History Aspects:
Technical Point of View

Important Outlines

Basic Ideas at the Beginning: Summary ( 02-05-47...02-18-47)

Research from High-Speed Aeronautics, 1955 : Wing Cross Section

Research from High-Speed Aeronautics, 1955 : Arrow Shape (Swept-back wing)

Air-Frame Design: Material Selection

Rear Fuselage Mount vx. Wing-pod Mount ( Advantages/ Disadvantages)

Airframe Division: Summary Report at March 10, 1947

Comparison of Compatitive Aircrafts

Basic Ideas at the Begining: Summary (02/05/47 ... 02/18/47)

02/05/97

Technical experts (Mangaliag, Bryant, Kazunori, Littko) found that

• * Swept wings as currently used--issues of degree of sweep and its relation to lift, wing viability, strength of materials;
• * Centering and possible "shock-absorber" capacity for landing gear as possible solution to wing problems;
• * Engine placement: it is less than clear why Boeing has moved toward pod placement for the B-47. Drag and other issues need to be investigated.
• * Jet airframe shape as a whole is not yet well understood by us. We need "numbers" on these as well as the other airframe issues noted above;
• * Current jet engines are severely limited by materials availability (heat issue);
• * Both of the plausible types of jet engine suffer from severe fuel efficiency problems
• * Takeoff thrust may not be attainable for existing or likely runways under existing CAA regulations, especially in the context of newly arisen public concerns over aircraft noise-related "illness;"
• * Some relief may be obtained via new fuselage materials, compounds or laminates (Mangaliag).
• * Impact absorbing struts as discussed above may assist capturing the cargo market.

02/11/97

Gladys Mangaliag:

Some information concerning military airframe structures during the 1940s and 1950s:

- One of the most common designs consisted of wood framework with a "skin" material stretched over the metal. The other two models at which I looked closely are the Heinkel HE-178 and the Bell P-39. The HE-178 is the world’s first turbojet powered aircraft. It is a single-seat research craft that has a monocoque aluminum fuselage. The P-39 "Aircobra" has a fine streamline and is popular with the Russians. The prototype was built in the U.S. but it is in limited service with the United States Air Force. Perhaps our company can look into this and find some aspects of the design suitable for our passenger jet.

- After talking to NASA aerospace engineer, Lisa Jones, I was able to inquire of some old projects that produced designs that were never really put out into the market. The Lear jet is one that was designed in the 50s, but testing did not really begin until the 1970s. The main aspect of interest here are the landing gears which are designed for energy absorption. The struts are filled with liquid, and as the tires touch the ground, the joints bounce into the next tube and transfers the energy to the liquid. This reduces the impact felt in the fuselage by the passengers. The microfiche I requested from NASA just arrived today. I will take a look at the information and prepare a summary next week. I’m still waiting for a phone call from Tony Maturo at Langley Research Center.

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Research From High-Speed Aeronautics, 1955: Wing Cross Section

Research from High-Speed Aeronautics 1955

Wing Cross Section

The Kutta-Jou-Kowskv theory predicts lar2e values of the lift without accompanying pressure drag in two-dimensional motion. The degree to which this ideal dragless type of flow can actually be approached under suitable conditions is well illustrated by an experiment made by E. N. Jacobs at the MACA's Langley Laboratory a number of years ago. The airfoil in this experiment had a 5-foot chord and extended completely across the (low turbulence) wind tunnel. At an air speed of 50-miles per hour and an angle of attack of 7 degree, a lift force of 100 pounds was measured. The drag amounted to only slightly more than one-third of a pound so that the lift-drag ratio was nearly 300 to 1. For comparison a round rod or wire havin2 the same drag as the lift on airfoil is also shown below.

Figure1 - Airfoil compared with circular wire having equal drag.

The materials is prepared by Kazunori Omori (Technical Expert)

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Research From High-Speed Aeronautaics, 1955: Arrow Shape (Swept-back wing)

Arrow Shape (Swept-back wing)

 

As a flirt her illustration of the relative magnitude of the wave drag for different forms as shown below, according to the indications of our experiments would have the same total drag at a low supersonic Mach number (The comparison made at zero lift).

HIGH-SPEED AERONAUTICS

The materials is prepared by Kazunori Omori (Technical Expert)

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Air Frame Design: Material Selection

Material Selection

Early aircraft construction was wood framing with doped fabric covering. The more popular wood materials were spruce, ash, and poplar. Piano wire was used for truss arrangements and bracing. Later, in the early 20's, the welded steel tube framework, still fabric covered, became the standard for light aircraft engineering. In the mid. 20's, the internally braced monoplane wing was introduced and wood veneer began to replace fabric as a wing covering material. By 1930 many aircraft were using aluminum sheet as a load bearing covering material to give a light structure.

The materials is prepared by Kazunori Omori (Technical Expert)

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Rear Fuselage Mount vx Wing-pod Mount ( Advantages / Disadvantages)

Rear Fuselage Mount vs. Wing-pod Mount

Advantage of Rear Fuselage Mount:

1. Produce a high CL maximum and short take-off
2. Good in control in case of the engine-out
3. Less noise
4. The airplane gross weight penalty is minimized
5. The gross drag penalty is minimized

Counter arguments are:

1. Fixable the smaller yawing moment of an engine out by the smaller tai arm
2. Al jet aircraft can be made sufficiently quiet in the cabin.
3. There is a weight penalty with the rear mounted engine
4. There is a destabilizing inertia effect and positioning payload problem.

Wing Control Surface - Spoilers

1. Could reduce lift force and produce more drag force
2. Produce normal force so that it help the braking system to stop faster

Additional Information:

An underwing podded nacelle with the engine moved forward so that its pressure field did not interfere with the wing's pressure field gave the best solution.

The materials is prepared by Kazunori Omori (Technical Expert)

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AirFrame Division: Summary Report at March 10, 1947

From the first meeting of the board for Curtiss-Wright, the technical team worked to research airframes and possible prototypes that were never released into the market. From the found information the technical team was able to get diagrams of typical transport aircraft that existed during the 1940s and early 1950s. "These families of aircraft, which served on both long-range domestic and international routes, were the Douglas DC-6 and DC-7 series and the Lockheed Constellation series." Both were derived from aircraft developed during World War II.

Moreover, some additional research revealed that two aircraft from the WWII era can be also used as an example. The Heinkel HE-178 is the world’s first turbojet powered aircraft. It utilizes monocoque aluminum fuselage. The other is the Bell P-39 commonly called the "aircobra". It is fine stream-lined and is popular with the Russians. However, the prototype is in limited service with the United States Air Force. This could be one reason why Curtiss-Wright should look at it.

The research concerning fuselages revealed that most passenger transports at that time carried a load of approximately 30-50 passengers. The seats were mostly first-class. From the article, "Airframe Design for Passenger Comfort", combined with the survey conducted by American Airlines, it appears that the important features of the plane should be speed, followed closely by comfort.

Another idea concerns the landing gears. Engineers were experimenting with new designs concerning struts. These are the "legs" which protrude from the bottom of the fuselage as the plane prepares to land. The new design calls for fluid (most likely water) to be put inside the tubes and as the tires make contact with the runway, the joints bounce into each other. This distributes the energy of impact and absorbs it through the liquid, thus reducing the impact felt by the passengers inside the plane. Another application of this is that the luggage will not suffer as much damage as it normally would. This technique may be considered as a "cushion".

Time is another major factor. There is a new chain drive cargo-loading device which cuts down the time it takes to load freight. This reduces ground time for the plane, which then speeds connecting flights. In materials, we found that "Metal-Cals" are being used to cover the surface of the plane. It is made from paper-thin, .003-inch thick aluminum foil. It is almost abrasion proof and has a cellophane-covered "postage-stamp" back which lets the logos be printed. It is very durable and this will help cut down the cost of maintenance since the plane does not have to be painted as often.

Research in metallurgy is also rising. The most efficient and inexpensive material to use is an aluminum alloy with steel. This provides strength as well as light-weight in order to be able to carry a maximum load as well as save on fuel. It can withstand between 180,000 to 200,000 psi.

After deciding on what engine to use, the technical team is currently working on calculations concerning take-off weight, fuel weight, payload weight and empty weight. We are also in the process of finding the aspect ratio as well as the taper ratio. This is going to be accomplished by using spread sheets (Excel). From the presentation in front of Ms. Carroll, we are able to address other issues which concern the entire design of the aircraft. This will be put into effect after the preliminary design is complete.

Materials was submitted by GLADYS MANGALIAG, TECHNICAL TEAM

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Comparison of Compatitive Aircrafts

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Air-IPRO 297-397-497-013: air-ipro@charlie.cns.iit.edu
PAUL BARRETT: barrett@charlie.cns.iit.edu
Copyright © 1997
by Lewis Department of Humanities.
Revised: March 30, 1997.