Frequently Asked Questions
Q: What kind of performance gains can I expect when using Landshorter! vortex generators (VG's) with my aircraft?
A: Most folks are seeing a stall speed reduction of 4 - 12 mph and a reduction in takeoff and landing distance of 10% - 30%. But beyond the "numbers" the biggest difference folks rave about is their improved control when landing. Click here for testimonials.
Q: Are there any other benefits?
A: Yes, definitely. See the "Benefits" section for a list but in a nutshell here's three ways you can use Landshorter! VG's:
1) Add them to your wings to reduce your stall speed, increase your control effectiveness, and make shorter and safer landings. Remember the square rule: if you can reduce your landing speed by 1/2 then you can land in 1/4 the distance.
2) Add them to the underside of your horizontal stabilizer (just in front of the elevator) to improve elevator effectiveness and allow you to increase your angle of attack, fly slower, and keep your elevator authority throughout the flare.
3) Add them to areas where you are getting flow separation (turtledecks, wing roots, etc) and turbulent, draggy airflow. By keeping the flow attached in these areas (controlling the "localized flow") you can reduce your aircraft's drag and increase your cruise speeds(and burn less fuel on your trip).
Q: Are your VG's for use on certified planes?
A: Vortex generators have been shown to work great on certified planes, but despite that they generally improve performance and safety they are not legal to use on U.S. certificated aircraft without an FAA Field Approval (submitted with a Form 337). Contact your mechanic and/or local FSDO for information on this process.
They are legal for use with experimental category and ultralight aircraft and their use is highly encouraged for anyone that values performance and safety.
Q: Will it lower my cruise speed?
A: On most sport type planes you will see NO difference in your cruise speed if you place your VG's on the "sweet spot" of the airfoil. We include all the instructions and templates you need to find this spot and since we've sold nearly 2000 sets of VGs we've got the installation location really dialed in.
Q: It's obvious that all those little "wings" must add some drag, why don't they slow you down?
A: Good question. Without going into too much crazy aerodynamic theory just visualize how the little micro VG spins the air and keeps it "attached" to the airfoil. Along the aft portion of the airfoil the air is turbulent and causes drag to the wing. By keeping the air attached the turbulent flow at the aft portion of the wing is thinned and offsets the drag caused by the VG itself.
Now here's the scoop: any nasty rumors you may have heard about VG's slowing you down a few mph was probably the result of the user placing the VG's too far forward on the airfoil. You will see a lot of installations where the VG's are way up front. In our experience (and a lot of others too) you want to keep them back a little ways (usually around 10% of chord) so you won't reduce your cruise speed.
The design of the VG is also extremely important for reducing drag- our VG's are just the right size and shape to provide optimum performance with the minimal amount of drag. This is based on wind tunnel testing as well as considerable "field experience" from happy users.
Q: What are your VG's made from?
A: Landshorter! VG's are precision molded from a very clear, UV stabilized Lexan (same material used in skylights in desert homes). They are virtually unbreakable, extremely lightweight (100 weigh less than 1 ounce) and won't yellow in the sun. The clear is very attractive though they can be painted to match your plane if your want a more conventional look.
The VGs are very robust and won't distort or break like the guys selling the much more expensive VGs would like you to believe.
The bottoms of our VG's have a slight curve to match the wing's airfoil. This feature allows them to securely adhere better than the standard flat-bottomed VG's made from aluminum extrusions (which are also quite a bit heavier by the way).
Our VG's don't have a really sharp point at the top so are less likely to rip through a wing covering but they also have the proper sail shape to create an efficient vortex with minimal drag.
Q: How do I know where to put them on my wing and tail?
A: Our eight page manual and complete set of computer generated templates give you the information you need to install your Landshorter! vortex generators. Most likely you will end up placing them around the 10% chord line for your wing and spacing them at about 50 per wing (close to 1% of span). If you decide to use them on the underside of your horizontal stabilizer to improve your flare then you will place them about 1" apart and just in front of the elevator. In all cases the VG's are placed at a precise angle to the airstream and are aligned and spaced with the included templates.
Q: How many do I need?
A: Our kit comes with 100 VG's which is enough to do either one complete aircraft wing (50 per side) or one complete tail (spaced around 1" apart). If more VG's are needed (or you lose a few) then they can be purchased individually for $1.50 each.
Just Aircraft's Proven Backcountry Plane- the Highlander
Testing Landshorter! Vortex Generators (they loved them), Arlington 2004
Q: What will I use to glue them on with and will it stick to my plane's covering?
A: The manual suggests a recommended adhesive (a 3M product) plus two alternates which can be purchased at stores such as Home Depot and NAPA. These glues are made for Lexan and will permanently stick your VG's to most smooth surfaces including fabric (Polyfibre, bare or painted Dacron, etc).
Q: Sure, your money back guarantee sounds great, but not if I have to rip the buggers off my wing and ruin my paint job?
A: Valid point... but first off you're going to love the performance gains and won't likely be wanting to remove them. Secondly, some folks will feel more comfortable if they first adhere them with double stick tape (carpet tape you can buy at Home Depot, etc). This will allow re-positioning the VG's for optimum placement. When you get ready to pull them off (to glue them on permanently) then just use a little bit of alcohol or kerosene to dissolve and clean off the tape. All of this is covered in the manual.
Q: Won't that "cheap plastic" not last long?
A: Our plastic is General Electric UV stabilized Lexan, the same material used in skylights in desert homes. It definitely isn't cheap and is very similar to materials already used in many aircraft windshields. If left out in the baking sun for decades you would probably notice some aging (just like paint) and if that's your plan then we suggest you paint your VG's to match your aircraft.
Q: Your prices are so low you probably get your VG's made in China, right?
A: No way, Landshorter! vortex generators are 100% "Made in the USA" by small family owned businesses. Our testing grounds are the hot, high, and short strips of the Idaho backcountry.
Q: What are the differences between the Landshorter! product and those other guys'?
A: Here, tell you what, we'll let you check it out for yourself. These are companies that have good products that have proven themselves in the certified aircraft market. Spend some time checking out how their products work and what their customers think of the performance improvements. Afterwards come back here and see the difference. One hint, it's spell P-R-I-C-E! Also, make sure to ask any vendor if their VG's come with a 100% MONEY-BACK (including shipping) GUARANTEE.
Boundary Layer Research
Pacific Northwest Aero
Q: If VG's are so good then why aren't more people using them?
A: That's the very question that got us started selling VG's. The only reason you don't see 90%+ of the experimental planes out there with VG's has been the high prices and the fact that many pilots just don't realize their benefits. With our aggressive marketing and the fact that we have a great product for less than $100 we think that's about to change.
Q. Are VGs the only products that Harrison Designs, LLC sells?
A. We also offer several fantastic STOL videos and we're never a company to sit still though when it comes to STOL products so keep visiting often for updates.
New! Check out some incredible STOL footage on our Big Rocks Long Props page.
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