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I'm deeply interested in aerodynamics and CFD. I'm currently thinking about two masters:
_ one in aerospace dynamics which talk about flight mechanics, aerodynamics (lift, drag, flows characteristics ...) with modules about CFD, experimental aerodynamics (wind tunnel tests, measurements principles ).
_ CFD master which essentially talks about fluid mechanics, heat transfer, numerical methods, CAD, data analysis.
I want to become an aerodynamicist. I feel like the CFD master can give me a deeper understanding of fluid mechanics and more choices (I can work in fields like automotive, naval, aerospace). I'm more interested in aeronautics than other vehicles but it wouldn't bother to work for automobile or naval company. In the other hand the aerospace dynamics master is more centered on air-vehicles, can give me a good undertanding of flight dynamics and experimental skills not just numerical ones.
As I'm not experimented enough, I'm humbly asking which one do you think is the best for an aerodynamicist ?
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Hi, I am an engineering doctor (expected) at the Institute of Mechanics, CAS and I major in Fluid Mechanics. I am currently engaged in Hypersonic aerodynamics, Compressible flows, and Complex aerodynamic interference associated with shock waves in multi-body dynamic separation at high speed, CFD simulation, and wind tunnel tests. As my experience, the CFDers' work is more concentrating on better CFD methods, higher accuracy, faster calculating speed, and more reliable simulation results for complex and possible fluid flow in engineering problems. However, the aerodynamicist's work is to solve one of the specific or simply aerospace engineering problems, to study the flow mechanism associated with the considered problem, using the fluid mechanic's theory, CFD tools or numerical analysis, sometimes, the wind tunnel tests. Nevertheless, the fundamental knowledge of CFD, fluid mechanics, data analysis, etc., are essential for us to become qualified aerodynamicists. Whichever master or doctor to be, we are not just limited in it. The skills and expertise in aerospace engineering or aerodynamics are overlapping, cross and interdependence. When we choose to become a master, unknown things are approaching on the way. So, we would not be afraid of the thing we are not good at, we have the learning skills, and we can overcome something. By the way, the wind tunnel experiment is interesting, at least for me, and the experimental results are precious. Maybe, we could be more comprehensive by engaging in aerodynamics or aerospace engineering. Each master has its advantages and characteristics. Believe us, we can make something, and we can enjoy it. Just a little experience and feeling, hope that can help you.
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I am in the preliminary design phase of a heavy-lift octocopter. Is there a systematic approach to selecting the proper propeller, motor, and battery for the given configuration provided that the frame size is still variable, the required payload weight is W and the endurance is T minutes?
All of the above parameters are coupled so I am guessing this will be an interactive solution. Any suggestions?
Thank you in advance for your advice and guidance,
Filippos
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1) What exactly is the definition of a control law and what is the difference between control laws and controllers in the context of aerospace vehicles ?
2) Is the use of the term flight control law specific only to aircraft (fixed wing & rotorcraft) and UAVs, for in my experience the term is not actively used in the context of Launch Vehicles or spacecraft ?
(examples of FCLAW's: images 1 and 2) [1]
A few questions regarding the control laws of combat aircraft -
3) The Eurofighter(EF 2000) seems to use an interesting control structure - the Differential PI Algorithm, which is also a controller that is being actively used by the naval version of the Indian LCA. My question is, as the controller seems to be quite advantageous, why has'nt the Differential PI structure been used in other flight controllers ? [2](refer to image 3)
4) The testing of combat flight control laws has made use of test aircraft for in-flight simulation, for example the use of the F-16 VISTA (now X-62 VISTA) to test flight control laws of the Indian LCA. How does this work ? How is useful information to validate & certify the control laws of one aircraft obtained from the flight performance and input responses using these same control laws but on another aircraft ? (refer: VISTA.pdf)
Note: This is not exclusive to aircraft as such, the control laws for the SLS have also been tested on an F/A 18 Hornet.[3]
References:
[1] Balas, Gary J.,"Flight Control Law Design - An industyr perspective", European Journal of Control, Vol. 9, Issues 2–3, 2003,
[2] Osterhuber, R., et.al."Realization of the Eurofighter 2000 Primary Lateral/Directional Flight Control Laws with Differential PI Algorithm", AIAA GNC Conference and Exhibit 16 - 19 August 2004, Providence, Rhode Island
[3] "Flight Testing of the Space Launch System (SLS) Adaptive Augmenting Control (AAC) Algorithm on an F/A-18", NASA/TM-2014-218528
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1) Control laws (or controllers) can be applied to any plant (aircraft, vehicle, spacecraft, missile, etc.).
2) The term of flight control law applies to all air vehicles.
3) The flight control law design concept is diverse. Each control concept has advantages and disadvantages. While the differential PI control you asked about has some advantages, it has the disadvantage of being susceptible to noise due to differential effects. And while the NDI (Nonlinear Dynamic Inversion) control applied to the F-35 is sensitive to model uncertainty, if the model is accurate, it has the advantage that it can be commonly applied to A, B, and C versions with one control structure. This is because only OBM (On-Board Model) needs to be replaced. In addition, sensor-based INDI (Incremental NDI) is a method that is quite robust to model uncertainty, but it is difficult to obtain the measured angular acceleration, and the use of a filter that minimizes noise is essential when the angular velocity is differentiated from the IMU sensor. is. And although it has the characteristic of reducing the stability margin of the system (especially the phase margin), the stability margin is quite robust against uncertainty. Hybrid INDI, which takes advantage of these two control methods, is sometimes used.
4) IFS (In Flight Simulator) is a method that can be safely verified with an aircraft platform that has already been tested when developing a flight control computer or a new flight control rule. In other words, new functions can be efficiently verified while ensuring flight safety by using the already verified flight control system for take-off and landing and verifying the function with the newly developed flight control rule in a specific flight condition.
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I am study aircraft fly in the air,simulating body and rudder roll in 3D . I need dynamic mesh.As presented in ppt,the rudder rotate in the face perpendicular to the face body rotating.Now,I don't konw how to make udf for the dynamic mesh.Please help.
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Dear Neil,
Could you simulate this problem?. Actually I am trying to simulated same type of problem in which due to rudder 's deflection some additional forces act on aircraft and aircraft with rotate or turn with moving constant speed so direction of aircraft 's velocity change. Here my questions are - How did you combine the effect of 6 DOF on aircraft's moving direction? Did you write 2 UDFs separately for CG Motion & 6 DOF or in one UDF that is 6 DOF UDF you combined the effect of aircraft rotation due to 6 DOF?
Can you please help me in this. If possible, Please share your UDF with me. My all doubts will be clear by your UDF.
Thanks for your help.
Regards,
Bhupendra
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I want to model lazy eight maneuver by matlab simulink or AI.
what shall I do???
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The ability to track aircraft in flight has often been overlooked due to the cost implications but how possible is it?
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We have developed EFIS/GNSS aircraft satellite tracking system that can satisfy ICAO GADSS . http://www.sciencepubco.com/index.php/ijet/article/view/21320 .
We (UPNM/Worldgate) through university industry collaboration shall try to certify it as TSO so that it can be fitted to civil aircraft. .The sensors consist of 9 axis (accelorometers /gro/magnetometers) and GNSS(3D) that are telemetry to servers via iridium/gsm and short range IT devices via WiFi. Its not only provide tracking capability but also EFIS data except we don't install air speed since we want to be independent of aircraft system.
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It is my impression that an increasing number of airline passengers place cabin-sized suitcases in the overhead lockers.
1. Does anyone know whether there is an increased number of accidents from suitcases falling down when opening the overhead lockers?
2. Does it make a big difference for the pilots to fly the planes if most luggage is stored in the overhead lockers instead of the storage room? There are usually regulations in terms of number of items, size and weight of luggage declared as hand luggage, but what if these are not always adhered to?
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Typically the fuselage is centred around the Centre of gravity of the aircraft. Baggage can be underneath the floor, or in others (smaller) at the tail- or in the case of ATRs at the front. Airlines do check size and weigh of carry ons. and its obvious when bags are being lifted into the OH bins if they are heavy.. And the flight attendants do intervene. Once upon a time, we were testing a smallish airliner and two of us ran with a loaded in flight catering cart up and down the aisle to see how we could disturb the AC... This was say 500 pounds moving from one extreme to the other.. and the AC just sat there.. If every carry on bag was from a coin collector and they all sat at the front, (or rear) then there might be a Centre of gravity problem, but generally the distribution is symmetrical around CG and most airliners have a pretty wide CG range anyway- say 5% to 35% of MAC. The limits being stability at aft CG,, and ability to rotate at fwd CG... Could go on for hours on this if you wish
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Hello everyone!
Please I need a reference that could be used to build an aeroelastic model for an aircraft. The model should be simple, but yet accurate. It might be consisted of a simple aerodynamic model (lifting line, lifting surface, etc.) and a simple structural model (beam theory, etc.). The reference should give complete details and hands-on on how to build the model (not only theoretical derivations). The model should be fully implementable on MATLAB. It also needs to be finally represented in a state-space model that accounts for the ordinary rigid-body states, in addition to the flexible degrees of freedom. The results of the analytical model will be validated with real flight test data.
The aircraft to be modeled is a single-seated sailplane that has a wing span of 18 m, wing chord of 0.7 m, wing area of 11 m^2 and mass of 450 kg. The wing has low sweep and twist angles, and also a low tapering ratio with a considerable dihedral angle. The aircraft is constructed of composite materials (carbon fiber) and has a T-tail and ordinary control surfaces (aileron, elevator and rudder). The flight envelope is mainly characterized by altitudes up to 3 km and speeds from 100 to 160 km/h TAS.
The possibility of a mutual cooperation that will result in a published paper is also welcomed.
Thank you!
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Hi, I am not a specialist of this area but I have a colleague working in AIRBUS Toulouse that certainly can give you some elements. You can contact me directly and I will give you the email of this engineer.
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Towards solving Auto landing  problem of a UAV what maneuvers carried out for heading correction along the runway by the autopilot. what are the path planning  strategies.
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two fundamental points here. One is to get the device tracking along the landing area, that could be by ILS but mos UAV operations dont happen on major civil airpors which are he only ones with ILS. SO you should use a sequence of waypoints, both lateral and vertical to guide the UAV along the lateral and vertcial landing paths . BU second point is just as important. In any crosswind you need o be able to Kick off drift so you dont strain the landing gear. Wing down only works provided the UAV can deliberately "sideslip" AND  the cross wind velocity component is limited by the into wind wingtip clearance- for most UAVs, So the crabbing technique should be used. This works for all wind strengths, but requires this Kick off drift manoeuvre to be performed just before touchdown- To late and you may smack off your gear To early and the wind will start to drift the UAV off the centreline. email me- I m a flying instructor   
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For example, at what speed can the upper wing, fuselage cabin  of an airplane be formed ? 
I need to get an idea about speed scales ... 
Thank you in advance. 
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Can u elaborate 
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I want to design a missile with tails while controlled with canard fins. The question is how to make the missile of critical damping in its pitch-mode response to the elevator (actuator-fin) deflection? I mean I want to meet a critically damped response of pitch-angle dynamics to canard-fin deflections (actuation). Although the missile is spinning but if you answer about spin-stabilized missile, your answer is also welcomed. I do not want any oscillatory motion in pitch-mode (only pure damping is sought). You can imagine rolling-airframe missile RIM116 as my design goal and reply with regard to that. 
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You are right. But the main issue I'm concerned about is the spinning or rolling motion and how it interferes in longitudinal stability. Could we generalize conventional topics and talk about damping with proper position of fin if the missile has also a spinning motion? The missile is not spin stabilized. Thank you Manigandan.
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Recently, I have read some references applying proper orthogonal decomposition to solve unsteady aerodynamic problems. I'm very interested in this topic and really want to learn more about it. For now, I'm not sure how this method works, so, can anyone who is familiar with this topic give me some advice about starting in this field? Or some recommendations for related materials (books and references that may contain necessary mathematics background)? Thanks a lot!
PS: I'm familiar with linear algebra and basic matrix analysis, but I don't know much about control theory since I majored in aerodynamics.
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Sometimes, you might need to apply other modal decomposition technique instead of POD. For example, DMD would be proper answer for some cases. 
You can find open source codes here:
and I found this comparison useful:
Comparison of optimized Dynamic Mode Decomposition vs POD for the shallow water equations model reduction with large-time-step observations
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At present i am using CAMRAD which does not address the subjected issue.
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Thanks a Ton Mr.Vitalii....
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Since most of the theoretical and conceptual designs of Single Stage to Orbit (SSTO) aircraft are depicted through Scramjet-based vehicles (such as the X-30 concept from the National Aerospace Plane Program - https://en.wikipedia.org/wiki/Rockwell_X-30), would it actually be possible (and also economically feasible) to reach an orbit (at least a LEO-grade orbit) using an air-breathing engine as a Scramjet or even an hybrid approach like the Turboramjet in the SR-71 ?
Best Regards.
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Dear Jorcy,
In principle it is possible for a SSTO scramjet-powered design to reach orbit.
However, in addition to numerous problems such as materials, propulsion, size and cost, as exemplified in the US National Aero-Space Plane Program, there is the problem of aerodynamic heating.
Using an air-breathing scramjet engine the vehicle would have to reach orbital velocity while flying within the atmosphere.
This flight profile leads to enormous amounts of aerodynamic heating which cannot be dealt with the present level of materials technology.
Best wishes,
N. Kehayas
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Hey everyone,
If I were to design a cabin on top of the drone chassis which holds the cargo (say 15 kg), How should one go about designing the chassis? Should it be a monocoque, steel frame, unibody, body on frame structure?
This is important in my opinion as the chassis should hold the battery (primary structural member) and the electronics involved to control the propeller rotation and resulting thrust. I would love to get as many opinions and feedback as possible. 
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The kind of UAV is important as James Whidborne has pointed - fixed / rotary / hybrid / etc.
Also just as important is the application - is it mission based, civilian goods transport, weather conditions used in, etc.
The kind of structure - truss, monocoque, stressed skin, steel frame, etc. - depends on the material/s you'll be using. The materials you'll use will depend on your priority:
- maximum flying mass without payload
- strength of the entire system
- usability and/or modularity
If you want maximum saving in weight, then you'd want to go with a monocoque truss type of design where the skin is of light material only functioning for profile and non of the load bearing.
If strength / durability is the priority then you'd want the entire structure be it trusses of surfaces to be strong. This could end up being very heavy.
If you want something that is easier to modify or have the detachable payload bay then you want to be genius with the entire design. You want something easy to install / uninstall, with minimum loss in overall performance, the entire structure of the UAV and the payload bay individually must be strong and the joints / load bearing elements much stronger.
Honestly, I personally feel that for almost any non military (or any such harsh) application, it's always best to have a combination of the 1st and the 3rd method explained above, i.e. a structure that is easy to setup, modular in design and yet only as heavy as it needs to be.
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I´m trying to model the SH60 (sea hawk helicopter) on FLIGHTLAB, but the paper "PROCEDURAL GUIDE FOR MODELING AND ANALYZING THE FLIGHT DYNAMICS OF THE SH-60B HELICOPTER USING FLIGHTLAB" from Roy C. Wagner has some missing information about horizontal stabilizer tables. Is there somebody who can help me to find it?
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Information on the UH-60 Black Hawk model is available on Howlett, J. J., "UH-60A Black Hawk engineering simulation program. Volume 1: Mathematical model", NASA-CR-166309, 1981. You would have to check if the horizontal stabilizer formulation and charts can be used.
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Many models of this aircraft were developed, does somebody know a source for geometrical, aerodynamic, and mass characteristics?
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Aircraft Dynamics: From Modeling to Simulation 1st Edition
by Marcello R. Napolitano (Author)
You can find detailed aero, mass, and prop data for your simulation 
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I am trying to think of simple general modifications that can be done to a conventional type UAV so that it flies with better stability during crosswind of about 13m/s.
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Cross wind consideration is required at the low speed operation such as take off and landing.At the conceptual and preliminary design stage, this effect needs to be considered to check the size of vertical tail
It depends on how big your aircraft is, there are the specified regulations on cross wind for UAV, LSA, VLA, FAR23, FAR 25 etc...Normally in Subpart B 
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Does anyone know of any study that provides/obtains experimental values for the slipstream contraction factor, and for the slipstream heigth of a rotor? I am trying to modulate the slipstream using the expression V=Vc+Vi+Vi*tanh(s*k/h), from Seddon's Basic Helicopter Aerodynamics, but I am not finding a way to evaluate k (wake contraction factor) and h (slipstream height). I think I only need the value for the upper rotor, so values from a single rotor might work. And if they were regarding small propellers (unmanned aircraft prop) it would be better. I believe I can get a value for k from theoretical assumptions (as Leishman does), but if I would like to try with experimental values.
Thank you.
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I doubt that it is convenient to use the value for a single rotor.
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How much the friction between the aircrafts wheels and the runway during landing, participate to the rising of the runway surface temperature? is it something like %20 or 30% ….. of the actual temperature of the asphalt. I know it will be a function of the aircraft's landing rate plain weight, length of the runway, the weather and the seasons, wind speed and so on.  
If you know any study have been carried out about this, any published paper or article that can be useful.
Many thanks
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Hello,
I agree there is a theoretical basis for this question.  However, given the short exposure time, small area of a tyre footprint and frictional load being only at the pavement surface, the impact is expected to be insignificant.
Certainly, when measuring runway surface temperatures, I have not observed a difference in surface temperature between the trafficked and un-trafficked areas of the runway.  In contrast, during hot weather, the (white) lines are always cooler than the (black) asphalt and the (even blacker) rubber build up in the touch down zone is usually hotter than the rest of the asphalt surface.
The only work I know of that is similar (but not the same) looked into the impact of jet exhaust on pavement temperature.  Citation shown below.  Although my questions around the practical significance are similar.
Cheers, Greg
Ahyudanari, Ervina, Nasir Shafiq, and Ibrahim Kamaruddin. "Identification and modelling process of defining temperature gradient in airport pavement." Aviation, vol. 18, no. 2, (2014): 72-79.
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I am looking for reference papers about rendez-vous methodology in the three bodies problem. 
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hi~ DO you have any progress on rendezvous at L2 point? I am interested on the topic too. One of my student will study redezvous at L2 point as his master thesis, may be we can discuss the problem, and exchange our ideas. I am also convinced that EML2 is ideal locations for human spaceflight.
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It could be related to fluid mechanics. To maintain the landing time, should i give more attention to lift or drag?
Any suggestion and opinion are welcomed. Thank you 
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Dear Lim
The distance travelled by a glider is a function of the glider lift-to-drag ratio and the height from which the glider will begin its flight, for both parameters the higher the better. It is not a function of its weight.
High lift-to-drag ratio is achieved with low drag. Subsonic drag is made of pressure drag, friction drag and drag due to lift. There is not a lot that can be done to reduce pressure drag. In any case, modern airfoils exhibit very low pressure drag. Low friction drag is a matter of maintening laminar flow over the wings, something quite possible with gliders. Drag due to lift is reduced with as much as structurally possible high aspect ratio wings.
Best wishes
N. Kehayas
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I like to know if any experiments carried out on NLF airfoil with ice accretion models.
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Dear Sir
I am attaching a paper.
with regards
Y D Dwivedi
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Suppose, a simplified model of the roll dynamics of an aircraft, which is represented by xdot(t) = A x(t) + B u(t), where the states are (phi, p) and the u is the aileron command **(neglecting the dutch-roll mode).
Due the fact that, the controller contains an integral term, the system dynamics is augmented to contain the state related to the integral of the error signal. Let's call it of Tau(t). Then, we have [xdot Tau_dot] = A_aug x_aug(t) + B_aug u(t).
So, the control law is given by u(t) = - K x_aug + K(1) Phi(ref), where K is the static gain of the controller. Which we can "interpreted" as K = [Kp Kd Ki] = [Proportional, Derivative , Integral] (I have all states to feedback).
As the output of actuator is limited and the controller has an integral term, I should implement an Anti-windup scheme to avoid the windup of integral term. So, what type of anti-windup do you suggest?
Thanks in advance.
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For digital implementations, I just stop integrating the error signal if the controller command signal, i.e. the input to the combined plant/actuator, saturates (i.e. hits +/- max). I know there are more sophisticated approaches, but I have always wondered why anything more than this is needed (?). 
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I am looking for papers/books presenting the regression equation between body size (body mass or wing length) and wingbeat frequency in hummingbirds. I'm aware of the two excellent publications below, and I try to get a hand on some of the old publications of Greenewalt, C. H.. Is there other publications that are addressing this relationship between body size and wingbeat frequencies in hummingbirds? I will need the regression equation to predict wingbeat frequency as a function of body size.
Altshuler, D. L., and Dudley, R. (2003). Kinematics of hovering hummingbird flight along simulated and natural elevational gradients. Journal of Experimental Biology 206, 3139-3147. doi:10.1242/jeb.00540
Altshuler, D. L., Dudley, R., Heredia, S. M., and McGuire, J. A. (2010). Allometry of hummingbird lifting performance. Journal of Experimental Biology 213, 725-734. doi:10.1242/jeb.037002
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I have only just seen the question, so apologies for the late response which I hope is still of some use. A long time ago I did the analysis based on the (then) available data, mainly from Greenewalt. The formulae are in the attached papers (I think one or other of these was the source for Robert Dudley's formula). There are definitely more numbers available now, but I doubt if adding them would change the scaling model very much. Note that the maximum frequencies are around 80 Hz: I never found any substantiated records of frequencies up to 200 Hz as claimed by some authors, but I have no first hand evidence either way.
There are a few things I'd advise you to note. First, the scaling for hummingbirds is very different from that for other birds, no doubt because of their small size, hovering flight and (probably most important) distinct wing morphology and wingbeat kinematics. Second, the scaling will give you an approximate indication of the frequency, but _only_ an approximation. At the lightest size range of hummingbirds (2-3g)  the hovering frequency can vary between around 35 and 80Hz, depending on the species, while the scaling equation would predict around 50Hz.  In principle better estimate could be made by adding the wingspan and wing area to a multiple regression formula, but the dataset I have is much too small to compute this with any accuracy. Third, according to the dataset (and sometimes individual sources such as Greenewalt) frequency seems to be highly variable within a species, and might vary for instance with gender, size/mass or relative wing size (or some of the measurements may be inaccurate). Other factors will be involved as well, including altitude, environmental conditions, body condition, whether recently fed, and so on.  I am not sure there are enough data out there to look seriously at the problem - there certainly were not when I was looking at this - but it would be an interesting study.
Finally - as I hope the papers explain - there is no one single biomechanical factor that determines frequency as a function of size. Rather, the perceived scaling (allometry) is a summary of the evolution of wing design and frequency within a variety of constraints, which will have different significance on birds with different habits. So I have always been cautious about reading too much biological meaning, or indication about the biology of an individual species, into a scaling formula.
I hope this is of use to you. If you still need copies of the Greenewalt data, or relevant bits of his book and papers, let me know.
Regards
Jeremy Rayner
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I just want to know what people usually do to measure the circulation or vortex strength in water or wind tunnel (like HWA or PIV, etc.), especially in some cases where the "boundary" of a vortex is not that clear, and the circulation can vary a lot when different boundaries are chosen. Sumner presented his data of circulation, sadly I didn't found his method of doing it in his paper. Here's Sumner's JFM paper: Sumner D, Price S J, Paidoussis M P. Flow-pattern identification for two staggered circular cylinders in cross-flow[J]. Journal of Fluid Mechanics, 2000, 411: 263-303.
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 PIV with markers inserted in liquid combined with laser sheet optics should work.
For the air flow Schlieren Photography may work.
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hi dear researchers,
i want to model UAV aerodynamic,
i use relations in part 6 roskam  or relation in performance books?
if any researcher have another source please send me.
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My answer is very simple dear Mohammad. It is a hell of a job to calculate with sub-mm accuracy where a ballistic missile will have its impact. But my dear fella, you are not interested in fighter planes or rockets are you? No War but Peace ain't it!
Then I can help you. Just Google the term:"Realism of aerodynamic models", and you will find hundreds of aerodynamic models and validations of them, which show even how realistic the flight of a bumblebee can be simulated. Nature is great!
Go ahead and enjoy the wonders of aerodynamics in nature modeled as well as observed. As I suggested I cannot help you with the aerodynamics for offensive weaponry. Ask en American, they know all about it!.
I am a peacefull European. Unles you want to destroy the House of Saoud and their secret army the IS in Iraq, Syria, Libia and Nigeria or wherever thes terrorists destroy innocent people and inoocent human life..I will help you with that for sure. I hate IS!
Cheers,
Frank
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see attachment please.
I have successfully come up with a new helicopter design that I call the NOTA MRH (NO TAil Mono Rotor Helicopter). The picture shows it's basic design. This helicopter does not need a tail rotor for torque reaction. The person flying this helicopter will only mind about the single main rotor cause that's the only rotor on the helicopter. It can work well for stealth helicopters. It is not a Mono copter or Coaxial helicopter nor Tandem helicopter and can easily be fitted in a space capsule if required for future landing.
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My suspicion is that 1) the small radius rotor would have to rotate at an unacceptably high rate to counter the torque by the main rotor, 2) the resulting turbulence would likely affect the performance of the main rotor, and 3) it would be a very wasteful design, as the small rotor would not contribute at all to lift, so all the energy spent on making it rotate is wasted.
The reason why the standard helicopter design works is because the small rotor is at the end of a large moment arm. The reason why the coaxial design works is because the two counterrotating rotors both contribute to lift.
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Does it build asymetrically? How does the build up of ice cause a rotor blade to become unbalanced, if it is not asymetrical?
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I might be wrong, but ice should not be able to form on a blade completely equally, which means one blade would be at least heavier than the other. Also rotor blade is balanced for its specific shape and size, and forming of ice changes that.  
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How can the propeller slipstream-induced yawing effect on a General Aviation aircraft be estimated with only limited geometric information available?
Any references to existing literature dealing with this would be helpful.
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There's also an ESDU data sheet dedicated to Propeller effects, ESDU 85015.  Even though the title says effects on lift and drag, it also includes methods that can be extended to yaw.
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For finding transfer function of aircraft  we are finding 6 equations of motions then longitudinal and lateral equations of motions then linearization then statespace matrix then transfer function and used it in closed loop system
if we take a similar transfer function fraction equation as numerator and denominator of our own and use it in closed loop system 
i mean to ask that if we take similar fraction or transfer function then simulate it in matlab the if we getting the approximate results when compared with original transfer function, then what is the use of dynamics why we working very hard for dynamics of aircraft and uav or quadrotor? is it just for sake of proof?but i think main thing is to design different controllers like linear and nonlinear controllers?
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I just want to what Robert has said above. Modeling the plant (Aircraft or anything you want to control) is the corner stone of the controller design process. As much as the model is close to the physical plant eliminating any uncertainties, as much the controller can be made robust  in terms of performance and stability.
This basic understanding has led to many important work to:
1- Produce "High Fidelity Models" that mimic the physical plant. Normally, they are nonlinear and covers the actuators and sensors plus any structural dynamics that will impact the aerodynamic model.
2- The nonlinear model either is used directly to develop the nonlinear controller using design methods such as Sliding Mode Control (SMC) or Backsteping or Nonlinear Dynamic Inversion.
3- Else, the nonlinear model is linearized by using Taylor Expansion or using non-local methods such Linear Parameter Varying (LPV) method and subsequently linear design methods are used to design the controller such H-infinity or mu-Synthesis or other methods.
4- To ensure a more robust control, the propulsion is integrated with the airframe (rigid dynamics) to base the design on an integrated flight and propulsion (IFP)
5- Once the design is over, what you will load into the computer is the controller and not the model as the physical plant will replace the model used during the design. So if the model was comprehensive =  "High Fidelity Model", then the controller will produce the results during flight simulation which are same as during desktop simulation.
I hope the above sequence and last point (#5) helps to clarify the confusion.
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In response to a negative step command of the elevator, the aircraft first goes down, and then goes up.
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Let's say you deflect the elevator 6° (downwards) for a pitch down maneuver. Eventually the increased lift at the elevator leads to a negative pitching moment and thus to a ptich down because the center of gravitiy is in front of the elevator. But initially the increased lift leads to a gain of height because your aircraft generates more lift just befor the pitching moment sets in. 
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I would like to chalk down a list of methods for designing an FMP system.
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My previous research used particle swarm optimization for flight scheduling
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I am working on improving cockpit automation interfaces and will be using a PC based simulation as part of that effort. I am considering using Microsoft’s FSX, Flight Gear, X-Plane or Prepar3D. I’m leaning toward Flight Gear as it is open source and may be easier to develop interfaces with it using custom software. I wanted to ask other researchers what opinion they have regarding the suitability of these platforms for academic research especially when failure simulations will be created?
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I don't know much about the other sims, but X-Plane lets you access simulation data via UDP. Two of my students wrote an interface which we could use to get sim outputs and write sim inputs. The number of accessible states / parameters is fairly comprehensive.
You'll find information about the protocol at http://www.nuclearprojects.com/xplane/xplaneref.html
Cheers,
Marc
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Because I saw an illustration showing this situation.
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On Earth's moon? Surely not, it lacks the atmosphere.
However, you may have seen a notice that NASA looks into exploring Titan (Saturn's largest moon) with aeronautical devices (balloons and quadrotors). This would work, because Titan has a dense atmosphere (surface pressure about 146 kPa).
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What is the highest wingbeat frequency (WBF) recorded for hummingbirds during hovering? To my knowledge the highest is 80 wingbeat per sec for the Bee hummingbird (Calypte helenae) (Greenewalt 1960). Are there publications that I'm not aware of with registrations of higher WBF for hummingbirds hovering?
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According to the Handbook of the birds of the World, Volume 5, wingbeat rates of up to 200 per second have been recorded in Rufous Hummingbirds (Selasphorus rufus) and Ruby-throated Hummingbird (Archilochus colubris), albeit during courtship. Sadly, the HBW does not give orginal sources in the text and one has to scan through the whole reference section to find them. Alternatively, you might contact the author of the Hummingbird chapter (Prof. Schuchmann's email is available through www.zfmk.de). I hope this information helps.
Kind regards
Darius
 
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There are well established manuals on flying/handling qualities for fixed-wing aircraft as well as for helicopters. Does anyone know if there exists similar documentation for the UAVs?
In designing flight control systems (FCS) for an air vehicle one has to consider HQ/FQ in order to meet specs of real FCS. Where can one see a set of HQ/FQ for all types of UAV (fixed wing, quad rotors, helicopters, etc.)?
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I see your question lately, sorry; find some references I used on my R&D activity in the field of UAV design.
Evolution of Flying Qualities Analysis: Problems for a
New Generation of Aircraft by Christopher Cotting (USA – 2010)
Static-Stability Analysis of a Unmanned Airplane as a
Flexible-Body by Oscar E. González and al. (Venezuela – 2010)
Evaluation of Stability and Flying Qualities of a Light Unmanned Aerial Vehicle (UAV) - by Mikael Samuelsson (Sweden -2012)
Hope that it will help you; feel free to contact me if necessary.
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I am trying to write a project proposal and I am having a problem referencing my proposal. Thing is I know things like dust etc can cause some damage to propellers which might lead to dents and cracks and etc, but what I need is research papers that prove this Where can I find them?
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Unless there is specific research looking at the effects of debris/precipitation damage, you're more likely to find relevant resources within maintenance documents or accident reports where such events have been reported. For example, search "CASA propeller stone damage" for relevant information in the first listed article from the Flight Safety magazine. At the more severe end of the spectrum, an academic at Loughborough University has researched the aerodynamics of battle damaged wings, which may have some relevance to your proposal - search the AIAA database for related papers.
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Boeing 737 aircraft have recently been retrofitted with split blended winglets. How they result in reduction in drag, thereby fuel savings?
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Winglets are used to cut down the wing tip vortices which result in induced drag....the formula for the total drag = profile drag + induced drag
In a cruise condition, Thrust = Drag, which means lesser thrust required for lesser drag....thereby saving the fuel....
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I'm looking for advice and references regarding the current state of the art for detecting landing and takeoff in fixed-wing micro UAVs. Hand launching is particularly of interest, as it is the most likely launch mode for micro UAVs.
Due to the low flight airspeeds of micro UAVs, pitot tube and GPS data are noisy and difficult to rely upon. One approach would be to add pressure sensors to detect contact with the ground or a human hand, but this is not an easily workable approach if cost, weight, and complexity are to be kept down. Ideally, we would like a generic implementation which uses the inertial gyroscopic and accelerometer sensors to detect takeoff and landing, but in my literature searches I haven't yet found anything along these lines.
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Have you considered detecting takeoffs based on the horizontal acceleration profile? As the fixed wing UAV leaves the ground, there is a very clear dip on the horizontal acceleration of the aircraft as it leaves the ground. Of course, there are several ways to obtain the acceleration profile of your aircraft given the payload you specified, and some may not provide you with enough resolution or accuracy to give you a takeoff indication as close to the actual time as you may require. But overall this is a sound method that even in the worst case scenarios should be part of a validation process to determine if other methods are making valid takeoff determinations.