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Gentle Curves - Lucas his Skywriter

Build blog - MB2017 - Skywriter

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Peter Miller05/01/2017 09:09:26
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7965 forum posts
885 photos
10 articles

Going back to laminating tips.. (Just picked up on this thread.

Pinning the strips down wet and leaving them to dry is the best way to go. I like to incorporate a lamination of 1/64" ply in the tip, preferably the innermost lamination.

Lucas Hofman08/01/2017 14:42:59
395 forum posts
218 photos

Peter, what will the 1/64'' ply do when used as inner layer? Add compression strength (like doublers on a fuselage)?

Lucas

Lucas Hofman08/01/2017 14:43:00
395 forum posts
218 photos

Peter, what will the 1/64'' ply do when used as inner layer? Add compression strength (like doublers on a fuselage)?

Lucas

Lucas Hofman09/01/2017 07:14:07
395 forum posts
218 photos

Continued with the ply and balsa bits during the weekend:

img_3573 (small).jpg

It give a some satisfaction laying it all out out on the drawing. A little bit like completing a jig-saw puzzle.

This is all the preparation for the fuselage I think. For some reason I have always made the tail surfaces first. Maybe because you get a part finished very quickly. See if we can make a start tonight.

Lucas

Peter Miller09/01/2017 08:19:49
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7965 forum posts
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10 articles
Posted by Lucas Hofman on 08/01/2017 14:42:59:

Peter, what will the 1/64'' ply do when used as inner layer? Add compression strength (like doublers on a fuselage)?

Lucas

It helps stop the kinking at the pins if you have internal pins it also addds some strength but isn't really essential I justblike it if Ihave some spare 1/64"ply.

Peter Miller09/01/2017 08:21:24
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7965 forum posts
885 photos
10 articles

Theyways reccomend thatfull size homebuilders build the fin orrudder first sothey have a complete bit to look at.

Lucas Hofman09/01/2017 08:25:45
395 forum posts
218 photos

It is all about how to keep a good feeling through the whole process! (or at least through most of it).

Do you have any new projects underway Peter?

Lucas

Peter Miller09/01/2017 08:31:27
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7965 forum posts
885 photos
10 articles

I have had this really bad cold since before Christmas and haven't had any interest in anything. Starting to recover.

I am finally thinking of starting to build a 62" span Buzzard Bombshell for a .30 FS. If I can summon enough energy.

Lucas Hofman10/01/2017 07:50:24
395 forum posts
218 photos

Started on the tail feathers:

img_3577 (small).jpg

I keep the original construction (converted to imperial sizes to match the balse I have) to preserve the ribs showing trough the covering. Some lightening holes it will be. I use a dremel with a router bit to cut these out)

Lucas

Peter Miller10/01/2017 08:37:19
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7965 forum posts
885 photos
10 articles

From past experience those lightening holes should save all of a couple of grams.

Once I found that out I never wasted time again with them.

Lucas Hofman10/01/2017 08:59:38
395 forum posts
218 photos

True.

When I was at university the Fokker the Fokker F28 was in its final design stage. Fokker had some throuble with weight creep and offered a bonus to all employees to come up with ideas to save weight. The amound was - if I remember correctly about 10 GBP per gram. The results was a couple of hundre kilograms saves. By a few hundred grams here and a few hundred grams there.

Rough calculation is about 4 grams saved at the tail. Since I expect some lead will be needed in the cowl the amount of lead saved is about 20 grams. That is 24 grams saved with about 10 minutes of work.

It is up to the builder if this is worth it.

Lucas

Lucas Hofman11/01/2017 07:19:29
395 forum posts
218 photos

img_3580 (small).jpg

Weight difference is 1.4 gram. It was (for one elevator) more then 10 minutes work. I very much hope that there is weight in the cowl to save, otherwise it is quite meaningless....

(but then, as my wife says, it keeps me off the streets)

Lucas

Simon Feather11/01/2017 09:24:41
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116 forum posts
112 photos

Going well, Lucas - I'll catch up with you eventually but need to finish my KF3 anniversary build first. I don't think I'll bother with those lightening holes!

Simon

Rob Ashley11/01/2017 09:34:34
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34 forum posts
2 photos

Lucas,

You are doing a very neat job - I am watching this with much interest. As your wife says 'If it keeps you off the streets" then cutting them out must be good. My build of a Peter Miller Grumpy Tigercub (enlarged to 72" span and retaining IC engines) has stalled in the last couple of weeks, but having read this forum I am beginning to rejuvenate my enthusiasm.

Keep going

Rob

Lucas Hofman11/01/2017 09:57:39
395 forum posts
218 photos

Thanks for the nice comments gents Looking forward to glueing the tail feathers together tonight. The weather is deplorable which makes the workshop a nice place to be!

Lucas

ps. found out yesterday that pull-pull wire and clamping pieces are very good to hang paintings on the wall with!

Lucas Hofman11/01/2017 21:44:15
395 forum posts
218 photos

The rest of the holes went quickly.

This evenings results:

img_3581 (small).jpg

and

img_3582 (small).jpg

I bought all wood in the UK so the thickness of the tail feathers will be 1/4 inch (6.1mm). The rudder and elevators are build up from 3/32'' (2,4mm). They will become 7.2mm thick to start with, and will therefore need some sanding. Reinforcements are 2mm light ply (at last can I use it for something).

Tomorrow the reinforcement on the other side.

Lucas

john stones 111/01/2017 22:06:42
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7856 forum posts
1285 photos

You're a much neater builder than me Lucas yes

I thought the bottom piece on Fin was square from t.e - l.e ?

John

Chris Barlow11/01/2017 23:28:08
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1592 forum posts
1108 photos

Agreed Lucas, best to save weight from the beginning and at the tail if you suspect you'll have to.

My wife says if I spend too much time in the workshop I'll be out on the streets! surprise

Lucas Hofman12/01/2017 07:22:30
395 forum posts
218 photos

John, it is the leading and trailing edge stock that keep the fin vertical. The bottom piece, with the grain lengthwise, does little in preventing the fin from bending when loaded sidewise. The bottom piece needs to hold the covering (keep in mind there will be no covering where it it glued between the side pieces).

I had loads of 1/4'' square left after the ballerina wings, and a 1/4'' piece of scrap that fitted at the bottom. Had that piece been wider it would have been square. There is no deep thinking here

Yes, I think I build quite neat. But very slow too. I estimate Peter Miller builds about 3 planes for me doing one. And then he designs them too. Mine may look a little better, but I am sure the fly the same, so I am not sure what to prefer. On the other hand, I would not enjoy not building neat, and that is the purpose of the whole activity isn't it.

Lucas

Lucas Hofman12/01/2017 07:30:09
395 forum posts
218 photos

Chris, I majored in aerospace technology (although I never worked in that field). On any full size you will not find a rib, former or rudder horn without lightening holes wherever possible. I think the mindset sticks.

Our models have usually much more power compared to full size planes, so the need to shave weight both here and there is less.

I may very well be that the most honest answer to the question "Why do you save weight Lucas?" is "Because I can".

So do not worry too much about it.

Lucas

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