Mach 1.4

Spaceship 2; Ccimage courtesy of irishfireside on flickr

Virgin Galactic is moving ahead with its space program. From AVweb:

“SpaceShipTwo went higher and faster than it’s been before on Friday and Virgin Group President Sir Richard Branson is predicting it will reach space sometime in 2014. Branson had hoped the reusable passenger-carrying rocket would have slipped out of the atmosphere by the end of 2013 but Friday’s flight showed progress toward the ultimate goal. The spacecraft hit Mach 1.4 and 71,000 feet (from a starting atltitude of 46,000) in flight, which was captured from multiple angles by video cameras on the mothership Eve and the spacecraft itself….”

Read the whole story here.

And there are some fantastic images here.

McDonnel Douglas Still Contributing…

The Things with Wings blog highlights the winglets from the MD-12 and how they are being incorporated on the 737MAX:

“First unveiled publically in May 2012, the advanced 737 MAX winglet, which Boeing first described as a ‘dual feather,” was designed to provide up to an additional 1.5% fuel burn improvement on long flights with the promise of even more if a proposed laminar flow surface treatment worked as planned. The MAX wingtip is an all-Boeing design which extends divergently both above and below the wingtip – but its roots go back far further than most know – in fact deep into the company’s Douglas heritage…”

Read the whole post and see the winglets here.

Windowless Cockpits on the Horizon

But what the view? From J. Mac McClellan:

“The benefit would be to save the weight and structural complexity of a windshield. You have to heat a windshield and also make it strong enough to withstand large bird impact at high speed. Windshields also craze, crack and in other ways require replacement.

But the really big savings from a windowless cockpit would be to optimize the shape of the forward fuselage. To be useful a windshield needs to be close to vertical and that distorts the shape of the nose. The abrupt upslope of the windshield forces the airflow to accelerate quickly and that adds drag. At typical jet cruise speeds airflow over the windshield area–called the canopy–is often transonic which is really draggy. Even in slower airplanes the forward fuselage shape is not optimum because of the windshield.”

Read the whole article here.

The Importance of a Trim Tab

Much of the national media – not to mention the aviation media – has been focused on the tragedy at the Reno air races last weekend. The focus of the investigation appears to be around the trim tab and its importance in flight.

J. Mac McClellan does an excellent job of explaining why such a small piece of the airplane matter so much when it comes to stable flight.

“Trim systems are important on any airplane because they are used to neutralize control forces across the airspeed operating range of the airplane. Trim is also used to compensate for forces caused by various CG locations, and to remove control force caused by an out of balance condition such as more fuel in one wing than the other. Extension and retraction of wing flaps also generates pitch force changes in most airplanes.

But pitch trim takes on an even greater importance in a racing airplane because the airplane is flying at the edge of, or more likely beyond, its original design airspeed.”

The entire post is worth a read, you can find it here.

Quick stop in an A380

A380 on approach. ccimage courtesy of abdallahh on flickr

The Smithsonian Air & Space blog has an interesting entry on all of the engineering that took place to ensure the mammoth A380 could stop in an emergency.

“With the Airbus A380 weighing in fully loaded at 1,265,000 pounds, you might think stopping it within a reasonable distance after landing would require a Phalanx of Heavy-duty thrust reversers.

Truth be told, in the megaliner’s braking system, thrust reversers are the least critical components. Airliners are not required to have thrust reversers, and only the two inboard engines on the A380 are equipped with them. The decision not to install reversers on the A380’s two outboard engines saved weight and lowered the chances that those engines, which sometimes hang over runway edges, would be damaged by ingesting foreign objects.”

You can read the entire blog post here.

Empennage: Difference in the Details

The two most popular aircraft in our flight club are a Cessna 172N and a Piper Cherokee 140. There are big differences in these two trainers. The biggest difference, of course, is that the 172 is a high-wing aircraft while the Cherokee relies on a low-wing design.

However, this post is to point out a more subtle difference – the empennage or tail section of the aircraft.

The 172 relies on a fixed horizontal stabilizer and an elevator that connects to that stabilizer. The connection is highlighted below:

credit Pilot's Handbook of Aeronautical Knowledge

The Cherokee relies on stabilator, shown below:

credit Pilot's Handbook of Aeronautical Knowledge

The Pilot’s Handbook of Aeronautical Knowledge describes a stabilator in this way:

“A stabilator is essentially a one-piece horizontal stabilizer that pivots from a central hinge point. When the control column is pulled back, it raises the stabilator’s trailing edge, pulling the airplane’s nose up. Pushing the control column forward lowers the trailing edge of the stabilator and pitches the nose of the airplane down.

Because stabilators pivot around a central hinge point, they are extremely sensitive to control inputs and aerodynamic loads. Antiservo tabs are incorporated on the trailing edge to decrease sensitivity. They deflect in the same direction as the stabilator. This results in an increase in the force required to move the stabilator, thus making it less prone to pilot-induced overcontrolling.”

Next time you are at the hangars, check out the difference.