T31M build log

[Stephen Belshaw]

A little more progress to update. After a lot of checking, tweaking and double checking the 8swg cabanes were fastened to the formers using copper wire and soldered in place. I dry fitted them to the fuselage for yet more checks, more fettling and, as a final check, fitted the brass tubes and root ribs to confirm alignment and incidence:

 

 

 

The two formers were then epoxied in place, first to one side before joining the two together, followed by F1 after cutting a slot to allow for the battery. I've adopted the suggestion by EarlyBird which will enable the battery to drop in through a hatch, feeding it rearwards through F2 before pushing it forwards through F1 by the requisite amount. I think Peter designed this model for a .40cu which, I gather, weighs around 300g. My motor and LiPo combo come in at well over that, so I'm hopeful that will be enough to not need any nose weight:

 

 

 

 

Next job was to glue on the 1/64" ply sides using aliphatic and, after leaving overnight to dry, pull in the rear end adding the fin, top in-fill and underside balsa/ply support for the tailwheel assembly:

 

 

 

 

 

 

Finally, with the addition of the cross supports we have something that looks like a fuselage:

 

 

 

 

Edited December 9, 2021 by Stephen Belshaw

[Peter Miller]

That is looking really good.

 

At least with the long tail moment any weight needed to correct nose heaviness will be minimal. 

[Stephen Belshaw]

Quite a bit of bending, twisting, fettling and wastage of wire went in to forming the undercarriage, after which the binding and soldering was, in contrast, something to be enjoyed! A 100W iron and plenty of flux made for a quick and neat job, the whole was then epoxied in place. The eagle eyed amongst you will notice that the forward bottom sheeting has the grain running the wrong way:

 

 

 

 

I'd previously added 1/4" balsa doubles between F2 and F3 these were further reinforced with 1/4" gussets making for a very solid box around the undercarriage:

 

 

 

The rear upper deck formers were located using the stringer and pinned in place before glueing with Rocket Hot CA:

 

 

 

The battery tray was then epoxied in place and the forward formers were then dry fitted, additional formers were made up to create the battery hatch:

 

 

 

After building up the formers, adding the stringer and framework for the hatch the whole front end was sheeted using Super Phatic and being careful to leave the hatch area unglued:

 

 

 

 

 

Edited December 13, 2021 by Stephen Belshaw
Typo.

[Peter Miller]

A very nice job.

The grain of that front sheet is not really too important.

 

A good wire bender is a great help.

 

Very nice soldering too.

 

 

[Stephen Belshaw]

25 minutes ago, Peter Miller said:

A very nice job.

The grain of that front sheet is not really too important.

 

A good wire bender is a great help.

 

Very nice soldering too.

 

Thank you Peter. I have to say that, so far, it's been a really enjoyable build (wire hassles aside).

 

25 minutes ago, Peter Miller said:

 

 

[Jonathan M]

Proper job Stephen!

 

I also really like it when people insert spaces between their photos - makes the visuals much easier to read than continuous reels! ?

[Peter Miller]

I am glad that you are enjoying the build. I like to keep things simple usually.

[Stephen Belshaw]

It took me the best part of two days to figure out the design and make the removable cowl, I drew it up roughly on tracing paper over the plan, transferred it to balsa, cut it out and assembled it on the fly. The first effort was scrapped as the angles were not right, what looked ok in 2D didn't work in 3D:

 

 

 

Compared to what I was aiming for:

 

 

 

The whole cowl is to be removable, secured by two screws each side, fabricated from 1/8" sheet for the sides and underside with planking forming the top deck and a 1/4' front nosepiece.  I'll use 1/64" ply to simulate the panel overlaps and the whole will be covered in lightweight cloth and Eze-Kote before painting. Much happier with the basic shape of this one:

 

 

 

 

At some point I'll have to tackle the dummy air-cooled VW engine, I've not entirely worked out how I'm going to do this yet .............

 

 

 

 

 

[Peter Miller]

They are not hard to do.  You can find good drawings and pictures on the internet. 

[Basil]

Stephen, nice build.Your wire bender looks nice and sturdy, where did you get it?

Bas

[Stephen Belshaw]

28 minutes ago, Basil said:

Stephen, nice build.Your wire bender looks nice and sturdy, where did you get it?

Bas

Thank you Basil.

 

I got the wire bender from here https://www.lindinger.at convenient for me as I am in Hungary but I think it might be available in the UK under the K&S brand.

 

[Basil]

You are correct, called the 'Mighty bender'.  Similar from 4max but cheaper I believe. Many thanks.

Bas

[Peter Miller]

For your dummy engine.  Not sure if the scale is right but might be nearly right

http://www.vortex-vacforms.co.uk/radials.htm

 

It says radials but there are a couple of smaller flat fours

[Stephen Belshaw]

2 hours ago, Peter Miller said:

For your dummy engine.  Not sure if the scale is right but might be nearly right

http://www.vortex-vacforms.co.uk/radials.htm

 

It says radials but there are a couple of smaller flat fours

 

Interesting Peter, thank you. The only viable option would be the 1/5 scale RD11 flat four, my prototype G-BZLK appears to have a VW engine with the cylinders conjoined, it also has a lot of pipework!

 

My preferred option would be a 3D print file (I have a printer) but cannot locate one on "thingiverse" or elsewhere. Second option is the traditional balsa bashing route using string to simulate the fins but I'm not clear as yet how to go about modelling the exhaust. And with Vortex I now have a third option.

[Peter Miller]

When I did mine (over 30 years ago!!) I used laminations of thin ply and various thicknesses of balsa with a balsa rocker box.

 

Much more realistic than string.

 

I will see if I can find pictures.

[Peter Miller]

That didn't take long

[Peter Miller]

Sorry, down loaded un edited version

[kevin b]

Stephen.

Go to the Grab CAD community website   https://grabcad.com/

Create an account (It's free).

Log in and go to the library.

Type in the search box     VW Engine.

 

Enjoy !

[Stephen Belshaw]

Tidied the cowl up, added 1/64" ply sides and some "scale" air intakes, still a work in progress:

 

 

 

Added 1/64" ply undersides and sheeted the turtle deck leaving cutouts to route the servo cabling through:

 

 

 

 

Then it was on with the tail feathers, all built flat on the board from 5/16" balsa - quick and easy:

 

 

 

 

I deviated from the plan on the elevator, keeping a single leading edge strip rather than the two halves Peter designed but still utilising the wire joiner. Once this was glued up I removed some of the back of the leading edge in between the two tailplane halves and added a small chamfer so as to allow enough clearance for down elevator. On to this I epoxied a 1/32" ply plate. I then fabricated a brass and piano wire "paddle" which will locate in to a ball joint, this was then epoxied and screwed to the aforementioned ply plate:

 

 

 

Time then to dry fit it all together to ensure I have enough travel, the plan calls for max 1" elevator throws, I'd be surprised if I need that much but I have it if needs be:

 

 

 

 

 

 

 

[EarlyBird]

Interesting location for the elevator servo, which is giving me ideas for Rhapsody. ?

[GrumpyGnome]

Presumably to be mounted upside-down, to provide easier access for maintenance......

[Peter Miller]

I think Stephen may be using a bolt on tailplane.

[EarlyBird]

Fit the servo to the bottom of the tailplane and unplug for servicing?

[Stephen Belshaw]

Yes my tailplane will be removable, secured by two 4mm nylon bolts. The servo will be mounted on a ply plate and bonded to the inside left hand side of the fuselage so will be fully concealed but accessible by removing the tailplane. Rudder servo to be mounted under the cockpit and will be a closed loop run through snake outers.

[Peter Miller]

With the T31 the tailplane is in front of the fin so the servo could be screwed down to mounts in the fuselage.  The tailplane can then be unscrewed as shown on the plan to get at the servo.

 

I can't see this system working on Rhapsody as the fuselage/tail assembly is to complex to do the job neatly and easily