Are you going to use the aluminum frames with the bearing to mount the flap servo, Tuan?
I sprung for a set with my 4.0, and glad I did. Between that and the full sized 6125, I have not yet had to touch my flap setup since I built the plane, and its still quite tight.

R,
Target

Originally Posted by target

Are you going to use the aluminum frames with the bearing to mount the flap servo, Tuan?
I sprung for a set with my 4.0, and glad I did. Between that and the full sized 6125, I have not yet had to touch my flap setup since I built the plane, and its still quite tight.

R,
Target

Those would probably be a bit of overkill for the X's. The linkages are not so short like those on an F3B plane where the pushrod compression forces are huge and thus transferred to the servo arm, bearings, case, mounting frame, then skin.

I am doing the flap servos with the wood frame, but block them so they tie into the upper skin and the main spar. I would think this method yield less flex than using the aluminum mount without tying into the spar or upper skin.

The bearings would be beneficial as they do provide extra support, however the amount of time the J planes are in high speed mode is but a few seconds here and there and one never pulls enough flaps in the high speed case that would make the extra support of the external bearings a necessity if the rest are solidly installed.

Bottom line, for me at least, is that I would worry more about the arm slipping on the output shaft than the flex of that final gear if there was that amount of compression force on the servo.

I'd actually like to use some flat carbon pushrods with holes at the ends that a rod slides into. the rod is held in place by carbon tubes at the flap end and an aluminum servo arm. The thicker wing allows this system to work very nicely.
Like that in the picture courtesy of fly-up85

Ok.

R,
Target

I did a build recently with metal trays and extra bearing supports, added over 1.5 oz to the build, I don't know if they are worth it in F3J models.

That's what I was wondering. Thanks for giving the weight of the increase.

Joe

These guys have some nice frames, including some with a bearing. John at HKM-USA can get them.

http://shop.rc-electronic.com/e-vend...&c=1158&p=1158

I used the metal frame on JUST my flaps of the 4.0.
Each frame weighed 7g (I weighed them). I added 14g (1/2oz) to my plane, and helped prevent the shaft from rocking.
For me, the extra 1/2 oz and $35 was totally worth it.

R,
Target

Originally Posted by Silent-AV8R

These guys have some nice frames, including some with a bearing. John at HKM-USA can get them.

http://shop.rc-electronic.com/e-vend...&c=1158&p=1158

Aha! Now those look good, and you know the wood must be lighter than the metal frames.

Howdy,
These work quite well with most any frame..
http://www.soaringusa.com/External-B....0mm--4pk.html

Best,
Bob

Here are some pics.

Very nice work Tuan. You may be an fnnwizard but you have the heart and skills of an engineer. In the immortal words of Dr McCoy: "I know engineers, they love to change things."

Chris B.

Originally Posted by SoaringDude

Very nice work Tuan. You may be an fnnwizard but you have the heart and skills of an engineer. In the immortal words of Dr McCoy: "I know engineers, they love to change things."

Chris B.

Thanks Chris, you can definitely call it out of necessity that I try to optimize where I think it pays the most dividends.

One of my thought process on this (and I would love to hear the true experts' opinion on it as well) is that removing weight from the " 4 corners"... nose, tail and tips helps the rudder to yaw the plane quicker which in turn helps to keep the fuse on avg more inline with the airflow which keeps the airflow more perpendicular to the wing... especially in the low level saves.

We've all seen planes go on drastic diets in the last couple years and it's a great thing. However a big portion of that weigh is not proportional to the 4 corners of the aircraft so the moments of inertia for the aircraft has actually gotten worst. Couple that with a slower airspeed and now the rudder becomes less powerful in a given thermal. It also becomes much more non linear. We might have to kick the rudder more in the begining (reverse expo mix)

Couple this with a lot of people still not using their rudder thumb adequately (can we mention adverse yaw here and incorrect slip?) and you get the "too light" for right observations.

Most people won't realize this at all but on these lighter planes, we will need to mix in more rudder throws for the given ail throws becaseu of airspeed. Not only during roll maneuvers, but also during the steady banking because for the same amount of bank angle, the plane flies at a smaller diameter = more in rudder to keep that airflow perpendicular to the wing. How much more, I don't know right now.

I'll know in a week or 2 if the rudder of this new 3.8X might be on the small side or if it is large enough to be effective in the low level more turbulent stuff.

So, I am satisfy being able to get rid of any amount of weight at the front and rear of this baby... now what to do with the wing tips ....

Tuan, you're dead on. The fin size on my 67 oz X1 was marginal. Same fuse, same span, same planform, same fin and rudder, and my 53 oz X2 was vastly underfinned.

And you're also right, most won't notice it.

Originally Posted by fnnwizard

So, I am satisfy being able to get rid of any amount of weight at the front and rear of this baby... now what to do with the wing tips ....

Get the 3.5?

Tom

Originally Posted by Kiesling

Get the 3.5?

Tom

Hahaha, I was contemplating doing rds to the 3.8 tips as I did to my first and 2nd Xplorer to keep the ail servo in the center panel. If not then what servo linkages I would use (MKS 6125 minis or Atx809's or ???). Decisions, decisions, decisions, arhgg.

Originally Posted by Daryl Perkins

Tuan, you're dead on. The fin size on my 67 oz X1 was marginal. Same fuse, same span, same planform, same fin and rudder, and my 53 oz X2 was vastly underfinned.

And you're also right, most won't notice it.

Thanks Daryl for confirming this! So my observations aren't just from lack of thumb exercises this past year