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.
Make sure to check out the Testimonials tab to see what others are saying.
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 since the shape of our VGs is optimized for a high drag-to-benefit ratio. We include all the instructions and templates you need to find this spot and since we've sold well over 2000 sets of VGs since 2004 we've got the installation location really dialed in by now.
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 or using VGs with the wrong sail shape. 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.
Others have tried to copy our VGs but didn't know the science behind the shape and got it wrong which adds drag.
Q: What are your VG's made from?
A: Landshorter plastic VG's are precision molded from a very clear, UV stabilized Lexan (same material used in skylights in desert homes) and our metal VGs from a proprietary aluminum alloy that greatly resists corrosion.
The plastic is virtually unbreakable, extremely lightweight (100 weigh less than 1 ounce) and won't yellow in the sun since we chose the right material and proper thickness. Some of our competitors use thin flexible plastic that although cheaper to manufacture will get brittle and crack in the sun over time.
The clear is very attractive though they can be painted to match your plane if your want a more conventional look.
Though you can hit our VGs with a hammer and they won't break, their kryptonite is solvents from harsh chemicals such gasoline. So if you spill gas on the VGs while you're fueling they won't dissolve but will "craze" the plastic which beside ruining the beautiful clear color will weaken the plastic. If you think you might spill gas on your VGs or want to clean around them with a solvent then consider our metal VGs- they are impervious to about anything and we think are worth the little bit of extra cost. Especially when you think about future re-sale of your aircraft.
The bottoms of both our plastic and metal 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 flat aluminum extrusions.
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. The most critical thing about VGs in order of importance are:
Shape (ours are optimized for the ideal drag-to-benefit ratio)
Angle (our templates get you dialed in)
Chordwise distance (our manual gives you what you need to set)
Spanwise distance apart (the more the better but about 60 per wing is a great bang-for-the-buck)
If you <wisely> decide to use them on the underside of your horizontal stabilizer to improve your flare and get the most out of your wing VGs then you will place them about 1" apart and just in front of the elevator.
Q: How many do I need?
A: Our kits comes with 120, 80, or 40 VG's which is enough to do either one complete aircraft wing (60 per side) or one complete tail (spaced around 1" apart). If more VG's are needed (or you lose a few) then you can order the kit of 40.
In general the aspect ratio (span over average chord) for most planes is pretty similar so lower span planes typically have higher wing loadings (weight over area) so need the VGs closer together and longer winged planes can use them further apart. Consequently using a ratio, rather than a fixed distance, is appropriate.
The more VGs you use the better the benefits but it's not linear so if you put twice as many on you won't get twice the results. About 120 per wing seems to be the sweet spot.
Although for special applications use more. For example one aircraft I flew was used primarily for predator control and spent its time literally at treetop level. There were about 300 Landshorter VGs on that wing and the responsiveness and stability were absolutely amazing for that type of flying.
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 or use our metal VGs.
Q: Your prices are so low you probably get your VG's made in China, right?
A: No way, Landshorter plastic vortex generators are 100% "Made in the USA" right here in North Idaho 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: The shape of our VGs is designed from wind tunnel testing to minimize drag and provide the cleanest vortex with the best benefit. Other companies get the shape wrong and while nearly any shape will spin the air, details matter to do this with minimal drag.
Also, make sure to ask any vendor if their VG's come with a 100% GUARANTEE.
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 other companies out there.