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Jun 13, 2009, 05:59 PM
A.J.
Build Log

Another Ivan's Short Sealand 480


Hi fellow builders and flyers

After several foam, plastic and balsa ARF models I have decided to do a real scratch build. I have never done this before (except for a simple freeflight glider with doped paper wing back when I was a young boy) so it's gonna be a real challenge. I live on a small island with no area usable as airstrip so I only fly seaplanes or floatplanes. When I came across Team Tracon's fantastic picture galleries from Chilliwack I was soon hooked. I just had to build one of those floaters!

As a balsa newbie I've read most of the build logs around the web and in this forum soaking up all the information I could. I am planning to steal all your great ideas and put them together, hopefully to something useable.

One thing I have been missing reading the logs are a little more details in how to do the basics, putting together the framework and so on. So I am planning to add additional photos during the build to show more in detail the process. It will of course be more of a chance for you to spot my errors than a guide for other builders , but it'll might be a good way for me to get guidance from the rest of you.
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Jun 13, 2009, 06:18 PM
Scott Quinn
siddus's Avatar
Aff,

Good luck with your build, Im sure you wont have any problems theres a wealth of understanding available from other builders . . . Keep the pictures coming it will help with enthusiam and motivation etc . . .

Siddus.
Jun 13, 2009, 06:31 PM
A.J.
Thanks Siddus, yes that is what i'm hoping for. I should be in good hands here
Jun 13, 2009, 06:37 PM
A.J.
Its funny how much equipment you end up buying when putting together a workshop. Better not think about the total amount spent..!

I really liked the magnetic building board solution so I decided to make one. I've used standard 1" fibre board as base plate and hot glued a couple of 100x50 cm steel plates to it. It seems difficult to get hold of square magnets I ended up using flat round neodyniums which I CA'ed to ply to make fixtures.

I have occupied the main dining table so me and my wife better not invite too big a party for dinner in the nearest future..
Jun 13, 2009, 07:58 PM
Two left thumbs
I'm signing on for your thread. I like magnetic building boards and Ivan's designs, so I'll probably learn something about both!

Geoff
Jun 13, 2009, 09:22 PM
A.J.
I decided to build the wing with full-length ribs as it looked more difficult to get them straight and true when in two pieces. To be sure the wing stays straight from tip to root I chose to use upper and lower main spars on the outer tapered wing panels as well, but I've used 4x4mm (approx. 5/32) balsa on these instead of bass to save weight.

I glued the ribs to the lower main spar and rear spar first, and didn't glue the inner leading edge contrary to most instructions. I think it will work out ok, all ribs were lined up and pushed against a magnetic straightedge. Small pieces of 1/16 are placed under the front of each rib as spacers for where the sheeting will be. Will also use spacers under LE when glueing it but at this point I had more than enough parts to keep lined up without adding one more factor!

I've read that the shear webs should have the wood grain running vertical for max strenght, but for my first build I found it a lot easier to cut and fit them horizontally. Anyway the original plan is showing a single horizontal balsa spar so it should be more than strong enough, especially with the added spars.
The main spar is build up as an I-beam.
I didn't make any fancy slots for the webs, just lined them up at the middle.

I bought ready made TE-strips, they should fit the design pretty well.
Jun 13, 2009, 09:40 PM
A.J.
Thanks for joining inn Geoff. Don't look to closely at the fixtures though, they're not exactly precisionmade! I've seen others making real art out of them, where mine are roughly cut and unsanded. but at least they are straight edged and will do the work
Jun 13, 2009, 11:08 PM
Two left thumbs
Those fixtures are doing a fine job! Very clever fixture for holding the trailing edge down. I've just been using the large, flat magnets from old CD/ROMs. Your way is better, so I'll steal your idea!

Geoff
Jun 14, 2009, 03:20 AM
Registered User
Trevorh's Avatar
Quote:
Originally Posted by Affi75
I've read that the shear webs should have the wood grain running vertical for max strenght, but for my first build I found it a lot easier to cut and fit them horizontally. Anyway the original plan is showing a single horizontal balsa spar so it should be more than strong enough, especially with the added spars.
If this really is your first 'balsa build' then I am mightily impressed! Keep up the good work.

True, vertical grain on the shear webs is best but, as you say, on this wing, it won't be critical. If you are careful to keep the rib spacing consistent, the easiest way to cut the webs is then to cut a sheet of 1/16 balsa to the width of a rib bay. Then just drop it in behind the spars and score it along the top spar. The taper on the spars is not really an issue if you rotate the sheet 180deg before dropping it into the next bay. The thing to remember is that, as long as the webs are firmly glued to the spars, the joint between rib and web is less critical.

Good luck with the build.

Trevor
(Sealand build diary here )
Jun 14, 2009, 05:54 AM
A.J.
Thanks Trevor, well i've done a lot of research before I started. think I've read your log 3-4 times already! Good source of info
You have a point there, it would have been easier to fit the webs behind the spars. That will be the way to go on my next build! (I love Ivan's Twin Otter, that is really a stunning looking model. Should work well with floats?

There is not much details in the plan about the centre section, like the raised fairings where the wing meets the fuselage. How did you make those Trevor, are they built up or is it a balsa block shaped to fit?
Last edited by Affi75; Jun 14, 2009 at 09:40 AM.
Jun 14, 2009, 09:08 AM
A.J.
I want to build in as many scale details as I can manage, so even if this makes the build harder I will enjoy doing it.

The ailerons will be modified to frise ailerons, with the hinge recessed into the control surface. They are designed very wide on the plan, so to make it look more scale I am decreasing the span by one rib, starting from rib #2 (instead of #1N) and end on #7.

I use flaperons on all my other planes but now I got the chance to make proper flaps.
The original schematics shows that the plane had both inner and outer flaps. I am only making one working pair, but I'd like it to look like there are two.

The flaps will be a slotted type that increases the airfoil area as the control surface moves both out and down. I am not sure what type of flap the original Sealand had, but from the pictures i've found it doesn't look like a fowler type.

I will make the flaps span across the inner three ribs from the fuselage. This leaves a three-rib span in the middle to simulate outer flaps. The wing taper starting point doesn't make this design look that well, so I decided to do a medium tapered section in the middle, but only on the trailing edge. This way the outer flaps will have a straight edge. In this process I took the chance to pull the outer panels back so that the leading edge is even with the middle panel.
Are there a reason to why the design had this step between centre and outer panel?
Last edited by Affi75; Jun 14, 2009 at 09:14 AM.
Jun 14, 2009, 11:35 AM
Registered User
Trevorh's Avatar
Quote:
Originally Posted by Affi75
There is not much details in the plan about the centre section, like the raised fairings where the wing meets the fuselage. How did you make those Trevor, are they built up or is it a balsa block shaped to fit?
I made mine from 1/16 sheet. Wait until you have sheeted the fuselage top, then fit formers to the wing l.e. and t.e., leaving room for the thickness of the sheet. Then I find it best to make a card template and keep trimming it until it blends into the wing. It's a 'cut and try' method - but then, most of my building is like that!

The NACA cuff step between the inner and outer wing panels is Ivan's favourite anti-tip stall measure. If it bother you, I reckon you could omit it as long as you have a bit of washout in the outer panels and keep the weight down. The Sealand is a very forgiving model - it has to be when you haul it off its belly from grass and find the nose 45deg up with no airspeed!

BTW if you are pursuing scale fidelity, I assume you will abandon the full depth rudder?

Trevor


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