Can someone explain this , iam lost

Basically, there’s something called SEP (Specific Excess Power), which is also given by the same equation as climb rate by coincidence:

V*([T-D]/W)

It is basically a measure of the amount of excess power an aircraft has at a given airspeed in level flight per unit weight. It is not an actual rate of climb because:

Actual Rate of Climb = V * sin (alpha)

http://www.dept.aoe.vt.edu/~lutze/AOE3104/climb.pdf

Now if, as in this case V is less than 340m/s (306m/s for M0.9), then actual climb rate can’t be 345m/s because sin (alpha) has a maximum value of 1.0, which would equate to a direct vertical climb. It’s a pseudo approximation of climb potential but since both drag and thrust vary extremely non-linearly between M0.9 and M1.2 (likely optimum climb speed), it is a very poor approximation in this case.

The V*([T-D]/W) is derived by substitution of ([T-D]/W) = sin (alpha) because resolving forces parallel to flight direction gives T = D + W.sin(alpha).

Andraxxus and Peregrinfalcon are trying to pull a fast one. To actually climb at 345m/s, assuming alpha is ~60deg, the aircraft would need to be going ~398m/s or M1.17. Now to climb at that rate, then in level flight at that speed (M1.17), it’s there that the SEP would have to be 345m/s. And we see from the graph, that isn’t the case, it’s about 120m/s at 1km altitude.

Now the Typhoon claims >315m/s, which requires V of 364m/s at 60deg, so it has >315m/s SEP at 364m/s or M1.07, whereas the MiG has about 170m/s. I rest my case.

In summary, two equations must be satisfied to attain that actual climb rate (hdot):

hdot = V*sin(alpha)

AND

V*([T-D]/W) = hdot

OR put another way:

[hdot/sin(alpha)]*([T-D]/W) = hdot = [hdot/sin(alpha)]*[1/sin(alpha)]

since ([T-D]/W) = sin(alpha)

So we actually see from Andraxxus’ graph that whilst the MiG-29 has SEP of 345m/s at M0.9@SL, it can’t actually maintain a climb at that rate.

I have followed this debate over the phone (had to work on the terrain) and wasn’t able to join, but that would make a little difference because Andraxxus is doing excellent job literally destroying you Lukos!

Just a few points.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710017526.pdf

I hope NASA is enough western source for you?

“Nonsteady-state (dynamic) performance test methods were used to determine the
performance of the test airplane. The test data were obtained for level-flight
accelerations and for constant-Mach-number climbs at maximum power and at a
constant heading. The speed and altitude information obtained was used to determine
the total energy of the airplane, which is the sum of the potential and kinetic energy
at a given point in the flight envelope. The rate of change of the total energy per unit
time for the airplane is a measure of the climb potential (specific excess power) of
the vehicle“.

So, even by western standards, climb potential is expressed as specific excess power.

“Climb Potential

The standard-day climb potential (or specific excess power) of the test airplane as
determined from the level-flight acceleration data is presented in figures 9(a) to 9(e)
for altitudes of 10,000 feet (3048 meters) to 50,000 feet (15,240 meters) at 10,000-foot
(3048-meter) intervals, As expected, the variation of climb potential with increasing
Mach number and altitude is similar to the trends of the curves of excess thrust
presented in figure.”

“CONCLUDING REMARKS

The climb-potential (specific excess power) data obtained from the flight tests were
compared with available predicted performance data for the “average” or “typical”
F-104G airplane, It was found that the predicted data did not represent the actual
performance of the test airplane to the degree of accuracy required to compute
meaningful flight trajectories. Therefore, the flight-test excess-thrust and fuel-flow
data obtained were used to define an accurate performance model for the test airplane
for a standard day at maximum afterburner power.”

In essence you base your point on the premises that all you need to determine the planes performance is static T/W ratio and wing loading.
Andraxxus gave the example of Su-27 and F-15 (using official flight manual data) where we can see that such primitive way of analyzing planes performance proved to be false.

Even above presented document shows that the predicted data did not represent the actual performance of the test airplane to the degree of accuracy required to compute meaningful flight trajectories and that the flight-test excess-thrust and fuel-flow data obtained were used to define an accurate performance model for the test airplane for a standard day at maximum afterburner power.

And you have static T/W ratio and wing loading for EF2000 to make a point :rolleyes:

On the other hand Andraxxus presented all the necessary data on RD33 engine dynamic thrust output (thrust dependence on height and speed) and official Mig data on climb rate.

[ATTACH=CONFIG]248704[/ATTACH]

Well, here says it is posible. If you read the text below the chart, it says “climb rate dependence on mach number and height at full afterburner engine setting”.

If you insist on disproving that, someone might consider you to be insane (engineer) person 😉

Cheers!

Nope, they’re are both measuring specific excess power at given air speeds. This is often described as climb potential but it is not actual climb rate. I hope mathematics is a good enough source for you.

Climb rate = V.sin (alpha)

http://www.dept.aoe.vt.edu/~lutze/AOE3104/climb.pdf
http://www.srmuniv.ac.in/sites/default/files/downloads/class12-2012.pdf

If V < 340m/s, Climb rate cannot be >340m/s because sin(alpha) cannot exceed 1.0.

If this is where the MiG-29’s ‘climb rate’ comes from then it is extremely false. Both drag and thrust can and will change non-linearly between M0.9 and M1.2, so SEP at M0.9 at SL != Actual ascent rate capability at SL.

Oh and BTW, your link states that the predicted performance did not match the actual. So what’s the bet that ‘climb potential’ does not match actual ascent rate? Let’s put this another way, if I drop something like a brick from 10km altitude, will all the PE become KE?

sigh… Typhoon was not even mentioned. Most likely this is between the F-16 and the Gripen since the SH is probably too expensive.

If cost had not been an issue they would have ordered 126 Rafale right away….

Finances can change over time.

Some people disagree and claim that there is in fact an option for 18 additional Rafale — not that it really makes that much of a difference, what seems clear is that they will need one additional fighter, since Rafale will not be bought in large numbers. It also seems pretty clear that this additional fighter will not be the Typhoon.

It’s really between the SH, F-16 and Gripen when it comes to future “make in India” programs. Rafale, Typhoon, Mig-35 are all out.

Well we’ll see after the 2021 update but I think the Captor-E gives the Typhoon a significant advantage, especially if Radar 2 is offered. Gripen would not interest India in the same role because it lacks the range and payload capability. SH is a possibility given the significant weapons support and provisions.

It’s pointless to argue with your know-it-all self. The 36 Rafale contract is a bridge to future orders with or without technology transfer. It’s not an MRCA contract

Sure, it could be viewed that way but the contract specifically excludes any obligation for further purchases and stipulates that such purchases can only be as a result of further negotiations IF they happen.

I don’t suppose that an IR missile seeker is any different in this regard. In fact this “IRST” capability is at least 40 years old, not something new.
The new thing that allows for LOAL is the INS, which requires 3D coordinates and not a vague bearing. Whether you like it or not, that’s how the whole thing works.

Nope, it doesn’t. IRST only needs to be pointing in roughly the right direction to detect something. That’s the same whether the system is on an aircraft or a missile head.

Doesn’t have to be a conspiracy theory. You -a systems and military expert- should know that one may cannibalise 3 systems to make one functioning. If the rebels captured more than one BUK they may have used some for spares to get one functioning. Not much of a conspiracy… right?

This just in, lead MH17 investigator calls the act of repair a far-fetched conspiracy theory.:highly_amused:

Who the hell verified that it was non-operational anyway?

Except that the Ukrainian An26 (’19 Blue’) shot down at about 21000-feet on the 14th was probably downed by SA.13 (though strong rumours say it was downed by a Russian fighter using an AAM). Up to and including the 17th there was no credible evidence about an operational Buk (post incident SIGINT analysis and hindsight doesn’t really count).

As noted on numerous occasions the diversion was requested by the pilot. Without the benefit of hindsight, what would have been more negligent, to order a pilot to fly through an identified storm system to avoid an unknown SAM threat or respond to a normal weather routing request? Unknown by all, numerous airliners were in the firing line that day, MH17 just had the misfortune to be the one that was hit.

Blame who you want, but the simple fact remains that the persons responsible for this disaster, are those who deployed the Buk system and fired the missile. The rest is just smoke and mirrors.

One problem with that. An SA-13 can’t reach 21,000ft.

http://rbase.new-factoria.ru/missile/wobb/strela10m/strela10m.shtml#Зенитный

The wreckage also indicated way more than a 5kg warhead.

The Buk comms intercept pre-dated the shoot down, see date. There was also a claim of a captured Buk prior. Plenty of sources were also suggesting a Buk shot down the cargo plane. This is more than enough evidence to stop civil flights over that region.

Why not use a different path around the storm? I.e. fly south of it, or north of the Donbass?

No, it absolutely isn’t smoke and mirrors. A basic route cause analysis shows that the best way of preventing similar disasters in the future is not to fly over war zones, and certainly better communications with both belligerants if they do.

It’s no surprise MH17 got hit and the others didn’t. The others were supposed to be there, MH17 was not, it diverted. This pretty clearly shows the reason why it was targeted beyond all doubt. If there’s one thing you don’t do to someone with a weapon, it’s surprise them. That applies at all levels.