You might not believe this but books aren’t infalible. In this case your book is wrong.
But I have many of them.
Not according to Tomcat pilots. The TF-30 has a lower bypass ratio than the F110. And it has more power at high speed.
That is impossible according to jet engine theory.
The fact is clear: the more by-pass ratio, the less supersonic thrust.
But it also means more static thrust.
The TF-30 was not designed as a bomber engine. Neither was the F110.
The TF-30 was built for F-111, and the F-110 for B-1A.
Unfortunately for american pilots, they both ended in fighters.
Well of course it’s high, it’s incorrect. One source gave 0.9, everybody else says 0.70-0.73.
See books.
That’s not how it works Firebar and you know it.
That is why variable intakes are built for.
To allow optimised airflow at broad range of speeds.
With fixed intake, the airflow can be optimised only for narrow speed range.
That is a big vice of F-22.
The top speed of various F-16 Blocks actually differ a little.
But i think speed is generally limited by airframe design, even F-16/79 had better supersonic capability but didn’t go faster.
It was much faster.
2,1 against 1,75 Mach.
The F-15A/C didnt see any thrust increase, rather a decline of a few hundred lb to make the engine more reliable.
Eagle, you are right regarding static thrust of F-15A and F-15C.
True, the F-15C ( F-100-PW-220 ) has lower static thrust than F-15A.
But at altitude and in flight, the F-100-PW-220 has significantly higher thrust than older PW-100.
At the same weight and altitude, the F-15C , with PW-220, has higher sustained turn rate than F-15A.
That is a direct influence of lower by-pass ratio.
Intake design plays a large part in an aircraft’s top speed. Getting rid of the variable ramps on the Su-24M, for example, cut it’s VMax down from over Mach 2 to around Mach 1.35.
That is true, but its influence is not so large.
Look at F-104 or BAC Lightning. They both have 2,1 Mach max speed with fixed intakes.
The developement of turbofan engines for fighters had NOTHING to do with the energy crises of the 70s. By then the TF-30 and F100 were ALREADY in service.
Their development started in late sixties which coincides with start of oil crises.
Supposedly the French M53 is has more power at high speed than the original F100 and the TF-30 is better at high speed than the F110 according to a Tomcat pilot.
For the M-53 it it true because of its low by-pass ratio.
As for TF-30 against F-110, both of these have unacceptably high by-pass ratio for a fighter engine, but as the F-110 has far higher static thrust, it has for that percentage higher high-speed thrust, also.
Anyway, both are misserable for a fighter engines.
That is because both are conceived as a bomber engines, and higher by-pass ratio has been retained.
A bad decision.
F100-220 0.6
F100-229 0.35
F100-232 0.34
F110-100 0.85
F110-129 0.77
You forgot to mention figure for original F-100-PW-100 and 200, which have been used in most F-15 and F-16.
It is 0,72.
Also a bad figure. From 1987 it had to be replaced with 0,6 by-pass F-100-PW-220, but many of F-15 and F-16 still have old PW-100 and 200.
Some others.
F101 2
F404 0.34
M53-P2 0.40
TF-30 0.73
F119-100 0.2
F135* (The section was in a post on F-16.net and is not classified- obviously)
Actually, the TF-30 had 0,9 by-pass ratio. A very high figure for a fighter.
Thats because the F-16 intake is designed to work ok up to Mach 1.5 (optimised for subsonic cruise) whereas the F-15 has movable intakes. The F-22 on the other hand has its intakes optimised for 1.5 i.e. supersonic. So you can bet the F-22 has pretty good supersonic acceleration, better than F-15.
It is a big mistake to fix intake to be optimised to 1,5 Mach.
That means that it is not optimised subsonicaly.
One fighter can not fly at only one speed !!
Sure these have influence. But increased thrust and less drag from other areas have influence too.
Wing sweep and span have the greatest influence on drag.
in the 70s the US was forced to the development of high bypass engines due the 70s oil crisis, now they are returning to more closed to TJ coz the engine performance
Of course.
That is a key for americans intention to put higher by-pass engines into a fighters.
But that also produced grevious consequences to higher altitudes performance.
For a modern fighters, more than 0,55 by-pass is considered unacceptable.
While the F101 has a higher bypass ratio than an F110 it is not a “high bypass” engine and it is good for Mach 2.2+ with the right intakes.
For a fighter class engines it is very high by-pass engine.
Speed is important, but not absolut top speed. Even for a classic interceptor (which the F-22 is not), more than M2 is useless.
The F-15 is certainly not the best fighter because it can fly M2.5. That speed is never reached in regular operations.
I said, more than 2 Mach speed means better supersonic acceleration.
That, on the other hand, means less time to some intercepting distance.
The F-15 has 50 % better time to 2 Mach than F-16.
Above 1,5 Mach, the F-16 is straggling for every knot.
How do you know which is draggier. By looks? The wing sweep change from 42 to 48° is not a big thing, and im not sure if the span has been increased.
The span is increased about a half of meter, and sweep is decreased from 48 to 42 degrees.
Both these figures has high influence on drag.
Sorry, these are basics of aerodynamics.
Reg. weight: Read again, thrust/drag is important for speed not thrust/weight. Look at the MiG-25, it can fly M3.
Both of these are important.
As for Mig-25, it has extremely high T/W ratio at supersonic speeds, especially above 2 Mach.
Do not be eluded with its static T/W ratio.
Subsonic flight:
Inlet produces -9 % and + 21% = + 12%
engine = + 82 %
outlet = + 6 %Supersonic flight (Mach 2.2)
Inlet produces – 12 % and + 75 % = + 63 %
engine = + 8 %
outlet = + 29 %
What type of inlet are you reffer to.
You are probably aware that every type has its own figures.
That explains why a Su-24 with fixed inlets stays below Mach 1,5 despite the same TJs,
It is Mach 2,2 aircraft. What do you think the swing wings are for ?
Also, it has turbojets, which means high thrust at supersonic speeds.
The same thing with B-1B and TFs and the B-1A, just to show some examples for better understanding.
For the understanding, its engines are high by-pass turbofans. These engines are not suitable for supersonic speeds.
Compare F-16/79 with F-16A.
In spite of much less static thrust and more that a ton higher empty weight, the F-16/79 had far better supersonic performance.
How far you push an aircraft behind Mach 2 depends on the material for the plane used. because from Mach 2 the heat took its toll from life-time.
For fighters it did not matter through low fuel-load-ratios, when speeds above Mach 2 were reached at heights above 40000 feet briefly.
Not entirely correct. Generally, engines have more limitations than airframes.
Did you know that, for example F-4 K, has airframe limited to 2,3 Mach, but its high by-pass SPEYs engines are limited to 1,8 Mach.