Perhaps they could revisit the original parafoil proposal vs the chutes...
Won't the volume of the parachutes and parafoil be more or less the same?
Are there any pictures of what the Original Orion capsule would have looked liked?
I believe that the Orion here is 5.5m, though I could be wrong. Note the SM dia. = CM dia. (From Astronautix)
This gives a good comparison of the Apollo CM with the 5.0m Orion CM
Thank you, I know about the diameter of the Orion being built now compared to Apollo but do you or anyone else know what the height of the Orion will be? Will the Orion be taller, same height or smaller than the Apollo capsule?
Thank you, I know about the diameter of the Orion being built now compared to Apollo but do you or anyone else know what the height of the Orion will be? Will the Orion be taller, same height or smaller than the Apollo capsule?
It has the same ratio as Apollo. That is why the shape was chosen. It didn't need any wind tunnel testing because it uses the Apollo shape.
Thank you, I know about the diameter of the Orion being built now compared to Apollo but do you or anyone else know what the height of the Orion will be? Will the Orion be taller, same height or smaller than the Apollo capsule?
It has the same ratio as Apollo. That is why the shape was chosen. It didn't need any wind tunnel testing because it uses the Apollo shape.
I remember a news interview on television right after the Orion shape was announced. I do not remember whether it was with Griffin or one of the Orion designers. I am 99% sure I remember this correctly. The person being interviewed indicated they had run aerodynamic tests (and I thought that included wind tunnel testing-but perhaps it was only computer modeling) for the Orion shape and determined it to be the safest. The interviewee concluded by saying they were all amazed that the Apollo designers had come to the exact same conclusion and had chosen the same shape all those decades before.
Edit: In this picture from Marshall, the capsule does not seem to have the same proportions. It even seems triconical:
My guess is the capsule itself had to have this design tweak to accommodate the aerodynamic shroud placed on the bottom of the LAS? Nevertheless, reentry aerodynamics would differ, correct?
As I look at the Orion and Apollo above, if the cones continued to their vertices, the Apollo vertex would be slightly more acute. The vertex in the parachute drop Orion here seems that it would be almost slightly obtuse.
The person being interviewed indicated they had run aerodynamic tests (and I thought that included wind tunnel testing-but perhaps it was only computer modeling) for the Orion shape and determined it to be the safest. The interviewee concluded by saying they were all amazed that the Apollo designers had come to the exact same conclusion and had chosen the same shape all those decades before.
I'd like to know why it is the "safest". The Soyuz shape was safe enough to go around the Moon and back, and has much better volumetric efficiency due to the higher side walls. The Chinese will also be using the same Soyuz shape for their Lunar missions, if that program ever gets the go ahead.
Edit: In this picture from Marshall, the capsule does not seem to have the same proportions. It even seems triconical:
Yes, the capsule shape in these parachute tests was "squashed" so that it would fit inside the C-17 carrier aircraft.
Thank you, I know about the diameter of the Orion being built now compared to Apollo but do you or anyone else know what the height of the Orion will be? Will the Orion be taller, same height or smaller than the Apollo capsule?
The Orion capsule is taller than the Apollo Command Module, as you can see in the image on the previous page. I estimate the Orion capsule height to be 3.45 m.
Edit: In this picture from Marshall, the capsule does not seem to have the same proportions. It even seems triconical:
That is a parachute test vehicle and not Orion
I'd like to know why it is the "safest". The Soyuz shape was safe enough to go around the Moon and back, and has much better volumetric efficiency due to the higher side walls. The Chinese will also be using the same Soyuz shape for their Lunar missions, if that program ever gets the go ahead.
But there must be some advantage to the Apollo/Orion shape. Lower g-forces, increased landing accuracy?
Yes, the capsule shape in these parachute tests was "squashed" so that it would fit inside the C-17 carrier aircraft.
That's a shame, because it looks kind of cool
But there must be some advantage to the Apollo/Orion shape. Lower g-forces, increased landing accuracy?
Because little research was needed to use it, they leveraged Apollo data
But there must be some advantage to the Apollo/Orion shape. Lower g-forces, increased landing accuracy?
Because little research was needed to use it, they leveraged Apollo data
I have a hard time believing that making the side walls steeper/higher would have had a big impact on development costs. I mean, its not exactly the most complex reentry shape out there...
I have a hard time believing that making the side walls steeper/higher would have had a big impact on development costs. I mean, its not exactly the most complex reentry shape out there...
There is no entry test data other shapes at lunar or Mars return velocities.
I have a hard time believing that making the side walls steeper/higher would have had a big impact on development costs. I mean, its not exactly the most complex reentry shape out there...
There is no entry test data other shapes at lunar or Mars return velocities.
Shouldn't the Russians have Zond data?
All right, I've done some reading.
So it basically went like this (at least according to that ESAS report I found).
-> They started with 5.5m diameter and 20° aft-body sidewall angle.
-> Volume not needed, too heavy (aft-body TPS, radiation shielding etc.), aft-body flow impingment (whatever that is), desired L/D and monostability at the same time not achieved.
-> Next proposal was 5.2m diameter and 30° sidewall angle.
-> Packaging and mass issues (among other things they did not want to stack crew members).
-> Final proposal 5.5m diameter and 32.5° sidewall angle. Benefit of aerodynamics and aerothermodynamics well known from Apollo.
The relevant sections of the report (attached).
5.3.1.3.3 Initial Axisymmetric Capsule Shape Downselect
In order to balance the effects of the changing parameters, a baseline vehicle was selected with
a shallower cone angle of 20 deg (since this had the least effect on other parameters), with the
same base and corner radius as Apollo. This new vehicle trended toward the family of vehicles
represented by the Soyuz capsule, which has an even shallower sidewall angle. This vehicle
is shown in Figure 5-30 below. It was estimated that an achievable X-axis center of gravity
(Xcg ) position would lie at or around the 45 percent volume level. In that case, the Zcg offset
required for 0.4 L/D would be roughly 0.053 times the diameter. For this shape, the monostable
CG position could be as high as the 48.6 percent volume level, which would therefore leave
some margin for assured monostability.
5.3.1.3.5 Initial Capsule Shape Trade Conclusions
For the initial capsule shape trade study, detailed and extensive analysis of parametric effects
and trends of various capsule shapes and features indicated that achieving the desired characteristics
was indeed a formidable task. A compromise was made to achieve all of the desired
characteristics as closely as possible while minimizing the detrimental effects. The resultant
axisymmetric shape (shown in Figures 5-30 and 5-32) was a 5.5-m diameter capsule with
Apollo heat shield and 20-deg aft-body sidewall angle. The capsule offered large volume
(i.e., large enough for surface-direct missions), easily developed axisymmetric shape, the best
chance for monostability, L/D = 0.4 with attainable CG, adequate static stability, and low L/D
sensitivity to CG dispersions. Nonaxisymmetric shape optimization had shown that this technique
could indeed reduce CG offset requirements if needed in the future. Further detailed
analysis was then required to further define the performance characteristics of the axisymmetric
shape.
5.3.1.3.11 Alternate Proposed CM Shapes
Near the end of the ESAS, it was decided that the direct-to-surface lunar mission architecture
would not be prudent. This eliminated the need for a high-volume CEV CM such as the
baseline axisymmetric CM shape. In addition, a 1.5-launch solution was selected in which the
CEV CM would always be launched on a Shuttle-derived CLV configuration for both LEO
and lunar missions. This LV was limited in performance, particularly for the lunar mission
and lunar CEV, which created a need to decrease the baseline CEV mass. Because significant
mass was created by the extremely large aft-body due to TPS, radiation shielding, and
structure, it was desirable to increase the aft-body sidewall angle. In addition, the aft-body
flow impingement of the baseline axisymmetric CM shape was not desirable. Finally, the
systems packaging at this point had still not achieved the desired CG location for the baseline
shape. Although the CG location was low enough to provide monostability, it was not
offset far enough to produce the desired 0.4 L/D ratio. All of these factors weighed in against
the remaining benefit of the shallow-walled, large aft-body baseline design—the potential
monostability. Eventually, the desire for aerodynamic monostability was outweighed by other
factors; however, other propulsive or mechanical methods are available to ensure stable ballistic
entry, such as employing a flap or RCS jets.
The baseline axisymmetric shape was modified to have a 30-deg back-shell sidewall angle
and reduced diameter to 5.2 m. This provided a 2- to 3-deg buffer from the flow direction at a
26–27 trim degree angle-of-attack. The alternative AFE-type vehicle with its 28-deg sidewall
angle was already suitable, except for the fact that it was scaled down to a 5.2-m diameter. In
addition, its length was decreased to allow for the docking ring diameter and a tighter corner
radius was employed to help decrease the Zcg offset requirement. Both changes to the AFEtype
shape significantly decreased monostability. These vehicles are shown in Figure 5-42.
The Cm curves for these vehicles are shown in Figure 5-43 at the representative CG locations and
monostable limits. The Cm curves are similar, although there is a slight reduction in static stability
at the desired trim angle-of-attack of the AFE-type shape compared to Apollo. Figure 5-44
provides the 0.4 L/D CG trim lines for these configurations. (Note: the significantly reduced Zcg
offset requirements of the AFE-type shape.) Both trim lines have roughly equal distance from
a representative CG to the monostable CG limit. Table 5-18 presents some performance specifications
for the two vehicles. The overwhelming benefit of the AFE-type configuration is the
reduced Zcg offset required for 0.4 L/D, though there is a slight TPS mass cost.
5.3.1.3.12 Final ESAS CM Shape
Based primarily on packaging and mass issues, the final proposed baseline CEV CM shape
was a 5.5-m diameter Apollo (with the original Apollo 32.5-deg sidewall). Thus, the aerodynamics
and aerothermodynamics are well known. TPS estimates were made based on the
results presented previously using the heat shield data for the axisymmetric baseline shape and
the back-shell data for the AFE-type shape. The trimline for this shape was found to be nearly
identical to that shown previously for the 30-deg sidewall Apollo. Also, the ballistic entry
analyses provided above is still applicable for the most part.
Concern is warranted, however, over the ability to achieve the Zcg offset that will be required
to achieve a 0.4 L/D using this shape. However, the alternative AFE-type shape as shown
previously would alleviate this concern. The shape working group is continuing to evolve an
AFE-type shape that is directly comparable to the proposed 5.5-m diameter Apollo with a
32.5-deg back-shell, with the only difference being in the heat shield shape. Further risk and
performance analyses in the areas of landing (land versus water) may ultimately determine
which CEV CM shape is selected.
Here are some photos of my 1/72 Apollo 7 (Dragon pre-built model) and two Fantastic Plastic Orions, 1 early and 1 Late (but before the ESA Delivered SM concept.)
First some Apollo - "Big Orion Comparisons
Apollo Vs Little Orion (with old style Solar Panels. 1 has broken off and I couldn't find where I stored it to make sure I could repair it.)
Old and New Orion (note the warping on the long solar cells. One day I will get around to replacing them.)
Then all three together. Note the Big Orion has a smaller nozzle than the Small Orion. That was, I think, from when it would have a methane-oxygen engine.
And then, for fun, Orion with the Japanese Resupply Vehicle and Dream Chaser. The Resupply vehicle is said to be a little underscale.
O.K. Mike, you just put me into a really nostalgic mood for the room full of model rockets and planes I had as a kid. I'm having flashbacks and increased heart rate! You also made me realize what I might spend a lot of time doing when I retire in 3 years too!
Sorry for being OT, just got so space geek excited. Hope the mods can understand and forgive a guy for that..
(BTW, where did you find the kits for those?)
