Jump to content

Skylab, 1/100, Scratchbuild


Recommended Posts

Skylab

 

Hi Karman line team.

 

As promised on the chat I'm switching my  Skylab project, currently on the Science Fiction and Realspace forum, into this groupbuild.  I'm well below the 25% threshold at least in terms of time to finish this project and @bianfuxia (who I understand is the boss around here) seems to think it's OK for me to pop across here for a bit, so here I am.  This is my first group-build BTW so it's all very exciting!

 

Anyhow, here's a link to the story so far...

 

I have not achieved a huge amount just yet but that's mostly because my spare time was being sunk into finishing my PzH 2000 so hopefully being in this group might cause me to focus on Skylab a bit more.

 

Here's something like what I want to make...(mine won’t have the big rocket-bit sticking out the back of the workshop because it was not there on the final deployed version).

3iB9CLG.jpg

 

and here's where I'm up to.

njLsQ3C.jpg

 

Doesn't look like much yet but hopefully it's on the right track.

 

I'm very much looking forward to being a space groupie! 

 

Hopefully I'll make some progress over the next few months.

 

See you all soon,

Bandsaw Steve

 

  • Like 22
Link to comment
Share on other sites

Solar Sail

 

I think it's fair to say that for NASA the whole Skylab experience turned out to be more 'interesting' than planned.  The most visible sign of just how 'exciting' the launch was is that once in orbit this space station - which was supposed to have two solar sails - only had one.

 

The diagram on the cover of the Haynes Workshop Manual shows NASA's intended configuration, with two large solar sails, one on either side of the orbital workshop.

t1bWTRy.jpg

 

Whereas this photo shows how Skylab actually looked in orbit.  I will discuss the rather dramatic sequence of events that caused this odd-looking asymmetry in a separate post. 

OIPCGlM.jpg


To my mind, the single sail configuration is much more interesting and is the way I will model this.  The sail is supported by a structural boom. This boom is a simple shape, easily cut out of a piece of plywood using a scroll saw.

es4P6Jw.jpg

 

But after that easy first step I started to realize that this thing is not like any other model I've ever made.  Since Skylab was designed for use in zero gravity and with no aerodynamic stresses much of it seems to have been built incredibly lightly.  In the image below we can see that the one big solar sail is actually three smaller sails that are not really connected together at all. They just 'float' next to one another each held in place by series of small struts that in 1/100 scale would be very flimsy.  I think it is  possible to build this as it was originally done but to do so will render the structure very weak and will make the accurate alignment of the panels difficult...

Lb9uP7o.jpg

 

So I've cheated. I've cut two slots on a single sheet of relatively rigid plastic and left the 'wing root' that attaches all of the three resulting panels intact. This will make the structure much stronger and will help keep the three panels aligned with each other.

4BVMxeF.jpg

 

Now comes the real cheat. On the original the solar panels do not appear to have had any visible external support, but in this case each panel will now get it's own carbon-fibre supporting rod - each drilled into the plywood boom. Later on I think I might cut a rebate in each panel to at least partially conceal these rods, but for now each panel is going to have it's own visible external reinforcement.

PohBCXX.jpg

 

I've also added a length of gridded plastic to the 'wing root' to tidy this area up a bit, however there should actually be a gap between each panel and the boom with no more than a filigree of support struts holding each panel in place. I think that later on I might add some surface detail, and maybe cut some holes through the gridded plastic, to try to represent the complex structure here.

gJOuUwF.jpg

 

Plywood has a distinctive grain that that will not make a convincing surface texture on a high-tech space station, so I've decided to skin the boom with aluminium litho-plate. . 

Hl0Q5Bi.jpg

 

Simple, flat, angular surfaces are very easy to skin with lithoplate and the result is a surface with an absolutely smooth metallic texture. This will look good once painted.  I've also added some surface detail as indicated by the three-view schematic drawings and photos.

VZbQDFg.jpg

 

Here is the solar sail in position.  There's a lot more work to go on this but I think it's a good start.

cA8vaRS.jpg

 

Onwards and upwards space team!

 

Bandsaw Steve.

 

  • Like 16
Link to comment
Share on other sites

1 hour ago, Bandsaw Steve said:

So I've cheated.

Don't you mean  -  "Adopted a flexible procedure to accommodate a variable and developing situation"? Others cheat but modelers are "adaptable". 🙂

 

Great job so far with the panels. Please continue onwards and upwards. Regards, Jeff.

  • Like 1
  • Thanks 1
  • Haha 3
Link to comment
Share on other sites

8 hours ago, ArnoldAmbrose said:

Don't you mean  -  "Adopted a flexible procedure to accommodate a variable and developing situation"?


Yes! That’s what I meant. Having thought about this last night in bed and having looked at the results again this morning I’m thinking I might have a plan that can make this piece a bit more detailed and accurate. We shall see. 🤔

  • Like 2
Link to comment
Share on other sites

9 hours ago, ArnoldAmbrose said:

Don't you mean  -  "Adopted a flexible procedure to accommodate a variable and developing situation"? Others cheat but modelers are "adaptable". 🙂

 

Great job so far with the panels. Please continue onwards and upwards. Regards, Jeff.

You'd be a good spin doctor!

 

This Skylab build is shaping up as a masterclass in scratch building!

 

For my ISS - which will be nothing like as detailed as this - I have long wondered about the whole droopy solar panel issue. Where do you obtain the carbon fibre rods?

  • Like 2
Link to comment
Share on other sites

I’m very fortunate to have an exceeding well-stocked hobby shop about 1 km from where I live. They have a huge array of modelling gear including a good range of carbon-fibre rods that are in widespread use by the RC flying model community.

 

I think any RC modelling supplies shop will have these rods. Long, thin rectangular-section beams are also available. I have often found uses for carbon-fibre material where a bit of additional strength is needed to hold an otherwise flimsy piece in place.

 

One thing to remember with carbon-fibre is to cut it with a saw (I use a fine jeweller’s saw) rather than any form of shears or pliers. Any such tool is likely to be blunted or damaged by the hard carbon-fibre material. Also they tend to crush the rod rather than cut it. 
 

 

 

  • Like 2
  • Thanks 1
Link to comment
Share on other sites

Great update Steve, lots of information and tips as always. I'm off to my RC hobby shop to get some carbon fibre rods today. Wonder if they sell gridded plastic sheet...

 

Great decisions re the solar sail attachment. I'm interested to see your cunning plan to add detail. To quote Blackadder "Is it as cunning as a fox who has just been made professor of cunning at Oxford University?"  I'm betting it is!

 

Richie

 

  • Thanks 1
Link to comment
Share on other sites

Geometry and Greeblies,

 

Much of the scratchbuilding I do uses carving to form the required shapes, however more and more I'm becoming interested in the possibilities of forming 3D shapes by creating 'unfolded' 2D surfaces and then folding them into the required 3D assembly. In this case I have decided to try this geometrical approach to creating the octagonal core of the Apollo Telescope Mount. This was Skylab's largest scientific instrument and was used for making high-quality solar observations.

 

After the PzH 2000 project I now consider a good set of digital calipers to be an essential piece of kit. Here I'm measuring the length of one of the eight edges in the octagon.

 WP7uyEp.jpg

 

And here I'm measuring the height of the overall structure.

xKsYiVp.jpg

 

Below you can see that I've plotted out the base-square that the octagon will be plotted within. A quick google search showed that when converting a square to an even-sided octagon the length of each side of the octagon must be 0.41421 times the length of the edge of the square.  Here I am about to start plotting out the resulting shape. Gridded plastic is invaluable in this kind of work. I cannot recommend it high enough and happily pay the extra $$$ for these sheets compared with blank ones.

K4Pqq0q.jpg

 

Here's the resulting mark-up.

l6Is572.jpg

 

Which can be sliced up as shown below. Note that more and more I'm tending to use razor blades for cutting plastic rather than scalpels. I find razor blades generally easier to control and that they hold their edge better. Essentially the only scalpel blades that I use these days are curved ones; to me the sharp pointed scalpel blades are much harder to control and highly susceptible to damage.

 

Note also the medical lance / needle at the top of this photo. These are can be bought for very little at any pharmacy and are intended for popping pimples, however I've found that these are extremely useful for a number of modelling tasks including:

  • Holding and maneuvering small plastic pieces.  Just gently stab any piece of plastic and it will be very securely held on the spike.
  • Making precise mark-ups on plastic sheet. A pin-hole is much more precise than a pencil mark and other instruments such as dividers can be precisely positioned into the small resulting hole.
  • Scribing or making detailed, precise cuts in plastic, especially since I've found that a sharp point like this tends to wander less than a blade when tracing along a steel straightedge.

xrkzahO.jpg

 

After careful cutting we have a flat unfolded structure that looks like this.  At this point I decided to start adding the various detailed greeblies that I think will greatly enhance the appearance of this model.  Although I'm calling these 'greeblies' all of these are all reasonably accurate and do represent real components on the original. I decided that it would be much easier to add these details to the flat 2D shape rather than the finished 3D structure and this proved to be the case.

lk3UWjz.jpg

 

A couple of years ago our electric oven needed a new circuit board. I asked the maintenance technician if I could keep the old defective board that he was replacing.

EnzIEPJ.jpg

 

I'm pleased I kept it. 👍  It turns out that each of the little grey square buttons on this thing are just held in place with small plastic friction lugs, a bit like a lego block, so they lift out really easily...

3AV5AXr.jpg

 

and can just be plugged in to suitable pairs of drilled holes. I admit that these particular details are over-scale compared with the considerably smaller boxes that they are supposed to represent, but they are at least all identical and look fairly convincing in my view.

N4hT5d8.jpg

 

I've added the four gyroscopic wheels that were arranged around the outside of the telescope and used for fine attitude control. The centre of each gyro is a wheel scavenged off an old kit abandoned by one of my local modelling club members.

A98C7Pj.jpg

 

With all of the greeblies in place we now cut a groove about a third of the way through the plastic sheet on the outward-facing fold line...

Cv0HFbD.jpg

 

cement some angle brackets on the inside...

UQ01mm1.jpg

 

and gently fold up each panel into it's final position. Be careful to fold each one just once (put the cement in place before you start folding). Remember the more you 'work' each fold the more likely it is to break. In this case I managed to get all eight to fold up without breaking.

NhoDkZR.jpg

 

Leaving this hollow structure which still had a hole in the base. 

wA14lRP.jpg

 

I added a bit of internal reinforcing plastic and then used a small sheet of lithoplate to close off the open end.  Lithoplate is very thin so it leaves a sharp edge between different facets of the model. This makes for a tidy 'manufactured-looking' edge.

PdL8K0g.jpg

 

Any of the rougher joints get a bit of filler applied which then gets sanded back.

 

Once temporarily stuck in position with a lump of blue-tack, the telescope mount looks like this, which I think is encouraging.

4aRuNop.jpg

 

But when viewed from this angle I've decided I'm not happy with the join between the main solar sail and the sail boom. 

eNDmYd3.jpg

That cunning plan we discussed above will be the next post. I wonder if it will work! 🤔

 

Best Regards,

Bandsaw Steve

 

 

  • Like 20
Link to comment
Share on other sites

16 hours ago, Bandsaw Steve said:

Note also the medical lance / needle at the top of this photo. These are can be bought for very little at any pharmacy and are intended for popping pimples, however I've found that these are extremely useful for a number of modelling tasks including:

  • Holding and maneuvering very small plastic pieces.  Just very gently stab any piece of plastic and it will be very securely held on the spike.
  • Making very precise mark-ups on plastic sheet. A pin-hole is much more precise than a pencil mark.
  • Scribing or making very detailed, precise cuts in plastic, especially since I've found that a sharp point like this tends to wander less than a blade.

Gidday Steve, I'll have to look into one of those. As for razor blade vs scalpel, I find that they both have their advantages.

 

I REALLY like that telescope mount, it looks very authentic. Regards, Jeff.

  • Thanks 1
Link to comment
Share on other sites

15 hours ago, ArnoldAmbrose said:

Gidday Steve, I'll have to look into one of those. As for razor blade vs scalpel, I find that they both have their advantages.

 


Indeed they do, but I find myself using the classic, triangular, super-pointy #11 scalpel blade less & less these days. On the other hand,  for me the main drawback with a razor-blade seems to be that they aren’t especially comfortable to hold for any length of time, I’m very sensitive like that. 😮‍💨
 

Maybe I need to fashion a handle for the blades.

Link to comment
Share on other sites

31 minutes ago, Bandsaw Steve said:

Maybe I need to fashion a handle for the blades.

Try a cleaning supplier. In cleaning jargon they're called scraper blades and a handle is available to hold them. Google 'window scraper tool'. HTH. Regard, Jeff.

  • Thanks 1
Link to comment
Share on other sites

Really clever work, the telescope looks amazing. Love the way you developed the shape from flat sheet. As if that wasn't cunning enough we have a cunning plan update to follow. :)

 

 

Richie

  • Thanks 1
Link to comment
Share on other sites

The telescope mount looks brilliant, and very thoroughly described how you got there! I tend to get to the end of a particular assembly and then realise I've not taken any photos along the way...

 

Keep up the great work!

 

Mike 

  • Thanks 1
Link to comment
Share on other sites

A Cunning Plan

 

As promised, here's a mildly cunning plan to replace the  solid & continuous block of material between the solar sail boom and the sail with something a bit more realistic.

eNDmYd3.jpg

 

In the drawings below you can see that there is a gap between the solar sail and the sail's boom, which is partially filled with a network of fine 'scafolding' that holds the sail lightly in place. Currently my model does not have this gap and I've decided it needs to be there. Although I'm confident that very few would know this was an error I think that leaving this area solid makes the construction look 'heavy' and 'terrestrial'. I think that modelling this gap will enhance the impression of lightweight construction and will add to the visual 'feel' of delicacy and authenticity about the model. As @hendie might say - 'without these details folks might feel the model was not quite right even though they would not know why'.  

 

AcRGjpN.jpg

And so to the so-called 'cunning plan' to make the solar sail 'float' clear of the boom.

 

First, mark up three slots on the existing sail structure, each lined up with one of the carbon-fibre rods that will take the weight of the sail.

PgUhQpL.jpg

 

Cut the slots as shown and shorten the rods to fit into them. Glue the solar sail onto the three rods using two-part epoxy, this is now reasonably strong despite the significant gap left between the boom and the sail.

Nr2Pn9W.jpg

 

Use normal model building cement to attach a series of 'important-looking' rods and beams into the gap. Note that none of these are  structural at all - they aren't even glued onto the beam - but they look like they are holding the sail in place, and that's all that's important.

2zEwAW9.jpg

 

Now cut out three rectangles of aluminum litho-plate, each the same size as one of the solar panels.

502zCBA.jpg

 

Now use cyanoacrylate to simply glue them onto the top of each panel so that central slot and carbon-fibre rod are both concealed. Repeat the process on the underside so that the carbon-fibre structure is hidden from all angles.

 kFEnNuu.jpg

 

Add a length of plastic to tidy up the area where the new rods and beams join the sail and to conceal the fact that the three panels are actually joined at the root. (On the real Skylab they were completely separate units).

tSPfpox.jpg

 

Here's the result. I'm happy with this, although if I was doing it again I would be tempted to make some of the small white beams a bit thinner. 

07FrC5m.jpg

 

So that's the cunning plan successfully executed.

 

In the usual course of events that's about as cunning as I get but the next step might test me further.  It's time to have a look at the big X shaped solar panel array surrounding the telescope. I'm anticipating that this will be one of the two most challenging parts of this entire project.  I expect this is going to test me out. 🤔

 

Best Regards,

Bandsaw Steve 

 

 

 

  • Like 10
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...