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Sea Fury 77 inch


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Empty work bench again and I needed something to do. knowing my liking for WW2 birds one or two people have suggested that I try the above. I have seen some superb examples flying and whilst I shall never get one to that level I am giving it a go, having been following the build of the Jerry Bates 80" version with a Laser 360V.

Mine is to be the 77" one from the Geoff Lord design from way back when with the plans and canopy supplied by Sarik.

Before deciding on the wood required I thought that the enormous cowl would be a good place to start since If I could not successfully make a mould then it would be pointless continuing. Unbeknown to me at the time Black Horse do one in the right size and could have saved me a huge amount of trouble.

Here is my effort which I am pleased to say eventually turned out OK. It was made in three parts and I prayed that they would match up.

Pics show the completed item and some of the plugs/moulds.

More in a bit.

 

Sea Fury 77 inch 001.jpg

Sea Fury 77 inch 002.jpg

Sea Fury 77 inch 003.jpg

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I now need to hope that the fus will match up with it.

Next was the fus former halves and F1. The plan only shows half formers, fin and tail ribs for some reason so lots of work doing mirror images to get the whole picture.

The wing ribs have been cut and finished with ply facing where needed around the u/c but I have kept this to a minimum of 1/32nd. The rib thickness has been reduced in many places since the original had, would you believe, folding wings although only the locking servos are shown, nothing to actually fold them. It also had working radiator shutters!

The original main spar was 1/4 birch ply, 34x2.5" and even with lightening holes would weigh a ton so mine is 1/8th med. balsa laminated to 2mm lite ply. All it needs from previous experience.

Getting the u/c rails to fit the ribs has taken nearly a day because of the very awkward angles involved so I must hope that the designer has got these right.

I am hoping that if I can keep the weight below 18lbs my Laser 180 will take it up but if not then a 300V would fit in the same relative space. Some hope of getting one at the moment.

Here is a mock up of the u/c rails before I actually start to glue things together.

Sea Fury 77 inch 004.jpg

Sea Fury 77 inch 005.jpg

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Absolutely fine by me. It’s the variety of approaches shared by many that gives each of us the inspiration to find our own balance for what suits and shapes  our building methods. I have read and learnt so much from build threads and without them I would have utterly failed to complete my B Taylor P47.  
 

BTW those main spars look plenty strong enough to me. 

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Having a go at the wing centre section now. Not at all easy since besides having to work around the original folding wings, each side tapers top and bottom and the `folding` bit sticks up by one rib spacing. I have tacked on the ribs, spars and shear webbing on one side so now need to rock it over and do the other. Anyone know the correct dihedral angle on the full size since I only have the short main spar stubs to go by?

 

I managed to lose about 90gm with the lightening holes.

Sea Fury 77 inch.jpg

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Got the basic wing centre section built and the retract units installed, along with the 6mm silver steel legs bent to the approximate angles and some 8x6mm tubing made to fit the ends and the axles. The units themselves are from what were previously air retracts with the cylinders removed and the front ends chopped off. I have used this method before and with suitable servos to drive them means that I can now use servo slows instead of bang up, bang down.

Loads of trouble now working out how to do the LE since I have no instructions or how to sketches. There are many anomalies on my plan regarding the way that the intakes are constructed but looking at Nick`s pics it is becoming a little clearer. More tomorrow I hope and some pics.

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Crikey, not hanging around Martin. LE on my Fury is just a 1/4 sq balsa set at 45 degrees to the cord line with the balsa sheeting taken over, trimmed back and then the other side sheeting taken over in turn. Makes for a fairly sharp and streamlined LE as per the full size but tbh it’s a not very ding resistant. When I get my wing back on the bench I think I will try to find a way to let in something firmer at the very front edge. 

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I noticed that on your pics. Mine is the more traditional 1/8th balsa false LE, then sheeting, then more 1/8th over the sheeting. I would have thought that the SF had a very blunt LE as did the Spit and Hurri.

I think that I have now worked out how to sheet the top of the wing center. The part over the central bit of the intakes can be cut so that it fits over the outer parts which then get a further skin over some very flimsy end pieces. A little difficult to put into words but hope to have it done with pics tomorrow.

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  • 1 month later...

The tail is built as a top and bottom half then they are joined. A silly way of doing it to me because it is more than twice the work. The half ribs on the plan were inaccurate and the two sides differed in span as I found out when it came to the join, also, before they were glued together they warped very easily but are now OK.

I have made a start on the fus. inner box by laminating 3/16th to 1/8th vertical instead of the shown 1/4 balsa with 1/16th birch ply which would have increased the weight considerably and the box is only there to support the former halves and provide something to fix the motor to. I can never see the point in ply doublers on a model of this sort. The firewall will be 1/4 light ply faced with 1/16th birch instead of a huge chunk of 1/4 birch.

Sea Fury 77 inch 009.jpg

Sea Fury 77 inch 017.jpg

Sea Fury 77 inch 016.jpg

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2 hours ago, Martin McIntosh said:

 

The firewall will be 1/4 light ply faced with 1/16th birch instead of a huge chunk of 1/4 birch.

 

 

 

 

 

This will rule you out of fitting one of our twins (if i ever get the made) Martin as it just wont be man enough for the job. You need a solid firewall of 3/8 birch minimum. I would reinstate the 1/6 ply doublers too as they will do a much better job of spreading the loads and will weigh next to nothing anyway and most of the weight will be forward. 

 

Its no good being light if it falls apart. 

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I can face the inside of the firewall at the rear after assembly if required. I weighed some birch ply of equivalent size to the doublers and it came to more than the total weight of my box sides. Admittedly my 50cc Hurri has a 3/8th birch firewall but the thing weighs 28lb.

I have to be realistic and assume that a 300V will not come my way in the foreseeable future.

By the way I have weighed the wing with its bits and pieces and it is just 35oz, the tail being 4oz.

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Some more done, with the basic box now made up and the rear longerons added. I built one half with the W pieces then reversed it and did the other over this to get them the same. The cross pieces looked simple enough but were difficult to get right top and bottom since the four part formers need to fit exactly. I shall find out if they do so tomorrow.

 The front end has been reinforced with some very large, heavy TE section which came as part of a job lot of wood so it is now quite substantial. Why somebody ever bought that TE beggars belief.

The pile of bits is the outer formers.

 

 

Sea Fury 77 inch 018.jpg

Sea Fury 77 inch 019.jpg

Sea Fury 77 inch 020.jpg

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Most of the outer formers now fitted plus a trial fit of the cowl one. Considering that this was presumably a hand drawn plan, then certainly redrawn, the shapes transferred to paper templates then balsa and sawn out, they have proven to be quite accurate. The fus. cross pieces at the rear needed a little massaging to avoid making a banana but I am quite happy with it so far. Not looking forward to sheeting that lot.

 

 

Sea Fury 77 inch 021.jpg

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