Making the Rear Left Window Removeable
Electric Systems Part 2 – Materials
Bearhawk Spin Testing 2022 Edition
Source: 2022 Q4 Beartracks, Grant Bisset
Several years ago, Lee Taylor put out a nice report after doing some spins in Eric Newton’s Bearhawk. A main selling point of the Bearhawk airplanes has been their generous stall characteristics, especially compared to more primitive airplanes that remain popular in backcountry applications. This was a fundamental design goal of the Bearhawk. Lee and Eric’s report resurfaced recently, and Grant Bisset from New Zealand was concerned that the testing had stopped at forward CG locations. As the CG moves aft, elevator effectiveness improves, which means that stall and spin entry characteristics change. This is true for all airplanes, and while the Bearhawk has very good stall characteristics throughout the envelope, the pitch experience will vary based on loads. For Bearhawk pilots who complete Phase 1 testing, these changes are tested and experienced with ballast. If someone purchases a Bearhawk or otherwise ends up flying one without having done the testing, it is crucial to learn these subtleties in an incremental and safe way. “Incremental” means moving the CG aft a little at a time, and increasing the weight a little at a time. It doesn’t mean loading right to the aft limit and then going up for some stalls!
The EAA has produced an excellent flight test manual, which is a great resource for Phase 1 testing and also for new owner familiarization.
Grant is a very experienced and well-trained pilot, so he knew that it wasn’t fair to make judgements about the Bearhawk ‘s spin behavior after only testing at forward CG. So he developed a testing plan to gather more data in a safe and incremental way. Here is his report:
I was keen to further explore the stall and spin characteristics of the Bearhawk 4B. I loaded mine to what I would consider to be my normal backcountry configuration. That is a weight of approx 2000lbs and CoG 19.25 inches aft of datum.
The reason for the testing was to see what would happen if a pilot was overwhelmed by startle factor and applied a delayed, incorrect, or no recovery response in the event of an emergency. The scenarios I specifically wanted to explore involved doing everything wrong, not checking forward when the aircraft stalled, not applying power to minimise height loss. These scenarios included;
1. What would happen In the event of a partial or complete power failure and for instance, trying to extend the glide and inadvertently stalling and not applying recovery inputs. I.E clean stall with partial or no power and stick held hard back.
2. In the approach configuration what would happen if you got too slow and didn’t apply correct recovery inputs.
Approach configuration on all testing was flap 3 and 11 inches MAP. The results are specific to my B model fitted with a Lycoming IO 360, VGs at 6% of chord, 31 ABWs and ABW Baby Bushwheel. The basic stall with power off and no recovery input, the stick held on the backstop, produced a soft nodding stall that would pitch the nose up and then down, and then repeat in a pitching oscillation, (importantly this demonstrated the wing was stalling and it was not just a loss of elevator authority holding the wing at a high angle of attack and mushing) the rate of descent was high but there was no tendency to drop a wing. Repeated with partial power and no corrective rudder input resulted in a slight wing drop and yaw to the right, no buffet or warning it was going to break, again holding the stick on the backstop produced a
nodding recurring stall and recovery with directional control easily maintained with rudder, the rate of descent was about 1500ft/min.
The next step was to see if the aircraft would enter a spin. To do this I intentionally did not initiate a wingdrop stall recovery but held full back stick and left the power on, this is the sort of thing you would really berate a student for!
The aircraft stalled, dropped the right wing and yawed right. With the stick held on the back stop and neutral aileron the aircraft continued a docile yaw right. By adding a little right rudder the aircraft quickly entered a spin. As soon as the pro spin control inputs were released the aircraft recovered.
My conclusion is that my 4B will stall and indeed spin in my normal operating configuration, but only if it’s abused. It is very directionally controllable in the stall with the powerful rudder enabling you to hold a heading even while the aircraft is held with the stick hard back and a continued pitching oscillation.
It will only spin with pro spin control inputs and recover quickly when they are released. In all scenarios tested, on release of back pressure on the stick the Bearhawk recovered, and with the application of power flew away from the stall with minimum height loss.
The testing I’ve done is different to the phase 1 testing I did where I stalled and did orthodox recoveries which my Bearhawk 4B also does well and predictably.
I’m satisfied that my aircraft is exhibits great controllability and predictability throughout its envelope. I haven’t flown an aircraft with better stall characteristics.