the 701 really has pronounced lawn-dart characteristics slow and power off (I don't know enough yet to say it does) I'll be a little bit disappointed in this wonderful design- and I'll be looking for proven safe remedies after delivery, for the sake of the next owner.

Comment by Clemens Kramer on July 20, 2010 at 3:04pm

You must be driving Ray Miller's 701. If it is check the firewall and nose gear REAL good. It had an incident (look who's talking) at Okeechobee Airport. Nose gear first landing, trailered home, rebuilt firewalll etc.

Comment by Rob Craigmyle on July 20, 2010 at 1:44pm

If anybody knows any cruise speed changes/results with slats removed, I'm interested in that.

Comment by Rob Craigmyle on July 20, 2010 at 1:40pm

Oh, and the engine is fresh from Jabiru/latest revision.

Comment by Rob Craigmyle on July 20, 2010 at 1:39pm

Thanks, Bob and Ralph. I won't mind much if cruise is slow. I just tend to get away from interstate highways in slow aircraft, because watching cars pass me gets depressing after a few hours.

I'm very glad to hear from a 2200 CH701 flier, and I'll watch the fuel and oil. I always do a few short legs and "re"flight inspections first, on trips like this. Ralph, is there much merit to the concerns I've read about Jabiru top-end lubrication in the 701 climb attitude?

Thanks for the input everyone, I expect I'll be enjoying the airplane and the view a great deal on this ferry flight.

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