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AW FK10 Quadruplane at 1/4 scale (80")

Four wings, eight ailerons and a tiny all-flying tailplane, so.....

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Tim Hooper17/04/2013 21:39:16
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2859 forum posts
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.....what could possibly go wrong? wink 2

This is the model that's been brewing in the back of my mind for some time now. Back in 2004 my very first own-design was a 1/10 (34" Quad) . I still have the model, and it still flies on special occasions.

Now that leccy power appears to have come of age, it's no longer a pipedream to build a 1/4 scale bipe in the 18-20 lb weight range. So having gained some stick time with my BUSA Nieuport 28, I thought I'd revisit the Quad.

This is going to be quite a long term project (surprise, surprise), so don't hold your breath, OK?

For anyone not familiar with the Quad, it was designed by Frederick Koolhoven when he was employed by Armstrong Whitworth back in 1916 - allegedly to try to expand on the success of the triple-wing Sopwith Triplane by adding yet another wing. The actual aeroplane was not a huge success (due to poor reliability and dodgy engineering), so only 8 were built.

There were two distinct variants, with differing degrees of stagger on the wings.

 

201-1.jpg

 

305-1.jpg

img_9599small.jpg

Research on the net revealed no less than four speculative 3-views, so I opted to base my model on the 1963 drawing of Jim Morrow.

armstrong%20whitworth%20fk-10 copy.jpg

So, progress so has been limited to putting pen to paper.

img_2348.jpg


Although all eight wing panels are pretty identical outboard, they do differ at the root ends, so I've drawn the roots as separate items.

img_2350.jpg

That's a one metre ruler to give scale.

The top and bottom wings joint together on the centreline, but the two intermediate wings don't actually meet each other, but end at the cabane struts.

Just to make life easy at the field, I want to try to make the wings detach as complete cells, thus;

img_9863small.jpg

Wish me luck!

tim

Edited By Tim Hooper on 17/04/2013 21:39:55

FastFlyer Smyth17/04/2013 21:45:27
309 forum posts
11 photos

Subscribed.

Good luck !!

Concorde Speedbird17/04/2013 21:52:30
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2717 forum posts
631 photos

Wow, this model will have a lot of presence, and even more drag! Should be interesting to follow (and no, I will not say anything about petrol engines, oh dear sorry!). Good luck and cue the building!

CS

Tim Hooper17/04/2013 22:01:24
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2859 forum posts
2363 photos

Thanks lads!

Here's a couple of pics of my 1/10 version. 34", 34oz. It started life on 7 small nicad cells (arranged around the motor inside the cowl), but now flies on a 3S 1800 li-po.

So, I'm not entirely breaking new ground here. The miniscule 5% tailplane was doubled in area, and its throws quietened with a dose of expo. Works well - well enough to inspire to have a bash at the bigger version anyway!

Next stage is to draw up the tailplane.

tim

Concorde Speedbird17/04/2013 22:03:26
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2717 forum posts
631 photos

Lots of linkages...

CS

FastFlyer Smyth17/04/2013 22:09:27
309 forum posts
11 photos

... and lots of ribs/riblets !!

GrahamC18/04/2013 07:39:27
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1232 forum posts
196 photos

I'm wincing imagining the cost of the Solatex!

Ill follow with interest!

Danny Fenton18/04/2013 08:46:58
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9106 forum posts
3945 photos

My word Tim your models are getting bigger and bigger, should be great to follow along. smile p

Cheers

Danny

Ton van Munsteren18/04/2013 18:16:20
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1279 forum posts
3301 photos

Tim,

What a great choice , what else can I say than, don't you just love those Dutch designersyes.

Ton

Tim Hooper18/04/2013 21:21:02
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2859 forum posts
2363 photos

Right, lads, here's the tailplane in all it's two-dimensional glory. Or one half of it, at least....

img_2353.jpg

Firstly, the dotted line shows the actual 'scale' outline, which equates to an area of about 5% of the wing area. Not enough, methinks! So, I've enlarged the dimensions by a factor of 1.4 which pretty much doubles the area. Up to a massive 9 percent. I did the same on my other baby Quad, and allied to a fairly forwards CG position, makes for a stable flier. Honest!

The mechanics are going to be interesting though. Trying to make an all-flying tail this large will be quite a challenge, even with a bracing strut underneath - because the tailplane has to pivot where it encounters the strut.

Incidentally, Graham, we have around 20 sq feet of wing area to cover on both sides with 'tex - and that's before we start on the fuselage.....smile o

Ton, that Koolhoven bloke was certainly prolific, wasn't he? I do have a little Desoutter Mk1 in my hangar (based on the Shuttleworth aeroplane). It also has a small tailplane, but the long moment arm helps to keep things calm in the air.

tim

Tim Hooper20/04/2013 21:01:49
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2859 forum posts
2363 photos

Regular sufferers of my scribblings will know that I favour the use of 'ladder' jigs to set the incidences, stagger and spacing of my multi-wingers. The Quad is no different except that it'll be a lot bigger than anything I've made up until now.

The interplane plane will be quite a monster. 45 wide and 6mm thick, I'm still doing mental somersaults trying to figure how to bolt the struts to the wing panels.

tim

img_2357.jpg

Rich too20/04/2013 21:08:09
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3023 forum posts
1070 photos

Following with interest....Rich

Stephen Jones20/04/2013 21:59:14
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2693 forum posts
1528 photos

Tim ......................... WoW ...

You really must like building wings , That would frighten me .

And the cost OMG

Well it`s beyond me .

I`ll just sit back and watch wink 2

Tim Hooper20/04/2013 23:00:35
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2859 forum posts
2363 photos

Steve,

Actually, building wings is no biggie really. Once the ribs are precut (an evenings work knifing around an ali template), and the spars and tips cut ready, then it's just a matter of laying down the lower capstrips, spars, ribs and upper caps - say, two evenings for each of the eight panels.

But to split it up a bit, I won't do them all in one block, but interpose other sub-assemblies in between, such as the tail surfaces, struts, under carriage etc.

As for the cost - well, let's talk about something else, eh? wink 2

tim

Tim Hooper21/04/2013 20:35:24
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2859 forum posts
2363 photos

......and another productive afternoon was had by all!

img_2361.jpg

Basically I'm copying the structure of the BUSA Nieuport, using 1/4 x 3/8 longerons allied to 1/8 ply internal doublers up front. I'm basing the size of the front former on the quoted diameter of the Mick Reeves Sopwith Pup item - 247mm.

I've also enlarged the rudder slightly

tim

Martian21/04/2013 21:26:39
2217 forum posts
1091 photos

good grief Tim that is a serious project I shall look forward to following this all the way through,me I'm still reluctant to put pencil to paper I'm still drawing in my head, you must allow me to invade to building space one day night or whatever

Tim Hooper21/04/2013 23:06:18
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2859 forum posts
2363 photos

Martian,

You have an open invitation to visit anytime!

Like you, I do a lot of pre-thinking before I commit pencil to paper. Then I do more thinking before I start to cut wood, which often prompts me to go back and revise the drawn plan. Sometimes more than once!

The final touches are drawn in after the model is built. Again, more revisions may follow.

What I'm trying to say is don't worry about drawing up a definitive plan in the first instance. A design sorts of comes together in its own good time as the build progresses.

tim

Rene Wallage22/04/2013 09:00:53
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128 forum posts
59 photos

You're shaming me into thinking I realy should start on my vintage Wolf glider drawings...

cymaz22/04/2013 09:09:34
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8656 forum posts
1175 photos
Good effort, well done. On the subject of wing ladders for a jig, I've got some 4"x2" in the garage if you need it !!!!!!
Tim Hooper22/04/2013 20:52:50
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2859 forum posts
2363 photos

Thank you Gents!

The next few evenings are liable to be spent sorting out some of the finer details of the design - fuselage cross-sections, undercarriage, etc - so nothing too dramatic coming up. I reckon that Saturday will herald a trip to Penn Models for some balsa sheet, although I'll probably bulk buy at SLEC or the Balsa Cabin.

Then again, I could always use spruce (instead of hard balsa) for the wing spars, and see what Homebase or the local timber yard has to offer.

tim

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