Innovative rotor blades - Technology streamsThe scope of this subproject is the development and assessment of active and passive technologies based on a two

streams strategy. The first one concerns the continuation of the research activities performed within the framework of

the FP6 FRIENDCOPTER Integrated Project on active twist technology and the second one based on variation of

rotor speed, optimum planform and active rotor system preserving rotor aerodynamic performance and dynamic

attributes to maintain stall envelope and reduce vibration. 

Active Twist

It concerns the development of a full scale, active

twist blade segment based on integrated piezoelectric actuators (see diagram on the left) to allow the blade shape to

be changed in flight to improve performance and/or reduce rotor generated noise. Analysis will be performed to

assess future exploitation challenges, benefits in line with GRC1 objectives and airworthiness / safety evaluation. The

expected TRL level at the end is planned to be 4. 

Active Gurney Flap

This dynamic blade control surface implements the same aerodynamic concept as steady Gurney flaps used on non

rotating parts of some helicopters and airplanes. It will be thoroughly tested in 2D wind tunnel and new CFD

modelling techniques have been developed to study the operation and performance. An active Gurney flap system is

under development for a full scale main rotor blade and additional partners have been selected to design,

manufacture and supply the actuation systems required for model testing and at full scale on a whirl tower. At the end

of the program TRL 5 is expected to be achieved

Passive rotor optimisation

This development is based on the use of state of

the art, multi-objective, genetic algorithms to assess all possible combinations of blade chord and twist distribution

and additional blade features e.g. anhedral (see diagram on the right). An optimised full-scale blade aiming to

maximise performance and minimise noise will be tested on a whirl tower. 

Smart helicopter thanks to active rotor blades March 6, 2013 Active systems in helicopter rotor blades can adapt the blades' aerodynamic properties to local airflow conditions. The use of such systems leads to lower fuel consumption, increased maximum speed and reduced noise and vibration. A French PhD researcher at the University of Twente, Alexandre Paternoster, has developed a method for implementing these innovative systems, thereby bringing the smart helicopter one step closer. Ads by Google BK117 For Sale - We Have Many BK117 Helicopters For Sale or Lease. Contact us Now! - www.airwork.co.nz Dr Paternoster's research is part of the European "Clean Sky" Joint Undertaking, which aims to increase the efficiency of air transport. The researchers involved in this Joint Undertaking are currently focusing mainly on active flap systems in helicopter rotor blades. The integration of these systems is no easy matter, given the enormous forces generated by rotor blade rotation, and the durability and reliability requirements involved. Using software simulations and a wind tunnel, Alexandre Paternoster examined the selection process for these actuators and determined the optimal design for such systems. His aim was to make them easier to integrate. Dr Paternoster concluded that mechanisms based on piezoelectric materials are capable of meeting these requirements. He feels that the devices best suited for use in rotor blades are the d33 patch actuators from Physik Instrumente. Gurney flap Of all the active rotor systems currently under development, the Active Gurney Flap has been selected in the framework of the Clean Sky Joint Undertaking's Green Rotorcraft Integrated Technology Demonstrator. Extending the Gurney flap during the return movement of the rotor blade improves the blade's lift and overall performance. This technology is already in an advanced stage of development. Alexandre Paternoster's goal was to find the most efficient design for a Gurney Flap. In addition to taking account of the various aerodynamic forces involved, he had to identify realistic combinations of extension levels for the mechanism, flow direction and airspeed. On the basis of a piezoelectric actuator, the design was optimized to generate the maximum amount of movement and actuator power. The result is a "Z"-shaped structure. This mechanism amplifies the extension generated by the piezo element into a relatively large movement. Prototype Alexandre Paternoster's aerodynamic model is combined with a multi-body simulation and a simulation that is used to assess the performance of the mechanism in practice. The mechanism's performance is sufficient to extend and retract the Gurney flap while it is

exposed to the powerful forces generated by the air flow. He concluded his study by creating a prototype of this z-shaped mechanism. This prototype made it possible to obtain experimental validation of the movements within the mechanism. The prototype performs superbly, and can be easily integrated into helicopter rotor blades. It also demonstrates the potential of piezoelectric material in actuation mechanisms. The development of such innovative technologies provides actuation system solutions for the highly demanding aerospace industry. The next generation of smart helicopters will soon be taking to the skies. The doctoral thesis is titled "Smart Actuation Mechanisms For Helicopter Blades". Provided by University of Twente 

Read more at: http://phys.org/news/2013-03-smart-helicopter-rotor-blades.html#jCp

Power generation from speed breakers

Posted Date: 11-Jun-2012 Category: Mechanical Projects Author: rahul srivastava Member Level: Silver Points: 25 (Rs 13)

B.tech final year projects give opportunity to students to do some breakthrough

work.Increasing demand of energy adds need of identifying non conventional

resources of energy. In this article I will explain about Power generation from

speed breaker and all the possible mechanism required for it.

For completion of B.tech final year curriculum every student has to complete an engineering project.

I along with my group members have gone through various topics and finally we selected power

generation from speed breakers

This project is in starting phases and in many places of world research is going on this topic. We have

decided to complete it by simple methodology yet effective.

Principle Fundamental

This project is simply based on utilising potential energy of a vehicle passing over a road breaker by

converting it to electrical energy. This electrical energy can be store in batteries or can be directly

use to light up street light or traffic signals. 

By using such system which can convert potential energy of a vehicle in to electrical energy we can

generate a large amount of energy. This large amount of electricity will reduce the burden of

demands from conventional resources.

System Required

To facilitate the power generation from speed breaker we need an assembly of different system. We

can classify this system as-

Damper system

Motion conversion system

Electricity converter 

To make this conversion possible the whole plan of action is like as the vehicle passes over the

breaker of the system damper system a system will provide support to speed breaker and due to

weight of the vehicle breaker will go down and motion conversion system will convert downward

linear motion into rotary motion. This rotator motion will be feed to energy conversion system. It will

convert mechanical energy to electrical energy.

Damper System

Damper system is required to support the speed breakers. Once the speed breakers are pushed

down then a damper system will be required to push the speed breakers up again to its original

state. They are also required to absorb the shocks produced during the passage of vehicles over the

speed breakers.

Motion conversion system

Motion conversion system converts linear vertical motion into rotary motion. To complete this

conversion of motion, a rack and pinion mechanism is applied. Rack and pinion mechanism consists

of two parts. First is rack, it is the flat, toothed part, performing linear motion. Second is pinion, it is a

gear in wheel form, producing rotary motion. So this conversion system is called motion conversion

system.

Energy Conversion System

Energy conversion system is required to convert mechanical energy into electrical energy. Rotary

motion is obtain as the output of pinion (or of gear box), which is coupled with a dynamo. Dynamo

generates electricity with the help of input rotary motion. The electrical energy is obtained as the

output of the dynamo. In addition to this, a stepper motor is coupled to the rotary motion obtain from

the other set of rack and pinion. Stepper motor is applied to enhance the generated power. In a

dynamo electricity is generated by cutting of magnetic lines by a conductor.

Energy Estimation

When the vehicle moves over the speed breaker it reduces its speed. As these breakers have a little

height it gains an increase in its potential energy. A vehicle weighing 1,000 kg passes over the

system it pushes the damper to a depth of 10 cm it can produce approximately 0.98 kilowatt power

(ideally). So from one such speed-breaker on a busy highway, where about 100 vehicles pass every

minute, about one kilo watt of electricity can be produced every single minute. This project needs a

lot research work as it can be proved a non conventional resource of energy.

Ultrasound can now monitor the health of your car engine December 10, 2012 A system that uses ultrasound technology to look inside car engines could lead to more efficient engines – and huge fuel savings for motorists. Ads by Google Engine Lubrication Oil - Manufacturer & Supplier of Quality Engine Lubrication Oil. Call Now! - dpzint.co.in/09810945557 Ultrasound scans have long been a fundamental tool in healthcare for looking inside the human body, but they have never before been put to use in testing the health of a modern combustion engine. In the University of Sheffield's Department of Mechanical Engineering, Rob Dwyer-Joyce, Professor of Lubrication Engineering, has devised a method of using ultrasound to measure how efficiently an engine's pistons are moving up and down inside their cylinders. "There is a real urgency, now, to improve energy consumption in cars," says Professor Dwyer-Joyce. "Our method will allow engine manufacturers to adjust lubrication levels with confidence and ensure they are using the optimum level for any particular engine, rather than over-lubricating to ensure engine safety. The energy used by the piston rings alone amounts to around 4p in every litre of fuel – there is a lot at stake in getting the lubrication right." The seal between piston rings and cylinder is the most important seal in the entire engine and understanding how the lubricant works inside this sealed chamber is crucial for improving the fuel efficiency of the engine. The movement of the pistons is what drives the car forward. Car manufacturers have to calculate how much oil will allow the piston to move efficiently. Too much oil is wasteful and ends up getting burnt in the engine – increasing emissions, while too little will result in wear from the two moving parts rubbing against each other. Because cylinders are enclosed spaces, it is not easy to test what is going on inside. Computer models don't effectively allow for changes as an engine speeds up and gets hotter, and more invasive methods – cutting open the cylinder – interfere too much with the mechanism to get an accurate test result. The Sheffield team are measuring the lubricant film by transmitting ultrasonic pulses through the cylinder wall from sensors attached to the outside. The reflections from these pulses can then be recorded and measured. The research is part of a project funded by the Engineering and Physical Sciences Research Council. It has included collaboration with Loughborough, which is overall leader on the project, and Cranfield Universities, and a host of automotive industry manufacturers and suppliers. The research team at Loughborough is investigating the piston-cylinder dynamics and tribological modelling, the development of predictive tools, advanced cylinder liners and surface laser texturing, and the direct measurement of friction, whilst the team at Cranfield have been studying the micro-scale interaction between the piston rings and the cylinder. The team is ready to commercialise this technology and is looking for industrial partners who might be interested in pursuing the approach. "Our system could provide major efficiency savings in car engines, but it could also be used on the larger diesel engines in deep water marine vessels, some of which use up to 1 tonne of oil each day," adds Professor Dwyer Joyce. More information: Piezo-electric sensors to monitor lubricant film thickness at piston-cylinder contacts in a fired engine, by R. S. Mills, E. Y. Avan and R. S. Dwyer-Joyce, is currently published Online First in the Journal of Engineering Tribology, published by SAGE on behalf of the Institution of Mechanical Engineers. It will appear in a special edition of the Journal in February 2013. Provided by University of Sheffield 

Read more at: http://phys.org/news/2012-12-ultrasound-health-car.html#jCp

Pertenece a: University of Twente Publications  

Descripción: Successful rotorcrafts were only achieved when the differences between hovering flight conditions and a stable forward flight were understood. During hovering, the air speed on all helicopter blades is linearly distributed along each blade and is the same for each. However, during forward flight, the forward motion of the helicopter in the air creates an unbalance. The airspeed is increased for the blade passing in the advancing side of the helicopter, while it is reduced in the retreating side. Moreover, when each blade enters the retreating side of the helicopter, a reverse flow occurs around the profile where the blade speed is lower than the forward speed of the helicopter. The balance of a rotorcraft is solved by a cyclic pitch control, but trade-offs are made on the blade design to cope with the great variety of aerodynamic conditions. A smart blade that would adapt its characteristics to this large set of conditions would improve rotorcrafts energy efficiency while providing vibration and noise control. Smart rotor blades systems are studied to adapt the aerodynamic characteristics of the blade during its revolution and to improve the overall performances. An increase in the lift over drag ratio on the retreating side has been studied to design a blade with better aerodynamic efficiency and better stall performances in the low-speed region. The maximum speed of a rotorcraft is limited by the angle of attack that the profile can sustain on the retreating side before stall. Therefore, increasing the maximum angle of attack that a profile geometry can sustain increases the rotorcraft flight envelope. Flow asymmetry and aerodynamic interaction between successive blades are also investigated to actively reduce vibrations and limit noise. These improvements can be achieved by deploying flaps, by using flow control devices or by morphing the full shape of the profile at a specific places during the blade revolution. Each of the listed methods has advantages and disadvantages as well as various degrees of feasibility and integrability inside helicopter blades. They all modify the aerodynamic characteristics of the profile. Their leverage on the various aerodynamic effects depends on the control strategy chosen for actuation. Harmonic actuation is therefore studied for active noise and vibration control whereas stepped deployment is foreseen to modify the stall behaviour of the retreating side of the helicopter. Helicopter blades are subjected to various force constraints such as the loads from the complex airflow and the centrifugal forces. Furthermore, any active system embedded inside a rotor blade needs to comply with the environmental constraints to which a helicopter will be subjected  during its life-span. Other concerns, like the power consumption and the data transfer for blade control, play an important role as well. Finally, such a system must have a life-time exceeding the life-time of a rotor blade and meet the same criteria in toughness, reliability and ease of maintenance. Smart system is an interplay of aerodynamics, rotor-mechanics, material science and control, thus a multidisciplinary approach is essential. A large part of the work consists in building processes to integrate these domains for investigating, designing and testing smart components. Piezoelectric actuators are a promising technology to bring adaptability to rotor blades. They can be used directly on the structure to actively modify its geometry, stiffness and aerodynamic behaviour or be integrated to mechanisms for the deployment of flaps. Their large specific work, toughness, reliability and small form factor make them suitable components for integration within a rotor blade. The main disadvantage of piezoelectric actuators is the small displacement and strain available. Amplification mechanisms must be optimised to produce sufficient displacement in morphing applications. Smart actuation systems placed inside rotor blades have the potential to improve the efficiency and the performances of tomorrow's helicopters. Piezoelectric materials can address many of the challenges of integrating smart components inside helicopter blades. The key aspect remains the collaboration between various domains, skills and expertise to successfully implement these new technologies.

Autor(es): Paternoster, A.R.A. -  Loendersloot, R. -  Boer de, A. -  Akkerman, R. - 

Gurney flapFrom Wikipedia, the free encyclopedia

A gurney flap shown on the underside of a Newman airfoil (from NASA Technical Memorandum 4071).

The Gurney Flap (or wickerbill) is a small flat tab projecting from the trailing edge of a wing. Typically it is set

at a right angle to the pressure side surface of the airfoil,[1] and projects 1% to 2% of the wing chord.[2] This

trailing edge device can improve the performance of a simple airfoil to nearly the same level as a complex high-

performance design.[3]

The device operates by increasing pressure on the pressure side, decreasing pressure on the suction side, and

helping the boundary layer flow stay attached all the way to the trailing edge on the suction side of the airfoil.

[4] Common applications occur in auto racing,helicopter horizontal stabilizers, and aircraft where high lift is

essential, such as banner-towing airplanes.[5]

Contents

[hide]

1 History

2 Theory of operation

3 Helicopter applications

4 See also

5 References

6 External links

[edit]History

The "variable lift airfoil" shown in Figure-1 of the 1935 E.F. Zaparka patent, U.S. Patent Re19,412. It is a movable microflap,

similar to the fixed Gurney flap.

A Gurney flap on the trailing edge of the rear wing of a Porsche 962.

The original application, by automobile racing icon Dan Gurney, was a right-angle piece of sheet metal, rigidly

fixed to the top trailing edge of the rear wing on his open wheel racing cars of the early 1970s. The device was

installed pointing upwards to increase downforcegenerated by the wing, improving traction.[4] He field tested it

and found it allowed a car to negotiate turns at higher speed, while also achieving higher speed in the straight

sections of the track.[6]

The first application of the flap was in 1971,[7] after Gurney retired from driving and began managing his own

racing team full-time. His driver, Bobby Unser, had been testing a new Gurney designed car at Phoenix

International Raceway, and was unhappy with the car's performance on the track. Gurney needed to do

something to restore his driver's confidence before the race, and recalled experiments conducted in the 1950s

by certain racing teams with spoilers affixed to the rear of the bodywork to cancel lift. (At that level of

development, the spoilers were not thought of as potential performance enhancers—merely devices to cancel

out destabilizing and potentially deadly aerodynamic lift.) Gurney decided to try adding a "spoiler" to the trailing

edge of the rear wing.[8] The device was fabricated and fitted in under an hour, but Unser's test laps with the

modified wing turned in equally poor times. When Unser was able to speak to Gurney in confidence, he

disclosed that the lap times with the new wing were slowed because it was now producing so

muchdownforce that the car was understeering. All that was needed was to balance this by adding additional

downforce in front.[9]

Unser realized the value of this breakthrough immediately and wanted to conceal it from the competition,

including his brother Al. Not wanting to call attention to the devices, Gurney left them out in the open.[10] To

conceal his true intent, Gurney deceived inquisitive competitors by telling them the blunted trailing edge was

intended to prevent injury and damage when pushing the car by hand. Some copied the design, and some of

them even “improved” it by pointing the flap downwards, which actually hurt performance.[11]

Gurney was able to use the device in racing for several years before its true purpose became known. Later, he

discussed his ideas with aerodynamicist and wing designer Bob Liebeck of Douglas Aircraft Company. Liebeck

tested the device, which he later named the “Gurney flap,” and confirmed Gurney’s field test results using a

1.25% chord flap on a Newman symmetric airfoil.[12] His 1976 AIAA paper (76-406) “On the design of subsonic

airfoils for high lift” introduced the concept to the aerodynamics community.[13] The Gurney flap is the first

aerodynamic development made in automobile racing that has been transferred to aircraft engineering.[11]

Gurney assigned his patent rights to Douglas Aircraft,[9] but the device was not patentable, since it was

substantially similar to a movable microflap patented by E.F. Zaparka in 1931, ten days before Gurney was

born.[9][14] Similar devices were also tested by Gruschwitz and Schrenk[15] and presented in Berlin in 1932.[16]

[edit]Theory of operation

The Gurney flap increases the maximum lift coefficient (CL,max), decreases the angle of attack for zero lift (α0),

and increases the nosedown pitching moment (CM), which is consistent with an increase in camber of the

airfoil.[4] It also typically increases the drag coefficient (Cd),[17] especially at low angles of attack,[18] although for

thick airfoils, a reduction in drag has been reported.[19] A net benefit in overall lift to drag ratio is possible if the

flap is sized appropriately based on the boundary layer thickness.[20]

The Gurney flap increases lift by altering the Kutta condition at the trailing edge.[4][6] The wake behind the flap is

a pair of counter-rotating vortices that are alternately shed in a von Kármán vortex street.[21] In addition to these

spanwise vortices shed behind the flap, chordwise vortices shed from in front of the flap become important at

high angles of attack.[5]

The increased pressure on the lower surface ahead of the flap means the upper surface suction can be

reduced while producing the same lift.[21]

[edit]Helicopter applications

Double Gurney flaps on a Bell 222U helicopter

Gurney flaps have found wide application on helicopter horizontal stabilizers, because they operate over a very

wide range of both positive and negative angles of attack. At one extreme, in a high-powered climb, the

negative angle of attack of the horizontal stabilizer can be as high as -25°; at the other extreme, in autorotation,

it may be +15°. As a result, at least half of all modern helicopters built in the West have them in one form or

another.[22]

The Gurney flap was first applied to the Sikorsky S-76B variant,[11] when flight testing revealed the horizontal

stabilizer from the original S-76 did not provide sufficient lift. Engineers fitted a Gurney flap to the NACA 2412

inverted airfoil to resolve the problem without redesigning the stabilizer from scratch.[11] A Gurney flap was also

fitted to the Bell JetRanger to correct an angle of incidence problem in the design that was too difficult to

correct directly.[11][22]

The Eurocopter AS355 TwinStar helicopter uses a double Gurney flap that projects from both surfaces of

the vertical stabilizer. This is used to correct a problem with lift reversal in thick airfoil sections at low angles of

attack.[11] The double gurney flap reduces the control input required to transition from hover to forward flight.[22]

[edit]See also

Lift (force)

[edit]References

1. ̂  Van Dam, C.P.; Yen, D.T.; Vijgen, P. (1999). "Gurney flap experiments on airfoil and wings". Journal of

Aircraft(0021-8669) 36 (2): 484–486. doi:10.2514/2.2461. Retrieved 2007-07-05. "These devices provided

an increased region of attached flow on a wing upper surface relative to the wing without the flaps."

2. ̂  Storms, B.L.; Jang, C.S. (1994). "Lift Enhancement of an Airfoil Using a Gurney Flap and Vortex

Generators". Journal of Aircraft 31 (3): 542–547. doi:10.2514/3.46528. Retrieved 2007-07-05. "One

candidate technology is the Gurney flap, which consists of a small plate, on the order of 1-2% of the airfoil

chord in height, located at the trailing edge perpendicular to the pressure side of the airfoil."

3. ̂  Giguere, P.; Lemay, J.; Dumas, G. (1995). "Gurney flap effects and scaling for low-speed airfoils". AIAA

Applied Aerodynamics Conference, 13 th, San Diego, CA, Technical Papers. Pt. 2. pp. 966–976. "through

the proper use of Gurney flaps, the aerodynamic performance of a simple design, easy-to-build airfoil can

be made practically as well as those of a modern, high performance, complex design."

4. ^ a b c d Myose, R.; Papadakis, M.; Heron, I. (1998). "Gurney flap experiments on airfoils, wings, and

reflection plane model".Journal of Aircraft 35 (2): 206–211. doi:10.2514/2.2309. Retrieved 2007-07-05.

"Race-car driver Dan Gurney used this flap to increase the downforce and, thus, the traction and potential

cornering speeds generated by the inverted wings on his race cars."

5. ^ a b Troolin, D.R.; Longmire, E.K.; Lai, W.T. (2006). "Time resolved PIV analysis of flow over a NACA 0015

airfoil with Gurney flap" (PDF). Experiments in Fluids 41 (2): 241–

254.Bibcode 2006ExFl...41..241T. doi:10.1007/s00348-006-0143-8. Retrieved 2007-07-07. "...the

intermittent shedding of fluid recirculating in the cavity upstream of the flap, becomes more coherent with

increasing angle of attack.... Comparison of flow around ‘filled’ and ‘open’ flap configurations suggested that

[this] was responsible for a significant portion of the overall lift increment."

6. ^ a b Jang, C.S.; Ross, J.C.; Cummings, R.M. (1998). "Numerical investigation of an airfoil with a Gurney

flap". Aircraft Design 1(2): 75–88. doi:10.1016/S1369-8869(98)00010-X. Retrieved 2007-07-06. "Liebeck

stated that race car testing by Dan Gurney showed that the vehicle had increased cornering and straight-

away speeds when the flap was installed on the rear wing."[dead link][dead link]

7. ̂  Troolin,, Daniel R.; Ellen K. Longmire, Wing T. Lai (2006-06-26). "The Effect of Gurney Flap Height on

Vortex Shedding Modes Behind Symmetric Airfoils". 13th Int. Symp. on Applications of Laser Techniques to

Fluid Mechanics.

8. ̂  Wagner, Jan R. (2004). "The 2004 Art Center Car Classic (Part Two): Dan Gurney on Racing and the

“BLAT” Effect". Auto Matters. Retrieved 2007-07-06. "'And I remembered having spent a lot of time with

these little tabs on the back, or spoilers and so forth, and I thought to myself – well, I wonder if one would

work on a wing? We already had wings on these in 1971. Sure enough, that was the beginning of the

Gurney flap.'"

9. ^ a b c Howard, Keith (2000-09). "Gurney Flap". Motorsport Magazine. "Once Gurney had confirmed they

were alone, Unser told him the rear was now so well planted that the car was pushing (understeering)

badly, hence the poor lap times."

10. ̂  Unser, Bobby (2004). Winners Are Driven. New York: Wiley. p. 15. ISBN 0-471-64745-4. "Dan told me to

relax. Leave them in the open. Don't bring attention to them."

11. ^ a b c d e f Houghton, E. (2003). Aerodynamics for Engineering Students. Boston: Butterworth Heinemann.

pp. 500–502. ISBN 0-7506-5111-3. "So successful was this deception that some of his competitors

attached the tabs projecting downwards to better protect the hands."

12. ̂  Myose, R.; Heron, I.; Papadakis, M. (1996). "Effect of Gurney flaps on a NACA 0011 Airfoil". AIAA Paper:

96–0059. Retrieved 2007-07-08. "Liebeck conducted wind tunnel tests on the effect of a 1.25% chord

height Gurney flap. He used a Newman-type airfoil, which had an elliptic nose and a straight line wedge for

the rear section."

13. ̂  Schatz, M.; Gunther, B.; Thiele, F. (2004). "Computational Modeling of the Unsteady Wake Behind

Gurney Flaps". AIAA Paper 2417. Retrieved 2007-07-06. "The first theoretical investigations were published

by Liebeck who introduced the concept of trailing edge devices to aircraft aerodynamics."

14. ̂  Sobieczky, H. (2003). "Gurney Flaps in Transonic Flows".Iutam Symposium Transsonicum IV. Henning

Rosemann and Kai Richter. Berlin: Springer. p. 165. ISBN 1-4020-1608-5. "Gurney flaps are known already

since 1931, when they were first patented by Zaparka (USA)."

15. ̂  Zerihan, J.; Zhang, X. (2001). "Aerodynamics of Gurney flaps on a wing in ground effect". AIAA

Journal 39 (5): 772–780.Bibcode 2001AIAAJ..39..772Z. doi:10.2514/2.1396. Retrieved 2007-07-07.

16. ̂  Gruschwitz, Eugen; Oskar Schrenk (1932-10-28,). "Über eine einfache Möglichkeit zur Auftriebserhöhung

von Tragflügeln (A simple method for increasing the lift of airplane wings by means of

flaps)" (PDF). Zeitschrift für Flugtechnik und Motorluftschiffahrt. vol. 23, no. 20. Wissenschaftliche

Gesellschaft für Luftfahrt (21st 1932 Berlin) (Translation by Dwight M. Miner ed.). Washington, June

1933: National Advisory Committee for Aeronautics. pp. 597–601. NACA-TM-714. "The problem is to

create, in landing, a region of turbulence on the lower side of the wing near the trailing edge by some

obstacle to the air flow."

17. ̂  Jang, C.S.; Ross, J.C.; Cummings, R.M. (1992)."Computational evaluation of an airfoil with a Gurney

flap".AIAA Paper: 92–2708. Retrieved 2007-07-07.

18. ̂  Bloy, A.W.; Tsioumanis, N.; Mellor, N.T. (1997). "Enhanced aerofoil performance using small trailing-edge

flaps". Journal of Aircraft(0021-8669) 34 (4): 569–571. doi:10.2514/2.2210. Retrieved 2007-07-07.

19. ̂  Neuhart, Dan H.; Pendergraft, Odis C., Jr (1988-11-01) (PDF).A water tunnel study of Gurney flaps.

NASA Langley Research Center. NASA-TM-4071. Retrieved 2007-07-07.

20. ̂  Giguere, P.; Dumas, G.; Lemay, J. (1997). "T echnical N otes". AIAA Journal 35: 12. Retrieved 2007-07-

07.

21. ^ a b Meyer, R.; Hage, W.; Bechert, D.W. (2006). "Drag Reduction on Gurney Flaps by Three-Dimensional

Modification" (PDF).Journal of Aircraft 43 (1): 132. doi:10.2514/1.14294. Retrieved 2007-07-07. "When hot-

wire anemometry is used, a tonal component in the spectrum of the velocity fluctuations downstream of the

Gurney flap is shown. This points to the existence of a von Kármán vortex street."

22. ^ a b c Prouty, R.W. (2000-03-01). "Aerodynamics   : The Gurney Flap, Part 2" . Rotor & Wing (Access

Intelligence). "One of the critical flight conditions is a high-powered climb. The negative angle of attack of

the horizontal stabilizer can be as high as -25°, whereas in autorotation it may be +15°."

[edit]External links

Wikimedia Commons has

media related to: Gurney flaps

U.S. Patent Re19,412  the original 1935 Zaparka patent