Vortelators?

[Bryan Wood]

I stumbled onto this site yesterday and it has peaked my interest. Has anybody tried Vortelators on an RV yet who is on this Forum? Earlier today I called and got some information on the product and the claims are pretty much the same over the phone as on the internet site. Putting some tape onto the airframe and propeller seems like a stretch to gain speeds like they are claiming, but then again they took the time to get STC's to sell these for certified airplanes also. I was told that the RV-6 that they tested on had speeds increase by 6mph from the airframe kit, and another 3mph from doing the prop. There is no data yet on the RV-9A, but it would be great to hear from anybody currently using this product. It takes a pretty serious horsepower gain to pick up speed advantages like this, oh please, please, please be true. If it is by some chance true why don't we try to make this person a very rich man and speed up our planes in the process.

http://www.vortelator.com/

Regards,
Bryan Wood 9A "Flyin the Flag"

[N395V]

Talked to this guy extensively by phone and e mail. Never could get him to show me any data.

An STC means it causes no harm, it is not a gaurantee of performance.

Using logic and common sense. VGs across an entire wingspan get you very little by way of climb or increased gross weight. It takes 50 hp to get an additional 20 KTS, just what can you really expect from 2 inches worth of VGs on a propellor at a location that generates little thrust to begin with.

6 more knots on an RV? I doubt it.

I have a bridge in Brooklyn for sale cheap if you are interested.

[jcoloccia]

This is OLD technology. It also works, although 7 MPH on the top end seems a bit fantastic. Funny, though....I was just wondering the other day why no one's latched onto this in the homebuilder community yet.

Typically, the point of vortex generators in this context are to improve the slow speed characteristics of the aircraft. It's not uncommon to get a significant reduction in stall speed i.e. the wing will stall at a higher angle of attack. Also, control effectiveness at low speeds tends to be better. I'm not sure what effect it would have on spin/spin recovery. That's probably very plane dependent. This all may come with a price, though.....the vortex generators can negatively impact the stall characteristics of the aircraft. You may find that what was once a gentle flop can turn into a rather sharp break with very little buffet. This is not an uncommon side effect.

You may also have a problem if you have a tail dragger in that 3 point attitude with the strips installed may no longer be anywhere near stall....in fact, I believe RV's already have this problem to begin with where 3 point attitude is really a bit faster than you want to be (someone can correct me if I'm wrong here, but this is what I'm told).

I don't doubt performance improvements. Just be aware that it's no silver bullet and it immediately turns you back into a test pilot.

[Dave Cole]

On sailplanes, we call this stuff "turbulator tape", and it is used to initiate an orderly transition from laminar flow to turbulent flow on extended laminar flow airfoils.

Without turbuator tape, modern high performance sailplane airfoils may develop a "seperation bubble" at the point of flow transition. At this point, the laminar flow will actually seperate from the surface (forming a "bubble"), and then reattach itself as turbulent flow where the training edge of the bubble collapses. By placing "turbulator tape" just ahead of this transition point, the laminar flow can be triggered to transition to turbulent flow without the creation of a seperation bubble. The resulting turbulent boundary layer is thinner, thus reducing profile drag.

As applied on sailplanes, turbulators are installed to improve low speed performance. This can be of considerable benefit because of increased climb performance in thermals. However, at higher inter-thermal crusing speeds, the transition from laminar to turbulent flow occurrs without the creation of a significant seperation bubble, and the turbulators are nothing but extra drag.

I don't see how turbulators can improve the maximum speed of an aircraft when the airfoil is operating at low angles of attack where the seperation bubble isn't an issue.

Turbulators may be of benefit, however, when applied to features like struts and landing gear, if there is a seperation problem. Application on propellers is anybody's guess.

Dave Cole
RV-7 wings

[Bryan Wood]

Thanks for the input. Common sense said that this had to be phony or at the very least very optomistic, but just in case somebody had experienced good luck with them I had to ask. Maybe an exercise program and better eating habits might just be the key to making the airplane perform better. Okay, maybe better considered on Friday.

Bryan 9A "Flyin the Flag"

[gmcjetpilot]

Originally Posted by Bryan Wood

I stumbled onto this site yesterday and it has peaked my interest. http://www.vortelator.com/
Regards,
Bryan Wood 9A "Flyin the Flag"

Interesting. They claim 2 to 4 mph for home-builts.

They show a fixed pitch prop application, a short length (6" or less) near the hub. Its on the leading edge, from the spinner towards the tips. They claim up to an extra 50 rpm with a fixed pitch prop (or higher angle of attack for a c/s prop for a given MAP/RPM, giving more speed).


OK, well it looks like vortex generators, well known by Aerodynamist for boundary layer control, So if the magic tape was placed in the proper areas it would be helpful, but where do you apply the tape:

They show Cessna wing Struts, which could help if the flow was separating and causing drag

They show the root area of a prop blade, could be helpful since the prop looses it's airfoil shape for structural reasons

What about RV's? Well besides the root of the prop blade, may be the gear legs, but we use fairly wide cord leg fairings already, but may be a small gain could be found here. It would be easy to apply and see what difference it made.

There is limited use for this on a RV, but would love to try it on the prop. The back canopy of the RV-4/8 gets drag due to turbulent airflow, where air can't stay attached on the back of the canopy. However larger Vortex generators would be needed (clear lexan bonded on).

The root of a c/s prop is a pretty bad aero-shape, but necessary to transition to the hub. Since the airframe blocks this part of the prop anyway it's not a big deal, but reducing turbulent airflow could "IMPROVE COOLING". Since Vans cowl uses Horz rectangle inlets from the edge of spinner to near the outboard edge of the cowl, the prop effects the sir flow in this area. The area next to the spinner SUCKS. May be the vortex tape will help cooling and also DRAG?

VG's in general improve low speed but not high speed, the no free lunch theorem. May be these small ribs will cause less drag? I know a Boeing engineer came up with rib-tape and applied to an America's cup sail boat and reduced hull drag, but the Reynolds number is a bit different for water than air.

George