Neville's Bearhawk

Flying the Bearhawk - Approach and Landing

These notes are no substitute for getting good tail-dragger instruction from an experienced instructor or an experienced Bearhawk pilot.

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 others with more experience, from the forums, or simply from hours of practice and finding first what doesn't work, before finding what does work and learning the eccentricity's of a capable STOL taildragger.

The notes pertain specifically to my own aircraft with an IO540, VG's, a 3-bladed composite prop, empty weight of 1500lbs 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

The Bearhawk lands very easily. For the first few flights, I kept my CG around 15", 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.

For the touchdown, I simply kept the aircraft flying in ground effect as for a normal landing on any small aircraft, touching down at the lowest possible speed and in a 3-point attitude.

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 to calculate IAS position error (in my previous blog article) and of course stall speed.

Lowering risk

Particularly on the early flights when my tailwheel experience was low and I was new to the aircraft, I chose to fly only on relatively fine days with light winds, on into wind runways.

I also decided to use very little braking early on, only using enough to assist with steering when required, but by using long grass runways for landing, no braking was required to stop.

The first few flights were at light weights, ballasted to a mid CG. Later, many of the test flights were conducted at mid to higher weights, for two reasons. I chose to initially fly with a minimum of 100 liters (25 gallons) to reduce the chance of unporting a tank if flying out of balance. This proved to be a good idea as it took me about 20 hours before I was flying in balance consistently. Secondly, many of the test flights are conducted at higher weights to test the full weight and CG range. For this reason I always used a minimum approach speed of 50KIAS, and often 55KIAS, reducing to minimum speed in ground effect before touching down.

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. 

Elevator authority

Like many STOL aircraft the Bearhawk tends to lose elevator authority at very low speeds and 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 and I get too high on an approach.

With just myself and say half fuel, the CG on my Bearhawk is typically about 12.5", 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. The solution is to keep airflow (propwash) over the elevators, but that requires keeping power on. I'm now comfortable with it. The obvious work around is to throw some gear 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. Early indications are that the 4-place B model CG may be forward of the A model (all else being equal).

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 and I use it on every flight. It can be calibrated by flying a series of stalls. Mine is set to begin a slow beeping at 55kts, wings level and 2300lbs approximately. At 40 KIAS (39 KTAS) it sounds a continuous tone. My stall speed in this configuration is 38KIAS (37KTAS) 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.

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 will 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 reduced 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.

STOL Approache 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 alot 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 to reduce any tendency to nose over under heavy braking. 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.

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 retrim becomes less). This sensitivity is more noticeable in the takeoff and cruise. I chose to limit my aft CG practically to 21".

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.

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 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.

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. Touching down a few knots faster fixes the issue. However one benefit of landing tailwheel first is that it immediately reduces the AOA and tends to stay on the ground.

Reasons for doing a (tail-low) wheeler in a Bearhawk are that it keeps the tail clear of the rocks, increases visibility over the nose, allows the large main wheel shock struts to soak up the bumps, and keeps the CG aft.

Short Landings

Once I had a few hundred landings under my belt I began to focus a lot more on STOL approach and landing technique, for when the runway length is more critical.

I made sure to test for IAS position error before trying these. I also kept my IAS on final approach above 50kts IAS. 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).

After flying around 450 landings I flew a series of short landings with the final approach speed of 45 KIAS. To get back to this speed I had 60 liters of fuel and 1 POB, giving an AUW of 1850 lbs. The resulting touchdown speeds were very similar to when I used a slightly higher approach speed (but reduced speed in the flare). This seems to be because once power is removed and the pitch attitude increased, the airspeed reduces very quickly. At this stage I plan to keep using 50 KIAS for most STOL approaches.

The setup

To setup for a STOL approach, I reduce engine power until airspeed begins to reduce in level flight - this requires raising the nose as the speed decreases. At 75kts I select F2, and then F3 at 65kts. When the prop spinner is just touching the horizon I start a descent, while holding the spinner on the horizon. This puts the AOA in the right place. On final approach I select F4 and maintain an approach speed of 50 KIAS (48 KTAS).

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

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 push forward to roll onto the mains. As the aircraft touches down, the airspeed is decreasing rapidly.

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 forgiving grass runway, and finally getting instruction from others, I was able to start getting the technique more consistent.

I'm now able to land using the above technique fairly consistently, and the landing roll length is similar to a 3-point landing (120-150m comfortably). I'm now working on modulating the brakes to help hold the tail just off the ground as the aircraft slows.

Landing distances

With just the pilot and half fuel (1900lbs) the Bearhawk lands in about 100m. That's not accounting for obstacles, wind etc. But if you have a clear approach and fly at minimum speed on short finals, that's about what the ground roll will be. My Bearhawk uses approximately the same distance for takeoff as it does for landing.

I've experimented with various approach speeds at weights below 2200lbs. Any TAS below 50KTAS results in a reasonably short ground roll. At a final approach speed of 45KTAS, I can still get the main wheels to touch first. However below 45KTAS, the tailwheel nearly always touches first resulting in a heavier landing.

Here are some sample landings showing the weights and distances. The landings with one POB were measured. The others were estimated. I didn't log wind and mostly it was light and variable, but there a few days when I had a crosswind of 8-10kts.

My normal final approach speed is 50KIAS when the aircraft is light. However I've shown TAS on very short finals below. I'm able to download this from the Dynon HDX. From that data I can see that I tend to maintain roughly 50kts down to the last 200ft. Below that I'm tending to reduce speed to what is shown below.

High descent rate

Using this technique can easily lead to a high rate of descent. 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

About half of my short 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 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. I've now become comfortable with the sensation and I simply continue with the landing.

I've practiced all sorts of landing recoveries on a long wide grass runway. One issue is that if you botch an approach or landing, normally it's a good idea to go-around. However I also realized that quite a number of the backcountry airstrips don't permit a go-around, so it's good to get used to a variety of landings and what can be considered normal.

Backcountry Airstrips

I'm still very new at this, but I've landed at a number of back country airstrips, typically around 250-300m, narrow and often rough. Landing short is not an issue. Once the above technique is practiced it's quite comfortable.

The main issue is actually the width of the airstrip and maintaining directional control. Often it's critical to stay in the wheel ruts from preceding aircraft to avoid hidden rocks/holes in the long grass.

I would highly recommend flying into some airstrips with another experienced pilot first, once having practiced the above techniques. 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.

This post is from Neville's Bearhawk