All posts by Thameem Ansari

AERO-X (hover bike)

                         These hover bikes are now set to become a reality as soon as 2017. Aerofex Corp, a California-based tech company has created a bike that will let enthusiasts speed along at 72kmph while hovering up to 3.6 metres above the ground.

The company claims to be already testing this vehicle, but adds that there’s a lot more room for developments before they let it out for general public. Aero-X could revolutionise the concept of personal flight, and if one sits to fantasise, it’s also the most desired mode of transport right now.

With carbon fibre rotors taking the place of wheels, the Aero-X will be able to take-off and land vertically without the need for a runway or forward speed, according to the company. It’s also reported to be as easy to ride as a motorcycle, as pilots will be able to use the handlebar grips, situated at knee level, to control the hover bike in a similar fashion. They’ll only need about a weekend of training to be able to fly it easily, the company claims.

Running on the automotive gasoline fuel, the Aero-X bike is 4,500mm long, 2,100mm wide and 1,250mm in height. The bike is expected to weigh 365kg. According to the company, the new hover bike can carry two people and can travel for 75 minutes using standard automobile fuel. However, it can’t carry more than 140kg load.

According to Aerofex Corp, the hover bike is designed to bridge the gap between light aircraft and all-terrain vehicles, making it an affordable alternative to planes and helicopters for surveying, search and rescue, border patrol and disaster relief.

The hover bike will offer a variety of safety features such as vertical takeoffs and landings, ducts covering the carbon fibre fans, a roll bar, and optional air bags. The consumer version of Aerofex’s hover bike is expected to be priced at Rs 50 lakh

performence:                                                                          

  • Occupancy: 2 persons
  • Altitude: 0 to 12 feet above surface level
  • Airspeed: 0 to 45 mph (72 kmh)
  • Takeoff Speed: 0 mph
  • Useful Load: 310 lbs (140 kgs)
  • Duration: 1.25 hours

    SPECIFICATIONS

    • Dimensions:
    • Length: 14.8 feet (4.5 m)
    • Width: 6.8 feet (2.1 m)
    • Height: 4.1 feet (1.25 m)
    • Dry weight: 785 lbs (356 kg)
    • Fuel: automotive gasoline

.aero-x-hoverbike-pic-photo-image-22052014-m1_560x420

1_gp-productpage2

source:aerofex.com

Hohmann Trajectories

In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbit of different altitudes, in the same plane.The orbital maneuver to perform the Hohmann transfer uses two engine impulses, one to move a space craft onto the transfer orbit and a second to move off it.This maneuver was named afterWalter Hohmann, the German scientist220px-Hohmann_transfer_orbit.svg

Explanation:

The diagram shows a Hohmann transfer orbit to bring a spacecraft from a lower circular orbit into a higher one. It is one half of an elliptic orbit that touches both the lower circular orbit that one wishes to leave (labeled 1 on diagram) and the higher circular orbit that one wishes to reach (3 on diagram). The transfer (2 on diagram) is initiated by firing the spacecraft’s engine in order to accelerate it so that it will follow the elliptical orbit; this adds energy to the spacecraft’s orbit. When the spacecraft has reached its destination orbit, its orbital speed (and hence its orbital energy) must be increased again in order to change the elliptic orbit to the larger circular one.

Due to the reversibility orbits, Hohmann transfer orbits also work to bring a spacecraft from a higher orbit into a lower one; in this case, the spacecraft’s engine is fired in the opposite direction to its current path, slowing the spacecraft and causing it to drop into the lower-energy elliptical transfer orbit. The engine is then fired again at the lower distance to slow the spacecraft into the lower circular orbit.

The Hohmann transfer orbit is based on two instantaneous velocity changes. Extra fuel is required to compensate for the fact that the bursts take time; this is minimized by using high thrust engines to minimize the duration of the bursts. Low thrust engines can perform an approximation of a Hohmann transfer orbit, by creating a gradual enlargement of the initial circular orbit through carefully timed engine firings. This requires a change in velocity (delta-v) that is up to 141% greater than the two impulse transfer orbit (see also below), and takes longer to complete.

 img.source;wikipedia

[GARD]

Advanced Medium Combat Aircraft (AMCA)

The Advanced Medium Combat Aircraft (AMCA), formerly known as the Medium Combat Aircraft (MCA), is a single-seat, twin-engine fifth-generation[2] stealth multirole fighter being developed by India. It will complement the HAL Tejas, the Sukhoi/HAL FGFA, the Sukhoi Su-30MKI and the Dassault Rafale. In February 2013, the Aeronautical Development Agency (ADA) unveiled a 1:8 scale model at Aero India 2013.
Funding and future developments:
In November, 2010, the Aeronautical Development Agency (ADA) sought $2-billion (approximately INR 9,060 crore) of funding for the development of the advanced medium combat aircraft (AMCA). PS Subramanyam subsequently stated, “We have just started working on this fifth-generation aircraft, for which we had already received sanctions to the tune of Rs 100 crore. The way the government is cooperating, I am able to say that we will receive the funding ($2 billion) in the next 18 months.” Funding will initially be utilized to develop two technology demonstrators and seven prototypes. The first flight test was expected to take place by 2017. Currently, the configuration finalization is planned for 2018, with the first flight planned for 2020.
By August 2011, the aircraft was in preliminary design phase. As of July 2012, with aerodynamic design optimisation near complete, the AMCA’s broad specifications are final. The aircraft will have a weight of 16-18 tonnes with 2-tonnes of internal weapons and four-tonnes of internal fuel with a combat ceiling of 15-km, max speed of 1.8-Mach at 11-km. The final design is expected to be shown to the air force by 2012, after which full scale development on the aircraft may start. In February 2013, the Aeronautical Development Agency (ADA) unveiled a 1:8 scale model at Aero India 2013.
Design:
The AMCA will be designed with a very small radar cross-section and will also feature serpentine shaped air-intakes, internal weapons and the use of composites and other materials.
As part of the multidisciplinary design optimisation (MDO) currently on for the AMCA—wind-tunnel testing model of the MCA airframe was seen at Aero-India 2009. —that design-based stealth features will include further optimised airframe shaping, edge matching, body conforming antennae and a low IR signature through nozzle design, engine bay cooling and work on reduced exhaust temperature. The aircraft will have an internal weapons bay and radar-absorbent paint and composites.
As well as advanced sensors the aircraft will be equipped with missiles like DRDO Astra and other advanced missiles, stand-off weapons and precision weapons. The aircraft will have the capability to deploy Precision Guided Munitions
General characteristics:

  • Crew: 1 (pilot)
  • Length: 16.5m (Approx.) ()
  • Wingspan: 10.9m (Approx.) ()
  • Height: 5m+ ()
  • Empty weight: N/A ()
  • Powerplant: 2 × GTRE GTX 35 VS Kaveri NG turbofans
  • Dry thrust: 54 kN (12,130 lbf) each
  • Thrust with afterburner: 90 kN (20,230 lbf) each

Performance:

  • Maximum speed: Mach 1.8+
  • Range: 1000 km + ()
  • Service ceiling: 15,000+ ()
  • Rate of climb: N/A ()

amca

 

img.source:www.barat-rakshak.com

Nikolaus Otto’s four stroke engine process

Nikolaus Otto was born in Holzhausen, Germany on 10th June 1832. In his early years he began experimenting with gas engines and completed his first atmospheric engine in 1867. In 1872 he joined with Gottlieb Daimler and Wilhelm Maybach and in 1876 developed the first 4-stroke cycle internal combustion engine based on principles patented in 1862 by Alphonse Beau de Rochas. Although Otto’s patent claim for the’Otto Cycle’ was invalidated in 1886, his engineering work led to the first practical use of the 4stroke cycle which was to provide the driving force for transportation for over a century. Nikolaus Otto died on 26th January 1891.

image

Induction Stroke
The induction stroke is generally considered to be the first stroke of the Otto 4-Stroke Cycle. At this point in the cycle, the inlet valve is open and the exhaust valve is closed. As the piston travels down the cylinder, a new charge of fuel/air mixture is drawn through the inlet port into the cylinder. The adjacent figure shows the engine crankshaft rotating in a clockwise direction. Fuel is injected through a sequentially controlled port injector just behind the inlet valve.
From a theoretical perspective, each of the strokes in the cycle complete at Top DeadCentre (TDC) or Bottom Dead Centre (BDC), but
in practicality, in order to overcome mechanical valve delays and the inertia of the new fuel/air
mixture, and to take advantage of the momentum of the exhaust gases, each of the strokes invariably begin and end outside the 0,180, 360, 540 and 720 (0) degree crank positions
see the Otto valve timing chart

image

image

Compression Stroke
The compression stroke begins as the inlet valve closes and the piston is driven upwards in the
cylinder bore by the momentum of the crankshaft and flywheel.
Compression in a spark ignition engine is used to force the oxygen and hydrocarbon molecules of the fuel/air mixture into close proximity with each other. This not only raises the temperature
significantly (the work of compression is converted into heat), but the action transforms
the mixture from something that is extremely difficult to ignite under normal atmospheric conditions into something that will burn rapidly after being ignited with just a spark Unfortunately, with lower (unleaded) octane fuels and high compression ratios, it is possible
to generate sufficient heat during compression for the mixture to auto-ignite, thereby effectively limiting the practical volumetric
efficiency of the Otto cycle.

image

Spark Ignition
Spark ignition is the point at which the spark is generated at the sparking plug and is an essential difference between the Otto and Diesel cycles. It may also be considered as the beginning of the power stroke. It is shown here
to illustrate that due to flame propagation delays, spark ignition timing commonly takes place 10 degress before TDC during idle and will advance to some 30 or so degrees under normal running conditions.

image

Power Stroke
The power stroke begins as the fuel/air mixture is ignited by the spark. The rapidly burning mixture attempting to expand within the cylinder walls, generates a high pressure which
forces the piston down the cylinder bore. The linear motion of the piston is converted into
rotary motion through the crankshaft. The rotational energy is imparted as momentum to the flywheel which not only provides power for the end use, but also overcomes the work of compression and mechanical losses incurred in the cycle (valve opening and closing, alternator,
fuel pump, water pump, etc.).

image

Exhaust Stroke
The exhaust stroke is as critical to the smooth and efficient operation of the engine as that of
induction. As the name suggests, it’s the stroke during which the gases formed during combustion are ejected from the cylinder. This
needs to be as complete a process as possible, as any remaining gases displace an equivalent
volume of the new charge of fuel/air mixture and leads to a reduction in the maximum
possible power.Tuned exhaust manifolds help to maintain the
momentum of the gas during the stroke to assist in the removal of the exhaust gases. They can
also be tuned within the maximum power rev range to create reflections or standing waves at the exhaust port to prevent some of the new fuel/air mixture from disappearing through the exhaust port during valve overlap (see below).

image

Exhaust and Inlet Valve Overlap
Exhaust and inlet valve overlap is the transition between the exhaust and inlet strokes and is a
practical necessity for the efficient running of any internal combustion engine. Given the
constraints imposed by the operation of mechanical valves and the inertia of the air in the inlet manifold, it is necessary to begin opening the inlet valve before the piston reaches
Top Dead Centre (TDC) on the exhaust stroke. Likewise, in order to effectively remove all of the combustion gases, the exhaust valve remains open until after TDC. Thus, there is a point in each full cycle when both exhaust and
inlet valves are open. The number of degrees over which this occurs and the proportional split across TDC is very much dependent on the engine design and the speed at which it operates.

image

source:www.kruse-ltc.com