F-14 and F-15 posted Mach speeds

Unread postPosted: 09 Aug 2019, 04:27
by rowbeartoe
HI Everyone.

Why does the F-14 have a claimed top speed of Mach 2.34 and the F-15 Mach 2.5 or in some cases 2.5+? Wouldn't it just make more sense for the F-14 to say Mach 2.3+?
The F-15 has a claimed speed of Mach 1.2 or 1.21 at sea level. Notice it doesn't say Mach 1.2+. Are these speeds at Level flight or on a dive at altitude? Similarly I've seen the F-16 posted as Mach 2+

I've also seen speeds posted in an actual number- F-15 at 1650 mph at above 36,000 feet or 915mph at 1000ft. The F-16 I've seen posted as 1320mph at altitude and 920mph at sea level.

Of interest- I also read the F-14 eventually removed the variable swept intake- giving it a lower top speed?

From what I've read on here, these Jets apparently never reached these top speeds in actual use anyways- but it's still fascinating to market these speeds at altitude and sea level. Why are they sometimes so precise?

Thank you.

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 09 Aug 2019, 06:50
by h-bomb
rowbeartoe wrote:HI Everyone.
Wouldn't it just make more sense for the F-14 to say Mach 2.3+?

Of interest- I also read the F-14 eventually removed the variable swept intake- giving it a lower top speed?

Thank you.


The 2.34 was politics so it was "faster" than the F-4s Mach "2.23". When Hahn converted from the F-4E to the F-16A they took the best engine they could find, and stuffed then in the same airframe. The Wing King and a few others went to the North Sea and tried to reach 2.23, and no one got it. So I take the "Top Speed" of the F-4 and F-14 with a grain of salt.
(Google F-4A and compare the cockpit/nose to the F-4B. Everything from the inlets forward changed. The F-4A set the official top speed)

The F-14 always flew with the external fuel tanks. These are not drop tanks! So the F-14 could not use its theoretical top speed. They were fast enough without the variable intake, and it saved money and man hours. Lots of man hours.

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 09 Aug 2019, 14:46
by sprstdlyscottsmn
I can assure you the F-14 tanks can be dropped.

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 09 Aug 2019, 15:26
by tomcattech
sprstdlyscottsmn wrote:I can assure you the F-14 tanks can be dropped.


Correct

On Tomcat speed:
The F-14A was listed with top speed of 2.34, but actually made 2.41 during flight test (the RIO was tweaking the ramps via special control box in the test article).
A 1.88 limit in the B/D was an artificial one to insure the aircraft would remain stable with an engine out...
Also note that the B/D inlets were rescheduled for optimum transonic performance and the aircraft allegedly were somewhat slower than the A above 1.6.

Glove vanes were fixed in the later airplanes.
They deployed around 1.3 in the A to reduce trim drag by causing the aerodynamic center to move forward, thus improving acceleration.
With the 30% increase of thrust they weren't deemed necessary.

FYI, the F-18E/F, which appears to have a similar inlet, has a fixed one which does limit performance.

On a different note... Pax River had some makeshift tanks with cameras in them to monitor bomb separation during "bombcat" tests.

Image

Image

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 10 Aug 2019, 14:50
by mixelflick
I can't recall where I read this, but supposedly an early F-14 in testing hit mach 2.6.

I found that hard to believe, but the author was pretty adamant. In the real world, I'd say the Eagle and Tomcat were evenly matched in speed, albeit I have heard many an F-15 driver say, "We don't get slow with the gents in F-14's"...

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 10 Aug 2019, 21:43
by sprstdlyscottsmn
mixelflick wrote: "We don't get slow with the gents in F-14's"...

because the F-14 has superior low speed lift capability and a great pilot can point the nose wherever they want... while a nugget will end up only pointing at the ground.

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 11 Aug 2019, 16:00
by f-16adf
That good old quote from that great jet book:

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 12 Aug 2019, 04:54
by sprstdlyscottsmn
I have a copy of that book.

Re: F-14 and F-15 posted Mach speeds

Unread postPosted: 12 Aug 2019, 05:05
by edpop
In one of my F-15 books it said it could exceed Mach 1 going vertical.....................