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martynk

Cheshire Cat 100S-E

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martynk

Progress is slow but steady

All 6 Panels have been assembled = i.e. ribs and LE and TE and Gussets assembled.

Following the same methods that I used on the Bubble Dancer,

The outer panels were assembled as one unit then sawn apart after the glue dried.

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The wing tip has been laminated around a 12mm ply former and one layer of .007" carbon layered in

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TE sanded to shape.

My hinged building board is back in use. 18.6 degrees of tilt and the first of the 2 outer panels have been glued together

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On the inner panels, the lower carbon spar cap has been glued into place and the 9mm soft balsa webs glued and genty weighted down while the slow set epxy set - which in the heat last week was actually quite quick..

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and as you can see the wing joiner blocks are also in place. Basically, the blocks were assembled and the centre panels were joined correctly aligned and the whole lot epoxied and left to harden.

One mistake I made in the planning. I had some small ovals cut to get the spoiler servo leads through the ribs - which were just a little too close when I came to cut the 12mm joiner block slot - so I have a little bit of post operative surgery to perform to tidy this up. Nothing life threatening though. Also been a bit clumsy with the sander :blush:

 

 

More to come..

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martynk

A bit more progress.

 

All the spars have been fitted and the inner panels bound with Kevlar.

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Lower spar caps fitted first followed by the thick balsa 'spar' and then the upper spar caps

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The tilting building board used to set the dihedral angle

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Short 0.007" carbon strips fitted over the dihedral joints - top and bottom

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Bound with Kevlar and resined (if that is a word - if not it needs to be)

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And a bare bones shot of the wing.

 

The lengthy process has been adding the D box sheeting and compressing it down. I have used Gorilla glue for the Carbon to balsa joint - PVA everywhere else

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Fitting one piece a day = 12 days work (nearly)

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Adding the inlaid sheeting at the root..

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and the dihedral break. I have got a bit or remedial work to do on the trailing edge - I dinged it :blush:

Currently sanding down the LE  but I have some more inlaid sheeting to fit yet as well. 

One problem I have run into is that there is insufficient space to fit the servos for the spoilers in the wing so will need to fit into the fuselage and link using a bellcrank. Shouldn't be too difficult a problem to resolve - hopefully.

More to come

 

 

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Whitmore

That's really nice! What sort of weight are you at?

Jon

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martynk

Thanks Jon

Too frightened to weigh it :)

Seriously though I intended to weigh every component to calculate the pitch and roll moments but simply forgot - got too engrossed in the build. It actually feels quite light at the moment, I'll weigh it later and report back.

 

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martynk

Weights so far:

left wing 136g

right wing 147g

boom pushrods tailplane and fin 92g

wing joiner 30g

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martynk

Some more progress.

The balsa D boxes have been completed and the LE and TE (apart from a polish before I cover) have now been sanded to shape. A little more sanding to do in one or two places as well

The spoilers were rather tricky. I was planning on fitting servos in the wing but there simply wasn't sufficient space. Quite a lot of head scratching and playing with bent bits of wire and I eventually settled on using bell-cranks driven from a single servo that will be fitted in the fuselage.

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These are mounted on 3mm beech blocks and trimmed and drilled to fit - rather than optimal. I must think this through better next time.

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Cut down nylon horns embedded into the spoiler and then supported with a small piece of 2mm lite ply - using epoxy as an adhesive and a bent piece of stainless steel wire as a linkage arm. Pushrod snakes will run down the holes that had been cut for the servo leads.

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Spoilers go up to 80 degrees 

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 and lay flat went told to do so

With that out of the way, I have started work on the fuselage. Repeating the style of construction used on the Bubble Dancer - Lite ply sides but with the wing joiner through the fuselage. The plan is to build in some 12mm balsa fairings to the wing join to try and reduce induced drag a little. The challenge is getting all the holes drilled accurately

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Balsa triangle stock is used in the corners and it will all be sanded smooth and rounded when done. The 12mm fairing pieces have yet to be added.

Getting near the end now. Hopefully I will get this model completed in the next few weeks before the summer disappears

More to come

 

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martynk

A bit of progress over the weekend. My daughter gets married in 12 days time and I have been tasked with doing a few 'tidy the house' exercises like 'paint the garage door' - which turned into 'paint the front of the house'... It needed doing..

So , in the spare moments I have made a bit more progress

On the fuselage, the tricky bit is getting the wing fairings in place and aligned so that the wing is at the correct AOI (1.5 degrees) and that both halves are aligned. The AOI was easy, the datum measured and then Tan alpha x Chord gives me the chord line displacement and it was simply measured and drawn onto the fuselage side.

DSCN3056.JPG

Note that it took me two attempts to get the datum :blush:

The main joiner support is a former made from Basswood with the 8mm hole drilled through. With the joiner in place the fairings are rotated to the correct angle. The rear locating pins are drilled before the fairings are glued, one being a drilling template for the other.

DSCN3054.JPG

This shows the layout of the beefy basswood central former and the rear former, drilled to carry the boom.

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With the fairings aligned and drilled through, the fuselage floor has been added and the nose ring. 5 degree of downthrust will hopefully be enough

There are two small balsa cheeks behind the nose ring to square the circle or some other similar metaphor.

A dry assembly was in order..

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and

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No photos on how I attached the boom. The front of the boom is a nice sliding fit in the rear former. This and contact area around the rear of the pod was liberally glued up with 24 hour epoxy and the rear end clamped so that the ply sides pulled around the boom. I am quite pleased with this, I'll take some photos later

Last thing, last night I added a fairly liberal dose of finishing epoxy and micro balloons. By this morning, it had hardened and the majority has subsequently been sanded off.

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Photos to follow.

Front hatch is under construction, servos to be fitted next then spoiler push rods and other hardware bits should arrive in the next day or so. A 12x6 prop has already arrived from Gliders

 

More to come..

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martynk

More progress in the past few days

DSCN3065.JPG

Rudder and Elevator servos fitted. These are aligned at 45 degrees withe servo arm shafts aligned down the centre line so that I can get a nice straight run to the snakes yet still make the servos easily accessible

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Hatches have been formed. The front is laminated from 2 pieces of 3mm balsa (grain crosswise) over a 1/32 ply base, the rear is planked from 6mm balsa with each edge slightly chamfered to get the curve, Again - on a 1/32 ply base

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Quite pleased with those... :)

Motor and spinner have arrived.

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A bit dusty, but the motor is fastened to a 1/16 Glass Fibre plate. The normal cruciform mount supplied with these things is epoxied (and trimmed) to the front of the plate to add a little extra stiffness. The plate needs a little more reinforcement around the edge yet. I'll layer in a couple of pieces of G/F cloth

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The pointy bit - not too bad, needs a tiny bit off the lower fuselage

Finally, last night, I fitted the mounting blocks for the Spoiler servo and gave the fuselage a first coat of varnish. I was going to paint the fairings but the cream colour looks nice with the natural wood so I am going to leave them

DSCN3072.JPG

More to come.

 

 

 

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martynk

A bit more progress but not many progress piccies - sorry

Basically, its covered.

DSCN3073.JPG 

 

It has a Logo :)

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On the ground -  I think its a bit OTT on colours but its distinctive

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The hatches seem to fit nicely - just one screw to hold the rear cover and a magnet on the front

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It weighs this much with LiPo, and seperate flight battery.. A little bit heavier than I hoped - I was hoping for less than 1Kg - it doesn't actually feel that heavy. I'll recheck it, I've just noticed the lock symbol

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Not happy with the Spoiler mechanism, its fiddly to get the arms through the slots in the fus, but its very positive when its working

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Finally, a shot underneath to the wing fairings

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So - to summarise - there is a bit of tweaking to do. 

CoG needs doing - at the moment, ESC and batteries are just loaded in the front compartment

Spoilers need a bit of fettling

Trimming

- not this weekend though, my daughter gets married on Saturday but perhaps one evening next week.

Fingers crossed and all that

Not much more to come - holiday in 3 weeks then I'll make a start on the the F3-RES creation inSeptember..

 

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Whitmore

Wow, that's gorgeous!

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martynk

Yeeey -- it flies.

Had a maiden last night. Flat calm but with a couple of minor problems. I was Billy no mates so no photos.

I forgot to set the brake on the ESC so it freewheeled rather than folded and it has quite a right turning bias which is trimmable on rudder, but its not right.

All went well until I landed and one of the spoilers disconnected just above ground and the consequential wing drop resulted in the model whipping round and the fin becoming unglued. I realised that the epoxy to boom join had failed - or rather not attached properly, probably because I had forgotten to remove the release agent from the inside of the boom.. Doh

So in the workshop last night and I realised why the spoiler disconnected - it was because the snake outer had detached at the root. So re-glued that, and the fin and setup the ESC for take 2 this morning. I also checked the lateral balance and added about 15g of Plasticine into the left tip,

This morning was different, All the glue had set, the rudder deflection was increased, the spoilers now working and the first flight was nearly 20 minutes from a single 10 second motor run.. A very happy bunny. A total of three flights - the other two were not as good as the first.

Still trying to turn right but not horribly so.

A few photos - not all as sharp as they could be.

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Prep

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Launch

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It flies 

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Still flies

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Approach

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And a sort of touch down :)

Need to sort out that turn bias, however, the glide is absolutely stunning, very flat and certainly with more than adequate penetration for this mornings gentle breeze.

I'll add a Vario for logging and a 30 second programmed run.

Static running - its drawing 20A/210W on a Grapuner12x6 on a 970kV Turnigy motor. Gives a reasonable 30 degree climb which seems adequate. Time will tell.

 

Special thanks to Jef Ott for his support and guidance - really, really appreciated

Now I need to practice, practice, practice..

 

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Jef Ott

The dihedral looks perfect (to me) in the flying shot, for an RES model Martyn.

Well Done, a great project!

Thanks for the nod :) 
 

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martynk

Thanks Jef

a couple more observations. Before I flew on Friday evening  I went back to my free flight days and tested the glide from a hand launch. Observation was that it was seriously under elevated so I adjusted the trim accordingly  when I double checked this morning the CG was about 12mm too  far forward.  I had originally set the CG with a 2S liPo but replaced that with a 3S. I was amazed how much difference that made. I had to move the Rx battery back under the  wing to compensate then reset the tail. Flew perfectly today with the CG correct (32% MAC). 

I have used a 40A opto isolated ESC - seems quite adequate for this - at the moment. 

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Jef Ott

Martyn,

Don't worry about the weight, if you are planning on flying it in fixed height competitions, E-soaring, Bartletts Rules, MLG, BARCS Restricted etc., the weight is perfect for most competition days (my 100" Bartletts Class models are 1125 and 1650g IIRC).

There may be an advantage for lighter models in F5J in really light lift conditions, but to be honest an 100" model is at a disadvantage for that formula of competition anyway. 

This is why I have separate models for F5J and Bartletts comps.

Jef 

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martynk

Cheers Jef. 

Thsts broadly what I anticipated. The wing should be strong enough for a tow launch if I want to use a conventional glider fuselage. That may be a plan B. 

Next Job though will be the F3-RES.  That should be an interesting project. I have also been toying with the idea of a carbon skinned full function F5J  at about 3.3m in 4 36" panels. (Economies). I need to have a play with the manufacturing technology though and see how stiff and flexible and light I can make the skins to see if it's a workable idea or not. 

I'll put some thoughts down while I'm on holiday.  I think you suggested an RG15 would be a good choice of wing section. I'll start there :)

 

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Whitmore
On ‎01‎/‎06‎/‎2016 at 13:39, martynk said:

Main carbon spar caps have been glued up and a taper added to the boundary.

Hi Martyn, would you be able to give some more details of the spar cap dimensions please? Are they pultruded or laminated from sheet?

Thanks,

Jon

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martynk

Hi Jon

 

From memory - the plans don't quite reflect what was actually assembled.. :blush:

All the caps are 10mm wide - top and bottom.

The inner panels are 10 x 0.5 mm top and bottom

The middle panels are 10 x 0.14 top and bottom

The outer are 10 x 0.14 top and 10 x 0.07 lower

In addition, the inner panels have 10 x 0.5 doublers to help reduce the sudden stress discontinuity at the end of the joiner block. The top has a doubler going out to R6 and the lower going out to R5

Spars bound with Kevlar thread and epoxied so seal. Never really too sure just how many windings are really required. I have seen some photos of windings which I think are OTT > i thought the real purpose was to prevent the caps de-laminating from the webs which should only require a secure but fairly close spacing for the windings. May be totally wrong about that though..

The caps are a mixture from Hyperflight for the 0.5 poltruded strip and also cut from unidirectional carbon sheet for the thinner sections (from Mike Woodhouse).

It certainly survived a 500 foot vertical descent when it disappeared into cloud a few weeks ago and I needed to get it out in a hurry - as I had lost sight of it, it took me a few seconds to pick it up again - and only just in time.... it was coming down very fast where I wasnt looking. My spotter didn't spot it either

I did think about using the wings on a dedicated 100S glider for a winch launch. In hindsight, I wish I hadn't tried to compromise, I could have made it lighter and easier to build.

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Jef Ott
52 minutes ago, martynk said:

It certainly survived a 500 foot vertical descent when it disappeared into cloud a few weeks ago and I needed to get it out in a hurry - as I had lost sight of it, it took me a few seconds to pick it up again - and only just in time.... it was coming down very fast where I wasnt looking. My spotter didn't spot it either

I did think about using the wings on a dedicated 100S glider for a winch launch. In hindsight, I wish I hadn't tried to compromise, I could have made it lighter and easier to build.

Perhaps you would not have a glider at all now, if you had done that though. I reckon a 500ft dive can be about the same as a 500ft winch climb in wing stressing terms. Have heard a big lightweight electric model wing collapse through the pilot (in error), just putting too much speed on the model before braking, which then fluttered the wing. 

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martynk

A very fair point Jef, it was moving very fast indeed on the way down. I hate to think what would have happened if I hadn't spotted it - still a few hundred feet up but only seconds from total destruction..However, I still think you should design a model to optimise a flight not survive a crash.. :) 

That wing is very strong but I could have saved about 30g in excess materials if it had been dedicated. Probably not really enough to lose sleep over..

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Rennell

Nice Computer Aided Design of plane.

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