4-place Landing Techniques

[whee]

You need power on to keep the tail down, in that configuration with CG hard forward. If you close the throttle, the nose drops and airspeed increases, limiting the performance of the aircraft.
It would be hard to fly into a stall for this reason.

This is the thing I’m wondering about. I don’t need power on to keep the tail down. With just me and minimum fuel I can still land tail first with no power on and the stick not quite full back. Significant factors are likely my lighter engine so not as forward CG and approach speed is faster. Other contributing factors could be my non-servo trim tabs (more effective surface area), and 2” longer tail cone (longer moment arm).

[Battson]

I think CG is a factor, with aft CG I don't even need to trim up - let alone use any aft elevator. It's just throttle and landing. Speed is also a big factor. I can't comment on fuselage length, sounds reasonable.

[John Bickham]

Well, I've just passed the 100 flight hour mark, with 150 landings. Still have a long way to go. I'm not one of those "natural born aviators". I have to work extra just to get to the "average" threshold.
I'm still groping at approach speeds and techniques. I started with 50 KIAS (57 mph) approach speeds and 3 notches of flaps. I worked my way down to 46 KIAS (~53mph) to try to shorten my landing distances. That was ok but every now and I would experience big sink in close, that could only be resolved with a huge burst of power. That was kinda like a bird landing on a wire and missing the wire!

Just recently I've gone back to 50 KIAS approach speed and and trying full flaps. It is like starting over again.
If you are weathered in, bored and need a Bearhawk flying fix, here is a short video of my recent landing practice session. I was experimenting with small speed changes to increase sink rate. Didn't work out and landed long way too much.

https://youtu.be/EkMVaq4OgcQ

I'm hoping this video will provide a "before" reference to post VG installation. There is very little or no braking on the rollouts. The takeoffs are standard and extended for spacing with other pattern traffic. Field Elevation = 5220 ft Density Altitude was about 6300 ft.


I'm about to pull the trigger on ordering some Stolspeed VG's. I have a VG installation question for Battson. Did you install your VG's at the spacing recommended by John G? I think it is 60 mm spacing for first 3 feet from the wing tip, then 90 mm spacing.

Stalls on this day:

3 notches of flaps Idle - 37 KIAS 1500 rpm - 37 KIAS
4 notches of flaps Idle - 35 KIAS 1500 rpm - 37 KIAS

[Utah-Jay]

John, firstly I enjoyed your video... I am an aviation youtube junkie. Your landings are nice and smooth.

I am a low time Rans S-20 pilot but my instructor would tell you that you are stirring the pot with the stick on short final. There should be no need for that.

I assume (always dangerous) that your stalls are in level flight/zero VS attitude, so my question is why are your doing approaches 13-15 knots faster than your stall speed? With your hand on the throttle it seems to me you could be coming in Vso (Stall with flaps) plus 4-5 knots (Vs1.2) over your stall and be in a very safe zone.

Keep the videos coming

[John Bickham]

I did mention that I'm barely average! I'm not qualified address your points or your CFI's comment. I am probably not using the correct terminology. I will only mention that determining stall speed in my Bearhawk is very technique dependent. It doesn't want to break. There can be pretty high angles of attack and very high descent rates (mush?) before I can make the thing break. Not my intent to make suggestions on speeds and techniques. Just sharing my baby stepping to hopefully better and shorter landing distances in the future. Fly safe.

[Battson]

You need the high approach speeds without VGs to avoid that big sinker. Fit the VGs...

[jaredyates]

The non-break of the stall is related to the flow separation at the horizontal stabilizer. Adding power will make it break. If you'll be flying an approach speed at 4-5 knots over Vso in a Bearhawk, you'll either be carrying some power, or you'll have some pucker-generating descent rates. Proceed carefully!

[Utah-Jay]

I did mention hand on throttle, but I will yield as I have not flown a BH

[jaredyates]

You are right about that. Personally I really like that we have the high-sink option with the Bearhawk. It's a great tool in the toolbox for getting in over a tall obstacle and a great demonstration of the "region of reverse command." Some airplanes don't show it as well. But like all of flight testing, proceed incrementally.

[Battson]

I could never get a hard break or wing-drop with the stock wing, even with full opposite rudder. It just slid smoothly into a power-on stall in my case, and it would fly in the stall indefinitely. Fully controllable throughout. I could get a break with an accelerated power-off stall, still with total control over the aircraft.

[rodsmith]

Enjoyed the video, nice plane, and you have a great looking airport!

[whee]

I did a little flying yesterday which included landing practice. I get bored pretty quickly and I was feeling bad about beating up the bushweels on the pavement so I didn’t practice as much as I should have.

I’ll convert all my speeds from mph to kts so we all speak the same language. I’ve been thinking about changing the plane over but I haven’t convinced myself to do so.

Speeds I’m currently at: 60kts downwind to base, 56kts base to short final (bit less than 1/2mile) and slowing, 45kts over the fence and slowing. There is somewhat of a flair which I mostly mush through to a comfortable touchdown.

I leave the throttle cracked, 12” mp ish and adjust as necessary. As I pull back into the flair the throttle is closed. Occasionally I feel the need to give a quick blip of throttle to arrest the sink in the flair but this almost always result in ballooning. I’m still working on recognizing when power is actually needed in the very last moments of the landing.

This method seems to work pretty well and consistently produces a 300-350ft landing roll with moderate braking. As if a 50ft variance is consistent.

Summary of the stuff that somehow got cut off from the original post:

If the situation is such that I fly a longer final then I fly much of it at 50kts then slow to 45 over the fence and continue slowing as above. I'm still pretty uncomfortable at 50kts but the airplane is solid, I'm just not used to such slow speeds.

The airplane has more to give, both is flying slower and harder braking.

For takeoff: No fancy pilot stuff and no spectacular results. Two notches of flaps. Brakes are only held until the throttle is on its way in. The tail is lifted until the tailwheel is just barely off the ground and held there. This produced a consistent, easy to obtain 400ft ground roll.

Conditions: Zero wind, 4500msl, 30 degrees F, airplane loaded to about 1700lbs.

[whee]

Nev, If I'm flying a longer final 50kts is what I use. I'm still uncomfortable at that speed but the plane is solid and could fly slower.

[Battson]

That all sounds like you're on the right track to me. The timing with the throttle will come, just keep practicing - find a grass strip, please!

Better change to knots before everyone starts changing to kilometres per hour!

[Nev]

Don't laugh Jon - they used to give us meters and kph in China. Took a huge amount of mental capacity (I didn't have much to start with) to keep doing the conversions.

[Utah-Jay]

Whee and Nev
I have yet to fly a BH, but can’t wait. I fly slow, and typically only Vso 1.1 on short final. Obviously Vso changes with weight and CG, but the plane should settle nicely at that speed. I really think most fly way too fast. From my experience, limited as it may be, it is pretty easy to maintain a nice stabilized approach with a bit of throttle when needed and of course pitching for air speed

[Battson]

Well said.

[whee]

Whee and Nev
I have yet to fly a BH, but can’t wait. I fly slow, and typically only Vso 1.1 on short final. Obviously Vso changes with weight and CG, but the plane should settle nicely at that speed. I really think most fly way too fast. From my experience, limited as it may be, it is pretty easy to maintain a nice stabilized approach with a bit of throttle when needed and of course pitching for air speed

In my airplane 1.1 VSO is real close to 45kts at the weights I do this kind of flying. For me the difference is the BH glides like a lead brick when compared to what I'm used to and it is heavier. This means the ground comes up faster and it takes more energy to arrest the decent. I'm getting used to it and feel like things are coming together. Now I need to resist the "good enough" urge that come from knowing a 400ft takeoff and 350ft landing will take me anywhere I'm wanting to go.

[Nev]

I've definitely found the same thing. The Bearhawk doesn't land like most other aircraft at the higher flap settings, which is great for STOL but it's taking me time to get accustomed to.

[Nev]

This is a very interesting discussion.

I'm flying my approaches very similar to Whee (and John Bickham) - 50 kts IAS works well for my stage. I've flown a couple of approaches at around 45 kts, but in hindsight I think my safety margin was uncomfortably low. During the test flying phase I decided to raise my approach speeds back to 50kts. Obviously there's a higher chance of an engine issue during these early flights and I didn't want to discover one with F4 and a low speed that I couldn't recover from and still make the runway.

Also there aren't many B model Bearhawks flying yet, at least not in the same numbers as the A model.

The B model differences are: 4 stages of flap, larger flaps, a different wing profile, increased wing area, and the leading edge datum may have changed a small amount, giving CG numbers that may not compare directly. The point in my mind is that while I was lucky to get some flying practice on a couple of other Bearhawks (huge thanks to Battson and others), there are enough differences that I don't feel comfortable going straight to a high AOA approach on mine because there are too many unknowns.

Currently I don't know how much position error I have, and how much position error is present on other Bearhawks when we compare approach speeds.
The majority of my landings have been done at light weight and forward CG. However I've got the additional weight of an IO540 and 3 blade prop, so "lightweight" for me is roughly 200lbs heavier than a similar airframe with an IO360, most of the weight difference being on the nose. Someone with an IO360 will see a (real) stall speed lower than mine due to the weight difference, and an even lower stall speed perhaps due to a more favourable (aft) CG and therefore increased position error so that the IAS displays a significantly lower speed. In other words, the IAS that we're comparing between our individual aircraft is what we're reading from our screens, but I'm not sure yet if we're talking the same CAS. There could be significant differences, hence I'm exercising caution when comparing approach speeds.

My initial stalls showed 38kts at F3 & F4 (power on) and 41kts (power off), so (coincidentally) my approach speed of 50kts equates to 1.2 VS. This is what we used to teach in a previous life for a generic short landing technique. The Bearhawk flap limit speed for F4 is 55kts, so it becomes quite difficult to fly a F4 approach at 50kts with only a 5kt margin, particularly with any gusts. The other thing I've found consistently with F4 is how easy it is to get a very high sink rate going (due to the added drag and already being on the back of the drag curve), and it happens quickly. So I've been flying with a small amount of power on until ready to touch down. When I reduce the power to idle, the aircraft stops flying almost immediately, whether the ground is there or not.

This all makes sense because even at 50 kts, I'm flying on the back of the drag curve. (The concord from memory did the same thing - though not sure why I just added that). Obviously speed control becomes more demanding because on the back of the drag curve, speed is no longer stable. (A small decrease in IAS increases drag, and further reduces IAS v.v.). I'm reluctant at this stage to move further up the back of the drag curve because I'm certain it'll get a lot more exciting, and quickly. But I also think the STOL landing capability of the Bearhawk doesn't necessarily depend on how close I can fly to the stall speed, but from the ability to fly easily on the back of the drag curve - hence the huge flaps.

At F3, I'm finding I have a little more margin all round. The F3 limit speed is 65kts, so I now have a 15kt buffer. I can select F3 turning finals and it's done. Because there's slightly less drag, the speed control is easier and more stable. And when I reduce power to idle, it seems slightly more forgiving.

All of this still equates to very short landings. I don't know how short, but definitely much shorter than anything I've flown before, and I'm not really using a lot of braking yet either. Anyway, hope this explains why I'm being conservative at this stage.

Feel free to add comment and thoughts, and critique my logic too. It's a very interesting discussion.

[Gerhard Rieger]

Great explanation for me who are getting closer to my first flight. Lot to learn

[Battson]

Minor technicality, both models have the same number of notches of flap.

I also think it's worthwhile being clear whether we are talking KIAS, KTAS, or GS - and the weight. There can be a meaningful difference.

[zkelley2]

If F3 & F4 give the same stall speed, then F4 is drag only and no lift. The only use it has at that point is to steepen the approach, should you actually need that. I find I rarely need very steep approaches due to obstacles.
If you're uncomfortable with the 5kt margin, just use Flaps 3. In gusts, this is a common thing. We even run into it on the 74. Ref speed will commonly be in the 160s, with wind gust additive, you end up in the 170's. Flaps 30 limit is 180. Having 5kts to flap overspeed in gusts isn't acceptable. So we land flaps 25 with about a 5kt higher ref speed.

Also, just about everything I've flown bigger than a 172 or cub requires power all the way to the flare, or even into touchdown. From a 206 to the 74, it's power on. This is normal for aircraft with utility.

[Gerhard Rieger]

On the Bearhawk Aircraft page there are a couple of good reports from professionals bush pilots about landing technique.

http://bearhawk.wpengine.com/?attachment_id=3125

[Nev]

That's very interesting to listen to. They were using the same numbers. I was interested to hear how they were managing risk - around the 9:00 mark.

[whee]

On the Bearhawk Aircraft page there are a couple of good reports from professionals bush pilots about landing technique.
http://bearhawk.wpengine.com/?attachment_id=3125

Good stuff, thanks for posting that link. What he is describing is exactly what I'm trying to accomplish. I just need to figure out the "pitch" portion at the end.

My airplane is rock solid at 50kts and 4 notches of flaps (50deg). Once I figure out how to arrest the descent at touchdown I'm confident I could slow the airplane down a fair amount more. But what's the point if I'm already landing shorter than I can takeoff.

My takeoff is pretty much as he describes. I know for sure when I was on 850x6 tires my EFIS would show real close to 36mph as the wheels broke the ground. I'm on 31s now and when I tried to glance at the ASI during the takeoffs to note the speed at which the mains left the ASI was not indicating anything. More data needs to be collected to know if that was a fluke.

[Battson]

In my airplane 1.1 VSO is real close to 45kts at the weights I do this kind of flying. For me the difference is the BH glides like a lead brick when compared to what I'm used to and it is heavier. This means the ground comes up faster and it takes more energy to arrest the decent. I'm getting used to it and feel like things are coming together. Now I need to resist the "good enough" urge that come from knowing a 400ft takeoff and 350ft landing will take me anywhere I'm wanting to go.

Hold the phone -

Attitude controls airspeed, power controls descent rate.

If you are descending too fast, add power.

If you are dropping below 1.1 Vso, lower the nose.

Being at 1.1 Vso has nothing to do with descent rate, provided you are still above stall speed. You should be able to slam it on, or kiss it on, at any airspeed above the stall.

Edit to add, general comments not specific to you Whee -
During a stabilised approach, on any day except a gusty one, airspeed control should be within 2kts, it does not take lots of active control - you just have to set the aircraft up correctly with trim and power. More flap makes this easier, as it is possible to use more power - larger forces make the system more robust, and less easily upset by small outside changes - such as wind or control stick inputs. With less drag, you have less power - resulting in a finely balanced system. This means you have a smaller window to fly in, to avoid accelerating unintentionally.

If flying within 5kts proves difficult on a stabilised approach, then it would be worth doing more practice at stabilised approaches before flying at 1.1 Vso. Flying with full flap at 50 knots for instance, this does not take much work - just set the plane up correctly. A higher stall speed means a heavier Bearhawk, so you have more momentum and the airspeed and vertical speed should be nice and steady.

[whee]

Hold the phone -

Attitude controls airspeed, power controls descent rate.

If you are descending too fast, add power.

If you are dropping below 1.1 Vso, lower the nose.

Being at 1.1 Vso has nothing to do with descent rate, provided you are still above stall speed. You should be able to slam it on, or kiss it on, at any airspeed above the stall.

Edit to add, on a stabilised approach on any day except a gusty one, airspeed control should be within 2kts, it does not take lots of active control - you just have to set the aircraft up correctly with trim and power. More flap makes this easier, as you have more of a power range to play with. With less drag, you have a smaller power window to avoid accelerating unintentionally. If you are having trouble keeping it within 5kts, then it would be worth doing more practice before flying at 1.1 Vso

I'm struggling to find the right words to explain what I'm doing/thinking here but I'll give it a try anyway.

During the flair phase of landing the flair is used to use up the excess airspeed (energy, zoom reserve, or whatever you want to call it) and slow the decent rate. Too much excess airspeed and the plane floats, flair too fast with too much energy and the plane balloons, not enough energy or not enough pitch increase and the decent rate stays too high so the plane slams into the ground. Say you come it at 1.1 Vso, this means you have .1 Vso units of excess airspeed that needs be used before the plane touches down at the perfect airspeed. Ideally that excess speed is exactly the amount of energy required to arrest the decent when you pull back on the stick. Your trading airspeed for altitude...but instead of gaining altitude your stopping the decent. No engine power used.

I prefer to avoid adding a blip of throttle in the flair because even though that blip arrests the decent it also adds forward speed. Minimizing forward speed is what we are really after for short landings. I fully recognize that flying a slower approach that requires a blip of power in the flair might be the best way to gain max performance in a Bearhawk.

If I were to execute what I currently perceive as a perfect approach and landing: I'd fly a stabilized approach at a minimum airspeed that has exactly enough excess energy to arrest the decent without requiring any engine power to arrest the decent. Based on my current experience 1.1 Vso has enough excess energy to arrest the decent if you do it right. Even slower is doable but it requires a better pilot than me.

[Nev]

Another data point or two from todays flying. I did quite a few stalls both into wind, and downwind, then downloaded the data and averaged the groundspeed to establish position error. It looks like my power off stall speed is around 39-40 kts IAS with about 2 kts position error at 3000 ft with ambient conditions being very close to ISA, and ballasted to about 15" CG at 2000lbs . (I used average groundspeed and TAS to compare with indicated stall speed).

The elevator broke first most of the time. If I do them power on, I can get back to 38 kts IAS (40 kts TAS) and fly at that speed in a reasonably controlled manner, though there's a fairly defined break from the power on stalls with the nose pitching down, but no wing drop so far.

I then downloaded the data from 15 approaches, which showed 10 with an approach speed of 50-52kts IAS, and 5 approaches at 55kts IAS (when the winds increased). The average speed at 10 ft was 42 kts IAS and average touchdown speed from all approaches was 35 kts IAS. The speed reduction from 50 kts was occurring in the final few feet, with no float, it's all happening rather quickly.

At this stage I'm having to keep power on almost until touchdown, and often a small burst at the end. I noticed too that I'm giving the occasional burst during final approach and I assume that it's because of the speed instability on this part of the drag curve. None of them are smooth or even close to it. I'll settle for consistency if I can achieve it, but even that's a struggle right now! Anyway, I need tons more practice.

[Gerhard Rieger]

https://youtu.be/cTHUjmC128s

look and listen to this youtube video of MAF bush pilots flying behind the drag curve using pitch for speed and power for altitude on a stabilised approach all the way to touch down

[Battson]

I'm struggling to find the right words to explain what I'm doing/thinking here but I'll give it a try anyway.

During the flair phase of landing the flair is used to use up the excess airspeed (energy, zoom reserve, or whatever you want to call it) and slow the decent rate. Too much excess airspeed and the plane floats, flair too fast with too much energy and the plane balloons, not enough energy or not enough pitch increase and the decent rate stays too high so the plane slams into the ground. Say you come it at 1.1 Vso, this means you have .1 Vso units of excess airspeed that needs be used before the plane touches down at the perfect airspeed. Ideally that excess speed is exactly the amount of energy required to arrest the decent when you pull back on the stick. Your trading airspeed for altitude...but instead of gaining altitude your stopping the decent. No engine power used.

I prefer to avoid adding a blip of throttle in the flair because even though that blip arrests the decent it also adds forward speed. Minimizing forward speed is what we are really after for short landings. I fully recognize that flying a slower approach that requires a blip of power in the flair might be the best way to gain max performance in a Bearhawk.

If I were to execute what I currently perceive as a perfect approach and landing: I'd fly a stabilized approach at a minimum airspeed that has exactly enough excess energy to arrest the decent without requiring any engine power to arrest the decent. Based on my current experience 1.1 Vso has enough excess energy to arrest the decent if you do it right. Even slower is doable but it requires a better pilot than me.

In case it's interesting, when I am going for absolute max performance I use a slightly shallower approach and just let the plane 'flop' onto the ground, the opposite of a flair. No blip of power. Close the throttle and release back pressure on the stick from about 1ft up.... let the gear legs and bushwheels do their thing. Brakes applied as it touches down. That only works when the plane is very light, when it's heavy it's necessary to finesse it on.