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What RPMs are you getting on OS 25 FX?
Posted: Wed Sep 29, 2004 5:44 pm
by Bill Goldberg
I have a couple older OS's a 25FSR and a 25F ABC. We are flying combat for fun 2610 with some 2548 rules...like a 10x3 MAS prop to even things out. I'm deciding whether to upgrade my older OSs to FXs. So looking to see what RPM others are getting...
My OS 25FSR (OS #8, 10% Omega, MAS 10x3 prop) turns 16.1-16.3K RPM
the 25F ABC is a few hundred RPM less, but not fully broken in yet.
How do those numbers compare with the FX?
Thanks, Bill
Posted: Wed Sep 29, 2004 6:13 pm
by Ed Kettler
The RPM limit for 2548 is 15.5K. We usually run the APC 10x3 props, and see 14-14.5K. The APCs make a lot less noise than the MAS.
Good luck!
Ed
Ed Kettler
RCCA 533
AMA 730493
Plano, TX
Posted: Wed Sep 29, 2004 10:20 pm
by lightning
Bill, try an APC 10x3 or an MA 10x<b>4</b>. The MAs are typically underpitched. Measurement of an MA 10x4 with a pitch gauge shows a true pitch of close to 10x3.
That's why we are testing the Limited B concept with MA 10x<b>4</b> OR APC 10x3 props. They seem very comparable. (Except the APCs break easier!)
I hate to think what the true pitch of an MA 10x3 is!!
These props will probably bring your rpms down to below the 15.5 limit too. MY OS 25FXs have been getting low 14Ks with either prop, 15% nitro and stock mufflers.
Keith J (member OGC)
Radio Control Club of Detroit
RCCA #622
Posted: Wed Sep 29, 2004 10:32 pm
by crashhappy
my 25FX is turning 14,800 on 15% power master with 10x3 apc. motor only has about 30oz of fuel run through it.
Tony Duprie
Posted: Thu Sep 30, 2004 11:54 am
by Bill Goldberg
Great info guys...Thanks.
I didn't realize the MAS 10x3 is underpitched. I have both MAS 10x4s and an APC 10x3. I will try them this weekend and post the RPMs.
At least I am hopeful that the FSR isn't giving up too much to the newer FX.
..Bill
Posted: Fri Oct 01, 2004 10:08 am
by sgilkey
Bill, for our Limited B demos, we have typically seen rpm in the 14.1-14.8k range, usually centered around 14.4-14.5k, on 10x4MA or 10x3APC, with nitro ranging from 10-25%. This on stock mufflers, usually with the baffles out.
I haven't tried one myself, but the 10x3MA has been pretty much universally hated by those who have tried it. Try the 10x4, or the APC 10x3. They both perform very well, the APC probably slightly better.
Scott Gilkey
Posted: Fri Oct 01, 2004 3:19 pm
by Bad Dawg
I am not going to say I hate the MA 10x3 on a stock motor, but it is pretty slow and they don't climb well. I was getting up close to 16K on a 25FX with an MA 10X3 and the performance was in the neighborhood of the second year SSC birds. Certainly flyable, but you had to plan your moves or run out of momentum.
NUNC AUT NUNQUAM
Mark V.
The perpetual 'newbie'