understanding prop size on my saito powered rambler 45----help
 

I have a saito 82a in a world models rambler 45, I am a novice - intermediate pilot,this is plane number 2, have done 3 flights with a 13x8 zinger and found it to be a bit 'course' for ease of handling,unless idle is very low( which it is not on this brand new slightly rich engine) she is easy to overshoot & she is quick on the ground, so I would like to go 'smaller' I have a 14x6, is this smaller or bigger ? I realise that the pitch is 6 instead of 8, but what does the difference in diameter do ????? what size prop should I go with for good sport flying ? I'm not looking for much speed at this stage, please explain what diameter does to prop performance.

secondly regarding the crancase breather, is it in order to run a pipe inside the lengh of the fus in order to get the crap out of the back instead of all over the underside of my plane ?

regards
John
New Zealand

RE: understanding prop size on my saito powered rambler 45----help
 

G'day John,
The 14x6 should be ideal for the 82a, check out this prop chart,
http://saito-engines.info/prop_sizes.html
As it runs in, you will be able to slow the idle down, so hang in there.

RE: understanding prop size on my saito powered rambler 45----help
 

thanks, good link-so larger dia does increase thrust, so which one is "higher geared" a 13x8 or a 14x6 or are they similar ?

RE: understanding prop size on my saito powered rambler 45----help
 

G'day John,
A 14x6 should give the plane a lower top speed, but about the same load on the engine, it should also be easier to slow the plane down for landing.

RE: understanding prop size on my saito powered rambler 45----help
 

When your engine is fully broken in and has established it's lowest dependable idle, then the pitch matters. Then the pitch will have an effect on how slowly the airplane will want to fly on landing etc.

A 13x8 prop will want to pull your airplane forward about 8" for every revolution. A 14x6 will want to pull it 6" forward in that one revolution. You engine is going to be idling about the same with either. Which prop do you think is going to want to pull the airplane farther/faster?

Now, all that said.............
Engines do different things when they're on different models. And props do different things depending on how effective they are. So...................

Try each one and see what your airplane does with your engine at your flying field (elevation has some effect) on the days you fly.

Your engine might not turn the 13x8 effectively on your airplane. Or it might not turn the 14x6 effectively. And that blows all the prop/aero theory right out the window, or into the slipstream. So you gotta test them both to get the answer that's true for your airplane.

RE: understanding prop size on my saito powered rambler 45----help
 

But the odds are that the 14x6 should fly your airplane slower when the engine is at idle than the 13x8 does.

But don't bet, just try it. Our hobby is good about our trying stuff. Seldom is anything worth trying much risk.

RE: understanding prop size on my saito powered rambler 45----help
 

BTW, have you looked up the range of recommended props for that engine?

What props are suggested by the mfg?

RE: understanding prop size on my saito powered rambler 45----help
 

You may want to use an APC prop as they weigh a bit more than wood. This will give more flywheel effect giving a lower, smoother idle. I used an APC13x7 for break in on my 82. Made two flights with a 12x9 yesterday, woo hoo! Mine has about a gallon through it now. Mounted sideways, the idle is incredibly smooth and low.
Get some time on it!

RE: understanding prop size on my saito powered rambler 45----help
 

go to google and download " aero design propeller selector". Safe download. This will show you the relationship between pitch, diameter, RPM and thrust as well as HP used.

RE: understanding prop size on my saito powered rambler 45----help
 

Saito-82a 13x8, 14x6, 14x8

I THINK THE MANUAL ALSO SUGGESTS 13X6, HELPFULL ANSWERS GUYS, AWESOME FORUM, THANKS, WILL BE GOING WITH 13X6-7 FOR NOW.

SO HOW ABOUT RUNNING THE CRANCASE VENT TUBE THE LENGTH OF THE FUSE AND HANGING IT OUT THE 'STERN' ?

RE: understanding prop size on my saito powered rambler 45----help
 

I, personally, would go with the 13X7. But then again I don't have any Saitos.
As far as the crank vent goes, try to keep it short. So no, you don't want to run it the length of the fuse.
What you can do is attach a piece of copper or AL tubing inside the cheek cowl (this plane does have cheek cowls right...?) and extend it down below the fuse two inches or so. Bend whatever radius you need in the tubing to be able to connect the top of it to the vent nipple with a piece of fuel tubing. If you nose over the metal tubing will bend - no harm done. Oh, use a slightly larger diameter CU or AL tubing than is commonly found in fuel tanks for easy breathing (5/32 or 3/16").
I've seen similar things done with other Saitos since they do "weep" a fair amount - weeping is not a bad thing!

RE: understanding prop size on my saito powered rambler 45----help
 

I had the 82 on my WM Mustang (similar to the rambler, I had that too) I tried several different props on it. I found that the APC 13x6 worked the best for 2 blades. Good speed and power combo, decently slow for landings. If I went to a 14x6 or a 13x8 it would work, but I wouldnt get as High rpms, and the range of the high speed needle became really small and hard to tune. I thought it really odd, because I had the engine on the Funtana 40 before, and it loved running with a 14x6 or 15x4W on that plane.
I also had really good results with the Master Airscrew 3 Blade 12x6.

RE: understanding prop size on my saito powered rambler 45----help
 

so what happened to your Rambler bad splice ? did you rate it ?

RE: understanding prop size on my saito powered rambler 45----help
 

I finally destroyed my rambler stalling badly coming out of a flat spin and smashing nose down into gravel. one of my more spectacular crashes really.... the wreckage, motor, tank and battery were spread out over about a 20' circle :p Wish Id had a camera....
I really enjoyed it. It was my second airplane too, perhaps a bit ambitious, but I had a lot of fun with it (of course, I did crash and repair it about 17 times...)
One big suggestion, now that I think about it. Put shims under the back of the landing gear blocks, to move the wheels farther forward when theyre down. I had mine tip onto the nose on 3 out of 5 GOOD landings :p

RE: understanding prop size on my saito powered rambler 45----help
 

You wouldn't be enjoying it so much if you had hit someone with an out of control plane.

RE: understanding prop size on my saito powered rambler 45----help
 

bad splice
have already shimmed rear of retracts 4mm she sits down really well.
shame that the internet police are active on this forum !

RE: understanding prop size on my saito powered rambler 45----help
 

Scratch,
you're right, Id have felt terrible. But most of my flying career has been out in the boonies far away from people because we got chased out of everywhere due to the noise, so I wasnt so worried. (and everywhere was the only other 2 flat spots without a ton of trees within 45 min drive) I've only been flying at a club field for about the last 4 months, as we finally have a club in our area with a good field, and I am very careful of people. I have basically crashed and destroyed one of my planes intentionally rather than trying to "save" it, at the risk of it coming Near the pits.

RE: understanding prop size on my saito powered rambler 45----help
 

Cavandish,
Got any pics of your rambler? Heres all that remains of mine :p

RE: understanding prop size on my saito powered rambler 45----help
 

nice

flying tomorrow, will get some then whilst she's still in one piece !

RE: understanding prop size on my saito powered rambler 45----help
 

wow what a plane, takes of in several feet and will do unlimited vertical !!!!!!! can't wait to re-cover & get rid of that silly
color scheme. maybe all yellow or red with some flairs ? I recon the cock pit screen is all wrong as well, would prefer if she looked more like a sig astro hog, what do you think ?

RE: understanding prop size on my saito powered rambler 45----help
 

ahh that brings back memories :) That was a really fun plane to fly, I may have to get another one now :p As for the canopy, I think it looks ok, but I left mine whole. I really like bubble canopies. Im getting more into WW2 birds, and Im always more attracted to the bubble canopies vs the razorbacks.