320 vs 321 MTOW

[Airmann]

Why can the A321 carry 16T more than the 320 given that they have the same wing? I'm sure there's a very logical and sound reason but I'd like to know what specifically allows for this increase in the T/O weight?

Looking at the 321 the big differences are:
1. Double Slotted Flaps
2. Length (different weight distribution)
3. Slightly more powerful engines

There's nothing else I can really think of. L/G?

I'm asking this because with the new sharklets Airbus is touting an increase of MTOW for 320 to 80T.

[toffeez]

I wouldn't say they are structurally the same wing. I do know that in pre-NEO days Airbus hesitated to add a 737-style winglet because the wing was on the strength limit.

[Cough]

I think the tyres are larger.

I believe the double slotted flaps give a greater wing area when retracted.

[Airmann]

Ok, so why not slap on the double slotted flaps and larger tires on the 320 and offer a HGW version?

[Cough]

Cost of certification vs sales?

[toffeez]

Airbus hesitated to add a 737-style winglet because the wing was on the strength limit.

[supercarb]

Larger wheels and brakes as well as tyres.

[toffeez]

The topic is Maximum Design Take-off Weight.

What have larger wheels, brakes, and tyres got to do with MDTOW?

[Kiskaloo]

toffeez
What have larger wheels, brakes, and tyres got to do with MDTOW?

Tire loading and RTO braking capability are both directly relevant to MDTOW.

[toffeez]

"Tire loading and RTO braking capability are both directly relevant to MDTOW."

???

[Spitoon]

???I've always wondered why the trucks I see on the road don't have the same tyres and brakes as my Ford Escort. Maybe toffeez can explain it to me. :rolleyes:

[Jonty]

Ok, so why not slap on the double slotted flaps and larger tires on the 320 and offer a HGW version?

They did, its called a 321.

The question I would pose is why would you want to? Where would you put the extra Fuel/Bags/Pax?

As for the differences between the 320 and 21. the landing gear is beefed up, the tyres are bigger the, engines are more powerful, and it has what airbus call a "high lift pack" for the wing. double slotted flaps in other words. Also, while the aero foil section of the wing is the same with the flap retracted, the internal structure is not. The 321 has no outer fuel tanks, for instance.

As for performance, it struggles. Although due to the higher wing loading it is more stable on approach, But your approach speeds are in the high 140kts, mid 150kts with flap 3.

[Max Angle]

I believe the double slotted flaps give a greater wing area when retracted.
Correct, 4 m2 more I seem to remember.

[keesje]

A320 - A321 is a big bump up in every respect.

The difference is 7 meters / 42 passengers.

http://www.valc.com.vn/images/home/a320.jpg

Boeing benefited the 737-800 and -900 are both in-between the A320 and A321 capacity wise.

IMO Airbus lacks a real 200 seater.

[Kiskaloo]

@toffeez
???

The Rejected Take-Off test is performed at MDTOW. For example, the A380-800 RTO was performed at a weight of 575 tons, even though the highest MTOW (WV002) at the time was 569t. Airbus has subsequently issued WV006 (573t) and WV008 (575t). If Airbus wishes to offer a higher MTOW than 575t, they will need to add the four additional main wheel braking units and perform a new RTO test.

Tire size and loading determines how much weight the undercarriage can support. Tire size and loading also affect pavement loading which determines how much weight an airport facility (runway, taxiway, ramp, bridge, gate, etc.) can support. When the 777-300ER first started operations at Paris-Orly, the pavement loading was so high that it damaged parts of the airport and additional structural reinforcement was necessary.

[Bula]

The A320 wing is over engineered. Originally it had the LAF function and outer wing tanks to reduce moment bending. After 20+ years of experience Airbus have realized the wing doesn't need these added features though I hear the LAF will be enabled again for the 78t MTOW version.