i have a good dago red qustion

[BEARCLAW777]

i have a question about dago red and that is is the prop on her a real p-51 standard or is it from a different plane any body know because i don't and how many wing tip designs do you think it has gone trough since 1982??

[Smee Again]

Re: i have a good dago red qustion

i have a question about dago red and that is is the prop on her a real p-51 standard or is it from a different plane any body know because i don't and how many wing tip designs do you think it has gone trough since 1982??

The prop on Dago is a Hamilton Standard cuffed blade propeller, used on the B, C and early D model Mustangs in WWII. The exact blade numbers escape me at the moment, but aside from having the cuffs re-vulcanized in 2008, the prop is pretty well stock.

As for wing tip configurations, I know of at least two: rounded, similar to Strega's and up-swept, like we ran on RRIII. I also seem to remember the racer was originally equipped with "Hoerner" style tips as well, but I'm not 100% certain. Others will certainly know more. Bruce, you out there?

SA

[BEARCLAW777]

Re: i have a good dago red qustion

thank you guys for replying and track the changes to this historic air plane

[bruce lockwood]

Re: i have a good dago red qustion

There have been 3 different propellers types run/tried on Dago up until the time that Dan started to run it. Smee can clarify what he ran.

Here is a breakdown on the blades, from 1982 until 2000. I was directly involved from 1985-2000

1. Original propeller from 1982 to 1995 had Modified DC4M blades (6845). One set was thinned at the tip and re profiled to resemble the original blades on the Galloping Ghost. These had supposedly been custom built by Ham Std. I never cared for the way this propeller made the airplane handle. Too much dynamic mass and gyroscopic effect during turns.

2. Stock P51 paddle (6547A blades) was tried with good test results during 1995 but never raced.

3. P51 Cuff propeller and it was the best (6523A blades). Specifically built for racing and had a number of interesting mods done that have since been changed.

A. I had the blades anodized black on the back side instead of being painted, The paint always gets chipped during ground run up/Take off
The little chips break up the airflow/laminar flow on the outer 2 feet of the prop and reduce efficiency.

B. The cuffs were not stock when the propeller was built up in 1995, they had a different twist and airfoil shape and a carbon layup. The idea was to transition airflow into the intake throat as cleanly as possible. This is critical, as the supercharger is in essence an air-pump with the ability to increase pressure apx 5 times. To keep this simple, for example, if you lose 1 inch of manifold ram (the pressure in the intake trunk upstream of the carburetor) it will equate to a 5" reduction of manifold pressure at the engine and lost HP.

C. Airfoil shape was slightly changed.


As a note (for you aerodynamic numbers crunchers) the best blade consists of a NACA10-(5)(08)-03 which has an aerodynamically efficient airfoil shank section (No Cuffs) This blade was full scale wind tunnel tested to 500MPH/2000 HP. Jets were "the thing" so testing was stopped.

With regards to the wing tips, we had five different set that were tested. All the testing was down on Miss A with a racing Vintage V12's -9Merlin and all the race goodies, VP fuel, ADI etc etc.. I made test runs back and forth between Rosamond airport and Cal City at 5000 ft running 3400 RPM and 100" inches. Chris Wood, Mark Calderwood and I spent a whole week testing propellers, exhaust stacks and wing tips etc.

The following is a summary of what was tested. The original Horner tips (hand formed out of Al and built by "Soop"). A round set much like the ones on Stiletto, a big flared set that was purchased from the Risky Business camp, a set of end plates, and the set you currently see on the airplane. These were designed and built by Robbie Grove.... then copied by everyone. Robbie did all the composites work on Dago and there is lots if you know what to look for. How about a different airfoil shape in the vertical fillet????? no one ever sees that. Or the prop cuffs and composite induction trunk, which was original built of Kevlar and carbon and once other teams saw it they all had to have one/built one.

FYI the 2 styles of swooped tips worked best and netted about 4 kts. I have to go and locate the test date but as I recall I indicated 342kts with them on and 338kts with the other 3. The end plates being the slowest. I liked Grove's the best because the roll rate at speed and during landing approaches was much better than the ones from Risky Business.

Hope this answers the questions. Bruce

[BEARCLAW777]

Re: i have a good dago red qustion

thank you so much bruce and i am working on doing the model right now this clears up a lot of things about this plane

[MRE]

Re: i have a good dago red qustion

Bruce,the carbon cuffs had to be removed in 06 because they started to delaminate. Dan had vibration problems and we found cracks in the black paint on the cuffs,and you could see where the cuffs started to move away from the center of the prop hub. I ''coin'' tested the cuff and we were very lucky we didn't lose one or more. I'am not a big fan of glueing composites to metal,it never seems to last.

[bruce lockwood]

Re: i have a good dago red qustion

MRE thanks for the reply and the added bit of good information. We sent the prop in for IRAN after every race up until 99, not sure what the policy was after that. We generally had really good luck with composite bonds to metal, but I completely understand your reservations.

Its was my understanding that somewhere along the line the propeller was removed using a set of cargo straps and a fork lift. This is OK with a paddle prop (No Cuffs) and marginal with a cuff prop. But the straps put undue load on the carbon cuffs and were the root cause of the initial delamination/glue joint failures... who knows how long that had been going on. There was a special (Ham Std built) lifting sling that picked the propeller at the hub to alleviate this problem, but there was a time or two when it was not available and the prop had to come off.

Dan and I talked a bit with regards to the vibration. I told him that when I flew Dago it was the smoothest race/propeller combo I'd ever flown. So you can well imagine that I followed this with great interest until the propeller finally arrived at the prop shop and into Keith's hands. It took a lot of measuring and templeting by Rudy and Keith before they discovered that the vibration was being generated by a blade issues.
Cheers, Bruce