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Ask 18 1/4 scale glider from Cliff Charlesworth plans


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Hi everyone, I am going to be building the 1/4 scale ASK 18 scale glider form the Cliff Charlesworth plans. It's a relly nice looking model. I have had the plans for a few years now but never got the impetus to start building it up until now. There seem to be quite a few parts to cut out and there is a supplier called
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Stuart, I've built one of these and enjoyed the job. Because the main spar divides the ribs I took the trouble to cut a foam bed which profiled the underside of the wing and then having marked out all the rib positions etc built the wing upon this. It ensured that the angles of the ribs to the main spar were accurate. If you study the plan you will see what I mean. Maybe it was not necessary to take this step but I felt that it made for a true wing.
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Hi Barrie and Tom, thanks for your replies, been having trouble posting so switched to Firefox!. Lovely cockpit. Yeah I was trying to say that Key Publishing Ltd http://shop.keypublishing.com/acatalog/Online_Catalogue__ASK_18_1776.html do a K18 cut parts set for 130 pounds, plus 9.50 p and p, which seems alot, but wood is getting more expensive these days! Have spent 100 pounds on wood for my 10 ft Zogling!
 
I emailed the company to see what the parts list consisted of and got the following response:
 
Please find a reply from the company that supply the cut parts.

As a general description, all Parts Set include only the laser cut balsa and
plywood parts and no plan or stripwood/covering.

For example, the ASK 18 Parts Set includes, fuselage keel parts, bulkheads,
formers, cockpit frames, plus smaller items such as gussets. It includes
wing ribs, tip shapes for fin and rudder, fin and tailplane ribs, tailplane
spars, rudder post, air-brakes (in some cases). All these parts are shaped
and therefore the parts sets save modelers a lot of time. All the other
parts, such as stripwood and covering are items bought off the shelf at
model shops.

Edited By Stuart Eggerton on 10/10/2011 20:03:13

Edited By Stuart Eggerton on 10/10/2011 20:03:48

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Well, Stuart if you have the time, cut the parts yourself - much cheaper - but if time is money................
 
You will use quite a fair bit of 1/64th ply for covering parts of the fuz., wings, fin etc That is expensive stuff and will not be included in the parts set anyway. I personally buy my wood from SLEC. There is a choice of grade and their quality is first class, although you probably know this already. The '18' will cost a bit but you will find that the finished model will be worth the time and expense.
 
Do your plans include diagrams for the airbrakes ( in my set these were separate) ?
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Yeah in studying the plans there is lots of wood required!. I checked out the SLEC site, and it is very good and has some sizes that the balsa cabin don't have but does seem to be a bit more expensive?. My plans do have a simple diagram for the airbrakes in plan view. It shows the dimensions (250 mm long, top and bottom) but no section shown. See pic below of plan.
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  • 2 weeks later...
Hi Barrie, many thanks for sending me a copy of the airbrake details for the K18. I am looking at my plan and there is some text missing from the left hand side , it says, aluminium dihedral plates and then 15 inches, but I can't read the remainder of the text as it looks like there was a problem when the plans were copied. Does anyone know the full instruction? Pic is below.
 


Edited By Stuart Eggerton on 22/10/2011 22:06:32

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  • 2 weeks later...
I have contacted the people I got the plan from to see if they can shed any light on the missing text! I ordered a set of ply parts for the K18 by Cliff Charlesworth and didn't realise my plan was from M Charlesworth, but all the ply parts seem to tally with my plan, so I am happy about that!. Barrie Dav's plans (i.e original Cliff Charlesworth plans) do differ from mine a bit but a K18 is a K18!.
I have a 1/4 scale pilot on order and have also received a nice canopy!
 
I am cracking on with the 10ft wingspan Zogling for a bit and will dip into doing some stuff for the K18 soon. There seem to be too many projects and too little time lol, it's time to retire I think!
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I have received the ply and balsa parts from Key publishing for the K18 1/4 scale glider by Cliff Charlesworth.
 
Ply fuz parts below
Wing centre section ply parts below

Fuz ply parts below
Ply wing and airbrake parts below

Rib noses, triangular balsa gussets and ply fuz keel below

pre-cut fin / tailplane balsa templates below

pre-cut balsa wing rib parts below

Saves a lot of cutting out lol!
 
 
 
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  • 4 months later...

Hi Steve, yes that's right the model does use a full depth spar so I will have to cut out of each rib an equivalent amount of wood equal to the width of the spar, which will be tricky.

I will end up with each rib in two piecies, in front of and behind the spar so must label them as I go.!

Alternatively, some people have simply notched the ribs and put a spar top and bottom and added the side of the spar by putting shear webbing in effect between the ribs.

I would like to build complete the spar in one section as shown on the plan. You either do this and have to cut all the ribs in to two, or you notch the ribs and have to cut all the shear webbing between the ribs which you wouldn't have to do with option 1, it's a catch 22.

It would have been nice if the parts kit I purchased had the ribs cut into the correct sections but hey ho! smiley

Edited By Stuart Eggerton on 20/03/2012 18:06:43

Edited By Stuart Eggerton on 20/03/2012 18:09:39

Edited By Stuart Eggerton on 20/03/2012 18:10:54

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  • 2 weeks later...

I have been doing some work on the ASK-18 glider. Step 1 was to make the female formers for the male formers to fit into. These were made from 1/8th lite ply.

Typical female former is shown above.

Above is shown a set of female and male formers.

I then made a jig by marking former positions from the plan onto a plywood base. Making sure these positions are 90 degrees to the fusulage centre line.

Then glued the female formers to the base of the jig, ensuring they are square in both axes.

You can see the female formers in the above photo, and I used triangular gussets to ensure verticality of the female formers. The male formers were dry fitted in place, as were the centre section parts. I needed to adjust one of the female formers as it was slightly out.

 

Above photos shows the bottom keel and the top keel strips (both spruce)

The formers are 1/8th spruce.

Front keel top and bottom added and butt up to the wheel pant and rear keel parts.

 

Edited By Stuart Eggerton on 30/03/2012 22:24:12

Edited By Stuart Eggerton on 30/03/2012 22:28:15

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Hi.

Some time ago I had problems when I started building 1/4 scale, I did not know where to start. It was Cliff who put me right with his book.

Scale Model Gliders by Cliff Charlsworth. £14.95 from Traplet Publications.

Hope this is of use, I look forward to seeing the finished model.

Happy flying

David

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Hi David, thanks for your suggestion, I actually got this book at Christmas! it's very useful and packed with lots of info, Cliff used to work in the full size aviation industry so understood full size construction methods and I think his talent was then to be able to produce models that were strong and yet light and someohow mirrored the full size using different materials. smiley

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Hi everyone, I need to buy some servos for the airbrakes and the ailerons, ready for when I start to make the wings.

I have decided to mount both sets of servos in the wings as it's easier than control snakes from the fuselage. The airbrake servo's can be any size as the rib is up to 40mm deep at the point where the servo is required. Does anyone have any suggestions as to the correct size of servo to use for the airbrakes? i.e. minimum torque? They will need to operate top and bottom opening Schempp Hirth type airbrakes which are about 13 inches long and about an inch high (top and bottom). Should create lots of drag for those steep approaches

Similarly for the ailerons, I need servos to operate these too. The ailerons are some 24 inches long by about 2 inches wide, the trouble is the rib where the control horn is situated is only 21mm thick at it's highest point and I would need to install the servo behind the spar where the rib begins to narrow. Any suggestions as to the minimum size of servo for the ailerons? If I need servos that will not fit into the gap I will have to install them further towards the root where the ribs become thicker and add some bell cranks to take the movement 90 degrees around the corner.

 

The ship will be 4 metres in wingspan and about 8 pounds flying weight (I am guessing the weight). Want the servos to be up to the job.

All suggestions are welcome

Edited By Stuart Eggerton on 09/04/2012 21:48:47

Edited By Stuart Eggerton on 09/04/2012 21:49:52

Edited By Stuart Eggerton on 09/04/2012 21:51:03

Edited By Stuart Eggerton on 09/04/2012 21:51:49

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