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55 minutes ago, mikegarrison said:

Since I was tossing the term around -- "balanced field length" refers to the length required to reach takeoff speed, then reject the takeoff and come to a full stop again before running out of concrete.

I'd have to wonder if this would lead to the use of parachutes.  Not  so much to rescue the passengers during a disaster (although it might be sold as such), but to act similar to the parachutes used by drag racers to extend the runway and hopefully use a smaller airport.

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3 minutes ago, wumpus said:

I'd have to wonder if this would lead to the use of parachutes.  Not  so much to rescue the passengers during a disaster (although it might be sold as such), but to act similar to the parachutes used by drag racers to extend the runway and hopefully use a smaller airport.

Drag (drogue) chutes have certainly been used, particularly on military airplanes.

 

Typhoon_deploying_parachute_arp.jpg

Edited by mikegarrison
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1 hour ago, mikegarrison said:

By going fast. (And probably by having some high lift flaps and or slats you don't see in the picture.)

I will also note that last year Aerion started showing a different render:

Aerion_AS2_2020_design.jpg

One of the problems with the F-104 was its high landing speed, required because of its high wing loading.

According to Wikipedia, Aerion is aiming for a balanced field length of 7500 feet. That's pretty long for a business jet. Many business jets try for shorter field lengths so that their operators can fly into smaller airports.

That render looks like something that can fly.  The image in the article I linked looked like something that can only fall with style 

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The layout bears some semblance to the final proposed design of the (cancelled) Boeings 2707 SST from the 1960s. 

The initial version had variable sweep wings too - which would’ve been great for field performance. Its a shame variable geometry fell out of vogue - it really made for some good looking airplanes.

640px-Boeing_2707-300_3-view.svg.png

boeing_2707_sst-84885.jpg

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5 hours ago, mrfox said:

Its a shame variable geometry fell out of vogue - it really made for some good looking airplanes.

Was that because Fly-by-Wire took over predominance?  I love planes like the F-14, and its performance was legendary.  B-1B is certainly a performer... why did it's frame not get converted to a passenger version?

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57 minutes ago, JoeSchmuckatelli said:

Was that because Fly-by-Wire took over predominance?  I love planes like the F-14, and its performance was legendary.  B-1B is certainly a performer... why did it's frame not get converted to a passenger version?

Only really needed for large supersonic jets who few new has been build as in any after the B1?
Fighter jets probably has enough TWR to not need them. 
You also has the option to take off with less fuel and top up in the air. 

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 I think it’s a combination of better aero fluid modelling during the design phase, coupled with digital fly-by-wire that allows for more complex permutations of control surface positioning in flight. In a nutshell - computers.

There are some pretty big downsides to swing wings too... weight and mechanical complexity being the major one. Another is poor distribution of the center of pressure of the wing, resulting in high trim drag during supersonic flight.

A similar thing has happened in recent years that has seen the demise of triple and double slotted flaps and the elimination of active CG control - both replaced by better designed and actively positioned flaps brought about by better computers.

D-P9_T_XsAEXWdQ.jpg

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ADHF_A350.jpg
 

 

Another variation on the variable geometry theme  is the XB70, another elegant design with downward folding wingtips that better optimised wing area, longitudinal trim, increased vertical tail area for lateral stability and provided compression lift for Mach 3 cruise.

94eb47a45699ada5faea10a70c0ba4c1.png

Edited by mrfox
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Swing wings turned out to be not really worth the weight and cost.

43 minutes ago, mrfox said:

A similar thing has happened in recent years that has seen the demise of triple and double slotted flaps and the elimination of active CG control - both replaced by better designed and actively positioned flaps brought about by better computers.

This is mainly for noise reasons. The more slots in the flaps, the more aero noise during landing.

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46 minutes ago, mrfox said:

 

Careful, you are comparing an A320 to an A321.  You can tell by the cargo door position and over wing exit. The 321 is the only one of the family to have double slotted flaps whether CEO or NEO and has to do with it using 320 wings on a plane that is much heavier than a 320.

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On 1/14/2021 at 3:06 PM, Meecrob said:

Careful, you are comparing an A320 to an A321.  You can tell by the cargo door position and over wing exit. The 321 is the only one of the family to have double slotted flaps whether CEO or NEO and has to do with it using 320 wings on a plane that is much heavier than a 320.

Good catch with the picture and a poor misleading example on my part. you are correct on the 321 ceo and the initial 321 neo. It is on the latest 321 neo XLR that had the flap design change.

a321xlr-comparison-image_78147.jpg
 

Same thing for the 747 for its -8 update - triple slotted to double and single slotted.

a30459bc6de50ee7d6fede96d20d4cd0.jpg
710x528_13124627_8186117_1607409438.jpg
maxresdefault.jpg

Edited by mrfox
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