p 125 6-4, the related text p 126 😉
Balls – I only have jet engine fundamentals to hand.
I’ll have to see about getting MCA Design. 🙂
http://www.amazon.de/Jet-Engines-Fundamentals-Theory-Operation/dp/1853108340/ref=pd_cp_b_1
😉
You have exact page numbers (save me the hassle)?
Not really.
Yes really.
Concorde did not use afterburners to maintain speed.
You can dance as much as you like, but this:
Someone with no idea about the related physics. To get such supersonic range the MiG-31 has to stay above 50 kft at >M 1 (like the former Concorde with minimum burner support) mainly. …
Is completely 100% incorrect.
At supersonic ~ Mach 2,2 the core engine delivers just 8% of the whole thrust. A further 29 % comes frome the nozzles and give an idea about the importance of that for supersonic flight. But the lions-share is from the regulated inlet, which gives a netto gain of 63 %.
At subsonic range it is the other way around. The core engine gives 82%, the nozzles just 6% and the inlet is down to 12% netto.
Out of interest, what is your source for these figures?
The moving deck/buffet is what the damper/FCS is for.
Due to the angle of incidence of the short tail-hook, the window of successful operation will be lower than older hooks, its just dynamics. No amount of playing with dampers can change that, but it can minimise it. The degree of minimisation remains to be ascertained.
The variation in landings from optimum due to the moving deck and turbulence off the stern has to be considered in light of the reduced operating window.
That is why I’m am pointing out “it remains to be seen”.
The hook’s ability to snag the wire when presented is done for the most part.
Apparently, unless the hook is “not in the right place”. 🙂
Recent tests on a piece of static tarmac rather than a moving carrier deck with the associated buffet showed 5 of 8 traps with the 3 missing ones due to the hook not being in the right place.
As I said, the tailhook not being a major issue very much remains to be seen.
The tailhook “not being in the right place” can mean anything, some of which are not good.
It is unfair to compare the F-22, or any other fighter, to the MiG-31.
About the only possible comparison would be the F-14, but even that would still be unfair (fancy landing a foxhound on a carrier deck anyone?).
The MiG-31 is the apex-predator of interceptors. Nothing else in service has ever come close to doing what it does.
[The YF-12 of course is an alternative that was stillborn.]
The tailhook is not a major issue, it was always just a matter of playing around with the hook design and getting the correct damper settings. It is a replaceable disposable item that they could go through numerous design types to get it right
That very much remains to be seen.
5 of 8 traps worked in recent tests and the three missed were due to pilot not placing the hook in the right place.
They only have one wire on the test pad?
If not, prepare for another dismal failure when they try to trap it on an actual carrier.
Those are interesting.
So pitch control becomes the responsibility of the nozzles, freeing up the elevators to act as elevons.
I know that asymmetric nozzle vectoring to augment roll was examined, but due to the close proximity to the aircraft centreline, the effort was not worthwhile.
So what?
That was with some stoneage Simulators systems.. i question the pay back value of such.
Ahhh, don’t get drawn into the fallacy of additional functionality = additional value.
I see on a daily basis people who I consider to be pretty damn bright, completely lose sight of what is important and what is merely an enabler.
I think we can all agree the 3 most important things for a combat pilot are:
– situational awareness.
– situational awareness.
and
– situational awareness.
If the simulators present the information as the aircraft would – then job done.
If the simulators replicate the flight envelope with the same warning characteristics – then job done.
So what if you can’t do A2G, A2A, landing and refuellings in the same mission. Its of secondary concern.
Obviously a valve or gate of some sort would be involved to regulate the temp and not just a simple “always open” solution.
Then you run the risk (in a weapons bay, it wouldn’t be a risk – it would sure as hell be an eventuality) of introducing stagnant pockets of air which quickly become local hotspots.
Its a problem I’m painfully aware of at the moment (not on F-35 before anyone asks) and fixes unfortunately aren’t often clean and simple.
What would probably be needed (for F-35) is a liquid cooling solution; where the components introducing most heat to the bay are glycol cooled with the refrigerant going to a liquid-air heat exchanger which can then be fed via your small duct, with air forced through the HX as it goes down the duct. The valve can then control massflow rate down the duct and it can only go through the HX so no possibility for stagnant zones.
With proper duct design (Meredith effect), drag effects can be zero, if not actually providing thrust at higher machs.
Of course it all adds extra weight, needs electrical power and at low altitude in higher temp climates it may not be that effective without introducing a proper vapour-compression cycle. But that needs even more weight and power.
Urgh.
Aux bay cooling, if needed, could be addressed by adding a LO scoop to the front of each outer bay door with a exhaust vent at the rear of the same door.
The ISA temperature at 40 kft is -56.5 degC.
Its something to bear in mind before considering simple solutions can fix all problems without introducing cascading effects of their own. 🙂
According to studies made on the J-20’s canards, the J-20’s RCS cannot be below 0.001 m^2 on the frontal sector because that’s the RCS contribution of composite radar transparent canards.
Where is this coming from?
The issues should resolve itself over time, as they can now study the aircraft in use rather than take the computer generated guesitimates. So temperature, airflow and cooling can now be measured, and the mods made to the airframe or components to resolve the issue. Thankfully it should be one of those issues that disappears when the design is finalised and in full production.
Agree and disagree.
I know first hand just how hard thermal modelling is – but I also know resolving the issues (without net weight/power increases) can be nigh on impossible.
Yes, no doubt the problems can be fixed, but at what performance cost?