VG installation with STOL kit

[MontanaBird]

I have a (fantastic) '56 170B which I would easily lay down in front of a bus for. It has an existing STOL kit (Sportsman's I believe...) which clearly enhances its performance/handling. It also seems to make it even more the handful during our strong, gusty spring winds.

Does anybody have any experience with also adding VG's onto the already modified leading edge? Is this STC'd? And if so, what changes were noted?

I fly regularly into most of our nearby short rough muddy and very fun strips in Idaho/Montana, and we often discuss what other things we can do to accomodate this kind of use.

Thanks for the help!

MontanaBird
Missoula, Montana

[Bruce Fenstermacher]

First the legalities. Though I'll bet it doesn't have a statement prohibiting it directly I'm sure the STC is approved on unmodified wings. Most STCs have a blanket statement that says basically as part of the intallation an installer would have to insure that no other modifications interfered with the performance that was proven for the VG STC approval. While I doubt VGs would effect the aircraft negitively in light of what you want to accomplish, you may be held to the task of proving it by the FAA.

Now from the perspective of a person with a few hundred hours flying with just VGs I think that it wouldn't hurt and might add additional control authority while your already at the slow speed the cuffs already afford you. You might find yourself so comfortable you will fly even slower in that envelope. I also think that the VGs that are placed under the elevator as part of the STC will help with elevator authority at slow speed.

I also think you have to consider to much of a good thing. If your approach is so slow and nose high that you can't see over the nose and then land tail wheel first slamming the mains to the ground, how long will the airframe last.

This question would be a good one for Micro Aerodynamics the STC holder to see what they say

[GAHorn]

I'm sure any seller of VG's will have nothing but praise for their products.

My mantra about VGs has not changed: They're useless on an airplane that will already land in places it can never get out of,... and, besides never getting your money back out of the investment when it comes time to sell it,... they complicate airworthiness and maintenance issues.

[buzzlatka]

George,

If VG's could shorten your takeoff roll you could takeoff out of more places. Wouldn't that count for something?

[GAHorn]

George,

If VG's could shorten your takeoff roll you could takeoff out of more places. Wouldn't that count for something?

See if you can get the VG-sellers to guarantee shorter takeoff distances in writing. (and it won't change the fact the airplane without VGs....will still land shorter than it can take off WITH them. In my opinion a better return-on-investment would be to increase horsepower.)

[jrenwick]

There are differing opinions on this, and each is entitled to his own, IMHO. I have a STOL kit on my 170. I wouldn't install one if I didn't already have it, but at the same time I'm not at all sorry to have it. I can outclimb a stock 170, and being slower on landing is not a bad thing. It does require a different technique for landing, however. It took me an awfully long time to figure out that the airplane really needs 40 degrees of flaps out to land gracefully.

[n2582d]

There are differing opinions on this, and each is entitled to his own, IMHO. I have a STOL kit on my 170. I wouldn't install one if I didn't already have it, but at the same time I'm not at all sorry to have it. I can outclimb a stock 170, and being slower on landing is not a bad thing. It does require a different technique for landing, however. It took me an awfully long time to figure out that the airplane really needs 40 degrees of flaps out to land gracefully.

John,
It's interesting to hear that you wouldn't install a STOL kit if you didn't already have one. I'm on the edge of purchasing a Sportsman STOL but would be glad to be convinced not to. My reasoning for buying one is not so much for the STOL takeoff and landing benefit, although that looks impressive if one is to (naively?) believe Sportsman's figures. I would buy a STOL kit to reduce landing speed in the event of an engine failure away from an airport. I understand that kinetic energy is a function of the square of the velocity. So using Sportsman's Vx numbers for "impact speed" one has cut the kinetic energy nearly in half. I'm no authority on this--input by those that figure this sort of stuff out for a living would be appreciated. I see by the pictures of George's recent guest that JlWild has a Sportsman STOL. What does Jim and/or MontanaBird think of your STOL kits? Would you (and others that have them) install them now if you didn't already have them? How would you compare your numbers to those given by Sportsman/Stene Aviation?

Sorry to hijack this thread. There is a lot of debate on the CPA forums as to the efficacy of VGs together with a STOL kit. My feeling is that after I had spent $1500 on VGs there is a strong placebo effect. I would be inclined to believe they make a significant difference even if it couldn't be quantified.

[jlwild]

Gary,

I am with John on STOL kits. My '55 B model N3415D (my second 170) came with a Bush STOL conversion when I purchased it. My first plane N2981D (a '55 B model) I owned while living in Alaska did not have one. If I live long enough to buy a 3rd 170B I would look for one without the STOL kit. Reason......1) as George says you get into short places you can not get out of, 2) it adds weight (loss of useful load) and 3) the plane flys well enough IMHO with out a STOL kit.

[Jimmy M.]

The stol kit will let you slow down and land short.....but there's no substitute for horsepower when trying to get out short.
You can have all the stol kits you want but they aren't gonna help you on a high D A
day coming out of a short strip or a small lake.
I have the Sportsman kit and I wouldn't be without it, BUT ....I also have the big engine

As far as adding VG's when you already have a cuff..............i think you'd have to check with both stc holders for their opinions.......

good luck with it........

[jrenwick]

John,
It's interesting to hear that you wouldn't install a STOL kit if you didn't already have one. I'm on the edge of purchasing a Sportsman STOL but would be glad to be convinced not to....

I'm not sure I could (or should) convince anyone one way or another. I believe the (Horton STOLcraft) kit was installed on my airplane because it was located in Alaska, where something like that has some obvious utility. I don't need it for what I do, but as I said, I do enjoy what it does for the airplane.

It's been said here more times than I can count that it can get you into shorter strips than you can get out of. But I think it's also true that it lets you get out of shorter strips than you could with a stock 170 -- especially if obstacle clearance is a factor, because it will let you climb quite a bit more steeply than a stock 170 can.

The big drawbacks are the added weight of the cuff, fences, gap seals and wing tips, and that it makes the airplane trickier to land as compared to a stock 170. The problem is that if you land with, say, 20 degrees of flaps -- no problem in a stock 170 -- you may find yourself up in the air again if a puff of wind comes along. The solution to that, as I said, is to land with full flaps (just as the owner's manual recommends ). You can easily fly over the fence at 50MPH indicated that way, and at that speed a nice landing is a piece of cake.

Whether it's worth installing a STOL kit all depends on what you expect to do with your airplane. If you do a lot of off-airport stuff, I'd bet you're going to be glad you did it.

[canav8]

There are differing opinions on this, and each is entitled to his own, IMHO. I have a STOL kit on my 170. I wouldn't install one if I didn't already have it, but at the same time I'm not at all sorry to have it. I can outclimb a stock 170, and being slower on landing is not a bad thing. It does require a different technique for landing, however. It took me an awfully long time to figure out that the airplane really needs 40 degrees of flaps out to land gracefully.

John,
It's interesting to hear that you wouldn't install a STOL kit if you didn't already have one. I'm on the edge of purchasing a Sportsman STOL but would be glad to be convinced not to. My reasoning for buying one is not so much for the STOL takeoff and landing benefit, although that looks impressive if one is to (naively?) believe Sportsman's figures. I would buy a STOL kit to reduce landing speed in the event of an engine failure away from an airport. I understand that kinetic energy is a function of the square of the velocity. So using Sportsman's Vx numbers for "impact speed" one has cut the kinetic energy nearly in half. I'm no authority on this--input by those that figure this sort of stuff out for a living would be appreciated. I see by the pictures of George's recent guest that JlWild has a Sportsman STOL. What does Jim and/or MontanaBird think of your STOL kits? Would you (and others that have them) install them now if you didn't already have them? How would you compare your numbers to those given by Sportsman/Stene Aviation?

Sorry to hijack this thread. There is a lot of debate on the CPA forums as to the efficacy of VGs together with a STOL kit. My feeling is that after I had spent $1500 on VGs there is a strong placebo effect. I would be inclined to believe they make a significant difference even if it couldn't be quantified.

Gary it is interesting your reasons but be honest with yourself. If the only reason to consider VG's is because off field landing, you definitely got bigger problems on your hands with engine out scenario. I could never recommend to anyone that suggestion as a reason to get VG's. The most important factor and the only reason why you would install VG's is for greater Stall Margin. No other reason. It is absolutely insane to think VG's will get you a couple hundred extra feet in an engine out scenario. Don't waist your money, seriously. Now if you would like to reduce your wear and tear on the glorious 170 for owner maintenance costs during landing, I cannot give anything other then blessings for your motive. Over the longterm your costs will be lower due to wear and tear from lower speeds.

[n2582d]

Gary it is interesting your reasons but be honest with yourself. If the only reason to consider VG's is because off field landing, you definitely got bigger problems on your hands with engine out scenario. I could never recommend to anyone that suggestion as a reason to get VG's. The most important factor and the only reason why you would install VG's is for greater Stall Margin. No other reason. It is absolutely insane to think VG's will get you a couple hundred extra feet in an engine out scenario. Don't waist your money, seriously. Now if you would like to reduce your wear and tear on the glorious 170 for owner maintenance costs during landing, I cannot give anything other then blessings for your motive. Over the longterm your costs will be lower due to wear and tear from lower speeds.

I'm not considering installing VG's at this time. I'm considering the Sportsman STOL. I installed a Bush STOL kit on an L-19 I flew years ago. I was quite impressed with the performance. It worked so great in fact, that the plane was able to fly backwards! That may have had something to do with the winds through Banning Pass though. If Sportsman's numbers are to be believed, it looks like the plane can almost get out of any field it can get into. 760' over a 50' obstacle landing and 780' over a 50' obstacle taking off. Again, how do those numbers compare with what those of you with the Sportsman STOL see in the real world?

[canav8]

Gary, I will be the first to admit that paper is fabrication of the truth. I would never plan a takeoff or landing based on a published number without somesort of padding. My personal limitation is 25%. I would never try to put a 170 in or out of somewhere because a piece of paper says I can. Generally what paper doesnt tell you is that the engine is a fresh engine and a standard atmospheric day. I have read to many times where the pilot is in the hospital and quoted as saying well the numbers said I could. There is no reason to push that close. Sorry, I knew that you knew that, just a rant. Trying to protect people from the NTSB accident blog. Doug

[Bruce Fenstermacher]

One of my biggest regrets of totaling my airplane is that George will never get to fly it with the VGs. But Jim Wildharber did get my standard demonstration of full aileron authority at ridiculously slow speeds at Duluth. Jim actually flew the demonstration while I told him what to do. His reaction was that he did not believe he could fly his leading edge cuff equipped airplane as slow with the same authority. But to be fair perhaps he never tried to do so.

Jim how about giving us your thoughts on your experience, short as it was, with VGs and their effectiveness.

And yes I'd rather have a more power which is the biggest help with short departures but I can't afford that. But I can afford VGs though I didn't pay for my first set. If I was going to routinely operate in and out of a short strip like a 1500ft strip or shorter, I wouldn't hesitate to install VGs on any 170 (or Cub) I owned. No they won't help you shorten your takeoff roll, but once in the air if your at a steep angle of attack trying to clear that obstacle it is much more comfortable with the control VGs afford than without. And for the half of the operation called landing that can be done slower and safer.

BTW the discussion is not whether someone should install VGs or a leading edge cuff, but what effect positive or negative the addition of VGs would be to an airplane with a leading edge cuff.

[canav8]

Gosh Bruce, Sorry, I didnt see that. He was asking about VG's I thought. No doubt the Sportsman STOL will help. I also thought they included VG's from what I have seen on the install at least from the Sportsman video. Doug