Kilocoo316,

1. Your calculations for takeoff distance do not include WIG. Without factoring in WIG, you cannot calculate takeoff distance which is reasonably close t0 the actual distance.

2. The ski ramp is not supposed to induce ‘vertical speed’. The ski ramp changes the angle of attack. This forces greater lift along with the reduced drag due to WIG, which in turn means lower V for VR with a lower drag due to WIG still being a factor till the point the aircraft actually exits the ski ramp.

3. Many other factors (runway friction, air density, air temprature, altitude – actually in this case you should consider ISA sea level standards for density, temprature and altitude,

I used the take-off speed of 140 kts – I really should have used the stall speed but it will do. At take off, the flaps etc will be trimmed accordingly, so the CL eqns drop out, same for ISA effects. Again, Wing In Ground will occur on normal take-off runs, so is cancelled out. At take-off the aircraft is rotated to an angle of attack so again, its out.

I didn’t bother looking at Vr, as rotation is performed by the ski-jump, not the control surfaces of the aircraft. I looked at the point where the aircraft acheived 140 kts (or standard take-off speed), indeed, it should have been stall speed.

Have you the lift curve slope of an Su-33? And the Cd/Cl curves to go along with that? Sure a nice fancy calc to incorporate everything would be nice – but without hard data assumptions must be made. I’m pretty happy with it, if you wanna drop V2 to 130 kts and repeat go ahead.

Contrary to popular belief, I do know a little about what I’m on about 🙂

In 30 and 40 years time DEWs will shoot down F-22s like a marksman shoots down pheasants.

In my opinion:
There is 0 possibility of any more widespread wars between advanced countries, simply because it would go nuclear. Or if there were to be war, it would go nuclear so the F-22 wouldn’t make a difference. See the catch -22 situation in there? 🙂

Yeah, I also had done the calc for 15 deg ski jump not 12 (edited now).

Basically to explain:

Nomenclature:

V0 = The release point speed (i.e. speed of the boat)
V1 = The speed leaving the ski ramp
V2 = The speed at the point where the vertical speed induced by the ski ramp has gone – I decided this had to be the point where the aircraft was at take off speed = 140 kts or 70 m/s

a = acceleration (the controlled variable)
g = acceleration due to gravity (9.81)
s = take off run (fixed variable, 210 and 105m)

V2 = a((V1 Sin(12))/g) + V1

the first component is basically the hang time of the plane after the ski jump times the acceleration of the plane

so:

V1 = V2/(aSin(15)/g +1)

Then using the eqn:

V1^2 = V0^2 +2as

and subbing in for V1

gives

(70^2)/((aSin(15))/g +1)^2 = 15^2 + 2as

iterate it if yez want to 🙂

I used V0 = 15 m/s and V2 = 70 m/s

OK, I’m gonna take account of the ski jump for this one. But to avoid loads of number crunching in the post trust me on this ok [I’ve checked the maths so there shouldnt be a balls up like above 🙂 ].

I’ve guesstimated in take off config that the Su-33 has a lift coefficient of 1.74, (from 140kts and 33,000 kg TOW and wing area of 62 m^2). That will remain constant for the rest of the calc [even if the wing area is wrong it cancels out so dont panic too much about it].

Anyway, working all the crap out (resolving force components blah blah)… basically the aircraft needs to be leaving the ski jump at a forward speed of 65 m/s to take off (well less actually since its still got 1.7 odd seconds of upward vertical velocity due to momentum – so its got that time to get flight speed increased further).

To achieve 65 m/s from the 110 m position needs a T/W of 1.85 – not happening
To acheive 65 m/s from the 205 m position requires a T/W of 1 – again, at MTOW not happening.

BUT

This doesn’t account for the ‘free’ time the aircraft has in the air after take off to get flight speed going. Taking account of it is pretty messy mathematically. Anyway, iterating the expression it chucks out through excel gives.

@ 105 metres a T/W of 1.34 is required

@ 210 metres a T/W of 0.81 is required.

The SU-33 has a T/W of 0.76 ish when fully laden, so no, it won’t quite get off the ground at MTOW, it will be 2.5 tonnes short

Yup, if you’ve too much missiles you’ll have to jettision some to keep T/W up and aero clean as possible when you go to the merge.

…But i still however remain in my position that Su-33 needs TTW ratio better than one to take of from the Ski-jump of kuznetsov, just like the book stated. Have you anything to prove me wrong?

Thats simply incorrect.

You say a T/W of 1, that means the aircraft is accelerating at 9.81 m/s^2.

Neglecting drag, as compared to the thrust of the engines at full afterburner its virtually negligible as such slow speeds:

V^2 = 2*a*s

where;

V = take off speed (well, rotation, which is usually a little more than minimum unstick or stall speed)
a = acceleration
s = take-off run

V is around 140 kts, or 188 km/hr or 52 m/s

a = 9.81 as per your T/W = 1

Giving a take off run of 138 metres.

This is all without a ski-jump (which will shorten the take off run required by a good bit).

Now, the deck length of the kuznetsov is 304 metres…. go figure it out yourself.

High-priority emitters — such as fighter aircraft at close range — can be tracked in real time by the ALR-94. In this mode, called narrowband interleaved search and track (NBILST), the radar is used only to provide precise range and velocity data to set up a missile attack. If a hostile aircraft is injudicious in its use of radar, the ALR-94 may provide nearly all the information necessary to launch an AIM-120 AMRAAM air-to-air missile (AAM) and guide it to impact, making it virtually an anti-radiation AAM.
Of course, there are some targets that do not emit signals. “We prefer it that way, because he’s dumb,” remarked one Boeing engineer. In this case, the F-22 can use its LPI features to track the target — which is not a threat unless another radar is tracking the F-22 and datalinking information to the “quiet” aircraft — and can, if necessary, identify it.

Journal of Electronic defense article
Fighter EW: The Next Generation
by Bill Sweetman
Jul. 1, 2000

Hope that helps yez 🙂