CH-701 Delivery Advice

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CowPilot

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I won't get real specific until the deal goes through, but I expect to be delivering a CH701 with the J2200 soon, FL to NY USA.

Any advice from Sky Jeepsters will be much appreciated. I haven't flown one of these before, but I ain't skeered (I've flown a few airplanes).

1st post/hello btw
:ban:
 

CowPilot

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Oh, and I'm NOT delivering it on a trailer (no advice on safe trailering, please). It looks like too much fun, not to fly it home. :D
 

CowPilot

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Slatless shortwing with VGs, stock quick-build with Jabiru conversion kit BTW, all assembled neatly. I'm already in love, and I still haven't met this crate in person.
 

CowPilot

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Are all the CH pilots asleep on the bottom of the world or something? I'll settle for advice from any bushish pilots.
 

skeeter_ca

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Hmm.... Don't get mad.

Your question seems a little vague to me. Are you asking how to fly the plane or tips on it's handling qualities? Are you buying the plane for yourself or just transporting it? Perhaps getting a check out ride from the seller would be prudent. What is your flight experience?

skeeter
 

CowPilot

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I'm not mad, darn it. I'm curious. and thanks for the reply: What's a good RPM in an all-day headwind? What's the most efficient zero-wind altitude? How far do you stuff the nose down when it goes BANG shhuddershudder on takeoff (although I don't expect it will)?

Slatless, Jabiru 2200 fixed wood prop, VGs, 170lb pilot 19 gals, 30 lbs stuff.

7khrs cubs to caravans. I think I'm gonna fly it like a big slow empty caravan. Or maybe like a Spad. It looks like it climbs much like a Spad or a baby helio courier.
 

CowPilot

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The current owner is very helpful, and I'll fully avail myself of his knowledge when I arrive for delivery (and have the flight manual in hand). While learning about any unfamiliar airplane (especially before ferrying a new type) I try to seek all the advice I can, from as many sources as I can find. Along with delivering airplanes I'm often preparing myself to teach in them- so it's important to learn enough to have competence as an expert on the airplane as a CFI- if not by first flight, then upon delivery. In my experience as a roving instructor, pilots who know their airplanes' flight envelope well and fully (more than necessary for very basic local flying) are very few, so depending on a single new acquaintance for all one's advice can be a long shot. Sometimes I've gotten great briefings from sellers, and on some I've been appalled that some individuals are licensed to fly. Sometimes in the homebuilt industry I've found piloting skills (academic and physical) to have atrophied over the building process.

I probably won't see tailwinds this trip, but at what part of a cruise-climb do Jabirus start to noticeably lose power?
 

CowPilot

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...well before fuel exhaustion that is :D - I'm wondering what's a practical ceiling to expect with the J2200? Optimal Altitude (where peak true airspeed occurs) would be useful to know, too. I realize Rotax and other are more common, and I'm interested in those numbers too.

I just found the following in an earlier thread here that has been very helpful (thanks, Rhino):

...The CH 701 and CH 750 are STOL aircraft. They have high sink rates designed into them deliberately so that they can do steep approaches into short strips, particularly those with obstacles at either end. The down side is a high sink rate being the normal approach, and the aircraft almost stop flying when you chop the throttle, so you better be ready to land. However, Zenith has new vortex generator (VG) kits for the horizontal stabilizer now that vastly improve the flare and landing characteristics. Those who have looked closely at the aircraft will have noticed that the horizontal stabilizer is mounted inverted as compared to other aircraft. That's for STOL capability, but it also creates a condition where the horizontal stab actually stalls before the wing does. That was one reason for the abrupt 'flare' and very high sink rate at rotation for landing. The VGs dramatically improve that function, and both aircraft regain a true 'flare and float' capability at landing.

Full aft stick at landing in Zenith STOL aircraft has little or nothing to do with the flare and touchdown. Since the aircraft is designed to be used at rough/unimproved landing sites, pilots are taught to use full aft stick upon landing so as to minimize weight on the nosegear in order to reduce stresses on it when hitting bumps.
I'm not sure if the plane I'm ferrying has VGs under the h stab. If not, it sounds like I'll be recommending them. IMO nothing marketed as a STOL airplane should have any problems in the elevator-authority department. It's a dangerous corner in canards, Ercoupes, some Cherokees, and other airplanes, when loss of pitchup authority creeps into the slow end of the envelope. I think that all aircraft that can experience elevator stall in the flare should have clear annunciation (a nice big flashing red light would do) whenever airspeed gets below that at which the nose can be brought up through the horizon power off and wings level, in all landing configurations, and while loaded at the forward cg limit, light or heavy. If you've studied accidents in the types I've mentioned, then you know that a lot of people have been sadly caught by surprise during emergency landings with restricted elevators or tail stalls. Any competent pilot must be able to recognize the onset of stall buffet. Any competent pilot must also know if elevator authority can come into the engine-out equation before the stall buffet, and fly accordingly (I would prefer it that all airplanes could reach critical angle of attack in an emergency-landing situation, but it isn't true, is it). Many accidents with the front bashed in are attributed to wing stall, although the aircraft was loaded/configured in such a way as to make both a wing stall and (unfortunately) arresting a slow-airspeed descent impossible. This is a dangerous gap in accident reporting and flight training. Some designers (not Chris Heintz) may consider it safer to have an airplane behave as a lawn jart when too slow, but I don't agree with them: I want full pitch control into and through the wing's stall, please (canard canards notwithstanding).

Of course power off approaches can be done safely with limited elevator authority, so long as the pilot is conscious of and avoids the perils of getting slower near the ground than will allow for a flare to a nearly level flight path before ground contact in an engine-out situation. Many pilots are flying around right now in many airplanes with loadings and practices that will likely end the flight with a nearly flareless nose-down crash should the engine fail: The pilot subconsciously pulls to feel the stall buffet short final, and is now unable to arrest the descent rate before impact. This gets into the importance of pilots perceiving as viscerally airspeed the wing's angle of attack and the flight path. Accident reports often write this scenario off as a "stall" accident, but these aren't proceeded by the sensations taught in "stall" avoidance: The ground is coming up, the nose won't, and the engine is unresponsive- not safe, not good- I won't let myself or my students "fall for it".

So I like steep approaches power off, and I do them a lot. I'm perhaps a little bit fanatical in teaching my students to be most familiar with power off approaches (and landing flares). No doubt, our "normal approaches in the 701 will not look so normal to the uninitiated. This will also reinforce our training: when a "normal" modern power-on approach to landing seems more familiar, then we aren't practicing power off as much as we should be; we aren't ready for what can happen. What is the minimum approach airspeed, full flaps, power off, that gives an average CH-701 an acceptable flare margin (enough speed to arrest the descent and make small corrections for minor winds or obstacles)? I would imagine it possible that a lighter load could require a higher approach speed than when heavy, not only for the roundout but also the necessary kinetic energy /penetration to set the plane down exactly where it's intended when the wind is puffy.

As for blending in with cleaner faster traffic around city-slicker airfields (the ones with all that pavement, and controllers and such) my custom is to always request a mid-field landing on long runways with "slow" airplanes (the ones that come down steep power off) This means that we can fly cruise power all the way to the runway, at a shallow descent angle (VS 5x GS for 3 degrees), and transition to any necessary landing (even a real emergency) with runway beneath. Midfield also happens to be what the GPS is reading out, so the math works well to get to the point where the power comes fully back: I'll use 500' for the 701. Most air-cooled piston engines are well cooled after a long descent even with power. I don't believe in the "shock" cooling meme- I don't avoid rain showers to keep from short temperature transients. After an engine has had a few minutes in any phase of flight (climb, cruise, descent, landing) I do not hesitate to shift between any adjacent two. I don't know much about the Jabiru, but other than top-end lubrication it seems like a mill with as healthy a heat budget as the small Continentals and Lycomings installed in commercial trainers, that consistently make TBO with a LOT of throttle-jockeying along the way. I'm hoping that the Jabiru is a good bushplane engine- that is, you can do just about anything you want with the throttle at any time (excepting overspeed) without rational concern for harming the engine.

Edit/ On lateral control: I do like the crosswind advantage of a stabless "flying" rudder. One thing to watch out for, that I learned instructing in CH-2000s: If a pilot's foot should slip off the right rudder pedal while initiating a go-around, it can get instantly dangerous (very high-rate and dramatic yaw motion: snap-roll territory). We have to be sure-footed about those pedals near the ground. One of my students let her foot slip off, and almost caught a wingtip as I watched her (my mouth gaping open, no doubt) from the tower. She got it back- but just barely. Before that scene, I had not considered the implications of no vertical stabilizer, when a foot slips off a rudder pedal. Instructing with the CH2K I also found a rather vicious tuck in the CH2K slipping with full rudder (AFAIK it's still inherent in the design, it's there in all models I've flown, and little talked about). Hopefully, there are no elevator-blanketing issues with the CH-701 with hard over rudder. On that subject, I'm curious about what approximate speed the elevator can be felt to be in the wing/flaperon wake.
 
Last edited:

Rhino

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Don't thank me. I haven't been able to help, unfortunately. I'm not familiar with the 2200. However, I notice you're also asking on Zenith.aero, and it looks like you're getting more responses there, so hopefully you'll get what you need.
 

CowPilot

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There are many very knowledgeable people contributing to both forums, and I've learned a lot here an elsewhere about the 701. I'm sure that all this will be much clearer to me, once I fly a 701 on Friday.

I'm hesitant to discuss slatlessness much on the ZA forum- It's understandably hard for CH & Sons to embrace the discarding of such a prominent component, even if it turns out that the slatless+VG proponents are undeniably correct. I think Zenith Aircraft has a very plausible and honorable rationale for nodding to the past and still adapting with the times: When the 701 was first developed, VGs had not been proven effective for such low-speed applications. By all accounts I've seen so far, VGs in lieu of slats do produce very similar STOL performance, better roll control, and also provide measurably better efficiency in climb, cruise and glide (6-10 mph cruise speed improvement for example).

For similar reasons, I'm shy about discussing power-off elevator effectiveness on the Heintz' website: In my basic research about the 701, I've seen several flight reports and anecdotes indicating that some 701 examples do run out of nose-up elevator authority when flown at forward CG, full flaps, and power off. In some accounts, the elevator reaches the up limit of travel well before any power-off incipient-stall buffet begins.

Praise for a "mush" or "rocking" in lieu of a power off stall always raises an eyebrow with me. Many recent designs include this "benefit". I'm one of those stubborn old-school types, who considers the management of angle of attack to be entirely the aviator's job. When engineers involve themselves in that task through design, they most often (IMO) compromise a pilot's ability to get the most performance out of a wing throughout the flight envelope, and sometimes pilots don't realize the sort of control that is absent, until the moment they need it most (perhaps low-altitude engine failure).

Since 701s reportedly have a predictable coordinated stall break configured clean and power on, I expect there's a similar benign stall progression in the dirty and power off configuration- provided there is sufficient elevator authority remaining, to reach critical Angle of Attack without the help of power and propwash.

I find learning, teaching, and retaining Alpha awareness / stall avoidance a straightforward process, in an aircraft that provides full control through the stall in any configuration. It's not as straightforward, or common (in my experience) for pilots to develop and retain keen recognition of elevator authority margin, in the context of unexpected power-off arrivals, flying airplanes with pronounced elevator authority deficiencies slow and power off.

Put another way, the onset of stall is generally more perceptible than the onset of insufficient elevator authority; it's easier to feel a rumble at the wing roots approaching a stall. It's easier (once attuned) to feel the drag curve at any weight or loading, than it is to perceive the remaining reserve elevator power as a limiting criteria. In traditional bush aircraft such as the Super Cub, a pilot can feel what the wing is doing, and so operate safely in and out of the early buffet, with full pitch authority throughout... also with eyes outside, where they belong.

In airplanes that "run out" of elevator before the stall, the first recognized indication of trouble in an engine-out landing or bounce can come too late- the ground coming up fast, the elevator at or near the up travel limit, and no options remaining to arrest the sink rate or get to a proper touchdown attitude before impact.

One operational means of coping with a too-forward CG and/or insufficient elevator authority is establishing a minimum approach speed that allows a full flare to level flight without power- a crude substitute (IMO) for flying the wing by feel. Such an arbitrary margin as an airspeed can increase the kinetic danger of confined-area and emergency landing scenarios, and a single arbitrary speed will not apply for all loading conditions. But some minimum speed for elevator effectiveness without power must be established. With elevator-handicapped airplanes, any and all approaches flown below minimum power-off flare speed are staking the well-being of the occupants on uninterrupted engine power.

That's not something I'm personally comfortable with. Better IMO to operate at a more aft CG (within the prescribed envelope of course) that provides full pitch control power off- this amounts to the operator/builder simply establishing (if practical) a more conservative forward CG limit than the designer did.

I'm curious too about the pushover effectiveness in situations of engine failure on initial climb. It seems to me that the pitch attitude change required, and the momentary lifting force necessary from this highly-assymetrical stabilizer/elevator are considerable, and a lot to ask of an airfoil with that much camber. The cambered tailplane is likely unforgiving of an excessive aft loading- prone to stall as a lifting surface. Could that be why the designer biased the CG envelope forward?

Anyway, this is not to bust on the CH-701 or its brilliant designer: It's just part of the warts-and-all process of getting to know unique airplanes well. I'm really looking forward to flying it, and welcome all advice and input I can get.
 

steveair2

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Wow Cow! That was very well said. I'm sure you will do fine with the 701.
Please give a flight report and let us know what you think of the 701 no slats with VG's. And placement of VG's. Thanks for your input.
 

CowPilot

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K23 USA
Thanks steveair, I'll try and post some impressions, and maybe a photo or two of the Vgs etc with my iPhone along the journey.
 

Wrongway John

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I'm hesitant to discuss slatlessness much on the ZA forum- It's understandably hard for CH & Sons to embrace the discarding of such a prominent component, even if it turns out that the slatless+VG proponents are undeniably correct. I think Zenith Aircraft has a very plausible and honorable rationale for nodding to the past and still adapting with the times: When the 701 was first developed, VGs had not been proven effective for such low-speed applications. By all accounts I've seen so far, VGs in lieu of slats do produce very similar STOL performance, better roll control, and also provide measurably better efficiency in climb, cruise and glide (6-10 mph cruise speed improvement for example).
Very good post to read from, CowPilot. For me the verdict is still out, but I’m sure you’ve researched this much more so than I have. It’s been awhile since I compared the two. I certainly do like the better cruise speeds which is undeniable better in the slatless designs, but the climb outs and descents are better much better with steeper angles with slats, along with shorter TO&L, IIRC. CH and sons may have a vested interest in promoting their original design as better, but so do the VG manufacturers and marketers as well with their product.

Seems like I also remember quite a few of the slatless 701’s that went with the VG’s, also tended to go with a longer wing, which makes direct comparison of the data a bit more difficult.

I tend to think the original design is still the way to go with these particular planes, but my opinion is subject to change as more reliable data comes in. :) I only see a few of the Zenith builders taking their slats out. It seems like many of the Storch, Ragwing and others leave the slats in, while some adding VG's in various places too.
 

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