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T31M build log


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A slight change of plan on the elevator servo, I couldn't get it installed on one side of the fuselage as intended and at the same time leave enough room to route the snake inners that will take the closed loop steel cable. Instead I fabricated a 1/16" ply plate to place the servo centrally and leave  just enough room either side for the snake inners:

 

IMG_1385.thumb.jpeg.f3d85283dff17e1208540bf6b4cd0ce3.jpeg

 

 

Servo in place with the ball joint visible that couples with the peg on the elevator:

 

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From below showing how snug it is:

 

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And from the side:

 

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Rudder and elevator hinged with Robart style hinges, fibreglass control horn bonded in to the rudder, so that about clears up the back end:

 

IMG_1390.thumb.jpeg.2a94f63545f2ff595d357c8be8627b27.jpeg

 

 

 

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Forming the coaming over the rear turtle deck and routing the  wing cables that will feed both ailerons and airbrakes:

 

IMG_1392.thumb.jpeg.a4cd151d32df98801ad354a5d8fb6295.jpeg

 

 

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A little more work on the cowling, gradually taking shape:

 

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And, thanks to the tip off from Kevin b, I sourced a file for the VW aero engine on GrabCad which I can print on my Anycubic Vyper. This is the second attempt which will be refined for the "production" version. I still need to figure out how to do the Heath Robinson exhaust system:

 

IMG_1397.thumb.jpeg.a82731ba2697e6087e1119e69cea1351.jpeg

 

 

 

Tail feathers completed and covered in very old stock silver Solar-film and HobbyKing Carmine Red. They can be tucked away now, safe from hangar rash:

 

IMG_1395.thumb.jpeg.ed79a142c6d532e2ad4dbc32e62f5ec7.jpeg

 

 

Building a joiner box to carry the wiring and wing fixings, I'm deviating from the plans which utilise small screws and rubber bands to retain the wings, instead I'm proposing to use mini click-fix nylon wing retainers (one per wing) which will be fixed at max wing thickness position:

 

IMG_1398.thumb.jpeg.f8d4bed359e18747a616e255417c6a49.jpeg

 

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Now moving on to the wings.

 

Peter suggests laying down the lower cap strips and sheeting, then bonding the spars to them, followed by the ribs and then the trailing edge and so on. I've never built a wing this way before, it seems the TE is notched to accept the ribs but the ribs are shaped to a fine point and would be the wrong angle as they flow in to the TE. Unless I'm misinterpreting something, perhaps Peter could shed some light on this for me?

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Had another look at this and did a dry fit with everything in it's correct place, seems I made a schoolboy error or suffered a senior moment by neglecting to factor in the cap strips! Stand easy chaps!

 

I can see I'm going to have to be super accurate notching out the trailing edge ..........

Edited by Stephen Belshaw
Typo.
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Moving on to the wings, I thought this was going to be quite time consuming but, batch producing the cap strips, scarfe joining the spruce spars and leaving overnight for the aliphatic to set, plus everything else being laser cut, put me in position to crack on with what turned out to be a fairly quick process:

 

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I came across one small snag, the half ribs around the aileron area were all too short, maybe a mismatch between the plan and the laser cutting files:

 

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A bit of scrap infill will quickly sort that and will be buttressed by the 1/4" sheet trailing edge, using a combination of Superphatic and CA the first wing was soon done in its basic form and quickly followed by the second:

 

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Whilst all this was going off I had the 3D printer running and in between balsa bashing sessions let loose on my artistic side in order to furnish the T31M with a pilot:

 

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On 29/12/2021 at 14:54, Stephen Belshaw said:

Forming the coaming over the rear turtle deck and routing the  wing cables that will feed both ailerons and airbrakes:

 

IMG_1392.thumb.jpeg.a4cd151d32df98801ad354a5d8fb6295.jpeg

 

 

IMG_1393.thumb.jpeg.f9e01d9e5958d0d96d0831e087814e37.jpeg

 

 

A little more work on the cowling, gradually taking shape:

 

IMG_1394.thumb.jpeg.75d1e0e60ded135318446f732d8302c7.jpeg

 

 

And, thanks to the tip off from Kevin b, I sourced a file for the VW aero engine on GrabCad which I can print on my Anycubic Vyper. This is the second attempt which will be refined for the "production" version. I still need to figure out how to do the Heath Robinson exhaust system:

 

IMG_1397.thumb.jpeg.a82731ba2697e6087e1119e69cea1351.jpeg

 

 

 

Tail feathers completed and covered in very old stock silver Solar-film and HobbyKing Carmine Red. They can be tucked away now, safe from hangar rash:

 

IMG_1395.thumb.jpeg.ed79a142c6d532e2ad4dbc32e62f5ec7.jpeg

 

 

Building a joiner box to carry the wiring and wing fixings, I'm deviating from the plans which utilise small screws and rubber bands to retain the wings, instead I'm proposing to use mini click-fix nylon wing retainers (one per wing) which will be fixed at max wing thickness position:

 

IMG_1398.thumb.jpeg.f8d4bed359e18747a616e255417c6a49.jpeg

 

Stephen where do I get the minifix click wing fixings. I cant find them anywhere, please

Bas

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Bas, these are what I bought https://www.lindinger.at/en/Building-Accessories-More/Catalogues-Promotional-Items/TOPMODEL-CLIP-FIXING-MINI-ARRANGEMENT-2-PAIRS-FOR-WING-MOUNTING/9708832

 

As I mentioned before I am in Hungary so that supplier is convenient for me, they will ship to the UK I think if you cannot find them locally.

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Stephen, cant quite fathom out how they work. I assume that the hollow screw fits in the wing, the long screw base /split end fit in the fuzz and the split end pushes in the hollow section in the wing. So it's the shoulders on the split end that do the holding. Use the wedge to just lever the wing off.!!! dont the shoulders wear down in time?

Bas

Edited by Basil
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15 hours ago, Basil said:

Stephen, cant quite fathom out how they work. I assume that the hollow screw fits in the wing, the long screw base /split end fit in the fuzz and the split end pushes in the hollow section in the wing. So it's the shoulders on the split end that do the holding. Use the wedge to just lever the wing off.!!! dont the shoulders wear down in time?

Bas

Although I've had similar on previous models I've never actually used this specific type before, the T31M will be the first, but my understanding is that the long bit goes in the wing and the shorter female end goes in the fus. Previous ones I had were retained by a circular spring, like a mini keyring, but these are friction fit and I have heard that they can be a bit of a fight to "unclip", they will also need very accurate alignment to function well. I'm not to far off from fitting them so we'll see ................ 

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Quick question for Peter. 

 

The plan shows webbing only on the front face of the front spars, coming from a glider background I'm used to taking them all the way out to the wingtip. No webs on the reverse to form an enclosed box around the brass wing joiner tubes and nothing at all on the rear spars. I'm assuming that the struts do the work the webbing would otherwise have done and that I have correctly interpreted the plan?

 

IMG_1420.thumb.jpeg.cb469da60bc727e29f826bc904fb4366.jpeg

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My standard wing structure for aerobatic models is leading edge sheet back to the spar and just webs all along the front face of the spare.

However I can't really remember on this model. IT does look as if I did not use webs beyond the brass tube.  It also looks as if I didn't use webs on the rear spar but I would have filled in between the spars with balsa round the tubes.

 If you want to add webs all down the spar please feel free to do so.

 

I have to admit that when I look at another person's plan I quite often say "I wouldn't have done it that way!" and so I have absolutely no objection to people building for my plans to say the same thing.

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Thanks for the reply Peter. I'm building this closely following your instructions from the RCM&E February 2010 edition, using it as a learning curve for building something other than my normal gliders so will stick with it as is I think. I now have the leading edge on and the wing panel feels strong enough and also very light so, not looking for extra work or adding weight I'll carry on as per the plan.

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Wing building continues. Top sheeting added, leading edge and top cap strips. Trailing edges notched out with three hacksaw blades taped together, quick, easy and accurate leaving just enough wood to fine tune with a file:

 

IMG_1419.thumb.jpeg.53b1e765ef107bda2ea211fb12896de9.jpeg

 

 

Wing tips built using the supplied laser cut flat sheet and scrap, ailerons finished and roughly shaped:

 

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Airbrakes made from laminations of 1/32" ply and 1/16" balsa, simple sheeting surround:

 

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Leaving me with a pair of basic wing structures needing servo installation, wing joiner tubes, root area top sheeting and sanding:

 

IMG_1424.thumb.jpeg.16666efb8e4325330353234490e5fcd6.jpeg

 

 

 

 

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Lying in bed in the early hours thinking, I wondered if you might be interested in building my Easter Eagle Senior.

 

This powered glider is big. 82" span but with a very low aspect ratio wing.  The result is a glider with amazing performance.  I sold mine to a friend who uses it with a compact Canon camera.  He flies at Minchinghampton Common and is always amused when the local glider fliers turn up...try and fly,then say "No lift today"  and go home while his Easter Eagle is staying up for an hour on a 2200 Mah battery.

 

My Easter Eagles have proved my theory about low aspect ratio gliders over a long time but the best proof came at a huge Vintage Glider Rally a few years ago at Tibbenham.

 

There it was a perfect day, calm, warm and sunny. Gathered at the rally where all the great names is high performance gliders from the past, Minimoas, Rhonsperbers etc.  About midday a huge thermal came through and everyone scramble to get airborne.It was a wonderful sight to see at least 20 great sailplanes going up in the lift.

 

What really made my day with the proof of my theory because right at the very top and going up faster than all the others was a Slingsby Sedbergh.. Yes, the good old "Barge"!

 

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Two Easter Eagles in formation. I seem to remember that the smaller one was the 55" span version

 

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A shot of my village taken from the EE Sr from over a mile away. The arrow is pointing at my house.

 

I am not sure if the EE Sr plans are available from Sarik. Must check but I have PDFs if they are not

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The one at Sarik is my original 55" one from many years ago. They don't list the Senior one so if you care to PM me you email address I can send you the PDFs.

 

You can easily change the tail  design. I like the V tail as it protects it against landing in rough ground but I don't mind people  changing things to suit their own preferences

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