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Approach and Landing


These notes are no substitute for getting good taildragger instruction from an experienced instructor.


There wasn't a lot written initially about how to fly the Bearhawk and so most of what I've written below is gleaned from hours of practice, the experience of others, or simply finding first what doesn't work, before finding then what does work and learning the eccentricity's of a capable STOL taildragger.


These notes pertain specifically to my own aircraft with an IO540, VG's, a 3-bladed composite prop, empty weight of 1508 lbs and empty CG of 8.3 inches. Position error is measured at a maximum of 3 kts at 50 KIAS and 1 kt at 40 KIAS (where 40 KIAS = 39 KTAS).



First landings

For the first few flights during test flying, I kept my CG around 15", a minimum of half fuel, and used Flap 2 with an approach speed of 60kts. The mid range CG meant that I had full elevator authority, and not too sensitive on the rudder.


An approach speed of 60kts kept me well above the stall, and the reduced flap setting meant I could select F2 at 75kts and not think about it again. I would then to do a normal flare in ground effect (with a trickle of power still on) while the speed reduced, to touch down at minimum speed in a 3-point attitude. This technique was simple and works well on longer smooth grass runways.


Later, when I had many more hours up my sleeve, I wanted to explore the envelope with shorter landings. Before doing this it's a good idea do a number of stalls to establish stall speed.


Vortex Generators

My Bearhawk has VG's installed on the main wings. They don't change my power on stall speed, but they do reduce the power off stall speed by 4 knots and improve the slow speed handling. I've also installed VG's under the tailplane. The effect of these on elevator authority is similar to moving the CG 1" aft. If I did this again I probably wouldn't install the VG's under the tailplane, but I would definitely install them on the main wing.


Elevator authority

Like many STOL aircraft the Bearhawk tends to lose elevator authority at very low speeds when at a forward CG, specifically when the CG is forward of 14", and below 50kts TAS. It's most noticeable when I'm practicing circuits by myself if get too high on an approach.


With just myself and half fuel, the CG on my Bearhawk is typically about 13.5", and when I reduce engine power to descend at 50kts, after a few seconds the nose starts to drop. It's self correcting - as it descends it gains airspeed, and I can lift the nose again, but there is a tradeoff in height. The solution is to keep airflow (propwash) over the elevators, but that requires keeping power on. It can take a while to become comfortable with it. The obvious work around is to throw some gear (tools and survival kit) in the cargo area to move the CG aft to mid-point. In addition, if I get too high I now raise the nose even further to increase the descent angle.


Many Bearhawks have an empty CG that is well aft of mine (it's dependent on the individual build) such that it's unlikely that they'd be forward of 14" anyway.


AOA Audible Beeper

I have the Dynon Pitot installed with an AOA indicator. It has a visual presentation on the PFD (I've never watched it in flight) and an audio beeper that sounds in the headset. The beeper is brilliant. It can be calibrated by flying a series of stalls. Mine is set to begin a slow beeping at 50 KIAS, wings level and 2200lbs approximately. At 40 KIAS (39 KTAS) it sounds a continuous tone. My stall speed in this configuration is 38 KIAS (37 KTAS) with power on.


The great thing with the AOA beeper is that it measures AOA rather than speed. Therefore if I do a steep turn, it could for example start beeping at 70kts, indicating that we're getting close to the critical AOA as the stall speed is increasing under load. After alot of practice you become used to the pitch angle on approach, and even if the AOA beeper isn't working you tend to fly on AOA simply by looking at the engine cowling in relation to the horizon - usually you don't even notice that you're doing it. It's simply the "muscle memory" from alot of practice.


Engine power on approach

The Bearhawk being a good STOL aircraft, isn't known for it's glide ability. Anytime that power is reduced to idle at approach speeds below 60kts with flap deployed, a high descent rate may develop. This can then be arrested by re-applying power. It can be reduced by increasing airspeed, but this requires several hundred feet of altitude. At low altitudes this may not be possible.


Its worth noting that keeping power on at low speeds contributes to a "Blown Flap" effect, and reduces the stall speed on mine by 7 KIAS before the installation of VG's and 3kts with VG's


All my approaches are flown with some power on.




Risk

I spent a lot of time considering what level of risk I was willing to accept. When flying a STOL approach, in the event of an engine failure:


- the approach angle will steepen considerably

- the descent rate will increase considerably

- the stall speed will rise by several knots.


In short, I'm reliant on the engine and its reliability during the last several hundred feet. This is not specific to the Bearhawk. If the engine stops while at low speed with a lot of flap out, the outcome may not be easily recoverable. For that reason I tend to carry a slightly higher airspeed and F3 when a STOL approach isn't necessary, for a "normal" landing.


Effect of CG

Keeping the tail low (but just off the ground) ensures that the CG remains comfortably aft of the main wheels during the landing roll, to reduce any tendency to nose over under heavy braking. This is largely due to the weight of the fuel in the fuel tanks remaining behind the CG.


A good illustration of this is to see how hard it is to lift the tail off the ground. It takes two people to lift mine. However once the tail is overhead it is easy to hold it there with one outstretched arm because the CG has moved forward over the main wheels. In this attitude it would be very easy to apply too much brake and override the correcting down force of the elevators as the speed reduces.


As mentioned above, the Bearhawk maintains full elevator authority when the CG is aft of 14". When the CG is aft of 20" the pitch control becomes increasingly sensitive, (and the need to re-trim in pitch becomes less). This sensitivity is more noticeable in the takeoff and cruise.


The rudder also becomes increasingly sensitive inflight (demands more attention) as the CG moves aft. This is also noticeable on landing with an aft CG at heavier weights.

For this reason I keep the CG forward of 18" and the landing weight below 2300lbs when landing on shorter airstrips to stack the deck in my favor.


Flap usage

The F4 limit speed (55 KIAS) can be restrictive, particularly above 2300lbs landing weight. However it's also best practice to touch down as slow as possible (minimizes risk of ground loop). Practically, there's no noticeable change in stall speed between F3 and F4, just an increase in drag that requires an accompanying increase in engine RPM to balance it. The increased RPM helps to keep airflow over the elevators for increased elevator authority, and additionally increases airflow over the flaps.


As a very general rule of thumb, I tend to use F3 on longer grass runways when carrying more than 2 POB (2300 lbs), and F4 on shorter backcountry airstrips.


Normal Landings

At weights above 2300lbs when runway length is sufficient I find it much easier to fly an approach at F3 and 55-60kts, and wheel the aircraft on in ground effect with the tail low. It uses more runway (200-250m comfortably), but it's much gentler on the airframe. It's still a fairly short landing. The actual technique here is to still flare into the 3-point attitude, then ease the stick forward and roll the main wheels on. The main difference is to carry a few extra knots on final approach, F3, and leave a little more power on into the flare.


A 3-point landing also works very well, but it can be harder on the airframe. The Bearhawk can very easily touchdown tailwheel first when very slow due to its high AOA, and many of my early landings were like this. I didn't like the fact that it transmits the stress right through the fuselage. Once again, keeping a trickle of power on helps. However one benefit of landing tailwheel first is that it immediately reduces the AOA and tends to stay on the ground.


Short Landings

When the runway length is more critical most pilots fly a specific backcountry STOL approach and landing.


When operating into short airstrips it is normal to keep the aircraft weight low. I use 2200lbs or less as a rule of thumb when landing length is approximately 250-300m.


Be sure to test for IAS position error before comparing airspeeds with other aircraft.


I fly a normal approach at normal speeds until final approach. I then target an IAS on final approach of 50kts KTAS or higher until on short finals. Because this places the aircraft on the back part of the drag curve, raising the pitch attitude for the flare very quickly dissipates remaining speed and energy, and the touchdown is normally around 38-40 KIAS (37-39KTAS).



The setup

Flying with an instructor is the best way to learn.


One way to practice the setup for a STOL approach is to reduce engine power in level flight until airspeed begins to reduce - this requires raising the nose as the speed decreases. At 75kt select F2, and then F3 at 65kts. When the prop spinner is just touching the horizon, start a descent, while holding the spinner visually on the horizon. This puts the AOA in approximately the right place for the approach. On final approach select F4 and maintain an approach speed of 50 KTAS. The aircraft nose can be lowered slightly to touch the spinner on the aim point for better visibility, or it can be kept on the horizon.


In this attitude if the nose is raised further the aircraft will descend at a steeper angle.


The touchdown attitude is similar to the 3-point attitude when the aircraft is parked on the ground. The transition from the approach attitude to the touchdown attitude is a minimal change, and may require a small increase in power. Once the wheels touch, the power can be reduced to idle.


Landing

Visibility over the nose is a definite issue. Once I'm on short finals I sit up high in my seat and place the spinner visually about one aircraft length short of the threshold. Alternatively I can keep the nose on the horizon and look along the left of the engine cowling, but I find that more difficult.


As I enter the flare the TAS has typically reduced to around 45 kts (in the last few seconds) and I increase the power momentarily to reduce the descent rate, flare, and immediately ease the control stick forward to roll onto the mains. The sensation of getting the correct flare attitude, is one of gently dragging the tailwheel onto the ground just before the mains touch. As the wheels touch, move the control stick gently forward to lift the tailwheel slightly off the ground. In this attitude you will just be able to see the airstrip over the engine cowling.



A small amount of power is left on right up until the main wheels touch down.


An easier way to learn the technique is to simply land in the 3-point attitude, then ease the control stick forward to bring the tailwheel just off the ground. Once familiar with that, then I eased the control stick forward right when it feels like the tailwheel is about to touchdown first.


My early attempts at getting this right were demoralizing. It took many approaches finally get one right. I was then unable to repeat it. After many hours of flying low level circuits on a long grass runway, and getting instruction from others, I was able to start getting the technique more consistent.


With practice using the above technique, the landing roll length is similar to a 3-point landing (120-150m comfortably and often less). Brakes can be used carefully if needed.

Photo by Geoff Soper


High descent rate

Using the technique above can easily lead to a high rate of descent if the power is reduced to idle. It didn't take long to get used to, but it did get my attention a few times. The trick is to keep power on, and if you do need to lose height quickly, keep the nose high and reduce power a small amount but be ready to re-apply power when needed.


Side-Slip

The Bearhawk has been designed with a large amount of rudder authority to allow easy side-slipping.


Bounced landing

Alot of STOL Bearhawk landings feel like they have a bounce (skip) right after the touchdown as the aircraft comes up on the main wheels and the AOA reduces. These touchdowns are usually slightly heavier that a normal wheeler and can be quite agricultural. Interestingly in most of the videos I've watched of other STOL approaches in similar aircraft types, they can also be seen doing a similar bounce with the wheels skimming the ground and the tail rising up to just clear the ground. It doesn't take long to become comfortable with the sensation and simply continue with the landing.


One issue is that if you botch an approach or landing, normally it's a good idea to go-around. However a number of the backcountry airstrips don't permit a go-around (one way airstrips), so it's good to get used to a variety of landings and what can be considered normal.


Importance of aileron into wind

Nosewheel aircraft tend to have the fuselage side area spread evenly either side of the main wheels, so in a crosswind there is minimal tendency for the aircraft to change heading on the ground. Tailwheel aircraft however, tend to have a large fuselage surface area behind the main wheels, so any crosswind hitting the side of the fuselage will cause the aircraft to turn into wind on landing, takeoff, and taxying.


Because of this turning tendency it is very important to keep the ailerons into wind.


For example, if the crosswind is from the left, roll the control stick to the left. This will cause the left wheel to touch down first on landing, and during the landing roll the right aileron will be down, creating additional drag that helps (a lot) to counter the turning tendency of the aircraft into wind. A light crosswind can be just as difficult due to the fact that it can be hard to perceive.


Early in my tailwheel journey I became very reliant on using differential braking particularly during the landing roll, for steering. This is a very bad habit, and it increases the tendency for the aircraft to groundloop. Once I became proficient at using the flying controls I now seldom need to use differential braking on takeoff and landing, other than at very low speeds.


Backcountry Airstrips

Many back country airstrips are typically around 250-300m, narrow and often rough. Landing short is not an issue for the Bearhawk. Once the above techniques are practiced it's quite comfortable.


The main issue is often the width of the airstrip and maintaining directional control. This is all down to pilot technique and practice - the Bearhawk with it's large rudder is more than capable. Often it's critical to stay in the wheel ruts from preceding aircraft to avoid hidden rocks/holes in the long grass.



It's a good idea to fly into some airstrips with another experienced pilot first, once having practiced the above techniques on open ground. I was very lucky to have flown into a number of airstrips with another experienced Bearhawk pilot in his aircraft, then to have another experienced backcountry pilot provide some instruction for me in my own aircraft.

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