Dynamics and control of a Heavy Lift Airship in cross wind hover

Nagabhushan, B. L.; Tomlinson, N.

doi:10.2514/6.1981-1334

Cited by 1 publication

(1 citation statement)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where Equation (2) indicates that the open-loop vehicle is subject to pure convective motion. This results from the near-neutral buoyancy ratio condition (0.92) of the present vehicle.…”

Section: Vertical Acceleration Responsementioning

confidence: 99%

Effects of atmospheric turbulence on a quadrotor heavy lift airship

Tischler

Jex

1983

Journal of Aircraft

View full text Add to dashboard Cite

The response of a quadrotor heavy lift airship (HLA) to atmospheric turbulence is evaluated using a fourpoint input model. Results show interaction between gust inputs and the characteristic modes of the vehicle's response. Example loop closures demonstrate tradeoffs between response regulation and structural loads. Vehicle responses to a tuned discrete wavefront compare favorably with the linear results and illustrate characteristic HLA motion. <*z c w dB LPU L w _ s T h ,T' h w w r Nomenclature = acceleration of the hull center of gravity along,the positive (downward) z-body axis, ft/s 2 (g) = traveling upgust wave celerity, i.e., inertially referenced crest velocity, ft/s = decibels, = 20 log!o (gain) constraint force exerted on the hull support structure at the attachment point of LPU-1, along the positive (downward) z-bodyaxis, Ib = lift propulsion unit, each comprised of one rotor, one propeller, and one nacelle; numbering system shown in Fig. 2. characteristic scale length for vertical turbulence, ft ? hull length, ft = Laplace transform operator = heave mode time constants for the openloop (bare airframe) and closed-loop (control system engaged) vehicle, respectively, s (time-to-half-amplitude = 0.693 T\ T=Tf,,Tf l ) --reference relative airspeed, ft/s reference inertial velocity along the xbody axis (ground speed), ft/s = velocity of the hull center of gravity along the positive (downward) z-body axis, ft/s = heave axis control deflection, w c = 1 deg-vl deg of negative collective pitch on each rotor, deg = gust velocities along the inertial z axis at input sources 1-4, respectively; positive downward, ft/s Presented as Paper 82-1542 at the . Member AIAA. tPrincipal Research Engineer. Associate Fellow AIAA. a aa > d>* ww * ww Superscripts (")o = pitch and roll Euler angles, respectively, rad(deg) = root-mean-squared (rms) value = root-mean-squared(rms) level of hull acceleration, a z --root-mean-squared(rms) level of vertical constraint force at LPU-1 (F Czl ) = intensity level (rms) for turbulence along the inertial z axis, ft/s = power spectral desity function and truncated power spectral density function, respectively, for vertical turbulence, ft 2 /rad-s = frequency, rad/s = heave control system bandwidth; defined as the -3 dB frequency (Fig. 3), rad/s = Butterworth filter cutoff frequency, rad/s = pitch oscillation mode frequencies for the open-loop (bare air frame) and closedloop (control system engaged) vehicle, respectively, rad/s = traveling upgust wave encounter angle (Fig. 2), deg = average value = time derivative with respect to nonrotating axes

show abstract

“…where Equation (2) indicates that the open-loop vehicle is subject to pure convective motion. This results from the near-neutral buoyancy ratio condition (0.92) of the present vehicle.…”

Section: Vertical Acceleration Responsementioning

confidence: 99%

Effects of atmospheric turbulence on a quadrotor heavy lift airship

Tischler

Jex

1983

Journal of Aircraft

View full text Add to dashboard Cite

show abstract

Dynamics and control of a Heavy Lift Airship in cross wind hover

Cited by 1 publication

References 2 publications

Effects of atmospheric turbulence on a quadrotor heavy lift airship

Effects of atmospheric turbulence on a quadrotor heavy lift airship

Contact Info

Product

Resources

About