Merged The New Largest Plane in the world

3point14 said:
That's what I mean. Launching that high is saving delta V budget by minimising gravity and atmospheric losses both of which increase the required budget.
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Atmosphere, yes. Gravity, not so much.

At 50,000 feet gravity is about 0.5% lower, so it's hardly a great improvement.
 
WhatRoughBeast said:
Atmosphere, yes. Gravity, not so much.

At 50,000 feet gravity is about 0.5% lower, so it's hardly a great improvement.
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The way I see it, it's 50,000 feet of climbing under that gravity that the rocket doesn't have to do anymore.

Of course, the plane has to make the climb instead, so I'm not sure where the savings are.
 
3point14 said:
Except you've saved all the fuel that you'd use to get to 50,000ft. Thanks to the tyranny of the rocket equation, I think that's likely to be significant.
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I think the economics of this plane depends on turn around time. If they could get it turned around in short order (1 or 2 weeks), that's a lot of launches in one year.
 
Spindrift said:
I think the economics of this plane depends on turn around time. If they could get it turned around in short order (1 or 2 weeks), that's a lot of launches in one year.
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My reading is that it seems, in terms of saved Delta V, it's not a lot more than 500Km/s, which isn't a great deal on a 10Km/x budget, so I think you might be right.

The other advantage is that the motor is going to be working, I would guess, in a more limited range of atmospheric pressures, so can be more efficiently designed.
 
theprestige said:
Of course, the plane has to make the climb instead, so I'm not sure where the savings are.
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Rocket fuels, which are either more expensive than jet fuel, or more difficult to store (or both), which increases engineering and operating costs.

The most notable savings is that the jet is an air-breather and doesn't need the oxidizer that the rocket needs, which typically tends to be liquid oxygen. Substantially reduced requirements for both fuel and oxidizer reduces both the fuel budget and engineering budget required for the rocket itself.

The type, and therefore cost, of the fuel also changes depending on whether the rocket is required to perform at atmospheric pressures (traditional first-stage boosters) or lower upper-atmosphere pressures (later stage boosters and orbital engines).
 
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Mike! said:
That's all well and good, but I'd still feel better about it if the tail section was interconnected too. But what do I know?
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Perhaps they were worried the interconnected tail could either collide with the rocket in carried flight, or that at launch, the rocket exhaust might put unacceptable aerodynamic loads on the interconnected tail, leading to unstable flight right at launch time?*

*I'm just an armchair enthusiast, so I've no idea, I'm just speculating.

3point14 said:
He's clearly used the autostrut feature.
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:D It also clearly needs MOAR BOOSTERS and they should most likely check their staging :p

Autostrut feels like a cheat :D
 
The plane also has the enormous benefit of that wing providing lift whereas a rocket provides none.

And as said above, the oxygen is taken from the air, not carried, saving a lot of weight too.
 
3point14 said:
My reading is that it seems, in terms of saved Delta V, it's not a lot more than 500Km/s, which isn't a great deal on a 10Km/x budget, so I think you might be right.
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Although...

(Is it bad form to quote oneself?)

It is the first 500Ms (Not Km/s as I totally mistyped above) Whish is a bucketload of fuel compared to the last 500Km/s


So it's going to need a less powerful engine designed for flight in a more limited range of pressure?
 
As has been said the An-225 is rather heavier, and actually works.
Also most of the old shuttle emergency runways max out at 3.2km.
 
3point14 said:
Although...





(Is it bad form to quote oneself?)





It is the first 500Ms (Not Km/s as I totally mistyped above) Whish is a bucketload of fuel compared to the last 500Km/s








So it's going to need a less powerful engine designed for flight in a more limited range of pressure?
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Yes, that sounds right. The engine doesn't have to be able to lift the rocket plus the extra fuel to reach another 500m/s, and doesn't have to be compromised in design to run efficiently in the lower atmosphere.
 
I was going to question the statement of 500,000 lb payload but it actually says that on StratoLaunch's website. Also max GTOW (Gross Takeoff Weight) of 1.2 to 1.3 million pounds.

From the pix, it looks like they've reused the windscreens from the donor 747's. Makes sense. The rudders also look like 747 hardware. I'm going to have to look for pictures, but the main landing gear looks like 747 body gear. If so, they've got three airplanes' worth there.

ETA: I'm dying to see a flight deck picture. I worked on 747 mechanical cockpit controls for 20+ years. Among other things.
 
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I wonder what is in the part of the plane that is above the wheels? Fuel? Do they really need it to be so big? If they could reduce the size of that then it would reduce the weight of the empty plane + less air resistance.
 
rjh01 said:
I wonder what is in the part of the plane that is above the wheels? Fuel? Do they really need it to be so big? If they could reduce the size of that then it would reduce the weight of the empty plane + less air resistance.
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Likely fuel and onboard equipment to monitor and manage the rocket ignition and deployment. I'm guessing the wheels are that big to distribute the weight properly. Also probably helps with clearance for the rocket.

If something goes wrong with the deployment, I would imagine that the plane needs to be able to land safely while still carrying the rocket loaded.
 
Octavo said:
If something goes wrong with the deployment, I would imagine that the plane needs to be able to land safely while still carrying the rocket loaded.
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If it can do that it would be a huge selling point for especially hard to replace payloads.
 
rjh01 said:
I wonder what is in the part of the plane that is above the wheels? Fuel? Do they really need it to be so big? If they could reduce the size of that then it would reduce the weight of the empty plane + less air resistance.
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Wouldn't it be hilarious if they made it twice as big as it needs to be by accident, because they're idiots?
 
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