RICK9303

My Feedback: (172)

I just received my Focus 2 ARF, and have a few questions, most of it is straight forward, but the instructions do seem to be lacking. I did read Don's first thread on the build of the arf.

First there is no CG called out in the instructions, what is the range? If elevator and rudder servos are placed as shown, is there a balancing issue with a YS 160 and muffler pipe?

What torque of servos are needed, and what should the start up throws be?

Any suggestions on a rear hold down support for the Hatori muffler ?

Does the cowl need to be cut in the bottom for cooling, or is the exit to the pipe tunnel enough exit area?

Are most people running on board ignition for the inverted YS, or isn't this a problem?

Thanks For your help, Rick

jlkonn

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Oooops!
Just noticed this was Don's thread...
...never mind...

Don Szczur

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CG- I like mine forward. Basically with elevator servo in the fuselage, elevator servo in the fuselage, battery pack on top of the landing gear, this put the CG at like 7 3/8 inches but I'll see if I can verify that. I'm pretty sure I mentioned it either in this forum or the pattern build forum. I used a YS 160 on mine.

What torque of servos are needed, and what should the start up throws be?
Here are my servos used and control throws:

Ailerons low rate 9 degrees up and down. Expo 19 percent. High rate ailerons 11 degrees up and down, expo 26 percent. I used 9411sa servos on the ailerons, but either 9411sa or 8411sa servos will work for you. I tend toward higher torque now, so I'd suggest the 8411sa on the ailerons.

Elevator low rate 8 degrees up and down, expo 25 percent. Elevator high rate 14 up and 13 down, expo 50 percent. I used a single 8411 servo on elevator. Again, for today's plane I'd go with either the 8411sa or the 8611a servo.

Rudder low rate 1 inch (measured from the top of the rudder) with 44 percent expo. Rudder high rate 1 3/8 inch, 70 percent expo. I would suggest the 8611a for the rudder.

Normal flight is low rate, stall turns, snaps and spins on high rate

Any suggestions on a rear hold down support for the Hatori muffler ? I used a Brown pipe mount with double tie wrap for extra security.

Does the cowl need to be cut in the bottom for cooling, or is the exit to the pipe tunnel enough exit area? I opened up the bottom of my cowl so it goes on and off easier.

Are most people running on board ignition for the inverted YS, or isn't this a problem? I did not use on board glow. However, a remote glow connector (Central Hobbies sells them) is really nice and keeps your hand out from under the plane trying to connect the ignitor.

Good luck with yours. My Focus planes got me a national champion trophy, and I believe something like 4th place the following year. Its a pretty good flying plane.

RICK9303

My Feedback: (172)

Don, I noticed on Piedmonts web site that the focus in the picture has the elevator servos in the tail, any coments on this? I like the idea to keep push rods short, and than use a pull,pull rudder servo up midway in hatch area. Would think that balance would not be a issue with the YS 1.60 up front, with a muffler pipe. What do you think?
Thanks Rick

Don Szczur

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Elevator servos in the tail work better with regard to trim change in pitch due to changing temps, and simplicity.

Servos such as 9411sa or 3421sa are light and would work well.

RICK9303

My Feedback: (172)

Don, Could you verify the CG that you gave me? Do you have the tank over the wing tube? I think I'm going to put 9411s in the tail for the elevators, and a 8611 behind the tank, pull-pull for the rudder. I'm going to be using a YS`160DZ as you have. I did go thru the entire thread you put out {Focus2 ARF building by the numbers}, and no one ever mentioned the CG, or having any balancing problems. In my GP Patty Wagstaff Extra300S I have the tank on the CG, but had to move the CG forward by .625, over having the tank at the firewall. On the Focus2, it looks like the tank goes in the canopy hatch area, as it would not fit up by the engine box. The instructions don't show much, must assume you have built pattern planes like this before. As all my building has been Scale, or aerobatic planes, like Yaks, Edges, and Extras, it seems strange to me that basic setup instuctions, were not spelled out for anyone new to pattern planes, but I know the basics should be close to the same. If you can please confirm your tank and CG location, I would be greatful.
Thanks Rick

Don Szczur

My Feedback: (1)

OK, here is what I had based on my memory. The tetra 500 cc tank mounted sideways, that way it clears between the wing tube and the canopy hatch floor. This is from memory so you will have to double check dimenstions but I believe it will fit fine.

I checked around and my hard copies went away. I may have posted on NSRCA mailing list sometime in 2004 if they have it archived that far back. 7 1/4 to 7 3/8 inches from the leading edge keeps standing out in my mind in terms of CG on my focus. I just seem to recall it was in front of the wing tube. Let me know how this works out. You can't fly it too nose heavy. At least I never could. It always snapped well and the forward CG gave it a nice locked in feel during loops and lines.

You can move your battery forward as needed. I moved mine in the vicinity of the landing gear. But if you need extra weight you can put a larger battery even up by the firewall as needed to offset for the tail servos.

All the best..
Don