TAKE OFF FWD
AFT Nose gear strength (high weights)
Main gear strength (high weights)Impossible rotation
Nose gear adherence Elevator maximum deflection +
Tail strike maneuverability margin
Neutral Point Maximum elevator deflection (max
1° per g point load factor)
IN FLIGHT FWD
AFT Elevator maximum deflection +
Neutral Point maneuverability margin
1° per g pointMaximum elevator deflection (max
THS stall limit load factor)
Go around Alpha floor protection
LANDING FWD
AFT Nose gear strength
Main gear strengthElevator maximum deflection +
Neutral Point maneuverability margin
1° per g pointMaximum elevator deflection (max
THS stall limit load factor)
Go around Alpha floor protection
WEIGHT AND
BALANCE
WEIGHT AND
BALANCE
A. GENERALITIES

4.7. Certified limits definition
4.7.1. Take off limits
a) Forward limit
The design of the forward limit takes into account the following:
. Nose gear strength
. Take-off rotation
. Maneuverability (efficiency of the elevator when aircraft in-flight)
. Flaps/slats extension (final approach in case of emergency landing). Those limitations are classified as handling quality and structural limitations
As seen previously (in —Influence of CG Position on Performance“), the FWD CG limit is the reference CG for aircraft performance, as it corresponds to the worst CG position, as far as performances are concerned.
.
From the performance point of view the forward limit of the envelope must stay as aft aspossible.
On the other hand, in order to facilitate the loading of the aircraft, the envelope must be as wide as possible (both aft and forward). If the envelope is too narrow, the operators will have to be very careful on where they locate the freight in the holds and on how they sit their passengers in the cabin.
.
 From the loading point of view the forward limit must not be too aft.
The retained limit is a compromise between loading and performance. In most of the cases, the handling qualities are ahead of the retained limit. In other words, the envelope could be widened without any impact on handling quality and aircraft safety. However, the handling quality of some —nose heavy“ aircraft are already rather limiting. It would penalize the loading to set a more aft limit and in this case, the forward limit corresponds to the handling qualities limitations.

A. GENERALITIES
b) Aft limit
The design of the aft limit takes into account the following:
. Main gear strength
. Nose gear adherence
. Take-off rotation (Tail strike)
. Stability in steady flight and during maneuvers
　
中國航空網 m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：Getting to Grips with Aircraft Weight and Balance(48)