Warbird Information Exchange

I don't know if it is Aeroproducts or not, but Tony Banta's Kimberly Kaye has a non-cuffed prop with matching numbers. He said it was expensive and hard to find a NOS prop like that. I'll look through my pictures and see if I have a closeup.

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Neal,
The H prop is a nice working and running prop for a stock application, they will jold up fairly well up to around 100". The H regulator can't take high HP engines as they will fail a seal and force hydraulic fluid into the spider. If you pull one of the blade shank grease fittings out, as Kerch did for me at Reno 2005, it goes SSPSPSPPTTTTPTP and squirts hydraulic fluid about 4 feet through the air! Kerch told me that "I've lost so many races from that sound it makes me sick!" That would be Crocker's airplane. They make that work buy using a Skyraider regulator/spider and install T-28A blades. Yes the Skyraider is 6o spline, an adapter sleeve is made to fit it on a Mustang 50 spline shaft. The Raiders regulator is of a greater capacity than the H and will hold up to the load. My H prop is on Dan's machine, Leeward has an H prop but changed it last year to a cuff for Ricky's race motor at Reno. That other Mustang in Texas as shown has one. As far as a true "K" Aeroprop goes, I've never seen one. I do know that it is differant than the H. My understanding was that the "K" Aeroprop was very unreliable and production was fairly short. That is one of the differances between a K and a D Mustang. The K model, as Jimmy's Frenesi is, had an Aerproducts prop and the air inlet covers for the filter boxes on the chin cowl are of a slightly differant shape, other than that the 2 airplanes are the same. The way they were turing up the RPM, Hovey & Z, was to use an H regulator and spider with the T-28A blades which are shorter. I think the prop dia with those blades is 10FT. With .420 gears and a 10ft prop you can run in that RPM range without the prop tips going supersonic.

That help Neal?
Sparrow

Mike -- That helps an enormous amount. It was actually an interview Scotty G did with Kerch about his experience with Crocker's racer that got me thinking about these -H prop issues again. He described (in much less detail) the issues you are talking about with the seals.

So for racing applications what was the advantage of the -H prop over the less mechanically troublesome Ham Standard variations? Lighter, since it was hollow? More area -- it looks more wide chord...

So the T-28 blades are also Aeroproducts? I thought, though, that Stiletto was the first Mustang to use the T-28 blades, and that was not til the mid 1980s. Was there someone earlier? I know Voodoo has used them more recently -- were there others?

Which brings me to my next set of questions -- actually more germane to our book project. It seems there was another type of blade used extensively on the hot Mustang racers from the mid 70s into the late 80s -- the "modified" Hamilton Standard blades from the Canadian Merlin-powered North Star transport. My understanding is that is that they fitted into a standard Mustang Ham Standard hub, and were first used by Zeuschel on Miss Candace/Jeannie. The same or similar blades were then used extensively on a whole series of Mike Nixon- engined racers, including at least Mangia Pane, Dago Red and Strega (til Tiger switched props so dramatically in 1987). I have an article where Z refers to these as his "special Hamilton Standard racing prop" and says they added at least 10 mph over the cuffed Ham Standard they had to use after he bellied Jeannie in in 1980 and destroyed the racing prop they had had on it til then. Some of the John Tegler articles about the conception and development of Dago Red talk about how much the Dago designers liked the engine-prop combination on Mangia Pane, which I believe was these transport blades.

Are my understandings about these blades correct so far?

I'm assuming these were solid blades, rather than hollow like the Aeroproducts? Who first brought them down to the U. S. and how were they modified? After modification were they shorter than the various stock Mustang props? What was their advantage? Lighter, thinner, different profile? I assume that they worked best with the high RPM -7 blower motors, and less well with the higher-boost at lower RPM Mouse motors since everybody went to the cuffed blades when they got Dwight Thorn Mouse motors? Please let me know if there's anything here I'm off base on!

Mike and Jim -- thanks for your patience with all my questions. For years I never thought much about propellers -- they were just something attached to the front end of interesting and photogenic airplanes. Then when I started asking around a bit the whole thing suddenly started getting dauntingly complex but interesting in its own right, with different people often giving different and conflicting information and opinions. I really don't want to get into writing only to look like an idiot by saying something that only shows my ignorance, and there's really not much information easily available about a lot of these more technical issues. So thanks again for your patience and your help so far.

And, by the way -- anybody out there in WIX land who knows anything at all about this stuff (or has pertinent questions) please chime in -- I want anything I can get about any of this stuff...

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Neal Nurmi

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Many of the original cuff blades have had corrosion issues under the rubberized cuff as well......

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Tom N

That's one of the reasons that the Cavalier Mustangs all had non-cuffed props when they rolled out of rebuild.

I had never heard that, but it makes sense. Can the cuffs be removed to check the condition and then replaced?

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Neal Nurmi

---Wingman Photo---

There is an AD requiring a 5 year inspection cycle about the possibility of corrosion under the cuffs (near some teflon piece if I'm right and Sparrow can help with this) -- that's why you see some with the cuffs removed, others with C-130 style fiberglass cuffs, and then others with real-looking cuffs installed after the inspection.

The AD that Jim refers to is for inspection of the blades under the teflon strip on the shanks of the blades where the blade shank seal lives, and the shanks themselves for corrosion. The prop gets torn apart and the teflon strips removed for that inspection. Usually, unless there is an obvious problem relating to them, the cuffs aren't removed. There is currently a Co. in Texas that installs new OEM type cuffs on Ham Std. props. The C-130 style of cuff has been installed but they are slightly differant and to my knowledge have been somewhat troublesome in service.

Modified Ham Std. props, cuff blade seem to be the best for racing. There are mods you can do to the blades that WILL increase speed fairly dramatically. Remember that a prop is a rotating airfoil. Northstar blades, or Transport as Neal referred to aren't a fast blade, been my experience they are markedly slower. There are some blades out there that have the same profile and twist as a cuff type blade, and a cuff profile blade can be cut out of them. The Northstar blades were desinged for Airliner service in which they needed the lower end power for take off and cruise. They weren't designed for high speed. The blades are kind of rabbit ear shaped.

Just the T28A blades are Aeroprop, they are shorter. If you have a shorter blade, the prop will try to increase speed under the same load. Therefore the prop gov. will sense that and increase blade angle, therefore increasing prop effieciency. The high RPM low boost theory in my mind and experience is not as fast as the lower RPM high boost approach. AT high RPM lower boost, the blades are flatter to allow the selected higher RPM and not taking a big "bite" of air. In the low RPM high boost, the blade angle increases as the RPM stays constant and the boost increases. As the boost increases the angle of the blade increases to hold the selected RPM.


As far as the lighter Aeroprop, that is a nice feature. It is lighter but surprisingly not as much as you'd think. It is nice in the fact that it is less weight for centrifugal force to try and rip it off the front of the engine. Aeroproducts stuff is becoming difficult to find and there are not many folks around who know to much about them or how to rebuild them.

As far as -7 Vs. -9 blower gears, the main issue there is the parasitic HP loss caused by the driving of the supercharger. It really depends upon what you are trying to accomplish with the airplane/engine pairing for racing purposes. They are 2 completely different animals. About the time the -7 gears are all done, the -9 gears are really starting to come alive. The stresses and fatigue factors induced to the engine by 9 gears are, to say the least, very, very high. Having said that, anyone familiar with the gorilla engines has seen all of the steel and aluminum bracing plates all over them.

That help Neal or is it clear as mud!?!?!?

Randy-- where did you get the info about the paddle prop on the Cavaliers? The paddle prop was just the next in production from the cuff prop. The cuffs where mainly installed to provide a higher ram air effect into the air inlet (smile) for the engine. They did however have a secondary effect of torsonial problems as Jimmy mentioned. I would believe that the paddles where on the Cavaliers more as they were the later props that the airplanes came out of production with. Towards the end of the war, the paddle was the prop that was in production.

Sparrow

http://www.mustangsmustangs.com/p-51/su ... 2116.shtml

http://members.lycos.nl/carloslievens/I ... 1/p51k.jpg

K model blades are much more narrow than the H model blades.

How important is blade chord and/or blade area?

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Neal Nurmi

---Wingman Photo---

Mike -- You said

"Modified Ham Std. props, cuff blade seem to be the best for racing" and "Northstar blades, or Transport as Neal referred to aren't a fast blade, been my experience they are markedly slower"

So why would Z claim an added 10 mph for what I think must have been the North Star blades, and why did the fastest racers of the 1979 to 1986 period (except Stiletto with the T-28A blades and occasionally Crocker and Whittington with their -H props) all seem to use the North Star blades? And, why were you and Dan using the -H Aeroproducts in 2005?

You almost sound like you're saying that choice of blades has been as much fashion for each era as actual performance? Which I guess would not surprise me too much, having known some of the owners etc. over the years, LOL.

So are these indeed the Northstar blades? I notice that each set seems to have slightly different tip profile...

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Neal Nurmi

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Both of those props are Paddle props. Dan and I used the H prop 'cause he wanted too!!! As you know from the pics you posted from the late 70's early 80's, RR3 ran the H prop. I'm not going to be specific here, but the blades are modified for a speed increase. And, pretty much as you said, prop choice has been pretty much driven by style?? Prop design and engineering is a very expensive area to get into. It is trial and error to find the right combination, trial and error means $$$$$. Many different things have been tried. A prop that will make the airplane go like hell straight and level may fall on it's face in the turns, already been proven. It all boils down to how much money you want to spend to make the airplane go really fast. Most everyone concentrates on the engine and supporting systems in the airframe, as well as the airframe itself. Propellors, unfortunately are farther down on the food chain. If you want to see Northstar blades, the airplane that came from Canada that Ken McBride owns has them on it. Once you see them it will be clear the difference. There are photo's of that airplane on MustangsMustangs.com

Sparrow

So I'm wrong again ?!??! Boy that gets tiresome sometimes....

So was anybody actually using the Northstar blades to race with?? I am confused (not a terribly unusual condition for me unfortunately...).

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Neal Nurmi

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Not as far as I know Neal.

Sparrow

Thanks Mike -- I suspect you've helped me to not sound totally ignorant and misinformed (except maybe here on this board at least).

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Neal Nurmi

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