Piddler

I have recently "assembled" a Hangar 9 P-51 60 Miss America with a Saito FA100. What is the best 2 blade prop size for this combo? Can someone suggest tuning techniques? This is my first 4 stroke and I want to make sure I have it tuned properly before I put it in the air again. The engine stalled on a failed landing approach and I stalled it turning it around. Nosed it in the ground and busted the cowling and punched the engine through the firewall. There was no damage to the fusalage other than the firewall. I was pretty lucky. The plane is all back together now and I don't want this to happen again. I realize the the engine quiting is not the only thing to blame for the crash, skill had alot to do with it (First Warbird). Any tuning help is appreciated. Is 4 stroke tuning different than that of a 2 stroke. Pinch the fuel line and listen for slight rpm increase and make sure it trasitions good and tilt test. Any help is appreciated.

Thanks in advance,

The Piddler

Piddle-waste time; spend one's time idly or inefficiently

William Robison

My Feedback: (3)

Piddle:

There is no one "Best" prop for all circumstances, but on your plane I'd try a 14x8 to start.

Until your engine has a few hours on it you wont get a rock stable low rpm idle, and being inverted the engine's idle setting is a lot more sensitive than when upright or on the side.

To keep it going until it's fully run in and adjusted, use the idle trim on your tx to set the idle up around 2800, and don't pull it back until after you've landed.

Bill.

BarracudaHockey

My Feedback: (11)

The low end needle on my 100 came burbling rich from the factory, needed 3 or so full turns so it would idle w/o fuel pouring out the exhuast.

XJet

I run a Thunder Tiger 91FS in my 60-sized mustang and have settled on a 12.5x10 prop for it.

The 14x6 gave unlimited vertical but flew too slow for my liking.

A 13x8 flew faster but the plane was still well down on speed.

The 12.5x10 is perfect. Nice and fast -- although I've lost the unlimited vertical (but who really needs that -- 1000 feet straight up before stalling from level flight is heaps!

Harry Lagman

Piddler (interesting handle BTW)...

I have the exact same ARF/engine combo as you and Bill's advice on the prop is spot on - an APC 14x8 seems to perform best on mine. It pulls about 9200-9300 static.

The firewall on that model is quite fragile - don't ask me how I know...

You have to tune the low end as lean as possible while sustaining a reliable idle and transition. Mine idles at about 2000 rpm and has done that since burning its second tank. I would wager that your low end is still a little rich.

Runtime will improve the Saito's reliability somewhat.

Don't be afraid to experiment with the low end adjustment in pursuit of reliability. Check that the tappets are in spec, use an OS Type F plug and consider 20/20 fuel as well.

Good luck.

Piddler

With the help of your replies and some additional research from other posts I have a plan. I will be staying with 14x8 Master Airscrew prop. I realize that the APC prop is more efficient, but I like the look of the Master Airscrew prop a little better.

1. Set the high speed needle by determining peek rpm with my tach, then back off or richen 200-300 rpm's.

2. Go to idle and lean the idle mix to raise the idle RPM, continue to lean until there is no rise in rpm's. Richen the idle mix 1/8 turn from there.

3. Double check idle mix with the pinch test. The rpm's should remain steady for a couple of seconds before the rpms increase. If it revs immediately, it is too lean, richen the idle mix.

4. Idle the engine for 30 seconds then rev the engine and ensure a smooth transition. Good idle should be trimmed to around 2,000 rpms.

5. High speed needle should be around 9,200 rpms with APC, not sure about my Master Airscrew.
I will probably double check the high speed needle with the pinch test also.



Thanks to Bryan for this post.

http://www.rcuniverse.com/forum/fb.asp?m=2743431

William Robison

My Feedback: (3)

Piddler:

All fine except the pinch. If the rpm rises when the line is pinched you're on the rich side. If lean the rpm will fall immediately.

Bill.

Piddler

Is step 3 refering to a pinch test on the low end or high end, or can you do it for both?

William Robison

My Feedback: (3)

Piddler:

Pinching works at any rpm. Immediate rpm drop indicates a lean condition.

Bill.

Cyclic Hardover

My Feedback: (3)

"Will" is right on.

P-40 DRIVER

I'm assuming you put 4 or 5 tanks through it; according to the manufactures directions, before you tried to fly it. I would set the top end about 500 rpm rich using a tach and set the low 1/8 turn at a time until it transitions well. reset the top end again to 500 rpm rich and set your idle rpm to something it will hold on the ground for a long period of time. Go fly, It should run well and transition well. I have found that Saito's leaned to much on the bottom end will die coming in for a landing or right after landing. After some air time lean the top end out 300 rpm rich. You must use a tach for accurate tuning, you cannot do it by ear. More experienced pilots use different methods but a tach works every time and theres no guess work. Saito's set up right are dead reliable, but remember you are just 1 or 2 clicks away from having it set wrong; they are that sensitive. 14/8 prop is the best for that setup.

Piddler

Thanks, hopefully we get a warmer day around here soon, so I can get this thing tuned and in the air again.

Piddler

It got up to the mid 50's today, but 20 mph winds. I only got the engine tuned today. Got the low end set, then the high end maxed out at about 9,700 rpms and richened to about 9,200 rpms. Transition is good and the fuel econmy seems to be extremely better. It idles alot better now. It has a reliable idle around 2,200 rpms.

Can I tune my two strokes the same way?

Thanks,

Piddler

William Robison

My Feedback: (3)

]Piddle:

Yes, the two strokes can be done the same way, and they are even easier because they respond much more quickly to changes.

Bill.

Nitrodan73

My Feedback: (12)

I have been trying all these methods and I cannot get mine to stay running below 3200 RPM with a 14X7 MAS prop. I can get it down to 2200 if I leave the glow driver on it. I switched plugs to see if it was fouled and it work ed for a couple of minutes but then it started giving me trouble again. I had this engine in my corsair and it ran fine until I put it in my mustang with the engine upside down. Now it's nothing but trouble. PLEASE HELP! I used to have an article from Horizon that gave awesome directions on how to get your 4 stroke tuned but it's not on their website anymore.

Cyclic Hardover

My Feedback: (3)

Is it a new engine?

NM2K

My Feedback: (14)

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Yeah, once it gets high enough that you can no longer see the model clearly, any vertical capability after that is a moot point! <G>

Nitrodan73

My Feedback: (12)

No, It has had about 2 gallons through her already. What are the factory settings so I can go back to them and start over? It has been a good engine up to this point. It all started when I tried to get a better idle and I set it back to what I thought were factory settings but I ended up even more lost now. I had a good article explaining how to fine tune a saito but I've lost my printed copy and now the webpage is no longer existing...

Piddler

I haven't had many chances to fly this year, but went out last night and flew the Hangar 9 P-51 w/Saito 100. I had good smoke trail up to about half throttle and anything after that there was non. I flew for about 8 mins at half throttle and ran out of gas. I'm hoping I can solve the problem by leaning out the low end a little and richen the highspeed.

mscic-RCU

My Feedback: (6)

If you haven't changed the fuel tank, you might want to consider it. I have split three of the H9 Chinese tanks. They all split at the neck. Go with a Sullivan round tank, 14 to 16oz. I have the same plane/engine combo also. I have a custom Keleo creations header on mine, just awesome!!!

Piddler

Will the Sullivan 16 oz go in with no modifications?

http://www2.towerhobbies.com/cgi-bin...?&I=LXFU40&P=7

P51-Fun

My Feedback: (6)

I have the same plane/engine combo and am using a APC 14x8 prop and saito 20/20 Powermaster fuel and this plane haul's butt!! I was thinking about trying that Kelco Header on my plane. Do you have any pic's of yours you'll like to share??? and any trouble with the header's? Thank's

Hobbsy

My Feedback: (102)

While this is not the pipe you're getting it shows the excellent quality and fit. I Teflon taped the threads and there are no leaks.