J'Tec 35% Extra Build

[MikeC3D]

What about the rudder servos, where were they? I would like to be @ 25#, but I dont think it will be with a 100cc in it.

[jtsails]

I originally had 2 servos in a airwild pull-pull tray but I changed it to a single servo (Futaba 9156) mounted in the tail. It would take some pretty extreme lightening to get this plane down to 25lbs with a 100cc and cans. The bare airframe as it comes out of the box weighed a little over 13.5lbs. The TMM Toc106 engine that I'm now using weighs 12 oz more than the original ZDZ 80 plus I have an extra header and can. I don't have an accurate weight for the plane now but I'm confident that it weighs somewhere between 26.5 and 27lbs. The other changes I have made are a bigger, slightly heavier fuel tank and putting the wheel pants back on. Also note that all of these weights are with carbon tubes and gear. The stock Al gear is very stout and the carbon gear from graphtec saves a lot of weight, same for the wing tube.
JT

[columbo]

Just figured out a way to fit more plane into my 4-runner. Remove one of the rear seats. That seat is hardly ever used anyway. I was worried that I was going to have to build this plane with a removable rudder. I will still have to remove one stab though. Now I might even be able to fit a modest size 40% in there. Nah, at the present I can't justify going any bigger than 35%.

[Kevin Y]

	Quote: Originally Posted by MikeC3D
	What about the rudder servos, where were they? I would like to be @ 25#, but I dont think it will be with a 100cc in it.

You can actually mount the rudder servos in either the rudder tray that is built into the fuse or in the tail, it will balance fine either way.

[FENWAYFLYER]

This looks like a nice plane hows everyone like it so far. I have been considering getting one too just do not want to come off the money with the economy and everything.

[columbo]

Hey, Fenway flyer. You need to come off the money so that you can help stimulate the economy , and I need to get started on this plane.

[columbo]

Finally got started on the Extra. Finished up the EF 30% Yak about a week ago, but it has been too windy to test fly it. Finished up a wing today. Took a little less than 2 hours. On the extra, I am using sullivan 8-32 heavy duty hardware for the aileron control surfaces with ball links attached to the servo arm. Had to trim a little on the hardwood blocks that hold the servos so they would fit. The aileron hardpoints consists of two hardwood plates with foam sandwiched in between. Used a leveler while drilling to properly align the control horn screw with the aileron. The hardwood plates on the ailerons are quite wide to accomodate a range of servo arm lengths. The main things to keep in mind is the geometry of the control linkages. Control horn pivot point at neutral should be right above the hinge line. Also the linkages should be oriented roughly perpendicular to the hinge line. I like the checkered pattern on the bottom of the wings.

[MikeC3D]

ANy new info on this plane?

[dbcaster]

Columbo,
I must disagree with your control horn position theory. Your linkages should be perpendicular to the hinge line at full throw not at neutral. When they are perpendicular at neutral you will be pushing away from the servo arm and not have the best mechanical advantage when you need it.

[columbo]

I haven't worked on this plane in a while. I finished one wing and quit, because I had another plane (EF 88 Yak) that I was working on. However, I am now getting started on this one again and will post pictures as I go along. I decided to give the DL-111 a try. I got it on sale at southeast rcengines for about $608 shipped. Couldn't resist.

DBCaster - That is the way I have always done it with no problems. I don't like having my linkages at an angle when the ailerons are in the neutral position. They remain perpendicular at full throw when the ailerons are in the down position, but in the max up position they are at a small angle to the hinge line.

[dbcaster]

O.k. what ever works One more note just as a warning. A flying buddy of mine just lost a 50cc. plane due to one of his servo arms braking in half. It was the same type you have on you wing. For the small extra price of an aluminum arm you may want to look at that as an option. I am not trying to nit-pick your setup, just passing on information on a problem I have seen first hand.

[MikeC3D]

I wonder why that caused a crash, didnt the other servo still work? What surface did this occur on?

[dbcaster]

It was a single servo on a 27% Extra aileron. There was about 2 seconds of flutter followed by a broken wing tube followed by complete distruction. The wing with the broken servo arm was the only thing on the plane that came survived. The arms may be o.k. on a two servo setup but why take a chance?

[columbo]

dbcaster,

You are probably right. I usually use the H9 adjustable titanium pro-links, so will install those instead. Being threaded along the entire length weakens the pushrod to some extent, though they are short. I am also changing the clevis to a more heavy duty linkage. Thanks for the recommendation. As the old saying goes, the chain is only as strong as the weakest link.

[columbo]

Hey dbcaster,

In the previous post, I thought you were talking about my pushrod setup. I am going to change my pushrod setup though, and will post pictures in a couple days. However, as for the servo arms, I have used those in every giant scale plane since I have been flying giant scale the past 5 years including a 33% Yak and a 31% Edge. Flew the Yak with them for 2 years and never had a problem. They are not plastic, but are the super strength arms made of fiber composites for giant scale applications. Are you sure your buddy had the Dubro super strength ones or were they cheaper plastic ones?