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Martyn's Chippie RCAF 671

My first proper scale model

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Martyn K02/06/2014 09:52:30
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4294 forum posts
2959 photos

I have never ever built a scale model - apart from a few peanut scale models which I never seem to complete. I have been building a 13" span Piper Cub for nearly 3 years - it may get finished in Italy this summer.

What do I hope to get out of this? Broadly, I want to improve my building skills, I have been building aeroplanes (and boats) since I was 12 or 13 years old - about 45 years. I am therefore considered to be quite experienced but I am not a good builder by any stretch of the imagination. I am in awe of people like Danny who produce a work of art with all joints absolutely perfect, finished perfectly and the only imperfections in the surface are intentional - where the rivets pop through..

I would like to try a bit of that and I see this build as a (possibly - very) slow build which will take a back seat occasionally while more pressing repairs/maintenance/replacement of my usual hacks takes place (I normally build 2 models at once anyway). The Chippie will be reserved for those quality time moments when I need to be able to take more care and demonstrate real patience.

Things I am looking forward to are:

1. Having a working undercarriage that is strong and accurate enough

2. making a pilot or two

3. A bit of cockpit detail - instruments that look like instruments

4 Not sure about the rivets though.... nerd

5. Working with litho

6. Writing up this blog

I have already got the plan, canopy and cowl. I think that I will buy a cut parts wood pack as well in due course.

I have got a Enya 60 F/S to power this. I am hoping that I can get a scale working exhaust as well..

The aircraft I am going to attempt to replicate at 1/6 full size is this...

chipmunks10216032165.jpg

I prefer civilian colour schemes. Hopefully, I may be able to get access to it to photograph it closely - its down south somewhere so it will be an excuse to get a weekend away camping.

Best wishes

Martyn

john stones 102/06/2014 10:47:51
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8561 forum posts
1358 photos

Like your colour scheme as well Martyn, I share most of your aims but will leave the camping out.

John

Danny Fenton02/06/2014 12:31:19
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8354 forum posts
3398 photos

Lovely colour scheme Martyn, I am getting quite nervous at the responsibility of this build crook still looking forward to it though smile p

Cheers

Danny

Martyn K16/07/2014 15:53:44
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4294 forum posts
2959 photos

I ordered the parts kit from Traplet which arrived just before I went on holiday. As first glance, the wood quality appears to be quite reasonable - no obvious rubbish. So now got the plan, cowl, canopy and wood kit Ready to roll.

dscn0434.jpg

Martyn

Tony Bennett16/07/2014 18:37:26
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4749 forum posts
117 photos

shall enjoy watching this build martyn.

john stones 116/07/2014 23:13:45
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8561 forum posts
1358 photos

I've got my ribs etc to cut yet, best start soon or i'll not have them ready

Enya 60fs, that should be a good combinationsmiley

John

Martyn K31/10/2014 14:23:14
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4294 forum posts
2959 photos

I have been following Danny's post with interest and wondering how to address the wing/flap/aileron problem. As I am just about to make a start on this, I thought that I may as well redo the wing with the correct rib spacing and also the flaps and ailerons in the correct position. I'll draw the wing up in Profili and get a dxf file to Dylan for cutting.

As far as I can see from the 3 view that I have and pouring over full sized photos, the correct measurements are (from Danny's post). 

 

Under surface

flap chord at root: 54mm

flap chord at junction with aileron: 52mm

aileron chord at junction with flap 44mm

Aileron Chord at tip 44mm

Upper Surface

flap chord at root: 52mm

flap chord at junction with aileron: 50mm

aileron chord at junction with flap 38mm

Aileron Chord at tip 38mm

Elevator

Root 72mm

Tip 48mm

It looks like DB has maintained a continuous hinge line which has resulted in non parallel and odd shaped ailerons and huge flaps. The aileron size at the tip is about the right size..

My plan therefore is to sanity check the key component measurements this weekend and see if I can identify any other anomalies. If broadly OK, I'll start with the fin and rudder and just be a month and a wing behind you. I'll worry about the fus after the wing has been completed. I'll re-cut/re-work the hinges to fit, cant throw away that nice cutting.

More to come..

 

Martyn

 

 

 

 

Edited By Martyn K on 31/10/2014 14:24:05

Martyn K31/10/2014 14:25:37
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4294 forum posts
2959 photos

Forgot to mention. The reason why I am late starting is that I am having an extension built at the back of the house. Just too many distractions and too much clutter to risk starting this

Edited By Martyn K on 31/10/2014 14:25:51

Danny Fenton31/10/2014 14:32:10
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8354 forum posts
3398 photos

Hi Martyn, blimey that is enthusiastic of you! Would yo ukeep the construction or make it a bit simpler to follow?

You might want to check the rest of the drawing before going to that much trouble. I think that the position of F8 on the DB plan is also out by about 1/2 inch. This changes the position of the band and fairings, and canopy. Everything knocks on if there are errors.....

Cheers

Danny

Martyn K31/10/2014 14:47:54
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4294 forum posts
2959 photos

I think the flap and aileron linkages also need some work, so I'll need to rework around the rear spars so that the top and bottom flap and aileron gaps are in the right place.

OK on the fus, just to complicate things further, I am going to build the wing with 3degs washout (IIRC) - which is actually quite a lot - and use the original wing sections with NACA2415 root and USA32B at the tip. We have the software tools to do these sort of things now, I just wish I had the space to redraw the plan properly - that wont come for another 3 weeks or so though.

When (if) I get this far, then I'll worry about the fus. By then you'll have finished yours

I still think that I can reuse most of the Traplet cut parts - its just a full set of wing ribs that will be required but I think that it will be worth it in the end

Danny Fenton31/10/2014 14:49:59
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8354 forum posts
3398 photos

The tip is slightly undercambered too, which possibly helps with the tipstalling.

Sounds an interesting project Martyn

Cheers

Danny

Martyn K31/10/2014 14:54:31
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4294 forum posts
2959 photos

I think I may be biting off more than I can handle but nothing ventured = nothing gained.. Hey ho..

Martyn K31/10/2014 16:28:49
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4294 forum posts
2959 photos

OK

Small problem no.1

Comparing the two 3-views that I have..

This image is from the old MHS 3063 - 3view

chippie-root1.jpg

You can see that the root ribs (probably 3) are tilted.

However, this 3 view stolen from t'internet

chippie-root2.jpg

Shows the ribs as being parallel up to the root. (BTW - the orientation of the 2 snips above is 180 degrees out - sorry)

Has anybody who has had a close look advise me which is correct please? I suspect its the MHS drawing.

Thanks

Martyn

Danny Fenton31/10/2014 16:49:10
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8354 forum posts
3398 photos

Hi Martyn yes the second one is wrong I have them both

3063 seems much more accurate. I have tried to do a deal with Myhobbystore to get us a discount for the three view, but so far I have been unsucesful I think £12.50 is a bit steep for what I reckon you get

Cheers

Danny

Martyn K31/10/2014 16:52:55
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4294 forum posts
2959 photos

Thanks Danny, I thought that may be the case.

I agree - it is a bit steep - I suspect that it is the contractors price though..

M

David P Williams31/10/2014 17:02:00
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657 forum posts
256 photos

Here's the real thing....

img_3630.jpg

img_3718.jpg

img_3643.jpg

so I don't think either of your 3-views are very accurate

Martyn K12/12/2014 09:30:45
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4294 forum posts
2959 photos

Well - over 2 months late - but I have made a start. The reason for my tardiness, we have had an extension built at the rear of the house and the amount of additional work that I have had to enjoy(!) has been very time consuming. In fact - since the end of September, I have neither flown nor spent much more than about 6 hours in the shed. Disgraceful.

However, I have fitted a new kitchen, plumbed it, electrics, patio, path down side of house, painted it (120sq m - 3 times). I have got a truce now until after Christmas (apart from decorating the downstairs loo - but got a couple of days off work next week for that), so I have managed some shed time this week.

To get back in the swing of things, I created a jar of glass fibre hinges.

dscn0917.jpg

Then started to look what was actually in the box of pre cut parts. As I am miles behind you lot, I am not going to do a stick part A to part B type blog, just highlight a few things that I am doing differently. I am also so far behind that I feel no urge to try and catch up, so this will be a slow build.

So I started on the tailplane and elevators. Not actually being in a position to rush into the build, has given me time to look at the plan and see where I can identify anomalies. I appreciate that it may not be gospel truth - in fact I have found errors in it, but I am using 3063 as the reference 3-view on the grounds that it should be more accurate.

I have measured the tailplane and elevators and as far as I can see, the scaled up elevators on 3063 are a few mm (about 8 IIRC) at the elevator tip than the DB plan shows. So I have redrawn them.

dscn0918.jpg

Apart from the error (corrected at the very tip, you can see the revised outline. I wonder if there was a difference between the mk 1 and mk 2 Chipmunk - the rudder got enlarged - did the elevators get done at the same time?

Note the spar and LE have been packed up ready for ribs.

dscn0919.jpg

The green rib positions were redrawn from 3063, but comparison with photos, these are clearly wrong so I am staying with the DB rib positions

dscn0920.jpg

The RH tip is a bit clearer.

dscn0922.jpg

Started on the elevators using weights to hold it all in place and allowed to dry

dscn0923.jpg

The ribs are simply strips of wood - no attempt at tapering at this stage, I'll sand it all down to size when the tailplane is finished - or rather more complete.

3 evenings work so far - having problems getting PVA glue to dry properly in the cold/damp air but at least I have made a start

More to come.

Martyn

john stones 112/12/2014 16:24:58
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8561 forum posts
1358 photos

It's a start Martyn and no one set a deadline wink

John

Nigel Day12/12/2014 16:58:33
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1156 forum posts
213 photos

Don't worry Martyn, you'll have overtaken me (and Nev?) in no time.

Martyn K02/01/2015 09:43:10
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4294 forum posts
2959 photos

A bit of progress over Christmas and the New Year. No updates though (until today) as my PC has been more or less inaccessible due to overload of boxes (still unpacking after the extension was completed just before Christmas).

But I did manage to get some quality shed time

Continued working on the tailplane and elevator..

dscn0925.jpg

Boxed in the tailplane hinges in the tailplane. When I get round to gluing them up, I know they will be in the right location. Note that I have already sheeted one half of the tailplane

dscn0927.jpg

Not the neatest bit of slot cutting for the hinges, the wood is rather light, poor close grained and hence crumbly - however, I have reinforced the joint with small 1/32 balsa gussets. makes it a lot stronger

dscn0929.jpg

With the hinges in place and aligned, I covered the other half of the tailplane.. All fairly straightforward stuff.

dscn0930.jpg

And here is my version of Danny's Sanding block - to show that I am paying attention..

dscn0932.jpg

A bit random, but here is the start of the fin and rudder. A couple of extra Gussets added (I like gussets) and I seem to have got it right first time

dscn0935.jpg

As the shed had warmed up a bit, I was joined by this Shield Bug that decided to come out of hibernation..

dscn0941.jpg

Onto the Rudder - and this where I have cheated. There was an image of a Chippie overlaid very expertly by the plan. The one thing that looked wrong was the rudder outline, so I copied the image (more or less) from the photo, back onto my plan and it looks like I am building to this outline...

I then promptly forgot to take any build shots but I do have this one..

dscn0949.jpg

I made a mess of the solid upper part of the rudder and chopped it off and re did it. I am still not totally happy yet as the gap between the shroud and the rudder is a bit wide at the base - less than 1mm but it is very noticeable when compared to the top of the fin where the gap is very snug but not binding..

More to come..

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