CrazyHerb

My Feedback: (1)

Here's a question:

I've always followed the rule of 1 oz torque per 1 sq inch rule with my surfaces and never had a failure.
This using NYLON gears....

My current design, has 3x30x1/4 inch balsa sheets (90 sq inch) surfaces (aerobatic sport 80 inch span).

With karbonite gears.....will the HS-475's be ok?

I'm running 2000 mah 6 volt nicad pack....
I know the torque rating is 76 oz on 6V...

Trying to keep the plane light instead of using HS-700's...but still simple (1 servo per surface).

So, what ya'll think?? It would be a good test of the karbonite gear train....which I've had flawless performance on my GSP/CMP Katana 1.40.

OR do I need to trim my surfaces to 2.5 inch x30 for 75 sq inches.

Thanks!
CrazyHerb

MikeMayberry

My Feedback: (1)

I would say that it is marginal. There have been some reports of failures in birds that size. One of the reasons is the 475 and 5475's gears are not as thick as the gears in the higher torque Karbonite servos like the 635 and higher. I would recommend the 635HB's instead.

Mike.

CrazyHerb

My Feedback: (1)

Mike,
Many thanks for the candid response. I agree that 90 sq inches is a little bit much for them.
Hence, why I asked...

While the 635's would fit the application....I'd rather just go all out (if you want to call it that)...and get the HS-755's at (183 oz) for less than what I'd pay for a 635...
Then, I could bump my surfaces up to "Fun-Fly" proportions...and still keep the simple (single servo per surface) design.

I can see where 635's would be needed if I didn't have the extra wing area (and power) to support the larger servos..but my designs are giant foamies...so, I just cut a larger slot for the 755s...NOW I just need someone to get them IN STOCK!! I watch servo city on a daily basis...hehehe..

Looks like the downfall of the 755's is going to be the speed (.23 sec)..."yup...I can move a BIG surface...but it's gonna take till tomorrow".... Sounds like UPS Ground shipping!! DOH!!

I am still working on the design (and building as I refine)...So maybe I can go the "conservative" route and reduce the area of my surfaces to 2.5x30 (75 sq inches).
That puts it in a much more managable range for the $19 HS-475's...which I already have...

I know I sound cheap....but these are foamies....(just really BIG foamies)...but I try to keep it "safe".

Thanks again, much appreciated!
CrazyHerb