Help with props for a FF.12

[Mark Leyde]

Some of you may have seen this also posted on RC Universe.

My son and I got out this evening with his FF.12. We have a Dynamite .12SPD motor and a 2.5 mac pipe. The pipe is set at 8.5". and using a SS 215 prop. This combo did not get us on plan. We toss launched it and would only get a bout 20 feet and stall. What other props would you guys suggest? We are running a 3/16 prop shaft.

Thank you,

Mitchell and Mark

 

[shoboat]

Mark,

I would start off with a X-438 or 1440 B/C reduced to 37mm.

A X-637 will work well once you get the boat trimmed out.

37mm is the trick for little 12 motors. You also need a better

pipe. Too much cup on the 215 propeller,reduce it down,

backcut it,and reduce some of the cup on the trailing edge

and it will work a lot better. Your cannot load these 12 motors

up with a lot of propeller and think they will spin up.

Good Luck Testing,

Mark Sholund

 

[Mark Leyde]

Mark, My name is mark also. My sons name is Mitchell. I was told the mac pipe was the best. Not so? I need a carbon one don't I?

Mark

 

[TomMoorehouse]

it should be able to spin up the 215. i'd guess the motor has problems before the prop

 

[Mark Leyde]

It could very well be that this little Dynamite just does not make enough power. I just tool it apart and noticed that there is a .02mm shim under the head. I also got a .01mm head shim in the box that the motor cam with. Think I should raise the compression by changing the shim?

Mark

 

[ek kustomz]

check the squish/clearance on the head it be between .006-.008 is where we run most of ours. I found with Mark S (shoboat)'s help that the smaller prop is definately the ticket. I was running the x438 with very good results. Also how are you measuring your pipe?? from the center of the plug or as the gasses flow. Make sure you measure the pipe including the length of the header. Mine was about 7.5. What % nitro/oil are you running?? hope this helps. BTW Listen to Mark he helped me get mine screeeeeaming.

Zach

Mark I need a pipe and a x437

 

[Mark Leyde]

Zack, I measured my pipe length from the center if the plug to the widest part of the pipe using a piece of wire. So I could follow the center of the header curve. We are using ODonnell 30% nitro boat fuel. I don't know the oil %.

We got out today again. Used a GR 36X55 prop. We did get on plane with some set up ajustments. Like rising the prop. I think I may have to much drag on the turn fin and rudder. Also think I my need to get a smaller battary pack. the 4 cells of AA seam heavy to me.

Mark

 

[ek kustomz]

I would say up you nitro if it is available 50-60% should be good. I run 18% oil. How many shims do you have under the rear boom tube or is it basically set as build? As far as the batt goes I run a 5 cell pack made up of 2/3 a cells weighs close to the same so I don't think that is the issue I ave also run mine with a 4 cell aa pack and had no problems. I have my strut set 3/8" from the bottom of the hull to the center line of the strut. I have 2 shims under the rear boom. I really think you may be a little under powered because of the fuel. When you run high nitro fuel (from what I understand) you are able to run the boat richer and get plenty of power and torque. When you run lower nitro fuel you lean the motor out so much to get it to rev and you take away from you torque therefore you ability to turn a prop.

I hope I am correct,

Zach