Nice one, RAREng.

I hear what you're saying APG63. Unfortunately, it's complete tosh.

The question pertained to the .8 m to 1.2 m acceleration ability of the F-35. Here is a 'chosen for it's simplicity' paragraph. Do try to get through it.

"In aeronautics, transonic refers to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.0, i.e. 965–1,236 km/h (600–768 mph) at sea level. This condition depends not only on the travel speed of the craft, but also on the temperature of the airflow in the vehicle's local environment. It is formally defined as the range of speeds between the critical Mach number, when some parts of the airflow over an air vehicle or airfoil are supersonic, and a higher speed, typically near Mach 1.2, when the vast majority of the airflow is supersonic. Between these speeds some of the airflow is supersonic, but a significant fraction is not."

Embarrassing, I know. But try and cobble up a reply and get back to me.

All my Best!

Channel (or should I say Admin Guru),

Did you really come onto a military aviation website and attempt to explain to us what transonic is, and that speed of sound is linked to temperature?

No one is impressed. Please stop posting these unnecessarily aggressive posts.

Channel 0, notwithstanding the utter bilge you keep spouting, do you seriously expect anyone to take anything you 'cut & paste' seriously given the patronising, arrogant tone of your replies? You do realise a large number of the folks who reply and make valuable and worthwhile contributions to these topics, have actually flown/fly military aircraft or, actually work, or have worked in the aircraft industry?

-RP

I'm terribly sorry, Channel 2. I thought I had been completely clean in my statement. Which part of this didn't you get?

I thank you for your refresher on high performance aerodynamics, which may have been useful had I managed to forget everything I learnt during my 20 years of flying fast jets.

Don't bother trying to include me in your trolling in future.

APG63, I seem to recall you exploring some of the extreme corners of the high speed envelope. The fastest passing VID on record?

My apologies, APG63, if I offended you. It was not my intention.

In my defense, I was taken aback by your statement, which as evidenced by your 20 years of flying fast jets, you obviously didn’t mean, and it’s now clear that you merely misspoke.

Because I’m certain, based on your experience, you would agree that, “Had you bothered to read whatever source you selected for Sears-Haack before copying and pasting it here, you should have seen that it isn't relevant to transonic flight,” is quite literally: the most-wrong statement made on the planet Earth in the last three (3) years.

Because as you obviously know, based on your experience: Sears-Haack shaping makes a radical improvement in the performance of soap box derby cars rolling down a hill at 15-miles per hour. Right? We all know that. All things being equal, a Sears-Haack shaped soap box derby car will win every time over, say, a soap box derby car shaped like a box, or a F-35. (I kid! I kid!) But isn't that right? Human powered cars, salt flat cars, aircraft, submarines, all projectiles: subsonic, transonic, supersonic, being self-propelled or not, ALL benefit from Sears-Haack shaping—regardless of the speed. It’s a pretty fundamental concept. So I know that you merely misspoke or had a brain fart or something.

So please accept my apology, and lets laugh this off.

Based on your experience, you would also know that .8 m to 1.2 m is the ‘transonic’ specification in military programs. Literally. The “.8 m to 1.2 m acceleration spec” is always equivalent to the "transonic acceleration spec.” So yes, perhaps I was a bit defensive, because I didn't know you misspoke or had a brain fart, and again, I apologize.

Below are the original specs.

The baseline transonic acceleration specifications for the three variants prior to the spec change were:

A) A Model: The original “threshold” KPP specification time for transonic acceleration (.8 to 1.2 Mach) was ≤ 55 seconds at 30Kft Altitude. (Add 8 seconds)
B) B Model: The original “threshold” KPP specification time for transonic acceleration (.8 to 1.2 Mach) was ≤ 65 seconds at 30Kft Altitude. (Add 16 seconds)
C) C Model: The original “threshold” KPP specification time for transonic acceleration (.8 to 1.2 Mach) was ≤ 65 seconds at 30Kft Altitude. (Add at least 43 seconds)

This is how it's done...
http://www.ghantafun.com/wp-content/...ut-n-Paste.jpg

Now, can we pleasstay on topic? You know, restarting the F-22 line...

I've just been reading a thread on a different site that had a link to the Wikipedia entry for the B21. Wiki states that the B21 will be a ble to carry a heavy load, it also says that the B21 could be used as an interceptor. If we bear in mind the accuracy of Wikipedia could the B21 be used as a stealthy missileer to act as an F22 force multiplier?

Rand Corporation did a paper in 2010 on the cost to restart the F-22 in the future:

http://www.rand.org/content/dam/rand..._TR831.sum.pdf

It would seem an improvement item for the F-22, if it were to be restarted, is the stealth cladding that has been used. I believe it contributes the most to overall maintenance costs for the aircraft. Perhaps that used on the F-35 would be better.

Channel,


Even when you copy and paste from the internet, you still get it wrong. Your explanations are too simple, and fail to take into account a thorough understanding of the subject.

Im with APG63. I don't think you understand Sears-Haack in relation to transonic and supersonic aircraft.

Wow!!!! You’ve changed your story! First you were arguing about Whitcomb area rule. When that argument fell apart you changed it to Sears-Haack body. FYI, those are two very different subjects, both of which you totally misunderstand. The Sears-Haack body derivation is based on the Prandtl-Glauert equation which is not remotely valid in transonic flow, and area rule applies essentially only in transonic flow. Indeed the Prandtl-Glauert equation contains a singularity! Where? At mach 1 where the flow resistance asymptotically approaches infinity. That was the source of the “sound barrier” term in the late 40’s and why people thought that mach 1 was impenetrable. The Sears Haack body was first derived in 1941, long before the Bell X-1 and long before Whitcomb’s area rule. Or to put it more simply so hopefully even you understand, the two concepts are only superficially related, with area rule applying only in the transonic region of flight, and Sears-Haack appling only in the supersonic region of flight. You mixing and equating these two concepts pretty much confirms what we all suspect: you know how to do google searches and can cut and paste, but you have no idea what it is you are cutting and pasting.


Further, the Sears-Haack body applies ONLY on the limit of a slender, axisymmetric body, like a missile or artillery projectile and is why the V2 had the shape it had. Neither the F-22 nor the F-35 are slender nor axisymmetric. For non-axisymmetric (but still slender) bodies one must use the Robert Jones extension. But again, neither the F-22 nor F-35 are slender, where slender means a fineness ratio of at least 4.5. F-22 has a fineness ratio of about 1.4 and the F-35A about 1.5. To put this in perspective the F-104 fineness ratio=2.5, Concorde=2.4, SR-71=1.9 and V-2=8.5. So none of these aircraft are even candidates for a Prandtl-Glauert, a Sears-Haack or even a Robert Jones body analysis. Only the V-2’s shape and dimensions are applicable. So not only are you barking up the wrong tree, you’re in the wrong forest.

Oh. My. Goodness. A Sears-Haack body is axisymmetric, has a fineness ratio greater than 4.5 and is pointed at both ends. Let's see you use your google skills to find a soap box derby car with that shape. Kids have been doing soap box races since 1914 when Charlie Chaplin popularized it in a movie. They've been using streamlining principles basically from day one. Streamlining (of cars, locomotives, ships, and even soap box and pinewood racers) predates by several decades the Prandtl-Glauert equation and the Sears-Haack body. In case you missed the implication, lets be clear: such streamlining has NOTHING to do with Sears-Haack or area rule. But nice try at obfuscation.

Oh my. Now you've displayed your gross misunderstanding on an entirely different subject. You’ve discovered the fancy term ad hominem, but completely misunderstand its meaning. The folks on this forum have described the contents of your posts here as turds. They have not called you a turd. The latter is ad hominem, the former is not. You on the other hand have called folks "fanboys" as well as hurling multiple personal insults. Look up the term “hypocrisy”. Sadly, it does not apply in your case. Hypocrisy is willful. Your posts indicate you are too ignorant for your actions to be willful. But they certainly are embarrassing, assuming of course embarrassment is even possible for you. That remains doubtful.

Can't help but idly wonder whether one of the more excessive F35 ahem "fans" (jsffan for example) has got bored of incessantly shouting that the F35 is the bestest ever and is now exploring the "it the worstest" angle for their kicks.
There are similarities in the copy and paste posting style...

My understanding is that a lot of the F-35 stealth cladding tech is being applied to F-22 right now. I'm confident that that tech will continue to improve. For example the B-21 program will very likely make strides in that area and I'd venture that at least some of that tech will be incorporated in F-35 as they come off the assembly line, and likely be back fitted to ones already in service.

Further on the subject of an F-22 line re-open: I would think that an F-22N (for "new") would leverage far more than F-35 stealth cladding tech. I would think they would leverage F-35 avionics tech and maybe even engine tech. Both are superior in the F-35 relative to the F-22. And if done right, they could be back fitted to the F-22As and maybe even give the F-22 a much better air-to-ground capability in much the same way that F/A-18 tech applied to the F-15C/D resulted in the F-15E.

KenV,

Recent web posts would seem to indicate a USAF black program for a new interim short-term fighter. The reason being both the USAF and USN both abandoning a longer term fighter replacement with a "family" of drones/links/platforms.

The indications are a choice between a F-22 and F-35 derivative - the decisive factor being a requirement for an open-architecture software system allowing the customer to modify it and add the weapons they like off of it - without the incredibly costly and protracted issues with the current platforms.

With either seeming to cut the throat of the legacy models/manufacturers, I await any developments with interest.....

It's gone awfully quiet in here, has someone changed the Channel?

-RP

ORAC - if they intend to sell them overseas it means the F-35 - as there is no way they're going to allow anyone to access the F-22...................... The Israelis would love to gettheir hands on some F-22's but..............

Just resting my copying and pasting hand. And waiting for the usual suspects to say something F-35 fanboyish, so I can document in the PPRuNe thread archives once again how fanboyishly wrong they are.

Channel 2 is always watching, and waiting...

Channel 2
As you were very positive that your opinions are correct in post #78 are you part of the F35 programme in some way?
I'm only asking as my knowledge of this, and most other programmes has been very limited or incorrect due to me only having access to public/internet info. What I did learn when. I had 'inside' knowledge of various programmes or aircraft was just how wide of the mark public info was, and often even for aircraft that had been in service for a number of years.

As an aside, did I miss your answer as to whether you are or have been a fighter pilot?

Fanboys? Fanboyish? I'm no fan of the F-35. I am however a fan of pointing out absurd claims made by clueless cut and paste artists who equate wave drag and parasitic drag.