Is anyone here proficient in a Zenith CH-750 STOL?

A friend recently bought one (Corvair powered) but hasn't flown it yet. I'd be curious as your experience so far ...
 
This is what I posted earlier to the Zenith Aircraft Flyers Facebook group…

I’m a CFI in E TN trying to get comfortable in a CH750 STOL with a newly installed Viking engine a neighbor bought recently. I’m having problems with consistent landings. Approaching at 60mph, there seems to be practically no time to really finesse a landing - the plane just seems to want to land as soon as I start the flare, with no time to hold it off and get a nice, slow, nose-up stall landing. Watched a handful of YouTube videos, but at the same speed their planes seem to float a little more in the flare - more like I’m used to. Open to any hints. As an aside, my home base is 80TN - Big T Airport in Lenoir City, TN, and my main ride is my 2007 E-LSA Sky Arrow 600 Sport kept in a hangar/home there. Thanks in advance for any advice!

Most of the advice so far hinges on approaching a bit faster and carrying some power into the flare. Not things I like to do, but it’s generally felt that as a STOL aircraft you have to modify your normal landing techniques. I’ve only had 2 flights in the plane so far, and struggled with getting a decent landing. Plan on carrying a bit of power next time we go out to practice.
 
This one just had its 0-200 swapped out for a 130 hp Viking, based on a Honda Fit engine (!).

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Seems like an exceptionally clean install to me.

Another factor may be that a 2” to 3” spacer was added to the nose gear to increase the ground clearance for its larger DUC prop. That unfortunately results in the plane sitting quite nose high on the ground, with quite a large AOA for the wings.

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I suspect that may add to the squirelly feeling the plane has after touching down flat, even with the stick well back.
 
FastEddieB said:
Another factor may be that a 2” to 3” spacer was added to the nose gear to increase the ground clearance for its larger DUC prop.
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A larger prop is also going to provide more drag at idle, especially if it’s a lower pitch.
 
What's the stall speed from your slow-flight testing?

Advertised is 35mph.

Fixed slats are kinda like a low gear for the wing, at an alarmingly high deck angle. And a lot more drag.
Use soft-field techniques, feathering in power to arrest your sink rate. Sometimes less flap is better than full flap.

FWIW from experimenting with a Just Superstol, over the numbers @60mph = an impressive crow hop, then settle. IDK if its the draggy frame but the round-outs seem very short or non-existent. Fly it to the runway slowly, slowly reduce power and touch down.

Over the #s at very low 50's mph it settles right as the slats deploy, somewhere in the low 40's and is done flying.

The aggressive STOL planes have atypical landing profiles, both in behavior and speed/deck angles.

Dial your airspeed in midfield downwind and use pitch/power. With a Rotax 915/CS prop I use low 50% power getting to 60mph and 1 notch flaps. 2nd notch/55mph base and ease back to low 40% power for final at 50mph between 300-400fpm descent.

Make tight patterns because dragging in a three-mile final at 50 takes quite a while!

What you want to find is where the slats takeover and land slightly faster so as it slows, the normal wing stops flying and the angle of attack on the slat wing is too low to fly.

Enjoy!
 
Have you checked the airspeed indicator against GPS ground speed? Maybe you aren't flying 60?
 
Go out and do some stalls and check the airspeed indicator. I have hours in a 701. Not much difference from the 750 STOL. In slow flight, you can maintain level flight with good control and the airspeed indicator will indicate 0 due to the high AOA.
 
Thanks for the feedback. The general consensus seems to be the plane is likely nose heavy. As such, at idle, the elevator is close to inadequate to get any semblance of a flare, and a nice, nose high landing.

Suggestions so far on the Zenith Facebook forum…

1) Carry power into the flare, as much a 3,200 rpm or so, and only reduce it once the mains are down.

2) A bit of ballast - maybe 6 lbs or so - in the tail can make a world of difference.

3) Use little or no flaps.

4) Remove the leading edge slats.

#1 and #3 are easiest, and I may have a chance to try that later today. The ballast - maybe a properly secured 5 lb barbell weight to start - might be next. Getting rid of the slats seems to have very little effect on STOL characteristics, while making landings more conventional and also adding a couple mph in cruise. Might be worth playing with at some point.

Will also play with slow flight some more and 3,200 rpm stalls at altitude. And we’ll check to see if the airspeed indicator is anywhere close to accurate. I’ve always seen power during the landing in most GA planes as a crutch used to cover up other skill deficiencies, but for STOL planes I may need to just see it as another tool and not a crutch.
 
FastEddieB said:
I’ve always seen power during the landing in most GA planes as a crutch used to cover up other skill deficiencies, but for STOL planes I may need to just see it as another tool and not a crutch.
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I’ve never found power to be necessary for landing, STOL or otherwise, unless it’s a soft field (or I screw up). If I have the proper airspeed, the landing works at idle.
 
FastEddieB said:
Thanks for the feedback. The general consensus seems to be the plane is likely nose heavy. As such, at idle, the elevator is close to inadequate to get any semblance of a flare, and a nice, nose high landing.
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The only 750 I ever laid hands on had VGs on the bottom of the horizontal stabilizer.
 
FastEddieB said:
A bit of ballast - maybe 6 lbs or so - in the tail can make a world of difference.
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My friend's plane (it is a 701 and not a 750) with a Corvair conversion has the battery in the area behind the seat that is accessed by removing a bottom panel. Not sure where the plans location is but if it's FWF then moving it rearward may help. What does the W&B show?
 
Certificated pilots that are transitioning to Zenith aircraft need to lose the idea of landing "at stall speed". We were all trained to touch down with the stall horn blaring. So, very close to the actual stall speed.

My plane with VGs stalls around 32 knots which is great for avoiding stalls on landing. However, there is no way I am even thinking about landing at that speed since the vertical speed will be excessive and elevator control is marginal.

Consider the low stall speed of the Zenith as a great safety margin. However, disconnect the idea that this number is relevant on landing. You need to find a reasonable speed that maintains a comfortable decent rate while maintain good aircraft control. Join the Viking Owners facebook page for some good info. on this.

Asking certificated aircraft owners how to land a Zenith aircraft is not going to get you any useful information. You absolutely need to look at landing from a very different perspective. Once you do, you will quickly realize the amazing performance of these aircraft.
 
Lndwarrior said:
Asking certificated aircraft owners how to land a Zenith aircraft is not going to get you any useful information. You absolutely need to look at landing from a very different perspective.
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I can’t count the number of airplanes I’ve flown where I was told they required some special technique because they had such vastly different flying characteristics than everything else. None of them required special techniques.
 
Wow! Thanks for that. The owner made it sound like removing the slats was a relatively benign thing to do, but there are obviously unintended consequences to doing so.

My latest post to the Zenith Aircraft Flyers forum:

Yesterday we went up to try landing power on, no flaps. Played around at altitude with slow flight and stalls carrying about 3,200 rpm. I did the first landing carrying that much power, and in my opinion it’s too much for this plane/engine/prop combination. It certainly gave more time to “find the ground”, but it ate up at least 1,000’ of runway while doing so. And even then with the stick way back, the plane still wanted to unceremoniously plotz down on the runway nearly flat at the end. Tried less power and it seems to me 2,700 rpm or so may be the Goldilocks Zone for us in this plane at this time. We had about 12G18 or so in a near direct crosswind and that certainly wasn’t helping any. The owner is going to be out of town until 4/1 so it will be that long before we can see if we can make more progress. Thanks again for the suggestions so far!
 
Lndwarrior said:
Join the Viking Owners facebook page for some good info. on this.

Asking certificated aircraft owners how to land a Zenith aircraft is not going to get you any useful information. You absolutely need to look at landing from a very different perspective. Once you do, you will quickly realize the amazing performance of these aircraft.
Click to expand...

Good advice above. I did, in fact, join and started a discussion on this topic on the Facebook Zenith Aircraft Flyers group, with 115 responses to date. Have gleaned a lot of good information, much similar to your advice. Lots to consider going forward.
 
MauleSkinner said:
I can’t count the number of airplanes I’ve flown where I was told they required some special technique because they had such vastly different flying characteristics than everything else. None of them required special techniques.
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I sort of get this. To a point.

An instructor yelled at me once when, during my multiengine training, I made a darn good, nearly full stall landing in the Apache we were using. “DAMMIT! You can’t land this thing like a Cessna 150!” I found that you basically could, along with the vast majority of GA aircraft I’ve flown and/or taught in.

But this Zenith does seem to not abide well with the techniques I’ve used with other planes for years. Very, very hard to arrive in ground effect with power off, full flaps and a little speed cushion and get even a little time in the flare before she’s done flying. I’ll adapt eventually, but it is different enough to need to acquire a new skill set to do consistently.
 
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Have you reverified the weight and balance with scales? You could be too nose heavy with the not as common Viking engine and mount. It would be an easy test and tell you if it’s the airplane or your technique causing the problem.
 
kmacht said:
Have you reverified the weight and balance with scales? You could be too nose heavy with the not as common Viking engine and mount. It would be an easy test and tell you if it’s the airplane or your technique causing the problem.
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Good question. The owner is on vacation and said the revised W&B will be on the way shortly from the fellow who did the conversion. I thought he had implied he already had it in hand and had verified we were within limits - perhaps he did with the conversion guy before flying home from FL, but I’ll definitely want to see the new W&B data and confirm we’re ahead of the forward CG limit. As I mentioned above, others have suggested 5-10 lbs of ballast in the tailcone, but we sure need a baseline before we start moving things around.
 
FastEddieB said:
I sort of get this. To a point.

An instructor yelled at me once when, during my multiengine training, I made a darn good, nearly full stall landing in the Apache we were using. “DAMMIT! You can’t land this thing like a Cessna 150!” I found that you basically could, along with the vast majority of GA aircraft I’ve flown and/or taught in.

But this Zenith does seem to not abide well with the techniques I’ve used with other planes for years. Very, very hard to arrive in ground effect with power off, full flaps and a little speed cushion and get even a little time in the flare before she’s done flying. I’ll adapt eventually, but it is different enough to need to acquire a new skill set to do consistently.
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You might reach out to Jon Humberd himself - he's in your neighborhood - super down to earth and a Zenith expert.

Try somewhere with papis/vasis to dial in a consistent sight picture for the glidepath on final.

Then work on cutting airspeed down with pitch.

I assume the lack of ground effect is due to the high aoa.

You have to carry power to touchdown, and you're flying your roundout and flare with more than idle power, rather than bleeding off excess airspeed/momentum. Exaggerated soft-field technique.

Listen to the engine rpms at the STOL competition landings and there's a big difference between throttle application at landing between the Cessnas and the experimentals.

I went from a 172 to a Superstol and boy has it been a learning curve. The lack of ground effect really threw me, it will happily drop out of the sky many, many feet above the runway when you take power out.
 
kmacht said:
Have you reverified the weight and balance with scales? You could be too nose heavy with the not as common Viking engine and mount.
Click to expand...

I'm guessing that this is the issue. Most of the landings I've seen (live at S-n-F & videos) show an approach at 45-50, with the nose coming up in a very short flare and power being added. Even with that there seems to be a pretty pronounced dropping of the nose wheel onto the runway.

I considered building one of these as they do what they do very well ... but I find them quite unattractive (which is saying something since I fly a Sonex - LOL).
 
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