I finally went all out on prop testing yesterday with my Phoenix Extra w/OS 55ax. It has always flown well, but not vertically and didn't have the power I thought I would have with it. I have tried 13x7, 12x7, 11x8, 11x7, and finally found out that the 12x4 is my new favorite prop! She would tear holes in the sky with the 11x8, but would not accelerate verticaly like I wanted. The 12x4 did it. It still seems to have alot of straight line speed as well. I have the same prop on my decathlon w/46fx and I should've tried it sooner. The decathlon doesn't want to fly on an 11x7, it needs alot of torque.

Valuable lesson in there for ALL beginners, I think:

Note that Brett didn't say one thing about RPM, or give us any estimate of flat out speed, or anything else. Everything in that post was couched in terms of what HE WANTED FROM THE AIRPLANE.

Rule #1 of props : The prop that makes the airplane fly the way you want it to IS THE RIGHT PROP.

Well said gb

Another prop that "might" be worth trying is a 13x4 APC Sport Prop
http://www3.towerhobbies.com/cgi-bin...?&I=LXFGV3&P=7
It may or may not work well for your combination, but, it's only about 5 bucks to give it a try.

As already noted, though, the "best" prop is the one that work the way YOU want. My opinion of "best" only applies to me.

Perfectly said!!!! [sm=thumbs_up.gif]

Ken

Thanks, Minn and Ken. Can't take credit for it though...it's a lesson taught to me by the LHS owner way back when.

I've learned the wisdom of his words, though. Go out to the field with ANY engine in ANY plane, and for every other pilot out there, you'll get roughly 234.987 "suggestions" for the "best prop" for that engine and airplane. Some will suggest certain sizes, others certain materials, others certain brands, some will combine all 3.

Yet...in the end, all that really matters is are YOU happy with the airplane? That "Bob's Prop World 24x8 wood/CF laminate Wdiget-foil prop" may, indeed, give you the highest RPM on your G-62 in your PW Extra. Doesn't, however, change the fact that you want the airplane to go slower and climb better.

So Brett did it right, imo. Just grab a handful of props (within reason of course...let's not accuse me of advocating a Xoar 23x8 on an OS .40 ) of every conceivable make, model, type, shape, configuration, and size...and go to it.

Eventually, you'll find as Brett did...props DO make a noticeable difference, and SOMETHING out there is bound to fly the plane "better"...from YOUR point of view...than any other prop.

Viola...you have just found 'the right prop'.

A friend of mine is running this prop on his OS55 in a Profile. It seems perfect for his needs. Fast acceleration and good speed. Give it a try.

i like the 12x4 apc for verticle performance as well, and 11x7-8 for spee

I have a new TTPro 61 that I'm going to put on a Tiger 60 that I'm building.
I dont have the info in front of me but it only gives two prop recomendations. one for break in and one for flying... How do I know the full range of props that I could try with this setup? size and pitch..

I would start with the recomended prop but Like was said, props at this size are cheap and I would be interested at some point in trying other sizes...

thanks

Steve

I had a TT-61 Pro on a 60 size trainer. I mostly used Omega fuel with 10% nitro and 17% oil. I tried the following props on it:

11x7 - worked fine for takeoff and flying but my engine idled fairly fast at the time and my instructor usually had to kill the engine to get it to land.

13x5 - when the engine was very new it tended to overheat with this prop. Never tried it after the engine was fully broken in.

12x6 - seems to be a good 'all around' prop for .61 two stroke engines. My trainer would land with this prop and it seemed to give a good mix of speed and power.

13x4W - This prop made the trainer feel very powerful. It seemed to almost jump off the ground when I gave it throttle. One negative was that it took a higher throttle setting for just flying around so it used more fuel per flight. I liked this prop on my trainer but it was to expensive to use at the time. I was trying to learn to land and tended to drop the nose at the last second. The "wide blade" props cost $8 each. I broke 3 in 1 day so I went back to the 12x6 that cost $4.

I like the 12.25X3.75APC on the 55 OS. It may not be the perfect prop for every application but it's worth a try.

David

One of my former students was flying a 14 X 6 on his OS .55 AX at the recommendation of the LHS. It was on a GP Cherokee and the performance was dismal. It could barely get out of its own way going down hill with a tail wind and a .46 powered version of the same plane flew circles around it. I told him I used to fly 11 X 7-1/2 on pattern planes and to try and 11 X 7. Once we put the 11 X 7 on, that .55 AX woke up and proved to be the right combination for that particular plane.

Hogflyer

The 14x6 is even outside the suggestions given by OS. 13x7 is the biggest in the manual. I can't imagine how bogged down the engine was.

Yup, the 10x6 on our GP42 was nothing, but switching to an 11x5 woke it right up.

Jack

A prop is a personal thing with certain dependencies such as airplane - engine - flying style - personal opinion

I just happen to have a Big Box O Props for testing.
Can't wait to get my TT GP42 out for a flight , it is one of my favorites.
Mine is modded , ,,,,,just a little.

I see some of those old style in that pile of props

if i ever need props i'll just call you
isnt a 12.25x3.75 more for a 46 sized engine ?

o since were talking props what is a good torque prop for a rimfire 35-30-1250
right now im running a apc slow flyer 10x7(tower only seguest 10x7).
i can get great vertical since the motor is way more engine than the plane needs (gws slowstick)
but one throttle click i climb, one lower i fall.
i was thinking 11x4 or 12.25x3.75
i just dont want to fry my motor.

The 12.25 X 3.75 prop is a 40 size control line prop but most are used on 40 size R/C 3D planes you see them on the 55's and also some people use them on the 50-56 size four strokes

One your rimfire you need to use the "E" series props. 11-4 or 12-4

i have thrown a MAS, top flite wood, and apc slow flyer(the electric one). all 10x7. on the plane
i actually liked the wood one, but needed it for a .46 engine and broke it...so i need to buy a few more.
none have caused the engine to over heat, so far.

Props are a personal thing - If you like it, run it

got that
simplified question
will a 11x4 (or apc 12.25x3.75) give more or less load on a engine than a 10x7
i want to try them, just dont want to fry my motor

Jimmy, it's not just the electric motors you have to worry about, but the Battery and esc also. I use a watt / amp meter
and test my props before flying. check the speccs of your motor and esc and make sure you never exceed the limts.

Example: my sig little extra has a Park 450 outrunner rated at 14amp continuous. I use a 20 amp E-flite ESC. I have the plane
propped to pull no more than 18 amps at full throttle (10x7 apc slo flyer). I propped down to 10x4.7 and got 16 amps full throttle
and around 12 amps at cruising speed 3/4 throttle. Battery is a 1300mah rated at 20C so it can handle 26 amps continuous.
now that I know what I what my limits are I can experiment with props in this range 10x3.8-11.5 slo flyer until i find a prop that
gives me the performance I want (perfromance measured by feel while flying)

i know
im fine for the batt 20c (3's) lipo (might be 15 not sure/doesnt matter, im still fine never use 15c)
i usually fly on like 4-5 clicks of the throttle thats how overpowered i am

my motor is rated to 30 amps
but i only have a 25 amp ecs
so in theory i shouldnt be able to fry my motor? (granted, surge current, ect)

35-30-1250 specs

http://www.electrifly.com/motors/mot...ire-35-30.html (it only has a test for a 10x7 prop, and its drawing 27 amps at 11.1v)

SPECS: Aircraft Application:
75-100 Watts Per Pound
Trainer & Sport Performance Weight Range: 3.3-4.4lb
100-150 Watts Per Pound
Aerobatic & High Speed Performance Weight Range: 2.2-3.3lb
Over 150 Watts Per Pound
3D & Extreme Performance Weight Under 2.2lb (my gws weighs a pound, 2:1 power ratio)

Motor Diameter: 1.38" (35mm)
Motor Length: 1.18" (30mm)
Shaft Diameter: .16" (4mm)
Shaft Length: .65" (16.5mm)
Lead Length: 3" (76mm)
Connectors: Bullet type, .14" (3.5mm) diameter
Max. Constant Current: 30A
Max. Surge Current: 35A
Max. Constant Watts: 333W
Max. Surge Watts: 390W
No Load Current: 1.2A
Input Voltage: 11.1V
RPM/V (kV Rating): 1250
Weight: 2.5oz (71g)
Suggested Propeller Size: 10x7E



btw i have a bunch of gws 10x4.7e props from a old motor would those give me more torque?
this is getting way to complex.
i just need to know if a 11x4 or 12.25x3.25 will load a engine more or less then a 10x7

So I am not the only one who tries a lot of props?!?!?! Bad thing is I just bought a OS 1.20AX and did not have the right prop for it. I had to go buy two more to try.

David