FINAL INDEPENDENT PROJECT

MODELLING AND ASSEMBLY OF SATURN V ROCKET USING SOLIDWORKS

Objective

The objective of the project is to design the parts of the Saturn V rocket using Solidworks software and assembling it in an assembly file. For designing the parts, images from the internet are taken as a reference. The images constitute any existing dimensions from old blueprints, photographs taken of the actual rocket as well as museum models, computer generated models and of section views for interior designing. The details to each part are given as close as possible to showcase realism. The completed parts are assembled. An exploded view is also to be given to the assembly to show the staging sequence of the rocket.

Design Procedure

1.S-IC (Stage 1)

i) F1 Engine

The first part which is modelled is the main engine of the first stage, i.e the F1 engine. The overall dimension (maximum height and width) for the engine is obtained. First the nozzle of the engine with the support rings are sketched and revolved to form the base of the rocket.

Then the components resting above the nozzle are made by approximating the dimensions and by comparing with the images available online. Visually distinct parts such as the larger pipelines and heat exchanger are designed. For the heat exchanger, the dimensions are assumed and designed around the cone. It is made by first using swept sections of varying cross sections and then mirrored. Inlet to the heat exchanger is designed above the swept sections. Then pipes of significant size are modelled to resemble the original photos as close as possible. The complete F1 Engine model is shown in figure below.

Since the actual rocket had 5 engines, the original model is first given a linear pattern of one instance, and the resultant instance is given a circular pattern around the main design.

ii) Main body

After the engines, the main body of the stage is modelled on top of the engines. The hollow body of 10 metres external diameter and thickness of 0.25 metre is extruded to the length of the stage given in official sources. Body is kept hollow to design the internal tanks. Following this, the external features on the tank are designed, such as the vents. The vent is designed by giving an arbitrary cross section and then extruding it to a rough distance. Then it is fileted at the end and given a circular pattern of 100 instances all around the body. Subsequent parts where the vents appear are also given 100 instances unless changes are needed.

Four cones, each at an engine location is made for accommodating the engines. The four fins are designed on the cones using rough dimensions. The engine coverings are basically a partial extension to the cones, denoted by grey colour in figure below. Then the outer surfaces are split using split line feature. This is done to assign the appearances to the outer features, which represent the paint used on the actual rocket. Black and white appearances are assigned to specific surfaces.

This completes the external features of the stage. A render is created in Solidworks Visualize to add realism to the body.

ii) Internal Features

The internal features consist of the internal tanks, the pipelines and support structure. First the lower tank (RP-1 propellant tank) is designed by creating a separate body using revolve feature on a sketch and then giving a shell to it of 1 centimetre. Similarly the upper tank (liquid oxygen tank) is designed. A central pipe is designed which begins from the upper tank and ends at the centre engine. Four other pipes branch out from the main pipe at the bottom to the outboard engines. Pipes from the lower tank are connected to the branched pipes to feed the propellant. The pipes are designed by first using a solid sweep and then a cut sweep of a smaller diameter but the same profile used for the solid sweep. The support structure is designed at one place and then revolved.

The section view is also rendered in Solidworks Visualize to show the internal features such as the tanks, structures and the pipeline in detail. Appearances are also assigned to them. The black and white colours represent the lead paint used for the original rocket.

This completes the modelling of S-IC (Stage 1).

2. Stage Separator 1 (Between Stage 1 and 2)

In the previous stage, an offset surface of 0 metre offset is given to the top of Stage 1. This is hidden in the part file of the stage. The surface is then imported separately to a new part file. Here the surface is projected onto a plane using convert entities. The new sketch is extruded to a certain distance, such that Stages 1 and 2 would as close as possible to each other. Surfaces are split to assign the appearances of alternating black and white faces on the external surface of the body. The part was rendered in Visualize.

3. S-II (Stage 2)

i) J2 Engine

Similar to the previous stage, this stage is also designed bottom up, starting with the engines. First the engine cone and its rings are designed using the available height and diameter. The heat exchanger is also designed for one half around the engine cone and then mirrored for the other half. The rest of the features, such as the pipes and smaller chambers are designed using estimations and visual comparisons with the existing images of the real engine or with computer rendered images. The appearances are also assigned to the parts to resemble the real components as close as possible. Like the previous stage, the second stage also consisted of five engines, with four surrounding the central engine. By keeping the modelled engine at the centre, a copy of the engine is made using linear pattern and the resultant is given a circular pattern around the modelled one, in the same way it was done for the previous engine. Also, Stage 3 has the same engine as Stage 2, but only a single engine. Hence the modelled engine is saved in another part file for modelling Stage 3 later.

ii) Main body

This was created using a revolved frustum first and then the revolved cylinder above it, with the cylinder matching the diameter and thickness of the Stage 1 and Separator 1. The same procedure is followed regarding the design of external features from the previous stage, such as the vents and external pipes. The surfaces were split and the appearances were assigned accordingly. The part was also rendered in Visualize.

ii) Internal Features

In this stage, the tanks are designed different from the previous stage. Because unlike two separate tanks in Stage 1, this stage has two conjoined tanks, with both tanks separated by a common bulkhead to separate the contents of the upper (liquid hydrogen) and lower (liquid oxygen) tanks. For designing such a tank, first a separate solid is made revolving the profile. Here the profile is of the entire length of the tank. The resultant solid is then hollowed out. The bulkhead profile of 1 cm thickness is then drawn and revolved. The tank is visible in the section view of the stage.

4. Stage Separator 2 (Between Stage 2 and 3)

For designing this part, the offset surface from Stage 1 is imported into the part file and its sketch is projected onto a plane. Unlike the previous Separator, this part has a varying cross section, so the individual vents on the surface of this part will also vary in cross section. Since the diameter reduces from 10 m to 6.6 m, the vent cross section for reduced proportionately, and drawn on another plane offset from the original plane. The resultant sketches are lofted to create the outer surface. A lofted cut is made through the middle to give the part a ring like form. The surface was split to assign the appearances.

5. S-IVB (Stage 3)

i) J2 Engine

Since the same engine is used in this stage as in the previous stage, the engine is saved in another part file. This part file is opened and the body design can be started above the engine. This stage has only one engine.

ii) Main body

The body is started from the top of the engine, using a revolved profile to create a conical surface. The height of the cone was estimated. Following this procedure, the main body was created, with a diameter of 6.6 m and 0.25 m thickness. Helium tanks (spherical tanks on the conical surface) were then created using circular pattern. Two external pipes were also designed for this stage, which starts from the upper tank (liquid hydrogen) and ends at the engines. First a single pipe was swept using a path and profile and then using a swept cut using the same path but a smaller circular profile. The pipe was then mirrored across a custom plane. The vents were designed using the Stage Separator 2 vent cross section as reference. Vents were skipped at two instances where the pipes are passing. Surfaces were split using the split line operation for assigning the appearances.

ii) Internal Features

The internal features designed for this stage are the tanks, support structure and one internal pipeline. The tanks are designed in the same way as that done for Stage 2, i.e. two tanks with a common bulkhead. The single tank profile is revolved to create a separate solid and then hollowed out using shell feature. The common bulkhead is sketched and then revolved to split the tank. A single pipeline is made between the bottom of the lower tank (liquid oxygen). Support structures are designed internally along the pipe.

6. Instrument Unit (IU)

This is a cosmetic model made just to represent the Instrument section placed above Stage 3. In reality it was integral with Stage 3. The computers were placed within the inner surface, represented by a green colour in this model.

7. Lunar Module (Descent Stage)

i) Main body

The lunar module consisted of a descent and ascent stage. The decent stage was used to land on the surface of the moon, whereas the ascent stage was used to launch from the surface to dock back with the orbiter after the exploration had been completed. For modelling the descent stage, the rough dimensions are first obtained. The part is a regular octagon when viewed from top. The octagon is sketched and extruded downwards. Next the landing legs are modelled in the folded position. It is done so that the model fits within the rocket. First the four supports (in black and grey) and the hinge are modelled. From the hinge, the legs are modelled using the revolved profile downwards and inwards. The hinge at the foot, connecting pin, the landing pad and lower support structures (in gold) are also designed at the bottom. The legs, hinges and support are then given a circular pattern around the solid to give a total of four legs. A ladder is modelled on one of the legs. Appropriate appearances are given for the surfaces. In this part, the gold colour represents the gold foil wrapped on the spacecraft.

ii) Internal Features

Like the stages modelled previously, internal features are modelled for this part too. The features modelled are the segments containing the Fuel and oxidizer tanks, helium tank, pipelines and the engine plus combustion chamber. First the segments are sketched and the cut into the solid from the top. The oxygen tanks (green) and fuel tanks (brown) are then modelled as separate solids and then shelled. The central combustion engine and the engine nozzle are modelled next. Following this, the pipelines are made for feeding the oxidiser and fuel into the combustion chamber. The pipes are first modelled as a solid sweep, and then hollowed out using cut sweep. An extra helium tank is also modelled at one of the corner segments. After the completion of the internal modelling, a thin extrude is made on top of the components, covering them entirely. This completes the Decent Stage modelling.

8. Lunar Module (Ascent Stage)

The ascent stage, unlike any other part modelled, has no fixed shape. The original stage flown to the moon was just made of metallic foil wrappings on a lightweight skeleton to reduce weight. Because of this, the stage has a random shape and becomes difficult to model by just visual comparisons. So instead of modelling the entire stage and then adding the details later as done with the previous stages, this stage was modelled externally as well as internally section wise, starting from the front, and going to the back. The internals (crew cabin) were completed first and then external features were added.

The modelling is started with an extrusion of 1.4 m, given to a circle like profile with a flat bottom. This profile is roughly visible in the actual spacecraft when seen from front. Then a sketch is drawn on the back of the extrusion. This sketch roughly depicts the cabin profile (side walls). An extruded cut is made through the solid to create the front portion of the cabin. The triangular windows and front hatch are shown using the split line command. The split is made on both the interior and exterior surfaces. Some extrusions are made on the external front face to depict the features.

After the Front half is completed, the rear half profile is drawn and extruded 1.4 metres.

Next, the Oxidiser tank is modelled on the right side of the spacecraft (when viewed from the front). The tank profile is drawn and revolved. Four support structures are joined from the tank to the main body. Then the casing is provided for the tank by extruding and loft features.

The same procedure is followed for the fuel tank on the opposite side of the spacecraft. After the completion of the tanks, the main engine and its casing were modelled within the cabin. The fuel lines were also modelled; one from each tank to the combustion chamber. Some cabin aesthetics were also modelled in the rear half. This completes the internal features.

After the completion of the internal features, the cabin is covered with a thin extrude and the last external features are modelled. The electronics bay, the rear oxygen tank and the covering for both are designed. Then the thrusters at each corner of the spacecraft are designed. The thrusters are essential in turning the spacecraft in space. The final appearances are assigned to the internal and external surfaces. This completes the modelling of the Ascent stage. The part is also rendered in Visualize.

9. Command Service Module (Command Module)

The command service module is a two-part spacecraft, just like the lunar module. It was also known as the orbiter, since it orbited the moon while the lunar module landed on the moon and returned back. The orbiter consists of a Command module and a Service module. The Command module was the main cabin of the spacecraft, where the astronauts resided during the entire mission. It was the only component of the Saturn V which safely returned back to earth after re-entering the atmosphere.

The standard dimensions of the spacecraft were first taken into consideration, such as the height, diameter and the half cone angle, since the spacecraft was conical in shape. The profile was sketched and revolved to create a hollow cone with a rounded bottom. The surface details, such as the main windows, side windows and front hatch were shown using split surfaces. The interior was designed to include a computer panel at the top of the spacecraft, a docking tunnel was cut for crew transfer between spacecrafts and three seats on the floor. The docking hatch was made at the top of the cone, depicted by a dark grey appearance. The necessary appearances were assigned to the components at both the interior and the exterior surfaces. The bottom curved surface (heat shield) is given an offset surface of 0 metres. This surface will be used in the modelling of the Service Module. The same is done for the conical surface, which will be used in modelling the Launch Escape Tower. This completes the Command Module modelling.

10. Command Service Module (Service Module)

The Service Module was an auxiliary unit to the command module. It housed the necessary items such as oxygen and water for the crew. It was also essential for propulsion and maneuvering of the spacecraft in space.

The offset surface of the heat shield from the Command Module is imported to a new part file. This surface represents the top of the Service Module. The service module is modelled below the imported surface to create the body and main engine nozzle. White bands and two cargo doors were added on using split surface. The four thrusters, used for accurate maneuvering, were modelled on the external surface of the body. The internal features are the storage tanks, located within sectors. First the sectors were cut into the body, followed by seven tanks (one for each sector). The appearances were assigned as required to complete the modelling of the Service Module.

11. Launch Escape Tower

The Launch Escape Tower was a component mounted above the Command module during launch. It was to be used only during an emergency situation during Stage 1 burn only. In case of an emergency, the Launch Escape Tower would pull the Command module from the rest of the rocket using rockets of its own. Otherwise in normal conditions, it will fly away from the rocket on its own after Stage 1 is exhausted.

The conical offset surface made during the command module modelling is imported into a new part file. Using this imported surface as a reference, the outer covering is modelled using a revolved profile. Above this revolve, the structure for the rocket tower is made by visual comparisons with the images online. Four rocket nozzles and an internal fuel tank for the rockets were modelled in the end. Appearances were assigned to the surfaces, completing the modelling of the Launch Escape Tower.

12. Payload Fairing

This is the last component designed for the assembly. It lies above the Instrument Unit and below the Service Module, and houses the Lunar Module. This component is modelled last because of its ease in adjusting the dimensions so that the tolerance between the engine nozzle of the Service Module and the top of the Lunar module is kept as low as possible.

First the external diameter of the Service module and the Instrument units are noted so that the fairing remains flush with both their external surfaces. Comparing the images online, a rough sketch for the outer surface is made using an estimated height. A 5 cm offset is given inwards to give the thickness of the component. The sketch is then closed. A reference axis is drawn for revolving the sketch. Since there were four fairings surrounding the Lunar Module, a 90º revolve was given to it. During the assembly, the same part is called four times to enclose the Lunar Module.

This completes the modelling part of the Saturn V Rocket.

13. Assembly of the Saturn V Rocket

Once the modelling is completed, the parts are assembled in the Solidworks assembly file. The following steps are followed for the assembly procedure:

• The first part imported is Stage 1. It is placed automatically within the file when called and so it snaps to the origin point within the file.
• Next the Stage Separator 1 is called within the file. It is first placed in an arbitrary position. Then it is aligned with the first part by mating the central axis and then their surfaces to join the parts. The vent edges on both parts are aligned by mating, so that they are flush.
• Stage 2 is brought next. Like the previous part, the axis is aligned first and then the surface at the bottom of the body of Stage 2 is mated with the upper surface of the Separator. Their vent edges are also aligned.
• Stage Separator 2 is also brought in and aligned like in the previous steps.
• Stage 3 is brought in and placed above Separator 2, and aligned with its vents.
• The Instrument Unit is first aligned with the axis of the rocket and then mated on top of Stage 3.
• The Descent Stage is placed next. It is first aligned with the central axis of the rocket. Then it was manually lowered into the upper portion of Stage 3. It is placed in such a way that the landing legs are at a small distance away from the Hydrogen tank of Stage 3.
• The Ascent Stage is brought in. Since it has no central axis, it is aligned by taking the side surfaces of the Descent Stage as the references and giving certain value of offset distances. It is also aligned in such a way that the front hatch of the Ascent Stage faces the ladder of the Descent Stage. The bottom of the Ascent Stage is then mated with the upper surface of the Descent Stage.
• The fairings are brought in next. Since there are four fairings in the original rocket, a single fairing is modelled and called in four times. First the bottom surfaces of the fairings are mated with the top surface of the Instrument Unit. Then the internal surface of the fairing is aligned with that of the Instrument Unit, using concentric relation. The following fairings are then mated with the side surfaces of the pre-positioned ones, to enclose the Lunar Module.
• The Service Module is place above the fairings by mating the lower surface of the Service to the upper surface of the fairings. The Service Module is also aligned axially.
• The Command Module is aligned axially first. Then it is lowered manually to mate with the upper surface of the Service Module. Direct mate of surfaces is not possible, since the surfaces are curved.
• The Launch Escape Tower is places last, right above the Command Module. This completes the Assembly of the Saturn V Rocket.
• The assembly is then rendered in Solidworks Visualize, using appropriate lightings and scenery to create a photorealistic image.
• Within the assembly file, a section view can also be made to show the internals of all components together. An exploded view is also animated to show the sequence of staging which occurred with the real rocket.

Conclusion

The Saturn V Rocket was successfully modelled and assembled in Solidworks. The assembly and some of the individual parts were also rendered to create realistic images using Solidworks Visualize. This model can be further improved by adding even smaller details to add more realism. The model can also be used for various analysis tools, such as aerodynamics and atmospheric drag. It can also be studied for effects of temperature during re-entry, as well as improving its design for long term space travel. Similarly, rocket engines can also analysed for inflight stresses, thermal fluctuations and tolerances, structural rigidity etc. The lunar module can also be considered for redesigning for future space explorations on extraterrestrial planets like Mars.