The Strength of the Pigeon's Wing Bones in Relation to Their Function

1967 ◽  
Vol 46 (2) ◽  
pp. 219-233 ◽  
Author(s):  
C. J. PENNYCUICK
Keyword(s):  
Shoulder Joint ◽  
Ultimate Load ◽  
Lift Coefficient ◽  
Load Factor ◽  
Forward Motion ◽  
Air Speed

1. Simple methods are described for applying known bending and twisting moments to pigeon bones. The ultimate bending and torsional strengths of the humerus and radio-ulna are determined. 2. Lift distributions are calculated from a strip diagram on the assumption that local lift coefficient is constant across the span. The position of the centre of lift is calculated for (a) gliding, in which the relative air speed is entirely due to the forward motion of the bird; and (b) hovering, in which it is entirely due to rotation of the wing about the shoulder joint. 3. Estimates of the ultimate load factor of the humerus in bending and twisting yielded 8.8 and 9.0 respectively in gliding, and 5.7 and 5.6 in hovering. Corresponding figures for the radio-ulna were 6.9 and 9.1 in gliding, and 4.0 and 5.1 in hovering. 4. The pectoralis insertion is strong enough to apply 4.2g in gliding and 2.9g in hovering, so the muscles would be forcibly extended before any danger could arise of the bones being broken by excessive lift. 5. A lift coefficient of at least 3.4 is achieved during the downstroke of hovering.

Aerodynamics of Gliding Flight in a Falcon and Other Birds

1970 ◽  
Vol 52 (2) ◽  
pp. 345-367 ◽  
Author(s):  
VANCE A. TUCKER ◽  
G. CHRISTIAN PARROTT
Keyword(s):  
Wind Tunnel ◽  
High Performance ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Wing Span ◽  
Technical Errors ◽  
Gliding Flight ◽  
Air Speed ◽  
D Values ◽  
D Value

1. A live laggar falcon (Falco jugger) glided in a wind tunnel at speeds between 6.6 and 15.9 m./sec. The bird had a maximum lift to drag ratio (L/D) of 10 at a speed of 12.5 m./sec. As the falcon increased its air speed at a given glide angle, it reduced its wing span, wing area and lift coefficient. 2. A model aircraft with about the same wingspan as the falcon had a maximum L/D value of 10. 3. Published measurements of the aerodynamic characteristics of gliding birds are summarized by presenting them in a diagram showing air speed, sinking speed and L/D values. Data for a high-performance sailplane are included. The soaring birds had maximum L/D values near 10, or about one quarter that of the sailplane. The birds glided more slowly than the sailplane and had about the same sinking speed. 4. The ‘equivalent parasite area’ method used by aircraft designers to estimate parasite drag was modified for use with gliding birds, and empirical data are presented to provide a means of predicting the gliding performance of a bird in the absence of wind-tunnel tests. 5. The birds in this study had conventional values for parasite drag. Technical errors seem responsible for published claims of unusually low parasite drag values in a vulture. 6. The falcon adjusted its wing span in flight to achieve nearly the maximum possible L/D value over its range of gliding speeds. 7. The maximum terminal speed of the falcon in a vertical dive is estimated to be 100 m./sec.

scholarly journals Ultimate Capacity of Vertical Pile Subjected to Combination of Vertical and Lateral Load

2019 ◽  
Vol 8 (9S2) ◽  
pp. 647-652
Keyword(s):  
Carrying Capacity ◽  
Ultimate Load ◽  
Lateral Load ◽  
Load Factor ◽  
Load Carrying Capacity ◽  
Vertical Load ◽  
Ultimate Capacity ◽  
Inclined Load ◽  
Load Carrying ◽  
Ultimate Load Carrying Capacity

Pile under general condition is subjected to combination of vertical and lateral loads In the analytical approaches to predict the load-displacement responses of a pile under central inclined load, it is assumed that the lateral displacement of the pile head is independent by the vertical load factor of the inclined load. Similarly, while estimating the ultimate resistance it is considered that the vertical load factor of the inclined load does not influence the ultimate lateral resistance of the pile during determination of ultimate load carrying capacity of vertical pile. In the present work, an empirical relation has been developed to predict the ultimate load carrying capacity of vertical piles subjected to combination of both vertical and lateral load in cohesion less soil. Effect of lateral load on vertical load deflection behavior of vertical piles when axial loads are present are discussed through several experimental results obtained from tests on model piles. Ultimate capacity is found to be a continuous function of ultimate lateral load, ultimate vertical load capacity and tangent of angle of resultant load made with vertical axis of pile.

Gliding Flight of the Andean Condor in Nature

1973 ◽  
Vol 58 (1) ◽  
pp. 225-237
Author(s):  
JERRY McGAHAN
Keyword(s):  
Drag Coefficient ◽  
Field Data ◽  
Lift Coefficient ◽  
Vertical Component ◽  
Induced Drag ◽  
Gliding Flight ◽  
Black Vulture ◽  
Air Speed ◽  
Andean Condor ◽  
Turkey Vultures

1. Derived in a vector analysis with measurements of wind velocity and ground velocity of the bird, the following mean air speeds were obtained for birds crossing a Peruvian beach: 15 m/sec for 15 gliding Andean condors, 14 m/sec for 42 condors that flapped during the crossing, and 10 m/sec for five turkey vultures that flapped. For the 15 gliding condors a mean lift coefficient of 0.7 and a mean induced drag force of 3 N were computed. 2. Implausibly low values derived for parasite drag coefficient of the condor appeared to be due to (a) unmeasured forces of deceleration and (b) an undetected vertical component of the wind at the level of the flight path. Field data, adjusted by introducing a coefficient of parasite drag determined for the black vulture in a windtunnel study provided corrected estimates of drag. I secured an adjusted value of 14 for the L/D ratio of a condor gliding with wings fully extended. 3. A moderate flexion of the wings reducing the span by 20% is estimated to increase the optimum air speed from 13.9 to 15.2 m/sec for an adult male condor and from 12.6 to 13.8 m/sec for an adult female.

Expected Value of Ultimate Load Factor

1973 ◽  
Vol 99 (2) ◽  
pp. 291-294
Author(s):  
Alberto Castellani
Keyword(s):  
Ultimate Load ◽  
Expected Value ◽  
Load Factor

AERODYNAMICS OF GLIDING FLIGHT IN A HARRIS' HAWK, PARABUTEO UNICINCTUS

1990 ◽  
Vol 149 (1) ◽  
pp. 469-489 ◽  
Author(s):  
VANCE A. TUCKER ◽  
CARLTON HEINE
Keyword(s):  
Wind Tunnel ◽  
Lift Coefficient ◽  
Drag Coefficients ◽  
Polar Curve ◽  
Wing Span ◽  
Gliding Flight ◽  
Black Vulture ◽  
Polar Area ◽  
Air Speed ◽  
Parabuteo Unicinctus

1. A Harris' hawk with a mass of 0.702 kg and a maximum wing span of 1.02 m glided freely in a wind tunnel at air speeds between 6.1 and 16.2ms−1. The glide angle varied from 8.5% at the slowest speed to a minimum of 5% at speeds between 8.0 and 14.7 ms−1. The maximum ratio of lift to drag was 10.9 and the minimum sinking speed was 0.81ms−1 2. Wing span decreased when either air speed or glide angle increased. Wing area was a parabolic function of wing span 3. Lift and profile drag coefficients of the wings fell in a polar area similar to that for a laggar falcon (Falco jugger) and a black vulture (Coragyps atratus). A single polar curve relating lift coefficients to minimum profile drag coefficients can predict the maximum gliding performance of all three birds when used with a mathematical model for gliding flight 4. The parasite drag values that have been used with the model are probably too high. Thus, the profile drag coefficients determined from the polar curve mentioned above are too low, and the predicted wing spans for gliding at maximum performance are too large. The predicted curve for maximum gliding performance is relatively unaffected 5. The maximum lift coefficient for the Harris' hawk in the wind tunnel was 1.6. This value is probably less than the maximum attainable, since the hawk's wings never appeared to stall. The best estimate of the minimum profile drag coefficient is 0.026 at a lift coefficient of 0.60.

Tests on a one-twelfth scale model of the Mancunian Way

1965 ◽  
Vol 1 (1) ◽  
pp. 57-68 ◽  
Author(s):  
G Somerville
Keyword(s):  
Ultimate Load ◽  
Bending Moment ◽  
Elastic Theory ◽  
Scale Model ◽  
Load Factor ◽  
Box Section ◽  
Effective Flange Width

A description is given of the building and testing of a 1:12 scale model, made of micro-concrete, of a typical interior span of the proposed Mancunian Way. Data have been obtained regarding the diffusion of prestress through the section, the behaviour of the structure under its design loading and under the action of point loads on the cantilevers, and the behaviour of the structure at ultimate load. It was found that the effective flange width to be used in calculating section properties varied along the span; the properties pertaining to the box section alone should be used at the support sections and those for the full section used at midspan. The behaviour of the structure under its design loading was satisfactory and could be predicted using simple elastic theory. The distribution of bending moment along the root of a cantilever, subjected to point loads, could best be predicted using the method due to Westergaard (1). At ultimate load, the structure was found to have a load factor of at least 3 on full live loading.

scholarly journals Conceptual design of Blended Wing Body for Future Air Transportation

2022 ◽  
pp. 133-139
Author(s):  
Shruti Dipak Jadhav ◽  
Pawan Hiteshbhai Jethwa ◽  
Shiva Prasad U ◽  
Suresh Kumar M
Keyword(s):  
High Speed ◽  
Lift Coefficient ◽  
High Volume ◽  
Local Area ◽  
Environmental Benefits ◽  
Surface Element ◽  
Aerodynamic Heating ◽  
Load Factor ◽  
Blended Wing Body ◽  
Bypass Ratio

Blended wing body is a fixed wing aircraft which are smoothly blended together with no clear dividing line and no distinct wings also be given a wide Aerofoil shaped body. The future transportation is of aircrafts will incline towards the aerodynamically efficient and capable of carrying large number of passengers over long range and environmental benefits is the main paradigm in the design of aircraft BWB has a high lift to drag ratio which increases the CL max and velocity of the airplane with high load factor and high economy compared with traditional aircraft. Evacuation pressure or the cabin pressurization is the major issues in most of the designs with the minimum aerodynamic lift coefficient and drag coefficient. On the other side of the trend is towards the increasing cruise speed. High speed flow is connected with overcoming of intensive drag rise accruing due to existence of intensive shock, closing local area of supersonic flow. Increase of flight Mach number is possible only by using flow control methods and through affecting the shock increases of aspect ratio leads to increase of lift coefficient corresponding to maximal lift to drag. High bypass ratio engines have smaller fuel consumption and lower noise level but have negative effect on flow around airframe including take-off and landing phases. The necessity of solving problem of intensive aerodynamic heating of surface element of flight vehicles and by ensuring of their stability and controllability and also by need of implementing of high-volume tanks for hydrogen fuel and super high bypass ratio engines.

scholarly journals Ultimate Limit State Analysis of Ship Structures

2019 ◽  
Author(s):  
S Sathish Kumar
Keyword(s):  
Ultimate Load ◽  
Progressive Collapse ◽  
Limit State ◽  
Structural Response ◽  
Load Factor ◽  
Ultimate Limit State ◽  
Ship Structures ◽  
Limit State Analysis ◽  
Ultimate Limit ◽  
State Analysis

Subjective and objective uncertainties are imposed on ship structures due to the random nature of the loading environment, inadequate knowledge of physical phenomena associated with loads or deviations in material properties which make reliable predictions of structural response a difficult task. Strength criteria for ships can be established by ultimate strength studies of progressive collapse analysis of finite element models under different boundary conditions with combined geometric and material nonlinearities. Load-Displacement and/or Moment-Curvature curves can be generated and the ultimate load causing failure identified as a multiple of the design load. Ultimate limit state analysis can be carried out for various combinations of parameters to identify the ultimate load factor in each case.

scholarly journals A deep learning-based procedure for estimation of ultimate load carrying of steel trusses using advanced analysis

2019 ◽  
Vol 13 (3) ◽  
pp. 113-123 ◽  
Author(s):  
Truong Viet Hung ◽  
Vu Quang Viet ◽  
Dinh Van Thuat
Keyword(s):  
Machine Learning ◽  
Neural Networks ◽  
Deep Learning ◽  
Test Data ◽  
Ultimate Load ◽  
Load Factor ◽  
Activation Functions ◽  
Steel Truss ◽  
Advanced Analysis ◽  
Steel Trusses

In the present study, Deep Learning (DL) algorithm or Deep Neural Networks (DNN), one of the most powerful techniques in Machine Learning (ML), is employed for estimation of ultimate load factor of nonlinear inelastic steel truss. Datasets consisting of training and test data are created based on advanced analysis. In datasets, input data are the member cross-sections of the truss members and output data is the ultimate load factor of the whole structure. An example of a planar 39-bar steel truss is studied to demonstrate the efficiency and accuracy of the DL method. Five optimizers such as Adadelta, Adam, Nadam, RMSprop and SGD and five activation functions such as ELU, LeakyReLU, Sigmoid, Softplus, and Tanh are considered. Based on analysis results, it is proven that DL algorithm shows very high accuracy in the regression of the ultimate load factor of the planar 39-bar nonlinear inelastic steel truss. The number of layers can be selected with a small value such as 1, 2 or 3 layers and the number of neurons in each layer can be chosen in the range [Ni, 3Ni] with Ni is the number of input variables of the model. The activation functions ELU and LeakyReLU have better convergence speed of the training process compared to Sigmoid, Softplus and Tanh. The optimizer Adam works well with all activation functions considered and produces better MSE values regarding both training and test data. Keywords: deep learning; artificial neural networks; nonlinear inelastic analysis; steel truss; machine learning.

scholarly journals The Profile Drag of a Hawk'S Wing, Measured by Wake Sampling in a Wind Tunnel

1992 ◽  
Vol 165 (1) ◽  
pp. 1-19 ◽  
Author(s):  
C. J. PENNYCUICK ◽  
CARLTON E. HEINE ◽  
SEAN J. KIRKPATRICK ◽  
MARK R. FULLER
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Dynamic Pressure ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Wing Profile ◽  
The Mean ◽  
Air Speed ◽  
University Of Bristol

The distribution of dynamic pressure behind a Harris' hawk's wing was sampled using a wake rake consisting of 15 pitot tubes and one static tube. The hawk was holding on to a perch, but at an air speed and gliding angle at which it was capable of gliding. The perch was instrumented, so that the lift developed by the wing was known and the lift coefficient could be calculated. The mean of 92 estimates of profile drag coefficient was 0.0207, with standard deviation 0.0079. Lift coefficients ranged from 0.51 to 1.08. Reynolds numbers were nearly all in the range 143000–194000. The estimates of profile drag coefficient were reconcilable with previous estimates of the wing profile drag of the same bird, obtained by the subtractive method, and also with values predicted by the ‘Airfoil-ii’ program for designing aerofoils, based on a digitized wing profile from the ulnar region of the wing. The thickness of the wake suggested that the boundary layer was mostly or fully turbulent in most observations and separated in some, possibly as an active means of creating drag for control purposes. It appears that the bird could momentarily either increase or decrease the profile drag of specific parts of the wing, by active changes of shape, and it appeared to use the carpo-metacarpal region especially for such control movements. Further investigation in a low turbulence wind tunnel would help to resolve doubts about the possible influence of airstream turbulence on the behaviour of the boundary layer. Note: Present address: Department of Zoology, University of Bristol, Woodland Road, Bristol BS8 1UG, England.

Sign in / Sign up

Export Citation Format

Share Document