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Gentle Curves - Lucas his Skywriter

Build blog - MB2017 - Skywriter

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Peter Miller12/01/2017 08:50:15
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11117 forum posts
1309 photos
10 articles

One of my main problems is that I am always thinking of the next model while building the current one Also I admit that I am lazy and want to get the current project in the air.

From time to time I do get the urge to build sometthing rather special and can produce a good model.

b-17 1.jpg

rhapsody.jpg

For a few years I scratched a living making desktop models (mainly sailpanes) in lime wood to order. There I did have to achieve perfection and it was a constant strain. It also took away most of the pleasure of my own modelling.

bulldog 005.jpg

bulldog 003.jpg

john stones 112/01/2017 18:39:31
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11541 forum posts
1517 photos

Yep i follow that Lucas.

Nice desktop model there Peter yes

John

McG 696912/01/2017 20:00:34
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3251 forum posts
1233 photos

Hallo Lucas,

Very tidy approach as usual. yes

But may I allow me a question, please. In your quest for tail lightness, why didn't you decide for 'build up' tailplanes as you did for your Ballerina? Possibly even with some 'laminated' LE & TE?

Cheers

Chris

Lucas Hofman13/01/2017 07:10:46
668 forum posts
375 photos

Hi Chris,

I wanted to have the "ribs" showing through the covering for the elevators and rudder. In addition the radius of the corners of the elevators is very small. But as you can see in the picture below the LE of the stabilizer is laminated.

img_3583 (small).jpg

Al the leftovers from the Ballerina spars find there destination here. Quite of bit of air compared to the original. I intend to put 1/4'' square where the stab leaves the fuselage (to attach the covering) and leave the center empty. Glueing LE and TE should secure the stab well enough I would think. Or do I miss anything here?

Lucas

Lucas

McG 696913/01/2017 07:52:19
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3251 forum posts
1233 photos

Nice, Lucas. I see your point now.

If I'm right, there is still the 4th stab rib missing to the right of the pic.

If you leave the centre section 'open', I would add a spanwise straight doubler at your laminated LE for reinforcement between those 4th stabs and then add your two 'covering support' pieces.

Just my 2 euro cent, here. wink

Cheers

Chris

Lucas Hofman16/01/2017 06:51:52
668 forum posts
375 photos

Only a little progress this weekend (but quite a bit of flying). The stabilizer is glued together. Next is hinging, making the elevator joiner and rounding of or bevelling all sides.

img_3591 (small).jpg

McG 696916/01/2017 17:11:33
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3251 forum posts
1233 photos

Tidy job there, Lucas.

I see that you added a doubler to the LE & TE... and that your small 'Banggood bottles' did arrive. yes

Cheers

Chris

 

Edited By McG 6969 on 16/01/2017 17:14:02

Lucas Hofman17/01/2017 07:01:39
668 forum posts
375 photos

Yes Chris, I did. The doubled leading and trailing edge provide enough glueing area to hold the stabilizer in place. The whole stabilizer is stiffer then anything I have made before - the "ribs" could very well have been 1/8x1/4mm (6x3mm).

This stab was made of the leftovers from the Ballerina. The next one will be leftovers from the skywriter, which will include 6x3mm stringers...

Lucas

Lucas Hofman18/01/2017 16:25:19
668 forum posts
375 photos

Fitting the motor to see where the firewall will come. I will use a 3542-800kv motor on 4S. That motor is, including the propeller mount 46mm long. Including the motor mount will bring it on 49mm. If we want the backside of the propeller 4mm in front of the cowl (the 2 degrees downtrust will make it nearly touching on the bottom right side of the cowling then the firewall move about 20mm forward compared to the drawing:

img_3593 (small).jpg

A pleasant side effect is that the hatch becomes 20 mm longer, which will make inserting the battery easier. And the battery moves 20 mm forward too.

Lucas

Lucas Hofman19/01/2017 21:26:12
668 forum posts
375 photos

Marking the firewall. To get the center of the propeller in the center of the plane the motor mount need to be a little up an to the port side. 50mm (the length of motor, mount and half the propeller) x tan (2 degrees) is about 1.9mm. Rounded up to 2 and marked on the wood:img_3596 (small).jpg

Note the strip on the bottom that has to be cut off due to the firewall moving forward. No holes (except for the center) - I want all air to go under the firewall, flowing around the ESC that will be mounted under the battery plate. Thereafter up around the battery and out trough holes in the cockpit.

The latter is unusual but since this plane, like the Ballerina, is mostly used on snow and ice I do not want holes in the underside of the fuse. They may scoop up snow that then melts inside.

Lucas

Lucas Hofman22/01/2017 16:32:39
668 forum posts
375 photos

If one want a backmounted motor and the battery immediately behind the firewall the shaft needs to be shortened. Here one needs to keep in mind that and metal dust will gladly be sucked in the motor by the strong magnets there and will do no good. Probably the best method is to remove the shaft and shorten it on a lathe, keeping the bell far away. But this comes close:

img_3601 (small).jpg

Put a piece of masking tape on a zip-lock bag. punch a hole in the bag 1 mm smaller as the axle. Seal the hole in the back of the bak. Put the motor inside, axle through the hole. a piece of wood for physical protection of the bag and a cutting disk on the Dremal make short match of the surplus axle. file any sharp edges

Do not forget to vacuum clean the outside of the bag and your hands before opening the bag and your are done.

Now the battery will not be punched by the motor shart protuding through the firewall

Cheers, Lucas

Lucas Hofman23/01/2017 21:20:36
668 forum posts
375 photos

Big pieces feel like much progres! Cut the fuselage sides and the doublers tonight and glued them together. Hurray for 3M 777 permanent mount spray glue. Very quick and consistent glue thickness and (since it is not water base) no warping of the wood.

Although chances of the latter are not big anyway when "clamped" like this:

img_3603 (small).jpg

"Clamping" this way slows the drying process a lot. Not an issue with sprayglue, but when using white glue or aliphatic glue it takes much longer.

Lucas

Lucas Hofman25/01/2017 07:04:14
668 forum posts
375 photos

Small steps. A little progress on the fuselage sides:

img_3605 (small).jpg

Chris Barlow25/01/2017 22:43:33
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1904 forum posts
1308 photos

Brilliant machines once you get used to them!

That's a lot of cutting. Wouldn't fancy doing all that by hand!

Lucas Hofman26/01/2017 08:37:31
668 forum posts
375 photos

Last night I attended a club meeting where the reigning F4C (scala) champion of Norway showed his model. That was a Stearman, sort of a Skywriter but twice the size.

Fuselage sides are ready now:

img_3611 (small).jpg

I had to make a wing template to sand the shape in the fuselage sides accurately.

Lucas

Lucas Hofman27/01/2017 07:19:57
668 forum posts
375 photos

A little progress every day:

img_3613 (small).jpg

The squares on the cutting mat give a good guidance to get everything square (and my rectangular sanding blocks help keep the former perpendicular to the surface).

Lucas

Lucas Hofman27/01/2017 18:55:57
668 forum posts
375 photos

Glued the doublers on the inside of the fuselage in place tonight:

img_3616 (small).jpg

The article accompying the RCM&E drawing is quite sketchy on the the building part, or rather it does not contain any pictures of the build. However, Lindsay build blog is very good and more then compensates.

Lucas.

ps. please say so it all these small steps are boring.

McG 696927/01/2017 20:15:05
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3251 forum posts
1233 photos

Hi Lucas,

Any forward step isn't "boring" at all, young man. yes

I'm afraid that your lack of reactions is just due to the fact that the 2017 Mass Build very certainly isn't as successful as last year's Ballerina was.

If you compare all the 'first 5 points" the Skywriter got in voting to the number being concretely built - or projected in the near future - at the moment, there is some kind of a problem with this MB.

Just keep it up. You're doing great as you did last year. wink

Cheers

Chris

john stones 127/01/2017 21:35:55
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11541 forum posts
1517 photos

Not boring, it's informative wink

John

Chris Barlow28/01/2017 01:20:35
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1904 forum posts
1308 photos

Lucas, I notice from Johns photos in his blog that I've forgotten the 1/8th balsa fillets to the rear of the wing seat on the fuselage sides. I notice I'm not the only one!

Also I see you're cutting your own parts? If you're using the original plan in the mag then watch out for former F4a which was to small in width on my plan. Fortunately I used the top section of F4 to mark and cut F4a.

Finally as above, not boring at all. It takes a lot of time to take the photos as you go along and document each step in a detailed blog, but it will be extremely useful for first time builders.

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