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S1581 Hawker Nimrod MkI

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Danny Fenton02/12/2018 10:59:08
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9200 forum posts
4044 photos

This may Help José Luis?

Nimrod II but it appears to be the same in this area on the Nimrod I. I read that it may be to do with the catapault system, though I am not convinced, it looks too far back and behind the c of g?

nimrod ii wing root.jpg

Cheers

Danny

 

Edited By Danny Fenton on 02/12/2018 10:59:36

Martyn K02/12/2018 19:31:06
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4977 forum posts
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Looks like half a bay is missing Danny

Martyn
Danny Fenton03/12/2018 15:15:11
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4044 photos

Martyn it is difficult to reconcile the three view and the pictures to be honest.

nimrod 1 3 view plan view snip.jpg

On the three view it is an entire bay, however that picture looks like a half? The picture trumps the three view every time, however the rib layout doesn't match what we have from Dennis, so it will never be right.

I have reduced the gap to half a rib bay as the picture alludes to, still not sure it looks right crook

Cheers

Danny

Jose L. G.03/12/2018 15:38:14
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180 forum posts
133 photos

Ok.

Dear Teacher, I`m guilty. I havn`t looked at the Nimrod Pictures. Hope not to loose some points….

Cheers.

José L.

Martyn K03/12/2018 16:12:35
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4977 forum posts
3624 photos

This is difficult Danny. Makes it fun though. I am still trying to fathom out how to do a floating fin and tailplane.. :D

Danny Fenton03/12/2018 20:52:19
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9200 forum posts
4044 photos

Managed to get the starboard wing capped and the leading edges sorted. Just the leading edges to add and I can give the wings a good sanding

005.jpg

Cheers

Danny

Danny Fenton04/12/2018 15:35:51
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9200 forum posts
4044 photos

Ploding onwards:

I attached the soft 1/4 inch leading edges to the lower wing panels and then turned my eye to a gadget. If you read my column from the start, you will know I like sanding aids. I didn't savour the thought of sanding 4 wing panels, plus two leading edge sections, attempting to make the radius and shape exactly the same. I turned to cad and traced the leading edge section. I then applied an offset to make the line 2mm outside the leading edge profile. I want to line the tool with 1.5mm balsa, and .5mm thick 120 grit sanpaper.

Printed the parts and stuck to some 1/4 lite ply.

006.jpg

Bandsawed to shape

007.jpg

Sanded and glued to some bits of scrap

008.jpg

Lined the inside with 1.5mm balsa soaked on BOTH sides with ammonia010.jpg

When dry, the balsa was glued in place.

009.jpg

Sandpaper was glued to the balsa face and the whole lot trimmed and sanded to look pretty.

012.jpg

A quick test, and then the final result.

013.jpg

015.jpg

The edges can dig in if you don't hold it perfectly straight, perfectly manageable but the addition of some tape to blank off the last 1/16 of sandpaper at each edge would make it perfect.

Now the leading edges are not at all daunting

Cheers

Danny

Richard Mallam.04/12/2018 16:56:23
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54 forum posts
7 photos
Hi Danny, clever stuff. I'll get some Cad s/w. On another point, I have made both upper and lower wings with hard balsa spars and inserted vertical grain webbing between them. I happen to have some 1.2mm carbon rods and was thinking that it might strengthen the structure if I inserted them on top of the spars, but underneath the capping strips. What do you think? Richard
Danny Fenton04/12/2018 17:11:17
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9200 forum posts
4044 photos

I can post a pdf of thes parts if other want to make one

Hi Richard, really you must go in the direction you feel is right. I am a believer in a light weight model. But in fairness maybe my models are not very rugged, and I dont fly them much. So perhaps I have just been lucky to not have had any structural failures, perhaps not. I am sticking with my balsa spars, it sounds like you have done "I" beam spars like Andy has done on his. The webs go between the spars. Very fiddly and the joints need to be accurate to give full strength. But they are adding a lot more strength than Dennis suggests on the plan.

The problem with adding things is the weight. I know things don't seem much, but they add up, the carbon rod + glue. People often forget the adhesive.

Cheers

Danny

Richard Mallam.04/12/2018 17:28:49
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54 forum posts
7 photos
Thanks Danny. I'll sleep on it. Just to be clear, my webs are not like Andy's - they are immediately behind the spars, not in between. Richard
Danny Fenton04/12/2018 17:33:53
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9200 forum posts
4044 photos

Hi Richard, okay so your webs span the spars the same as mine, I think they are safer, all-be-it a little heavier.

I only did the rear face of the front spar, coupled with capping strips my wing feels rigid enough. The wires do a great deal of the work

Cheers

Danny

Richard Mallam.04/12/2018 18:06:21
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54 forum posts
7 photos
That settles it. I'll pass on the carbon rods. Thanks Danny
Colin Leighfield04/12/2018 19:00:44
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5961 forum posts
2492 photos

Danny, I find it difficult to get a clean cut cross grain with thick balsa, even with a sharp blade my edges always look ragged. What do you use for work like this sanding tool? I struggle to achieve anything of that standard.

McG 696904/12/2018 19:19:04
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2621 forum posts
991 photos

... ooh... well,Colin. Now I'm quite relieved not to be the only one. wink

Things got a lot better when I use a razor saw for cross grain cutting, slow and gentle. Just a mm oversize and a bit of fine sanding. Wondering what our Master's trick for it.

By the way, Danny. Happy to get that wonder-tool drawing for the LE shaping. yes

Cheers

Chris

Danny Fenton04/12/2018 19:55:56
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9200 forum posts
4044 photos

Thanks Chris I will convert it to PDF and mail it out.

Okay Saws according to DWF - I am with Chris, a good quality razor saw is the answer. I do sometimes use a very sharp scalpel for sheet but above 1/16 it's the saw every time. I also rarely use a ruler and knife for lengthwise cuts also, I favour the balsa stripper.

016.jpg

These are some of the saws I frequently use. These are "Zona" saws, they retail for about £10 - £15 each. They are lovely to use. The Zona saws are for nothing but pure balsa. The blade labelled two has not been used yet as one still has a terrific edge.

The red handled cheapo is for ply and harderwoods, spruce etc. As the red handled ones loose their edge they are relegated to glass fibre cutting duties only. Glass fibre/carbon destroys a blade.

For ply or bigger bits then the bandsaw rules the roost.

So nothing secret or clever just good quality saws.

Oh and one more thing, I saw on a scrap of 1/2" balsa, the block tends to last 5 or six years before I need a new one. Treat the blades like gold and they will last.

Cheers

Danny

Edited By Danny Fenton on 04/12/2018 19:58:23

Colin Leighfield04/12/2018 21:13:31
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5961 forum posts
2492 photos

I use saws for the straight cuts but find curves difficult, except where I can use a fretsaw.I was struck by the accuracy and clean edges of the profiles in your sanding tool.

Danny Fenton04/12/2018 21:28:04
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9200 forum posts
4044 photos

Ahhh okay now I am with you sorry Colin.

You could see where the ply parts were roughly bandsawed out? well after that I used a fine rat tail Permagrit to sand the lite ply to the line. I always sand to the line, you could use an axe to get close smile p

Once it was all glued together then I ran a sanding block over the edges. I know how this is going to sound, but I am very lucky to have a good eye for sanding/cutting/filing a straight edge. Decades of cutting and making things I guess, not just models. Nothing special just practice and check things with an engineers square.

Having said that, I cringe when I look at some of these ribs and centre section, it is not to my usual standard, bits are not square

I feel a video coming on.... "how to sand true edges to stuff", its really simple and I am sure you have seen it before, but just in case I will try and put the video camera on charge tonight

Cheers

Danny

Does that help Colin

Colin Leighfield04/12/2018 22:50:48
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5961 forum posts
2492 photos

It does Danny, thank you. Nothing changes the fact that I am somewhat ham-fisted though! Only been doing it sixty years, perhaps I’ll get there eventually.

Danny Fenton04/12/2018 23:19:46
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9200 forum posts
4044 photos

Fitted the outer panels so that I could allign the nose ribs and trailing edge ribs. Added a few bits to tidy up the centre section, and got the lower surface sheeted. The plan shows that the area between the two rear ply plates is infilled with block. This is to avoid the area being crushed when the wing bolts are tightened. Having tried to compress the plates, I see no need for the infill, so have omitted it.

Interestingly I weighed the wing, bear in mind I have added 30 + riblets, and also have some sheeting to add tothe centre section, I reckon 190g is reasonable.

017.jpg

018.jpg

019.jpg

020.jpg

021.jpg

Cheers

Danny

Danny Fenton05/12/2018 09:06:48
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9200 forum posts
4044 photos

The upper surface was then sheeted, sanded to clean up the edges, and then the 1/4" leading edge was added.

022.jpg

023.jpg

My very Heath Robinson dust extraction system might be of interest. I really should refine this by building a box to make it more efficient, but I thought this set up would do as a feasability study. It works amazingling well!! And allows me to sand indoors

024.jpg

Cheers

Danny

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