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Old 03-15-2018, 06:12 AM
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1/24 thrust structure very nearly finished

Dear all

I was intending to post the finishing of the 1/24 thrust structure by completion of the the fairing internal strut supports. However I realised (after saying in my previous post this is what would happen) that I still needed to do the the gimbal actuators for the F-1 engines (parts 37 a,b,c of the F-1 engine parts) and this needed to be done before completing the struts.

Because I needed to make the F-1 engines removable this naturally meant that the gimbal actuator had to be removable. I decided to make them detach at the support structure point inside the fairing. However this idea raised a problem, which is, it is very unlikely that you can keep putting the F-1 engines back in exactly the same position, so the gimbal actuators needed to be adjustable in length. Also the gimbal outrigger arms on the F-1 engine are not all exactly aligned the same so the gimbal actuators needed to be adjustable at this point also. Finally I wanted to be able to place any F-1 engine in any of the 5 positions on the base of the thrust structure.

After a lot of thought I thought I had a good solution by making self adjusting paper spring loaded gimbal actuators. The paper springs worked well but the size of the housing (part 37 b) meant the final result was a little floppy for my taste. However from this came the idea that I ended up doing.

The method meant that the centre engine was done slightly different to the four outer engines. Since this is not as in the instructions I will detail what I did. First for an outer engine.

The parts for a gimbal actuator are 37 a,b and c as shown

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12262.jpg

Cut out, and notice I have added a tab on part c (see photo below)

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12263.jpg

I cut out a "square" of magnetic sheet (self adhesive) and stuck it on the "gluing point" of part c (where c would glue to the strut in the fairing). Then fold and glue c (shown below). Notice the added tab is NOT glued

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12264.jpg

Fold but do not glue the added tab (as shown). This means the "angle" of the foot can be adjusted (the added tab means that it will not "pop out").

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12265.jpg

Fold and glue parts a and b (shown below)

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12266.jpg

Next I took a paper lollipop stick of diameter 4mm and cut off a length of 5 cm (alternative make a strong paper tube).

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12267.jpg

Then I glued the stick inside part 37 a (as far in as possible without poking out the other end)

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12268.jpg

After this I tried sliding part 37 c (the red part) on the other end on the stick. I wanted a "good", not too tight, not too loose. Just tight enough that it would hold its position but also that it could be adjusted easily. This is a bit variable (for each of the ten times you have to do it for the model) so may require putting a layer of paper around the stick of a certain thickness to get the right fit (see below)

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12269.jpg

Next part b was glued to part a on one side only. Notice the orientation of the "prongs" of part a relative to the glued part a/part b connection. (You need to remember to do all 10 of these the same for the model)

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12271.jpg 1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12270.jpg

Slide part c (the red part) onto the other end of the stick. You now have a telescopic gimal actuator which you can adjust the angle of the "foot" and also rotate 360 degree

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12272.jpg

I decided to attach the gimbal actuator to the gimbal outrigger arm link a link in a (slightly worn) bicycle chain. So first I made the "pin" by cutting a 4mm length from the stem of a cotton bud. I wanted it to be made of paper so I used Johnson's cotton buds since they are still made this way (most cotton buds have plastic stems now)

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12232.jpg 1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12222.jpg

Then I drilled a hole (slightly larger than the diameter of the "pin") through the gluing point of the gimbal outrigger arm. I simply twisted the drill between my finger and thumb. However I did use three drills, so gently opening up the hole to the correct size

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12230.jpg 1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12231.jpg

I then place the "pin" in the hole and then glued the prongs of the gimbal actuator to the ends of the "pin", making sure that the "pin" did NOT glue to the gimbal outrigger arm (also making sure that the gimbal actuator was round the correct way. I found the best way to ensure this was to glue with the engine placed as if it was on the botton of the thrust structure). See photo below

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12273.jpg

For the centre engine the only differences are you need to remove some tabs from parts 37 a and 37 c (as shown below) and the lollipop stick is only 3.5cm long.

1/24 Apollo/Saturn V (enlarged 1/48 Greelt et al version)-sdc12279.jpg

continued in my next post...

Kevin
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