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

[Abstract_Kerman]

I don't see how that's better

[Ten Key]

Gemini had ejection seats instead of an escape tower. 

 

 

[Dman979]

Moved to Science and Spaceflight.

[Nibb31]

2 hours ago, Abstract223 said:

I don't see how that's better

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.

[sevenperforce]

Better than one of the Russian designs, which had no parachutes on the capsule at all and used the ejection seat as the standard capsule egress route following re-entry.

[Abstract_Kerman]

20 minutes ago, Nibb31 said:

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

I know what is in there but I'm talking about the nose cone that covers the radar and docking port why would it be flat

[sevenperforce]

8 minutes ago, Abstract223 said:

I know what is in there but I'm talking about the nose cone that covers the radar and docking port why would it be flat

To fit the docking adapter on the unmanned Agena docking target.

[Ten Key]

6 minutes ago, sevenperforce said:

Better than one of the Russian designs, which had no parachutes on the capsule at all and used the ejection seat as the standard capsule egress route following re-entry.

Vostok had a parachute for the capsule, but even with the chute it hit the ground hard enough to potentially injure the squishy human inside.  

The follow on, Voskhod, had a braking rocket on the parachute line to soften the landing. NASA mostly sidestepped this problem by bringing their capsules down in the water, but even then hard landings were a problem. If memory serves, Gemini 9 was swinging on its parachute and punched into the side of a wave hard enough to rupture one of the internal water tanks. There was enough of a leak that the crew had a brief moment where they thought the capsule was sinking. 

[sevenperforce]

Both the Agena and the Gemini capsule launched with a fairing to protect the docking ports.

7 minutes ago, Ten Key said:

Vostok had a parachute for the capsule, but even with the chute it hit the ground hard enough to potentially injure the squishy human inside.  

Oh, right. Good catch. There was definitely a parachute on Vostok; it just wasn't enough to keep the person alive so they would eject once the altitude was low enough.

There's been at least one time that the braking rockets on the Soyuz failed. I believe there were some spinal compression fractures but at least everyone lived.

[Ten Key]

1 hour ago, Abstract223 said:

I know what is in there but I'm talking about the nose cone that covers the radar and docking port why would it be flat

I think at some point the additional weight and complexity of a streamlined cover overwhelms any aerodynamic gains you might see from rounding that blunt nose off. 

It's worth noting that the Mercury escape tower also had a more or less flat nose.

[Brotoro]

Although in the case of the Mercury escape tower, that aerospike on the front is supposed to produce a conical shock that deflects oncoming air and reduces the drag of the escape tower.

(Not to be confused with an 'aerospike' rocket engine, which is a different beastie)

[Kryten]

2 hours ago, sevenperforce said:

Oh, right. Good catch. There was definitely a parachute on Vostok; it just wasn't enough to keep the person alive so they would eject once the altitude was low enough.

I'm pretty sure the flights with dogs didn't involve ejection, and they turned out fine. Most likely it would just be a very unpleasant landing like Soyuz 5, not a fatal one.

[mikegarrison]

18 minutes ago, Kryten said:

I'm pretty sure the flights with dogs didn't involve ejection, and they turned out fine. Most likely it would just be a very unpleasant landing like Soyuz 5, not a fatal one.

I thought the dogs didn't come back. Or was that just the early dogs? Guess I was wrong. Wikipedia says most of the dogs survived, and some even went into space more than once.

Edited April 13, 2017 by mikegarrison

[Ten Key]

14 minutes ago, mikegarrison said:

I thought the dogs didn't come back. Or was that just the early dogs?

The second Soviet satellite launch had a dog aboard and was non-recoverable. I think subsequent flights with dogs were test flights of the Vostok spacecraft (under the name Korabl-Sputnik) and were designed to be recovered. 

[p1t1o]

Atmospheric drag is not the biggest difficulty facing rockets going into orbit, after the first couple of hundred thousand feet vertical, aerodynamics dont matter any more, the mass of an aerodynamic cap (and the danger of colliding with it after jettison) probably outweigh the gains.

[sevenperforce]

1 hour ago, p1t1o said:

Atmospheric drag is not the biggest difficulty facing rockets going into orbit, after the first couple of hundred thousand feet vertical, aerodynamics dont matter any more, the mass of an aerodynamic cap (and the danger of colliding with it after jettison) probably outweigh the gains.

Apparently that's not what NASA thought when they built Gemini....

Gemini 5 nose cone shown.

[p1t1o]

@sevenperforce ah well there you go!

/thread

[kerbiloid]

This is an ICBM. They should be thankful for seats and parachutes.

P.S.
Gemini shape amazingly looks like a warhead.

Edited April 13, 2017 by kerbiloid

[Matuchkin]

17 hours ago, sevenperforce said:

Better than one of the Russian designs, which had no parachutes on the capsule at all and used the ejection seat as the standard capsule egress route following re-entry.

You mean like:

 

[MaxwellsDemon]

IIRC, the ejection seats on Gemini were "double-duty," both in case of a problem at launch and at landing-- the original concept had the capsule landing in a controlled glide under the 'Rogallo' wing/parachute.

[Nibb31]

2 hours ago, kerbiloid said:

This is an ICBM. They should be thankful for seats and parachutes.

P.S.
Gemini shape amazingly looks like a warhead.

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

[Ten Key]

I'm not sure that nose cap was there for aerodynamic reasons-- it looks more like a protective cover to me. 

It doesn't seem like there are many decent pictures of it. . .all of the pictures I can find of the Gemini spacecraft on the launch pad are from below, and that makes it hard to see the cap on top. This was the best I could do. . .

Quote

"The nose fairing is rigidly but temporarily fastened to the forward end of the R & R section. The fairing is Jettisoned at spacecraft separation from the launch vehicle. A pyrotechnic igniter severs a shear pin and swings the fairing clear of the spacecraft. The docking latch receptacles are exposed as the fairing is Jettisoned."

-- Source

 

 

 

 

It looks like the fairing is perfectly flat except for that small raised bit that accommodates the UHF antenna. It doesn't seem to significantly change the shape of the nose. 

[p1t1o]

5 minutes ago, Ten Key said:

It looks like the fairing is perfectly flat except for that small raised bit that accommodates the UHF antenna. It doesn't seem to significantly change the shape of the nose. 

Which raises the question - why bother putting a cap on and not making it aerodynamic? Unless aero resistance is like really insignificant.

[Nibb31]

1 hour ago, MaxwellsDemon said:

IIRC, the ejection seats on Gemini were "double-duty," both in case of a problem at launch and at landing-- the original concept had the capsule landing in a controlled glide under the 'Rogallo' wing/parachute.

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.

[MaxwellsDemon]

Ejection seats are rarely safe to use at any time.   They're primarily there because they're slightly better than the alternative...