SA6 Short Sealand from Ivan’s plans. - RC Groups
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Apr 25, 2008, 06:04 PM
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SA6 Short Sealand from Ivan’s plans.


I’m a long-term leaner on the door-post at the workshops of RCG but this is my first attempt at a thread. I started building a Short Sealand from the Ivan Pettigrew plans late last year; I have been keeping my own log of progress and hopefully there are some pictures with this post.

Reading the threads here from other builders of Ivan’s designs – especially the flying boats – has been a very useful and enjoyable exercise indeed – thank you! Who could resist the flying shots and videos, collected together on Luke’s thread?

We all have different ideas and approaches to a build, so it will be good to hear from other builders and hopefully, to compare notes and ideas. Are there any more new Sealands or other flying boats out there under construction?

The Sealand’s wing will be in three pieces for easy transport (it has to go on its holidays in order to get to water!) I’m also weighing all wood to (try to!) keep the weight low. If there is any interest I’ll jog along with a few more posts until I catch up with present progress – catching up is unlikely to take too long though, given my rate of building!

Having decided to construct a three-piece plug-in wing - and as the one straight line in the structure was the wing top surface - the three panels were jigged upside down on the building board. If the pictures leave any questions please say. The method was to use all ribs whole without halving them; to try to avoid ‘fit’ problems by check-drawing all the tapered outer-panel ribs; to produce the constant-chord centre-section ribs by the ‘sandwich’ method and to control weight by using selected 6lb stock that was firm... well, you can but try!

Paul W.
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Apr 27, 2008, 12:22 PM
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Constructing the wing panels.


I have decided to use a wing with the same sections and cuff as the plan but modified, with removable outer panels and a front ‘D’ box: there are partial sheet skins to the trailing edge, all connected by cap-strips. This gives a strong structure with ‘I’ beam ribs and no unsupported butt-glued joints. I hope this will yield a small increase in weight and a large increase in strength. Hopefully... Well, fair exchange is no robbery, so they say.

The balsa I am using is 6lb per cubic foot but firm stock. The structure needs to seem almost flimsy in build and just strong enough when finished – eek!

Having arrived at the stage of having a mostly-stable pair of outer wing panels, (sheet on one side) I next needed to fit the joiner tubes. The wing-ribs taking these tubes had been fitted with finger-plates in 1/64th ply. With the wing panels lined up, I slid a piece of sharpened piano wire outwards from the centre-section and through these plates in each rib, in turn. This gave an accurate alignment – I hoped.

Needless to say, when I checked before gluing, whilst one outer panel was spot on, there was a just-noticeable ‘spring’ to the other panel – the wing tip wanted to lift from the board. Relieving the top and bottom of successive holes in the wing ribs cured this - but leaving a sloppy tube-fit. The answer, finally, was to fit some tight ply ‘washers’ to the tubes and slide them up to the ribs, where they were epoxied in to place. Finally a good fit with no slop! You can see these washers in the pictures. I also fitted them on the other panel to match everything up.

In hindsight this was so easy, that what started as a work-round to a problem (of my own making!) turns out to be a useful easy-alignment method that I’ll use again. Well, it was new to me!

Paul W.
Apr 27, 2008, 01:08 PM
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Based on the comments of other Ivan's plans builders, I feel intimidated by the prospect of building one, so my hat's off to those of you who've done it, or are doing it! I'll follow your progress.
Apr 27, 2008, 04:06 PM
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Hi Geoff,
Thanks for that, I'm a glutton for encouragement! It's the comments from other builders that have helped me avoid some of the pit-falls so far in this build. This design takes me back to childhood and those stick and tissue gliders, like the KK and Veron kits. Ivan's designs certainly do fly very well - all I have to do now is to continue to push myself to finish it!
Paul W.
Apr 27, 2008, 04:55 PM
Two left thumbs
Quote:
Originally Posted by paulbw
Hi Geoff,
Thanks for that, I'm a glutton for encouragement!
So you're normal! I suspect that Luke Z's Short Solent thread has tripled Ivan's plans sales! You'll succeed, I have no doubt, thanks to all the threads and helpful people here!

Now, If I just had a little help building my home-designed Douglas Dolphin...
Apr 28, 2008, 03:06 AM
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Quote:
Now, If I just had a little help building my home-designed Douglas Dolphin...
Hi Geoff,
I have just looked up your thread and you don't appear to need too much help! It is certainly the case though, that building an own design airframe is a very intensive process - (but all problems are soluble in beer, so I am told!) Love those radials and the cowlings you have come up with. The Dolphin appears to be not too dissimilar to the Sealand in concept..??

Another prototype that I'm building more or less suggested itself too me when I walked past a soft-drinks display: this one is own-designed and nearly finished... Nearly! Having two or three builds in progress keeps me interested because I can swop between them - but it does mean that the progress on each is a little 'stop/start'.
...and I thought a plan-build would give my tired brain a rest!!
What progress with the Dolphin?

Paul W
Apr 28, 2008, 03:49 AM
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mountainman2442's Avatar
Paul,

So you don't think Geoff is the only one reading your thread, I'll chime in and welcome you to the "Brotherhood of Ivan"!

Beautiful work on the Sealand. It appears that I'll be learning much from watching your build. Your methods appear to be very precise.

Your method of attaching the outer wing panels is interesting. How are you securing the panels together at the fixing points? Is there built in washout at the wing tips on the Sealand as well?

John
Apr 28, 2008, 08:26 AM
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Hi John,
Good to hear from you. Your threads are always on my reading list and I can only gaze in admiration at your swift progress with that pugnacious Beverley -and before that with the Solent - good job! She will look very good indeed in that colour scheme. Whether or no you have her ready for your deadline, I hope she rewards you with much faithful flying service and I await news of your successful maiden!

The Sealand wing, to answer your questions, was built upside down on the board, being jigged on alloy strips for the centre-section and using a pre-cut tapered balsa wedge for the entire trailing-edge length of the outer panels. It was then easy to set a washout of 1 1/2 degrees on each panel. I used a dis-mounted Robart meter along the tip ribs to get them matching exactly.

There is already a designed washout, given the more cambered wing section outside the cuff which is as per Ivan's plan, so I'm not fully convinced I needed to bother with this, but there you go.

The wing-mount system will be thin metal tear-drop plates top and bottom, screwed across the joint in to the beech 'knees'. This will give me a simple fixing system that is visible and inspectable externally - good or bad, depending upon your point of view! The wings will stay in one piece unless being packed to travel with all the rest of the stuff that goes on holiday (to get to the chosen water in Wales). As long as the three sections stay put in flight I'll be happy though!

Thanks for declaring an interest - a second reader no less(!) - and for your kind words. My own deadline says that this build will be finished for October so although I've plenty left to do there is time still to do it - I hope! Your last Beverley post looked to be pretty close to completion? Good luck again with the maiden.

Paul W.
Apr 28, 2008, 10:40 AM
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RiBell's Avatar
Paul:
A few years back; I recived a Hanger-9 Funtana as payment for building a Sealand. Since you are wanting to go with a 3 piece wing so before you get too far into the wing
TIP FLOATS my $0.02.
I would make the tip floats removable, not as Ivan has done with a little square glued to the top of the float strut; and a small screw into the wing; where the screw can get lost; and the threads into the wood can get stripped. But rather I would make two wing ribs where it attaches. I would then space them 1/8" apart, making a pocket, that the center board of the tip float strut will slide up into. Use a couple of magnets to hold them in and then they can be removed and installed without tools.
Rick
Apr 28, 2008, 11:12 AM
Student of Ivan
mountainman2442's Avatar
Paul,

Thank you for the further information and the compliments .

This is the first time I've heard of building a wing in this manner which can either be attributed to my naiveté or your innovation... This will have to be one of those techniques I try in the future.

I look forward to the rest of your build and plan to interject a question or praise along the way...

John
Apr 28, 2008, 04:19 PM
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paulbw's Avatar
Hi Rick,
Thanks for your reply - that is a neat and practical solution for floats. I have yet to use magnets except those supplied in an ARF for canopy location and hadn't considered them at all for this application. My posts are still playing catch-up with this build - I am new to the delights of posting - I fear I may have got past the stage where I can easily use a double rib.

In my impatience to keep the build moving I simply installed a ply plate in the relevant position, deciding to do the float-thinking 'down the line' and maybe use some angle alloy pieces as brackets to pick up the struts, or maybe a rod/tube system. Your idea sounds good and I will employ it shamelessly in a future build if I can't in this one.

I'd been following your Lancaster thread - how is it coming along? I have a short kit of the Lancaster waiting for me to get to it!

Paul W.
Apr 28, 2008, 04:33 PM
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Hi John,
You are very welcome, and as to questions or suggestions please do! I've just mopped up techniques along the way and added bits of my own - in the quest to make life as easy as possible and to not have to correct too many mistakes - as we all do I guess!

Paul W.
Apr 29, 2008, 04:52 AM
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Wing panel construction, part two.


The rest of the wing structure has been a question of carefully working through and fitting all the detailed bits, location pegs, fiddly triangulation of end-ribs etc, before reaching the simple pleasures of closing up the sheeted areas, adding cap-strips and the rounded wing tips. (Later Sealand aircraft had a slightly extended span with rounded tips, which is how I’ve decided to build mine, resulting in a span of 81”).
This all sounds pretty simple when described this way, but there was, I’ll freely admit, a fair amount of fiddling and thinking on the way, witnessed by many empty mugs of tea – mostly courtesy of the management of this little Short Bros outstation - thank you Sara!

The aileron spars needed their webbing and hinge blocks; I also finished installing the wiring tubes and cables. This also caused a decision to deviate from ‘scale’ – the original Sealand’s nav./running lights were not where I wanted them for easy visibility – and probably not where they would be placed if the full-size was being built today; so the wiring went to the middle of the wing-tips, not the leading edges.

I was working towards closing-up the wing sheeting with a cry of ‘finished’ – easily fooled, eh? Having marked-through the bottom sheeting and released the half-skinned ailerons, there was now a further pause whilst I worked on the ailerons, newly hatched from the trailing edge of the wing. The hinge pockets were made in the wing and in the ailerons, immediately under the spar; these were marked back through with a needle – hopefully, a hole at each end of the slot stops said slot becoming a split – ( Peter Piper picked a piece... did I really write this?!!) Would there be enough angular movement? Quick, pass the permagrit; yes, now there is!

After sheeting and cap-strips were added, finally, I was able to slide it all together. Suddenly, at last, I had a near completed wing.

The last picture, I took yesterday afternoon, just as it started to rain (!) It is of the wing at present, awaiting nacelles and floats – haven’t got to those yet! The Airframe Inspector came and sniffed at it, but refused to pose in the rain. Total weight in this state is 12.5ozs according to Sara’s kitchen scales – which I’d now better go and replace, sharpish!

Paul W.

Question: does a sniff mean that the wing is now signed-off or will I need a full paw-print?
Last edited by paulbw; Apr 29, 2008 at 05:34 AM. Reason: Didn't load photo captions.
Apr 29, 2008, 08:50 AM
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scratchnhover's Avatar
You are indeed a fine craftsman Mr. Paul. I'm enjoying both the detail in your posts as well as the art in your construction. This is starting out destined to be an amazing model.

Sniffs definitely count as a full signoff at this stage. Typically the reaction I get from Mellie (my Boston Terrier) is "call me when you're closing it up for final inspection" when she can make sure things look fully airworthy (and no doubt ensure her "baby" isn't forever lost inside in a tragic accident- said "baby" being the one I restuffed and thin CA'd back together a couple of times to keep Mellie happy )

Mike
Apr 29, 2008, 10:50 AM
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RiBell's Avatar
Quote:
Originally Posted by paulbw
Hi Rick,
I'd been following your Lancaster thread - how is it coming along? I have a short kit of the Lancaster waiting for me to get to it!
Paul W.
It's on hold right now;as I'm trying to get a "Shorts Solant" built for the May fly-in, originally I had hoped to finish it and the Solant. However It became quite clear that I wouldn't be able to get both built in time. So the Lancaster was set aside. I'll be getting back to it once the Solant is finished.
Rick


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