I am planning on a scratch built 35” span completely sheeted trainer. Can standard Futaba S3004 servos be used for elevator and rudder with standard pushrods and horns instead of micro servos and pushrods? Or would that be overkill? I am planning on a 400 or 450 Eflite outrunner with 20amp ESC.

I've had standard servos on a plane this size and it was overkill, (long time ago, was a flybaby designed for .074 power). 4 channel and I used 4 standard servos because back then micros were way too expensive. It barely flew with the .074 so I ended up putting a enya .15 on and it flew ok. In hindsight micros were the way to go. An few ounces makes a substantial difference on planes like this.

Wouldn't a 450 Eflite equal or better the power of a .15?
The size of this will almost equal the size of the [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXUS70&P=7]House Of Balsa Chea-Pass[/link], and the specs for that state that it can handle two standard servos.

I only need two servos so the weight shouldn't be a problem, seeing as the entire plane will be sheeted.

Steve,
Park 450 is a bit less than a .15, I have 3 right now and one is in a Herr Little Extra, I use HS 55's on Ailerons and elevators and HS 81 on Rudder.
AUW is 21OZ with a 3s 2100 lipo. Flies excellent with good speed and power, very good but not unlimited vertical. My first few flights the plane was at 26OZ,
and it suffered in the vertical dept. I would dfinitely reccomend the Park 450 for sport flying up to 25OZ. You could easily get the 25OZ AUW on the cheapass
if you use micros, and build light. Otherwise I would reccomend the Park 480.

I have Hitec HS-81 servos, I guess I will use them, but I would have preferred to use the Futaba. I just figured with the modifications of the fully-sheeted plane it would be best with Futaba.

Fuselage is going to be 24 1/4" length built entirely of 1/8" sheet balsa, including formers. Stab and rudder will be 3/16" sheet balsa.
Wing span is 35" and 6 1/4" wide and will be mostly sheeted.

Will weight about the same as the Chea-Pass, and that recommends a .10 engine. I believe the 450 will be enough.

The 3004's are lighter than the std. servos we used back in the 70's and 80's...before micro and sub micro servos. (there were small servos then, like Cannon, and Kraft KPS-12's, but they were too expen$ive for me at the time )
I built an Ace Upstart using a World Engines Blue Max 4 ch. rx. and 2, S-5 servos, and w/ battery and switch the radio alone weighed half a pound. My Upstart weighed around 22 oz. with a Cox TD .049


You should be ok...the airplane will have to fly (and land ) a little faster because of the higher wing loading, but it's do-able.
Try and keep the structure as light (yet strong ) as possable...strength-to-weight ratio is even more important when you're talking about small airplanes.

If you can keep the AUW to less than 20 oz. I would think the 400 would be enough? That would also allow you to get away with smaller/lighter batteries.

Edit: guess I typed too slow tonight...
Sounds like you're using pretty thick wood there...it will be strong, but kinda heavy.
The HS-81's are plenty powerful enough for that size airplane...I'd use those. And after reading the previous 2 posts, prob. also the 450 motor too.

The other issue is cramming all the equipment far enough forward to keep the plane from being tail heavy. An oz in the tail equals 4 ozs in the nose.

After much consideration and the responses I have gotten here I have reconsidered the thicknesses of the fuselage frame, rudder and stab. To keep the frame lighter I have decided to . . .
Build the fuselage framework and formers with 3/32" sheeting instead of 1/8", but will keep the fuselage top 1/8" sheet to blend in with the stab.
Build the stab, fin, elevator and rudder with 1/8" sheeting instead of the 3/16".

Steve,
Have you had a chance to enjoy flying yet, just wondering, because you have quite a hanger.
I am ordering a cheapass stick as soon as they are back in stock, I have an OS .15 LA sitting
around that I acquired in a trade.

No unfortunately no flying as of yet [][:@]. Had a family crisis last summer that is still not resolved (foreclosure and bankruptcy). I am hoping to join this year but will try to learn if I have to do it on my own.

My completed and ready to go hangar has dropped down to just two. A Kadet Mark II converted to electric and a PT-40 nitro.
I have built a Micro Telemaster, and a scratch built Micro Telemaster just to have something to do this winter. I may not fly either of the Micros, they don't have operating motors as of yet.

I am having someone check out the PT-40 sometime in the next week, and I will not attempt to fly the Mark II until I learn (came out too nice and was expensive to convert). If he gives the OK for the PT-40 that is the one I will use.

I want to build this plane so I can have a smaller electric to practice on in my neighborhood. I already have the motor, servos, and components for it, and the wood will be around $20, cheaper than a kit.