SchorschFixed intakes do not automatically mean “can’t go over Mach 2” as many seem to think.
But it suggests that it would be rather unefficient. However, I once heard that the F-22 has adaptable intakes. But speeds of more than M2 are problematic due to heat problems, most “Mach2-aircraft” hence have restrictions.
SchorschSo why isn’t everybody flying around in subsonic fuel efficient “fighters” with top of the line avionics and stealth? Why make the F-22 supersonic at all let alone being able to cruise there? Why have a minimum manueverability requirement? Why ad cost and weight by building it to withstand 9Gs? Obviously SOMEBODY thinks flight performance matters.
Please stay serious. I didn’t doubt supersonic capability or agility, I just wrote that there is a level, above which an increase in performance does not necessarily mean an increase in overall combat performance. The F-18 is above this level. M1.4 or M1.8 – what does it matter? Both speeds are normally restricted due to fuel consumption (a fighter easily burns one quarter to one half of its fuel when accelerating and holding this speed for less than 5 minutes).
The F-22 is a super fighter with corresponding price tag. It does not offer value for money. Actually the SH is very expensive, too, but I think that is more a problem with US defense procurement, which garantees the wasteful expanditure of billions a year.
With more effort only two things would have been possible for the SH: higher subsonic speed in cruise and potentially a higher dash speed. But imagine how people in the Senat would be bashed if they accepted some billions more to give the fighter-pilots an aircraft that attracts the layman’s community.
SchorschAre you telling us all you don’t understand why flight performance would be useful in an aircraft?
I guess Sens wanted to express that this performance increase does not effect the combat efficteveness, at least not by a wide margin. While avionic systems can sometimes be decisive (HMS, effective ECM, good RWR), performance is not decisive and depends heavily on the tactical situation.
For example:
10% more climb performance means, that your are on altitude in 10% less time, which normally translates to 15 to 20 seconds. Having avionics, that tell you minutes earlier what happens in the air, is a totally different thing. For me as an engineer it is sad to say, but the performance is not that important as long as it is within acceptable boundaries. Hence are most of the dicussions which aircraft is better complete non-sense.
With full weapons load the performance decays rapidly with any fighter. Ask a Tornado Pilot what his aircraft will do when fully loaded. How fast will he be applying max dry thrust?
SchorschWell the Viggen uses a delta-canard layout which is far more advanced than the F-4 (which was designed in the late 50’s). The Gripen also uses the delta-canard configuration so what exactly is its advantage? It’s definitely not the airframe configuration… The only thing I can think of is that the Gripen probably uses more composites in the airframe.
The Gripen is smaller, thus has a smaller engine, it has different wing planform, is a “controlled” aircraft and has a wider range of missions. Don’t know why they build a new one. Bomb-trucking Iraq would be perfectly possible with F-105 Thunderchief, but still the Air Force has F-16 and F-15 for it. Sometimes decisions for new aircraft are not technical.
And: Canards are by itself not an advantage. Ask Kelly Johnson about it.
SchorschSo it is intresting to learn, where that steep transonic drag rise for the SH comes from.
Is it related to later stealth features added? I can not see, that aerodynamic tests were not done before the first flight?!
I think some basic aerodynamic features add that drag:
– low wing sweep
– lots of cross-section area
– not exactly area-ruled
– interference drag as soon as external loads are carried.
But I am not an aerodynamics expert.
SchorschOk, let’s face it: the Hornet still has a transonic drag problem. That is the whole issue. It has sufficient thrust, this high-AOA thing (not that you need it in particular nowadays) and lots of this sweet avionic-thing. But we’re talking about performance.
What is performance? I would say things like:
– top speed
– max cruise speed
– specific range (with weapons)
– acceleration
– cimb performance
– turn rate
– etc pp
Due to its steep transonic drag rise the F-18 has limited performance when it comes to maximum cruise speed. It also prevents it from getting supersonic with any useful weapons load in lower altitudes. At altitude the F-18 (with some AA-weapons) will not accelerate beyond M1.4, whereas a Phantom with small AA-weaopns load still may reach M1.8.
Conclusion:
The Super Hornet can do all the fancy stuff, but it does not prevail in any discipline. It was apparently not designed to be the best performing aircraft ever. I think in terms of military usefulness the SuperHornet does not have any disadvantages. I have never seen any reports about air combat, where the 10% gap in performance made the difference, although it is often quoted because this performance gaps are easier to identify than “soft” defencies (so it is a hobby in my country to relate the loss of the second world war to the inferior climb performance of some Messerschmidt 109 models).
SchorschSEMAE,
We may not be cheap but we do a better job than anyone else.
The problem is that Airbus will have to give more workshare to foreign countries for political reasons. See how the Chinese are blackmailing Airbus. This workshare will always be on the cost of some blue-collar people (and potentially white-collar, too, in the long term) in Europe. The position of the British is definitely weakened, while it is not necessarily eliminated. The British government will surely continue to “pure” money in Airbus. A government can’t afford to lose high-tech jobs.
SchorschSchorsch this is the R-35 specifications chart
Thank you!
This is very helpful data, actually I can interpolate now and gain a useful engine model. The sfc and thrust data is for zero speed and altitude, I guess, but I can use a generic model to get the values for a turbo-jet. For the R-29 or R-27 I will just downsize the thrust levels. I guess the engines are basically similar except for the thrust rating.
Thanks a lot!
SchorschThe F-8 pilots I’ve communicated with who were in squadrons that transitioned to the Phantom said basically the same thing- the F-8 was like a sports car and F-4 was like a truck. The only common gripe the F-8 pilots had against the airplane was trapping aboard the carrier. And this had more to do with the F-8’s being assigned to the smaller 27C carriers.
Just strange that the “truck” is actually faster than the “sports car” and has more excess power at all altitudes and at all speeds. The truck furthermore has more endurance and better armament. In a combat F-8 vs. F-4 the Phantom would have eaten the Crusaders for lunch.
SchorschThe F-106 was a pure interceptor and absolutely unsuitable for tactical strike fighter use. It would have been totally misplaced in the skies over North Vietnam. For that kind of war, the Phantom was the best machine, and actually without it, the USAF would have run in serious problems.
SchorschThe F-8 cannot be fairly compared to the F-4. The Phantom was from a later generation of fighters than the F-8. The closest comparisons to the Crusader would be the J-57 engined Century Series- the F-100, F-101 and F-102. The Crusader outlasted all of the other J-57 engined jets and was a better performer as well.
How about the F-106? And the F-104G? Both flew in the late 80s. The other aircrafts were just outdated as better designs were available (Phantom!).
Vietnam was a bomber/attack pilots war. What replaced the Crusader as a fighter was the F-14.
The Phantom wasn’t used much as bomber by the Navy. A Phantom is not that bad as fighter, even when it comes to dogfight, actually most F-4 got their scores using Sidewinder missile. The advantage of the MiG-21 over the Phantom was small. The MiG-17 often scored due to surprise. In equal combat situations the Vietnamese normally lost.
Schorsch@MiG-23MLD:
Can you give me the exact version of the MiG-23ML-engine and its thrust (dry, afterburner). Possibly you also have specific fuel consumption or pressure ratio.
Thanks.
SchorschI think the document will help you a lot because it also includes some math, not as simple some times but definitively not difficult for engineers.
Actually .., fairly easy. π
And:
A clean F-18C with F404 -GE-400 at 26.000lbs at 4.000ft needs 11 seconds to accelerate from 360 kts to 550 kts, that is 666 km/h to 1020 km/h. Both speeds indicated airspeed.
While the claim that the F-18 is the “draggiest” 4th generation fighter in transonic regime is true. On the other hand, it is quite agile and very versatile. Everything comes with a price-tag.
SchorschHello Schorsch,
the documents/manual MIG-23MLD is talking about is this kind of “aerodynamic manual”. I recommend downloading it. Many values of the graphs are not cyrillic (e.g. Cx or Cy) or easy to distinguish (e.g. ΠΊΠΌ/Ρ is km/h or kmph).
The relation between Cx and Cy depending on mach numbers and wing swept can be seen here. There are a lot of other graphs showing more interesting relations.
Thank you!
I just found these documents when searching through airwar.ru
I am really delighted about the quality of the graphs and actually was able to identify most of the graphs. I gave some to russian-speaking fellows and hopefully will have a useful performance model of the MiG-23, MiG-25 and MiG-29 soon.
SchorschI will try Schorsch as soon as i find the page if it is there i will translate it gladly for you
Is it possible that those kind of data is not in the manual at all? I mean generally there is no data about the aerodynamic characteristics provided in a pilot’s manual, just because the pilot is not in need of that. But I got a very useful reference of ther MiG-29 in the hands. That “Aerodynamic Manual” had these kind of data.
If you find anything that looks like cy over cx, or cx over M, you have a customer here. π
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