skrez

My Feedback: (15)

Hi Guys,
I have a new great running Saito 100 and APC 14x8 on a H-9 Spit . It flys the plane good, but I would like a little more speed. What would be a good choice of prop to speed the plane up . Would something like a 14x10 MA Scimitar be too much prop for this engine, how about a 13X10? I use 15% Omenga fuel.
Regards,
Frank

w8ye

My Feedback: (16)

A 13-8 or 13-10 would be nice

Harry Lagman

I have a Saito 100 /H9 Stang combo that is probably not too dissimilar to your Saito 100/H9 Spit combo as an overall package.

The APC 13 x 10 is the next logical step up in speed from your APC 14 x 8. The 13 x 10 loads the engine slightly less at static than the 14 x8 (about 9400 versus 9200 rpm) but due to its higher pitch, will unload less in the air.

With my combo, I found that the slightly better vertical performance of the 14 x 8 offset the slight speed advantage of the 13 x 10. The H9 Mustang ( and I assume the Spit) seems to be quite a draggy airframe even with the gear up.

liquid_TR

13x10 is a nice choice, but even better; Ive been running APC 12x10 with the saito 100 @ 10300 rpm. (omega 15%) - It really moves! 12x11 would also carry some serious speed.

Chancho

12x10, huh? I tried a 12x12 and never got it to unload. On my Revolver, 13x10 was great and I've been using a 13x11 with excellent speed. I may try the 13x10 again to see if there is any difference. The engine is only on its 4th gallon of fuel. I'm getting 9400 RPM on the ground and dumb it down to 9000 to let it unload in the air. Maybe I'll try that 12x10 for more RPM and speed? Hmmmm...

Thanks,

Phil

liquid_TR

13x11 is simply too much load for this engine IMO. Its more like a YS91 prop. You dont have to rich it out 400 rpm for unload. unloaded engine will consume less fuel anyway. 100-200 off peak is more than enough.

The distant full throttle sound of this engine is just exquisite.. Not to mention if there were two of them racing side by side..

Chancho

Thanks Liquid,

I'll run the 13x10 and see if I can live with that. I still want to try the 12x10. Anyone; What are the results from putting too much load on the engine, i.e., overloading? What signs does an overloaded engine exhibit? I apologize if that sounds stupid, but if I were to continue with the 13x11 should I plan on ordering a set of new bearings, new piston? The plane is doing some serious speed with this motor and prop combo. I'm running 15% coolpower synthetic. Besides speed, it has plenty of vertical and throttle response throughout the range is excellent. If it were overloaded, wouldn't it be sluggish, overheat or something? This is only my second Saito besides the 125 and I'm still fairly new to the 4-strokes.

You're right, the sound of a Saito out out sweet. It's nice to hear a fast planes without all the high end RPM pro-pitch-screaming. Almost better are the Saitos unique low putter notes on a slow speed fly by. I would rather prop it down (which I was going to do anyhow) and have it last longer than try to get every ounce of torque or speed out of it.

Thanks,

Phil

Ken6PPC

You already nailed it. If an engine is overloaded, it has slow spool-up speed, and overheats. It might also die when throttling up quickly. Overheating it and running it too lean are probably the worst two things you can do to a nice engine.

Don't be afraid to let it rev up into 9000 or even low 10K range. That won't be nearly as likely to damage it as running it hot and/or lean.

I bet more high quality engine (like your Saito) probably meet their demise by lawn darting than actually wear out. Bearings do get rusty and require replacement, but that is pretty cheap and easy to do.
(See [link=http://www.rcuniverse.com/forum/m_7334104/tm.htm]THIS THREAD[/link] for an example of what can happen if you put off changing bearings too long.)

Running a few % of castor is probably your best insurance against rusty bearings, and I wouldn't consider using fuel without it.

Not to say this is the ONLY fuel to use, but I use a lot of Wildcat 15% Premium Xtra. That has 18% oil, which is 80/20 synthetic/castor.

Chancho

Thanks Ken.

This is the university of all things hobby. They didn't teach me in calc, thermo, differential equations or anything of the sort - how to tune a 4-stroke, the best prop or properties of an RC engine.

You know? I tried music, violin, piano, and guitar earlier in life to no avail. Music takes an ear and rhythm. both of which I don't posses. I can't play basketball either. But when it comes to electronics, programming or something mechanical I can usually find that sweet spot. It may take a few burned out circuits, crashed code or locked up bearings, but I'll get there. Sometimes by pride, but it's cheaper and you can get their quicker by listening to the experience and wisdom of others.

I did notice that a few times when leaning out the engine and re-reading some Will Robison just a few hours ago, that an engine can run too lean - overload. (I am a big William Robison fan and reading his posts in the threads, he originally inspired me to buy my Saitos last year.) Presently I am tuning it down from a peak 9300-9400 to 9000 with a tach. I thought that the 400 rpm would be a safety in the back of my mind. (Running rich is better than running lean.) However a few times when it's been up and racing around a few laps, it slows on up throttle response - indicative of overheating. About 5 flights ago my throttle servo control rod came loose and the plane locked up with 3/4 to go of a 14 oz in full throttle. I was able to dead stick in. The engine was full balls till the end. I didn't notice the melted connector until I got home for a post flight inspection. It can't be good.

I'm going to put my 13x10 back on and retune. Though it is a rocket ship with a 13x11, I believe Liquid and other points to be indicators to follow the right path - that it is overloading.

I jumped in this thread because I own a Saito 100. I searched Google and it brought me hear. I hope this helped skrez or anyone else with a Saito and wanting speed, or to learn of others experiences.... As it all helps me.

Perhaps I understand overloading an engine better?

And me and a good buddy/fellow flyer are going round and round about the Caster Oild debate.

Thanks again, all.... All the respect to Will Robison, Saito, and fellow RC people. "God Bless Mr. Robison..."

Your comments hit home and were well received - May the force be with you!

Phil