I own a YS120SF and I would like to know what is the maximum thrust I can have with this engine?
Also, the YS constructor propose to me a 16 x 8 APC and some other people told me to put a 15 x 8 APC. According to you what should I use for the best thrust?
Please note that it is to put on a 8.9lb plane.
The previous owner of the engine told me that it turn at 9000RPM with a 16 x 8 APC. Do you think it is true?
Finally, what would be the better fuel to use?
Thanks alot.
Gilles

Gilles,

Buy yourself a fish scale and measure your own thrust? Just tie it to the tail of the plane. Thr reading will jump around due to the vibration and you will have to take an average.

The Y-S 91 will turn a 15-8. I just got through running one before dark. The 120 shouldn't have any trouble with a 16-8.

Enjoy,

Jim

my plane is under construction and i want to know how much thrust i can have with my YS 120
I know the metod w the fish scale but am not able to test that now because a have o lot of work before my plane is ready to fly
that s why i ask this question and with yours reply a will able to know the thrust of my engine and if necessary modify my plane weight

The YS 120 has no problem swinging a 16x8 prop at 9K rpm. It will give you around 15 lbs of static thrust. I have a YS 110FZ in my 12 lbs TF P-40, and that engine provides the plane with almost unlimited vertical.

If u want pure thrust ( Attn: Thrust never means speed-observe tugboats-) u should use max available -allowed diameter on prop.Speed wants more pitch but could loose thrust.

Gilles, the APC 16x8 on your YS 120 SF will haul a nine pound plane with ease, plenty of vertical authority. You don't need to measure thrust with that combination, just mount the prop and fly it. If you're new to YS engines, you need to take some time reading Troy Newman's threads and the YS Support Forum here on RCU. Do not use less than 20% synthetic/20% nitro fuel. A number of fuel brands mix a YS blend, and they all work. If you can't find a YS 20/20 blend, use a helicopter blend. More nitro is fine, but don't go below 20%. Don't use a castor blend fuel. Don't use after-run, just run the engine dry at the end of each flying session.

YS 120 will swing APC 17x6 @ 9500 rpm, which also yields about 15 lb. of static thrust.

I have burn 2 gallons in my YS 120 SF and I have nearly the same RPM a the middle of throttle then full open may be the regulator setting is too rich
wath you thinking about that ?

YS110 turning an APC 16x6 @ 9,750 RPM (max peak is 10,300 RPM), using Cool Power 30% heli ... awesome fun for my 9+ lbs Funtana 90. I would not mind a bit more power ...

Gilles - try to prop the engine to get it to turn at about 9,500 - 9,750 RPM. My YS110 is not very impressive when it turns at 9,300 RPM, the difference in performance between 9,750 and 9,300 is way too obvious. Again, what sort of a plane is yours? If its an aerobatic plane like Extra SU then go for 16x8 for a start, if you are going for something like a pattern try the 15x10 ... I got a 14x12 for my YS and I wonder what sort of a plane would it be for? Pattern too?

My plane is Extra 300 Carl Goldberg a know if i use another prop my old 120 SF can turn more but YS manufacturer said do not turn this engine more then 9000

Gilles - Your CG Extra 300 will be so nice with the YS120! Will be good to run a 16x8 on her, can it 3D? As for max RPM this is the thing ... YS says something like the YS110 is between 9,000 - 9,500 RPM only. Support forum here says run it at 10,000 RPM ... for me running at 9,750 RPM gives good power and the engine is not that hot ... about 220F only.

I don't think the YS 120 likes it if you run it above 9300 rpm. A 16x8 prop would be perfect for that engine.

By the way, you might want to ask Dave Shadel in the YS Engine Support Forum about max rpm and ideal rpm for the YS 120. I'm curious to hear what he has to say.