• Welcome aboard HomebuiltAirplanes.com, your destination for connecting with a thriving community of more than 10,000 active members, all passionate about home-built aviation. Dive into our comprehensive repository of knowledge, exchange technical insights, arrange get-togethers, and trade aircrafts/parts with like-minded enthusiasts. Unearth a wide-ranging collection of general and kit plane aviation subjects, enriched with engaging imagery, in-depth technical manuals, and rare archives.

    For a nominal fee of $99.99/year or $12.99/month, you can immerse yourself in this dynamic community and unparalleled treasure-trove of aviation knowledge.

    Embark on your journey now!

    Click Here to Become a Premium Member and Experience Homebuilt Airplanes to the Fullest!

Stall reduction with VG's (vortex generators) for LSA's?

Advertise with us
Find deals on amazon
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
I noticed during an initial glance at my S2 plans that the ailerons should be set 1/4 inch down on both sides to help low speed handling/lower the stall speed. The LSA stall speed is 52mph - give or take some instrument errors is this not achievable at take-off weight?
 
LSA stall speed limit is 51 mph / 45 kts max CAS flaps up

Flaps or flaperons won't help at all
VG's, new airfoils, extended wingtips, or lower gross weight will

$97 VG's can lower stall and approach speeds up to 10-15 mph!

070920_52_stall_testVortex_Generator_R3_094.jpg
 
Sound like you know the answer to your own question and maybe advertising products...???

My point being, would a low weight, correctly rigged wing with a correctly formed leading edge Sonerai stall at the LSA limit given the error tolerance of instruments and subsequent inaccuracies in measuring actual stall speed.

You don't reference whether you're talking about a 1 or 2.

John Monnet added wing extensions to the Onex to lower the stall speed to meet LSA regulations.

Go experiment and let us know.
 
One of these days I am going to go stall mine with the camera running to see what it stalls at. I bet its not much over 51mph. I suspect around 55. Sounds like a project for later today ;)
 
:eek: not to be picking on you Jeff but..... that's like the first thing I figure out in an airplane, surely you mean with VG's installed because you already know what the stall is in normal configuration? ::) I would be way more curious to know what the angle of attack is at power-off stall, in my previous plane (wagabond) it was so high that it was basically useless information, if you tried to land that close to stall speed the tail hooking would be extreme.
 
I have only stalled the plane 3 times during the test phase. When I did it, the airspeed dropped to 0 before it stalled. I have not stalled it since I put the tips on.

With no starter, its not something I enjoy doing.
 
mhflyit said:
Sound like you know the answer to your own question and maybe advertising products...???

My point being, would a low weight, correctly rigged wing with a correctly formed leading edge Sonerai stall at the LSA limit given the error tolerance of instruments and subsequent inaccuracies in measuring actual stall speed.

You don't reference whether you're talking about a 1 or 2.

John Monnet added wing extensions to the Onex to lower the stall speed to meet LSA regulations.

Go experiment and let us know.
Click to expand...

I'm looking for a project Sonerai IIL, but I want to know if I can legally fly it first with these mods.
I did my research first, but I was hoping to see if anyone had done this before.
 
Schmleff said:
I have only stalled the plane 3 times during the test phase. When I did it, the airspeed dropped to 0 before it stalled. I have not stalled it since I put the tips on.

With no starter, its not something I enjoy doing.
Click to expand...

How do you calibrate your airspeed indicator for CAS when it's zero?
Is that power on or off?
What speed does it indicate on GPS?
Do you sell Hoerner Tips for the Sonerai?
If so, I want some when I get a IIL project.
BTW - Your video above is fantastic!
 
Power off. it was calibrated by gps.

i looked into selling the tips, but they would be too expensive. I would have to sell the set for $450 and even at that it would take years to recover the cost of the molds.
 
But the Hoerner Tip molds are already made, it's all time, materials, and profit now.
Plus you would be doing a great service to others that want to lower their stall speed.
Did you get some fuel in them too?
Would they be any cheaper without fuel in them?
Maybe Great Planes would sell them for you too?
 
My plane (S-2 midwing) stalls at 55mph power off, if entered slowly, 42mph full power that is from a slow low power entry to full power to maintain alt.
 
Forgot to mention that was 3 days ago at 5000ft DA 95 degrees at the surface, 2000ft elevation. I was at 4500ft MSL and that was indicated airspeed so the true airspeed would be significantly higher than those #s. And that was solo with full fuel so approximatly 830lbs.
 
The Wag also read zero ( to the eye) but after filming it several times you could see it quit before the plummet to zero. I don't blame you for not wanting to do it with a prop only start, it was nerve racking enough with mine the first couple of times until I was convinced it would stay running and stalled straight without a tendency to enter a spin ect.
 
According to the StolSpeed.com website and testimonials, the VG's keep the air flow attached straight over the wing at high angles of attack using tiny vortex tornado's. VG's never allow it to stall and break, just mush with complete aileron control. It's easy to test, it only takes 5 min to add yarn tufts to a wing to check it. Normally in a stall the airflow detaches and flops around wildly. I would also like to see a standard wingtip tuft tested, and then compared to the Hoerner wingtip.

vortex7.gif
 
I note that the claims are for LSA's presumably with a Vne of 135 or less. I would expect these aircraft to have high lift wings suitable for short fields and great climb rates.

Our Sonerai's have Symmetrical wings and some guys are seeing 170 mph. One would not want the aircraft stall speed below the point at which the controls are effective.

I watched the landing video of the Sonerai (on this site). He seems to stall on landing about 62 mph. Mine is about 63.

I enlarged my fin by 40% and rudder by 1/3 but the above still applies.

However if someone has done the VG's with a SII LS I would be interested to read about it.

For the rest of us, I suggest we approach this mod with caution. Bill
 
Bil438 said:
I note that the claims are for LSA's presumably with a Vne of 135 or less. I would expect these aircraft to have high lift wings suitable for short fields and great climb rates.

Our Sonerai's have Symmetrical wings and some guys are seeing 170 mph. One would not want the aircraft stall speed below the point at which the controls are effective.

I watched the landing video of the Sonerai (on this site). He seems to stall on landing about 62 mph. Mine is about 63.

I enlarged my fin by 40% and rudder by 1/3 but the above still applies.

However if someone has done the VG's with a SII LS I would be interested to read about it.

For the rest of us, I suggest we approach this mod with caution. Bill
Click to expand...

Vne is not a consideration at all in Sport Pilot regulations. Vh is the only top speed limit, it is the maximum speed in level flight with maximum continuous power, 138 mph (120 knots) CAS. That is why the Sonex with the Jabiru 3300 can cruise at 170 mph at 8,000' and still be Sport Pilot approved.

According to the Sonex website - "The most common question on these speeds involves the use of the 3300 Jabiru. According to the Jabiru Factory, the maximum continuous power rating of the 3300L Jabiru is at 2850 rpm. At this rpm and under the specified conditions, the Sonex and Waiex cruise at 135 mph."

VG's enhance control, not reduce it. VG's can reduce stall and takeoff / approach speeds safely up to 15 mph!

Sport Pilot Rules
 
S2 P E R F O R M A N C E S
DESIGN LIMIT AT FULL GROSS +/- 4 G's
AEROBATIC LIMIT SOLO W/755 LBS. +/- 6 G's
TAKE OFF DISTANCE 900 FT.
STALL SPEED 45 MPH
LANDING SPEED 58 MPH
MANEUVERING SPEED 115 MPH
CRUISING SPPED AT 75% 140 MPH
VNE 200 MPH
RANGE W/45 MINUTE RESERVE 245 SM
RATE OF CLIMB AT GROSS 500 FPM

bob21635 this is from the GP website - you can limit the max continuous power to achieve a CAS of 138mph. Seems like a stock S2 would meet LSA.

If it hasn't been done yet you may wait a long time for someone to buy, place and test the VG's on an S2 or you could build light with a shorter wing incorporating a Hoerner wing tip and VG's and let us know how slow it will go.
 
You must log in or register to reply here.

Latest posts

Back
Top