More New Aerodynamics

[1964-M20E]

Just to note it appears that the rotors on the mars helicopter resemble the Prandtl propeller design.  Wide root and very narrow tip for high speed operation and Mars DA is pretty high compared to earth.

[Hank]

On 4/21/2021 at 12:09 AM, carusoam said:

4) Interesting materials being used lately.... Lots of aluminum being intricately formed for large Sport Ute parts... like Ford’s expedition (hood and tailgate) and the F150 got an aluminum bed....

The F150 went all aluminum, including an extruded frame, several years ago. I went to look at one, they had a frame section cutaway at the dealer. Either 2014 or 2015 (calendar year).

Based on my Mooney experience, I decided having an all aluminum vehicle for daily use would not be pleasant. I explained that to the salesman as I got back into my steel Ford Ranger and drove away . . . . One aluminum machine is plenty!

[A64Pilot]

Interesting why would you think aluminum framed would be bad?

Aluminum bed is a joke for a work truck, but very few new luxury trucks are ever worked, they are just passenger vehicles, but toss bricks into an aluminum bed and it will be damaged, maybe even holed.

‘Many years ago club car golf carts went with an aluminum frame and many consider to be far superior to steel as golf courses are often fertilized and that rusts out steel. but has little effect on aluminum.

‘Aluminum framed bicycles are known to give a “harsh” ride, but are relatively lightweight.

[Hank]

@A64Pilot, wash your new aluminum vehicle with Simple Green every week for a year. Then ask again why I think one aluminum vehicle (my Mooney) is enough. Or try to remove a shopping cart dent from your aluminum door.

[cliffy]

2 hours ago, Hank said:

@A64Pilot, wash your new aluminum vehicle with Simple Green every week for a year. Then ask again why I think one aluminum vehicle (my Mooney) is enough. Or try to remove a shopping cart dent from your aluminum door.

Using a magnet and a small steel ball might just roll out that dent easier than on a steel door.

[Hank]

23 minutes ago, cliffy said:

Using a magnet and a small steel ball might just roll out that dent easier than on a steel door.

Aluminum stretches when it bends. It will roll out, but not smoothly. 

[Blue on Top]

On 4/20/2021 at 6:17 PM, EricJ said:

Unless you count airliners and military aircraft, then they're all over the place and have been for a long time.   Fiberglass was pretty much developed for airborne radomes in WWII.

There are small parts of airplanes that are composite, but only for special purposes.  The 787, which is composite structure, is composite due to less corrosion issues not it's strength to weight ratio (which is less than aluminum).  Even when aluminum mesh is used for lightning strike, the part is heavier because a layer of fiberglass has to be added to the layup so that the carbon doesn't corrode the aluminum.  A Boeing engine cowling/pylon is a great example.

[EricJ]

6 minutes ago, Blue on Top said:

There are small parts of airplanes that are composite, but only for special purposes.  The 787, which is composite structure, is composite due to less corrosion issues not it's strength to weight ratio (which is less than aluminum).  Even when aluminum mesh is used for lightning strike, the part is heavier because a layer of fiberglass has to be added to the layup so that the carbon doesn't corrode the aluminum.  A Boeing engine cowling/pylon is a great example.

I don't call 777 wings and rudders "small", but that's probably relative.   The 777 has had a lot of composite parts from the beginning.  Airbus has been even more aggressive with it, with the A350 having a lot of large composite piece, apparently more than 50% of the structure.  The A380 as well and the A400 was mostly composite.

The Spruce Goose was designed in the early 1940s and was made with plywood Duramold composite.  DeHavilland pioneered plywood composite aircraft construction starting in the early 1930s up through the Mosquito in WWII.  The T-39 we had in our hangar in A&P school had some composite control surfaces, with honeycomb with aluminum skin.   It was built in the early 1960s.   Significant pieces of the SR-71 were polymer composites.  My understanding was that many military aircraft at that time used many honeycomb composite structures with aluminum or titanium skin.

Regardless of the engineering reasons for using various composite materials, they've been out there for a long, long time and are being used more now and on bigger structures than before.   There are tradeoffs with everything, but composites have had a place in aircraft construction for a long time and it appears to still be growing for both large and small aircraft.  I think composite airplanes have been around all over the place for nearly a hundred years.   I think aluminum or similar construction airplanes are going to be around for a long time, too.

 

 

[Hank]

The first Wright Flyer was composite--bamboo frame and fabric. 

[Blue on Top]

The best material should be used in all cases, and best is relative.  If cost and strength to weight ratio are key requirements, aluminum is best.  If corrosion resistance and highly contoured surfaces are key, composites often win.  It's all relative. 

[Blue on Top]

3 minutes ago, Hank said:

The first Wright Flyer was composite--bamboo frame and fabric. 

Not sure about bamboo, but definitely untreated fabric ... at 45 degrees (to allow the surfaces to warp).