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Ask 18 1/4 scale glider from Cliff Charlesworth plans

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Stuart Eggerton14/08/2012 23:37:26
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352 forum posts
302 photos

Centre section from a different angle

The parts put together

Barrie Dav 215/08/2012 07:52:38
1012 forum posts
14 photos

Progress Stuart. These things take a lot of time to build don't they. They look good before covering.

What covering are you going to use by the way?

Former Member15/08/2012 08:05:06

[This posting has been removed]

Rich too15/08/2012 08:10:58
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3060 forum posts
1070 photos

Superb write up!

Rich

Stuart Eggerton15/08/2012 11:13:05
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352 forum posts
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Hi Barrie, yes they do take a long time to build! sometimes seems like it will never end. Yes it's a shame to cover them as the bare wood structure is so aesthetically pleasing and a work of art. I intend to cover the entire model in Solartex, I have bought some already. The predominant colour will be white with a red rudder and red trims along the fuselage and a red nose in solartex, oh and red wing tips, so should look nice

Hi Andrew, yes the laser kits part did save me lots of time cutting out ply and ribs etc. If you get the chance to finish the model I am sure that it will be worth the effort

Edited By Stuart Eggerton on 15/08/2012 11:13:28

Stuart Eggerton15/08/2012 12:32:40
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352 forum posts
302 photos

Thanks Rich for your kind comment

mark etherington27/08/2012 07:51:35
32 forum posts
2 photos

Hi Stuart that's really good but it's such a shame to cover it !!!!!! smile d

Alan Cantwell27/08/2012 08:39:56
3039 forum posts

Been looking in for a while, lovely build, Stuart, could you please give me the dimensions of your joiner blade for the wings, i have picked up the same glider and have no joiner blade, mine seems an odd size, gliders company can only supply a blade 1mm differant in height than i need thickness is ok, but its the height that is wrong, ta much

Stuart Eggerton15/09/2012 21:49:46
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352 forum posts
302 photos

Hi Mark, yeah it's a lovely structure! I am going to cover it in white solartex.

Alan I sent you a pm regarding the joiner blade, did you recieve it OK?

Stuart Eggerton15/09/2012 22:00:34
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352 forum posts
302 photos

Progress on the K18 is steady, I was hoping to get it ready before now but that time frame was unrealistic. So will just steadily plod along with it. wink I have had all sorts of trouble with the Schemp Hirth air-brakes (top and bottom acting) as they kept binding, so a central pivot re-design has been the order of the day, with good results. Servos for the air-brakes have been installed and the 1/16th sheeting around the air-brake box too. The fuselage has been predominantly sheeted in 1/16th balsa forward of former G. I have left out a few panels in the nose to allow for the installation of an electric motor, will have a spinner and folding prop. Only problem could be the situation of the lipo pack as these is very little distance from the rear of the motor to the instrument panel.

The tail feathers have been shaped and covered already, rudder is red, the rest is white. Just need to glue the hinges for the elevator. The hold down bolts are nylon.

I need to do some work around the wing roots of the fuselage and blend them with the wing itself and make a hatch for the fuselage centre section.

I have made a canopy, it all went well and the canopy fits well, so I am pleased as I have never worked with a large plastic blown canopy before. The front and rear hoops for the canopy were made from laminations of plywood, soaked in hot water and bent round formers. That canopy glue stuff is great, first time I have used that too.

Pictures will be posted in due course smiley

Stuart Eggerton20/10/2012 21:54:21
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352 forum posts
302 photos

Hi everyone, progress with the ASK-18 is going very well.

I managed to get the airbrakes sorted out at last! smiley You can see one of the servos which actuates one of the airbrakes in the picture below. The servo wires are run through the wing ribs.

 

 

The fuselage has mainly been sheeted as per the plan with 1/16th thick sheet balsa wood. Note the sheeting stops at the former to the rear of the wing.


 

Another view showing the cockpit area and the sheeting.


 

Below is a picture of the tailplane mounting system, two nylon bolts are used to secure the tailplane to the fuselage. One bolt passes straight through the tailplane and the other first passes through a plate glued to the rear of the fin. This allows the whole tail to be removed if required. The rudder sits on a pintle. Both nylon bolts have metal threaded bolts on the end of them.

You can see the blue elevator snake and the rudder will be moved using a closed loop wire system.

 

 

The canopy was more straight forward than I anticipated, you can see the original blown plastic canopy below.

I made a canopy frame and also some locating pieces for locking the canopy out of some aluminium tube. The canopy frame was painted grey.

You can see the access hatch for the nylon bolts here, held on by two screws. It has a slot in it to allow the pull pull cable to bass back and forth. You can see the fin locating tube as well, note tail surfaces have been covered in Solartex

 

A nice seat was made for the pilot to enjoy his flights in! smileyI painted it grey and the straps were from an old pair of binoculars! wink

I used some aluminium tube to try and replicate the original aluminium tubular structure of the cockpit and painted the cockpit grey. Notice the battery platform near the nose, this will hopefully house a 4 cell squat shaped lipo!

 

 

 

Some pictures I took of the model rigged up

 

 

Edited By Stuart Egge

Stuart Eggerton20/10/2012 22:04:42
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352 forum posts
302 photos

The top of the fuselage has been sheeted too, and there will be a removable hatch which will cover the gap between the wings, and allow access to the servo wires and the wing band.

The picture below is one I took just now

I have changed the front former to give some side and down thrust for the motor and glued a ply doubler to the front to strengthen things up. The rear of the fuselage has also been covered.

The next stage is to fit the motor and do some watt testing with various props. The weight of the model is expected to be in the 8lb - 9lb range. I am going to get the motor installed and fly the model before covering the nose sections or the remainder of the fuselage as if any thrust line adjustments need to occur this could be tricky if the fuselage is sheeted. You can see the top hatch in the photo. I have read that the correct CG for this model is exactly 1/3 wing chord from the leading edge at the root. A 4 cell battery is expected to weigh about a pound.

So I am getting excited to see how well it flies. I also need to set up the correct amount of movement on the control surfaces.

Once I have proved the model does fly then I will concentrate on finishing off all the nice details

Radge20/10/2012 23:23:03
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322 forum posts
48 photos

How absolutely fantastic Stuart! Amazing to watch your build progress and develop into, what is for me, a treasured aircraft. I flew a full size ASK18 registration R49 back in the 80's and it was in that glider I achieved my Silver gliding award. winch launched I flew from RAF Marham to RAF Coltishall in 2 hours 45 mins. (See log entry 292 and qualifying baragraph trace) I cannot wait to see your '18 flying.

ask18 silver019.jpg

Stuart Eggerton21/10/2012 08:19:49
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352 forum posts
302 photos

Hi Radge thanks for the lovely comments. Yes the K18 is a very nice aircraft and when I was looking for a scale glider to model this one just looked right. The high aspect ratio and the elegant lines are to me what a glider is all about.

Well done on achieving your silver award back then, I seem to remember the summer of 1988 was quite good weather wise for soaring? 1989 was especially good, as I had just left school in the summer and remember doing a 51 minute flight with my Flair Sunrise glider

I think I have found a picture of the glider you flew below? R49 and R48 is hiding behind R49.

I got the motor istalled last night, so over the next few days some power testing and setting up the controls are the order of the day.smiley

Radge21/10/2012 09:02:11
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322 forum posts
48 photos

Awwe Stuart, thank you so much for this photo. She's still looking good but was in your colour scheme with little RAF roundels on the wings when I flew her. smiley The weathers quite settled for a maiden over the next day or so but don't rush it as you've done an amazing job so far. I can't wait!

Barrie Dav 221/10/2012 09:06:02
1012 forum posts
14 photos

Well done Stuart. It's been a long haul but I'm sure that you will think it worthwhile once you get it into the air. The full-sized '18' was a sweet aircraft to fly and although I've not flown my model, the fields in my region are too small for a model of this size and we have no slopes, I understand that the performance of the Charlesworth design is guaranteed to please.

Years ago together with a friend I used to own a K6 and have thought about building a quarter scale model of this too but I am retired and I just do not have the time!! True!!

Stuart Eggerton22/10/2012 17:41:43
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352 forum posts
302 photos

Hi Barrie, yes it's been a hard slog to get it built, I don't think I will be building anything else for a while lol!

I am a bit nervous about the first flight, i.e, the speed that we need to hand launch it at and also our landing area is a bit on the small side, it's surrounded by obstructions like lamp posts and other stuff, but have flown there a few years so I will need full concentration!. I hope the power train allows me to climb out clear of any obstructions before doing any sort of sharp bank and then once at height test out the stall etc. Did your full size show any tendency to drop a wing? Obviously if on or near the stall, but I have heard it does have nice flight behaviour. There is plenty of wash out built into the wings. 3/8 inch at the tip.

Regarding the K-A6, below is a magnificent video of a half scale model! enjoy.smiley

Edited By Stuart Eggerton on 22/10/2012 17:42:29

Edited By Stuart Eggerton on 22/10/2012 17:43:16

Martin Harris22/10/2012 17:58:48
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9343 forum posts
252 photos

Seeing your logbook brings back memories, Radge. Mine went missing somewhwre a few years ago and I've regretted not keeping it under lock and key ever since!

I remember being quite chuffed to see Cliff' Charlesworth's prototype on the cover of (I think) RCM&E - one of the last issues I bought when full size gliding took over from modelling in the late 70s. It was modelled on "174" which was the K18 that I did my first solo in at Dunstable (in those days, the K13s were deemed too valuable for first solos to be done in them!)

There was a fair bit of washout on the full size (the wingtips tended to start to noticeably tuck under at speeds approaching VNE) but it was a very well mannered glider that would spin if made to but was otherwise quite docile. The airbrakes should allow good approach control if they're anywhere like the full size - which I imagine they will be.

Steve Sheppard22/10/2012 18:03:06
21 forum posts
2 photos

Hi Stuart

All looking good

I bottled out on building one and bought a ready to fly electric 1/4 scale T61 (Cliff Charlesworth plan).Even though I new the model had flown I was nervous about the length of take off etc. The model is powered by a brushless outrunner on 6 cells turning a 14*10 prop at 1200 wattts.I opened the throttle slowly and to my suprise the model was airbourne in about 15m at about 2/3rds throttle.The landing run is also short and safe using the spoilers and a touch of throttle.The biggest problem I have is judging the distance as the model is over twice the size of models I usually fly.

Unfortunately I damaged the cowl and landing wheel after a motor problem(loose screws on the motor shaft) on take off resulted in a heavy arrival after a stall from around 3m. I have taken the opportunity to refit the model and install a scale cockpit.Have you found a source for a reasonably priced 1/4 scale pilot?

Steve

Stuart Eggerton22/10/2012 21:19:14
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352 forum posts
302 photos

Hi Martin thanks for the vote of confidence re the docile flight characteristics, and thanks for sharing your story on the T61 Steve. I have a 600kv motor running on a 4 cell and producing 630watts, so reckon it has enough power for test flights as the weight will be around the 8.5lb mark. I have added a fixed prop for flight testing 14 x 6 and see how it performs, the motor etc is drawing around 45 amps at WOT, so looking good, as esc is rated at 60amps. I do need a separate BEC eventually.

I have this evening added a former to stop the battery going too far forwards and also a shelf inside the nose to velcro the esc to.smiley

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