Vortax Generatos

[astjp2]

Re: Vortax Generatos

Use the Loctite, it will rip off the dope...tim

[cvavon]

Re: Vortax Generatos

The glue from the kit was loctite works very well.

[RobertP]

Re: Vortax Generatos

Cvavon, Thanks will stick with Locktite seeing as it has worked for you. Managed to get half way through painting the little blighters today, etch primer and two coats of spray paint! The hardest part was getting a good paint match.

[water007]

Re: Vortax Generatos

Robert, Have you completed the VG install and flown yet? Curious how the performance changed - if at all. I am on the bubble about whether or not to spend the money.

[RobertP]

Re: Vortax Generatos

Hi, I havnt got as far as fitting them, but I have painted them ready to go and it is the next job on the list after sorting my hole in the exhaust stack!

[senior]

Re: Vortax Generatos

Robert, Have you completed the VG install and flown yet? Curious how the performance changed - if at all. I am on the bubble about whether or not to spend the money.

This is a copy of an E-mail I recieved from Bruce Bixler a couple yrs ago regarding the VG performance on his plain.

"Hi Randy,
I think that VG,s give the biggest bang for the buck, it's like having 10 more
hp. with lots of slow speed stability. Some airplanes don't show a great
difference in short field take offs and landings but we noticed
it on our BC12D, my son and I both weigh over 220 lbs. All 100 + of them have
stayed on. Power on stalls
are almost impossible she just hangs there no tendency to drop a wing.

Love them,
PS the stall speed gets to around 32-35 solo just like a prewar
Cub.
Bruce Bixler"

[fearofpavement]

Re: Vortax Generatos

Yeah, Yellow Duck did get the vortex generators. It has been sitting forlornly in our hangar disassembled for years now. It had been pranged. We did the structural repairs but never finished the fabric work. Not that much to do, just not my forte. (we had to cut away some fabric for welding the strut/gear attach fitting.)
When we acquired this aircraft, we were planning on the other Tcraft leaving and that plan changed so we don't really need another one airworthy. The market stinks and tyranny of the urgent reigns, so it sits...

[water007]

Re: Vortax Generatos

Any updated info on the effects of adding VG's? I finally got mine installed on my BC12-D and So is about 3-4 mph slower, a little better slow flight characteristics, BUT landing"s are a little more difficult (at least until I modify the std 3 pt TC method/airspeeds). After the flare, approaching with the same IAS and even a little slower, on initial touchdown (3pt), it wants to bounce. A veteran TC owner flew it and did the same with him. We are now looking at how to get the beast to STAY on the ground, so any input is appreciated. I guess could always do the wheel landing route!
Frank

[PA1195]

Re: Vortax Generatos

VG's should benefit the Taylorcraft stall behavior, aileron, and elevator control.

This reference (General Aviation Aircraft Design: Applied Methods and Procedures By Snorri Gudmundsson) pp. 269-272 discusses the airflow characteristics of the Taylorcraft's 23012 airfoil. The author notes, describes, and offers an explanation for the airflow separation bubble just aft of the leading edge of the wing. Apparently it contributes to the abrupt lift discontinuity and typical stall behavior. Search Google books to read the pages.

Adding VG's forward of the "bubble" should help reduce that discontinuity and maintain laminar flow over the wing. That's until the flow separation migrating forward from the trailing edge with increasing angle of attack causes an overall loss of lift. Adding them to the bottom of the horizontal stabilizer should help maintain elevator control.

Gary

[water007]

Re: Vortax Generatos

I agree, the engineer in me is a "believer" in the theory of increasing laminar flow should lower stall, better slow flight etc. My problem seems to be it may be too good and getting the plane to settle after TD, i.e., not bounce. It may just take some getting used to slower approach and let it stall completely at TD. I suspect AOA is changing after initial touch causing a ballooning effect.

[astjp2]

Re: Vortax Generatos

Lower your tire pressure to 12psi, less than 10 can shear a valve stem. Also putting on bigger tires will increase your AOA. Tim

[PA1195]

Re: Vortax Generatos

I agree, the engineer in me is a "believer" in the theory of increasing laminar flow should lower stall, better slow flight etc. My problem seems to be it may be too good and getting the plane to settle after TD, i.e., not bounce. It may just take some getting used to slower approach and let it stall completely at TD. I suspect AOA is changing after initial touch causing a ballooning effect.

Yes w/o drag-producing flaps or spoilers they'll float as ground effect alters and reduces the relative AOA just prior to landing adding lift.

Try these steps if your airspeed is capable of detecting 30-50 mph with some visible indication (I prefer one that offers spacing in that range). Note the indicated airspeed and feel (any brief wing drop or mush before leaving ground effect?) when the tail is held on the ground during takeoff. That's an indication of 3-point stall speed under power.

Mark the windshield inside with a piece of tape on the distant horizon when parked. Then go up and fly around at landing power and normal landing rate of descent to get a feel for that visual AOA and the effect of the VG's in a landing attitude.

Stall the plane at landing power and apply x 1.3 Vso to help determine a Vref for a final approach speed in smooth air. Work one for 1.2 Vso and see if it's comfortable. We're talking ~ 48-52 indicated assuming 40 indicated. It may be lower with VG's. I'll know more when my T-Craft with VG's gets here later this week.

Gary

[water007]

Re: Vortax Generatos

I like the idea of larger tires, wanted some anyway, just mo money! And I'll give Gary's protocol for dialing in the speeds a try. Also, I noticed more of a bounce on pavement vs grass (it is in the high 80's here in So. ALA), another variable from the heat near the RW surface. Hank correctly pointed out the air flow over the wing with VG's is technically small turbulent airstreams (i.e., not laminar), but they do "simulate" laminar flow by keeping the air (boundary layer) attached to the wing via small vortices as opposed to detaching at high AOA's. Whewww, this is getting into the weeds where I have not been in decades! I just want a method to NOT simulate dribbling down the RW!
Thanks for the input/suggestions.

[PA1195]

Re: Vortax Generatos

No discussion of performance lift and drag is complete without a reference to Gurney Flaps (Wickerbills): http://www.dept.aoe.vt.edu/~mason/Ma...A2007-4175.pdf

Think of the fun one could have with a fixed or even deployable GF. Maybe make them from a piano hinge and use the center pin attached/welded to one deployable side of the hinge. Run the pins inside and across the fuselage, attach to each other and add simple bell crank to rotate and deploy, and enjoy the added benefits.

Gary

[Dick Smith]

Re: Vortax Generatos

Maybe like this...?