F-108 Rapier Question

[rickshaw]

OK, let's  make this even better... Always an amazement that the IAI couldn't make a Mirage with a J-79. Avoid too much questions and comments, people are known to have lost their jobs in aviation companies over this particular one. And yes, how come the US couldn't make a Mirage?

Ah, but Boeing did!    

[tahsin]

Ah, yes. But instead of Boeing forced into the fighter market by the Boyd and the like, why not "in the morning"? So that, we could be like "Fairey Delta? Uhmm, yeah..." ?

Nice model as well.

Edit: In case a 5000 words minimum article appears here and positively proves that had nothing to do with the sales prospects of the F-104 and still no response, expect the new Internet laws in Turkey used to good effect. In the sense anything goes and favourite sites failing to appear.

[KJ_Lesnick]

Everybody

Just to be clear, was the F-108 designed

• To fly from CONUS to the North Pole; then back to CONUS?
  
• To fly from CONUS to the North Pole; then land somewhere in the Arctic Circle (Alaska, Greenland)
  
• To fly from Alaska or Thule then to the North Poke, then Back?
  

I'm curious because most sources list it's range as 2,000 to 3,000 miles and to go from CONUS and back would require a range of around 6,300 miles

[rickshaw]

It was, I think you'll find intended to intercept bombers as far north as it could, not necessarily "at the poke[sic]", Kendra/Robynne.   That meant realistically over Canada.

[KJ_Lesnick]

Rickshaw

It was, I think you'll find intended to intercept bombers as far north as it could, not necessarily "at the poke[sic]"

Oh, I thought they wanted the ability to intercept over the pole?

I do remember regardless, proposals for using the F-108 to augment the DEW Line early on.  Did that entail taking off from Thule or Alaska and making one pass over the pole (with several aircraft), or making multiple orbits?

[sferrin]

 However, the F-108 was to be capable of Mach 4 as it was to use the same engines of the F-108 (which were rated for Mach 4), similar construction (of which Walt Spivak, the chief designer stated airframe and inlets were good to Mach 4).

Wut?  The F-108 was a Mach 3 aircraft and used the same engines as the XB-70 (also a Mach 3 aircraft).

[zenrat]

Or you could just go to Wikipedia where it says the combat range of the F108 was 1,271 miles and the ferry range was 2,488 miles.

http://en.wikipedia.org/wiki/North_American_XF-108_Rapier

[KJ_Lesnick]

zenrat

Or you could just go to Wikipedia where it says the combat range of the F108 was 1,271 miles and the ferry range was 2,488 miles.

True, but Wikipedia has not always been the most accurate source.

I'd like to point out the following

• The F-104's listed maximum speed was Mach 2.2: It could probably exceed Mach 3 (for a few minutes at least)
  
• During testing of the XF8U-3, the F-104 and XF8U-3 cruised for protracted periods of time at Mach 2 (probably 30 minutes or more as the F-4 had an intercept radius of 750nm and the F8U-3 could fly as far as the F-4 with a 600 gallon tank or 2 x 370 gallon tanks) with the F-104 having to turn back with the XF8U-3 continuing the next half of the flight subsonic with an F-100 as a chase-plane (Tommy H. Thomason's XF8U-3 book)
  
• The F-104's maximum airspeed was often listed at 710 KIAS: Even pilots who flew it said that they routinely flew above that and saw 750 KIAS a few times, a few pushed it into the low 800 KIAS range and it held together (LTC Walter "BJ" Bjorneby)
  
• The B-58 was originally described as being able to do Mach 2.0 to 2.4 as a dash capability: I suppose you could use the term extended-dash as it relied on continuous afterburner, but it could dash for 60-90 minutes at least if not more than that; admittedly on both Secret Projects and here there have been rumblings to imply it could either approach, equal or exceed Mach 3 for a short period of time at least, and the aircraft was not power-limited with the payloads it carried typically (which was mentioned in a book)
  
• The YF-102 had a maximum speed of 0.98 in level flight, and 1.23 in a dive with the YF-102A was said to be more than twice as fast which would yield a speed of at least 1.96 mach level flight: This was mentioned in a book, and not even a new one -- one from the mid 1970's and back in those days the F-101A was listed as having a top speed of 1.4 or 1.7 when we now know it can do 2.25.  Unless they screwed up, I wouldn't be surprised if 1.96+ would be accurate as it was a streamlined aircraft (good fineness ratio, area-ruled), it had thin delta-wings and internally carried weapons.
  
• The AIM-7's were often listed as having ranges of 20 miles, many could do at least 45 and this was even said on shows like Discovery Wings
  

.
I don't know if this data is classified or anything, if it is, I'll stop asking questions though.

[zenrat]

zenrat

Or you could just go to Wikipedia where it says the combat range of the F108 was 1,271 miles and the ferry range was 2,488 miles.

True, but Wikipedia has not always been the most accurate source.

But it's on the interweb!  It must be true?!

If the data is classified and yet you have found it out then THEY are not doing a very good job.
Have you checked outside for black helicopters?  Any black suburbans with tinted windows cruising past?  Any new to the neighbourhood vans taken to parking in your street?  Any new clicks, pops or crackles on your phone line?  Any unusual delays in downloading web pages or e-mails?  Any PMs from people you don't normally correspond with that have attached photos that could conceal spyware?  Do you seem to constantly see the same cars around you even if you vary your routes?  Has anything inside your house been moved while you are out?  Are you sure?
If you can answer yes to any of the above then you should be worried...

[tahsin]

I don't think there is anybody  in the world that would concur the "improved" performance so far tabulated. Ah yes, there gotta be ways to reduce drag, as the Brits imported some Russians in the 1990s to work on the magic claimed and so forth. If this is a call to learn how; the answer would be no-one knows -if in the very and very unlikely case that it's real- nor would be inclined to tell, especially on a modelling forum... I am pretty sure that you are better than that and it must have been years since you started with the Mach 2.0 F-102...

[KJ_Lesnick]

I got a question: Could a person compute an aircraft's range provided you knew the following parameters of the aircraft's performance

• L/D Ratio
  
• T/W Ratio
  
• Fuel Fraction
  

[martinbayer]

I got a question: Could a person compute an aircraft's range provided you knew the following parameters of the aircraft's performance

• L/D Ratio
  
• T/W Ratio
  
• Fuel Fraction
  

No. Assuming steady cruise flight and using the Breguet Range equation, instead of T/W you need to know the cruise velocity and specific fuel consumption (inverse of specific impulse):

http://virtualskies.arc.nasa.gov/aeronautics/7.html

http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node98.html

http://www.southampton.ac.uk/~jps7/Aircraft%20Design%20Resources/aerodynamics/Breuget%20Equation.htm

Martin

[pyro-manic]

KJ: Why not do an aero-engineering degree? Then you'd be able to work it out yourself....

[KJ_Lesnick]

martinbayer

No. Assuming steady cruise flight and using the Breguet Range equation

Which seems to vary from page to page... I'm unsure which one to use.

Also I have no idea how to determine propulsive efficiency...


Pyro-Manic

KJ: Why not do an aero-engineering degree? Then you'd be able to work it out yourself....

That's not such a crazy idea except that my math skills are pretty rusty and there's probably a slew of courses I'd have to take first

[martinbayer]

martinbayer

No. Assuming steady cruise flight and using the Breguet Range equation

Which seems to vary from page to page... I'm unsure which one to use.

Also I have no idea how to determine propulsive efficiency...

The basic equation does not vary between the different formulations - only the nomenclature that is applied differs somewhat (e.g. use of specific fuel consumption vs. specific impulse, which can for example either be given in seconds or in meters per second and can be converted form one formulation into the other by multiplication with the gravity constant g). But if you can't determine either of these variables, you can't calculate the range.

Martin