YS91 questions (Full Version)

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AV8TOR -> YS91 questions (3/24/2002 8:44:10 PM)

I am interested to hear from those who fly the YS91 as to what is your favorite prop (brand and size) and what is the weight of the plane that you are flying with the YS91. Also what is the heaviest plane that you have flown with this engine? TIA



RLDIII -> YS91 questions (3/25/2002 8:54:58 PM)

I like the 15 x 8 APC on my YS .91 AC. It spins it around 9K +/- 200 RPM on 20/20 fuel, or even faster on higher nitro. Right now I have it on a +/- 7.0 lb clipped wing Sig 4*-60. Vertical is unlimited and it pulls like a tractor. A friend was just out at the field this last weekend with his Aeroworks Edge and he also powers his plane with a .91AC. I think he said that his weighed around 9 lbs, but he was swinging a 15 x 6 APC. It was really turning up with that prop (faster than I like to turn my 4 strokes) but seemed to be working well for him, and it REALLY pulled that Edge around with authority!

Lee



deputydog -> prop and plane? (3/25/2002 9:23:05 PM)

I typically use the APC or the newer Master Airscrew Scimitar series 14x8 turning about 9800rpm. I found this is the best all around prop for the engine. I've flown it on planes weighing anywhere from 6 1/2 to close to 10 pounds. I haven't personnaly used the engine on a "3D" plane yet but have used it on stunt planes. Currently have one on a Giant Scale Planes Peashooter and it hauls this plane around with authority.
I use YS 20/20 fuel and firmly believe that you need a prop that will allow you full use of engine RPM. The YS runs at higher rpm's than any other 4 stroke. The big one's (91 and higher!) like 10k rpm while the 53 and 63 really like to turn 11k. Anything less and you are not exploiting the full potential of the motor and actually making it work harder thereby shortening it's lifespan!

My Nickel's worth!



JohnW -> Prop (3/26/2002 12:14:46 AM)

I ran a APC 15x8 like RLDIII mentioned on my 91AC and had similar RPM, about 9K. For reference, my altitude is about 1200 feet and I run 30% heli fuel. The 91AC seems real happy with that prop. I had it on a ~15lb Decathlon and had just enough to hold hover for about 5 seconds and then it would start to tail slide.

I do not suggest going over 9.5K RPM with the 91AC. I'm talking static RPM on the gound, not the actual RPM in the air after unloading. Not trying to split hairs here because DD's 10K fro a 91AC is darn close to my 9.5K; however, 10K on a 120/140? :eek:

I own a 120FZ and two 140Ls and if they tach out much above 9K on the ground I have problems in flight... too much RPM. You can actually hear the engine miss once it unloads. The power band for the 120/140 is really geared for peaks in the high 8K range. IMO, underproping the engine to gain RPM is a waste of power not to mention it is hard on the engine. I typically try to keep the 120FZ at about 8800 RPM and the 140Ls at about 8500 RPM and my performace is awesome at those RPMs.

Check out YS's web site for more info [url]www.ysperformance.com.[/url]



AV8TOR -> YS91 questions (3/26/2002 12:21:11 AM)

Thanks guys great feed back, just what I was looking for. I am going to try mine in a 9-1/2 lb Edge. Should be fine for me.
Wow 15 lbs Monkeyboy! That has to be on the weight limit. How much runway for take-off?



JohnW -> Runway (3/26/2002 4:44:40 AM)

I agree with LadyFlier that there is no best prop for a engine. Prop should match the requirements of how you want the plane to perform while still loading the engine properly, i.e. stay in the proper RPM range. For my 15lb Decathlon, I personally liked how the APC 15x8 with the 91AC performed on that plane. I wasn't looking for unlimited vert in the Decathlon :D .

Didn't need much runway on the Decathlon... big semi wing with reasonable loading. I needed maybe a little over 50 feet on calm days if I guned it, little less with wind. Don't really remember. Sold the plane and engine last year.



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