Military Aircraft L/D Ratio Question
 

I'm wondering what the L/D ratios of the following aircraft are, my fascinating largely has to do with the difference between aircraft designed for subsonic flight, and those designed for supersonic speeds.

Any information is appreciated assuming it's not classified

CARGO

C-141A Starlifter

• At the start of the cruise, typical cruise & mach number
• At the middle of the cruise, typical cruise & mach number
• At the end of the cruise, typical cruise & mach number

C-5A Galaxy

• At the start of the cruise, typical cruise & mach number
• At the start of the cruise, typical cruise & mach number
• At the end of the cruise, typical cruise & mach number

FIGHTERS

F-86E Sabre

• At cruise mach-number & altitude: clean
• At cruise mach-number & altitude: -w- drop-tanks

F-101C Voodoo

• At cruise-mach & altitude: clean
• At cruise-mach & altitude: -w- 2 x 450-gallon tanks
• At supersonic/top-speed, high-altitude: clean

F-104C Starfighter

• At subsonic cruise-speed & altitude: clean
• At subsonic cruise-speed & altitude: -w- wingtip-tanks
• At subsonic cruise-speed & altitude: -w- wingtip & underwing tanks
• At Mach 2, high-altitude: clean
• At Mach 2, high-altitude: -w- wingtip-tanks
• At Mach 2, high-altitude: -w- wingtip & underwing tanks

F8U-2/F-8C Crusader

• At cruise mach-number & altitude: clean
• At cruise mach-number & altitude: typical air-to-air load-out.
• At supersonic-speed & altitude: typical air-to-air load-out.

BOMBERS

B-36A Peacemaker

• At typical cruise mach-number & altitude
• At maximum altitude

YB-49

• At typical cruise mach-number & altitude
• At maximum altitude

B-57B Canberra

• At typical cruise mach-number & altitude w/o drop-tanks
• At typical cruise mach-number & altitude -w- drop-tanks

B-58A Hustler

• At takeoff-speed: Fully-fueled w/o external weapons-pod
• At takeoff-speed: Typical operating weight (163,000 pounds)
• At landing-speed and weight: w/o external weapons-pod
• At landing-speed and weight: -w- external weapons-pod
• At subsonic-cruise mach-number & altitude: w/o external weapons-pod
• At subsonic-cruise mach-number & altitude: -w- external weapons-pod
• At supersonic-cruise mach-number & altitude: w/o external weapons-pod
• At supersonic-cruise mach-number & altitude: -w/ external weapons-pod

XB-70A Valkyrie

• At takeoff-speed & weight
• At landing-speed & weight
• At subsonic-cruise mach-number & altitude
• At supersonic-cruise mach-number & altitude

You really come up with some out-there threads Jane. Many of them begin with 'just wondering' or 'just curious' and then ask some very specific questions (or conspiracy theories). I find it hard to believe that anyone could be 'just curious' about the L/D of the F104C at Mach 2, high altitude with underwing and tip tanks etc etc. So what's the deal: are you doing an aero eng degree, do you have aeronautical OCD, are you a message board robot, are you reverse engineering elderly US jets for North Korea? I'm just curious.

Indeed a strange request - with a very long list of aircraft.

My answer is they will all fly like a brick (less than 1:10 I suspect, maybe less than 1:5 in some cases) without the engines.

From Wikipedia about the space shuttle:

"The orbiter's maximum glide ratio/lift-to-drag ratio varies considerably with speed, ranging from 1:1 at hypersonic speeds, 2:1 at supersonic speeds and reaching 4.5:1 at subsonic speeds during approach and landing."

Just above:
Space Shuttle - Wikipedia, the free encyclopedia

Torque Tonight
 

Others think so.

As for me I took 'her' seriously once (a long time ago) and sent 'her' a considered answer as a PM. I got a reply but 'she' clearly had not read what I sent.

I actually look forward to seeing her UAV that she is privately building in the garage.....

A mach-2 flying wing fighter made of balsa wood with underslung podded jets and the ability to carry 200 paratroops and built using 50's tech?

Maybe JD is Gerry Anderson.

Willard Whyte,

Have you nothing better to do with your leave? (p.s. don't forget to turn up a week on Thursday) :E

Check this out - You could do all sorts of experiments in the back garden.:ok:

eBay - The UK's Online Marketplace

Torque Tonight

Well, would you rather say I'm *not* curious; then ask questions? That would sound kind of counterproductive, not to mention completely dishonest.

I remember hearing that the L/D ratio of the F-104 was higher with the tanks on than with them off because it effectively reduced vortex formation. The F-80 Shooting Star also had a similar effect from what I read when it had wing-tanks attached for probably the same reason.

I do actually have OCD. Regardless, I find aviation extremely fascinating, I have since I was about 5 (I traveled a lot). I've pretty much always been fascinated by how things work -- the mechanics behind it, the concepts and so forth.

If I had my way, North Korea would be a glowing crater of glass years ago.


cats five

It does have a very long list of aircraft indeed and I have reasons for all the aircraft that I listed if you are curious.


John Farley

It was actually the first or second message I received. I didn't read it as clearly as I should (I kind of breezed through it) have -- I am sorry about that. Regardless, that doesn't make me a robot (a robot would have read every word), it just means I wasn't paying as much attention as I should have.

And those reasons are ......?

Sounds like someone wanting to fiddle with MS Flight Sim aircraft config editor/designer software. :hmm:

Abbey Road

The cargo-planes and most of the subsonic-bomber planes I listed had to do with the fact that they are aircraft that are designed to fly enormous distances while carrying substantial loads. To be able to do this depends at least partially on highly efficient wing designs which is helped along by the fact that none of these aircraft are designed for supersonic speed.

The B-36A Peacemaker: Was designed for antipodal range, though it didn't achieve it's goal, it still had truly enormous range and a massive payload, which of course was dependent on aerodynamics. This also allowed it to operate well at very high altitudes

The YB-49: It was a flying wing, which is naturally one of the most aerodynamically efficient designs. The fact that it was pretty cool looking is an added bonus.

I did not include the B-47 and B-52 because I already know what their L/D ratio's are.

The C-141A Starlifter: Was the USAF's first purpose-built jet-transport. Could fly large distances while carrying a heavy load

The C-5A Galaxy: Largest transport in US inventory, possesses global range, and the capacity to carry enormous loads owing to it's highly efficient aerodynamics and engines (which is kind of beyond the scope of this particular thread).

I already found out the projected L/D ratio for the B-57 Canberra online, so that isn't necessary now


The F-86E Sabre: It was one of the last fighter design that, while capable of breaking the sound-barrier in a dive, was essentially designed for high-speed subsonic-flight.


Most of the supersonic fighters I listed were based on the fact that they are aircraft that are designed predominantly for subsonic capability, but possess some supersonic capability as well to varying-degrees. My interest largely has to do with basically the effect of supersonic capability on supersonic flight, and the effect of L/D of aircraft when supersonic vs subsonic.

F-101C Voodoo: The aircraft was actually designed to be able to cruise substantial distances while subsonic in order to escort bombers requiring some decent subsonic aerodynamics, and yet be able to fly supersonic as well. On long-range flights, it would be carrying 2 x 450 gallon tanks, on shorter range flights, it wouldn't as I understand it; supersonic flight would probably be impossible with them attached, and the plane would fly clean.

F8U-2/F-8C Crusader: The aircraft had a pretty good range evidently when subsonic (apparently better than the F-100) which necessitates good aerodynamics. The aircraft was used partially as a point-defense interceptor and it could fly fairly far by the standards of fighters when supersonic which would probably partially depend on a good L/D ratio.

F-104C Starfighter: My fascination with this design is that it has thin, razor sharp wings wings that have almost an inverse camber like characteristic about them making them exceptionally efficient when supersonic, while I am pretty sure it would be inevitable that it's L/D ratio would be higher when subsonic, the difference between supersonic and subsonic L/D ratio looks like it could be lower than most aircraft designs. My curiosity regarding wing tanks pertains to the fact that I've been told that the L/D ratio was actually higher when the tip-tanks were attached due to it acting like an end-plate for the wing.


The supersonic bomber designs I listed simply due to the fact that in order to fly for protracted periods while supersonic, one needs even greater aerodynamic efficiency than a plane designed to quickly dash at that speed as there is only so much fuel you can stuff into an aircraft.

The B-58A Hustler: It was the first bomber that was actually designed for protracted supersonic flight. It had very thin, conically cambered delta wings (which improved performance both supersonic and subsonic), large elevons, and the means to shift fuel around as ballast to compensate for the shifting center of pressure allowing the elevon deflections to be minimized. It was a very fascinating design as it was quite small for a contemporary medium-bomber, and seemed more like a large fighter. It had an unconventional weapons configuration, whereas most bombers carry their weapons inside the aircraft; the B-58 carried it's bombs inside a streamlined pod carried outside the aircraft. The aircraft was highly streamlined, and a little bit over area-ruled to compensate for the drag of the pod, though regardless pilots who flew it said that once the pod was off the plane performed better.

The XB-70A Valkyrie: The Valkyrie was the biggest and heaviest aircraft both to fly supersonic, and to be able to fly for protracted periods of time while supersonic. It had an intercontinental range (though less than desired), a large payload, and actually held a record for the highest supersonic L/D ratio for a manned aircraft. I'm simply curious what it is.

I actually do own FSX, but that's not why I'm doing this: If it was, I would have just asked. I'm pretty blunt and I generally say what's on my mind.

Righty ho! :ooh:

Jane, I'm sorry to sound like a killjoy schoolmarm, but you won't gain any real understanding of aeronautics by gathering anecdotes about this and that airplane.

If you really want to understand aircraft design and performance, why don't you read a book about aircraft design and performance?

Maybe

QUEST FOR PERFORMANCE - THE EVOLUTION OF MODERN AIRCRAFT [Paperback]
Laurence K., Jr. Loftin (Author)

Umm, Amazon's price for that book is $116.47. Maybe you can get a look at QUEST FOR PERFORMANCE via interlibrary loan.

Other, more advanced books include

Fundamentals of Aerodynamics (Mcgraw Hill Series in Aeronautical and Aerospace Engineering)
John Anderson (Author)

and

An Introduction to Aircraft Performance (Aiaa Education Series) by Mario Asselin.

The Canonical Works
 

AC Kermode "Flight Without Formulae"

But our interlocuter is clearly not afraid of formulae, so let's step on a bit...

D Stinton "The Design Of The Aeroplane"

To be fair, these will probably put more emphasis on the well-rounded fundamentals than is being looked for, so one more...

K Huenecke "Modern Combat Aircraft Design"

By this time, we should have established a clear understanding that it really isn't about one single performance parameter...

Y

PS. These should be a bit cheaper than the previous suggestions.

Modern Elmo

Even if I bought the book, that will still take time for me to get the book. One of the reasons to ask aviation questions on an aviation forum is that there are people there that can actually answer your questions.


Yanchik

I understand that it doesn't come down to one performance parameter, but that is a parameter that is important.

Jane; "that there are people there that can actually answer your questions." and those that do, rely on you properly reading the answers they give you.

In your opening post you asked 38 questions, almost certainly a record for Pprune, and not one of them has been answered, so maybe doing your own research and taking the offered advice about reading books has merit.

henry crun

Did I phrase my questions wrong?

J-D, as you are in the States, just pick up the bone and ring the Manufacturers,instead of expecting everyone here to do your `wondering` for you. I`m sure it makes us all `wonder` what you are taking in your `Wheaties`. Get down the library,search `Google`,go to the Smithsonian...You are acting like some of the `Yoof` who come on the training websites with ATPL/CPL/PPL questions,and expect everyone to give them all the answers...! after those 38 questions ,you`ll then be `wondering` some more,I`ll bet... If you are a serious researcher,as opposed to a `Walt` then you should know that you`ll gain more satisfactory results if you`ve done it yourself...anyway, most pilots could`nt give a `hoot` about `best L/D ratios...`you jest get it on and go fly...`

she's just a small part of the Chinese information gathering siphon. Same as that supposed blonde who fooled so many people in various other military and closed security forums a year or so ago and then vanished after deleting all her posts when she was "outed"

"Even if I bought the book, that will still take time for me to get the book."

If you had ordered the book(s) the day you asked the question, you would have had them by now as well as having time to read them from cover to cover.

They are all in stock and most are available in NY, you could even walk and pick them up the same day !

.