gjeffers

jett, this setup will even start my saito 180 with no problem, you just have to make sure that the prop is all the way counter clockwise aginst compression and it will zip it around

blw

My Feedback: (3)

FFOURU,

A 3 bladed prop isn't necessarily inefficient at all. Look at all the 3 and 4 bladed props on full scale planes. There are advantages and disadvantages. You already pointed out the ground clearance advantage. A 3 bladed prop will most likely give you good braking action on descents and low throttle settings, as well as downlines if you try those. The proper prop could give you good climbing performance. I would be interested in how your prop performs on the .72. I've been holding off on them until I can find a good spinner with a metal backplate for my .72.

One of the top contest guys, I think Jason Schulman, has gone to 4 bladed props. He attached 2 APC 2 bladed props to get what he wanted. He was flying the circuit with this.

Jack211

The thing about forums is you don't know who knows. Take the 3 blade/4 blade props' efficiency question. They LOOK great, and I have SEEN full scale P-51s using them. That THEY do doesn't mean they'll work on models, too many variables.


Jack

FFOURU

Is the rule of thumb for conversion from a 2 blade to a 3 blade prop to drop 1" in dia and keep the same pitch???

FFOURU

I am told that the most efficient propeller would be a one blade, but they are rather difficult to balance ;~)
I currently have one on my Cub, right after it hit the ground!

car147

Hi

I have now had about 8 tanks of fuel through my Saito 180, what rpm should i be looking at running a mejlik 18x6 at around 700 sea level. so far she's running at around 8000rpm and still slightly rich top end.



Thanks.

Bipe Flyer

Like this?

http://www.bolly.com.au/models/glassone.html


It's like saying that high aspect wings are more efficient. Biplanes, which are very inefficient compared to gliders, still have their place. It's the same for props. A 2 blade fits most applications, but 1, 3 or 4 work better in some instances.

FFOURU

solafein

If you take a close look at the IMAC competition planes you will notice 3 and 4 blade props on just about everything. The prop range for a 72 is from 12*8 - 14*8, as listed on the Horizon web site. The MA 12*8 or 13*8 should work.

jasonlacey

I wanna join club Saito, excellent info here!! Thanks for the info Gary#23. I have a Saito FA 72, the cylinder being on the way to Clarence Lee for a new glow plug thread (ouch). My question is, as i dissasembled the engine i noticed the top of the piston was very rough is this normal?

gjeffers

welcome Jason, William Robison(the keeper of the thread) hopefully will be back soon and will add you to the club

before someone can answer your Q on the piston you really need to show a picture of just how much roughness there is.does it look like something bounced around in there or is it just a even roughness, there not polished or anything like that.

Bipe Flyer

Oooh, home made.

Pergus

I wanna join club Saito. I have a Saito 30, 180 and 220, and they run great

Thunderchild

I was told the ROT is DOWN an inch in diameter and UP an inch in pitch.

This is useful source of info: [link=http://www.bolly.com.au/book/content.html]The Bolly Book[/link] you may want to have a look at

Cheers,

TC

XJet

If it looks like it's been very coarsely sandblasted then you might have been getting detonation due to too lean a mixture or too large a prop.

I've seen a number of engines destroyed by detonation (not mine) and they all have very beaten-up piston crowns -- and the heads don't look too flash either.

Under normal operation, the piston should not be rough -- although it might not be shiney it should be smooth.

William Robison

My Feedback: (3)

All:

I had a gentleman wave a fist at me holding several $K, so I've not kept up here lately. I will catch up.
------------------------------------
Jason:

I will ddress your query before looking at the rest.

The piston crown should be plain aluminum color to a light brown, the attached picture doesn't show the true color because of the lighting. The upper valve pocket is close to the color of the entire crown.

If your piston has a deposit on it either brown or black it's an effect of the fuel and oil, not to worry about. On the other hand, if there are pits in the aluminum it's from detonation, as Xjet said.

As he said running lean and too much load will aggrravate detonation, along with too much nitro and overheating.

Please note that detonation and preignition are not the same thing - preignition is almost harmless, detonation can destroy your engine.

Picture is the piston from an FA-100, color is typical of all Saito engines running properly.

Bill.

FFOURU

"Please note that detonation and preignition are not the same thing -preignition is almost harmless, detonation can destroy your engine."

I have to disagree. Engine failure analysis is my "Real" job on full size marine engines. I see both detonation, and pre-ignition on a regular basis. You are right in that detonation and pre-ignition are different things, but one frequently leads to the other. Detonation will sometimes blow a hole in the top of a piston. Pre-ignition will melt the edges of the piston, sometimes all the way down to the ring land. In a single cylinder engine, it most likely will start metal transfer to the cylinder and seize before it gets down to the ring land, but in multi cylinder engines, the other cylinders can keep the engine running and cause advanced damage to the effected cylinder. Pre-ignition is often caused by a carbon speck that acts like a glow plug in the 2 cycle marine engine, but the glow engine already has the glow plug in place. Continued operation in a lean condition will raise the cylinder temperature, and start the melt down process.

w8ye

My Feedback: (16)

Lets not get carried away here with a bunch of follow up motorcycle and boat pictures. This guy very well used a boat engine picture to demonstrate his point. Which is good.....

But, any more pictures of something not Saito might get deleted.

In the past with this thread, one explanative picture would open a endless barrage of pictures of some guy's favorite ride. This would lead the thread away from the original subject.

Enjoy,

Jim

William Robison

My Feedback: (3)

FFOURU:

Granted, sustained preignition can cause damage as bad as that from detonation, but in a single cylinder model engine it seldom lasts long enough to do any as the engine will usually quit if it continues. So in that light, talking about our ordinary Saito engines, I stick by "Almost harmless."
-----------------------------
Jim:

It doesn't matter that he posted a picture of a piston from a boat engine, it's a good illustration of his point and very much on topic.

Bill.

FFOURU

OK, no more boat pistion pic's, but the damage and the reason for the damage is the same!

dougwill

Bill
Just an additional comment on the stuck valve problem. I had a similar thing happen to me a couple weeks ago on a almost new Saito 82. I fueled engine up thru a fueling valve, attached glow power and hit engine with starter. It fired once and the spin freely. Additional info: engine is inverted. I did not prime engine after refueling, but I also did not spin engine by hand prior to starting to check for flooding. Engine is in a UCD with the fuel tank a little higher that it should be. Also when I remove valve covers, they were full of fuel. I just touched the valve spring and it came free. I have flown 2 or 3 flights since then and it seems fine. I hop no damage was done.

Doug

Tripp2loo

My Feedback: (15)

Guys,

I have a Saito .91s that Ia m trying to do an in cowl installation of in my little 60 size Waco.
I have added the 45Degree header, and all fits in nicely, but I need to extend the muffler out of the cowl, in the rear opening. This means I need an extension of around 6 inches or so.. (Story of my life [sm=lol.gif]). The Dubro deflectors are all too short.
Any ideas what I could use?

Thanks

Tripp

XJet

Is it my imagination or is moderation sometimes a little pedantic on RCU? The piston image was very useful as it showed clearly the damaging effects of the phenomena we're talking about.

If we're too pedantic then it will simply drive people away by making this place seem sterile, cold and harsh.

Lighten up a little -- it's only a hobby and although this is a Saito thread, threats of deleting non-Saito images is ridiculous when they have something to contribute to the issue being discussed

(waits for *this* post to be deleted)... :-(

JettPilot

My Feedback: (6)

I totally agree with X-Jet, overmoderation will kill a forum and take the fun out of it. Unfortunately, all of human history has shown that once a person gets power it usually goes to thier head and it is abused. It looks like we have a moderator here that is just itching to hit the delete button and exert his authority over us.

It seems that everyone in this country supports free speech, until its them in control, then there is always a "reason" or "excuse" to tell everyone what to say or not to say....

JettPilot (also waiting for this post to be deleted)...

gjeffers

Doug, how is it going, on your flooding ucd, i have came up with a solution to that very problem and think it will work in your application as well.after im finished fueling via fueler valve i just pump out about 2 cranks and then pull my suction line from the can and then pump back a stroke of air and if there is no fuel in the line it wont siphon to the carb till you crank on her and it will fire right up, although you may get a small hesitation when the air pocket hits the carb it shouldnt die, mine dont and this works great for me

later and good luck!!