I recently visited STT/TIST and by-extension EIS/TUPJ in the Virgin Islands, on back to back sailing trips. I flew a 757-200 from DL and a 737-800 from SY, although the later required a refuelling stop in SJU/TJSJ as the 737 either couldn't takeoff with full fuel from STT or needed slightly more fuel to fly against headwinds on the return flight. Watching a DL 757 touchdown hard and use what I surmised is full breaking to stop on the shorter runway at TIST from the vantage point of the ramp waiting to board via air-stairs, I got to wondering:

• IF Boeing were to take a section or two off of the already shorter 787-8, would that be enough to match the 757-200's MTOW at ISA of 6000'? Something Boeing could market to existing 757 Carriers for routes that cannot be 1:1 replaced with an A321LR or A321XR?

Not enough buyers for a small market where field performance is that critical. Sooner stop for fuel than buy a sub-fleet for just a few locations.

systo wrote:

I recently visited STT/TIST and by-extension EIS/TUPJ in the Virgin Islands, on back to back sailing trips. I flew a 757-200 from DL and a 737-800 from SY, although the later required a refuelling stop in SJU/TJSJ as the 737 either couldn't takeoff with full fuel from STT or needed slightly more fuel to fly against headwinds on the return flight. Watching a DL 757 touchdown hard and use what I surmised is full breaking to stop on the shorter runway at TIST from the vantage point of the ramp waiting to board via air-stairs, I got to wondering:

• IF Boeing were to take a section or two off of the already shorter 787-8, would that be enough to match the 757-200's MTOW at ISA of 6000'? Something Boeing could market to existing 757 Carriers for routes that cannot be 1:1 replaced with an A321LR or A321XR?

One thing to keep in mind when thinking of A320737 series versus 757 landing performance is that the 757 twice as many main landing gear brakes as the smaller narrowbodies. So even though it's landing weight my be higher, its stopping power is much greater (double?). The landing weight is nowhere near double. Also, at least on the 737 9 and I presume the 10, landing with full flaps increases deck angle and causes higher risk of tail strike. I assume the same risk for the 321. The 757 not so much, IIRC most 757 tail strikes are from takeoff.

My guess is that the 787 would have eye watering stopping capability at low landing weights due to its very high takeoff weight (accelerate stop requirements) capability.

The 787-10 does fine out of of OGG, which is 7000ft. United has run it on OGG-ORD in the past.

The takeoff performance of the 787 is already very, very impressive.

Would also be horrendously heavy for the payload. The 788 is already on the heavy side.

Shortening an airplane has no real effect on takeoff performance. All you are doing is removing a bit of airframe weight, but if that's the way you want to get better takeoff perf you might as well simply limit your takeoff weight.

In fact, shortening an airplane may end up increasing your Vmc and push the rest of your Vspeeds up, resulting in longer takeoff runs... unless you design a larger (and heavier) rudder.

Just get the -8/9 and limit your takeoff weight the few times you need the performance.

If Boeing was to offer an improved T/O perf package, it would mostly center on aerodynamic tweaks of the wing and high lift devices and some software upgrades. None of which would be likely to find any interest among customers.

As others have pointed out a shorter airplane does not necessarily improve takeoff performance as most of the weight reduction comes from the reduced payload rather than the minimal reduction in airframe weight, so on those few flights to/from performance-limited airports it would be better for the company to simply limit the payload rather than invest in a few special airplanes (with permanently-limited payloads) which would then be dedicated to those routes. Any airplane can take off or land on (almost) any runway if it's light enough. A shorter airplane may also require modifications to the vertical stabilizer and rudder in order to keep Vmc acceptable. The A318 is a good example of this; its tail is 30 inches taller than other A320 family airplanes and I would assume this translates into increased weight (although the A318 is lighter overall than the A319/20/21).

The one area where a shorter airplane is better, solely by virture of being shorter, is cruise performance. Subsonic airplanes are primarily limited by skin friction drag which is a function of speed and surface area (similar to the concept of "wetted surface" for boats), so an airplane with less surface area will generally burn less fuel in cruise. This is illustrated best by the 747SP which has a higher cruise speed and longer range than other 747 variants despite carrying slightly less fuel. The SP was, of course, designed and sold during a unique time for a unique market and didn't sell well (45 total produced).

In summary, a shorter 787 would probably (in practice) have better short-field performance than current variants but this improvement would be due to the reduced available payload (and therefore weight) of such a variant, not because of anything special about being shorter. As companies can simply reduce payload for those cases where increased performance is needed, there is likely not a market for such a variant.

Are there limitations on rotation angle for longer 787s?

N1120A wrote:

The takeoff performance of the 787 is already very, very impressive.

Exactly.

Here's a BA 787-8 carrying cargo (complications with which made us 45min late) and fully laden with pax, operating a nonstop transatlantic (MSY-LHR) off of an only 7000ft/2134m runway.

https://www.youtube.com/watch?v=kmxW9V0g-vY



They had a 10,200ft runway available, but when the wind's from the south (as it often is during evenings at that airport), they usually just choose the shorter runway, because the 788 going only TATL has no trouble getting out of there, even with considerable loads. Video above follows the direction of the red arrow, below.