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CH 750/701 STOL Operations, Techniques, Comparison of Configurations and Tricks-of-the-Trade?
How to get the most or almost the most out of the airplane? Maybe there's a website or discussion that has already hashed this out--please post workable links if that's the case.
Several discussions have wandered off into this area, so I thought I'd start a specific thread . . .
There's been much talk on several threads about operation of the 750 and 701 with and without slats. Chris Heintz's piece on the Zenith website makes it clear that if one takes off the slats, angle-of-climb and -descent will suffer, but isn't clear about how much. Slips without slats aren't discussed much either. And, of course, there's the ongoing flap about flap use, from "don't use any flaps until you have 80+ hours [what's going on here?], flaps are only for drag, not for lift, use 1/4 flaps for takeoff, then ease them off, etc.
I know there's a wide range of skill levels out there, and I aspire to better-than-average one of these days, so I'll be interested in and grateful for any insights from anybody, regardless of skill level. (I hope all the most skillful take a look at this between flights.)
WT
PS: I've noticed that the Valdez STOL contest concentrates on takeoff and landing distance, which is fine, but I wonder if there are any demonstrations of angle-of-climb and descent, especially with 750's and 701's with and without slats and with and without VGs? I notice that the Valdez contestants tend to stay in ground effect quite a while . . .
Replies to This Discussion
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Permalink Reply by Wayne Tyson Jr on
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Sounds like sound "advice," Walt. But since I think in terms of how much avgas a major purchase will buy, I don't know about the GoPro . . . I do have an old Panasonic AG100 I could set up, but I don't think the powers that control SEE will permit said filming. I'll have to find a friendlier airport. Maybe they'll let me set it up farther away and I can zoom in to record by 26 foot takeoffs and landings. But I need that stronger fork on there for that. And, I need more skill to keep Murphy at bay so I don't contaminate the data. I want to spend some of my gas money on a fuel-flow meter anyway, and that way I can add ballast to compensate for fuel burned between tests and pilot's weight loss from the slatted approach to a 26-foot landing and rollout.
Most heroes are dead, and the only way I am anxious to depart this earth (and return like a butterfly) right now is in Marv's great little airplane!
Wayne
Your OCD pal
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Permalink Reply by Walt Snyder on
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Wayne, when you're ready and willing, I have a GoPro that you're welcome to use.
Walt Snyder
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Thanks, Walt. I might take you up on it (GoPro loan).
W
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Permalink Reply by John Austin on
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Wayne,
I think somewhere back in this thread (or perhaps another one?) you had some questions about the main wing VG's that went unanswered.
- If you go with the Stolspeed, they're clear Lexan (polycarbonate). They come in a kit with laser cut 3M adhesive pads to stick them to the wing. You can buy the same kit from Spruce rather than have to order from Australia where Stolspeed is located. The cost is approximately $100 and it takes about 1/2 a day to install them. The most tedious part is peeling the adhesive pads off their backing and sticking them on the VG's. You'll need the 120 unit kit for a 750 and you'll have plenty of spares, although I've never had one fall off in nearly 2 years!
- The clear Lexan is paintable, but they seem nearly invisible on a painted surface so I don't think it's worth the effort to paint them. The Lexan is susceptible to damage from gasoline, but I'd guess in the worst case you just get some hazy clouding of the VG. I refuel carefully and have seen no difference in the VG's in front of the fuel cap.
- I saw an 8 knot cruise increase ~ 9 mph when the slats came off. When the VG's were installed later, they did not affect the faster cruise speed.
- There are detailed instructions for calculating optimal placement on the wing. Remember the chord of the wing includes the distance to the trailing edge of the flaperons. But here's the cheater tip: If you measure with a flexible ruler directly on the surface of the wing (in other words, not straight-line but following the contour of the upper wing skin), it's 155 mm from the center of the main spar rivet line (caution - there are two rivet lines outboard but only one continuous rivet line down the entire spar) forward to a point that will be at 7% of wing chord. You stretch a string line across the entire wing, tape it down occasionally to prevent deflecting it, and install the VG's so that the forward tip just touches this line. A provided template will hold the VG at the correct angle and spacing. The tip at 7% puts the "sail" that actually perturbs the wind at 8-9% chord which is where you want it. Works great!
- Finally, you go out and fly and have fun! But, I agree with Walt, it would be a lot more interesting to fly it as-configured, then without slats, and then with VG's.
- As always, I'm not advocating anyone remove their slats, but just relating my personal experience.
John
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Thanks a bunch, John. I ain't exactly made of Lexan, but was a little cloudy on this stuff--probably the avgas I spilled on myself years ago. Now I'm clear.
Wayne
PS: Don't worry, I've only sued one doctor in my entire life, and it wasn't because of his advice. We talked flying too much, and he ended up chopping a nerve bundle in my left hand. We kept talking flying after that, but when he told me about continuing a VFR flight in solid IFR conditions, I realized what a fool I had for a doctor and took him to small claims because I couldn't get any of the astonished surgeons who analyzed me post-op to testify in real court. Anyway, I hereby declare, under penalty of per jury that I don't consider anything you say here to be advice--just helpful sharing of experience. Umm, would be nice to have a piece of that beautiful eastern TN land though . . .
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Ok, Walt. I'll be crawling under the couch now . . .
W
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Honest, don't let the AP hold you back, it's a piece of cake, you should see the stuff I've boogered up, this one is easy
Walt
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I suppose I might come out from under the bed, but are you telling me it's a piece of cake and that you've boogered up a bunch of stuff (;>)>>? I've got these specific concerns:
1. Drilling the holes at the right compound angle(s)
2. Drilling in one stroke without wobbling the drill motor (eyeball job)
3. Ending up with the right sized hole that is perfectly circular, after deburring and smoothing the walls of the hole
4. Avoiding boogering it up in a way that could weaken the metal such that it could fail under stress even though it might look great to the naked eye
5. Getting it centered and straight
Note: The center of my concern is drilling something that thick without a jig. I'm gonna ask my mechanical engineer buddy for his opinion. If he says, "just do it," I'll have three out of five in favor--if I'm still chicken after that, maybe I can con him into doing it.
I still hope to hear from the factory/Caleb just why they don't want to pre-drill them. And, do they drill them with a jig or do they eyeball them when they build theirs? My shop is a figment of my imagination right now.
When I get those answers and have a plan that should at least theoretically work, then I can come out from under the bed and just do it. I'm gonna clear it with my retired A&P buddy too.
Wayne
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Permalink Reply by Jimmy Young on
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Wayne,
You need to get out in the shop and just drill the holes. You over analyze too much. Go out there, look at it, look at the plans, figure it out the best you can, clamp it together & drill it. The worst thing that happens is you screw it up and have to start over. Odds are highly in your favor it will turn out completely acceptable and you will have the confidence to move on to the next project. Best of luck to you -
Jimmy Young
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Wayne, sure I've made mistakes in my builds, and I've fixed the ones that mattered, and sometimes not the ones that didn't, and learned from all of them. Pick your battles. I did not compromise my front fork one iota by eyeballing it and not using a jig, and I don't want to pay the extra cost that Zenith would pass on to me if they had to set this up in a custom jig and drill it for everyone. I bought this because it's a kit, and I expected to learn something from the assembly, which I have and consider that education as valuable as the completed aircraft.
Sounds like you're going to pass this on to someone else to drill out for you, which is the great part about homebuilding, 'cause you can. Good luck on it.
Walt Snyder
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I like the idea of learning by doing and making mistakes, but I don't like rushing in where angles fear to fall. You, John, and all the other better men and women at this than I, actually move me with your generous spirits. This has been the best part of my foray back into flying at a time in my life when it's now or never. I don't know what it is about aviators--and seafarers, but they make up a fine, fine community of cooperative individuals, a phenomenon greater than the sum of its parts, great though they may be.
I will probably do it, but when I have plotted out a comfort zone the making of which is a different and separate challenge all its own. "Be sure you're right, then go ahead!" --David Crockett
Wayne
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Permalink Reply by Ken Ryan on
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Wayne, it's really pretty easy. Just make sure you have everything clamped real good so there is no chance of anything moving. One thing that might give you confidence is longer drill bits. With longer bits (12 inch) it's easier to eyeball that things are perpendicular.
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