4-place Landing Techniques

[rodsmith]

[QUOTE=Battson;n47090]

Bad news sorry - at these low speeds you will still run out of authority with the profiled tail. This is common to most aircraft, including Cessna.

What is your present stab configuration. Profiled or flat? Are you saying you haven't tried the VGs under the tail yet?

[svyolo]

Battson;
You are more into the STOL stuff than most on here. What AOA are you normally at when you are doing your normal STOL type approach? I have read they fly slower than normal, but I never read any specific number.

[whee]

It is likely that since all my prior experience is in a Luscombe, which interestingly also uses a 4412 wing, I have a lot of changes that need to take place in my technique. Flying the plane and getting good performance isn't the issue, maximizing the performance is what I'll be aiming for.

I've never been a fan of landing with power on for most landings which is why I mentioned the fast descent rate I'm currently trying to get used to and figure out how to arrest without landing so significantly tail first. In the Luscombe I found a sweet spot for short landings where the plane would sink quickly, in relation to its typical approach speed descent rate, but still have enough energy that I could arrest the descent with additional elevator as the wing entered ground effect. If I got a just a bit slow I needed a blip of power to arrest the decent. If the engine quite on final I could pitch forward to a slightly faster speed which would extend my glide range if needed. I've began looking for this sweet spot in the Bearhawk but haven't found it yet.

Approaches with power certainly need to be in any pilot's bag of tricks that enjoys STOL flying. It is something I will be exploring and thanks to Battson for already figuring and laying out for us the method he uses.

My EFIS has a calculated AOA feature which apparently works quite well. Problem is I'd have to look/glance at the screen and not out the window. Same deal trying to reference an airspeed. I typically fly approaches based on feel but I've been glancing at the ASI on short final for data collection. I have no idea what my over the fence speed or my touchdown speed is. I'll continue to document my short final speed as we progress into weight and CG testing. I appreciate you guys mentioning the differences in speed you are seeing so I kinda know what to expect.

My BH flies a nice solid approach at 70mph and requires no power in the flair. At 65 I've been giving it a jab of throttle in the flair because the fast decent rate is intimidating to me. It is possible the wing will re-energize enough as it enters ground effect and I add additional up elevator to arrest the descent but I'm not yet willing to try it. Maybe in a dozen or so more hours. Either of these approaches will get me into any of the backcountry strips here in Idaho so its not like the BH is really lacking in performance when using typical techniques. But why would we settle for good enough when we can have excellent. The previous BH I flew, which had the flat tail, reacted the same at these speeds though I recall the pitch felt a little soft in flair as slow speeds.

[Battson]

Bad news sorry - at these low speeds you will still run out of authority with the profiled tail. This is common to most aircraft, including Cessna.

What is your present stab configuration. Profiled or flat? Are you saying you haven't tried the VGs under the tail yet?

Profiled tail.

I haven't tried VGs under the tail wings because I understand they make the plane very touchy in pitch control at high cruise speeds. At aft CG this would be even further exacerbated, I imagine it would be a pilot's nightmare.

[Zook]

When I flew 185 in the mountains of Guatemala I was taught to come in with power and a high angle of attack. When I learned to fly floats in a 172 they taught to approach at 5 kt above landing speed and no power. You lose the speed when you flar on landing. I do all my landings now with no power unless I mess it up and then I drag it in with power.

[kestrel]

I haven't tried VGs under the tail wings because I understand they make the plane very touchy in pitch control at high cruise speeds. At aft CG this would be even further exacerbated, I imagine it would be a pilot's nightmare.

I'm running VG's on the bottom of the horizontal stabilizer, a little in front of the hinge line. I also have a tape gap seal. No problems. Improve ability to flare at forward CG's. I wouldn't call it night and day, but a clear imrovement.

[Battson]

For clarity, I hardly use any power on my approaches. Normally the throttle is practically closed while we are on finals. There is a little trickle of power, but it's not a "power on" approach.

[whee]

For clarity, I hardly use any power on my approaches. Normally the throttle is practically closed while we are on finals. There is a little trickle of power, but it's not a "power on" approach.

Thanks for the clarification! I made the assumption based on a previous post that you were controlling the descent rate with power. It’s encouraging to know that isn’t the case. I’m still not comfortable with the descent so I’m a little on and off the throttle but I’m getting better.

[Battson]

Thanks for the clarification! I made the assumption based on a previous post that you were controlling the descent rate with power. It’s encouraging to know that isn’t the case. I’m still not comfortable with the descent so I’m a little on and off the throttle but I’m getting better.

I am definitely controlling descent rate with power, but only the most minor corrections. I did three flights yesterday from dead empty to quite heavy (whole family aboard), and self-assessed my techniques on each landing. Each time I fully close the throttle on short finals, then add "stabs" of power when required to check the approach profile. I would not consider the approach any steeper than the average aircraft.

Indicated airspeed is well under 40 knots, even fully loaded up. I am loving this new configuration, especially the new wingtips.

[rv8bldr]

Stuff deleted.....

Indicated airspeed is well under 40 knots, even fully loaded up. I am loving this new configuration, especially the new wingtips.

Dammit, Jono, now you're adding more work for me :-) I was going to use the "Bob" tips I bought, but now I'll have to make some like yours.

Sorry we couldn't make the timings work when my wife and I were in Christchurch in March. Would have been great to meet in person and have a look at your 4pl.

Cheers

[whee]

Thanks Battson. Sounds like I’m doing basically the same thing but with less proficiency and more speed. Where on the approach do you get down to the speed you are taking here, (
During my conversation with Bob yesterday we talked about performance landings. He seemed to think I shouldn’t have any problem arresting the descent down into the mid or low 40s mph without having to add power or VGs. I’ll need to fix my heavy wing issue and gain a bunch more proficiency before I get down that low. Him and I were talking ‘over the fence’ speeds but I have know idea what my over the fence speed is.

[Battson]

Thanks Battson. Sounds like I’m doing basically the same thing but with less proficiency and more speed. Where on the approach do you get down to the speed you are taking here, (
During my conversation with Bob yesterday we talked about performance landings. He seemed to think I shouldn’t have any problem arresting the descent down into the mid or low 40s mph without having to add power or VGs. I’ll need to fix my heavy wing issue and gain a bunch more proficiency before I get down that low. Him and I were talking ‘over the fence’ speeds but I have know idea what my over the fence speed is.

I am normally down to the low 40 KIAS or below 40 about a quart mile out. Provided the wind isn't presenting a risk of stall because of gusty air. I prefer to hold it stable for the whole approach.

Low 40 mph sounds pretty slow so I am betting that is indicated airspeed. With a stock Bearhawk you would be riding the crest of a stall - definitely an "over the fence" speed without VGs or power, or better yet 12" over the runway. Weight does have an impact, then again so does the accuracy of the instrument... Bob does have a extremely light plane and a simple instrument setup, we are probably not talk TAS in that context. I think he touches down at 35 mph....

[whee]

I haven’t made any changes to my approach technique or speeds but I’ve been doing a bunch of slow flight. This thing is on the cusp of stall but pretty solid at 50mph IAS and whatever power is nesessary to maintain altitude. It’s also pretty solid that speed and power off but the descent rate is just too fast for me. But I can now see how Battson is making slow approaches at around that speed.

I still don’t like landing so significantly tail first but I’m learning that most airplanes do the same during max performance landing. I’ll be installing big tires soon to add prop clearance and reduce the abuse to the tail. I think I’d prefer taller gear because I don’t need bigger tires but right now that’s not an option. I’m also going to install a shorter tailwheel tire. I currently have an 400x4 which is 11” tall and 4” wide. I’m going to install a go-cart racing slick that is 8” tall and 4” wide.

I’m about at the point where I’d be willing to fly into one of the local 800’ strips. I just need a bit more polishing on hitting the landing mark every time.

[Bdflies]

Whee, you built a whole airplane! Building a couple of extended gear legs would be a pleasant little project!

Bill

[whee]

Your right Bill. There is some analysis work that needs to be done to make sure I wouldn’t be over stressing the gear fittings but that’s easy and would be a fun activity on it’s own. In the long run extended gear legs would be a better fit for my mission; skis and moderate sized tires.

[Nev]

VG’s on the underside of the ( A-Model) horizontal stab drastically changed its landing capabilities. There a very small investment and the elevator authority you gain at very low approach speeds Will impress you

Some random thoughts/questions related to the landing techniques discussion

Would VG’s on the underside of the Horizontal Stab perhaps provide an unintended consequence of providing enough elevator authority to get into a deeper stall at slow speeds ?

Someone mentioned an increased pitch sensitively at aft CG with VG’s under the Horizontal Stab. I’m wondering if this is amplifying the effect of the anti-servo trim tab. If it was a straight Servo Tab, would the pitch sensitivity increase at increased speeds ? ie is it a consequence of the Anti-servo rather than the VG’s?

I’ve got the Dynon HDX EFIS, with AOA probe. Does anyone know if AOA can be presented on screen (limitations of looking inside the cockpit on approach noted) so that a constant AOA can be flown at all weights ? Is this practical/do-able ?

[svyolo]

Nev, I heard the planes with the profiled horizontal stabs don't do well with VG's on the tail.
All of the major EFIS's can display AOA. Having not flown light aircraft with AOA I don't know how useful it is when flying visually. I flew a lot with AOA in the military, but they had an old school AOA indicator on the left side of the top of the glare shield (left hand pattern always). Similar to some of the aftermarket types. You could use it with peripheral vision.

Some also have an aural warning, but that only tells you that your are exceeding a certain AOA. If your target and alert is 8 degrees, and the alarm goes off, you could be at 8.3, or 12. I am not sure how useful it is, but some like it.

[zkelley2]

The bearhawk trim is a servo tab. Not anti-servo. Ideally there would be no servo action at all.

[Nev]

Yup I got it the wrong way around.

[PaulSA]

Nev

I don't think the B-model stab is improved by adding VGs.

As for the AoA, not only can you display on the screen (green, yellow, red chevrons) but it also has an aural alert which has increasing "beeps" frequency up to the stall warning where it becomes "solid". And it's dynamic ....