DH Tiger Moth 1400mm

[Manish Chandrayan]

Posted by Bob Smitham on 20/03/2020 12:22:24:

Posted by Cuban8 on 20/03/2020 09:13:07:

Posted by Manish Chandrayan on 20/03/2020 08:40:13:

Love that tank work, but please tell us what's that big bulbous thing under slung at the rear left of the tank ?

A drain sump to collect water, I believe.

It is and it does need scaling down a few percent .It's not easy to get an idea of the scale until it comes off the print bed and put on the model.I have a small pile of wheel hubs that were a little to small or large.And re scaling in Cura then reduced the the depth of the concave inner surface meaning the hub sat clear of the wheel rim.It was then back to the CAD sketches and pretty much starting again.

But isn't that one of the pleasures of a build the wide range of information and skills you learn.I didn't have a clue what a "Venturi" was called or its function until last week.No doubt these will take a few prints and edits to get right ish.

[LHR Dave]

Was reading through this post earlier and saw that Jon recommended the Saito 45 fs I have just seen one on Ebay the link is below.

https://www.ebay.co.uk/itm/143559493988

Regards

Dave

[Bob Smitham]

Posted by LHR Dave on 20/03/2020 16:18:16:

Was reading through this post earlier and saw that Jon recommended the Saito 45 fs I have just seen one on Ebay the link is below.

https://www.ebay.co.uk/itm/143559493988

Regards

Dave

I did see your link Dave but I have been reduced to using my phone for all tinterweb activity due to a fialing HDD on my PC.But like all the engines that would be ideal for this build the bidding went over my budget.And seeing has the present lockdown situation has reduced my hobby kitty .I'm keeping the Irivine .PC is now fettled and running so I'll post an update.

[Bob Smitham]

Those modelers of a nervous disposition please look away now!

Well a few minor set backs lets say have slowed me down a little. Most of the problems have been inexperience and me having five thumbs on each hand.The following is my catalogue of disasters that hopefully will help other first time kit builders.It is easy to judge yourself harshly when you see most of the build threads on here and elsewhere .And it is worth remembering years of experience will always trump youtube videos and build logs.No matter how many you watch.

The rudder and elevator linkages using fishing lure swivels works and was tested with my servo checker.I can't post many pics of these as alas they were lost on my old HDD.

I then removed the control horns wings and landing gear ready for covering(something I was not looking forward to).

The first set back was following this I locked my shed for the night but managed to turn on my fan heater as I turned off my work bench power.In the morning I opened my door and was met by a blast of heat.It had become so hot my roller blind had warped and also my fuselage.A slight twist from the turtle deck to the tail which left the elevator/rudder assembly sitting around 3 degrees from true.To remedy this I removed the last former from the frame.Then a few days of water soaking, clamps and weights and crossed fingers managed to pull it back to shape.

Another little disheartening clumsy accident occurred as I was sanding the fuselage.I turned the body over forgetting a clamp was still attached to the turtle deck.

At this point I was beginning to think i had taken on a project beyond my skill level.Stick to cutting and crashing foam I told myself.In the end the repair was easy and shouldn't be noticeable when covered.

Giving myself a break from the balsa I started experimenting with ideas for the wind screen.My first attempts at a frame for the glass were with .5mm aluminum sheet folded over the plastic screen.If the scale was larger this may have worked.But again my ambition had taken over my ability.I then returned to more familiar ground and the 3D printer and finished with some chrome car paint.

You can see the filled gap at the front of the cockpit.This was present before the heater incident ,other build threads have encountered other slight mis cuts on this kit.

The Irvine 46 will be staying (Covid and the furlough malarky has seen to that)so a bit of work was needed on the cowling to allow for the muffler and access to the idler and what have you .With some trepidation I took the the Dremmel to the fibreglass cowling and fashioned a door from the sheet aluminum that proved unsuitable for the windscreen frame.Now the problem of the hinge.Piano hinge was my first choice and trinket box and dolls house suppliers were my next port of call after not finding anything suitable on any RC sites.I'm not kidding myself that this will ever be anything but cartoon scale ish.But the piano hinges I could find would of maybe been ok on a 1/3 or 1/4 scale build, but huge for this scale.I eventually found some small hinges with a diameter just the right size for threading piano wire through and daisy chaining the jewelry box hinges after removing the existing pin.Lining up drilling and fixing this DIY hinge was fun and the end result wasn't that good.

If I was to start afresh I would probably used the smallest piano hinge I could source fastened with epoxy on the inside of the cowling and maybe replicated the riveting with a blob of PVA technique I have seen on build threads.

The fuel tank is now fitted and a thin epoxy mix was applied inside the nose area for fuel proofing.The top picture shows the removable battery tray and throttle servo housing.I worked on the premise that I will eventually get a leak or faulty servo so wanted this section screwed in place rather than a permanent fix.This will allow fuel tank removal without too much faff .Next problem was the throttle linkage a simple dog leg wasn't going to do it so a bearing and printed bracket was knocked up using ABS that has a 220 celsius melting point.( will run the engine a few times to see if the heat upsets this material) I also have some nylock nuts on order for the engine mount bolts.A quick question on the engine mounts, is a fiber or nylon washer recommended ?

[Bob Smitham]

Well after long wait the covering film for the wings arrived.A 5 meter roll for around £13 with very positive reviews.My only previous experience with film was covering the wings of a foam Mini Talon kit and as I mentioned at the start of this update this stage was worrying me.I did decide on the colour before the kit arrived.I do like the Moth in yellow but there are a few ARF kits with this livery at 1400mm span and lots in camo.Being a Lancastrian a search came back with this example from The Lancashire Aero Club in 1947 and It was decided on.Built in 43 for the RAF and demobbed in 47.

This picture isn't from Barton Manchester the L.A.C field but from a Good Year air race at Wolverhampton in the early 50's.Dark navy blue,silver and a red stripe.Yes I have made it difficult for myself I now realiselaugh.Those stripes are going to be fun after my struggle with film on the wings.So in my warts and all post of a first time builders woes here we go.With the usual film covering errors and cock ups of too much heat chasing wrinkles and unsightly seams.Anyone thinking of giving it a go I'd say go for it.Unless you were born with an innate skill for all the disciplines involved in a build you will probably be disheartened at stages.And hours of work will result in some horrors fit for the bin.But just keep at it, each attempt is a slight improvement on the last.




I'm glad I got a five meter roll at a silly cheap price and any patching up is what scale modelers call weathering yes?blushI am thinking of getting another roll and starting again a little more sanding on the ribs is required this became blindingly clear when the film was shrunk. I'm not happy with the results from the covering so at £13 a pop I reckon another attempt will be made in the future.The next stage will be covering the fuse in blue and finding a paint match for the fuel tank and cowling.

Expect an update around December at this rate
Cheers ,Bob.

[Martian]

Loving your work Bob and admire your perseverance, this is the great thing with modeling the joy and satisfaction of getting it right after some struggles,

[Simon Chaddock]

Bob

Superb!

That is amazing detail.

Unless you can find an motor that goes the same way round as a Gipsy the prop will be wrong too. .

[Denis Watkins]

Amazing work Bob

And that lovely primer looks like you are working in the De Havilland Factory

[Bob Smitham]

Thanks for the encouragement fella's.Another twenty years and a few more builds and I may just get there.

[Bob Smitham]

Well I did say an update by Christmas.Here it is.

After my miserable attempt at the wing coverings things slow down a little.I consoled myself with flying my mini wing and for a month the Moth was well Moth balled (sorry).

Covering the fuselage was a little less troublesome than those open wing ribs.But I have still seen cheap bacon with less wrinkled wrapping .The wings are going to be given a second attempt.I have recovered both upper wings.And they are an improvement on the first attempt so progress is being made in that department.

I was fortunate to find a spray paint that matched the dark blue covering almost perfectly.Halfords Vauxhall Regatta Blue for the cowling and fuel tank

A four stroke would have been perfect for running the muffler out under the cowling.But as a first time budget build and test mule, I want to keep this project within a reasonable budget.I did scour the tinterweb looking and measuring the available pitts style units.The size of the cowling would still have required some cutting out. So the dremmel was powered and the cowling abused.

I had to add a pilot so the printer was fired up and few laser jet then cut out instruments stuck on the 3D printed panel.Again the end product was a little rough.

The next build will be better hopefully with the lessons learned.

I'm planning on finishing before the new year.The lower wings to be recovered is my next job.Then just a few bits and pieces BEC and RX TX set up and what have you.

When she's done I will do a few soft focus shots from a distance and update.

Cheers ,Bob

[GrumpyGnome]

Looks good Bob. Better than mine ....

GG

[Bob Smitham]

Thanks G.G ,I will post a gallery of shame of the rough bits when it's finished.

[Bob Smitham]

Well the recovering of one lower wing went well.But only when the glue had set on the brackets that hold the wing struts in position.Did I then realize they were reversed.A fresh exacto blade and several curses and an hour later I managed to free them with little damage to my new covering.Oh a bunch of bananas thrown in.

After correcting the error with the brackets the crossed piano wire piano connecting the two struts was misaligned .I hadn't noticed on the assembly before covering that the upper wing was being pulled away from the fuel tank.Every odd length I had in my spare was just a tad to short.An order for more has been placed but with it being this time year I expect it to be in the new year until it arrives.Plenty to be doing in the mean time though so not a disaster.

For the battery and BEC I have fitted the front cock pit instrument panel on a draw and hope to tuck them away .I will need to add a clasp to prevent the whole lot sliding out during flight.

Being my first build what batterys for servo's and RX will be sufficient ? I was planing on using a 2S Liion pack.

After tomorrow list of jobs from the wife is done I'm hoping to put the rx in and adjust linkages and servo throws.

Bob

[GrumpyGnome]

That's a neat solution for the Rx batter! Why do you need a BEC? I thought it was infernal consumption powered.......

GG

[Bob Smitham]

I'm using the BEC as simply to widen the battery options. I'm putting the FrSky SR6 in which is rated 4-10v. fine for But have a few Small 3S packs. that will fit. I do like my FPV as well. I intend eventually to put a small cam and pan n tilt set up on 9g servos that I drop in the front cockpit when required..

[Chris Walby]

Really great job you have done so far, don't be disheartened about setbacks just have a cup of tea/coffee and carry on.

Almost all of my ic and a few of the electric models in my collection use lipos and UBEC's, as you say handy as they are for other models. This is a really valid point for me as they get charged and discharged as flight batteries and any shortcomings are easily found before they die. This then means that for relatively low load of servos and RX there should not be a problem. I use anything from 2S1000, 3S800 to 3S2200 (needed for C of G) for RX/servo power.

I had a discussion with a very experienced modeller/supplier of modelling components (all types of electric flight) and he had a very good point regarding specifying large capacity UBECs (20A), if a servo fails then the current burns the servo out without letting the voltage drop below the RX min voltage. And as we know lipos are good at delivering plenty of amps.

PS - I have used many things to prop the model up, but had never considered fruit (nice bunch of bananas!), nice one as I did have a laugh

[GrumpyGnome]

Ah, gotcha re BEC

GG

[Robert Parker]

Hi Bob,

I have just looked at your build and I must congratulate you on building a fantastic looking Tiger, for a first balsa build you have great skills in both balsa bashing and the dark art of 3D printing. I like your total honesty of your mishaps that have happened along the way but that is all part of learning. I try to aim to make the next model better and learn from the little errors made, I'm still learning after 30 years.

Good luck with the maiden.

Just one point, ( I learnt the hard way), you will need to apply fuel proofer to the Halfords paint as fuel softens it and after a short time when you clean the model after flying your cloth will be coloured with the paint.

Here's my 66" span Premier Kit Tiger coming in on yet another dead stick landing, on-board glow system has put a stop to this events, Just Engines system fitted works great.

Regards

Robert

[Bob Smitham]

Thanks for the encouragement and advice, fuel proofing I will add to my list.The UBEC is a 20a so should be good on that front.The bug has bitten now my work bench is being cleared and the next build is being pondered. The struts have been sorted a length of wire was found in the shed.As for the maiden I think I'm a while off yet.Iv'e taken the plunge and contacted a local club.I couldn't have asked for a warmer welcome.My email was replied to within an hour and will be meeting the club secretary weather/ lock-downs permitting between Christmas and new year.He's bringing the club trainer and a buddy box to see where I'm at flying wise.And all this while the club are in the middle of a field move.And by coincidence he has just finished his lock down project,a Moth of all things.So things are looking good for the spring.