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Build Log for Krick Grunau Baby IIb (1/4 scale)


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I tidied up the skid - but time will tell how successful it will be for aerotowing purposes.
The two small yellow lines denote the COG, and the black stripes on one panel should make it go faster ( Cheat lines to cover previous damage )
I also bought some white solartex to recover similar damage on the other wing panel underside
 
Cockpit floor fitted and painted and windscreen fitted - original instrument panel just visible

So apart from sorting the wing fitting and installing Max, she's done.
Looks rather well I think
With the Indian summer here at last, I may even get someone to give her a tug next week
 
Or, of course, I could just chuck it off a big rock

 
 
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You're making me feel a little jealous now Tim.
I feel like I've got years to go before I'm at that stage.
 
In fact I'm slowing down a bit now as I feel I've spent too much time on it this summer instead of actually doing any flying of other models.
I think I'm going to finish the fuse, then pause and start the wings over the winter.
I keep thinking the fuse is finished but there always seems to be more to do.
 
I'm half tempted to start covering the fuse, but I really want to get a photo of it fully built, but uncovered; I like them like that.
 
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I know what you mean Martyn, a long build can sometimes get tiring, and if like me, you occasionally get fed up with the whole thing, it gets even longer!
Rather than feel jealous, hopefully the pictures will help to inspire you again - your plan sounds a good idea to me, get the fus finished, then have a short break, and start the wings later.
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The bottle screws didnt work well - there just wasnt room to "operate" them.
I decided to use a ply strap across the wing roots - with 4 cheese head 4mm screws that fix through into threaded insets which I mounted at the wing root, and then recovered. This also has the advantage of covering the wiring aperture on the fus top.
I couldnt go all the way to the very leading edge due to the curvature of the wing profile being too steep to allow the ply to flex and fit neatly.
Seems to be secure, and certainly holds the wings aligned better - and I think - looks fine.
 


 
I reckon Max looks pretty reasonable in his office too
All finished now, and ready and waiting for a nice day to throw it off a big cliff.
 
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Funny you should mention that...its a rather ugly attempt to cover up a sliding spring loaded hatch retaining pin - I have just finished turning down a pitot tube assembly which will replace it, and I shall use magnets to retain the hatch.
I'll post some pictures when its done later today
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Cheers Stefan - you know, there are plenty of pretty inexpensive small model makers lathes around these days, and S/H are of course even cheaper. I have lost count of the number of things I have made for use in this hobby - and apart from the usefulness, I get a great sense of pleasure from turning pieces on the lathe... very satisfying.
Off topic...sorry .
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Well done Tim , looks great !.
Like the piece of window frame on the glazing, nice touch.
What is the shank size of your lathe tools Tim , I'll have a rumage at work, Have you a miller or vertical slide ?
Perhaps I missed something but why a 1/5 scale dummy in a 1/4 scale model ?
 

Edited By Fubar on 06/10/2011 18:37:45

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  • 2 weeks later...
Getting back to doing a bit of work on the fuselage, but mainly just sanding and fitting out the cockpit, and more sanding.
On the last plane I built (DB S&S Cirrus Moth) I did a very basic cockpit and planned to tart it up later, but of course never got round to it.
So I thought I'd have a go at a better one on the Baby.
I still haven't found a suitable 1:4 scale pilot, - I'll have to have a shop around again soon.
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Nice one Martyn, looking forward to seeing her finished.
Right, just to conclude my intrusion on your thread, I maidened mine yesterday.
Conditions were far from ideal for this one, with approx 30MPH slope wind, but we went for it anyway. I messed the landing a bit - by allowing her to get too far behind, and being big and bulky and relatively light ( 8.5lbs ) - and draggy - she doesnt penetrate at all well.
One airbrake failed to deploy, so the resultant slight yaw didnt help me, but I popped the other one down.
I doubt that in anything other than almost flat calm conditions airbrakes will be used TBH.
The skid broke away at its front mounting point - and when I investigated further, back home, its no wonder, It was fixed to balsa sheet and rib only !!

The nose of the model is balsa block, so I will make a new, slightly longer hardwood skid, and fix it to that part instead, and also fill in the cavity where it was fixed, with ply and expanding foam.
It flew OK, and is what it is...a lumbering big 'ol vintage scaley which should look and fly far better in 0 - 10 MPH.
Ailerons are surprisingly weak considering their size, so lots of rudder needed to get the turns tidier. Elevator was a tad pitchy, so I may shift the COG forward a little ( the skid repair work should accomplish this anyway )
Short clip ( under 2 minutes ) on the tube.

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  • 2 months later...

I was determined to get back to building the Grunau this weekend, so that I'd have something to write here..>>

It's the wings next; - good grief, they look big on the plan.>>

I scarf-jointed two of the 1/8" x 5/16" spars to make one 66" long spar, then I cut the remaining piece as a doubler. (four times, - top and bottom on each wing). This doubler is supposed to overlap the joint, but I cut it completely wrong, so I've now got to go shopping and find some more pine. I did exactly the same on all four spars - Bugger.>>

I suppose I could join it back together, but I don't want any more joints in the spars than I really have to. >>

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After a real screw-up on the spars, I've been shopping for some more 1/8" x 5/16" spruce spars.
I t seems that everybody only does this sort of wood at 1m lengths, (maybe they cut t from very short trees ?).
Eventually I tried 'SLEC' and they were wonderfully helpful.
They cut me some wood, at 2m length, so no need for a scarf joint in the middle.
Great service - thank you.
Maybe I can get on and do some building now.
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