Project HASDA - Reusable Crew Vehicle (lifting-body spaceplane)

[Pipcard]

I mean right before it touches the water.

According to this NASA page, the HL-20 (about 10000 kg) would've used three emergency parachutes, but I can't find any pictures to see exactly how it would look like, although the Astronautix page for HL-20 mentions a "tail-down water landing." Presumably it would float in the water horizontally in order for the egress hatches to be more accessible.

---------- Post added at 11:08 PM ---------- Previous post was at 11:44 AM ----------

The full mass (including docking adapter) of the lifting body will be 9390 kg, and the mass of the fuel itself is 1600 kg. This will provide about 575 m/s of delta-v with N₂O₄/MMH engines (316 s of specific impulse), allowing it to travel to destinations a couple hundred kilometers higher than the ISS.

N₂O₄/MMH is toxic, you say? SpaceX seems to be fine with it. Originally, they were going to be hybrid (rubber and laughing gas) rockets, but I switched because I've been reading about how the lower performance and stability issues outweigh its non-toxicity. Apparently it's a "losing technology" as well, according to therealdmt.

(note that SNC hasn't actually announced an abandonment of their hybrid engines yet at this time)

The volumes for the oxidizer and fuel tanks will be about the same if you use the Shuttle OME's oxidizer:fuel ratio (1.65:1) and take into account the density of both (1.450 and 0.880 g/cc, respectively)

oxidizer: 1.65 (mass)/1.450 (density) ≈ 1.138 (volume)
fuel: 1 (mass)/0.880 (density) ≈ 1.136 (volume)

 

[PhantomCruiser]

N₂O₄/MMH is toxic, you say?

Why yes, I do say. And it would seem that I'm not alone.

They are also not exactly the same thing... N₂O₄ (last I read) is being phased out of the Russian program, it's what killed Cyclone and Kosmos. And is one of the drivers for Angara. It's also what killed the American Titan (or at least one of the things).

MMH was used on the shuttles.

Doesn't matter who uses/used them, hypergolics are nasty.

 

[Pipcard]

So why doesn't SpaceX have a problem with using it on their manned Dragon V2?

 

[PhantomCruiser]

Because they work, are pretty simple and were used on the shuttle.

That still doesn't mean you want to be the first guy to run up and high five the crew once it's recovered on the pad. I mean, sure, that's what I'd want to do, but I'd have to wait until it's declared safe by some lab-coated guys.

From wikipedia "The corrosivity, toxicity, carcinogeneity of traditional hypergolics necessitates expensive safety precautions."

 

[Pipcard]

I already know they require "expensive safety precautions"

 

[PhantomCruiser]

Well OK then. I'm outta here.

 

[Pipcard]

Rudimentary docking adapter & main engines. The total mass of the craft is 9390 kg, but without the adapter it is only 8831 kg.

Each of the six engines (in clusters of three) has a maximum thrust of 103.9 kN (total of 623.4 kN), providing a built-in abort system with about 7 Gs of acceleration. A deep throttle capability also allows them to provide 10% 5% of the full thrust for orbital maneuvering operations.

(How does SpaceX's SuperDraco manage to have such a high thrust in such a small engine?)

 

[Donamy]

Wouldn't a water landing, necessitate a dorsal escape hatch ?

 

[Pipcard]

Yes, it will have a top hatch.

 

[Pipcard]

Made a dorsal hatch, completed the docking adapter, and made the engines smaller.

(At 83.1 kN each, they will provide about 5.8 Gs during abort. With 5% throttle, this will mean 0.29 G. With 2/3rds of the engines running, that's 0.193 G for orbital burns)

 

[Donamy]

Holy tight squeeze Batman.

 

[Pipcard]

The transfer tunnel has an internal diameter of 0.839 m, but the hatch is 0.6831 m so that it can rotate more freely.

 

[Urwumpe]

The transfer tunnel has an internal diameter of 0.839 m, but the hatch is 0.6831 m so that it can rotate more freely.

Don't you think that this is a tiny bit tight?

 

[Pipcard]

Well, it is probably tight for a person who is 24.2 in (61.468 cm) wide.

The tunnel is 0.839 cm because I wanted it to be a certain height from the bottom (where the heat shield is) and not interfere with the upper elevators. But maybe I can make it slightly bigger.

 

[Urwumpe]

Well, it is probably tight for a person who is 24.2 in (61.468 cm) wide.

Remember that you not only have to pass through as greased slim fit, but also work, move yourself and pass cargo through the tunnel. 90 cm might appear like a huge diameter to you, relative to your body, but when you have to move through a 90 cm diameter tube its a challenge.

 

[Pipcard]

There will be ladder rungs or something like that.

 

[Urwumpe]

There will be ladder rungs or something like that.

Where? And what do you expect there to make life easier? The smallest German standard manhole cover is 600 mm diameter, the most common one 800 mm ... 600 mm is VERY tight if you have to move in it, regardless of the ladder that is installed in it.

 

[Pipcard]

Where? Inside the tunnel, of course, so astronauts can climb "up" and "down"

Good thing it's larger than 600 mm, then? (I changed the hatch diameter to 739 mm with the tunnel being 900 mm)

 

[Urwumpe]

Where? Inside the tunnel, of course.

Good thing it's larger than 600 mm, then? (I changed the hatch diameter to 739 mm with the tunnel being 900 mm)

As said - it is very hard to pass through such a hatch.

 

[ISProgram]

Wait, so what's the diameter for a "typical" docking hatch, like APAS?