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Peterf's 1/4 scale Falcon Models Tiger Moth

Build log for my quarter scale Tiger Moth

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PeterF14/04/2018 21:20:54
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318 forum posts
545 photos

Here is the drawing I used for the luggage catches, the dimension stated as 5mm, I actually made them closer to 6mm.

my luggage catches.jpg

PeterF17/04/2018 22:18:02
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318 forum posts
545 photos

The last few days have seen more scale detail added, namely the air speed indicator (ASI), the slot control cabling and the clips between the double rudder wires. This has been split over two posts because of forum limitations. Most of this has used the same 0.5mm aluminium sheet I have used for much of the other detail and some items turned on the lathe.

The ASI is based on some drawings Manish put on his build log for the DH60 model. The main difference I noted when I started was that the Tiger Moth I am building had less pronounced radii at the corners, so I took account of that. I printed the drawings off at reduced scale until I had them the right size. Glued them to the aluminium sheet with double sided tape and cut them out. I cut the slot in the angled plate by putting it in the milling attachment on the lathe and running a 1.5mm end mill along the plate, much better finish to the slot than doing it by hand. The speed scale was drawn up in PowerPoint and then printed out on inkjet vinyl, cut out and glued in place. The file is attached. The wire was from 0.9mm piano wire suitable bent around a former of the right diameter.

The straps to mount it to the interplane strut are cut from the aluminium sheet and backed with 0.4mm rubber per the full scale. A trick I developed to cut long strips of rubber accurately was to put a piece of masking tape on one side of the rubber, then hold it down with a steel ruler and cut strips off with a sharp scalpel. No worries about floppy rubber stretching and cutting with a jagged edge. The rubber was glued to the aluminium with UHU Por before bending to shape. These are clamped onto the struts with 10BA bolts, entirely functional.

It was when I came to attach the straps to the ASI that I realised I had missed the other key differnece between DH60 and DH82, namely thee struts are not vertical, so the lower mounting hole was in the wrong place. To late to change so I drilled another hole and filled the wrong one a bit, I was not going to make a whole new ASI. Some of the full scale ASI was attached together with rivets, so I made up some 1.2mm dia aluminium flat head rivets from 3mm rod in the lathe. Another difference is the Moth I am building only has one bolt in the plate that is attached to the spring, the drawing has two.

DH60 ASI drawing. Note if used on DH82, relocate lower mounting hole at an angle and leave off lower hole on deflection plate.dh60 asi.jpg

Printed scale in MPHasi scale.jpg

Parts after being cut out and drilled / slot milleddsc06260.jpg

ASI completed, note the filled hole and new hole.dsc06279.jpg

Rubber strips cut with masking tape to hole shape and glued onto aluminium stripdsc06275.jpg

ASI mounting straps made updsc06281.jpg

ASI plus mounting strapsdsc06282.jpg

ASI mounteddsc06291.jpg

ASI mounteddsc06294.jpg

PeterF17/04/2018 22:21:08
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318 forum posts
545 photos

The plane I am modelling still has the slots and slot control cable installed, hence I wanted to replicate the cabling around the cabane. There were a few straps to attach wire guides, made up as the other straps. At the top of the cabane strut there is a pulley assembly where the cable direction changes through 90 degree. The pulleys were made from bar turned on the lathe and the mounting bracket dimensions worked out from photographs and cut from 0.5mm aluminium plate, it is reasonably authentic. I have attached my patterns if someone else wants to use them. The turnbuckle is from Mick Reeves Models, it is probably slightly over scale in length. The one thing I have added is a small bracket to hole the left hand wire in place when the wing is not there, otherwise the wire and turnbuckle would flop about. I will add holes on the ends of the wings with mock leather covers. When the wings are attached, the ends of the cable will pass into the wings.

The clips between the double rudder wires were a piece of cake in comparison to the above 2 items, being simply 0.5mm aluminium sheet with the ends rolled over.

Slot control cable pulleys support bracket drawingsslot pulley brackets.jpg

Slot control cable pulleysdsc06313.jpg

control cable pulleys mounted to their support bracketdsc06316.jpg

Pulley unit mounted to the top of the cabane strutdsc06318.jpg

Completed slot control cablingdsc06323.jpg

Clips between double rudder wires, there is another (unseen) one at the side of the cockpitsdsc06297.jpg

Close up of the clip, 0.5mm aluminium sheet with rolled over endsdsc06307.jpg

Edited By PeterF on 17/04/2018 22:31:29

PeterF25/04/2018 14:31:22
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318 forum posts
545 photos

I have completed all the scale fittings on the fuel tank. These are representative details, they may not be mm perfect. There is the level gauge, vent, link pipe under the front cabane bar, the drain valve, main fuel valve complete with actuation rods and the pipe to the engine. The compression fittings were turned from hex brass, the valves from aluminium and the actuation rods were piano wire with clevises turned / milled from aluminium. The level gauge is made from the scrap box contents, the metal tube is a section on an old 35MHz transmitter aerial, the sight glass is from a tube that some brass came in. I milled the obround slot in the thin wall tube whilst I had a piece of dowel inside the tube so that it did not collapse or tear.

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Manish Chandrayan25/04/2018 14:56:02
397 forum posts
56 photos

They may not be mm perfect but they absolutely look the part . yes

And now for the question smile p

What dia is the fuel gauge tube?

Once again fantastic tip,that dowel inside tube while cuttingyes

Danny Fenton25/04/2018 15:06:53
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8461 forum posts
3434 photos

Really looks ace, well done

cymaz25/04/2018 17:00:56
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7536 forum posts
975 photos

A masterclass, truly a class actyes

PeterF25/04/2018 18:05:54
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318 forum posts
545 photos

The aerial tube is 8.85mm OD and the plastic tube is 8.05mm OD. I was originally going to use 8.0mm OD aerial tube but when I found the plastic tube in the scraps box it was too good to be true, so I went up on the metal tube one size. If I had stayed with the smaller metal tube I would have had to make the sight glass from rolled sheet.

Manish Chandrayan25/04/2018 18:15:52
397 forum posts
56 photos
Thank you. I should have 8 mm tube or will scrounge around for an old Tx ariel
PeterF28/04/2018 22:14:18
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318 forum posts
545 photos

Another update split over 2 posts due to limitations on the size / content of a post.

I have added three additional scale details, the exhaust, a small wind driven generator and the pitot tubes.

The exhaust is simply a piece of ABS tube with the end curved with a hot air gun, to stop the bend collapsing, I put a piece of silicone tube inside the ABS tube. I glued a length of hardwood dowel, split length ways into the tube so that I could screw this to one of the plywood frames in the engine bay to simulate the exhaust, it looks OK, but is not true scale in that it does not have the pipes in from each cylinder and is uniform along its length.

The full size plane I am modelling has had an air driven generator added at some point. This sits between the undercarriage legs. I have made up a reasonable facsimile of this using the rotor out of a 30mm EDF, it is not truly scale but represents what is on the full size plane. The rest of the generator is made up from 0.3mm brass sheet soldered together. Yes, the EDF rotor does rotate, the shaft sits in a length of brass tube.

Pitot tubes in the next post.

I have also reset the rigging wires so that I can assemble the wings properly onto the fuselage, after the rebuild everything was in slightly different positions and the wings would not fit back properly. I have checked the GoG and with the batteries in it is marginally nose heavy, about 15mm in front of the plan Cog. However, the plan CoG is for IC engine in the dry condition, when the fuel tank is full the CoG will be forward of the marked location, so I believe I am OK. I have weighed the plane and this comes in at 8.2kg = 18lb 1oz with batteries, which I am happy with given the amount of detailing that has gone on.

I have a couple of final jobs to do on the power side, I need to add an ESC arming plug because it is quite convoluted fitting the batteries and getting the cowl back on, hence a final arming plug next to the exhaust will safely make the plane live after all the fiddling about is done.

Therefore, as far as I am concerned, I have completed the build of the plane, I have no more detail to add and I should be able to Maiden it during May.

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PeterF28/04/2018 22:29:50
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318 forum posts
545 photos

The pitot tubes are made from brass tube plus 0.3mm and 0.15mm brass sheet along with some 3/16" brass hexagon all soldered together. As I looked into making the pitot tubes, it dawned on me that there is no such thing as a standard pitot tube layout and many moths have had slight changes made over the years. Therefore, I looked closely at the full scale I am modelling and it followed the most common pattern, however, it has 90 degree compression fitting type unions connecting the pitot tubes to the impulse lines which is unusual. I do not have a drawing of the pitot tubes, hence I used a photograph of the full size plane and printed this out suitable scaled to give a template to make the pitot tubes against. This allowed the tubes to be bent correctly and the side plates to be cut out.

I made the compression fittings from the hex bras with grooves cut in using the parting tool to simulate full size ones. They look OK, although one might complain that it is unusual that the flats on all of the nuts line up with each other, which would not happen in reality. Everything is soldered together, which has meant some judicious use of the iron to stop everything falling apart if I allowed the whole assembly to heat up too much. The pitot tubes were bent to shape, end pieces made and soldered on then the 0.15mm sheet was used to attach the two tubes together as one assembly per scale. The sides were then attached with 10BA nuts and bolts and soldered where they wrap around the pitot tubes. This impulse lines were added along with the compression fittings and bent to shape. The assembly was painted and attached to the interplane strut and the usual 0.5mm aluminium and rubber straps added. The brass tubes stop short of the wing surface, I did not want to puncture the Solartex.

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Manish Chandrayan02/05/2018 15:33:34
397 forum posts
56 photos

Absolutely fantastic, that's how the model has turned out. I for one can't wait for the maiden flying report and please do have some one record a video of the maiden even if it's using a phone camera

Martin McIntosh02/05/2018 17:46:17
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2393 forum posts
930 photos

Puts my feeble efforts to shame. Very well done.

Manish Chandrayan02/05/2018 18:50:55
397 forum posts
56 photos
Very well said Martin. Couldn't agree more with you sir!
Richard Thornton 203/05/2018 18:25:21
11 forum posts

Cracking job on the pitot tubes Peter. Its very easy to start one end and just as you finish, you get too much heat into the assembly and it falls to bits.

What size brass tube did you use?

PeterF03/05/2018 18:34:30
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318 forum posts
545 photos

The pitot tubes are from 1/8 inch, the larger diameter end of the lower tube is 5/32 inch, which slides over the 1/8 tube ( K&S). The vertical impulse tubes are from 3/32 inch. The brass hexagon used for the compression fittings is 5/32 inch. All sizes worked out by measuring a photo.

I had a couple of joints part company but not too bad. Ideally you could buy a series of slightly different solders and use increasingly lower melting points as the build progresses.

Richard Thornton 203/05/2018 19:24:00
11 forum posts

Many thanks Peter

I have tried to measure the sizes off a photo, but due to the odd angle i took it, i felt it was unreliable.

I forgot to say, those joining pieces are cracking too.

PeterF03/05/2018 19:54:11
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318 forum posts
545 photos

The wind has been unkind this week so I have not been out with the Moth. However, I put it together in the garden for a final check a few days ago, the last thing to do was to check that after the covering and rebuild, the ailerons were still set correctly and the control wires on the servo actuation arm and return arm all worked OK. I needed to rejig the wires a little and the rods between the servo discs and the ailerons, obviously, things had moved slightly during dismantling and rebuild. Here is the model after all the scale detailing has been completed.

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cymaz03/05/2018 20:00:40
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7536 forum posts
975 photos

yes

KiwiKid04/05/2018 12:49:05
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386 forum posts
363 photos

Have really been enjoying your build thread Peter, particularly as I have a two thirds built Tiggy on the go. Your problem solving and scale building has been inspirational - totally amazing project.

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