Modifying the spinner; anyone try it?

[kentb]

I have been thinking about adding two spiral vanes to the spinner. The idea would be to compress the air entering the cowl for both the cooling and induction.

Has this been tried before?

Is this crazy?

Kent

[osxuser]

A little.

I don't know if the aerodynamics will work or not, but be sure those things are attached WELL! It would SUCK to fling something like that off your spinner.

[David-aviator]

Originally Posted by kentb

I have been thinking about adding two spiral vanes to the spinner. The idea would be to compress the air entering the cowl for both the cooling and induction.

Has this been tried before?

Is this crazy?

Kent

......an interesting idea, not crazy at all.

The German FW-190 of WWII had a large fan that looked like a turbin wheel aft of the spinner. No doubt it was there to facilitate cooling.

I am of the opinion there is very little air flow past the propeller radius just out side the spinner, reason being the blade has little air foil there, and its rotating profile acts like a barn door. It would seem logical a device to move air should be behind the spinner, not in front of or a part of it.

[seaplaner]

adding two spiral vanes to the spinner. The idea would be to compress the air entering the cowl for both the cooling and induction.

Hmmm, interesting idea. I'm no engineer, so I could be all wrong here; however I'm thinking that the spiral vanes would be pretty draggy, almost like a small thrust reverser.

Also, I might be curious if there would be any induced turbulence. I know that aero engineers worry a lot about air flow, and go to great lengths not to disturb it.

Don't let me be too negative here, it might be a great idea. (In fact, I've already said much more than I know!)

[Kahuna]

Originally Posted by kentb

I have been thinking about adding two spiral vanes to the spinner. The idea would be to compress the air entering the cowl for both the cooling and induction.

Has this been tried before?

Is this crazy?

Kent

Just as a data point for you. Ive been flying for 2 weeks with no spinner. No change in speed or cooling at all.

Best,

[dan]

Originally Posted by Kahuna

Just as a data point for you. Ive been flying for 2 weeks with no spinner. No change in speed or cooling at all.

I'll bite! What's up with your spinner?

[Kahuna]

Well after building the screwless spinner I had a couple flanges break off. As I mentioned on the webpage, it needs a full ring flange in there. Anyway, I took the spinner off to repair.

While in repair, I flew a rocket with an MT 3 blade. That was a mistake. I ordered a new MT prop as a result. again

So I have little reason to fix the spinner whilst I wait for th MT to show up in a couple months. So Heck, I just fly with no spinner. Flies just the same.

Lesson, do not fly a buddies plane with some gee whiz feature you are not prepared to buy.

Best,

[gmcjetpilot]

Keep in mind you have that big fan called the prop right behind the spinner. I am sure the prop will move more air.

Also the problem with doing any thing with "fins" on the spinner is the prop blades as they come out of the spinner are very blunt. The root or shank of a prop near the hub is either round (constant speed props) or almost square (fixed prop). The air flow is majority messed up in this area and there is little you can do but:

Make the spinner huge to cover the blade roots. (P-51D CLICK)


Here is an experimental Mooney that cafe foundation did (kind of ugly). They have a report you can look up. Note inner non-airfoil blade root covered. Also chin scoop should works terrible (poor, bad, not great) on a stock RV cowl/spinner. Van tried it on the firest prototype RV-6, he went back to the RV-3/4 style he has used on all his planes.


Extend to prop way out to make a better transition to the cowl. (Little Reno formula racer CLICK)

Since the Lyc has a crank/prop flange and than a big fly wheel the whole front end is messed up. Going to a large spinner is not practical and would be major modification of cowl. The extension is OK but requires you use a wood fixed pitch prop and more cowl mods.

Aircraft design is a series of compromises all integrated. If it was easy anyone could do it.
When a design hits on the right combo, we pilots should applaud the designers: Van-RV's, Boeing, Kelly Johnson (P-38, U2, SR71), Jack Northrop (Northrop flying wings N-1M, N-9M, YB-35, YB-49 inspiration of the B2 stealth bomber w/ exact same wing span). Last the greatest home-builders of all time, Wilbur & Orville Wright. Hats off to all the great designs and designers; it ain't easy. For every great plane there are 100's of not so great designs.

Keep up the designing and learning.

[RV8RIVETER]

Originally Posted by Kahuna

Just as a data point for you. Ive been flying for 2 weeks with no spinner. No change in speed or cooling at all.

Best,

Another data point. I just finished watching Mike Arnold's "Why it goes so fast" video on his AR-5. Very interesting by the way. Anyway, he fabricated a big spinner at first, then after having problems keeping it attached, removed it al together. He had no speed change at all. The eng who did the drag calculations said it was the build up of air in front of the cowl, which in effect creates its own "cone". His cowl is round, but I would think the effect happens on all cowls, but the front end shape no doubt influences the shape of the air build-up.