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thermaldoctor

Osprey f5j build log 1

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thermaldoctor

Well the Osprey test model is going together well. All parts fit and finish very good. Back in the old days i would have said there is a bit more to do than with other models such as fit your own control surface horns but these day many manufacturers leave it all blank anyway as they dont want to commit to a conventional linkage set up in case people want to put IDS. Anyway the Osprey has very nice molded carbon fibre tunnels onto the top wing surfaces for a conventional linkage at the control surface end. Thus you have to fit your own (supplied in kit) cnc'd G10 control horns. Works well and is easier to fit.

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I used a hybrid method which i believe combines the best of both worlds for a low speed low parasitic drag thermal soarer.  I combined the IDS system at the servo end which is by far the best solution as you can run pushrod pick-ups far closer to the servo hub for better torque and resolution without the hassle of grinding out an arc on the metal clevis to clear the hub of the traditional servo output arm. Plus the 1mm hardened pin on IDS is better than a clevis pin going through an opened out hole on a normal servo horn.

To make it secure lengthwise i drilled a 2mm hole in the IDS mono plastic mono pushrod and made an L bend in a metal 2mm pushrod and wound round with kevlar thread secured with thin cyano. 

I am very happy with this set up and i get full movement on crow brakes and ailerons also full movement with approx 90% servo travel so torque and resolution good. Plus it just feels better mechanically. I will be using this system on my Samba Prestiges no question

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I found the very thin airfoil really suited the 8mm Kingmax CLS0512W servos. In the tip panels a 10mm servo only just fits and it is a bit if a squeeze.

 I used balsa shims bonded between the servo mounts to the underside of bottom wing skins to add a great deal of rigidity to linkage. The wing skins on the Osprey are nice and hard (they are post cured at high temperature) and when you squeeze the leading edge D box the lamination is excellent with none of that sickly cracking sound you get when you squeeze some models but this Osprey is quite a light one and the skins do flex a bit around the servos when you apply force to the control surfaces. By bonding the servo frame to the opposing wing skin this flex was totally eliminated. The servorahmen frames make it very easy to do this as on the bearing end they have a molded shelf for this purpose

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