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Old Jun 11, 2012, 11:43 PM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
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Originally Posted by kkphantom View Post
Carry on as you were Colonel, two bulkheads in the Gipsy as well.
Cheers Gary!

I respect and welcome all advice - especially when it comes from those whose experience and expertise is undeniable (and I am a little in awe of)!! But there will be times when I will consciously choose not to take it For me and for this build, I want to try and tread a fine line between not caring about the weight, and being fanatical about shaving off tenths of grammes. To get totally focussed upon weight reduction would kill some of the fun of the build; which is mainly a return to being a nine year old lad with his Dad at the kitchen table.

I know this Ajax will end up overweight, but it is not intended to be a competition model - as long as it can stay in the air all the time the motor is running, I'll be happy!!!
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Old Jun 12, 2012, 12:46 AM
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Australia, WA, Perth
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Originally Posted by Colonel Blink View Post
I know this Ajax will end up overweight, but it is not intended to be a competition model - as long as it can stay in the air all the time the motor is running, I'll be happy!!!
Exactly! So it won't climb as quickly as a lighter one, big deal! If you're happy with it that's all that matters.I build competition models too where every molecule matters but if you were building a model for competitions you wouldn't choose an Ajax!
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Old Jun 12, 2012, 04:10 AM
I like real wooden aeroplanes!
Sundancer's Avatar
South-west France
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Originally Posted by Colonel Blink View Post

I know this Ajax will end up overweight, but it is not intended to be a competition model - as long as it can stay in the air all the time the motor is running, I'll be happy!!!
To cheer you up Colonel, I was browsing some back issues of EFI (before it became Q&EFI) last evening and came across an Ajax built for electric R/C 12 or 13 years ago before we had the benefit of little brushless motors and lipo cells. It weighed 10 ounces, way more than I expect yours will finish up, and flew perfectly well. So just keep on trucking!
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Old Jun 12, 2012, 04:19 AM
*jj
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United Kingdom, Birmingham
Joined Jul 2008
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Originally Posted by Applehoney View Post
> just make the bulkheads out of a rectangle of 1/8" x 1/4" balsa strip.

Why bother with bulkheads? Useful for a novice, yes .... but not necessary to put together a box fuselage and merely added weight
Well, I doubt that the miniscule extra weight will do much for a model like the Ajax! And, personally, I find that this is simply the easiest way to make models, including Senators; you can produce them nice and straight and square without jigs and so on.
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Old Jun 12, 2012, 06:35 AM
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Well, I doubt that the miniscule extra weight will do much for a model like the Ajax! And, personally, I find that this is simply the easiest way to make models, including Senators; you can produce them nice and straight and square without jigs and so on.
True, and as these responses show, there are many ways to kill cats. No doubt we all have our preferred approaches. There is rarely a "correct" way to do anything or an "incorrect" way, just slightly different. I certainly don't intend anything I post here to be seen as critical of others, most of whom are far more experienced than I am. Just sharing ideas adds to the point of being here in the first place doesn't it? Let's see how others tackle things and occasionally we'll pick up on something that enhances our own builds. This has been the case for me as I have found inspiration and motivation that otherwise I'd have missed. Why am I building a Senator that I'll probably rarely get a chance to fly given the rotten windy, wet weather we get here? A "cookup" on the Small Flying Arts" forum, that's what prompted my Britkit entry. My model is not for free flight but for radio and will not have an undercarriage except for "posing" purposes. So it's not going to be a truly traditional model, but I have never enjoyed a build so much! It was seeing what others were doing that inspired me so I hope my posts will at least be interesting to you who look here. At least, they may give you all a laugh.
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Old Jun 12, 2012, 07:20 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
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Perfectly put, Bob! I agree entirely, and I'm happy for people to pile in with suggestions - I just wouldn't like anyone to be offended when I go my own sweet way to a terrible conclusion!!!

I must admit, your comments concerning the opportunity to fly a lightweight had crossed my mind as well - I think last year, there were only two evenings when I had the opportunity to go up the moor flying and it was calm enough that I thought it would be nice to put up a stick & tissue job..... But as you say, that's not the whole point of the exercise, is it?

Quote:
Originally Posted by Sundancer View Post
To cheer you up Colonel.....I came across an Ajax built for electric R/C 12 or 13 years ago before we had the benefit of little brushless motors and lipo cells. It weighed 10 ounces, way more than I expect yours will finish up, and flew perfectly well.
10oz? Blimey, that had eaten all the pies hadn't it!! That must have really needed to belt around the sky to stay aloft. I am loathe to have a target weight, as I believe to have a target requires some experience and knowledge - both of which I am sadly lacking. But I suppose I was hoping for somewhere in the region of half of that.

I would like to see a scan of that article if possible - it would be interesting to see things like rudder/fin proportion, and whether the chap used an added strip elevator or an elevator let into the tailplane outline.
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Old Jun 12, 2012, 07:31 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
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Oops sorry, forgot to mention I had a right relaxing lunchtime at my desk today - one of the bonusses of working for one division of the Corporation but having an office in a different division - if you ignore your phone and emails, you don't get disturbed!!

Just out of interest, based upon comments about kitwood, I weighed (on a balance only accurate to 1g) the printwood and the rib wood. When plonked into the quick Excel calculator I knocked up, this gave densities of:

Printwood c7.7 lb/cu ft
Rib wood c13.5 lb/cu ft

Now this is an area I know nothing about, so how do those compare to what is considered good or bad? My thoughts are that the printwood is OK but the ribs 'could be better'. But if they aren't in the hilarious 'totally hopeless' area, I'll still use them.
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Old Jun 12, 2012, 07:37 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
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Oh, and I fired an order off to BRC this morning as well.....and another to HK......
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Old Jun 12, 2012, 07:44 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
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Originally Posted by Colonel Blink View Post
Rib wood c13.5 lb/cu ft
My thoughts are that the printwood is OK but the ribs 'could be better'. But if they aren't in the hilarious 'totally hopeless' area, I'll still use them.
I just tried to gently release one of the die cut ribs with my scalpel blade........

Anyone need a floorboard???
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Old Jun 12, 2012, 07:53 AM
RFJ
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Balsa of 6 lb/ cu ft or less is generally considered "light"

Ray
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Old Jun 12, 2012, 09:53 AM
I like real wooden aeroplanes!
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South-west France
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Originally Posted by RFJ View Post
Balsa of 6 lb/ cu ft or less is generally considered "light"

Ray
Absolutely Ray - it could be also considered pretty b****y rare!! Back in the days when there were a few model shops and they used to stock, and sell, reasonable quanitities of balsa, I was in the habit of taking my pocket scales with me whenever I visited one, working my way through all the stock, especially the 1/16" sheet and buying anything reasonable on the spot. This got some old-fashioned looks from the other customers, but was much more efficient than waiting until you needed timber for a particular build. However, even in those days, 6 lb/cubic foot stuff was pretty thin on the ground and I was happy to settle for anything in the 8/10 pound area. I am therefore somewhat impressed with the orders I get here in France from Balsa Cabin, as in the three batches I have so far had, having specified "light" for my 1/16" sheet, it has all been between 7 and 10 lbs/cubic foot.

Colonel; sadly there are no details of the Ajax conversion I mentioned, it was in an "other people's models" item and just comprised a small photo and a brief description, wherein the weight was quoted. I'll measure the rudder and elevator areas on the Witch and let you know what they are as a % of the totals - but I can say now they don't need to be big. Personally I would build the elevator area into the exisiting tailplane outline, and you might also like to consider just making the elevator on one side only - this works fine on these type of models.

13 lbs cubic foot is heavy for the wing ribs, however the main requirement for ribs is to get quarter grain sheet for them - again Balsa Cabin score here in that you can order quarter grain 1/16" and i can confirm that that is exactly what you get. No help to you Colonel as you only need small quantities but a godsend to me, stuck in the model shopless wasteland of rural France!
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Old Jun 12, 2012, 12:25 PM
RFJ
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Too true George. I have a stash of 6lb and under sheet collected over 40 years but I'm very reluctant to use any knowing how difficult it would be to replace - crazy isn't it.

I also use Balsa Cabin and find their wood (and service) very good. Run by a very pleasant young lady whose name I have forgotten but perhaps a relative of Cliff Goater. SLEC also provide rather nice wood. I usually order a bundle from each every year.

Like the look of Sportster by the way. I considered it for a while but reckoned the fuselage shape was beyond me.

Ray
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Old Jun 12, 2012, 01:42 PM
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>perhaps a relative of Cliff Goater

Could this be the one and same Cliff Goater who was at a Colchester modelshop in the 70's and from whom I purchased several large engines for my then-collection?

'Saturn Models' comes to mind but may be confusing that with another source.
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Old Jun 12, 2012, 03:01 PM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
Joined Nov 2008
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Unfortunately my 'stash' of wood is mainly made up of offcuts and sheet ends of thicker stuff than I require for this build!!

Having spent all lunchtime cutting the above pictured parts from the 1/16" printwood from the Amerang kit, I notice that on the Albert Hatfull plan all those parts are in 3/32" sheet! I may just be cutting all those parts out again over the next few days.

The Amerang plan is at work at the moment, but there's a couple of things that aren't quite stacking up in my mind at the moment....
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Old Jun 13, 2012, 01:17 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
Joined Nov 2008
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Here we go.....

I have sort of decided to cut my own ribs - partly due to the hardness of the wood in the kit, partly because of some of the crushing during the die cutting process, and partly because I may put one or more upper spars in - probably 3/32" square. I remember my old Ajax had severe tissue sag between the ribs, and even at that tender age I realised that the aerofoil section would be somewhat compromised anywhere but at the ribs.... Additional spar(s) would also add strength to handle the extra payload of the batteries and radio and the additional aerodynamic forces due to being controlled, but for little weight penalty.

What I am not sure about is whether to add two upper spars at about 25% and 66% of chord, or one above the main 1/4" x 3/32" and add a shear web. Perhaps my learned friends have some thoughts???

The other thing is when I compared the die cut rib to the dotted outline on the Albert Hatfull plan, there was not a good match. 'Nay problem' sez I, 'There's a 'typical rib' shown on the Amerang plan...'. Even worse a match!! Anyone any suggestion which would be best - or anyone know what section Mr Hatfull would have most likely chosen? Then I could plot it out for myself........

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