Hall Brother VG’s

[Utah-Jay]

I see most of you use StolSpeed VG’s and I did not want to hijack that thread

Chris Spira (flying Patrol and building a Companion) down in Texas used the Hall Brothers VG’s with great results so I installed them on my Companion. I used Chris’ testing data which was beyond extensive and installed them in the exact same location as he was getting some stalls in the upper 20’s in his Patrol.

I did lots of stall testing and got:

Clean: 40 mph
Flaps 2: 37 mph
Flaps 3: 38 mph I think I just gave up to be honest as I never got a stall.

At no point did I ever have a stall, I was seeing a 600-650 fpm falling leaf.

I have flysto data touching down at 32 mph (obviously in ground effect) and that was with 50.5 gallons of fuel on board. Most of my touchdown speeds have been in the 39-44 mph range, but I do believe those speeds will get lower as I become more comfortable with the new plane. Ideally I am hoping to be able to touchdown at 35-38 mph.

BTW, the Hall Brother VG’s are metal, with two fins per piece, and the base is perfectly shaped/curved for the BH wing.

Hope this might help someone.

[Have-Purple]

How far back from the leading edge did you install? Any on underside of horizontal stab?

I see his Patrol is up on Barnstormers.

[Utah-Jay]

Have-Purple

Chris put them at 8%, I followed his lead after his extensive testing.

I glued them in at a set distance from a line of rivets, I am out of town until Monday afternoon. I can get you an exact measurement next week if that helps.

Jay

[SpruceForest]

Did your install include stab VGs?

[Utah-Jay]

Did your install include stab VGs?

No, my understanding is that when the BH design incorporated the airfoil H-Stab the H-Stab VG’s did not make a difference.

I read Harry Ribblett told Bob that the new H-Stab would decrease the stall speed by 20%, hence no VG’s needed/

[rodsmith]

No, my understanding is that when the BH design incorporated the airfoil H-Stab the H-Stab VG’s did not make a difference.

I read Harry Ribblett told Bob that the new H-Stab would decrease the stall speed by 20%, hence no VG’s needed/

I have the profiled tail on my 4-place. I can tell you, VGs under the tail made a big difference on my plane. After installing them I was finally able to make full stall landings, tailwheel touching just before the mains. Prior to that it was always tail wheel low wheel landings. After installing the wing VG's, I couldn't get a stall break at flaps 3 and 4, just a high descent mush. After the tail VGs no problem getting a break. They may make a bigger difference with my heavier engine, than on the Companion.

[SpruceForest]

There are the vids from FLY-8MA that covered Hall Bros VGs on the hor stab of a Patrol... with no real improvement observed.. Just asking... interested in actual flight test to balance engineering judgment. Data trumps theory, and multiple data sets better than one data set.

[Utah-Jay]

I have the profiled tail on my 4-place. I can tell you, VGs under the tail made a big difference on my plane. After installing them I was finally able to make full stall landings, tailwheel touching just before the mains. Prior to that it was always tail wheel low wheel landings. After installing the wing VG's, I couldn't get a stall break at flaps 3 and 4, just a high descent mush. After the tail VGs no problem getting a break. They may make a bigger difference with my heavier engine, than on the Companion.

Can and have (unintentionally) touched the TW first on a couple of my very slow landings. I am really studying my data on Flysto. I have posted quite a few videos on my YouTube with the FlySto overlay either using cockpit video or google earth generated images on the website. The data from my Dynon EFIS is amazing for dialing in landings.

Edited to add: weather permitting I have a short scheduled trip to Idaho that should produce some good video and data.

[rodsmith]

I also have found FlySto so valuable in diagnosing how to improve take offs and landings, as well as some voltage regulator , and MP sender issues I had early on.

[Nev]

I have VG's under the horizontal stab too, and estimated that they make the equivalent difference of moving the CG aft about 1". I keep power on for all landings now, typically until the main wheels are on, so the airflow over the elevators helps to keep elevator authority. I'm able to touch tailwheel first by doing that. If I take the power off before touchdown at low speeds, with the IO540 and a forward CG, I can lose elevator authority and get a firm landing.

[gregc]

Keep in mind that a Companion with the pilot and 1/2 tanks has a CG pretty much in the middle of the range. (~16 with an 11.9 to 19.8 range).

[Nev]

This is a very good point.

[Utah-Jay]

How far back from the leading edge did you install? Any on underside of horizontal stab?

I see his Patrol is up on Barnstormers.

Have-Purple

In the attached photo (yes my wing is very dirty) the back side of the VG’s are 4 1/8” from the front edge of the line of rivets
IMG_7176.jpg

Hope this helps… Now I need to clean my plane