Archives For aeronautical

Every engineer has their own opinion about aircraft design, but there are three important characteristics of an airplane that the end user cares about: 1) Performance, 2) Flying Qualities, and 3) Systems. What makes airplane design difficult is that you cannot change one without changing the others. I’ll illustrate with pictures of the F-35 JSF.

 

Performance
Performance answers questions like: How high, and how fast? For example, how fast can the F-35 accelerate from 0.8M to 1.2M, the critical transonic region? A glance at it’s underside reveals a large cross-section, a weakness that mother nature exploits with wave drag. Initial design called for longer and more slender, but it was too tail heavy.

 

Systems
Systems allow the pilot to use the airplane to get it’s job done. In the case of the F-35, that’s to fly and fight. You can see part of the DAS (distributed aperture system), a collection of sensors, that appears as a bump under the nose of the aircraft below. Systems are needed to get the job done but add drag and take up valuable real estate inside the airplane.

 

Flying Qualities
Understanding how the airplane responds to mother nature’s laws will reveal how it responds when pilots ask it to turn tighter while looking over the shoulder in a dogfight. That’s the objective of flying qualities testing like high alpha and spin testing, as shown here. Pilots want the airplane to be responsive and maneuverable, but that can make it unexpectedly hard to fly in places like high angles of attack.

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Airplanes by Design features photographs of aircraft from a test pilot perspective, highlighting aeronautical engineering characteristics and flight test facts. To see all of the these pictures (and many more of this aircraft and it’s unique design characteristics), click here. You will always be able to access any of these pictures by selecting the Flickr icon in the top menu bar.

Click here to read more about this airplane. 

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Send a message to @FlightTestFact on Twitter to share your Airplanes by Design stories and photos. See more Flight Test photos on Pinterest too.

#Aeroindia starts today — here’s a very brief intro at the flight test sliver of the amazing aerospace industry thriving in India. Check out the aeroindia website too.

This week’s photos take another look at aircraft from the perspective of various engineers introduced last time.

HAL Tejas
The Hindustan Aeronautics Limited (HAL) Tejas is the primary fast jet trainer aircraft at the Aircraft Systems and Testing Establishment, home of the Indian Air Force Test Pilot School.

Aerodynamicists will immediately notice the absence of a horizontal tail surface.

Top view HAL Tejas
A top view of the aircraft reveals a unique delta wing design with two sweep angles. Inlets below the wing will attract the attention of the propulsion engineers. And systems/avionics types will notice many antennae for sensors.

The test pilot school is largely supported by HAL, India’s leading aerospace R&D organization.

To read more about the Indian Air Force check out these links:
1. Interview with an Indian Test Pilot about TPS

2. Overview of the Aircraft Systems and Testing Establishment (ASTE)

3. Wikipedia article

The C-17 has been used extensively during the development of the NASA Orion for airdrop of the Orion CEV Parachute Assembly System (CPAS), a system designed to test the recovery parachutes. Both of these airdrop programs have been completed on the ranges at Edwards AFB, California, and Yuma Proving Ground (YPG) in Arizona.

NASA Orion Drop Test Vehicle being loaded onto a C-17 at YPG Yuma Proving Ground
Here the Orion CPAS test vehicle is rigged on an airdrop platform and loaded into the back of an Edwards AFB, C-17. This photo of the aft end of the C-17 shows the strakes added to the aft empennage during developmental testing to alter airflow and thus prevent the collapse of drogue chutes trailing from the aircraft.

Orion CPAS Airdrop Flight Test extraction
The Orion mated to a rigged airdrop platform just after extraction. Two or three parachutes create drag to pull the platform over rollers on the aircraft’s cargo compartment floor out the cargo door. With careful examination, you can also see the flaps extended for the airdrop. Extension of the flaps serves two purposes: control of the aircraft pitch attitude or deck angle and increased lift at slower speeds.

Orion CPAS Airdrop Flight Test
The first airdrop test of the Orion did not go according to plan. Note the cross-hatched paint scheme used for contrast in high definition, high speed video and photography.

Orion CPAS Airdrop Flight Test Streamer
The recovery chute seen here is in a condition known as a streamer.

NASA photo - Orion airdrop test of parachute recovery system at YPG Yuma Proving Ground
A view from the ground of the Orion CPAS test vehicle separating from its airdrop platform.

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Airplanes by Design features photographs of aircraft from a test pilot perspective, highlighting aeronautical engineering characteristics and flight test facts. To see all of the these pictures (and many more of this aircraft and it’s unique design characteristics), click here. You will always be able to access any of these pictures by selecting the Flickr icon in the top menu bar.

Click here to read more about this airplane.

WANTED: Your pictures and videos.

Send a message to @FlightTestFact on Twitter to share your Airplanes by Design stories and photos. See more Flight Test photos on Pinterest too.