Scale Soaring UK

This is another in my OAP-Friendly range of designs, and I expect to be able to self-launch without too much difficulty when normality returns to the throne...
The fuselage and empennage are all newly drawn, but I've retained the Compufoil files from my last 3.5 scale version. As this was to be E-assisted, the wing chord was extended by 5%, and as it flies so nicely, I've retained this wing for the new version...
The fuselage is assembled by the usual half-shell method...

With the planking and diagonals applied in sufficient quantity, the half-shell can be removed from the board....

If you don't slow down, that will be ready to fly soon...



BC

Barry_Cole wrote: ↑15 Feb 2021, 13:12 If you don't slow down, that will be ready to fly soon...



BC

lol

C'mon, Barry, you've already aerotowed this one...do try to keep up!

It became obvious at this early stage, that fitting the chosen retract was going to be a tricky business...

Meanwhile, the building up of the fuselage continues...

Continuing with the fuselage: The u/c doors are from two pieces of .8mm ply laminated together to follow the curve of the fuselage

The retract of choice was the Topmodel 099ELRS 1/4 scale electric retract. This has the advantage that the inbuilt motor leaves space either side of the frame for the rudder and elevator servos inside a fuselage with notoriously restricted space. The disadvantage is that instead of the conventional prongs fore and aft, this one is designed to be screwed in from underneath. As it turned out the edges of the mounting plate could be used in a conventional fashion with a bit of j-j-j-jiggling about, Granville. When the job was done, I suffered from a touch of builder's remorse in that maybe the the rear former could have been placed more conveniently. If anyone has a go at this design, I would recommend getting the retract first before building commences... (At this stage, Motley's version was similarly completed)

Moving on now to the AMT...

Followed by the AMT...

Now the rear end can be brought nearer to a conclusion...

Moving on now to the canopy frame...

Now for the wings...The Dart has two brass joiner boxes in the wing, one 16mm & one 13mm: each one sits under one set of the 5mm spars. It's always a good idea when epoxying in the second joiner to insert the blades and check that they are absolutely parallel...

Hi Chris, is the ply sheeting on the rear fuselage 1/64 or 1/32? I ask as I would have assumed 1/32 but it looks more like 1/64 to me from the colour in the photos.

No Andrew, that's 0.6mm, or 1/48th ply...

Ok, thanks, .6mm is a size I hadn't come across. I'm enjoying seeing this come together.

You can get 0.6 from SlecUK.

With the lower sheeting added, the wing can be laid on its jigging supports and the top sheeting glued in place....

Thanks Cliff, I've just had a delivery from SLEC too!

Now the wing roots can finalised and faced with 0.8mm ply...

A quick rig to boost enthusiasm, then on to fitting the wings to the fuselage...

With all the usual alignment tasks completed, the fairings can be infilled with balsa (scrap TE profiles are sometimes excellent for this) and the wings blended to the fuselage with the standard application of polyester filler.... Note that the scale cut-out of the wing TE at the root has been abandoned in favour of a simple straight edge junction to avoid the collateral damage the sticky-out bits can cause in transport. (This issue will be faked in the finishing stage)

The ailerons are relatively simple, and built flat to the board. The TE at the wing tip is made of blanks of 12mm balsa, shaped to the chord...
The airbrake servo is a tight fit, but is removable... (The servo cost £1.90)

Now for the canopy: this is held in place with three 8mm magnets front and rear. The instrument binnacle is attached to the canopy to give good access to the fuselage for fitting and removing the LiPo...

I seem to have lost the pics for the airbrakes, so I've substituted the ones from the current project which are near enough identical... Note that in extremis, the whole assembly can be removed if necessary at any stage.

Chris, I have a question.

When you build the wing it is framed up flat on the board, lower sheeting added and at this point the wing is still quite flexible. You then jig it up to add the top sheet which locks in any washout, I presume there is washout? You then build the aileron flat and match the wing tip to the tip of the aileron but what happens to the washout? I am trying to visualise it with difficulty. I am used to building the ailerons as part of the wing and then separating them which can be fiddly.

I have always built airbrakes with the arms boxed in so that the pivot is supported at both the front and rear of the airbrake arms, you seem to use a screw through the arms so that the airbrakes can be removed if necessary. I presume has been trouble free?

Andrew,
I suspect that in common with most of the CW designs over the past few years, Chris has used an HQ section - so no need for any washout to be built in.
No doubt CW will confirm or otherwise
Peter

That's right, it's been two or three decades since I built a wing with any washout...

The airbrakes are a cast iron son-of-a-female dog to get to close properly, but once they do I've never had to re-visit them. (There: I've been and gone and said it now!)

Okay, thanks. In all my years of building models I am still learning and I would never have considered building a model without washout and I now appreciate that the wing section used doesn't need it.

I hope I haven't jinxed the airbrake by asking

The finish process is my usual one these days...Solartex and 2K paint on the fuselage, and film on the flying surfaces.

Specs:
SCALE: 1/4
SPAN: 4.25m
A.U.W. 14lbs (6.35Kgs)
Wing Section: HQ3514-3512

Motley's version is also complete and awaits its maiden...

Looks fabulous!

Thank you, Paul... The maiden flight went without a hitch, and for the first time, nothing needed post-flight adjustment. This could be due to accumulated experience, or just sheer luck! (You're right: definitely the latter) It's a lovely model to fly, even if I would say that, wouldn't I?
Hopefully, next month we will be able get some more action pics and video...

Lovely job as usual. Will plans be available Chris or are they already?

Photo please Chris.

Stunning build!

Not a fully annotated plan, Andrew, more of a working drawing, but all the info you need will be there, plus, if you want to cut out your own parts, PDF's in A4 format. c_williams30@sky.com

Thanks Chris. The Dart 17 has always been a favourite of mine.

Update: The Darts' 1st slope appearance...

They look great Chris.

Thanks, Cliff... we're lucky to get any pics at all with the weather being served up lately!

Finally...le video