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Old Aug 14, 2012, 12:44 PM
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Thierry,

The 761s fit the servo tray cut-out perfectly, as do the MKS 6125H.
Jim

Quote:
Originally Posted by tiju000 View Post
Is this servo choice any good for the plane.

Airtronics 809 ( ailerons)
Airtronics 761 ( for the rest)

I would appreciate some comment of people using them and how they handle the task with time ?

I saw that most people go the MKS way ( new kids on the block).

Thanks
Thierry
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Old Aug 14, 2012, 01:23 PM
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Quote:
Originally Posted by Tuomo View Post
ST80 lamination was enough for winds in WC?

I flew carbon 68 planes in the strong winds at the World Champs and took direct tows in all the windy slots.

I can confirm they were plenty strong enough (Jaro Vostrel was certainly confident because I checked with him before the start of my mega windy slots and he just said 'do it it will be fine'). Just make sure you glue the ends of the snake outers to the fuselage sides at the canopy opening because I had MAJOR rudder flutter during one launch. But Samba build things properly so no problems during the flight or afterwards

As KDT has proved (is that you Keith?) the ST80 is also very good primary plane and worth every single penny but don't discount the C68 versions. Samba build these things incredibly well and the worlds has proven their strength and capability in all conditions
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Old Aug 14, 2012, 02:24 PM
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Canada, AB, Calgary
Joined Dec 2004
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So now your are making me think...

C68 or ST80 ?

Or a mix like C80 going to c68 and c40 tail....

I want to have the glider painted ( no pure black carbon if you see what I mean).

Thierry
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Old Aug 14, 2012, 02:38 PM
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United States, TX, Houston
Joined Aug 2006
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Neil,
how much ballast were you carrying in your C68?
I understand that there are no ballast provision in the fuse and all the ballast is in the wings.

Stefano
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Old Aug 14, 2012, 02:47 PM
Don't take your guns to town
vespa's Avatar
Thousand Oaks, CA
Joined Mar 2004
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Sadly, Samba used the same backwards servo tray as the Perfect so rudder flutter and other problems are imminent unless the tray is corrected. Therefore you might as well put a little DS11 servo on the rudder and correct the tray accordingly. You certainly wouldn't want to put the rudder servo on the wrong side of the fuselage and try to fly with a crazy bend in your pushrods. Samba, take a course in basic geometry! You can calculate the correct location of the servos in 5 seconds with a trivial equation. (Rudder arm length) * sin(rudder half-deflection) / sin(servo half-deflection) = servo arm length. For example, for a 12mm rudder horn, +/-40 deg rudder travel, and +/-45 deg servo travel the servo arm should be 12sin(40)/sin(45)=11mm. Add 2.5mm for the clevis width and that's how far the servo should be from the side wall.

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Old Aug 14, 2012, 02:56 PM
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Norway
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My primary were C68 that I got delivered at he worlds... It is plenty strong enough for F3J for sure. I flew it in the rounds we had 11m/s winds constant and more higher up. I should have flown my ST80 because I had more time on it even with some repaired parts (midair a month before WC). I had 2 bad flights in the finals because of that. Flying with 3mm instead of 1,5mm negative camber to get home. 1,5mm is excellent for coming home in windy weather while 3mm is good for zoom. 3mm is too much for coming home... Switched to the repaired ST80 and I had legs again.

We do know that ST80 is stiffer in torsion than C68 so might give better launches. But no testing to prove it. Both are anyhow very strong models with ST80 more expensive.

All tails are ST40. SL ones with small changes to make them lighter though so dont interchange.

The 75g SL joiner is only for extreme lightness of the SL version (you only save 25g). I use the standard joiner when I practice landings with the SL so I dont have to be afraid of it breaking. Landing is much harder on a joiner than launching... I have landed the standard very hard and my team mate busted up the fuse in a 4m "straight down" landing but joiner is still good.
I have only heard of 1 SL joiners broken so far and one with a notch on it so it was exchanged. The Italians have launched the SL in 8m/s on F3J tow but you all know those thermals can come thru or those mega towers ;-) So dont push your luck. It is mostly easy to see when a model is pushed too far or the installation was not good enough.

A good choice not mentioned here for most wanting light models is the LS (lightstrong). It uses both ST40 and C68 and will take launches in most F3J conditions (that are already hard for a model when the FAI limit reaches 12m/s).
The LS should be a performer in everything but maybe the mid-europe dead calm foggy mornings were a SL might get some seconds more. Yet still be good when the wind picks up.

OH btw my next will probably be another C68.. ;-)

Regards jojo
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Old Aug 14, 2012, 03:00 PM
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Norway
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Quote:
Originally Posted by stefanoc2 View Post
Neil,
how much ballast were you carrying in your C68?
I understand that there are no ballast provision in the fuse and all the ballast is in the wings.

Stefano
You can get a lot of ballast in the wings (860?g I think). I had the first ones with only 630g bras available so I used the joiner and in the extreme one round at WC also a 330g 10mm steel rod in the fuse (simple wooden screw to put it in). But it was a bit on the heavy side (I am ballast guy...).
You can probably make 6-700g of ballast for the joiner but I dont think it is needed for 99% of the competitions.

Regards Jojo
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Old Aug 14, 2012, 03:02 PM
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Canada, AB, Calgary
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Thanks Jojo,

got the message... C68 it is

Thierry
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Old Aug 14, 2012, 03:04 PM
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Norway
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Quote:
Originally Posted by vespa View Post
Sadly, Samba used the same backwards servo tray as the Perfect so rudder flutter and other problems are imminent unless the tray is corrected. Therefore you might as well put a little DS11 servo on the rudder and correct the tray accordingly. You certainly wouldn't want to put the rudder servo on the wrong side of the fuselage and try to fly with a crazy bend in your pushrods. Samba, take a course in basic geometry! You can calculate the correct location of the servos in 5 seconds with a trivial equation. (Rudder arm length) * sin(rudder half-deflection) / sin(servo half-deflection) = servo arm length. For example, for a 12mm rudder horn, +/-40 deg rudder travel, and +/-45 deg servo travel the servo arm should be 12sin(40)/sin(45)=11mm. Add 2.5mm for the clevis width and that's how far the servo should be from the side wall.

That is my first installation and it was remade because of that. So the picture is not Samba's fault but mine putting my servos in the wrong way and had to put in some balsa blocks to hold the pushrods to the side. But when it was done I still wanted to fly instead of fixing it and it launched well in 10m/s+ winds on the ice this winter. It was remade and I also put in a better elevator servo because the one shown got sloppy in the gears.
So the installation picture shows only lasted a few sessions.

Regards Jojo
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Old Aug 14, 2012, 03:14 PM
Don't take your guns to town
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Thousand Oaks, CA
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No, Jojo, that is not your fault. Samba cut the holes and they did so in the wrong place. The Perfect was made the same way and most installations look just like yours, bending the pushrods and blocking the ballast. I saw your other pic where you relocated the elevator servo to the rear as a workaround. That solves the problem very well in your case but many folks use a lighter servo for the rudder in which case it is a sub-optimal compromise. Apparently not enough people complained about the tray in the Perfect and so Samba will continue to overlook this unless people complain.
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Old Aug 14, 2012, 03:29 PM
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Norway
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Quote:
Originally Posted by vespa View Post
No, Jojo, that is not your fault. Samba cut the holes and they did so in the wrong place. The Perfect was made the same way and most installations look just like yours, bending the pushrods and blocking the ballast. I saw your other pic where you relocated the elevator servo to the rear as a workaround. That solves the problem very well in your case but many folks use a lighter servo for the rudder in which case it is a sub-optimal compromise. Apparently not enough people complained about the tray in the Perfect and so Samba will continue to overlook this unless people complain.
I dont understand. Both holes are the same size (you see I had to put in spacers in both) and I cut the pushrods wrongly as elevator should be the short one and with bigger horn. So I had to lengthen the rudder pushrod. Or do you mean that elevator servo should be in front?
There is no ballast tube in the perfection fuse. The screw hole you see I put in myself to accomodate extra ballast since I am a ballast guy...
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Old Aug 14, 2012, 03:48 PM
Bro
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Southern California
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Perfection

Hi,
Looks good to me...

B
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Old Aug 14, 2012, 03:50 PM
Don't take your guns to town
vespa's Avatar
Thousand Oaks, CA
Joined Mar 2004
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What I'm saying is that many people use a heavier servo on the elevator and so that is traditionally the forward servo. Also since the elevator servo uses a long arm it is useful to have a long unsupported pushrod run to accommodate the resulting lateral travel.

The elevator servo cutout isn't so bad but the rudder pushrod will be severely bent no matter where you mount it, especially if you mount it in the aft cutout as most do. So what I'm saying is that Samba made the rear (rudder) cutout slightly offset to the left when it should be greatly offset to the right.

Bob, your pic looks good but I'm guessing you can only use about half of the rudder servo travel.

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Old Aug 14, 2012, 04:03 PM
Bro
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Southern California
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Perfection

V,
Forward servo with left side pushrod is the elevator...
Offset looks pretty darn good to me. Same as my stock here.
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Old Aug 14, 2012, 04:13 PM
Don't take your guns to town
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Thousand Oaks, CA
Joined Mar 2004
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Yes, offset looks great, just like my Perfect. But you can probably only use half the rudder servo travel because the rudder arm is way too long so there's much more slop, less precision and less torque than there should be. So the options are to either deal with the slop and other problems with that crazy long servo arm or bend the pushrod like crazy and deal with that slop, binding, and blocking.
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