Next mod=VG's

[C5Engineer 1170]

Going to start with them on the Horizontal only as everything I've heard they are much more effective there than they are on the the wing of an Avid. I'm going with the Stolspeed VG's from a guy out of Australia. My buddy runs them on the his S-7 and they are really nice. I'll report back after the install and flight testing.

[Av8r3400 1179]

Joey, you going to put them at the hinge point or the leading edge?

[akflyer 1427]

For the elevator, they should be about an inch in front of the hinge point.

[C5Engineer 1170]

For the elevator, they should be about an inch in front of the hinge point.

Here are a few pics from the guy I got my info from.

The info I got from JG at Stolspeed is to put the front tips 4" from the hinge line at 30mm spacing for which he provided a template. I'm currently overseas on a mission but will add to this thread when I get them installed.

[akflyer 1427]

Not sure if you ever saw the vids of the tail plane icing that NASA did using the twin otter. You can search for it on youtube if you have not seen the 3 part series. If you watch that, you will get a real good idea of how air separates from the elevator and why the VG's are so effective on the under side.

for what its worth, the videos are good to watch just incase you ever find yourself icing up. I know the recovery techiques that NASA show and figured out were NOT what my instructor taught me during initial training! They are actually a little counter intuitive. Like reduce power, no flaps and slow the plane down!!!

[SuberAvid 617]

On mine, the ones on the horiz stab did more for the plane than the ones on the wing.

[C5Engineer 1170]

Well I finally got around to installing these things today. I put the tips of them at 4" from the gap between the horizontal and elevator. It's a lot of further forward than any other airplane I've seen. This was per the instructions I received via email from Stolspeed and it's also what he has published on his site so I went with it. Here's a bit of tutorial on the install.

First off because they were made for a wing they have a very slight curve and the instructions call for a slight rub on some sandpaper to flatten them out some to go on the flat surface of the stab. I used 220 and just a couple of passes.

So step one...sand sand sand, then wipe on a rag of denatured alcohol, then set aside.

Luckily the Stolspeed comes with their adhesive laser cut to fit the foot of the VG.

You have to peel the first layer off the 3M adhesive with the tip of an exacto. They come right off.

Next stick the VG to the adhesive. All of this is somewhat time consuming but not too bad. I did all of this at home in about an hour.

I used a pencil to mark out 5 or 6 marks at the 4" point. Rather than draw on my fabric I used some painters paint to make my line.

The stolspeed VG's come with two templates in the kit. The one for the stab is 30mm spacing. Once you get going with the template the actual install goes pretty quickly. I put 36 on each side. The adhesive they use is a 3M product and works well. It's fairly easy to peel one off if you don't' like the placement. Here are some pics of the install.

The sanding, cleaning, sticking station...this part is a bid tedious but not too bad.

Some shots of them installed before I pulled my tape line.

And now what you've been waiting for...well do they work??

Conditions: OAT 98 degrees Winds 10 degrees off at 7kts Field Elevation 120ft Density Altitude 3200ft Empty wt 535lbs 9 gallons of fuel on board

On my initial takeoff I did my normal thing and the first thing I noticed was the tail came up extremely quick. Climbout felt normal. I went to 3500ft msl to try and get out of the heat. During the climb the stick was farther forward than it used to be.

Once the OAT got down to 75 or so I started doing various stalls. I started with a power on and right away I noticed that there was a noticeable buffet and break which I never used to have. Not sure of the speed as I was damn near vertical.

After that I went into slow flight I was cruising easily at 45mph IAS flaps UP. Flaps down I was able to stay level at 40ish. Before anything below 45 and I was falling out of the sky.

Next was power off. Flaps up before power off stall was 44ish. After was 40 with a noticeable buffet and break once again more like a Cessna. Flaps down stall was 35-36. Overall I decreased my stall speed by 4-5mph.

After the stalls and falls I opened her up and headed back to the airfield. The stick in cruise is farther forward now than it used to be. I flew my first approach at my normal speed of about 55 on final. Pitch felt way more solid. I did a stop and go. On the go I held the brakes and shoved the stick full forward with the flaps at 15 degrees and I was able to lift the tail and hold it level without moving. I could NEVER do that before. I let off the brakes and the tail dropped some but I was able to pull it off slower for sure. On my second approach I flew it at 50 which before would work but without a lot of power I would touch TW first. 50 felt great so I tried my next one at 45 hanging on the prop which I anticipated a TW first landing and plop onto the mains which happened but it was about the same as flying an approach at 50 before.

I can't wait to get my taller gear on. With that I think I can comfortably fly an approach at 45 to get in super short.

Keep in mind these numbers are just my numbers on my indicator. As a trend I was able to fly approx 5mph slower all the way around which in the world of STOL is pretty huge. I'm happy with the results and it was pretty cheap. I think I'm gonna go ahead and put them on my wings next and try it.

I got my VG's from www.stolspeed.com He's a nice guy, the instructions are clear, and the product is nice. Sheesh I wish I could leave this thing alone.

[BryceKat 125]

Leni, you mentioned the vg's on your tail did more good than the ones on the wing. Where is your cg? My reason for asking is that i am also installing vgs from cci, which are about the same as stol speeeds. Art Biaconne, he is cci, has been helping with all of this. My cg started at about 14.5inches. I added the vgs to the horizontal and immediately noticed a difference in pitch authority. However, i still was unable to get a full stall, which Art said i need to do before adding them to my wings. Additionally, my minimum airspeed was roughly still the same, though i'm thinking it's position error at this point. I checked to make sure i was getting full up elevator of 30 degrees (i think), but i only had 25, so i fixed that, and still no full stall! So borrowing from my r/c experience, i added 5 pounds to the handles in front oh the horizontal stab. This provided more pitch authority, but still no full stall. So i added another 5# for a total of 10#. I get just barely a break, maybe a 5-10 foot stall/drop before i'm flying again. So i'm going to add 5# more to get more of a stall break that's more cessna like. Then i'm going to add vgs to the wing. Now here's the kicker, my cruise speed, same power setting/load etc, has gone from 85 mph indicated to 100 mph indicated! Which begs the question, whats the vne on a mkiv? Bryce

[C5Engineer 1170]

Bryce good information!! I know on the big jets were directed to load our cargo/fuel in a manner which gives us the most aft CG within limits. This is for fuel savings. An airplane flies more efficient with an aft cg but it's also LESS STABLE.

[BryceKat 125]

Hi Joey, she's flyin' better the more her ass weighs! She still exhibits the same stability. I had a Super Hots r/c airplane, which was a great flying plane. I wanted to see what an airplane with a WAY rearward cg flew like. So i kept adding tail weight. What i found was that yaw stability is not an issue, and at speed pitch was not that bad, of course i knew what was going on. But... when slowing down, power and down elevator had to be added as the tail would drop thus causing the nose to rise. So you wouldn't flair, you wold kind of push the nose on to the ground for landing. This was back when the 3d craze was starting. Ironically, now that i'm thinking about it, that super hots was set up with a forward cg per plans just like the Avid. Here's a video from this am. The trim will now hold 55 mph in the pattern, whereas before it could hold 67.

[akflyer 1427]

I found the same thing on mine. At 11" it was full up trim and had to hold some back pressure on the stick. At 16" I could cruise at neutral trim on the elevator. At 18" it took just a touch of down trim to hold level flight at 100 MPH indicated. I am pretty certain that my ASI is kinda like the Yamaha or Skidoo "dream-o-meter" because the GPS even in still air says I am cruising 85-90 then the ASI says 110-115. One of these days I will get off my ass and calibrate it

I was going to move the battery to the tail, but I scrapped that idea because I won't have that big battery when I go to the other engine (no electric start).

On my 35% Extra I had a tube in the tail I could slide a 1 pound weight into. For doing the IMAC competitions I liked the rock solid feel at the forward CG (alot more precision on the point rolls and snaps), but for Free Style and 3D the CG needed to be WAY back otherwise I would get ALOT or wing rocking at high alpha (harriers, rolling harriers etc).

[BryceKat 125]

Leni, hows that other engine doing? Is there a thread on it?

[akflyer 1427]

Leni, hows that other engine doing? Is there a thread on it?

It is still on the bench.. But my significant other is now indisposed of for about the next 13 months so I will have lots of time now to get back on this project instead of trying to keep her out of trouble

[LASsociety 0]

Hi all,

I have been meaning to post, but havent had a chance. My Avid is a little heavy and near the forward CG limit when I fly. (this is according to the C.G. data that came with the plane, but I haven't personally weighed the A/C to find out if the numbers are right) I have looked behind with the door off while flying and can see that the elevator it deflected up a few degrees when flying level. Also I have to hold a tiny bit of back pressure on the stick, and if I let go it starts a very gentle dive. (no pitch trim installed, trim tab only) All of this seems consistent with a nose heavy plane. I added five pounds to the tail but after calculations, it showed that it only makes roughly 1 inch of CG difference. Right now its about 12.5 inches aft datum when flying. I was suprised that the weight seemed to have almost no effect on the flying characteristics or trim. I don't seem to "run out" of elevator when landing, or have any real controllability problems, Otherwise it seems to fly really well. (I have noticed at lower speeds when I pull flaps in I need significantly more back pressure on the stick, which is a bit awkward. I end up landing zero flaps) Im just concerned about getting the trim well balanced. Also its nice not to have to hold back pressure for long periods of time. The more weight I add the lower my useful load, so I was thinking about adding the VGs to my horizontal to see if that helps. Seems like this might provide more total downforce at high elevator deflections, but nearly nothing for cruise trim? I guess nothing will actually correct it but adding more weight to the tail, but that will start to cut into my ability to carry a passenger. Just curious about your thoughts and observations from the work you have all done so far. What normal cg range is are all of your planes when loaded for flight? If I add pitch trim, how do you all have the control set up in the cockpit for simplicity and where did you find room for it?

Thanks in advance

I think my airspeed is very accurate because when I bought it the static source was the cockpit. I found that the air disturbances around the cockpit gave innacurate airspeed indications due to venturi effect around the cockpit giving an atrificially high pitot to static comparison. .01 PSI is equal to 60 MPH of airspeed indication (thats right .01!) So I added a pitot static mast in the original pitot location so the pitot static comparison is taken at the exact sxame location. There should be no total dynamic pressure variations at different locations since they are one and the same now. It is a bit difficult to fully stall (which adds fuel to the nose heavy scenario) but when I stall its around 35 MPH indicated.

Im really happy with my Avid so far and have been having lots of fun. Looking forward to your inputs.

Mike

[C5Engineer 1170]

Hi all,

I have been meaning to post, but havent had a chance. My Avid is a little heavy and near the forward CG limit when I fly. (this is according to the C.G. data that came with the plane, but I haven't personally weighed the A/C to find out if the numbers are right) I have looked behind with the door off while flying and can see that the elevator it deflected up a few degrees when flying level. Also I have to hold a tiny bit of back pressure on the stick, and if I let go it starts a very gentle dive. (no pitch trim installed, trim tab only) All of this seems consistent with a nose heavy plane. I added five pounds to the tail but after calculations, it showed that it only makes roughly 1 inch of CG difference. Right now its about 12.5 inches aft datum when flying. I was suprised that the weight seemed to have almost no effect on the flying characteristics or trim. I don't seem to "run out" of elevator when landing, or have any real controllability problems, Otherwise it seems to fly really well. (I have noticed at lower speeds when I pull flaps in I need significantly more back pressure on the stick, which is a bit awkward. I end up landing zero flaps) Im just concerned about getting the trim well balanced. Also its nice not to have to hold back pressure for long periods of time. The more weight I add the lower my useful load, so I was thinking about adding the VGs to my horizontal to see if that helps. Seems like this might provide more total downforce at high elevator deflections, but nearly nothing for cruise trim? I guess nothing will actually correct it but adding more weight to the tail, but that will start to cut into my ability to carry a passenger. Just curious about your thoughts and observations from the work you have all done so far. What normal cg range is are all of your planes when loaded for flight? If I add pitch trim, how do you all have the control set up in the cockpit for simplicity and where did you find room for it?

Thanks in advance

I think my airspeed is very accurate because when I bought it the static source was the cockpit. I found that the air disturbances around the cockpit gave innacurate airspeed indications due to venturi effect around the cockpit giving an atrificially high pitot to static comparison. .01 PSI is equal to 60 MPH of airspeed indication (thats right .01!) So I added a pitot static mast in the original pitot location so the pitot static comparison is taken at the exact sxame location. There should be no total dynamic pressure variations at different locations since they are one and the same now. It is a bit difficult to fully stall (which adds fuel to the nose heavy scenario) but when I stall its around 35 MPH indicated.

Im really happy with my Avid so far and have been having lots of fun. Looking forward to your inputs.

Mike

Mike,

Take one of those small 6" long bungee cords that they sell in the camping section at Walmart. Tie two knots in the middle with about an inch apart. Put 3 zip ties around your stick about 1" apart with the buckle facing toward the front of your plane. Hook the bungee on the cross member. You can move the bungee up and down the stick on your zip ties for more or less tension. I've been using this technique for 200 hours and it's very effective and incredibly simple. I have my flaperons rigged so that I'm almost hands off at cruise but any reduction in power causes mine to head for the earth too. The bungee works great to make up for this.

[FoxDB 17]

Well I finally got around to installing these things today. I put the tips of them at 4" from the gap between the horizontal and elevator. It's a lot of further forward than any other airplane I've seen. This was per the instructions I received via email from Stolspeed and it's also what he has published on his site so I went with it. Here's a bit of tutorial on the install.

First off because they were made for a wing they have a very slight curve and the instructions call for a slight rub on some sandpaper to flatten them out some to go on the flat surface of the stab. I used 220 and just a couple of passes.

So step one...sand sand sand, then wipe on a rag of denatured alcohol, then set aside.

Luckily the Stolspeed comes with their adhesive laser cut to fit the foot of the VG.

You have to peel the first layer off the 3M adhesive with the tip of an exacto. They come right off.

Next stick the VG to the adhesive. All of this is somewhat time consuming but not too bad. I did all of this at home in about an hour.

I used a pencil to mark out 5 or 6 marks at the 4" point. Rather than draw on my fabric I used some painters paint to make my line.

The stolspeed VG's come with two templates in the kit. The one for the stab is 30mm spacing. Once you get going with the template the actual install goes pretty quickly. I put 36 on each side. The adhesive they use is a 3M product and works well. It's fairly easy to peel one off if you don't' like the placement. Here are some pics of the install.

The sanding, cleaning, sticking station...this part is a bid tedious but not too bad.

Some shots of them installed before I pulled my tape line.

And now what you've been waiting for...well do they work??

Conditions: OAT 98 degrees Winds 10 degrees off at 7kts Field Elevation 120ft Density Altitude 3200ft Empty wt 535lbs 9 gallons of fuel on board

On my initial takeoff I did my normal thing and the first thing I noticed was the tail came up extremely quick. Climbout felt normal. I went to 3500ft msl to try and get out of the heat. During the climb the stick was farther forward than it used to be.

Once the OAT got down to 75 or so I started doing various stalls. I started with a power on and right away I noticed that there was a noticeable buffet and break which I never used to have. Not sure of the speed as I was damn near vertical.

After that I went into slow flight I was cruising easily at 45mph IAS flaps UP. Flaps down I was able to stay level at 40ish. Before anything below 45 and I was falling out of the sky.

Next was power off. Flaps up before power off stall was 44ish. After was 40 with a noticeable buffet and break once again more like a Cessna. Flaps down stall was 35-36. Overall I decreased my stall speed by 4-5mph.

After the stalls and falls I opened her up and headed back to the airfield. The stick in cruise is farther forward now than it used to be. I flew my first approach at my normal speed of about 55 on final. Pitch felt way more solid. I did a stop and go. On the go I held the brakes and shoved the stick full forward with the flaps at 15 degrees and I was able to lift the tail and hold it level without moving. I could NEVER do that before. I let off the brakes and the tail dropped some but I was able to pull it off slower for sure. On my second approach I flew it at 50 which before would work but without a lot of power I would touch TW first. 50 felt great so I tried my next one at 45 hanging on the prop which I anticipated a TW first landing and plop onto the mains which happened but it was about the same as flying an approach at 50 before.

I can't wait to get my taller gear on. With that I think I can comfortably fly an approach at 45 to get in super short.

Keep in mind these numbers are just my numbers on my indicator. As a trend I was able to fly approx 5mph slower all the way around which in the world of STOL is pretty huge. I'm happy with the results and it was pretty cheap. I think I'm gonna go ahead and put them on my wings next and try it.

I got my VG's from www.stolspeed.com He's a nice guy, the instructions are clear, and the product is nice. Sheesh I wish I could leave this thing alone.

Hi Joey,

Are you any closer to installing VG's on the wing? I would be very interested in your results.

Dave

[BryceKat 125]

Mike,

my pitch trim is an electric mac servo with a rocker switch mounted just above the throttle which nice b/c i can keep a hand on the throttle and operate the trim with my pointer finger. Bryce

[C5Engineer 1170]

Just noticed this thread is from 2011. Guess I should get around to installing the VGs.... Extending the elevator to MK4 dimensions and adding electric pitch trim was probably the single best mod I've done since this era of the evolution of #279. 

[EDMO 1078]

Just noticed this thread is from 2011. Guess I should get around to installing the VGs.... Extending the elevator to MK4 dimensions and adding electric pitch trim was probably the single best mod I've done since this era of the evolution of #279. 

It's been so long, I have forgotten whether you are going to put them on top for slow flight or bottom of the wing for faster cruise ?

Well, when you finish tanning in the sand, maybe we will find out.

EdMO

Edited 20 Oct 2015 by EDMO

[chopndrag 226]

Vg's on the bottom of the wing gives faster cruise?  Please do tell I never used vg's on my planes but going faster will make me interested

Just noticed this thread is from 2011. Guess I should get around to installing the VGs.... Extending the elevator to MK4 dimensions and adding electric pitch trim was probably the single best mod I've done since this era of the evolution of #279. 

It's been so long, I have forgotten whether you are going to put them on top for slow flight or bottom of the wing for faster cruise ?

Well, when you finish tanning in the sand, maybe we will find out.

EdMO

[EDMO 1078]

Vg's on the bottom of the wing gives faster cruise?  Please do tell I never used vg's on my planes but going faster will make me interested

Just noticed this thread is from 2011. Guess I should get around to installing the VGs.... Extending the elevator to MK4 dimensions and adding electric pitch trim was probably the single best mod I've done since this era of the evolution of #279. 

It's been so long, I have forgotten whether you are going to put them on top for slow flight or bottom of the wing for faster cruise ?

Well, when you finish tanning in the sand, maybe we will find out.

EdMO

 

I think Joey followed up and gave us a report on his experience with the VGs in another post - maybe not faster cruise?   EDMO