Putin says new Russian plane better

**highsea** · 30 Jun 10,, 01:34

Originally Posted by andrew

...And the fuselage of the t-50 generates the lifting power. It elongates the range.

Both aircraft utilize lifting body design.

Remember, in aerodynamics, lift= induced drag no matter where it comes from.

Efficiency is drag coefficient. Total surface area counts as much as shape. Skin friction counts as well, and it's affected by every bump and protrusion on the surface. You also have interference drag every where surfaces intersect.

It's not something you can determine by loking at pictures, you have to put them in wind tunnels to find the problem spots.

**andrew** · 30 Jun 10,, 01:46

Yes, I’ve read the wiki article about drag, too, And I am sure the both teams of the designers spent thousands of hours blowing their models in wind tunnels. Nevertheless, they’ve chosen the different designs.

**highsea** · 30 Jun 10,, 01:54

andrew, I am not critical of the design. Sukhoi makes aerodynamic airplanes.

I'm just saying you can't tell drag coefficients from pictures- you can't assume one is more efficient than the other from the features you cited. One has more cross section, the other has more surface area and interference surfaces. Those factors all interact.

**Zinja** · 30 Jun 10,, 08:32

Originally Posted by highsea

^^ Oh, there's a whole lot of things I could say about Putin's remarks, I just don't see the point.

I'll believe it when I see it. To date, Russian engines haven't shown the technical level to obtain the stated performance numbers.

That has been my understanding as well, something doesn't add up.

**TopHatter** · 03 Jul 10,, 01:58

Originally Posted by Zinja

That has been my understanding as well, something doesn't add up.

And it's all a moot point anyway until they actually start serial production and it enters into multi-squadron service with the Russian Air Force.

**Triple C** · 04 Jul 10,, 12:10

Originally Posted by omon

it is ok, no big deal, us still builds better cars than russia,

The Japanese and the Germans might have lost the war, but they still beat all of us on that front.

So far it sounds like the classic Russian v. US aircraft match up. Aerodynamics v. Avionics/Stealth... and no one knows a damn'd thing for sure!

**Jimmy** · 04 Jul 10,, 18:27

Originally Posted by Triple C

The Japanese and the Germans might have lost the war, but they still beat all of us on that front.

That's not nearly as true as it was 15 years ago. VW in particular has fallen off quite a bit.

**biteasaur** · 13 Jul 10,, 16:44

hey there is a buzz going around, russia is only going to order 50 to 100 "t50"s anybody read this yet,something in russian ,which i cant read.cant find the link.anyway they were saying 50 to 100 pak fa backed by however many su35"s they end up with would be enough.i think is how i read it. i know why go to the expense of a decent plane to be built and only build a few/ look what we did with f22.

**Ararat** · 13 Jul 10,, 17:43

Originally Posted by Zinja

Ok, i just made a quick wiki comparison of the two. Generally dimensions wise the PAK is just nominally bigger than the raptor, but what i don't understand is the raptor is heavier by at least a tonne. Does this mean the PAK is of better (more effecient) material?

Secondly, fuel capacity wise, while the PAK figures do not state wherether they include external points, two things are worth mentioning.
i) If PAK fuel capacity quoted is excluding external points, the PAK has significantly more capacity than the raptor, how is that so considering they generally are of the same size? Also wing area wise the raptor is more surface area which i would have thought would neutralise to some extent. Is it because of the PAK's 'tail' tank?
ii) If the figures include external tanks, then the raptor has more fuel capacity than the PAK, in which case how come the raptor has a shorter distance generally in all catergories? Is it just an issue of aerodynamics or is it something else? More effecient engines on the PAK than the raptor?

Normally when they state fuel capacity on the performance charts that figure is without any external tanks.

Size is not a problem.............it all depends of how the fuel system was designed. For example a wing can be completely wet or partially wet depending on design and needs. 2000lbs difference in empty weight is not that significant when it comes to these caliber aircraft.

Which leads me to the third point, the PAK's thrust/weight is significantly better than the raptor, does that mean the PAK has more powerful engines than the raptor? Anyone know the output of the PAK's engines? If the engines are more powerful, assuming bigger size, then how can it go further with gas guzzlers (unless it is the case that PAK engines are 'several' fold better than the raptors')?

Thrust to weight is a ratio so the answer is no, that doesn’t mean at all that the engines are more powerful than another aircraft with lower thrust/weight figures. Since you already stated that the PAK is lighter than the Raptor assuming same power output that would give the PAK a better ratio.
An aircraft that is very light and has a relatively small engine can end up having a higher T/W ratio than a heavy aircraft with a much more powerful and efficient state of the art engine.

What gives the performance is the excess power available beyond what is needed to maintain a stabilized level flight and where does the lift to drag ratio fall at various speeds on that aerodynamic curve when the wing was designed (which also determines stall speed).
As highsea correctly has pointed out every time you generate lift you also generate induced drag in direct proportion which has nothing to do with parasite drag (skin friction) which becomes more pronounced as the airspeed increases.

Finally, the issues of speed (supercruise, max speed) is it just aerodynamics or its something else?

I know wiki has its problems but its a starting point.

Yes, it is aerodynamics with boundary layer control, but you also need that excess power to overcome increased parasite drag….not to mention the new aerodynamic laws that kick in once an airfoil has passed the speed of sound.

Anybody ever heard of a Mach Tuck on a subsonic airfoil?