Drag Force and its Coefficient

[gone-ot]

Although actually about aircraft aerodynamics, there's an excellent "shape Cd" table on page 4, and notice the Cd(o) value for the XB-70 "Valkyrie" shown in Table 3.8 on page 45!:

http://faculty.dwc.edu/sadraey/Chapt...oefficient.pdf

[aerohead]

WOW! She's getting printed to take home.And I'll put on a pot of coffee(maybe more than one!) and immerse myself in it.
It's really fun to have numbers to attach to familiar,and 'new' shapes.
!Muchas gracias!

[gone-ot]

• Here is a presentation on wheel-induced drag:

http://www.ltas-aea.ulg.ac.be/cms/up...dynamics04.pdf

• And, here is a college textbook "Solutions Manual" with some VERY useful problems/solutions (especially #11-33):

http://www.iu.hio.no/~ivarj/fluid%20...SM__Chap11.pdf

[aerohead]

You are the font of knowledge today!!!!!!!!!!!!!!!!!
:thumbup :

[freebeard]

Imagine what you could make with the bellytank off a B-58. Too bad they only made 116 of them.

Thanks for the links.

[gone-ot]

Specifications (B-58A) [ source: Wiki ]



Data from Quest for Performance


General characteristics

• Crew: 3: pilot; observer (navigator, radar operator, bombardier); defense system operator (DSO; electronic countermeasures operator and pilot assistant).
• Length: 96 ft 10 in (29.5 m)
• Wingspan: 56 ft 9 in (17.3 m)
• Height: 29 ft 11 in (8.9 m)
• Wing area: 1,542 ft² (143.3 m²)
• Airfoil:NACA 0003.46-64.069 root, NACA 0004.08-63 tip
• Empty weight: 55,560 lb (25,200 kg)
• Loaded weight: 67,871 lb (30,786 kg)
• Max. takeoff weight: 176,890 lb (80,240 kg)
• Powerplant: 4 × General Electric J79-GE-5A turbojet
• Zero-lift drag coefficient: 0.0068
• Drag area: 10.49 ft² (0.97 m²)
• Aspect ratio: 2.09

Zero-lift for XB-70 was Cd(o): 0.0060 and it was a MUCH larger aircraft!

[freebeard]

I take your point. I got distracted by one of the PDFs.

I was thinking of something that would run in the open-wheel Lakester class, with enough room inside for a camper interior.

[mcrews]

Originally Posted by Old Tele man

Specifications (B-58A) [ source: Wiki ]

I built a 1/24 or 1/32 scale model of the XB-70 when I was growing up.
It was about 18 inches long if I remember......

[freebeard]

Here's another thing, from the 2nd PDF...



I finally remembered a search string that found where I had posted this before.



The way I read this is that the low pressure air is that light colored cone behind the axle centerline. The 'Template' line off the top is created by dust carried forward by the tire tread. When it is scoured out by the changing angle of incidence it follows the classic line, it isn't pulled up and forward into the air.

I think this one picture falsifies the pressure normals in the sketch. Probably because of air flows around the sides of the tire as well as over the top. I'd like to see the instrumentation that produced their data.

[gone-ot]

I don't know...but the dust stream coming off the top of the front & rear wheels seems to coincide exactly with the location of the "rotating wheel" (solid-line), ie: where the forward airflow meets & beats-down the pulled-forward air hugging the tire.