Prop for a 12jae FE

[ezhitz]

I'm wondering how do I tell if the prop is to small in dia. for a given size boat?
On my 12 size jae rigger i'm running a Neu 1506 5200kv on 2S spinning a x432 boat runs mid 40 mph
eagle tree show amp draw average 86 amps on a 2 minute run.Would going to a X435 be a better choice
giving a little more dia but less pitch maybe keeping the amp draw around the same.Or is that the speed i should
see from this set-up.I know if I use the online speed calculators estimate mid to low 50 mph makes me wonder if I'm
doing something wrong in my set-up.

riggerx632.jpg

[NativePaul]

I'm running a 2850 5280kv motor in mine with a de-tongued and backcut X435, haven't tried an X632 yet though just stock X435 cut X435 and Mshape Y535, x632 will be next.

How well does the 1506 fit the JAE.12? my 2850 doesn't quite fit and needs a small bulge in the hatch or an aftermarket hatch as seen here.

[ezhitz]

Thanks for your input my boat is scratch built not the kit the tub on mine measures 22" long x 3" wide x 1 3/4" deep.
Ready to run weight using turnigy 2S 30C 5000MAh is 2lbs 12oz or 1251 grams.I did put a dome on the hatch over the motor.


FE Boats 001 (Small).jpgFE Boats 003 (Small).jpg

[Boaterguy]

Have you tried changing the CG and strut height? it may change your setup.
depending on what calc you're using but it may not be taking slip into account.
Conditions may have an affect also.

[ezhitz]

Thanks Boaterguy I used the calc here on OSE and the Fast Electric Calc thats on the web I know they are only estimates but being out by 4-9 mph would be alot
i think.I know i nead to move the cg back a little if you use the 60/40 rule stated by Zipp kits.Its really is a fun boat to play with and try to learn more about FE I'm
not looking for saw speed by any means more curious if I was in the ballpark or did i do something wrong.It does give me a great oppertunity to play with props to see if
I can reduce the amp draw without dropping to much speed.
Thanks Jack

http://youtu.be/EGFiYqSpvAg

[NativePaul]

Its hard to tell with a video but I would say thats on a par with mine.

[ezhitz]

Thanks NativePaul I am happy with the way it runs but we always think we nead more LOL. I will try playing with a X435 to see what it wil do.

Jack

[Boaterguy]

If you are into it, try a slight back cut or a detongue, it might help get rid of some of your amp draw while not dropping and possibly increasing speed.

[eric_laermans]

Hi Ezhitz,
In Europe we run 2s riggers with 37mm - 39mm props with 1,4pitch (size depending on kV). Speeds are around 55mph and personally I try to keep the current down as much as possible and that is between 60A - 65A. I use a Lehner 1535/5 (4899kV Hi-Amp) and 37,5mm prop. Ready-to-race weight is kept down to an absolute minimum and this could save you a lot of amps. Ready-to-race weight is 1.100gr and hull length 65cm. The measurements are pretty much the same as your JAE, but I rebuilt it using CFK/ GFK where possible:

http://www.youtube.com/watch?v=Jpq1eH2KrmY

How is your Miss Supertest going?

[ezhitz]

Hi eric
thanks for your input.I think I should of used a neu 1509 4500kv instead a little longer can would handle a bigger prop.But I'm still going to keep working
with what I have. My son retired the Miss Supertest for now,he built a Whip 20 hydro and its been running great.

[jasoncyclone]

I have been using a sv27 motor and esc with a x440 prop on 6S and it is insane! I will be going doing to 4S because I think the 6S is to much....