Friday, March 28, 2008

Not Classic Jetliners (3) : Boeing 737-100

Wait, isn't this series about jetliners that were a commercial flop? Haven't there been 1000s of 737s built? Indeed the Boeing 737 is the most successful jet airliner to date with well over 5000 built to date but of that only 30 were of the original -100 variant. Design of the 737 began in 1964 with market research showing the need for an airliner that could carry up to 60 people later increased to 100 in consultation with the launch customer Lufthansa. However United Airlines wanted a stretched version which became the 737-200.

Boeing 737-100 prototype - Boeing image

The first 737-100 first took off on April 1967 with delivery to Lufthansa at the end of that year. However Lufthansa remained the only major customer of the type. Everyone else was buying the stretched -200 variant like crazy. Only 30 737-100s were built but over 1000 -200s. Most were to Lufthansa though the prototype was later sold to NASA.

Boeing 737 prototype in NASA service - NASA image

None of the 30 737-100s remain in service, the NASA plane being retired after 30 years of service and is now preserved in Seattle. So why did the 737-100 fail? The difference between the 2 types was not that great, the -200 was just less than 2 metres longer, but the passenger load was higher enough to appeal much more to customers. It was probably the snowball effect in sales and there being no point in Boeing promoting 2 variants that killed off the -100.

New built 737-100s were also ordered by Malaysian Airlines and Avianca though Lufthansa had 22 of the 30. The final -100 in civil service was with Aero Continente in Peru and was retired in 2005. The -100 was involved in 1 accident though there were luckily no fatalities.

Thursday, March 20, 2008

Fairey Queen & Robot Seaplanes

RPVs (Remotely Piloted Vehicles) date back to just a few years after the Wright brothers first took to the air. The brilliant but easily distracted inventor Professor A.M. Low was set the task early in the first world war of producing remotely controlled pilotless aircraft. These were the first guided missiles. Early RPVs were also used as aerial targets.

As the war progressed both the British and Americans developed more RPVs again mostly flying bombs and targets. These did tend to be specially built small aircraft. Control was either using radio or the RPV could have it's flight preset especially in the case of early "aerial torpedos". The launch crew had to estimate the distance to the target and then set the RPV off in the correct direction. Gyroscopes aboard kept the aircraft in the right direction and barometer the altitude. Once the RPV had traveled the correct distance (and so was over the target) the engine stopped and explosive bolts detached the wings so dropping the fuselage and explosives on the target.

However early flying bombs were not very reliable, many veered off course and were never seen again. More luck was had with aerial targets. One of which gave the Royal Navy a wakeup call as to the vulnerability of their ships to aerial attack. In the early 1920s tests led by the American General "Billy" Mitchell had showed that warships could be sunk by bombers. However his tests had been against withdrawn old warships without crews. In response to the tests the Royal Navy said that the bombers had not destroyed crewed warships that could move and shoot back!

An ex-German battleship is hit during Mitchell's anti-ship bombing demonstration in 1921

Therefore to settle the argument the Fairey Queen target drone was created, the first in a long line of full-scale pilotless drone aircraft. The Queen was a modified Fairey IIIF floatplane, a catapult launched aircraft which was used for reconnaissance by the Royal Navy, 3 being converted to Queens. Apart from installing radio gear the Queen also had some aerodynamic modifications to improve stability, however the first couple of pilotless flights came to quick inglorious endings as the drones crashed as soon as they left the catapult launcher on a RN warship (the HMS Valient).

Fairey IIIF floatplane

However once the last remaining Queen could get properly airborne it proved it's use in a test in January 1933. For two hours it flew over RN warships and survived their concentrated firepower! On a later test RN gunners did finally shoot down the Fairey Queen but by then the lesson had (hopefully) been learned! No more Fairey Queens existed but later on in the decade a remote controlled version of the Tiger Moth, the Queen Bee, was built in large numbers and could be seen on many a gunnery range both at sea or over land.

Whether the term "drone" for RPVs came about because of the name "Queen Bee" and it's connection to drone bees is unknown but it is a distinct possibility.

Nowadays there are a few projects to create a drone that can take off and land in water. Warrior Aero-Marine have begun flying their GULL 24 and 36 seaplane UAVs. The GULL 36, which is now the focus of trials, is an 4m wingspan craft has begun trials in the English Channel. The UAV has a new patented stepless seaplane hull which Warrior say improves performance and it helps the plane to handle waves twice as high as conventional seaplanes. The hull is also better at piercing waves allowing for higher taxi speeds and better surface performance.

The GULL series is designed to help users avoid awkwardness of VTOL and ramp launched systems and can be fitted with landing gear for full amphibious operation.

Wednesday, March 5, 2008

UK aerial targets

Aerial Target Systems is the term used in the UK for UAVs and other projectiles used to emulate aerial threats for the testing and training of the various anti-air warfare systems deployed by the the 3 arms of the UK armed forces. Here we will look at the various systems currently used. These systems will be operated by QinetiQ in the Combined Aerial Target Service (CATS) who are to be responsible for all UK aerial target requirements.

BTT-3 Banshee

The Banshee, built by Meggitt Defense Systems, is a piston-engine powered delta winged target that has been in UK service for 20 years and is used by over 40 other countries. The catapult launched Banshee can be remote-controlled in visual range or beyond that by using it's own autopilot with GPS tracking. When they are set to fly autonomously one ground station can operate up to 4 Banshees.

The Banshee can be quickly modified to suit the mission using a variety of plug-in modules including flares, IR sources and a radar altimeter for low-level flight down to as low as 5m.


Falconet, by Flight Refuelling Ltd., and is a fast jet powered target used as the primary trainer for the British Army's Rapier SAMs. The Falconet can be programmed for a variety of attack profiles including low-level and sea-skimming.

Falconet can take off with JATO assistance or more economically from a circular runway. It can carry it's own towed target. It can also be fitted with a variety of equipment including signature enhancers and miss distance indicators.

Mirach 100/5

The Mirach, made by Italian company Finmeccania, is a jet powered subsonic aerial target used by the Royal Navy. It has replaced the Chukar II. The Mirach can be controlled using remote control or fly a pre-programmed flight guided by it's Global Positioning System/Inertial navigation system.

Mirach can be fitted with a variety of equipment including distance indicators, flares and chaff, other smaller drones and interestingly a rearward facing video camera which must have provided a few interesting views of incoming missiles which has included exercises with RN Sea Dart and RAF Sidewinder missiles.