I keep getting catalogs from a certain farm equipment supplier, and along with all kinds of other stuff they feature these new ceiling fans (for your hen house etc.) that move more air for less power and make less noise. I also get a trade magazine that is for installers and builders of very large grid tied wind farm type wind turbines, and they are also taking note of this new blade technology.

Nowhere is it said that any airplane prop people are paying attention to this! WTF?? I just emailed Warp Drive (figuring the certified prop makers are too bogged down by red tape) and included a link and a request to tell me they are all over this and will soon be offering it as a buyable product. EVERYTHING about it shows great promise for "us", and with the composite prop technology out there now manufacturing it should not be a problem. I clearly stated to the Warp folks that if they need a test bed, I'm there. Less noise, more thrust on less power, sign me up. Am I missing something here or what? I posted about this a year or so ago, and thought I'd do it again, I want one and I want it yesterday. http://www.gizmag.com/bumpy-whale-fins- ... mics/9020/

I'm certain there are all kinds of hot ideas to make our Lyc's and Cont's run on water...they just didn't survive the first encounter with reality, that's all. It happens.

I'm not saying anything about whether it might have merit- it's just that things like this don't lead to a flurry of press in a single month in 2008 and then nothing for almost 4 years without a sad ending, that's all. Some folks are great promoters- it's a talent. But there are a lot of naked emperors out there.

If it works as good as they say, it's a wonder someone doesn't try it. I always wondered why if water will run faster through a corrugated pipe, and gas will flow faster through a corrugated nozzel. why not build a corrugated Fuselage? I'm not talking like a Republic Seabee or a Ford Tri motor but with the ribs running against the wind. A sailboat will be faster if you lightly sand it because the water swirls in the small scratches so the boat actually rides on water and not on the hull. Seems like the same principals would work on air the same as water. Just curious?

There is a huge difference between a drive prop and a driven prop, like in a wind turbine... The driven props are alot more forgiving over the wide spectrum of operation. Back in the days of my hydro racing a good prop builder was worth his weight in gold and that line of work is about as close to the phrase " it is black magic" as it comes. I have seen props that looked identical, measured identical and one was 4 mph faster in the kilo then the other one.. When you are dealing with fractions of a second a 4 mph jump is like tomorrow.. IMHO.


Ben.

I'm sure somebody will eventually post a picture of a plane tied down at birchwood. It has what looks like duct tape and paper mache bumps on the leading edges of its wings. I have heard a few different stories about it but I don't know who to believe.

Arctic -
lol, maybe I will go take a picture of it this week. That thing is a monstrosity. Heidi Reuss and I walked past it about a year ago and she had a great many things to say about people doing things like that to airplanes.

I like the fact the big ceiling fans are in full production, and have been for a while now, by a big "for real" company and being sold all over the world with great results. Keep an eye out in small residential type fans to see if the technology trickles down. I'm sure Warp Drive will get back to me any day and will take me up on my offer to be the test dummy Come to think of it they didn't last year but what the hell, it doesn't hurt to stir things up a bit! Imagine the marketing a prop company could do IF it worked at all.

As far as using a rough surface, it was a key development in the hang gliding world in the late 80's that allowed gliders to increase in speed from around 45-50 mph to 60-70 mph in a dive. This was done by using a criss-crossed kevlar scrim outside the mylar leading edge to roughen it (a lot).

http://i588.photobucket.com/albums/ss32 ... _PX10T.jpg

When a body transitions from laminar flow to turbulent flow, the coefficient of drag drops significantly at the transitional Reynolds number. It then rises again as the Reynolds number increases. It doesn't take long before the drag is once again higher than it would have been had the flow remained laminar. The trick is to roughen the surface to induce turbulent flow at a desired speed to take advantage of this narrow band of reduced drag.

http://www.aerospaceweb.org/question/ae ... g-disk.jpg

Golf balls fly at a speed well below the natural Re number transition zone. The dimples are added to induce transitional flow at a the lower speed of flight.

As for the whale fin technology, there seems to be a shortage of actual data. here is some:

http://www.union.edu/academic_depts/mec ... Poster.pdf

Not so very convincing. I see a ton of claims, like 20% more efficiency, etc., with no data or peer review that I can find, by all the breathlessly optimistic and hungry-for-news green press. But yes, it would be interesting to see some data on the idea.

One of my EAA chapter members is Jack Norris. Jack was the Technical Director on the Voyager project. He wrote a book called "Propellers Explained", which tries to finally de-mystify propeller design for the unwashed masses without engineering degrees. Although the book is written in a rather overbearing manner, Jack has indeed made it easier to understand how props work and don't work. Several of the modern prop makers are listening and adopting what is in his book. Any of you who are more than a little interested in props should own this book.

Essentially, the big point in the book is that since the lift of any wing (incl. a propeller which is a spinning wing) must always go to zero at the tip, you don't want the tip to be working hard because most of that work is wasted. Hence a blade shape that is wide in some areas but tapers to almost nothing at the tip.

Articmayhem, is that thing still there?????!! I saw that years ago...and have some pics...guess I better go scan them. I wondered what in the hall would ever inspire someone to do such a thing...now maybe I know?
John

The fact that someone could just make a bunch of plaster humps and try them on an airplane seems like a reasonable idea... as long as you can take the stuff off and go back to a stock airplane without too much difficulty.

Nature has has a long time to figure out what works. The bumps on that whale fin are not there by chance, I'll guess.

The model airplane people would make a mold for a composite "tubercle" and double-stick tape it to the wing, see if it works, then take it the hell off before our Favorite Aviation Administration showed up. I've ever done anything like that

But remember, a lot of people laughed at VG's and would never believe that some little stick-on piece of sheet metal could make the already-beyond-improvement Super Cub fly slower and turn tighter. Now those same guys are trumpeting how well VG's work on their Cubs.

If you go to the Aircraft Spruce site and search for "Prop Vortelators" you will find kits available for experimental and certified aircraft props. They are basically like little VGs that claim to reduce the drag of the prop in the least efficient areas. I have not purchased one of these kits, but I am dying to know if they really work as advertised. If you try one of these, please let us know the results.
MontanaPacer

MontanaPacer wrote:If you go to the Aircraft Spruce site and search for "Prop Vortelators" you will find kits available for experimental and certified aircraft props. They are basically like little VGs that claim to reduce the drag of the prop in the least efficient areas. I have not purchased one of these kits, but I am dying to know if they really work as advertised. If you try one of these, please let us know the results.
MontanaPacer

Those prop vortelators look very interesting. At least if they don't work you're only out 90 bucks. Might be worth trying?

Weird bumps on propellers reminds me of over 40 years ago, working for the Naval Undersea R&D center. They had a guy that only designed propellers for submarines and torpedoes. He was doing pioneering work in finite element analysis and the resulting designs were absolutely non-intuitive. They had humps and bumps you would never think to try as an experiment. Those whale bumps look a little like them. His propellers were the best in the world at the time.

On the other hand, if bumps are such a good thing, why don't other fish and swimming mammals have them? You would think that more of them would have shown up in evolution if they were really for improved swimming efficiency.

Good luck trying out the prop vortelators. I'll be really curious to see how they work.

tom