Stolspeed VG's

[Fred Williams]

Fred I recommend the std spacing. (Closer in front of the aileron)

Thanks. Member rod smith did the full length of the ailerons (67") using the 60mm spacing vs the StolSpeed recommended 15 VGs (35"). He reported better results than most. That's why I decided to ask. Thanks both for your feedback.

[500AGL]

Fred I recommend the std spacing. (Closer in front of the aileron)

[rodsmith]

I was the one that covered the length of the ailerons with the VGs at 60mm. Don't know how much that may have helped, but I am very,very happy with the performance vs no VGs.

[Fred Williams]

A question for those using StolSpeed VGs. Did you use the recommended spacing of 60mm for the first 15 inboard from the wingtip and then 90mm for the remaining to the root? I've seen one post at least that mentions using 60mm for the length of the ailerons and then 90mm for those inboard. TIA.

[huntaero]

Do you have the flat Hor stab or the curved later version?

[Battson]

That's too bad Jay, sorry to hear this news.

[Rspencer]

Ok. Not full test results for me, but some in my 4A. Went up and flew it tonight after getting all the VG’s on the wings at 3.5% chord (aligned with middle of first rivet line) and all the VG’s on the horizontal stab lower side 4” from the elevator hinge. I did 60mm spacing from wing tip to inner edge of aileron, then 90mm spacing the rest of the wing to the root. 30mm spacing on the stab as directed.

Power off, flaps 3 plane just mushed in a steady decent at 43/44 MPH with no buffet or break/stall. Added a bit of power (1300rpm) and nose rises, slowly and steadily speed decrease. Buffet and stall with a break came at 35MPH. Straight over, no wing drop, good aileron control throughout. Was able to hold 37/36 mph and fly without a stall…..but once it goes below to 35, the buffet hits and the stall is quickly after it. Prior to this flap 3 stall was 42MPH. So 7 MPH reduced. WOW.!

I did not test any other configs tonight, was short on daylight when I got up at 5pm and wanted to do some landings. I did a couple flaps 3 landings and one full flap landing. Over the fence at 50 slowing to 45, push up a touch of power and enter the flare around 45 about a foot off the runway, with speed decreasing. Smooth touchdown at about 38 MPH. It really woke up the tail too. No weight in back and me at 280 up front and on the last one my 200lb dad up front with me, easily 3 point. I actually touched the tail JUST before the mains on 2 landings. Pretty dang impressive overall!

Thanks Virgil at Bearhawk for the chord suggestion of 3-5% based on their testing and testimonials on the earlier wing. Very happy with it. And I still got a 130MPH indicated cruise at 24”/2400 @ 4500msl. Same as before on my 31” ABW’s with baby bush wheel. So no loss in cruise speed

[rodsmith]

Sorry to hear that!

[Utah-Jay]

I'm very surprised you are selling your Companion. Seems like you have been really enjoying it.

I LOVE IT!!!! A non-health life surprise hit unfortunately

[rodsmith]

I'm very surprised you are selling your Companion. Seems like you have been really enjoying it.

[Utah-Jay]

My plane weighs 1276# empty, I have never landed with less than 12 gallons, and I typically have about 30#’s of junk in the cargo area. I weigh 210 most days in flying clothes.

I land with Flaps 3 and in a 3 point attitude, I have never full stalled a landing.

My plane will not stall, the nose has never dropped, and a wing has never dipped when doing stalls. I lose the will so to speak at about 19* nose up and dropping 650 fpm doing stalls.

Sorry if my data is not in line with other BH’s, I can only tell you what my plane does.

My Companion is currently for say word of mouth, goes on Barnstormers this Sunday…. But a VERY good glider pilot is thinking of buying it and I took him up two weeks ago and he too gave up on trying to get it to stall. I add that as I am just an average pilot

[jaredyates]

I think there is more opportunity for studying these numbers. Jonathan has additional wing area at the tips, and Jay has a significant density disadvantage. I would have guessed those would be worth a few knots each, but guessing isn't worth much in these contexts.

The other thought that comes to mind is how important weight is. One fellow just completed a build and his empty weight was in line with these gross weights. He's not the only one either.

[Battson]

[USER="232"]
I would say my average weight at touchdown is about 1800#’s, that is +/- 25 of accurate.

Location of the VG’s? Further back than the StolSpeed VG’s, all the testing was done by Chris Spira who did the testing on his Patrol. Chris’ testing data is exhaustive!!!! He tested VG location by % of the cord, included aircraft weight that day. He included humidity and DA in the daily testing data. I have a copy of all of his testing somewhere.

I am not aware of an ASI error on my plane, when checking it matches really well with my GS when correcting for my typical DA of 6000’ to 8500’ depending on the time of year (temps)

Hope that helps.

Thanks for that Jay, that is very interesting.

For a long time, I assumed my own ASI error was negligible because, during a casual landing, it always is. Typically one knot or less.
What I’ve since learned, though, is that the error spikes sharply right at the very bottom end of the performance envelope. High AoA is, of course, exactly what we’re doing for these tests at the limits of performance. There really aren’t many fundamentally different pitot designs available, so I think we're all in the same boat here. But extensive testing on very calm days is the only way to know.

This ASI error is especially relevant with Bearhawk flaps. To achieve maximum lift, we must operate at quite high AoA, so when we’re talking about stall speed and the slowest possible landing, the ASI error needs to be investigated before we can fully understand the data.

From repeated testing, I’ve found my ASI error changes sharply with landing technique:

• For a normal 3‑point landing, the error is about ≤1 knot
• For typical STOL landings, it increases to 1-2 knots, but only at the very last moment before touchdown
• In more extreme test cases, using high power and very high AoA, it spikes to 5-7 knots

I can reliably indicate as low as 28 KIAS when the plane is light, but that’s clearly not the true airspeed. At first, I was very optimistic, these days I am more realistic about it. GPS checks consistently show the real speed is about 5-7 knots higher

So depending on landing style, it seems likely we’re all operating somewhere along that spectrum.

What was the absolute lightest landing weight for the data shown in that graph?
(Just pilot, minimum fuel, and the aircraft.)

Looking at the slowest speeds shown in the data - down to 29 knots (34 mph) IAS - that strikes me as unlikely at 1,800 lb for a standard Bearhawk wing with VGs. VGs certainly help, and better designs can buy you a knot or two over poorer ones - but not on the order of eight knots.

For context, in my own STOL testing with an IO‑540 four‑place (same wing and weight), I’m typically around 1,750 lb, an I have 16" extended wings both sides (32" total extension) and STOLspeed VGs right to the tips. On paper, that would make our aircraft reasonably comparable. As I say, the slowest I get is 37 GS which often reads as low as 34 KIAS or even 28 KIAS, but again - it's always 37 GS regardless of IAS.

I think for me, something around 37 kts GS is the best that wing can support at around 1,800lbs. Ultimately, it comes down to weight versus wing area.

I’d be genuinely interested in knowing what weights relate to the lowest speeds reported in that data. If there's ways to go significantly slower, I am going to investigate them.

[Utah-Jay]

Battson

I would say my average weight at touchdown is about 1800#’s, that is +/- 25 of accurate.

Location of the VG’s? Further back than the StolSpeed VG’s, all the testing was done by Chris Spira who did the testing on his Patrol. Chris’ testing data is exhaustive!!!! He tested VG location by % of the cord, included aircraft weight that day. He included humidity and DA in the daily testing data. I have a copy of all of his testing somewhere.

I am not aware of an ASI error on my plane, when checking it matches really well with my GS when correcting for my typical DA of 6000’ to 8500’ depending on the time of year (temps)

Hope that helps.

[Battson]

It would be useful to know the average ramp weight at touchdown, the ASI instrument error at touchdown, and the location of the VGs on the wing, for comparison purposes.