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Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 28 Oct 2019, 09:55
by Cliff Evans
Sorry Brian. Thought I had put the details in the fuss! Better late than never!

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 28 Oct 2019, 11:43
by Peter Balcombe
Sorry Brian,
I now recall that when I remodelled my Dart15 tail feathers, I took the original tailplane half planform & knocked up an equivalent with what looks like a solid front (covering both joiners) with a few rear riblets to simulate the full size open rear structure.
I never got around to putting the tailplane detail down on paper, so the built up plan only covered the wing.
Each tailplane half is 275mm long, Root chord approx. 125mm, tip chord approx. 97mm
The pic below gives an idea of the internal structure.
Peter

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 30 Oct 2019, 16:19
by B Sharp
Peter, Your tailplane construction looks almost identical to mine although the area of mine is fractionally less than yours. It looks as though "Great minds think alike". (We will now wait for the usual response to that last comment from any number of the usual people !)
Today has been spent doing "Life" things but I will get down to work soldering up the wiring harness after tea.
Brian. :D :D :D

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 03 Nov 2019, 14:21
by B Sharp
I now have two completed and covered wing halves. The wiring has been completed with Mpx plugs and sockets and the Mpx wing retainers have also been fitted in the wing roots.
The thin wing servos have been glued into the servo bays in the wings and the ailerons fitted and hinged with “Sylglas” tape. The aileron pushrods are so short that it proved a bit of a problem to make them adjustable. I usually fit two metal clevises back to back on a threaded rod however there was no room to do this on the dart. You will be able to see from the photos how I resolved the problem.
The fuselage is also nearing completion. All the radio gear is now in place with the exception of the battery and the wheel has been fitted. The battery will be fitted once I start balancing.
I am now fast approaching the point when I will have to assemble the component parts and work out the C of G. The default position will be just forward of the spar but I will use a CG calculator to find the range of settings that I want.
Brian. :)

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 03 Nov 2019, 14:50
by B Sharp
I have just done the CofG calks and they are very interesting (to me at any rate).
The set of drawings which Clive has recently sent me show the CofG at 57 mm back from the leading edge of the wing.
My first calculation with the static margin set at 15% (safe) has the CofG at 53mm back from the leading edge.
With the static margin re-set at 10% (which is where I will likely end up after a couple of trimming flights) the CofG comes in at 61mm from the leading edge. This gives the recommended 57mm a calculated static margin of 12.7% - not unreasonable at all under the circumstances.
It looks like I will add lead to the nose till I get 57mm then work backwards from there towards 61mm.
Brian. :D

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 03 Nov 2019, 15:53
by Peter Balcombe
All looks very nice Brian :)
I look forward to hearing of the successful maiden flight.

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 03 Nov 2019, 17:30
by B Sharp
Thanks Peter. However, the way the weather is shaping up at the moment it may be some time before I get the Dart in the air.
Brian :)

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 05 Nov 2019, 14:30
by B Sharp
Well the Dart 17 build is now officially over.
After a moulded lump of lead weighing 570gm was added to the nose the final weight of the model came in at 2.86kg (6lb 4oz in old money). This gave a wing loading of 18oz/ft2. I am quietly pleased with this weight and loading as it will be easy to carry up my local hill and should have a reasonable light wind performance.
I have attached a pile of photos to this post showing the fully assembled model. The photo of the tail end shows the much modified fin and rudder which I think justifies the effort involved as it looks just right to me. I was a little worried that the centre section/wing joint area would look a little strange but the photo from above shows that I managed to achieve the classic Dart outline.
The only thing left to do is fly the model. I would ideally like a 8mph to 12mph West to South-westerly with no rain and not too cold. When I do manage the maiden and if I get some photo I will post them in the “Who’s building what for” thread.
A Very Happy and Contented Brian. :D :D :D :D :D

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 05 Nov 2019, 14:33
by Cliff Evans
Well done Brian, looks great and, I am sure she will fly as well as she looks.

Re: 1/5 Scale Slingsby T51 Dart 17.

Posted: 05 Nov 2019, 15:59
by Peter Balcombe
Very nice Brian :)
I’m sure that it will fly very nicely.