F-35 Lightning II vs Dassault Rafale

[swiss]

The frontal RCS is "usually" (I wouldn't use the word "always" and this chart seems to be a good reason for it) the lowest for aircraft, specially for those where lower RCS was a consideration, yes indeed.

But I couldn't stop myself of being surprised that in the case of the Su-27 - namely the "baseline" Su-27 (the one without RCS reduction measures) - that its frontal RCS is actually not lower than the rest of the aspects except for a very, very narrow spike located at around 45 degrees (2 and 10 o'clock) and like you said, in the side areas at 90 degrees (3 and 9 o'clock respectively).

For the rest of the aircraft aspects, the RCS is basically the same or very similar to the frontal RCS, this again for the "baseline" Su-27. Actually there are parts between 4 and 5 o'clock and between 7 and 8 o'clock (120-150 and 210-240 degrees respectively) where the RCS seems to be considerably lower than the frontal RCS (and thus lower on average than the 20 square meters value). This I believe, can be clearly observed on the chart.

Also note that with the exception of that very, very narrow spike at around 45 degrees that the RCS spikes don't diverge much until they hit the sides areas at around 90 degrees, areas of which are also relatively narrow (more or less 10 degrees wide).

As as such, I'm more than willing to bet that the average all-around RCS of the "baseline Su-27" by taking into account the chart above is indeed those (or around those) 20 square meters. I almost have no doubts about this.
So I still maintain that the Su-27 average RCS (the "baseline one" without the RCS reduction measures) is indeed the 20 square meters that it's also - I grant - very similar to the average RCS of the aircraft's frontal sector.
And again, this was a bit of a surprise to me since I was indeed and initially also expecting a quite lower frontal RCS compared to other angles but this is clearly not the case with the Su-27.

But you see that the spikes around 270° and 90° are a lot thicker than in the front or the rear hemisphere. several times thicker. And up to around 45m2 So they have a lot more impact on the overall RCS. Also from 210 to 150 degrees they are more higher and thicker spikes then in frontal 60°. So i see really no way how the average RCS can be 20m2. Even when the sector between 210 to 240 and 120 to 150 are a bit lower then 20m2. But l have to admit, the difference is lower then I thought.

And it seems the differences for stealth aircraft between the front (+/-30°) RCS and the side RCS is even higher.



So i think the Indian talked about the frontal RCS.

[viper12]

I'd say a simple thing ; check my signature.

Also, the RCS graphs may not be in square meters ; all the diagrams I can recall were in dBsm.

[swiss]

I'd say a simple thing ; check my signature.

True that. We are speculating a lot here.

[ricnunes]

But you see that the spikes around 270° and 90° are a lot thicker than in the front or the rear hemisphere. several times thicker. And up to around 45m2 So they have a lot more impact on the overall RCS. Also from 210 to 150 degrees they are more higher and thicker spikes then in frontal 60°. So i see really no way how the average RCS can be 20m2. Even when the sector between 210 to 240 and 120 to 150 are a bit lower then 20m2. But l have to admit, the difference is lower then I thought.

Yes, indeed you are correct about the spikes around 270° and 90°but again please notice that the (vast?) majority of aircraft seem to exhibit this same behavior regarding RCS spikes.
But again please note that those spikes seems to happen in a quite narrow area of around 10 degrees. Also look at the "improved Su-27" which like you said is probably the Su-35 RCS and while there's a quite big overall improvement (between the Su-27 and the "improved Su-27" or Su-35) which is also noticed on the publicly known RCS values for both the Su-27 and Su-35 that the RCS differences on those 270° and 90°degrees are not that big at all between "both aircraft" (they are actually quite small) which leaves me conclude that those areas/aspects (270° and 90°) don't affect the aircraft's average RCS value that much (probably because they are quite narrow, again around 10º degrees wide).

And it seems the differences for stealth aircraft between the front (+/-30°) RCS and the side RCS is even higher.

Yes I agree and like I previously said I was quite surprised to noticed that the frontal RCS of the Su-27 is not much different from its rear RCS.
But again, I would say (IMO or my 2 cents) that this could be because when the Su-27 was designed that no RCS reduction measures were taken into consideration when the aircraft was designed and all of this assuming that the chart we're talking about is actually accurate.


BTW, nice chart that the posted up there on your last post! To what aircraft does it refer to?

[viper12]

I knew I already saw that aircraft. It's a paper about a long-range interdiction aircraft proposal, the Vendetta, by an undergraduate team, with a 1,750nm radius, all of which must be at Mach 1.6 at or above 50,000ft.

You can get the paper here : https://arc.aiaa.org/doi/abs/10.2514/6.2002-5832

But I'm pretty sure I got my copy of it from some link on the F-16.net forums years ago ; a quick check on the file properties reveals my copy was modified in January 2009...

And like I said, charts like these likely have dBsm values ; for example, the Vendetta RCS figure has rings with negative values, and here's the text next to figure 4.3 :

Figure 18 shows that the vehicle does clearly meet the frontal RCS requirement of 0.05 m2 (-12
dB) set forth in the Request for Proposal.

[ricnunes]

I knew I already saw that aircraft. It's a paper about a long-range interdiction aircraft proposal, the Vendetta, by an undergraduate team, with a 1,750nm radius, all of which must be at Mach 1.6 at or above 50,000ft.

You can get the paper here : https://arc.aiaa.org/doi/abs/10.2514/6.2002-5832

But I'm pretty sure I got my copy of it from some link on the F-16.net forums years ago ; a quick check on the file properties reveals my copy was modified in January 2009...

Thanks Viper for the heads up

And like I said, charts like these likely have dBsm values ; for example, the Vendetta RCS figure has rings with negative values, and here's the text next to figure 4.3 :

That also crossed my mind when first looking at the Su-27 chart since like you correctly said, these charts usually come in dBsm values and not in square meters (or square inches). However after a more detailed look (at the Su-27 chart) I concluded that those values can only be square meters. For example, if you look at the Su-27 chart you'll see that most spikes seem to be around the ring/value 20.
If the value/ring 20 represented 20 dBsm instead of 20 square meters than we would have an average RCS in most aspects (including frontal) for the Su-27 at around 100 (one hundred) square meters! That's too high, even for a Su-27

RCS = 10^(Decibels/10) <=> RCS = 10^(20/10) <=> RCS = 100 square meters

[swiss]

Yes, indeed you are correct about the spikes around 270° and 90°but again please notice that the (vast?) majority of aircraft seem to exhibit this same behavior regarding RCS spikes.
But again please note that those spikes seems to happen in a quite narrow area of around 10 degrees. Also look at the "improved Su-27" which like you said is probably the Su-35 RCS and while there's a quite big overall improvement (between the Su-27 and the "improved Su-27" or Su-35) which is also noticed on the publicly known RCS values for both the Su-27 and Su-35 that the RCS differences on those 270° and 90°degrees are not that big at all between "both aircraft" (they are actually quite small) which leaves me conclude that those areas/aspects (270° and 90°) don't affect the aircraft's average RCS value that much (probably because they are quite narrow, again around 10º degrees wide).




Yes I agree and like I previously said I was quite surprised to noticed that the frontal RCS of the Su-27 is not much different from its rear RCS.
But again, I would say (IMO or my 2 cents) that this could be because when the Su-27 was designed that no RCS reduction measures were taken into consideration when the aircraft was designed and all of this assuming that the chart we're talking about is actually accurate.

I would say we have the same opinion. Except how big the impact of the Side RCS to overall RCS of the Su is.

Thanks also for the link Viper.

When i remember correct dBsm in the "+ area" ist the same as m2?

[ricnunes]

When i remember correct dBsm in the "+ area" ist the same as m2?

No. The only part where dBsm in the "+ area" matches square meters in the value 10 ring.
Look at the formula that I posted above and that I'll also re-post below:
RCS = 10^(Decibels/10)

With this formula you can convert a dBsm (Decibels) value to a square meter value - just replace 'Decibels' within the formula with the desired dBsm value.

As such you can calculate that for example:

0 dBsm = 1 square meter
10 dBsm = 10 square meter
20 dBsm = 100 square meter

[swiss]

When i remember correct dBsm in the "+ area" ist the same as m2?

No. The only part where dBsm in the "+ area" matches square meters in the value 10 ring.
Look at the formula that I posted above and that I'll also re-post below:
RCS = 10^(Decibels/10)

With this formula you can convert a dBsm (Decibels) value to a square meter value - just replace 'Decibels' within the formula with the desired dBsm value.

As such you can calculate that for example:

0 dBsm = 1 square meter
10 dBsm = 10 square meter
20 dBsm = 100 square meter

dB is a unit without dimension expressing the ratio between 2 values (in the same unit)

L(dB) = 10. Log A/B

as an example, A is the incoming power of a radar on a target, B the reemitted power.

If A=10*B, L=3.2 (square root of 10)

Applied to radar equation, it will give you more or less the results shown above.

Ok. Thanks Ric.

[ricnunes]

You're welcome Swiss

[swiss]

https://www.dassault-aviation.com/en/gr ... ified-dga/

On 31 October 2018, the F3-R standard of the Rafale was qualified by the French defense procurement agency (DGA). The development of this new standard, launched at the end of 2013, was successfully completed by Dassault Aviation and its partners in full compliance with contractual performance, schedule and budget.

[swiss]

https://hushkit.net/2018/11/07/top-10-c ... ters-2018/

Dassault’s Rafale is a masterpiece of aeronautical engineering. Despite being burdened with the additional weight of being a carrier fighter, it can mix it with the best fighters in the world (which it has demonstrated on exercises with the F-22 and Typhoon). In performance terms, it is closely matched to the Typhoon, with the French fighter enjoying an advantage at lower altitudes. Few fighters excel at both the fighter and the bomber mission, yet the Rafale is a rare exception. According to one test pilot, the Rafale’s flight control system is unmatched in its responsiveness and precision (and markedly superior to the F-16). This is an important consideration, especially for a carrier fighter. Defended by SPECTRA, which some regard as the best defensive aids suite in the world, guided by one of the world’s most sophisticated radars, and well armed with weapons that include the most advanced aircraft cannon – the Rafale is the hottest naval fighter in the world.

https://www.mbda-systems.com/?action=fo ... t_id=16248

More specifically, the infrared seeker will use a matrix sensor providing greater sensitivity. Meanwhile the radio frequency seeker will use an AESA (Active Electronically Scanned Antenna), enabling smart detection strategies. The reduced volume of electronic components within MICA NG will allow it to carry a larger quantity of propellant, thereby significantly extending the range of the missile. Utilising a new double-pulse rocket motor will also provide additional energy to the missile at the end of its flight to improve manoeuvrability and the ability to intercept targets at long range. Lastly, the addition of internal sensors will allow the monitoring of the status of the weapon throughout its life (including during storage and transport), contributing to significantly reduced maintenance requirements and cost of ownership.

Im really curious if they are plans from mbda to integrate the AESA seeker also in the Meteor. And what kind of advantages gives a matrix sensor for a IR seeker ?

[icemaverick]

That Hush-Kit article states the following about the Super Bug:

It also featured radar cross-section reduction measures that are rumoured to make it the stealthiest fighter (in terms of frontal cross section) this side of the F-22 (though Dassault may dispute this).

Are they really implying that the Super Hornet (and possibly Rafale) are stealthier than the F-35 variants?

[marsavian]

These were claims made around the turn of the century before F-35 was born. Super Hornet and all three Euro-Canards have made this second only to the F-22 in stealth claim during their introductions. They don't make it now.

[swiss]

That Hush-Kit article states the following about the Super Bug:

It also featured radar cross-section reduction measures that are rumoured to make it the stealthiest fighter (in terms of frontal cross section) this side of the F-22 (though Dassault may dispute this).

Are they really implying that the Super Hornet (and possibly Rafale) are stealthier than the F-35 variants?

Maybe they want to say as long the F-35 B/C didn't reach there FOC. This is also the reason why they are not on top of that list.