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Old Jun 13, 2012, 04:48 AM
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I would use 1/16 x 1/8 upper spars and place the front one midway between the leading edge and the lower spar and the rear one the same distance behind so that the lower spar is centered between the two uppers. As for wing section, I can't imagine it would make a lot of difference which one you used but notice the l/e entry point is wildly different between the two. FWIW. Gary
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Old Jun 13, 2012, 04:58 AM
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United Kingdom, England, Lancs
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I think it's unlikely to matter much what you do for a wing section. the ones you have cut would be perfectly ok. I would suggest you insert top surface spars at about 15% and, say 60% to balance that single lower spar. As designed that wing will be prone to bending. A spar at the front would have a turbulating effect and should improve performance. These wings operate at seriously low Reynolds Numbers and therefore the exact section is not too critical. A polar would show a horrible graph! Just keep it more or less as AH drew it and it won't be too far wrong. If you consider the wing sections of indoor models where the leading edges are comparable to squared of tree trunks you will see that low speed flight is a long way from the outdoor fast flyers. Do indoor models fly well? Do they just!!
I'm convinced that a lot of guff is talked about wing sections for models except when we start getting into large, fast flying types. Then Reynolds numbers start to mean something! The wing section families make a difference, of course, such as the very thin sections used on F1 classes or the thicker uncambered types used for aerobatics but for what we're doing it is if little importance as long as we're in the right neck of the woods. Also, for models such as the Ajax, Senator and so on it's no big deal to build two or three wings with different sections and compare them in the field! Would make an interesting little project. The Senator has a great reputation for it's performance but why? when it's so similar the Ajax, Achilles etc. The reason as far as I have been able to ascertain is that multi-spar wing with it's effect on airflow and not just the section alone. A similar suggestion has been made for the Caprice glider which is also a notable performer. I stress that the above is just my take on this subject! I now await the input of the more knowledgable among you to see if I go down in flames!
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Old Jun 13, 2012, 05:23 AM
I like real wooden aeroplanes!
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Welcome to the world of vintage model aeroplane plans Colonel! I have learned the hard way NEVER to trust any plan I haven't drawn myself. I suppose it is not surprising really when we consider that most of the plans we are looking at now were drawn by the designer, who sometimes had no professional drafting training, then traced/redrawn by someone at the kit producers, then over the years more than likely subjected to all sorts of copying on machines which may or may not have introduced errors.

Anyway, bottom line is that I always check all the important stuff first, like are the wing ribs shown the same chord as the wing plan, are all the notches in the right place - and the right size - do the fuselage formers shown match the plan and side views etc etc. This takes time but saves a lot of angst later on.

Your specific problem of the die-crunched ribs not matching the typical section drawn on the plan doesn't surprise me, especially with a model which has been through several iterations as the Ajax has. I doubt that the differences in the sections are going to have any noticeable impact on the flying performance, so it is just a question really of choosing one and sticking to it. Personal preference would be to dump the floor board kit ribs and cut my own.

Regarding spars; Many models of the Ajax era were designed with just a single bottom spar, which, if you were a bit heavy handed with the dope pretty much made sure you finished up with "cow-horn-hedral". On some of my recent builds - e.g Tomboy, Cardinal and Spartan (which had two spars, both on the bottom) - I have added two smaller section top spars. These serve three purposes - they balance the spar structure to counter bowing, reduce covering sag and add some extra bending strength to the wing to cope with the fact that we are flying the models differently to they way the designer intended. Others, such as the Zephyr and Witch had single top spars, which are better, and other than changing the spars to lime wood in lieu of balsa, I built them "as per". Albert Hatfull had obviously learned a trick or two by the time he designed the Bantam and it has one bottom main spar and two top 1/8" square ones, so apart from sheeting the top leading edge I built that as designed.

On the Ajax I think I would add two 3/32" square or maybe 1/16" x 1/8" spars to the top as in one of your suggestions.

Oh, and BTW, I for one won't be in the least offended if you choose to ignore any advice/suggestions I have made and might make in the future - it's your build and you should do it your way and enjoy it, but it never hurts to get other views.
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Old Jun 13, 2012, 08:03 AM
So I'M meant to be in control?
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Ilkley, West Yorkshire, UK
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Gary / Bob / George - thanks for the advice & views - much appreciated. At the moment I'm erring toward the two 3/32" spars, mainly because I have plenty of it. But that could easily change before any adhesive touches wood!!!

Oh and you are right about rechecking everything to plan - making F2 to the shape on the AH plan makes it about 1/16" too large to fit between the longerons on the fuz part of the plan! Adjustment carried out. One needs to choose one's datum and continually work to that - in my case the AH fuz.

I drew a blank with my South African factory on the cork front (to face a building board) - they would only send it if I picked it up from another Corporation factory a hundred miles away where nobody has ever heard of me!. Finally got the bottle to drop a line to a supplier of ours in Spain, and within minutes got an email which begun "OF COURSE I CAN MY FRIEND!!! We have 5 thicknesses - which do you want?"..........
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Old Jun 14, 2012, 04:28 PM
So I'M meant to be in control?
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Originally Posted by Colonel Blink View Post
One needs to choose one's datum and continually work to that - in my case the AH fuz.....
This was demonstrated to me again today..... All the printwood in the Amerang kit was on 1/16" whereas AH had specified 3/32". Building a fin from 3/32" sq strip with 1/16" tip and base pieces just seems crazy and would require 1/64" packing pieces. So, based also upon my desire to build an electrified Albert Hatfull Ajax, I have realised that all the parts need to be recut from 3/32" sheet. I tried the 'iron photocopy' to transfer the lines to the wood, and was only semi successful. But some parts I could cut from this operation - but when checking some wingtip pieces against the plan I found they bore only a passing resemblance to the plan part. I am now using the 'pricking with a pin' method to transfer the shape of parts (from photocopies of the AH plan) to the wood, cutting them out and then furtling with them in conjunction with the plan, and the mating parts. Not quick, but still enjoyable....

One needs to choose one's datum and continually work to that...

So that's now the ribs, the printwood and the the fuz stripwood that I am replacing......
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Old Jun 15, 2012, 12:43 AM
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CB, May I suggest another approach? Don,t attempt to cut fin and wing tip outlines directly from the sheet. If you cut strips wide enough to cover the required pieces, butt join them where needed and assemble so they overlap the outline, glue up and allow to set. You will have a rather rough approximation of the shape. Then make a template from thin card and use it to mark the exact shape. Cut and sand to finished size/shape and you have a perfectly shaped item. True it uses a little more wood, this method but is easy and accurate. Round sanding sticks enable you to tidy up the inner lines and reduce weight a bit too. If you look at my Senator build log you'll see that's what I did with fin there. Wing and tail tips the same.
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Old Jun 15, 2012, 08:07 AM
So I'M meant to be in control?
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Thanks for the tip there, Bob! Will probably use that on the wing tips....

Speaking of which, one issue I have in my mind is the best way of getting the tip pieces to merge smoothly between the TE which will be pinned to the board, and the LE which (due to the undercambered section) will be c3/16" off the board.

Is it best to glue the two tip pieces together as a seperate operation, let them set hard, then add them to the gap twixt LE & TE when the rest of the wing has been constructed????
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Old Jun 15, 2012, 08:27 AM
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Originally Posted by Colonel Blink View Post

Speaking of which, one issue I have in my mind is the best way of getting the tip pieces to merge smoothly between the TE which will be pinned to the board, and the LE which (due to the undercambered section) will be c3/16" off the board.

Is it best to glue the two tip pieces together as a seperate operation, let them set hard, then add them to the gap twixt LE & TE when the rest of the wing has been constructed????
On the Senator the same applies. I completed the wing tips leaving them a little oversize. Pinned them down flat and applied the trailing edge. The leading edge was then overlapped the tip piece after trimming for a close fit. Glue it all up and when the wing is removed from the board use small scraps to make good any gaps. Your best friends then are, 1) thin cardboard.
2) Glass-paper. Use the card to make a template of the entire wing half. Mark it carefully so you can align it and place it under the wing. (you have to invert the panel, of course). This will give you an accurate outline for trimming the tips to exact shape. Not only that but used on the second wing panel the template ensures complete symmetry. Then sand everything to shape and smooth and blend where necessary.
Many eons ago (when I was only middle-aged ) I read or was told "the difference between a good finish and an excellent one is sandpaper!) 'tis true!
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Old Jun 16, 2012, 03:02 PM
So I'M meant to be in control?
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Ilkley, West Yorkshire, UK
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About blinkin' time, Blink!

Well, things have been happening, albeit slowly. As I say to Lady Blink whenever she staggers in when I am doing some enforced decorating and demands to know why it isnt finished - the preparation is what takes the time, and every hour spent preparing saves two in wasted work.......at this point she usually utters something fairly unladylike and disappears to raid the cellar again.

I have now recut all the printwood parts from medium 3/32" sheet, and have cut new ribs from some 1/16" quarter grain sheet ends I had. I have also designed and drawn up my ruddered fin. This has also been altered so that it will be let into the tailplane and sandwiched between two ribs a la Gipsy. The AH (Louis Heath?) design merely had it glued atop some upper surface sheeting on the centre of the tailplane, which I felt was a weak point in a turnover. I have also opened up the holes in my bulkheads, saving well over a gramme. Even though I stated I wouldnt chase every gramme, I have purchased a cheap set of scales with 0.1g accuracy....

No cork yet from my Spanish friends, and with the amount of rain we have had (its hammering on the window as I type) by this afternoon I had started to run out of preparatory things with which to occupy myself. Digging around behind the Bentley in the garage, I found an old wardrobe shelf from the days when furniture was made of wood. A quick squint for flatness, and up into the loft with it. Time to actually build something!

An hour or so later something resembling a fin had been produced, and is currently drying. Tomorrow (if it's worked when I lift it from the board) I will cut the rudder free and do a little sanding. Most enjoyable!
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Old Jun 16, 2012, 03:12 PM
So I'M meant to be in control?
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Ilkley, West Yorkshire, UK
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Embarassing Photos Department

Found this in a box...... Given that by the age of 12 I wore glasses, this must have been taken when I was 11 or so, making it c1972. The Ajax had obviously been through a couple of seasons, as it sports the red fuz and blue panels on the wings that I thought made it look good . Note the warped tailplane, which induced an interesting tendency to roll......

I am holding a KK Minimoa (my first, built by Father - which flew. My second, built by me died very quickly without a reasonable flight). Bottom left is a KK Gemini, half built by elder brother, and completed by me with orange wings.

I apologise for the hair. The ironic thing is, now I have none!
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Last edited by Colonel Blink; Jun 18, 2012 at 04:06 AM.
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Old Jun 16, 2012, 03:52 PM
I like real wooden aeroplanes!
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South-west France
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Hey, looking good Colonel - the build that is, not the hair! Blimey, you are really young, nobbut a youth as we used to say in Yorkshire. Being older than you my embarrassing photos from long ago don't feature long hair, it wasn't fashionable then, mine was more of the minor public school/pseudo Adolf Hitler style, but I did have the dreaded moustache.....

Congratulations on having a KK Minimoa that FLEW, even if you didn't build it yourself. The longest mine ever managed above ground level was about 20 seconds.
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Old Jun 16, 2012, 04:42 PM
So I'M meant to be in control?
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Blimey, you are really young....
Well, as evidenced by everyone else's midmorning midweek posts, I'm probably one of the few who still have to work for a living........... Though having now passed the half century mark, I am finding that I have started to say 'eeeeyyyyooooff!!!' whenever I get out of bed.....

George................. were you once in the 70s band 'Sparks'???
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Old Jun 16, 2012, 04:45 PM
RFJ
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My KK Minimoa story. Spent the whole of the school summer holidays making one. Put it together to admire and set it down on the sofa. Left the room for five minutes and returned to find that my mother had sat on it Completely destroyed ( the Minimoa that is, not my mother)

Our relationship was never quite the same after that

Ray
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Old Jun 16, 2012, 05:04 PM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
Joined Nov 2008
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...returned to find that my mother had sat on it Completely destroyed .....
What is it with some women that they either can't see a model which is several feet wingtip to wingtip, or they do not equate the words 'balsawood and tissue' with any level of fragility? I'll admit that my mother (now residing in Perth WA - so watch out kkphantom!!) was great about that sort of thing; she always took care around my models, and feigned interest and admiration for anything her little soldier 'constructed'.

But your story does call to mind various tales.... Whilst building my Gipsy I wrote a piece about my aeromodelling youth..... if I find it and my scanner has OCR, I'll post it on my blog.
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Old Jun 16, 2012, 05:52 PM
I like real wooden aeroplanes!
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South-west France
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Originally Posted by Colonel Blink View Post

George................. were you once in the 70s band 'Sparks'???
Naw, by the seventies I was far too old to be in a band! The 'tash had been removed before I met my wife in 1966, something for which she has been eternally grateful!
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