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Falcon 1/4 scale Tiger Moth

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Trevor Rushton18/05/2014 22:17:05
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181 photos

Following the successful completion of my DB Sport and Scale Tiger I am afraid that I have been smitten with all things DH, and have decided to have a crack at the Falcon 1/4 scale kit.

I've long wanted to build the Flair Tiger, but this comes in a bit over 7kg - my target weight both because of club restrictions (we are near Biggin Hill airspace) and my own level of ineptitude extending only to an "A" at the moment.

I hd a look at the Traplet one which looks good, but could not determine the weight. I considered the DB 1/4 scale Cirrus Moth but that is not quite 1/4 and I had a fancy for some of Mick Reeves 1/4 parts. (I was probably pushing my luck getting one of his 1/3 scale Tigers so discretion being the better part of valour I held out) then I came across the Falcon model and was unable to help myself - it comes in at 15lb, so if I can manage that and get some reasonable scale detailing in I shall be well chuffed.

More on the kit in a minute, but it was the Shoreham Air Display last year that started it all...img_5035.jpg

Trevor Rushton18/05/2014 22:28:25
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458 forum posts
181 photos

The Falcon kit comes as a sort of part work - you can order up packs as you need them or alternatively go for the lot in one go. I have to confess to taking the latter route, including the hideously expensive but brilliant scale flying wires and the u/c kit which is a work of art. One of the attractions about the kit is the huge amount of hardware - metal work and epoxy board.

see here

I have decided to go with a new Laser 155, the prototype had a 150 but I figured the small amount of additional weight at the front would be worth the penalty and there is quite a bit more power. I could have put in one of those 4 cylinder OS in-line engines - almost seemed rude not to but that would have blown my weight target (and my wallet).

Mick Reeves has supplied the instrument panels and compass kits and I have bought some of his rib tape and stitches. I will use natural Solartex for the covering with a couple of coats of non shrinking dope to fill the weave.

Not sure about the colour scheme yet, but I am tempted with the RAF red/white chequer finish per the Mick Reeves version; its all a question of whether that will add more weight and whether I can prevent paint bleeding under the masking - plenty of time to worry about that yet.

Trevor Rushton18/05/2014 22:35:06
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458 forum posts
181 photos

I called in at the DH Museum recently for some inspiration - therapy actually. Aside from the mosquitos, a chippie and lots of other bits they have a Queen Bee and a Tiggie. Whilst not a very big museum you can get up close; if I had had a bit more time and a decent camera I'd have done a couple of walkarounds. The Tiger is a crop sprayer variant, but I'm not tempted to go there! Anyway a few pics to whet the appetite:

photo.jpg

Note the gap under the fin I think that this is replicated in the kit. - you also get a sense of the rib stitching

photo-1.jpg

I don't think the furry chap is standard, but I wonder how many hours in his log?

photo-5.jpg

Trevor Rushton18/05/2014 22:38:56
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458 forum posts
181 photos

Found a great set of walk around photos on the Silicone valley Modelers site - they have loads of stuff there including plenty of RAF Chipmunks for those interested.

See Here

Trevor Rushton18/05/2014 22:43:44
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458 forum posts
181 photos

Started with the tailplane first; its quite big at 29.5" span. The parts are router cut and fit together perfectly; I am very impressed. The instruction suggests building vertically off the spar which felt a bit dodgy, but it worked well.photo-7.jpg

The other good tip was to tape the elevator and tailplane spars together to drill the holes for the Robart Hinges - can't think why I had not thought of that before.

john stones 118/05/2014 22:47:51
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10791 forum posts
1481 photos

Impressive kit Trevor, some work and enjoyment in storesmiley I like the red and silver scheme, it looks classy.

John

Trevor Rushton18/05/2014 22:47:54
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458 forum posts
181 photos

For some reason the other photos that I have uploaded are all inverted. Not sure what to do about that so will have to reload them unless there is a way of rotating them.

Trevor Rushton19/05/2014 20:30:29
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458 forum posts
181 photos

photo-6.jpg

This was what I meant by taping the spars together and drilling them for the Robart hinges - such a simple thing to do and much easier than trying to drill and fit them once the tailplane and elevator are built

 

Edited By Trevor Rushton on 19/05/2014 20:46:21

Trevor Rushton19/05/2014 20:45:02
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458 forum posts
181 photos

photo-8.jpg

I glued on the plywood reinforcing plates to the LE, (they come pre-drilled) but in so doing I have made it difficult to round off the leading edge - they form hard spots and unless you are careful its easy to take away too much balsa either side. Moral is to round off the LE and then fit the plates.

The two outer fixings are for the tailplane struts - they seemed to be a long way out from the fuselage but looking at the Haynes Manual I think the prototype ones do extend quite some distance and I am inclined to trust the drawings.

The fin bolts on to the tailplane and as far as I can see the model is very true to the original.

Trevor Rushton20/05/2014 20:37:23
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458 forum posts
181 photos

The drawings show Robart 309 hinges for the rudder and elevator. I know that this is probably a silly question, but I have a number of Robart hinges which I think might be 309s but I have lost the packet wrapper and am not sure what bit is measured . The photo shows the hinges as marked on the plan compared with the Robart hinge that I believe to be the correct size - as you can see its still a lot smaller than the drawing. I am inclined to think that I have the large hinges, but if anyone has an example of a Robart 309 could they confirm that I have got it right?img_0292.jpg

Trevor Rushton20/05/2014 20:44:18
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458 forum posts
181 photos

I have come up against a small issue with the plywood doublers that are used on the fin. I'm not sure that I have got them right. Essentially, the fin ribs slide over the rudder post leaving about 1.5mm either side. The ply doublers are glued to the edge of the rib and to the post, but they don't sit flush with the post and have to be bent to make contact with it. I have done this, but something does not feel quite right. I will try and show it on the photos. The alternative would be to place a thin bit of balsa packing between the doubler and the post so that its nice and flat. Same goes for the leading edge. You can see the distortion in the ply. Any thoughts?img_0296.jpgimg_0294.jpg

Trevor Rushton20/05/2014 20:58:36
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458 forum posts
181 photos

As I posted the last picture I realised that the top doubler is a bit too high and should have sat below the rib and not onto it. However, whilst that would solve the top doubler, it does not answer the problem with the others which are in the right place.

Another point to watch is that the rudder ribs are a very close fit over the rudder post - I managed to break two of them just easing them in to place. Not a big deal, but I should have rubbed the post down a fraction first.

img_0298.jpg

David P Williams20/05/2014 23:38:23
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864 forum posts
284 photos

I have a packet of Robart 309s in front of me Trevor, and they look just like yours. They measure 2 and 11/16ths inches long, and the packet says they require a 3/16 inch hole. Watching the build with interest.

Trevor Rushton21/05/2014 06:41:19
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458 forum posts
181 photos

That's great, thanks David; I will use these, the hole diameter is the same.

Gary Binnie21/05/2014 23:03:17
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515 forum posts
34 photos

Been busy then Trevor?! Glad your DB Moth flew ok.

Have lots of photos if you need them, here's a couple of the tail feathers during refurb in 2010.

Trevor Rushton22/05/2014 06:52:32
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458 forum posts
181 photos

Hi Gary,

yes, a little busy, I have also been getting my Airsail Chipmunk back to flying condition - too much to do! I like the pics of your tail feathers; comparing them with the kit shoes quite a few similarities in construction or at least the layout of ribs, diagonal bracing etc. the bottom photo confirms the flat sided approach that I was fretting about in my version of the same component.

I'm going to move on to the wings next only because my existing building board is not long enough for the fuselage and I need to get another one. I have no idea where or how I'm going to be able to put the aeroplane together, the workshop will need a radical rethink! Worry about that later.

Trevor Rushton24/05/2014 21:27:31
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458 forum posts
181 photos

Thinking about servos; I have some new Futaba s148 standard servos which I am thinking about using. What do you think about these or should I be pushing the boat out? I have never had any trouble with these servos so is there much to be gained by a more expensive set?

At 6v they provide 4.1 kg / cm. the control surfaces are quite large, but I am not anticipating that this model will be flying 3d!

The elevator servo is pretty well inaccessible once installed so I need to have a reliable unit.

I also need to keep the weight down.

I would welcome views.

john stones 124/05/2014 21:50:54
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10791 forum posts
1481 photos

Push the boat out Trevor

There are lots of good priced servo's about these days and plenty of time to chose during the build.

John

Trevor Rushton24/05/2014 23:28:27
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458 forum posts
181 photos

Thanks John

looking through the instruction sheet I see that Chris recommends HS 125 for the ailerons, I believe these to be Hitec units which are very thin. Any experience of Hitec?

john stones 125/05/2014 00:11:07
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10791 forum posts
1481 photos

I use hi tec all the time Trevor, as do a lot at our club, find them very reliable. Not too keen on the karbonite geared ones, on big stuff I use metal gears, never used the 125 so cant comment but they are lowish torque, 625 or 645 have much better torque will take 6 volts and fit in wing no bother, or you can spend a bit more and get digi's,

look them up at Steve Webbs it gives all info, and shop around you get good deals, Leeds model shop has been doing a good price on them.

John

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