Flight through thunderstorm outflows

Frost, W.; Crosby, B.; Camp, D. W.

doi:10.2514/3.44638

Cited by 15 publications

(4 citation statements)

References 2 publications

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“…The maximum radius occurs at the head-on and the minimum at the tail-on position, and the apparent displacement of the centre is: Note that in the case (b) of constant turn rate, the centre displacement [equation (41(b))] becomes equal to the radius 8 = r for a disturbance intensity equal to the weight G = 1-0, whereas in the case (a) of constant tangential velocity, a disturbance intensity G = TO would correspond [equation (41(a))] to an 'infinite' displacement, the downwind leg of the turn cannot be completed. Atmospheric disturbances affect not only turns but also other aircraft manoeuvres' 12 " 16 ', but it is beyond the scope of the present work to go into further details.…”

Section: (41(a))mentioning

confidence: 99%

“…It follows from equation (12(a)) that a combination of wind and shear equivalent to a tailwind of respectively 9% and 21% of the ground velocity, if not compensated, can cause an aircraft to stall respectively at unstick for take-off and on approach to land. To preserve safety margins, the stalling speed should be corrected for the presence of disturbances, according to equation (16) or Fig. 1.…”

Section: (17(a)(b))mentioning

confidence: 99%

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On aircraft flight performance in a perturbed atmosphere

Campos¹

1986

Aeronaut. j.

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SummaryWe consider the effect of atmospheric disturbances, such as wind, shears, turbulence, wakes and downflows, on aircraft performance (section 1), recalling the minimum of aerodynamics (section 2) necessary for the calculation of the effects on flight mechanics. For example, it is shown (section 3) that the relative lift change, due to wind, shear or both, coincides with the disturbance intensity G, defined as the instantaneous vertical acceleration, measured in g's, that an aircraft will experience as a consequence of atmospheric disturbances, assuming constant velocity and attitude. The disturbance intensity is a measure of the total force that the atmospheric disturbance can exert on the aircraft; this force may cause changes in normal acceleration, flight velocity and angle-of-attack, either isolated (section 5) or combined (section 6), in straight and level flight; in the case of a horizontal turn (section 7), the disturbance intensity specifies the changes in instantaneous turn rate, velocity, radius (section 8), acceleration and bank angle (section 9) due to atmospheric perturbations, and their cumulative effect over time in (section 10) deforming and displacing trajectories. These effects (section 11) are quantified by formulas and illustrated in graphics, and we indicate throughout the flight mechanical consequences of disturbances with the critical intensities G1 = — 0·17 and G2 = — 0·42; these are the disturbance intensities which, if uncompensated, would be just enough to cause an aircraft to stall (section 4) respectively at unstick on take-off and on approach to land. We conclude (section 12) with a discussion of the use of the disturbance intensity as a parameter in the reduction and analysis of flight data.

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Section: (41(a))mentioning

confidence: 99%

Section: (17(a)(b))mentioning

confidence: 99%

On aircraft flight performance in a perturbed atmosphere

Campos¹

1986

Aeronaut. j.

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“…. (2) (iii) the rotational inertia of the aircraft is neglected, so that the constant lift may be achieved through any combination of airspeed U and incidence 6 CL(6)17 2…”

Section: Effects Of Arbitrary Headwinds and Transverse Winds On The Amentioning

confidence: 99%

“…The effect of a given microburst, on aircraft flight, depends very much on the position of the flight path relative to the vortex centres, e.g., the intensity of the downflow and the abruptness of the change from head to tailwind will be greater if the aircraft flies directly through the vertical microburst axis and the effects of this on safe flight will be more severe if the axis lies only a short distance before the intended touchdown point because that point would be missed by a significant horizontal distance, or it would be reached at too high a sink rate, or both. While the simulation of known windshears has been proven generally accurate' 2,4 ', the main problem is their diversity, i.e. there are too many combinations of vortex position and intensity, flight path, touch down point, obstacle clearance, etc.…”

Section: Introductionmentioning

confidence: 99%

On a pitch control law for a constant glide slope through windshears

Campos¹

1989

Aeronaut. j.

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SummaryThe equations of motion of an aircraft flying at a constant glide slope (Fig. 3), in the presence of arbitrary head- or tailwinds, and up- or downflows is considered. The equations are integrated analytically, in the case of an aircraft initially on a steady flight, perturbed by winds of ‘moderate’ strength, in the sense that the wind velocity is not negligible compared to the aircraft's steady speed, but the ratio of their squares is much smaller than unity. The case of an approach through a downburst (Fig. 1), leads to winds which can be simplified to a one-period sinusoidal wind along the flight path, changing from head- to tailwind, at the peak of a superimposed downflow (Fig. 2), of half-period sinusoidal shape, and this is discussed in some detail. Data sheets are presented for three combinations of amplitudes of the head-to-tailwind and downflow; each contains plots of the scheduling of incidence that exactly cancels windshear effects, and of the groundspeed a'nd airspeed profiles which will keep the aircraft flying along the original glide slope. Each plot is given for a range of values of the windshear susceptibility parameter, representing aircraft with small or large inertia, with high or low approach speeds, including light aircraft, jet fighters and large transports; the cancellation of windshear effects isachievable only if the incidence schedule lies wholly below the stall limit. Since the rotational inertia of the aircraft is neglected, the short period mode is absent, and the pitch control acts to cancel the ‘phugoid’ instability induced on the aircraft by the wind profiles typical of a microburst.

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Effect of wind shear on flight safety

Hahn

1989

Progress in Aerospace Sciences

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Flight through thunderstorm outflows

Cited by 15 publications

References 2 publications

On aircraft flight performance in a perturbed atmosphere

On aircraft flight performance in a perturbed atmosphere

On a pitch control law for a constant glide slope through windshears

Effect of wind shear on flight safety

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