Bearhawk Stall Speeds

[LukeS]

Wow! I would say unbelievable, but I just watched the video. That's some serious "pucker factor" STOL performance. I would never have thought the four-place could fly so slow. Thanks for the video.

[Battson]

Flying very lightly loaded yesterday, although not extraordinarily light, I was able to keep flying with full control at down to 29-30 KIAS. I was very surprised as I was sure 33kts was the limit. I have cockpit video proof too

I practiced a number of approaches and touchdowns at this speed, the weather was perfectly still making such speeds possible near the ground. It certainly makes a difference compared to carrying a my usual safety margin. It would be possible to land a much smaller spot at that speed, but of course there is no room for error and weather needs to be dead calm.

Unbeknownst to me, I was being filmed from the ground and I happened upon the video by chance:

[Battson]

Thanks for the kind words. I am using the STOLspeed VGs, which just adhere with a simple 3M sticker. You install over the paint, this is more than strong enough even with my crumby paint.
The VGs are also kinda flexible and have rounded edges, which helps if you ever had to refuel without a step ladder.
The important part is the distance from the LE, to ensure they are fully exposed to the airflow when the wing is at the stall AoA. There is a thread on here which discusses this location, a Google search including "site:bearhawkforums.com" will find it.

[LukeS]

So, sorry for the Spanish inquisition here, but do you remember which VGs you went with? Also is it preferred to install them before painting so they're stuck to the metal instead of just held on by whatever bond strength the paint has? I think I've been watching your youtube (whosaidyoucandance?) videos, and the performance is pretty impressive. If these are yours, thanks for posting them. They're great motivation.

[Battson]

Our stall speed reduced about 3 kts, but the approach speed came down a lot more. Probably 5-8 kts while maintaining the same AoA margin above the stall.
They were definitely worthwhile for the kind of flying I do.

The benefits are heavily dependent on getting the placement right. Some BH pilots have installed VGs and seen no measurable improvement.

[LukeS]

Do you know what your stall speeds were before adding the VGs? Were they worthwhile in your opinion?

[jaredyates]

If you fly three courses 90 degrees apart and record gps groundspeeds for each, it is a matter of math to determine the error.

[Battson]

When the GPS says 50kts GS and the ASI says 50 KTAS coincidentially, same again at 45kts etc, as you approach the stall, you can reasonably assume the GS is giving you a consistent reading with the ASI. Good enough for my purposes anyway. In my machine, they start to diverge below 45kts as the AoA gets larger.

My avionics are constantly monitoring the wind in the same way, which it displays on screen.

PS. For me, the last ~5 kts between the stall buzzer kicking in and the actual onset of the stall is the "expert zone" for approach speeds. I rarely venture into that region, unless I am really forced into pushing the limits for some reason - which only happens on a perfect weather day when I am very, very current.

[Zzz]

We have confirmed with GPS and we see anywhere from 33* kts to 42 kts depending on the weight. *we have vortex generators installed

Our usual final speed is 40KIAS with 2 pax and 50% fuel, touchdown about 35-ish I guess, but I am never looking.

How do you ensure totally calm winds when you do this? That seems like a huge error/unknown when making airspeed measurements with a ground speed tool. Do you do it in multiple directions and average?

[alaskabearhawk]

Thanks guys! This gives me what I need to go forward.

[Battson]

We have confirmed with GPS and we see anywhere from 33* kts to 42 kts depending on the weight. *we have vortex generators installed

Our usual final speed is 40KIAS with 2 pax and 50% fuel, touchdown about 35-ish I guess, but I am never looking.

[jaredyates]

I think this may be one of those "measure with a micrometer, cut with an ax" situations. At such low speeds, the ASI is not going to be very accurate, and if things are going right, you aren't going to be looking at it anyway!

[Enewton57]

Of course each airplane will vary according to weight, rigging, etc. but my O-360 equipped Bearhawk, weighing 1300 lbs stalled as follows: Clean = 50 MPH IAS 15 degrees flaps = 50 MPH IAS 25 degrees flaps = 48 MPH IAS 40 degrees flaps = 45 MPH IAS

[alaskabearhawk]

I got an airspeed indicator off ebay and plan on sending it off to be overhauled. Part of the overhaul will include putting custom markings on the face to reflect the Bearhawk speeds. I was looking through old emails and what Russ Erb had put on his airspeed indicator. The full-flap stall speed (bottom of the white arc) is 45MPH/39KTS. The clean, no flap stall speed (bottom of the green arc) is also 45MPH/39KTS. Is this true? It seems the full flap stall speed should be less than the clean stall speed. Any insights?