Hi,
I'm considering a 40 size Extra ARF purchase. It's a proper Great Planes one.

For "sport flying" it specifies minimums of:

Elevator: 45 in-oz
Ailerons: 45 in-oz
Rudder: 70 in-oz
Throttle (Glow Setup Only): 20 in-oz

I'll get new rudder and throttle servos, but for the Elevator and Ailerons I already have fairly new Hitecs which are 42.00 oz-in @ 4.8V. I don't have any 6v RX bats for higher current. I'm trying to get away with using as much of what I already have.

Any downsides with going the 6 volt route for forcing more torque from them?

I do not do any aggressive stuff like snap rolls or hover. Just harriers, knife edge and basic acro. So can I just ignore that my Ele and Ail servos are a bit under the "minimum"?

Silly question maybe, but I have to decide before I order the ARF as I should include any new servos in that order for spending efficiently. So many decisions to make that I can't decide on this one

Thanks

I really like using 5 cell (6V) batts on my planes. I use cheap battery packs for my source for batteries.

[link]http://www.cheapbatterypacks.com/tstuff/v7/buildcustompack.asp?sid=1509819#[/link]

Frank

OK, well the Hitecs I already have go to 51.00 oz-in @ 6.0V. More than enough for ele and ail.

As I've been pondering this (assuming I go 6 volts), I also thought that maybe I'll fore-go the recommended 70 oz-in rudder servo and just not do any knife edges (not a huge fan of doing those anyway). Basically then 90% of my rudder use is take off and landing. So my rudder would be also 51.00 oz-in @ 6.0V.

Only remaining concern with 6v is that my Hitec prism RX took in RFI one time when a 6v BEC was used, but maybe it was just the BEC though (I solved it by changing the RX; but don't have that one anymore).

Maybe this sounds like demented logic, but I'm so sick of buying so much new stuff for every project. Just gripes me every time

Thanks for your input

If you are not going to beat on your plane,using 4.8 (lighter) and the servos you have,you will be fine.
Have solid no slop linkages and seal your gaps with some tape and the strain on the servos is lessened also.You can do KE and if the servo is weak you will notice blowback in flight and can get a better one when you have time and xtra$.
If you fly smoothly,meaning no full speed snaps,blenders etc,your stuff will work fine.

Thanks man. I was looking for some 3D flier informed opinion on what really the result would be.

So as long as my rudder servo does not fail or seize up, it's fine. I guess by blowback you mean that it would sort of slip... could be a little hazardous for flight though. Maybe I'll grudgingly get the 70 oz-in servo.

But if the ele and ail servos would be fine even at 4.8v (42 oz-in instead of 45), then sounds ok. Fanciest move I do is harrier.

Only remaining thing is, those sudden unexpected snap avoidance or recovery moves where it's just your reflexes jumping in before you can even think.

But I don't do snaps, blenders and all that... I like to relax

Thanks I have a better idea of it now (good tips there too), Cheers

The Harrier is not hard on the servos.

Is the Elevator operated by only one servo?,because a low torque single would be of concern.If there is 1 for each half its ok.

I looked at the manual...
On a budget a 6 volt battery might be best.
Or get yourself a stronger elevator servo.

i would go with hitec 475s(12.99) with about 70 oz torque on 6v, and std on throttle...... hobby people has a special on hitec servos

Thanks guys. Yeah I guess I need to just grin and bare it. The plane needs what it needs. And yep the elevator is just one servo.

Even if I don't do individual aggressive moves, there are often the sustained high G turns and such.

Forgot to consider new Hitec servos. Almost always good alternatives on servos from Hitec.

Once again, glad I asked

Cheers

So I think I'll go for 6 volt battery, my existing Hitec's which get 51 oz-in @6v for elevator and ailerons, and the recommended minimum rudder and throttle servos.

At 6 volt, the above will be at the recommended well-above-minimum required torque and good speed as well.

As for my Hitec prism RX, I could test that at 6 volt on a trainer before putting that in. If that's not ok, I'll just have to pull a Futaba FASST RX out of a small heli and then save up for a new FASST RX to replace it.

I'll perhaps try to get away with not getting a pitts muffler to save a little more. Looks like a normal 46AX muffler (with dubro extension) might fit inside the cowl. If I end up cutting up the cowl a lot, then I can get a new cowl later.

I suppose that's a fairly well balanced plan...

Cheers

I would go for a regulator and a lipo, way lighter, 6v, and you can charge in at the field, also you can use your foamy 2s bats

http://www.unitedhobbies.com/UNITEDH...oise_Reduction

46AX muffler fits but you'll need to do some cutting. Skip the pitts, if you upgrade, and go with either a Ultrathrust or a Jett muffler. Much more power that way. You'll gain about 2-3K rpm, but pay with your hearing.

I have a regulator but I remembered it's capacity wrong (I remembered it was quite low), but I realized just now it's actually 3 amp capacity. So I could have used that because 3 amp should be plenty. Too late as I ordered a new 5 cell nimh. Oh well. Maybe I'll still get a rx lipo if I really need to lighten it up (I don't have any 2S lipos already as I don't fly anything 2S).

I did end up ordering a pitts muffler a couple of days ago. It's a light weight SlimLine Q series.

So the only "light" components on the set-up will be the muffler and the 46AX itself (being the minimum size engine but still pretty powerful for it's size). Everything else (servos, etc) will be on the heavier side. So until I put a stronger 4 stroke on it, it won't be much of a "performer" I guess.

I think stranded servos will be fine. i have flown them on all sorts of glow planes that size for years on single elevator servo setup and never hand any issues i still think all this torque is over rated run them and you will be fine

Depends on what you are doing...

BTW, put your rudder servo up front, and you might want to consider a 2 stroke 61 or 91, that would be awesome, and much easier to run than a 4 banger.

I was thinking I'd leave the rudder servo placement as late as possible in the assembly, so that I can see what works out best for balance, but could be that the 46AX just won't be heavy enough to warrant placing it on the tail.

I already have the four stroke in question. It's several years old and has been used very little. Just didn't end up using it when I got it originally. To be on safe side I should replace the bearings in it since it's been sitting unused for so long and possibly corroding the bearings... hence why I'm using the 46AX initially. I'll probably need help from someone when doing the maintenance on the 4 stroke.