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Author Topic: Aerographics Blackburn monoplane reduced to 1/20 scale  (Read 336 times)
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g_kandylakis
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« on: March 23, 2020, 01:50:30 PM »

not exactly a build log, as the model has been built 5-6 months ago, but it never hurts to post something ...

Last summer I decided I needed a CO2 model for a variety of reasons. I have long wanted to build the Blackburn monoplane, so I set out to find a kit or a plan. Much to my surprise I could find neither of the two.
A query to Pete Fardell was rewarded with a set of scans (thanked him then, happy to do it here again) so I was able to start working.

Having seen a built model in the magnificent garage of Richard Granger some years ago, I had forgotten how big the model was. So it was scaled to (yes...again...) 1/20 scale, suitable for a GM 63, handy for my flying halls and for my habits.

I wanted to keep it simple so I stuck to the plan as much as I could. It would not be meant for competition, mostly for fun flying and indoor exhibitions in Germany, to stir up some more interest in free flight. Eventually it ended up flying in competition in last year's IIFI, something I told myself I would never do  Grin. Just for the fun of it... Greatly surprised that it good highest "static" points...

Anyway, there is nothing spectacular about it, I only wanted to show my motor installation. Many members here already know I set up a group on facebook for CO2 motors. actually many are members there too...

I do not wish to post build logs there though, for me they seem to vanish after some years. A forum is much better for that, plus all topics are separate and easy to find in each category.  I 'll be posting a link there to here.

To the point now, my (bitter) experience has been that it is better to be able to completely remove the whole motor system out of a model, in order to go through it, in case of trouble. Even the tank and the filler nozzle. Jack Plane knows what I am talking about... This may include the need for removable panels held with magnets, a bit more complication and effort but well worth it in the end.

So an extra effort was made with the Blackburn in that direction and it has served me well, because, Murphy's law, after the first tests there was something wrong with the performance of the GM-63. This only allowed me to make one single decent flight in IIFI. More than 5 times I had to take the motor out and see what is wrong with it.

The problem was solved only a few weeks ago, a bad piston o-ring. It didn't help that I had tried many replacement o-rings, supposedly suitable for the 63. They were slightly too thick which prevented high throttle settings and gave only limited power but very loooong duration. Anyway, that is done, the model is waiting for better days to show its' potential...

Due to the configuration and the narrow triangle fuselage, in order to remove the insides, first the tank has to be removed, then everything is pulled out from the front. Opposite for putting in. A wooden holder screwed to the frame keeps the tank in place for flying.

The rest can be better said with the following pictures.

Just a heads up, there is no dummy engine and no pilot, YET. A big shame for me  Embarrassed

George
Attached files Thumbnail(s):
Aerographics Blackburn monoplane reduced to 1/20 scale
Aerographics Blackburn monoplane reduced to 1/20 scale
Aerographics Blackburn monoplane reduced to 1/20 scale
Aerographics Blackburn monoplane reduced to 1/20 scale
Aerographics Blackburn monoplane reduced to 1/20 scale
« Last Edit: March 23, 2020, 02:29:50 PM by g_kandylakis » Logged

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g_kandylakis
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« Reply #1 on: March 23, 2020, 01:55:33 PM »

current status.. not the best photography, I am afraid
Attached files Thumbnail(s):
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
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g_kandylakis
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« Reply #2 on: March 23, 2020, 01:57:01 PM »

...
Attached files Thumbnail(s):
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
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g_kandylakis
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« Reply #3 on: March 23, 2020, 02:01:21 PM »

And the one flight...

(wrong link but I am not changing it, see next message for the correct one...)
https://www.youtube.com/watch?v=tNNYeqeBlrk&list=PLN29opIuaZIWkw31Jl2xNcad8mZsvMFeQ&index=18

George
Attached files Thumbnail(s):
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
Re: Aerographics Blackburn monoplane reduced to 1/20 scale
« Last Edit: March 23, 2020, 02:13:56 PM by g_kandylakis » Logged

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Pete Fardell
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« Reply #4 on: March 23, 2020, 02:10:07 PM »

Really nice, George. Soooo much tidier than mine! Remind me to never stand them next to each other.
(You might want to edit the flight link though as the Blackburn in it looks an awful lot like a DH Beaver and you seem to have morphed into John Bowerman.)
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g_kandylakis
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« Reply #5 on: March 23, 2020, 02:13:11 PM »

why not, his model flies much better than mine and he looks more respectful than I do  Grin

Here is the correct link, one video earlier...

https://www.youtube.com/watch?v=aV1f7pPijSo&list=PLN29opIuaZIWkw31Jl2xNcad8mZsvMFeQ&index=17
« Last Edit: March 23, 2020, 02:31:57 PM by g_kandylakis » Logged

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billdennis747
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« Reply #6 on: March 23, 2020, 02:28:49 PM »

Having seen a build model in the magnificent garage of Richard Granger some years ago,
George
Yes, a garage containing the full size Granger Archaeopteryx, Stanley Steam Car, numerous pyrotechnics, vintage motorbike etc etc and every model Richard has ever made!
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g_kandylakis
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« Reply #7 on: March 23, 2020, 02:31:25 PM »

hence "magnificent"...  Smiley

no to mention the treat of being guided in it by Richard himself...
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billdennis747
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« Reply #8 on: March 23, 2020, 02:34:53 PM »

Did you go for a steam ride?
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g_kandylakis
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« Reply #9 on: March 23, 2020, 02:39:22 PM »

no  Cry

Only briefly there for the indoor Nats, plus at one time it was out of commission because of a leak. Another feature of the garage, the many opened up cars, bikes etc...

I really need to double check for errors before I post  Embarrassed
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Jack Plane
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« Reply #10 on: March 23, 2020, 03:39:21 PM »


To the point now, my (bitter) experience has been that it is better to be able to completely remove the whole motor system out of a model, in order to go through it, in case of trouble. Even the tank and the filler nozzle. Jack Plane knows what I am talking about... This may include the need for removable panels held with magnets, a bit more complication and effort but well worth it in the end.

So an extra effort was made with the Blackburn in that direction and it has served me well, because, Murphy's law, after the first tests there was something wrong with the performance of the GM-63. This only allowed me to make one single decent flight in IIFI. More than 5 times I had to take the motor out and see what is wrong with it.

The problem was solved only a few weeks ago, a bad piston o-ring. It didn't help that I had tried many replacement o-rings, supposedly suitable for the 63. They were slightly too thick which prevented high throttle settings and gave only limited power but very loooong duration. Anyway, that is done, the model is waiting for better days to show its' potential...

Due to the configuration and the narrow triangle fuselage, in order to remove the insides, first the tank has to be removed, then everything is pulled out from the front. Opposite for putting in. A wooden holder screwed to the frame keeps the tank in place for flying.


Very interesting George.  I hope I'm not teaching grandmother to suck eggs and not suggesting the O-ring wasn't your main culprit.

However, for what its worth, on my GM63-BB powered Camel the hideous leakage problem was eventually traced down to the fact that I didn't originally have enough length of straight pipework exiting the cylinder head before the spiralled piping - so that when under the vibration of running there wasn't enough 'give' between the two, and this 'rigidity' resulted in massive leaking.

Looking at your photos, I wonder if you might have a similar issue?
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g_kandylakis
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« Reply #11 on: March 23, 2020, 04:05:02 PM »

Ok Jon, to begin with, I am certainly not a grandmother... Grin

Second, I am always open for discussion, so have no fear of me reacting badly Angry ( Grin)

Third, and now more seriously, I do not think it was the same thing. I did not have any leaks at all, only reduced maximum power. When screwing the cylinder in for a little more RPM the motor would somehow choke. The Czechs at IIFI suggested insufficient lubrication, it didn'y work...

I had replacement O-rings o.d./i.d./thickness 4,0/2,5/0,75, supposedly suitable, so I changed 2-3, no success. Then I switched pistons from a new engine. Perfect power... So I checked the o-ring only to find it was 0,65mm thick and slightly smaller in i.d. which forced them to expand slightly when in the piston.

So I took one of my replacement o-rings, wet sanded the thickness to 0,65mm and filled the inner diameter a bit bigger to 2.8mm and got again trouble free operation at full power...

As for rigidity, you are right, but in the Blackburn there is plenty of freedom in the pipework so I feel safe in that respect.

Your name mentioned was just for the fact of having accessibility when there is something wrong  Wink

Anyway, back to the Weick build ( Roll Eyes Roll Eyes Roll Eyes yes, started cutting wood)

George
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Jack Plane
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« Reply #12 on: March 23, 2020, 05:25:50 PM »


Your name mentioned was just for the fact of having accessibility when there is something wrong  Wink


Ah yes...  I've progressively learnt to introduce flexibility and accessibility into my entire life on the basis (Murphy) that there will always be something wrong!  Shocked  Wink

Lovely build, look forward to seeing the completed article - engine, pilot and all.
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« Reply #13 on: March 23, 2020, 08:07:31 PM »

George,

You're Blackburn looks superb. You make a very nice job of your models.
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« Reply #14 on: March 24, 2020, 02:13:37 PM »

George,

I really enjoy your posts of such well made models. Would you mind telling us your covering technique? What paste, tissue, dope and paint you used to such good effect?

Tim
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« Reply #15 on: March 25, 2020, 12:17:50 PM »

Hi Tim, thanks...

Gladly, there is no major secret behind it... Actually everything known more or less.

First of all, I like the structure to be completely smooth, so plenty of sandpaper with fine grain to make sure everything is even and smooth. This is a very imortant factor foe the tissue to "sit" properly.

I usually build my models with thick dope as glue ( Huh Huh Huh, yes...). This has the advantage that it sands beautifully, the same as balsa, so a smooth result at joints as well.

I prefer almost exclusively the "healthy" method of dope and thinners. The only time I did thinned white glue was with prepainted tissue where the thinner would dissolve the enamel painted lozenges (Albatros D.III, Fokker D.VII)

One coat of thick dope, evenly applied with a wood piece line bamboo as a tool, then let it dry for a couple of minutes. Maybe a second, for undercambered ribs or whatever... Wingtips, anything stubborn...
I glue the tisue to all members, ribs etc... not just outlines. rellevant or not, I do not know, this is how I like it.

Tissue without any wringles, mostly esaki, cut slightly oversize, laid stress free on the part to be covered.

Then thinners with a thin paintbrush, section by section. Once I apply thinner, I immediately press lightly with a piece of sheet balsa, rigid for plane surfaces, flexible for ribs, to press the tissue to the wood until the thinner evaporates. 5-10 seconds usually.

Then next section...

Wing of course differently, first middle of all ribs etc...



As for material used, simle nitrate dope and suitable thinner, name CLOU, from Germany.

https://www.ebay.de/itm/362607030632

Edges get extra dope treatment, always overlapping tissue.



Shrinking, nothing special, tap water, in delicate cases pre-shrinking.

Doping, same dope as above 50% thinner, mostly two coats, depends on the viscosity, the speed of applying, the extra weight... With paintbrush.



Paint, depends on the model or the color. Earlier enamels, mostly Humbrol or Testors Modelmasters (do they still exist?), more recently acrylics, an italian brand "Misterkit", specialising in WW1 shades, some suited to pioneer aircraft

Blackburn paint
https://www.misterkit.com/product/16880869/german-clear-doped-linen

Avro F paint
https://www.misterkit.com/product/16880882/german-naval-clear-doped-linen

For metal panels, Alclad 2 lacquers. The Blackburn was a flop in that respect. I used dull aluminium first, which came out, wait for it: dull...

After Nijmegen I removed it with thinner and re-doped and repainted with glossy. Much glossier now, like the original. Of course it also highlights the various doping imperfections... Good enough for Kit scale, or so I say to myself.

Well, that is all, I guess. Nothing unusual...

Feel free to ask any additional info you might need.

George
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« Reply #16 on: March 25, 2020, 01:35:47 PM »

Goerge,

Thanks for the detailed reply and paint links. You seem to use very much the classic methods. I have been using the translate function to look at the Czech aeromodelling forum and acylic varnish seems to be a popular replacement for dope. I note that some prepaint the structure prior to covering which reduces overal amount of paint required.

Tim
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