Four Blade Props
 

Why do you folks not use Four blade props on your Mustangs[sm=confused.gif]

Thay look cool[sm=thumbup.gif] And that is what a Mustang used.

You all do everything else to make the plane look scale, BUT you stop at the prop.?????????

RE: Four Blade Props
 

Kilroy 52,
I have not yet, but will try a 4 blade prop on my P-51 when I GIT R DUN. I hear that many engines overheat as they try to turn 4 blades. However, I have used many 3 blade props with no problems. We will just have to do our own experimenting. Good luck.

"Keep 'Em Flying!"
Flak

RE: Four Blade Props
 

Due to the high RPM that RC engines turn, a smaller diameter prop is required. The appropriate two bladed prop for the engines use is usually smaller in diameter than a scale 4 blade. If you were to use a 4 blade prop matched to the engine RPMs of most RC engines, it would be even smaller in diameter. About the only way to use a 4 blade prop that approaches scale in size would be to gear down the RPMs that the engine turns. This adds weight, cost, complexity, and power loss through friction. There are few choices to overcome these problems. RCV makes a series of engines that is internally geared and is capable of turning larger, close to scale, 3 and 4 blade props, but the engine is not common in the US. There are some gas engines that can turn three blade props reasonably, and I believe there may be a couple of places that make gear reduction kits.

Scott

RE: Four Blade Props
 

To put it simply: model airplane engines do not have the power to swing scale diameter 4-blade props.

For example, on a 1/7th scale Mustang with 65" wingspan, scale prop diameter is around 20". Even if you stick a large 50cc gas engine in the nose (which is impossible), you still cannot swing a 20" 4-blade prop. The RCV 120SP four stroke with a 2:1 gear reduction unit can only handle a 16" diameter 4-blade prop. On larger Mustangs equipped with large gas engine, it is possible to get close to scale props through the use of gear reduction, but performance will still suffer.

RE: Four Blade Props
 

OK, put a 16" dia. 4 blade prop on the 1/7th scale Mustang and try that! It's only 4 inches in dia. smaller.

"Keep 'Em Flying!"
Flak

RE: Four Blade Props
 

Yep, only 4 inches, which will be very noticeable. Even one or two inches is noticeable, such as the size different between a 12" and a 14" prop, or between a 14" prop and a 15" prop.

RE: Four Blade Props
 

Hmmmmmmm Everone says no you can't do it. Thats the same thing the guys at my feild said.
Well let me inforn you a little on what I have done. I have a Hanger 9, 60 size Mustang (Marie) it has a Saito 100 Four Stroke engine in it, I use a 15x4 Zinger Four Blade Prop.
The rpm is a little low about 8700 I will change to a one inch smaller pitch to correct this. However, the engine turns it with no proublem and does not run hot, the power is fantastic and the sound is great.
Also I have a Power-Line Hobbes 40 size Mustang (Duchess Arlene) it has a O.S. 70 Surpass II Four Stroke in it, I use a Zinger 12x4 Four Blade Prop on it and it turns 9700 rpm, (perfet) I like to keep my Four Strokes around 10000 rpm, Also this engine does not run hot.
Model airplane engines do not have the power to swing scale four blade props????? you are wrong there, at least in the 40 and 60 size planes,because I am doing it, and thay work fine.
The planes will fly a bit faster with a two blade prop. BUT this ain't about speed, its about looking scale, and thay do look cool. At our clubs last scale fly-in, out of the ten P-51s there
mine got the most attention, and everyone was surprised to see them fly with a four blade prop,
thay thought it was for static display only. And for scale size, thay are right on. And (Look Great)
Don

RE: Four Blade Props
 

Yes, they work fine, but are the props scale size (20" in diameter on 60 size planes)? I think not. Any engine can swing smaller than scale size 4-blade props.

RE: Four Blade Props
 

15" diameter 4-blade prop is no where close to being scale diameter.

RE: Four Blade Props
 

it would work but wound't be as efficient. don't some racers use a balanced single bladed prop for that reason? Plus you can only tell its four bladed when its not running, so in that case slap on a true to scale static prop.

RE: Four Blade Props
 

Yes, the most efficient prop for racing is single bladed with a counter weight on the other side. For static display, most people just use a scale Hamilton Standard 4-blade prop.

RE: Four Blade Props
 

15x4 spinning 8700rpm, equals a pitch speed of 35 mph, if it unloads to 9300 in the air. Don't go downwind on a windy day. :eek:

RE: Four Blade Props
 

You are right the 15" diameter is a bit off, But it looks right on the plane, as does the 14" on the Duchess. But some other things on the plane are not 100% scale, so it is somewhat of a compromise. Most of the scale planes I have seen are not 100%, so you try to come close.

Now I am not talking about you hard core scale guys about this. You guys are in a class all your own[sm=thumbup.gif] I am talking to the, Well it's kind of sort of scale guys, that there seams to be more of. All I know is when you put my planes next to the SCALE ONES with there two blade props, MY PLANES SHUT THEM DOWN;) And you can to lell that it is a Four Blade when it is running, you can see it and here it...

RE: Four Blade Props
 

Hello guys,
This thread is of interest to me since I'm in the process of building the TF 1/5 mustang kit. I'm going with the DA-50 engine and a four bladed prop. Ofcourse it would be great to have a scale size prop but apparently it's just not possible. What I have done is purchaced a Zinger 26X8 four blade and I'm going to cut it down to the appropriate diameter, The idea being that I'll have some width at the ends of the blades to give it a more scale look. The plane should come out to 22 to 24lbs. I was wondering if Richard L ,you could recommend what diameter I should cut it to for scale proformance.
Thanks,
Carver

RE: Four Blade Props
 

Well, all the math and mph numbers don't cut it. This plane is plenty fast. And I do fly it on windy days. And it will do just about every stunt the real one could do, and more. If I want to race it, then I will put on the two blade prop.

Everyone seans to be able to spit out numbres,pitch,rpm,mph, not enough power,and reasons why it can't be done. BUT my planes are doing it, thay are fast, fly great, and look cool.

And like I said, put ten Mustangs in a line, and the fact that mine have four blade props that thay fly with, and are close enough to scale diameter to look right, thay are most impressive.

Now I know that I will not get the prize for !00% scale. But I have to have the bigest towl to wipe off the drool. Because at a show, most people don't know what !00% Scale is..
Don....... P.S. I am new to these forum things so bear with me. Thanks

RE: Four Blade Props
 

Carver, I'm thinking you will need to cut your props down to either 21" or 22".

RE: Four Blade Props
 

Thanks Richard,
What do you think of the idea? How will cutting down the prop by 4 or 5 inches affect it's capability?

RE: Four Blade Props
 

Oh, and is this pitch correct?

RE: Four Blade Props
 

Carver, I would buy a 22x8 or 22x10 prop and round the blade tips instead of cutting down a 26" prop. Yes, the pitch is correct.

RE: Four Blade Props
 

Because of the labor involved or because the prop is lighter? I already own the 26 inch. The blades on the 26 are already fairly thin, I wanted to get the beef at the end of the prop tip and then round it out. I suppose I could always return it, it's unused. At 21 or 22" i'm thinking it will look great, but how do you think it will perform?
Carver

RE: Four Blade Props
 

Because of the labor involved and because you will be altering the pitch if you cut down a 26". I would get a 21x8 4-blade (with wide blades) and go on from there.

RE: Four Blade Props
 

Thanks for the tips Richard. Just one more thing; in what way will cutting down a 26"X8 alter the pitch? and also where is it possible to find a 4 blader with "wide blades?

RE: Four Blade Props
 

Pitch is specified at some distance that's a percentage of the total length of each blade (I can't remember what that percentage is). If you look straight down the prop from the tip, you will notice that the tip has very little pitch, and the pitch increases as you move closer to the root. Thus, when you cut down the blades, the equation changes.

You can try the standard Zinger 4-bladed prop if you are not able to locate one with wide blades.

RE: Four Blade Props
 

Thank you for your help;),
Carver

RE: Four Blade Props
 

the angle of an 8" pitch blade at the middle of a 26" prop is the same as at the end of a 13" prop..... ever seen a Prather Pitch gage ?

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