Wednesday, May 28, 2008

Not Classic Jetliners (5) : Dassault Mercure 100

This series is about jet airliners which failed, either technically or in most cases commercially. With only 12 examples built and 11 sold the French Dassault Mercure 100 was probably the least successful jet airliner of all time. Work began on the Mercure in the late 1960s to produce a competitor to the Boeing 737. The design was similar to the 737 though at 140 passengers capacity was a larger aircraft (the 737-200 being able to carry less than 120).

The Mercure was the first French jet airliner since the successful Caravelle and was designed using Dassault's experience with jet fighters like the Mirage so that it had good high-speed characteristics, indeed was faster than the 737, and had good low-speed lift with it's advanced (for the time) wing. The first Mercure took to the air in 1971.

Unfortunately Dassault could not sell it to anyone, the only order coming from French airline Air Inter. The main reason is thought to have been the poor range of the Mercure compared to it's competitors like the 737 and DC-9. The Mercure was designed for European air routes with a maximum loaded range of 400 miles whereas it's competitors typically had longer range which added to the operational flexibility.

Just 10 production aircraft and 2 prototypes were made, far less than the hundreds originally envisaged. One of the prototypes was later sold to Air Inter. All 11 examples served their airline well, though Air Inter did receive a government subsidy. The Mercure was finally retired in 1995 after 20 years of trouble free service.

Dassault tried to revive the design with versions that had more range, capacity and improved engines but these designs came to naught.

Sunday, May 18, 2008

Geared turbofans

The next big thing in aircraft propulsion is the geared turbofan which should begin to enter service early in the next decade on the new Mitsubishi Regional Jet and Bombardier C Series, but what is it? Flight International explain it well :

A conventional turbofan is divided into high and low pressure spools, each consisting of a compressor and turbine. The low-pressure spool drives the fan and provides most of the propulsive power. The fan works best at slower speeds, while the rest of the spool - the compressors and turbines - are more efficient running at high speeds.
A geared turbofan introduces a reduction gearbox (as you might have guessed) between the fan and the turbine so they both operate at optimum speed.

GTF ground test

Pratt & Whitney's GTF is currently in development and it is hoped to deliver fuel savings of between 10 and 10% as well as cutting noise. The GTF is still ground testing but already has impressed some potential customers and has gained the attention of many airlines around the world.

Saturday, May 17, 2008

Californian smog to be studied by UAVs

Scientists at the Scripps Institution of Oceanography are going to use unmanned aircraft to study Southern Californian air pollution and the region's potential for climate change. The California AUAV Air Pollution Profiling Study (CAPPS) began last month and will gather meteorological data from clouds and the atmosphere over the region until next January. It is thought the region's climate such as it's tendency to trap smog could make the region prone to climate change consequences such as dimming at low levels. Monthly UAV flights will provide data to help evaluate the long-term effects of pollution.

Flights are taking place from Edwards Air Force Base and have to use military airspace because of rules governing the operation of UAVs in civilian airspace.

Tuesday, May 13, 2008

A growing market for efficiency in air travel

The news that Boeing have over 130 orders for an upgrade pack to older versions of their 777 airliner that offers fuel savings of 1% is no surprise given the increases in the price of oil over the last few years and greater competition between carriers. 1% may not seem much but it could save $300,000 per year per aircraft.

Its part of a growing effort to push for greater fuel efficiency of new airliners and improving existing airliners, especially the older aircraft in airline's fleets. American Airlines for example are fitting new tail cones to their McDonnell Douglas MD-80 to reduce fuel use via less drag (and happily thus CO2 emissions). Many efforts to save weight are ongoing, even down to lighter cutlery for the inflight meals.

Its not just the hardware. How airliners fly, and especially land, is also being looked at. ECO-Descend for example allows a pilot to slow down if they are ahead of schedule. Aircraft may also be able to choose their own flight path, a system to allow this is to introduced in Sweden this year.

As oil continues it's rise airlines and airliner manufacturers no doubt will continue their efforts to save fuel. In the next decade we should see the arrival of geared turbofans for example (which i will look at in more detail later).

Wednesday, May 7, 2008

Look what turned up on the beach

Last December the USAF 82nd Aerial Targets Squadron finally phased out the evergreen BQM-34P Firebee target drone, on December the 12th in fact. The Firebee was replaced by the much more advanced BQM-167A Skeeter however things haven't all gone to plan. Last month (yeah i know, come to this blog for the latest news) two Skeeters washed up on the shore near Fort Morgan, Alabama by "spring break revelers". The target drones had been launched in late March and shot down but were not able to be recovered due to the rough sea conditions at the time. They sank and drifted until ending up on the beach, maybe they just wanted to join the party.