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FX707S Albatross - 1.2m foam chuck glider RC conversions

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As I really don't like that big "V" slot (on my first not flapped FX707 I filled it in) I decided to go ahead and built a bigger, longer Depron flap using 2mm skin top and bottom.

At the same time I printed the tailing edge extensions for the aileron and the short bits that go on the rest of the  edge

A comparison of the original & extended wings.


It is the underside that shows the biggest difference.


Of course the aileron will have to have a "V" slot added but as the ailerons will have differential movement the slot will be less pronounced.

As I commented on the conversion of my first FX707 I doubt any of the changes will make a significant difference to the performance unless I do a conversion without any wing modifications and that I am not going to do.

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Not much progress but I have excavated out the inside of the cockpit canopy.


As supplied it weighed 5.2g. It now weighs 2.6g.

I am sure a 2.6g saving on what is likely to be a 360g plane will make no difference at all but its the principle of a 50% reduction that counts.

The extra space it creates inside the cockpit might come in handy too.   

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Still waiting for the servos so I decided to install the one that I have as a flap servo. Fortunately is the same as those I have ordered.

The installation is a bit unusual as what I am using as a flap was originally intended as an aileron so the servo cut outs are 'handed' which of course is no use for flaps and the cut outs were intend for top hinge/lower link. My flaps are bottom hinged with a top link so the cut out was going to need some modification anyway. Stared with the LH wing as this was likely to need less modification to get the linkage in the right place.

The underside with the servo in place.


Servo cut out is not quite deep enough for a 3.7g servo but I did not fancy trying to make it any deeper. The servo is glued in with POR all round so it adds a bit to the stiffness of the wing.

The top surface.


A video of the flap in operation.


It took a bit of trial and error to get both the flap horn geometry and the link to give the correct movement whilst retaining full servo travel.

At least I now know what is required to be done when the servos arrive. 


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After much dithering I have decided to keep the same type of motor on the flapped FX707. I have ordered a slightly larger prop as even the 5.3x3.3 was only drawing 7.5 amps on a 3s.

This decision means I could use the existing printed motor mount and cowling. However I never particularly liked the cowling side air exits so I will try bulkhead holes to exhaust the motor cooling air into the cockpit and thence to a low pressure region further down the fuselage.

The top inlet cowling with no side exits.


The motor mounting has two large holes in it.


These holes will be matched in the nose foam that supports the motor mount.

Well that's the plan.  🙂      

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Boy has this been slow going!

At last the  4 wing servos are in and connected up so the wing can be permanently joined.

This allows the wing to be test fitted on the fuselage.


The underside showing the servos and their wires buried into wing.


Even so there is quite a bit to do. In theory it is just a repeat of what I did on the first FX707 but it tends not to work out quite like that!

Next is the tricky job of cutting the nose off at the right place and angle to install the printed motor mount.

Given that the weight of the 4 wing servos act at about the same point as the previous 2 and everything in the fuselage should be the same the CoG of the flapped XF707 should end up about the same point.

We shall see.  

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The cowling and motor with the printed mount glued onto the cut off nose.


The ducts matching the holes in the motor mount exit into the cockpit.


This layout ensures the air from the nose inlet will travel across the motor, hopefully. Just as well it is only a 100W motor!

The "exits to air" will be added further down the fuselage.

ESC next, likely to bed semi recessed externally as in my first FX707. 

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Now more or less complete and with such rotten weather I painted the control surfaces.


I am still waiting for its 5,3 x 3.3 prop. If necessary it could be flown with the 5x3 fitted. The current weather forecast suggests it could be some time before it can have its maiden.

A short video of a full control test.


With an 850 mAh 3s LiPo it weighs 332g. Which is just 50g more than it did as a chuck glider out of the box. 

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