[rous]

Hi,
I posted just below, however, I don't think I was very clear. I'm having a lot of trouble finding the correct airfoil for the propellers on my P-3C I'm building. I obtained the correct wing airfoils, but the props are throwing me for a loop. If I am unable to find them, what would be the best way to model them? They are specialized and fairly important in getting a "real" feeling when flying it.

Oh, I'm having the same sort of trouble with the horiz/vert stabilizers. I'm unsure if the wing airfoils are used, or not...

Thank you very much for your help. I'm building this as a birthday gift for my father, who flew P-3's for 15 years while in the Navy...I would like this to be as realistic as possible.

Obviously, once it's done, I'll release it to everyone

Thanks again,
rous

[bogey]

Let us know what the prop airfoils are called, and we'll see what we can do.

But generally, prop airfoils don't matter that much.
It's the final performance of the engine-prop combo that determines how realistic it is, and 100% realism can be achieved just as well with wrong airfoils as with correct ones.

[rous]

Hi and thanks for the quick reply. The propellers are Hamilton Standard #54H60-77. What you said about how propellers don't essentially contribute to the realism surprised me. I would've thought, for instance, that there would be a big difference between a large, wide square tipped prop (such as the 54H60) vs. a thinner, more rounded one...

What about the other airfoils I mentioned...?


Thanks very much,
rous

[coanda]

in real life there is that difference, in x-plane there isnt really.

you can make your props appear to have nice rounded wing tips on hte bitmap, but you will need a prop that will obviously fit that shape into its area.

this means that your prop may overperform.....this is where testing and tweaking comes into play!

the prop section name is handy...the problem is is that no prop manufacturers give away the airfoil characteristics I cant make any sense of the naming system so i think it just must be a serial number related to the airfoil section or the props themselves.

I would expect that the section is of very thin slightly cambered shape, so any low thickness ratio sligtly cambered shape NACA section would probably do just as well.

to be honest, a clark-y section would probably do the job for testing, you can always modify the section curves a bit later.....

as for your vstab/hstab foils, vstab will be a symmetrical section of some type, and again a NACA type foil of the same thickness ratio will do the trick. the hstab can also be symmetrical unless you have evidence to prove otherwise as I know some aircraft do have cambered section stabilisers....that should do the trick...knowing this will help you with the cg location....as a normal location wont require very much trim through the speed range, to keep stabilised.

regards

coanda

[rous]

Thanks! Just for future Reference:

128.25 EXPLAIN THE MODEL DESIGNATION BREAKDOWN FOR A PROPELLER (I.E., 54H60-77). (REF. D)

THE MODEL DESIGNATION FOR THE PROPELLER ASSEMBLY, INDICATED BY INK STAMP OR VIBRATION PEEN MARKING ON THE BARREL, EXPLAINS THE TYPE OF PROPELLER. THE NUMBER AND LETTER GROUP DESCRIBES THE BASIC MODEL, AND THE NUMBER GROUP THAT FOLLOWS THE DASH INDICATES THE MINOR MODIFICATION INCORPORATED IN THE PARTICULAR MODEL. A BREAKDOWN OF THE 54H60-77 PROPELLER IS AS FOLLOWS:

5 - INDICATES THE NUMBER OF MAJOR CHANGES INCORPORATED IN THE PROPELLER.

4 - INDICATES THE NUMBER OF BLADES.

H - DESCRIBES THE BLADE SHANK SIZE. (THE USE OF A LETTER HERE ALSO INDICATES THAT THE BLADES ARE MADE OF ALUMINUM. A NUMBER HERE WOULD INDICATE THAT THE SHANK SIZE AND ALSO THAT THE BLADES WERE MADE OF STEEL, AS IN MODEL 24260).

60 - INDICATES SPLINE SIZE OF THE PROPELLER SHAFT.

-77 - INDICATES THE NUMBER OF MINOR MODIFICATIONS INCORPORATED IN THE PROPELLER.

P.S-Caps not mine

This post has been edited by rous: 20 February 2005 - 06:41 PM

[brett s]

None of that stuff matters in the sim, other than the number of blades of course

The things you need are very hard to get in some cases, impossible in others:

1. Chord width - not usually listed, but you can measure the real thing if you've got access to one.
2. Amount of blade twist - not published, same as above.
3. Airfoil - proprietary information & not published, you'll have to guess...

[bogey]

Regarding brett's point #3...

You CAN, if you're good, make clay molds of the airfoil shape if you have access to the real thing, and a trusting owner.
If you have the shape, you can make a drawing of it and search through various airfoil databases until you visually find a good match.

You're unlikely to find the actual airfoil, but if you find one that's slightly off, you can still use that in X-Plane, as the accuracy even with perfect polars wouldn't be 100%.

With wings, this method can yield good enough shape data to run through an airfoil analysis program and get very good performance numbers.

Edit:
Just noticed that the aircraft in question is a P-3...
Makes it a bit tricky to find that using the hands-on method then, but perhaps Lockheed has some old info that they'll give out. I can't imagine a 50-year-old prop foil is highly classified...

[rous]

" I can't imagine a 50-year-old prop foil is highly classified..."

Indeed not!

In fact, there are other airplanes, which use the same propeller...the C-140 comes to mind, and I remember reading of a homebuilt that used a rebuilt P-3 engine (complete with props).

Thanks for all your help...my project is slowly coming together...I had to borrow my fathers old NATOPS flight manuals, in order to get some of the numbers, as well as, correct modeling of the cockpit.

rous