The largest plane ever built, but will it fly?

[bob10]

Building Stratolaunch, the Most Audacious Flying Machine Ever | WIRED (https://www.wired.com/story/stratolaunch-airplane-burt-rutan-paul-allen'mbid=nl_082018_daily_list1_p4&CNDID=52475003)

[Homestar]

That's quite large... 😁 Boasting a takeoff weight around the 600 tonne mark is staggering...

Will be interesting to see it fly. It doesn't look strong enough between the two hulls to support the loads that will be placed on it, but I'm sure the Engineers know what they are doing.

[JDNSW]

Rutan is a competent and experienced designer - I have no doubt it will fly. It suffers from one major issue - how many airfields can accommodate something that size?

[bob10]

The airfields that accommodate the space shuttle, I guess. After all, it is not a commuter aircraft.

[JDNSW]

The space shuttle could use quite a few airfields - especially in an emergency where pavement damage was acceptable. (This was discussed in a well researched novel "Shuttle Down", can't remember the author, quite a few years ago, which canvassed an emergency shuttle landing on Easter Island . There was no major issue landing it, but with the thing stuck on the runway, preventing anything else landing, and nothing on the island capable of towing it off, where do you go from there?)

The relevant issue here is probably width, including main gear track width. I don't expect its takeoff distance would be extreme, compared, for example to a 747 at MTOW, and it would normally land very light and hence short.

[rick130]

Rutan is a competent and experienced designer - I have no doubt it will fly. It suffers from one major issue - how many airfields can accommodate something that size?I remember talking to a bloke I knew many years ago who was an ex-RAF fighter pilot and test pilot.
He really didn't like Bert Rutan's early designs, the Vari-eze and Long-eze

[JDNSW]

Despite some misgivings about some of his designs, the company, Scaled Composites, has for decades been the goto company for special designs. Unless the requesting bill payer poked their nose into the design excessively, I have no doubt it will fly.

As an aside, people have been questioning "will it fly" every time an unusually large aircraft was built, from Sikorsky's "Le Grande" in 1914, to the Zeppelin Staarken of 1916, to the Dornier Do X, to the Maxim Gorki, to all the subsequent large aircraft.

And they have all flown, admittedly, some of them not very well!

[Hugh Jars]

The space shuttle weighs less than 80 tonnes. A bit more than a 737. It’s the wing and associated higher approach speeds that drive the landing distance up.

Most of the airports that take an A380 needed infrastructure works to be able to cover the wingspan when manoeuvring on the ramp, moreso than runway works to cover its weight.

The A380 can operate out of a 45m wide runway. Can this thing?

Doubt it.

[JDNSW]

So do I!

[cripesamighty]

So basically it can take off and land from only one place. That might be a bit limiting in an emergency, and since they have only built one, it might be catastrophic!

[Tins]

Fascinating, the parallels. Not many things got in Howard Hughes' way. Not a lot different here, really. Spruce Goose flew. Why not this? Love the adventure, unattached to the money.

143646

[Eevo]

if it doesnt fly, is it still a plane?

[Tins]

if it doesnt fly, is it still a plane?

Spruce Goose got off the ground, or at least the water..., so I'm not sure of your point...

[Eevo]

Spruce Goose got off the ground, or at least the water..., so I'm not sure of your point...

did you hear the joke about the rhetorical question?

[JDNSW]

I remember talking to a bloke I knew many years ago who was an ex-RAF fighter pilot and test pilot.
He really didn't like Bert Rutan's early designs, the Vari-eze and Long-eze

Thinking about that, I suspect that the reason for this is likely to be the bad taste left by the most celebrated previous home build canard design, the 'Pou de Ciel', which gained a reputation for killing owner-builders.

The problem with a canard design is that unlike a conventional design, it does not invariably inherently recover automatically from a stall.

In a conventional design, the tail plane pushes down rather than up, as does the main lifting wing, so that if speed drops to where the tailplane stalls, with the centre of gravity ahead of the mainplane centre of lift, the nose drops, so airspeed increases, and similarly, if the mainplane stalls first the, nose drops and airspeed increases, so that in both cases, control is regained.

With a canard design, since the canard is lifting normally, if it stalls, the nose drops. But if the mainplane stalls first, the nose lifts, and things can get very interesting. Canard designs always take great care to make sure that the canard always stalls first. The advantage of a canard design is that both wings are lifting, increasing efficiency - i.e. faster, everything else being equal.

(And the Pou de Ciel was not, strictly speaking a canard design, but rather had two equal wings, close coupled, with vertical control by tilting the front wing. Air tunnel tests on a full scale one showed that the issue was that the short distance between the two wings resulted in interference between airflow over the wings under landing conditions, which could result in loss of control. Later versions increased the wing spacing to (allegedly) correct the issue. But this gave all canard designs a bad reputation.)