Karaya Supermarine Sea Lion II - 1922 Schneider Cup winner - 1/72nd resin

[fjaweijfopi4j48]

The kit's stabs are molded as if a small part of them at leading edge exceeds the fin and meets, which I don't think is not accurate.

Their roots have to be re-carved a little bit so the hinge line coincides, and they do not exceed the fin's leading edge.
No locating devices are provided, so you have to resort to a metal pin and very careful drilling of the stabs.
Do not forget that in this plane the convex (bumpy) side of the horizontal tail airfoil goes pointing downward, and the concave (cupped) side of the airfoil is up:
Since you are at it, drill the needed holes for the tail rigging:

 

 

 

Edited March 4, 2020 by Moa
modify a statement to avoid confusion

[fjaweijfopi4j48]

It seems that somehow we modelers got charged with quality control:
Here you can see 5 Roman numeral I struts and 3 number II (4 and 4 are needed). Simple, cut one of the larger to get one more of the shorter, but it would have been nice not to have to.
Not all struts are marked on the plan, so the tail group (numbers V) -consisting of three different struts- doesn't have any indication as to where they go, which is not very important, given that their disposition and number is inaccurate anyways.
Some (like the tail struts and perhaps the lower wing to fuselage ones) could just perhaps being carefully dropped in place, but those wing struts and engine ones will need metal pins if we want things to proceed with relative precision and safety:

[Andwil]

9 hours ago, Moa said:

Do not forget that in this plane the convex (bumpy) side of the airfoil goes pointing downward, and the concave (cupped) side of the airfoil is up

How did it fly?  This is the wing shape of racing car airfoils, designed for downforce.

 

AW

[Marklo]

20 hours ago, Quiet Mike said:

This morning the small blue wall plaque caught my eye. (I don't know if these are still peculiar to England,

We have similar here in Ireland.

[fjaweijfopi4j48]

10 hours ago, Andwil said:

How did it fly?  

I am no aerodynamicist, but I believe most wings require a tail dawn force momentum to counteract the shift of the center of pressure on the main airfoil, which otherwise compels the plane to nose down as it displaces along the chord. The tail makes the plane "pivot" on its center of gravity keeping the nose leveled. The use of a "reversed" airfoil just does what it is normally accomplished and performed by decalage, or angular difference between wing and horizontal tail (the tail "digging down" as its angle of incidence is lower).

The use of a reverse airfoil, already producing a downward force on the tail, may have lead to a lesser angle of incidence, therefore reducing drag.

 

Aerodynamicists interested on the subject may open a new thread (with a link here if applicable) if this needs further elaboration/corrections/refutation/comments, so we don't clutter this thread.

 

 

 

[fjaweijfopi4j48]

The hull is primed:

[Andwil]

I obviously misunderstood your post, Inthought it was both the wings and the tailplane with reverse airfoil, not just the tailplanes.

 

This makes much more sense.

 

AW

[greggles.w]

Excellent!

 

I am in part buoyed by your analysis of the strengths & weaknesses of a Karaya kit, which aligns with my own ongoing experience.

 

However I am equal parts sunk, despite the buoy, by the fact that you seem to be disproving my theory that these issues required the builder to take several years to finish the project!! Fast & fastidious work as ever Claudio.

 

Re images, I will once again offer you a link, not learning from past experience which should tell me you are always ahead of us.

Go here:

https://www.maryevans.com/search.php

 

And in search drop in this number (for some reason my ‘smart’ phone won’t give me a direct link):

 

11355581

 

It claims to be a photograph, but if so seems heavily retouched .. it seems when ‘they’ removed Trotsky the wing-walker they also erased the upper wing registration?

 

 

 

 

 

 

 

 

[fjaweijfopi4j48]

1 hour ago, greggles.w said:

Excellent!

 

I am in part buoyed by your analysis of the strengths & weaknesses of a Karaya kit, which aligns with my own ongoing experience.

 

However I am equal parts sunk, despite the buoy, by the fact that you seem to be disproving my theory that these issues required the builder to take several years to finish the project!! Fast & fastidious work as ever Claudio.

 

Re images, I will once again offer you a link, not learning from past experience which should tell me you are always ahead of us.

Go here:

https://www.maryevans.com/search.php

 

And in search drop in this number (for some reason my ‘smart’ phone won’t give me a direct link):

 

11355581

 

It claims to be a photograph, but if so seems heavily retouched .. it seems when ‘they’ removed Trotsky the wing-walker they also erased the upper wing registration?

 

 

 

 

 

 

 

 

Yeap, have seen that one during research.

Is useless.

Thanks for the good intentions, though.

Cheers

[fjaweijfopi4j48]

OK, I think it can be affirmed with a fair degree of certainty that the landing gear leg is not, as described in the kit, a bicycle front wheel arrangement, but a more common "sideways" fork into which the axle runs, very much like in the Sea King (the plane from which originated) and Sea Lion III.

So new parts shall be made, which are fortunately simple to fabricate:

 

 

[fjaweijfopi4j48]

The wing floats are glued. Their position is unmarked:

 

The new beaching gear.

If your gear legs came molded in good health (unlike mine) you may use them, locating them sideways, but you risk breakage anyway due the very low mechanical strength of small/thin resin parts:

[Courageous]

A good correction there Moa, duly noted. 

 

Stuart 

[fjaweijfopi4j48]

The control horns are glued on the tail. The kit provides exactly the number of these very small and fiddly bits that you need. I am overwhelmed by the manufacturer's generosity and foresight. They are a tad thick for my taste, and although I used them, I should have replaced them with photo-etched items that would look much better.

Then the tail and wing were glued in place:

[greggles.w]

.. that’s a very clean little monoplane 

[fjaweijfopi4j48]

24 minutes ago, greggles.w said:

.. that’s a very clean little monoplane 

No wonder, has its bottom in the water more often than not.

 

[JamesP]

Did you find the wing to fuselage alignment square? It was a tad out in my build and a "fortunate" drop allowed by to reset it. 

[fjaweijfopi4j48]

1 hour ago, JamesP said:

Did you find the wing to fuselage alignment square? It was a tad out in my build and a "fortunate" drop allowed by to reset it. 

The wing if you followed the peg and holes was askew, had to fiddle with the holes, thought was just me. Thanks for bringing it up.

[fjaweijfopi4j48]

Hello again.

After a week under the weather with this very persistent and vicious cold/flu, slowly getting back on my legs.

Far from healthy and recovered, very low ceiling, miserable radius, scant available power, and almost zero maneuverability, but I decided I will do whatever little thing can be done until full functionality is reestablished.

 

I decided after contemplating the kit's tail control horns in place that they weren't inline with the general finesse of the kit, appearing coarse and out of place. Therefore I started by removing them, then removing all tail control surfaces, and adding photo-etched horns. Now things look much better. Needless to say, If I have done this from the beginning, before gluing the tail in place, things would have been easier, but I am glad anyway I changed those chunky horns the kit provides:

 

 

 

[fjaweijfopi4j48]

Tail control surfaces glued back, with some deflection to liven the view:

[fjaweijfopi4j48]

The tailskid/water rudder and associated parts are attached. I substituted a weak-looking tiny rod for a metal length. The wing struts are cut from their pouring blocks, drilled and given metal pins, a task that took time and patience, given the small size of the parts. As described above the kit wrongly dealt 5 wing long struts and 3 short struts, so one was re-purposed:

[fjaweijfopi4j48]

We are in a bit of a pickle now, because I can't use the airbrush with my respiratory system as it is now to apply primer, so this will have to wait a bit.

And in the interim I will deal with the lack of the additional decals needed that the manufacturer missed.

 

[fjaweijfopi4j48]

The four aileron control horns are also replaced by metal items, and the holes for the cables are drilled, to represent the loop:

 

 A water rudder control bar present in the plane but absent in the kit is added in the form of a small length of thin wire:

[fjaweijfopi4j48]

Studying now the engine pan strut arrangement and a possible assembly sequence for the whole engine gondola.

A very poor job has been done here by the manufacturer regarding clarity in the instructions and overall engineering.

What goes where has to be deduced from a small and poorly printed section of the instructions. The set-up looks vague, and possibly inaccurate, plus the manufacturer seems to have confused the missing strut that goes from the center of the gondola to the fuselage spine for some diagonal reinforcement that triangulates the array, contradicting photos and plans.

A nice kit, and a very nice subject, let down by this kind of thing in more than one spot.

 

 

[fjaweijfopi4j48]

The four external struts of that array are also given pins to secure them.
Locations for them will have to be guessed and drilled on the engine pan:

[fjaweijfopi4j48]

The measures from the wing were transferred to a sheet of paper, and using five-minute epoxy the engine pan legs were glued and the whole assembly carefully aligned. This is not as easy as it sounds, but I had tried two other ways before and failed, and this worked. It will also help with airbrushing, since the unit can be painted separately: