Off the shelf 3- blade props.

I am trying to ease into the three blade prop group. I want props that are ready to fly right off the shelf without any modifications.
I don't want to cut down or repitch anything right now. The thought of screwing up a $30.00 - $40.00 prop does not sit well with me.

The 3 blade props will be used competatively in the intermediate flying class. Glass, Nylon or Carbon fiber it does not matter to me. I just need a good start to get me on my way using 3 blade props.

I fly mostly OS40FP's, on profiles except for my Top Flight ARF Nobler which will have a LA40. The FP40 run just fine with a Zinger 12/5 or 12/6, the LA40 uses a 11/7W.

Any help in switching over to the 3 blades props will be appreciated.

Thanks,
Mike Clark

Generally, you want to go down in size 1", while keeping the pitch the same.

Example, when I was running my FP40 with a 3-blade, I was using a MA 9x5 3-blade prop, as my engine ran perfectly with a 10x5 MA. The MA prop is also relatively inexpensive, at around $5-6 each (or at least it ws last time I priced them).

I'd say the best thing to do is just go ahead and buy a variety of standard 3-blade props and try them all to see which is best. Be sure to balance the prop, as well, and you shouldn't have much trouble.

Hey SteveB,
The 10/5 and 10/6 MA's you were talking about, is that a Master Airscrew 3 blade prop?

No, those were 10x5 and 10x6 2 blade MA props.

Go with 90% of the diameter of the 2 blade props. For a 12" this would be 10.8"

For a 4 blade prop use 81% of the 2 blade diameter.

The 3 blade props are heavier than a 2 blade of the same brand which will make the plane a little more nose heavy.

It should be noted that if you buy a Bolly or Eather 3 blade you will probably have to balance it, but you really don't need to mess with pitch or whatever. They work fine "out of the box". They are not cheap, but work well without any creative adjustments. Most of the re-pitching or blade changes come for guys trying to get the last ounce out of them. But stock is fine.

What advantage do you anticipate in going to the 3-blade props? Since you're already swinging 12" props with your FP (sounds like one of Len's stump pullers) you should give the Bolly 12.5 x 5.5 2-blade a try. There's nothing else close to it on my FP40. If you order your Bollys from Bolly North America http://www.bollyprops.com/index.html you can order them already balanced so you just take the prop out of the package, bolt it on and fly.

Best, Hoovie

Thanks Guys,

Ground Clearence is all I hope to gain.

Top Flight ARF Nobler.
I am using a LA40 on this airplane, with the standard (Large) wheels that are supplied with this kit. I will have about 3/4 of an inch clearence between the prop and the take off surface. Now taking off from grass, 3/4 of a inch clearence and you could be cutting grass or worse. That is using a 11/7W Zinger not a 12/5 or 6.

The New Tom Morris Cavalier.
I just finished building, I believe is set up to fly with a Aero Tiger 36. Why, because the prop shaft to flying surface will not accomidate a 12 inch prop, unless I use three inch wheels. I could move the landing gear location forward just behind the tank area, but the center of gravity is greatly effected.
I did perform this move with the last Cavalier but only after a severe pancake landing made it manditory.

The Brodak Orenital.
Both a friend and I have one of this ships, mine is unfinished, his is in pristeen Shape and beautiful. The airplane has a inverted FP40 in the nose and the performance is unbelieveable. However this ship will not snap to verticle in squares. triangles or the hourglass. Now don't get me wrong this bird will fly but the 90 degree turns do leave a lot to be desired.

From reading Leonards information in "You prop is to big", is leading me to believe that the prop which is a 12/6 Zinger is applying to much of a gyroscopic force on this airframe, which I believe is hendering the turning radius. Can this be happening?
will a three blade turn this airplane into a killer and if so why would the forces be different for the three blade prop?

Thanks Guys
Mike Clark
(MikeC)

See if you can get ahold of a couple of Grish Tornado 10-4 3bl.

They're cheap and effective--Scott reise set up on the FP 40 run well and you will be able to tell the difference in the turn.

Curt

Brodak used to list them in their catalog--don't know if they are still available. I got mine from Sheldons.

(snip)
>From reading Leonards information in "You prop is to big",
>is leading me to believe that the prop which is a 12/6
>Zinger is applying to much of a gyroscopic force on this
>airframe, which I believe is hendering the turning radius.
>Can this be happening?
>will a three blade turn this airplane into a killer and if
>so why would the forces be different for the three blade
>prop?
>
>Thanks Guys
>Mike Clark
>(MikeC)

Actually, what I think I said was "your prop is too small, your nose is too big." Where is the CG on the plane? We never had a problem with the airplane turning because of the prop being too big. And we used a 13 inch 3-blade on a 570 square inch ship. I don't see where your set-up should be a problem on a 555 square inch plane. If anything, there wuould be a side to side precession problem with the larger prop. However, you also have "P" factor which actually counters the effect of precession in a moving plane. There will be effects of one or the other, yes, but not nearly as great as one may think. I would be more inclined to blame either a too far forward CG (quite possible with an FP 40 in this plane) or inadequate lift (translating that the plane is too heavy for the wing area). Try moving the CG back a bit to see what happens. If you are using a tube muffler, go to a tongue muffler. Or wrap some solder around the tail wheel (removing nose weight is better than adding tail weight). Just remember you may need (probably will) to narrow up the spacing on the handle when you do so.

Leoard,
I do stand corrected. I went back to read the article again and found out that I had misquoted your title. OOPS

Mike Clark
(MikeC)

Randy,

You can get Bolly's already balanced. Eather's come stock balanced perfectly.

The Master Airscrew thee blade 11x7 true pitch is 11x5. The pitch on all of the three bladed MA props are way off on the low side. The Evolution trainer three bladed prop is 10x3 ½. These measurements are with my pitch gauge.
Willis

LAST EDITED ON Feb-18-04 AT 08:26 PM (CDT)
 
>The Master Airscrew thee blade 11x7 true pitch is 11x5. The
>pitch on all of the three bladed MA props are way off on the
>low side. The Evolution trainer three bladed prop is 10x3 ½.
>These measurements are with my pitch gauge.
>Willis

Willis...Pat Johnston reported the same thing about the MA 12x6 3 blade, and he likes it and used it (with just a little rework) on his SSW Magnum/ASP .53. That would indicate that it would be worth trying on ST .60bb, 2Star .60's and similar. However, I'd stay with a 2 blade if possible. Making a longer landing gear is cheaper than buying a $45+ carbon prop...and if it works, a spare. Steve

PS: Regarding the Tornado 10-4 3 blade, OFB Mike Haverly has tried them, & I tried one. Nothing good has ever resulted from them for us. Others have better results; dunno why!

LAST EDITED ON Feb-25-04 AT 03:07 PM (CDT)
 
Someone correct me if I'm wrong, but I thought the plane should be turning really good before you ever started blameing the prop.
1. Nose heavy?
2. Hinge lines sealed
3. Elevator travel
4. Ail. travel
5. Good consistance engine runs with power.
6. Leadout position
Thanks

>>The Master Airscrew thee blade 11x7 true pitch is 11x5. The
>>pitch on all of the three bladed MA props are way off on the
>>low side. The Evolution trainer three bladed prop is 10x3 ½.
>>These measurements are with my pitch gauge.
>>Willis
>
>Willis...Pat Johnston reported the same thing about the MA
>12x6 3 blade, and he likes it and used it (with just a
>little rework) on his SSW Magnum/ASP .53.

That was the prop I sent Pat. I pitched it at 4.5 on my gauge. It also worked pretty good on the Saito 56.