Why does the Gemini have a flat nose cone and no escape tower

[Kryten]

Ejection seats would also have been used if they ended up re-entering over land, given absence of any kind of shock cushioning features on gemini.

[Capt. Hunt]

20 hours ago, Nibb31 said:

Nobody ever pretended it was better. Instead of a LES, the astronauts had ejection seats, which were of dubious use, because an ejection would only have been survivable at rather short altitude range.

Remember that the Gemini program was actually started as a quick and dirty crash program after Apollo. When the Apollo program was kicked off, NASA knew that there would be a several year gap before the first flight. The plan was for Gemini to a cheap test platform for developing EVA, rendez-vous, docking, and long duration techniques, as well as to train new astronauts for Apollo. The lack of a launch escape tower was the result of engineering compromises (mostly weight) and low cost.

The flat nose cone was the docking system, including a radar, sensors, and a docking mechanism.

Also, IIRC the Astronauts wanted the capsule to be more "airplane like," which apparently included ejection seats.  While it probably wouldn't have worked off the pad, the capsule's retro rockets had enough delta-v to act as a LES by the time the vehicle exceeded the max altitude for safe ejection.  There were plans to add a LES tower for the Big-G.

Edited April 13, 2017 by Capt. Hunt

[wumpus]

22 hours ago, Nibb31 said:

That's right. This is the Titan II warhead.

(ever so much like a Gemini capsule)

Every time it comes up, all available information* states that [US] warheads come down pointy end down.  I've always been skeptical, but I suspect that having the same aerodynamic characteristics going up simplifies things enough to reuse the envelope.

* I really don't think that the US military gave the artists who make the various animations more than they "needed to know".  That likely includes which way the warhead was facing coming down.  But "pointy end down" certainly makes any defense much harder, and lowers the potential for fratricide.

[Kryten]

Only a few early missile warheads used capsule-esque 'blunt body' designs-they're vulnerable to interception because they come down so slowly, and they're particularly visible to radar. Even scud warheads come in 'pointy end down'.

[sevenperforce]

8 minutes ago, wumpus said:

Every time it comes up, all available information* states that [US] warheads come down pointy end down.  I've always been skeptical, but I suspect that having the same aerodynamic characteristics going up simplifies things enough to reuse the envelope.

* I really don't think that the US military gave the artists who make the various animations more than they "needed to know".  That likely includes which way the warhead was facing coming down.  But "pointy end down" certainly makes any defense much harder, and lowers the potential for fratricide.

You're correct; the majority of nuclear warheads re-entered pointy-end-down. This was intentional. For one thing, ICBMs re-enter at much lower than orbital velocity, so they don't have nearly as much heating to deal with. But, more to the point, the purpose of a re-entry capsule is to slow down as rapidly as possible. An ICBM, on the other hand, doesn't need to slow down at all, so as long as it survives to impact, everyone is happy.

Well, everyone on the sending end. Not so much on the receiving end.

[DerekL1963]

9 hours ago, sevenperforce said:

You're correct; the majority of nuclear warheads re-entered pointy-end-down. This was intentional. For one thing, ICBMs re-enter at much lower than orbital velocity, so they don't have nearly as much heating to deal with. But, more to the point, the purpose of a re-entry capsule is to slow down as rapidly as possible. An ICBM, on the other hand, doesn't need to slow down at all, so as long as it survives to impact, everyone is happy.

Though there are other reasons I won't talk about, one of the key reasons an ICBM RV enters pointy-end-first is that retaining as much of it's speed as possible as low as possible makes it much harder to intercept.  They have more heating than you might think because they fly a very high arc, the information released after a recent test of a Trident-II indicated that it reached "more than twice the height of the ISS".

That being said, back to Gemini...  I suspect that since the area of the flat nose was such a small portion of the total that there was no particular reason to make it pointier, and since it was carried all the way to orbit they didn't want to make it heavier either.

[magnemoe]

24 minutes ago, DerekL1963 said:

Though there are other reasons I won't talk about, one of the key reasons an ICBM RV enters pointy-end-first is that retaining as much of it's speed as possible as low as possible makes it much harder to intercept.  They have more heating than you might think because they fly a very high arc, the information released after a recent test of a Trident-II indicated that it reached "more than twice the height of the ISS".

That being said, back to Gemini...  I suspect that since the area of the flat nose was such a small portion of the total that there was no particular reason to make it pointier, and since it was carried all the way to orbit they didn't want to make it heavier either.

Not only intercept but low drag and high speed trough the atmosphere also increase accuracy. 

And yest the flat nose is a bit weird, as its an cover over docking interface why not make it rounded?
I assumed it was because it had an LES but this was wrong. 

[Exploro]

For those interested here is a page that describes the abort modes for the Gemini.

[LegatusFlagrans]

Remember this was the Cold War, and the beginning of the space race; people were basically being strapped into tin cans on the top of ICBMs. They didn't really know what to expect with this sort of thing.

[radonek]

On 14. 4. 2017 at 4:27 PM, Kryten said:

Only a few early missile warheads used capsule-esque 'blunt body'

I don't think any warhead used that technique ever. Blunt-body capsule was invented for Mercury, when ICBM's were already well established. 

[MaxwellsDemon]

On 4/13/2017 at 0:27 PM, Nibb31 said:

I doubt they could have safely used the ejection seats with the Rogallo wing above them. But yes, it would have saved them in case of a parachute failure.

BTW, I just received my Gemini "Haynes Owners Workshop Manual" and it specifies that, in the event of ejection, the Rogallo would have been jettisoned first.

[Kryten]

36 minutes ago, radonek said:

I don't think any warhead used that technique ever. Blunt-body capsule was invented for Mercury, when ICBM's were already well established. 

http://afspacemuseum.org/displays/HeatsinkNoseCone/

[radonek]

@Kryten: I stand corrected. There is a whole chapter about it in This New Ocean.

[magnemoe]

10 hours ago, MaxwellsDemon said:

BTW, I just received my Gemini "Haynes Owners Workshop Manual" and it specifies that, in the event of ejection, the Rogallo would have been jettisoned first.

Like the Russian attack helicopter with ejection seats. the eject you first cut the rotor blades. I hope this system also eject the other crew member automatically afterwards  

[kerbiloid]

Though the rotor is already rotating, and its blades fly away themselves once being detached.
While the Rogallo wing is inert and heavy, and needs to be blown away.

[Nibb31]

18 hours ago, MaxwellsDemon said:

BTW, I just received my Gemini "Haynes Owners Workshop Manual" and it specifies that, in the event of ejection, the Rogallo would have been jettisoned first.

Sure, but the main reason for needing to eject would have been a failure to properly deploy the Rogallo, meaning that they could find themselves in any kind of tangled mess where cutting the cords to the wing would fail to get rid of the Rogallo or where the capsule could be in the wrong orientation for a proper ejection.

The Rogallo was a cool idea, but the weight and complexity for deployment, steering, and the associated landing skids were an engineering nightmare.

[kerbiloid]

How would Big Gemini 7..10 passengers evacuate? Crew cabin looks same.

[Rune]

My phone does weird things. Disregard! (And delete if appropiate).

Edited April 17, 2017 by Rune

[Capt. Hunt]

10 hours ago, kerbiloid said:

How would Big Gemini 7..10 passengers evacuate? Crew cabin looks same.

As I mentioned above, Big-G would have been fitted with a traditional LES tower, rather then ejection seats.