well, I'm not a newbie but I am sorta...
I've been flying since I was 8 and am now 22 but I haven't been in the hobby for the past 5 years...

Now that I have returned the first thing I did was go out and get an RTF so I could get back in as quickly as possible, it is an extra easy rtf from hangar 9....

Now I here is the question, Back when i was in it before I left the "old timers" at our field wouldn't dare change prop sizes...
a 40 size engine uses a 10X6 and thats it nothing else will work...

But now after reading these post on here I see what happens if you change a prop the affects and such but here is what I ask..

currently the engine has a mds .40 on it and a 10x6 prop...
the plane flys way to fast for a trainer setup it is constantly climibing even at idle almost and enough down trim where it shouldn't.. Also on take off I noticed it took it a while to "build up" speed for takeoof, a little longer/distance than it should.

What would happen if I put an 11x5 prop on it? would it slow the plane down + give better take off performance??
I guess basically what i'm asking is how do I know wich prop to go with? the 11x5 or a 10x7 or what??

I've even seen post on here about using 12x3.75 on 40 size engines?? If it would work I would have loved to use on on my old airmadillo with the .46sf so it could hover

well sorry for the long post its my first one on here, and trust me there are many more to come!
THanks!

definitely feel free to experiment with different props. the 11x5 will slow the plane down a little and help with landings. I have used 12.25 x 3.75 a lot on fun fly planes that I do not want to go too fast. A strong .46 can run a 12x4 but not in its optimum rpm range. I like a 11x4 prop on my .46 engine also.

and it ROCKS!!!!
I dont know if a bushed 40 would pull it very well though .
You might try some downthrust on your engine to get rid of the climbing tendancy.
John

what is confusing me is why go with larger diameter?
why not go with just a 10x5?? is it to keep the revs down??

also in the same respect if I were doing like a pattern plane and wanted to make it faster would I go with say a 9x7???

bigger diamiter gives more thrust, smaller pitch gives less speed.
I ran the 12.25 prop on a sig somthin extra and it would hover it no prob, would even pull it out of a hover (5 pound plane) The speed was still respectable. on the extra easy i am not saying it is the perfect prop, it was for my SE with the pro 40. But it will slow your plane down and give you great power for takeoffs and good slow landings.

BTW , i just realized.....Welcome to RCU!!!!!! come back and ask lots of questions, thats what we are about.

ok now for this, balancing a prop...
I have a top flite magnetic balancer....
I have never been able to balance a prop to where it will stay at any position..
is there any web site that goes into deatail about this?

Not much to it. Don't remove material from the back of the prop as it can change the pitch angle. Adding weight to a light tip also works and paint is a good choice. Do this all slowly.

Make sure there are no sources of wind (from the A/C or fan) as it will make it really tough to balance.

EXCAP232

Sounds like you also have a case of high idle as well. With a 10x6 prop on a 40 sized trainer using a 40 sized engine, you shouldn't be climbing at idle (unless your trainer is sub 4 lbs). You want your engine to idle as low as possible without going deadstick or trim the idle down as far as possible on your landing approaches.

sure ,try a 10x5, just watch the rpm,s. Don't like to add weight to balance a prop. it has a tendency to come off.
Have a goodun,John.

I have the Hangar 9 Xtry Easy myself. Although I haven't had any problems with climbing at idle, I put an APC 11x5 (was Master Airscrew 10x6) on last week. It made a tremendous difference on takeoff, cutting down the length of runway needed to get off the ground in half. In the air it also has some extra oomph to pull the plane around. You might want to give it a shot.

well since it was the first flight of it last week the engine did need to break it....
it keep overheating for some reason, but if you ritchened it up it would load up and die...
the last time I flew it I noticed that even with the trim all the way down it was idleing a tad high but not to much.....
I'm still thinking of the 11x5 prop though...

On balancing the prop I know that its not just wether one side is heavier but you actually balance the leading and trailing edge of each side of the prop, thats what i"d like more info on... Is there any website anyone knows of that goes into detail on balancing props??

and thanks guys for all the help! Glad I found this site!
cheers!

Only balanced 4 props, but found the hub to be heavy on one
side of all of them. Need to trim down the heavy side of the
hub or glue weight in the light side before they will balance.

I would add some downthrust. I had a plane like this when I began. Not a an uncommon mistake among newbies.