1/4 Scale Tiger Moth build, a work very much in progress

[RottenRow]

Thank you Richard for all of the information and photos.

 

I will make a note of it all for when I need to make a pair of the spreader bars.

 

I made some previously for a smaller (1/6 scale) Tiger Moth but they were simply 1/8” dowel with fine radial cuts into which the (non-functional) rigging wires were a tight fit. They looked ok but yours are much more scale.

 

Brian.

[Richard Thornton 2]

22 minutes ago, RottenRow said:

Thank you Richard for all of the information and photos.

 

I will make a note of it all for when I need to make a pair of the spreader bars.

 

I made some previously for a smaller (1/6 scale) Tiger Moth but they were simply 1/8” dowel with fine radial cuts into which the (non-functional) rigging wires were a tight fit. They looked ok but yours are much more scale.

 

Brian.

Absolute please Brian.

My inspiration came from the owner of G-ERDS who has over the years shared some fantastic stories about the aircraft, its travels and his enthusiasm and input has made my build flow a lot better. 1/4 scale is large enough or should that be small enough to model as per the full size and as silly as it sounds, the way it was originally designed and built is often the easiest and safest way of building.

My model is from the Traplet plan and I think it can be classified as ‘semi scale’ without upsetting anyone. The scale bits that I have added have been as a result of climbing all over G-ERDS and logging all the things that make this aircraft unique and my model a copy of it.

 

[Richard Thornton 2]

Todays little project.

This might stop me poking my eye out too. It’s the remove before flight tab which on this aircraft is triangular shaped and not straight like others I have seen. All I need to do now is leave it in the sun to fade as it’s a bit ‘new’ looking.

Also need to add the piece of cotton as a tie back.

 

 

[Richard Thornton 2]

Now for a tricky bit.

I spent a lot of time reading the build log from PeterFs with regard to making the aileron drive boxes. Please see PeterF’s thread as it’s fantastic. The draw back from this system was that the cable around the drum gets crimped down and as Peter explains, splintered. I was worried about this actually happening later on when in use as could the wire cables work harden in use, splinter and then break in a place that once fitted would be a nightmare to replace, if it didn’t happen in flight!

I eventually found a tread to a 1/4 scale or 1/6 scale motorbike replacement chain by Tamiya and it actually has a rear wheel replacement sprocket too.

So using Peters assembly and adding the sprocket and chain, it’s done away with the worry of the drive wires breaking.

Resolving one issue created another.

There is an issue with how to keep the chain tight when the wings are not mounted on the fuselage. I resolved this by adding an adjustable linkage between the chain and the drive cables.

Photos to follow, and thanks to Manish for helping with the link to PeterF blog.

[Richard Thornton 2]

 

 

[Richard Thornton 2]

[Richard Thornton 2]

The finished assembly.

By adding the removable drive box covers means I can get access to anything within that needs a tweek or tightening up.
 

[Manish Chandrayan]

Hello Richard, could you please provide some more detail on how you ensure that the chain does not slip off the sprocket when the wings are taken off the fuselage? 

[Richard Thornton 2]

Good question Manish.

Pictures say 1000 words so attached is the drawing showing the setup and desired movement/throw of the control horn in relation to the disc movement.

The chain is looped around the sprocket, which has super pointed teeth allowing good penitration through the links. I guess as it’s intended location was a motorbike bouncing around at great speed, the chain must be ‘encouraged’ to stay on.

Stainless steel wire was then crimped onto each leg and both of legs were attached to a tiny bottle screw.

The bottle screws are attached to a link arm and once attached, all tightened up to keep tension in the chain at all times.

At the link arm, 2 sets of turnbuckles or bottle screws are fitted. They share the M2 nut and bolt, as one is fitted to the top half and the other to the bottom. The nuts are nyloc to allow a tiny bit of play which allows eye of the bottle screws to rotate.

The drawing only shows one inboard bottle screw, but there is one fitted to both sides.

 

[Richard Thornton 2]

This is the inboard hatch.

The chain can be seen attached to the wire and bottle screw.

The aluminium angle is there to prevent the spar bending and breaking as it now has 2 holes cut in it.

The brass nuts hold the arm in place which can be seen in the next photo.
 

The photo below shows the link arm, and the two longer bottle screws or turnbuckles in the second hatch.

These I made longer as there is more room to get my chubby fingers in when they need adjusting and tying back when correctly tensioned.

 

 

 

[Richard Thornton 2]

And this is the whole assembly from the underside.

Warning: It’s isn’t easy as everything is so small and fiddly. 
If you are going to make something like this, you need to dry run everything as I managed to put bits in, then found other bits had to go first, as the couldn’t be tightened or reached.

I haven’t lost my hair yet, but I have gone a fine hade of silver grey and my engineering vocabulary has improved 100 fold

 

[Manish Chandrayan]

Thanks for the detailed explanation Richard. Your drawings, pictures and explanations confirmed what I had been guessing. The cables from the chain fixed to the intermediate crank retain tension and thus the chain remains on sprocket when the wings are dismantled. 

Hope you have or are planning to safety wire all four of the turnbuckles. 

[Richard Thornton 2]

1 hour ago, Manish Chandrayan said:

Thanks for the detailed explanation Richard. Your drawings, pictures and explanations confirmed what I had been guessing. The cables from the chain fixed to the intermediate crank retain tension and thus the chain remains on sprocket when the wings are dismantled. 

Hope you have or are planning to safety wire all four of the turnbuckles. 

Yes, the innermost ones 2 each side have had safety wires wrapped around them to stop them unwinding, the outer 2 will be sorted and tied back when the links to the central servo have been complete.

I am using PeterF’s idea again here, with the ‘drive’ action being a ‘pulling’ motion on the aileron wire one side, whilst the opposite side side is moved by the central arm.

[PeterF]

Richard, hat off to you on this, I did think about going the chain route because that mimics the full size but could not find the parts. I am a little embarrassed now at not having worked through to this detail. I ended up with a wire breaking on the ground and swapping to low profile servos in the wings. Still flying the plane, last out a week ago and it still flies well and looks good.

[Richard Thornton 2]

Hi Peter.
Thanks for the compliment. I was really concerned about the wires work hardening a specially as they are stainless although very soft at going around corners.

My thanks to you for the detail of the fibre board brackets as that’s exactly where I started with mine but just happened to find the link chain.

 

This is similar to what I used and it was long enough to cut in 2, one length for each side

 

[Richard Thornton 2]

1 hour ago, PeterF said:

Richard, hat off to you on this, I did think about going the chain route because that mimics the full size but could not find the parts. I am a little embarrassed now at not having worked through to this detail. I ended up with a wire breaking on the ground and swapping to low profile servos in the wings. Still flying the plane, last out a week ago and it still flies well and looks good.

Really pleased to hear the model is still flying, I can’t believe how ‘big’ mine has grown since the wings have been covered. Hope it still fits into the back of my Mini.

[Richard Thornton 2]

Great couple of hours spent at Newark Air Museum recently.
This Tiger Moth G-MAZY is absolutely fantastic for the scale modeller.

The starboard side is covered as per flying aircraft whilst the port side is uncovered which allows you to see all the workings. 
This was a great help for wing fixings, slat operation, aileron drive box and cockpit layout as you can see where everything goes.

[Richard Thornton 2]

This is the next project.

The slat pulleys and tensioners.

I have already made up my mind that these would have been a seriously fiddly job to assemble each time the wings are attached and detached. With that in mind the wires into the wing roots have already been fitted and are spring loaded simply to apply some tension.

Again following PeterF build, he has some detail on the size and shape of the bracket fitted to the starboard side rear tank/wing brace.

I have spoken to the Owner of G-ERDS and he has explained that the wire cable passes through the fuselage, around a single sheave and is directed to the rear cockpit. There is another sheave in the system adjacent to the forward cockpit seat.

For the life of me I could not work out how this cabling went from the vertical, to the horizontal without going through 2 sheaves and that seemed like and impossible (oops we don’t use that word in modelling……) challenging issue to overcome.

I tuns out that the sheave is hidden behind the frame in the cockpit and only the bolt holding the thing in place is visible. The lead of the wire must be correct to keep it outside the cockpit until it meets the skin just under the strut support.

Everything is so much easier when you know how!

Edited June 8 by Richard Thornton 2
Photo didn’t upload

[Richard Thornton 2]

Photo showing the position of the cable passing through fuselage skin.

[Richard Thornton 2]

Got sidetracked this afternoon.

Fuel valve entry cover patch with stitching.

But this has raised an issue. I noticed that the fuel line is routed differently on this aircraft not like the aircraft that I was originally modelling. Also it doesn’t have rear view mirror, damn. I now have a spare rearview mirror that I really enjoyed making albeit years ago.

Another difference, there is pipework carrying the electric cables to the navigation lights on the port side, on the starboard side there is a fuel line from the extra tank via the hand pump in the rear cockpit.

Some 3.2mm or something like aluminium tube required me thinks.

Also, the strut pipe holders are fwd facing not aft.

 

 

 

[Ron Gray]

The trouble is it’s now getting difficult to see the difference between model and full size, so we’ll done Richard and keep at it.

[Murat Kece 1]

I thought they were from the real plane.. Amazing.. Excellent work.

[Richard Thornton 2]

21 hours ago, Ron Gray said:

The trouble is it’s now getting difficult to see the difference between model and full size, so well done Richard and keep at it.

Many thanks Ron and Murat Kese 1

Edited June 10 by Richard Thornton 2

[Richard Thornton 2]

More distractions. The weather is too cold to paint…… summer they say is here!

So the front cowl or ‘turtle deck’ ? needs finishing off.

The head cockpit head protectors are brown leather and have a distinctive fold and tacks to complete.

I tried a several options but they simply looked lumpy.

What I have finally come up with is a piece of black shrink sleeve which I put in the vice overnight to flatten.

Drilled some holes as per the full sized position and used some small rivets, the sort that hold machine signs down, and pushed them through.

Now to paint the final assembly to finish it off.

Fingers crossed.

[Ron Gray]

Can’t see the folds / creases in yours Richard 😉