Servos Suggestions
 

I am building my first pattern plane in 25 years, Focus II, nice plane, requires a little more work than most of the ARF I have had in the last few years. But, I am having problems with the elevator pushrod. First I build as the designed with the bearing at the end of the push rod, it seem like I had a lot of flex in the elevators. I messed with that for days, got mad pulled it out and put in two HS 77 low profile ailerons servos under the stab to run the elevators. They work great, but I have had to add about 5 oz
to the nose, man I hate that. But of course, the plane is over weight, I call it Ms Piggy. I am in the process of removing the servos and going back to a push rod., now, I am able to remove the nose weight. But I still have a lot of flex. The hs77 weight about 1.2 oz, the wires are about another ounce or so, the 4/40 push rods with ball end , it all added up. Can any some suggest some small lightweight servos that are up to the task for 2m elevators? I am going to try to fly the plane again this after noon. If it not to my liking I have got to fix it. I have only got a few weeks until my first pattern contest and need to get the plane sorted out. Thanks T green

RE: Servos Suggestions
 

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RE: Servos Suggestions
 

I had the same problem with my Focus II and i used a MX Bellcrank at the rear. And put a piece of foam in about the middle of the elevator pushrod to stop the pushrod from flexing.

RE: Servos Suggestions
 

Look under the thread Focus II by the numbers. Specifically post 46, It shows a light ply support for the pushrod scroll thru the thread farther and you will see a foam support also.

RE: Servos Suggestions
 

Thanks guys, two good suggestions, i need to look up the focus build post, should of done it before i flew the plane. I did just make a bearing about 3/4 of the way down the pushrod shaft, what a pain.. i have shorten the push rods to as short as i can get them, maybe this will work. D-bodary how heavy are the bell Cranks, did your focus seem to come out tail heavy? and I have used airtronic servos, I had them in my Altanta, I remember now, thery were about 3/4 the size of a futaba and about half the weight. the plane is still on the heavy side even with carbon tube and landing gear..I need to stop my wining and get to work. thanks again tgreen

RE: Servos Suggestions
 

or JR 3421's

RE: Servos Suggestions
 

Mine came out at 4.54 kilograms well under the 5 kilograms. I was using a OS140RX with a OS header and a ES Carbon pipe and landing gear. I used the stock Aluminum Wing tube.
Jr 7005 servos on Ailerons A futaba 9402 on rudder Can't remember the throttle and elevator servos. The elevator servo was full size can't remember on throttle.
The MK Bellcrank i bought at Central was pretty light. My scales do not read that low, not accurate anyways.
I used a Hitec Super slim receiver. Nothing exotic or lightweight for sure.

RE: Servos Suggestions
 

Hey Terry are you going to start flying pattern with us? Great!

RE: Servos Suggestions
 

What ever servo you decide on I would NOT reccomend the HS-77 for a pattern plane. My experience has been that they are NOT one of Hitec's better servo's. Good luck whatever you decide.

RE: Servos Suggestions
 

I second that Dan. No HS 77.
RC

RE: Servos Suggestions
 

I took the hs77 out, you are correct. they don't seen to have the same speed. but they were the lightest of all the servos I had. Worked on the pushrod set up most of the day,
I think i got it. going out in the morning. Gregg, I am going to try to fly pattern again, at least that is what I am going to call it, you guy may call it something else. tgreen

RE: Servos Suggestions
 

You might want to try a DEPS pushrod. Similar concept to the old nyrod, except the inner rod is solid carbon fiber, so there is no deformation with varying temperature. Look up a thread on the Focus Sport by Troy Newman for an explanation. Central Hobbies sells components for it. I make my own with .070" CF rod and nylon sleeves from the LHS. For the rod ends I use a 2" long .070" I.D. CF tube glued with CA to the last inch of the CF rod, then a piece of 2-56 all thread. This is for a smaller (8 cell) electric. For a 2m plane and 4-4o ends you will want bigger. It is light and solid.

RE: Servos Suggestions
 

Included here is the complete DEP's System explained from Central Hobby's. The left column of this article, will walk you thru the system. Nylon gear set below to convert the 3421's from metal.

http://www.centralhobbies.com/instru.../depsinst.html

Vince



Servo Gear Set: S321, S3021, S3121, S3121R by JR

RE: Servos Suggestions
 

You'll get it going Terry!

RE: Servos Suggestions
 

I flew a Focus II in Intermediate this year with the pushrod support that Dennis described. It works fine with just a tiny increase in weight.

Scott

RE: Servos Suggestions
 

Have anybody seen this site? It's great!!!

www.servodatabase.com

All servo options seem to be there