Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

sPPED PROP FOR sAITO 91?

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Old 12-10-2004, 10:05 AM
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DLT
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Default sPPED PROP FOR sAITO 91?

I'm going to prop my Shoestring Racer (with Saito 91) with a prop to deliver more speed. I'm now running a APC 13x8 and it's moving prtty fast but I was thinking maybe an APC 12x10, 12x11 or 12x12. Any comments or suggestions. Thanks, Dave
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Old 12-10-2004, 12:24 PM
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Default RE: sPPED PROP FOR sAITO 91?

I have a EZ Models Voodoo with 91 Saito, it weighs 6lbs. 54 in wing span. It was clocked at 120, with a 12x8 APC. As soon as the ground dries up I have a 12x10 that I am going to try.



Thanks Jody
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Old 12-10-2004, 01:36 PM
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Default RE: sPPED PROP FOR sAITO 91?

I have a EZ Models Voodoo with 91 Saito, it weighs 6lbs. 54 in wing span. It was clocked at 120, with a 12x8 APC. As soon as the ground dries up I have a 12x10 that I am going to try.
what kind of rpm on the ground are you getting? i have a saito 91 that is going into a wm dago red and i was thinking of going with a 12 or 13" prop. I currently have a trojan T28 with a saito 91 and use a 14x6 (or 14x8??) with it.
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Old 12-10-2004, 04:49 PM
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Default RE: sPPED PROP FOR sAITO 91?

This is kinda basic for either the 4c or 2c engines.... applies to both.

For speed with that aircraft, keep the diameter to a minimum, and pitch the prop up to load the engine a bit more than you normally would tend to (on the ground).

For your set up, 12" prop is probably best. Id say go with the 12x10 as a baseline. Although you may want to experiment with an 11" dia if you can fine one with enough pitch (11x13??). Load it down with as much pitch as you can, letting the engine turn somewhere around 8800 to 9000 on the ground at peak. That is your target. Once you know how things work there, you can try loading it down closer to 8500.

The Shoestring is a fairly clean airframe, and will allow the engine and prop to unload nicely in the air.... usually will unload the additional 1000 rpm up to 10K. The higher pitch prop will happily unload as the plane accellerates. You will not want to let it turn higher than this in the air if at all possible.

The only issue I see is that most of the 12x10ish APC props are older pattern props, with somewhat wider blades. Would be nice to have a narrower blade 12x9 or 12x10 available for the speed applications.

Bear in mind, with the 11 and 12" props on the shoestring (and on the lil toni) a smooth takeoff and first turn are cricitcal. Its going to take a while to come up to speed. Do not get impatient... shallow climb...wait for the airspeed.

I received an email from somone using the jett 90L on the shoestring with a 'carved' wood 12x9 up front, and he states he has the engine turning 13K on the ground, and its seriously moving in the air. (no pictures so far).

Bob
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Old 12-10-2004, 10:52 PM
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Default RE: sPPED PROP FOR sAITO 91?

Hey Bob I am getting 9K on the ground with my YS110 14/12 APC. How much pitch could I get with a 12 or 13 inch APC prop?

With the 14/12 I can lift off in 10 feet and almost go straight up (WM P-51 60)
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Old 12-11-2004, 08:38 PM
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Default RE: sPPED PROP FOR sAITO 91?

The YS 110 is in a different league It runs as well as the YS120 we use in pattern 10 years ago. The thing has unbelievable power.

My old OS 91FS gets about 9K on a 14x6

In that particular case, It may be tough to cut down on prop diameter. It's a lot of engine, and as long as you are RPM limited (mechanical limit - just the nature of 4 strokes) it makes prop selection a bit tricky. But sincve you have all the HP in the first place, and you are pulling heavy pitch as it is..... Id imagine the 14/12 is about right for what you have there.
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Old 12-15-2004, 11:27 AM
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Default RE: sPPED PROP FOR sAITO 91?

Not sure of what rpm it is turning don't have a meter. Next time at the field I will borrow one and check it.


Jody
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Old 12-16-2004, 09:21 AM
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Default RE: sPPED PROP FOR sAITO 91?

I am running a 12/12 on my Saito 100 in my little WM P-51 (40). I set the rpms at 9600 and it screams.


ORIGINAL: MustangAce

Hey Bob I am getting 9K on the ground with my YS110 14/12 APC. How much pitch could I get with a 12 or 13 inch APC prop?

With the 14/12 I can lift off in 10 feet and almost go straight up (WM P-51 60)
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Old 07-29-2005, 12:26 AM
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Default RE: sPPED PROP FOR sAITO 91?

hi all,
I have a gp shoestring and it is beautiful. I have a magnum .91 four-stroke in it swinging a 14x6. I want to keep trying to get this baby faster. I bought a 13x6 prop the other day, i think this should give me more speed. If anyone has more suggestions about getting this plane faster, feel free to share info.

Thanks
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Old 07-29-2005, 12:27 AM
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Default RE: sPPED PROP FOR sAITO 91?

oops, i meant 13x8 prop, sorry[X(]
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Old 08-02-2005, 03:24 PM
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Default RE: sPPED PROP FOR sAITO 91?

APC lists 11-12,11-13, and 11-14 pattern props, so getting a bunch of pitch in 11" diameter doesn't seem to be a problem. In narrower 12" props, they list 12-11N, 12-12N, and 12-13N "narrow" pattern props. If the airframe is clean enough, one of the high pitch 11" props might be the ticket, but experimentation is definitely in order, as is watching your static rpm.

mIKE d.
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Old 08-08-2005, 03:49 PM
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Default RE: sPPED PROP FOR sAITO 91?

I still dont quite understand the whole 4stroke to go fast thing,,,,but I know that APC does make a 13X13N prop that might be the ticket for your needs. The part# for this prop is: LP1313N.
I have a QM40 pylon racer. As you may or may not know, they hit speeds in excess of 185mph. Thats out of a .40 engine,.....oh, did I say that it's a two stroke?
Just ribbing ya.....I'm sure your plane will move plenty fast enough for you to have all the fun you need.
I just got the new Minow by great planes....I'm going with the Webra Speed 1.20 two stroke on it. Similar prop selection as above. I intend "and suggest you do the same" to watch the head temp with an IR temp guage and use the tach to decide what is the max pitch and engine load, while listening to the beast in the air for potential leaning out conditions when the prop unloads.

Good luck in your quest for the ultimate prop!

BTW, I do like four strokes....Have a Saito .91 in my Ultimate Bipe.....just thought you should know!!!LOL
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Old 08-09-2005, 01:22 PM
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Default RE: sPPED PROP FOR sAITO 91?

Bob,
Thought I'd chime in about the YS110FZ vs. props. On the GP Lil Toni I'm using the APC 13/13N. On the ground it's turning about 9800. I'd like to reduce that to about 9000 on the ground but they don't make a 13/14N and I don't want to go to 12". It does unload in dives but I think it stays within the recommended 11K absolute top limit. I don't know how fast it actually is, my guess is 10-20 mph slower than a typical 424. It makes pylon turns much like a Q500 V-tail.
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Old 08-13-2005, 08:13 PM
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Default RE: sPPED PROP FOR sAITO 91?

help,
i mgetting 9400 easy with a apc 13x9 on the ground with saito 91
clocked at 81mph straight and level, i need more, but 13x10 chugs motor too much....
any ideas or others with same setup??
thanks
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Old 08-13-2005, 08:14 PM
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Default RE: sPPED PROP FOR sAITO 91?

forgot to mention it is ina GP Shoestring
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