HAL Tejas

Originally posted by Darkpr0
..The problem with it is that it's likely unable to keep up its speed while its turning in WVR...

And so what does that mean?
For starters, it means that the turning radius will be much shorter.
Its T/W ratio is greater than 1(~1.1).
I'm unsure of its T/W with the Kaveri engine but it will be greater than the above I believe.
The t/w ratio of the Gripen is

is it me or is there an influence of the folland gnat in the design?

Harlequin,

Yes I do see some resemblance, but I can't pinpoint it!
Waynos?

If the LCA performs anything like the Gnat did in IAF then we have a winner for sure!


Ironically the Gnat's success in the war it operated was due to its small size and close ACM abilities. Moreover, all the Gnat's a2a kills in the IAF were F-86 Sabres, the then reputed dogfight maestros.

Darkpro,

Upon closer evaluation, it seems that the LCA does indeed have a high
wing area to total surface area ratio(35%) whereas other delta designs like the Gripen(22%), Rafale(27%), Typhoon(29%) and J-10(25%).
Also most the aircraft mentioned in comparision here have T/W ratios greater than 1.1 as opposed to the 1.1 T/W ratio of the LCA(with the FE-404 I believe). The exceptions are the Gripen and J-10.

But what I do believe is that the the forward canards and/or tailplanes are not taken into consideration while logging wing area for these planes.
Now I'm not exactly sure of this but this is IMO.

The Mirage 2000 on the other hand has a wing area to total surface area ratio of 31% with a

I've been staring at LCA and Gnat pics for the last 5 minutes and I believe the resemblance is in the frontal fuselage area and the air intakes.
Moreso the relative positioning of the intakes on the frontal fuselage.

What say?

when looking at teh front the first thing that sprang to mind was the Gnat - yes 1 is a delta and teh other isn`t - but that 3 quater view , screamed Gnat to me , front fuselage and the realtive position of the intakes.

Originally posted by Daedalus3
But what I do believe is that the the forward canards and/or tailplanes are not taken into consideration while logging wing area for these planes.
Now I'm not exactly sure of this but this is IMO.

Very possible indeed. It wouldn't surprise me if the tailplane area was omitted, but the issue still remains. That is a massive wing for the size of the a/c. The thrust may not be enough to keep up the energy in high-G turns if a dogfight scenario should arise.

I can see an overall similarity, especially in the way they are both lightweight agile fighters, but of course there is no actual relationship between the Tejas and the Gnat (or indeed anything else).

Regarding agility, I did read once that the reduced sweep forward root of the Tejas wing acts in the same way as the F-18/Su-27 LERX and similarly to a canard in enhancing the planes instantaneous turn rate, which is clever and simple if it is the case.

reply to post by Darkpr0


Arhha....... now I see what you mean, sorry for my bluntness.

As we have known that, the more speed close to sonic, the more effect wave drag caused than friction drag. So there is nothing to do with wing area concerning the high speed maneuver.

Except F-22 and Eurofighter, I believe there is no jetfighter could do functional supersonice maneuver, but high speed maneuver which means capability of pass in or out sonic, is still important even more than subsonic maneuver. So delta wing that lead to less transonic drag is better than normal wing resemble to FC-1 or Hornet.

Then the intake, now we focused on, is being a key trouble, that consequentially is a diathesis which cause the high speed capability of Tejas was reduced.

reply to post by emile


Quite true..

As it was observed in the F-16XL:

These changes resulted in a 25% improvement in maximum lift-to-drag ratio in supersonic flight and 11% in subsonic flight, and a plane that reportedly handled much smoother at high speeds and low altitudes. The enlargements increased fuel capacity by 82%. The F-16XL could carry twice the ordnance of the F-16 and deliver it 40% further. The enlarged wing allowed a total of 27 hardpoints on the plane
Wiki Source

Notably the Wing Surface Area to Total Surface Area in the F-16XL is 34%.
Very close to the 35% of the LCA.

I knew there was something a little familiar about the Tejas layout however, I think this is what I was thinking of. I am sure HAL took nothing from this (even if they did know it existed) but who else has designed a shoulder mounted tailless delta fighter apart from HAL and De Havilland?

The reason i thought Gnat was really the shape of the front - it screamed Gnat to me anyway - not that the 2 really have much in common

reply to post by waynos


I'm sure you remember this one

reply to post by emile


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Originally posted by emile
As we have known that, the more speed close to sonic, the more effect wave drag caused than friction drag. So there is nothing to do with wing area concerning the high speed maneuver.

True, but that wasn't quite was I was going for.

The idea is that in a WVR combat (be it with guns or missiles, I don't care) there's bound to be some very tight turns. Now while I've no doubt that this thing is incredibly zappy, the thing that makes me wonder is that the wing is so huge. As your speed decreases throughout the turn, I think the aircraft skids more and more (changing attitude while direction is still a few degrees behind). As this happens, more of the wing is exposed to airflow, and on a wing that size it's bound to be a lot of drag. That's the point I was trying to get across, sorry if it wasn't clear.

Originally posted by Harlequin
reply to post by emile

 

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Ditto on that!!

I think its the Avro Arrow.. speculating from the context here!

Originally posted by Darkpr0

Originally posted by emile
As we have known that, the more speed close to sonic, the more effect wave drag caused than friction drag. So there is nothing to do with wing area concerning the high speed maneuver.

True, but that wasn't quite was I was going for.
The idea is that in a WVR combat (be it with guns or missiles, I don't care) there's bound to be some very tight turns. Now while I've no doubt that this thing is incredibly zappy, the thing that makes me wonder is that the wing is so huge. As your speed decreases throughout the turn, I think the aircraft skids more and more (changing attitude while direction is still a few degrees behind). As this happens, more of the wing is exposed to airflow, and on a wing that size it's bound to be a lot of drag. That's the point I was trying to get across, sorry if it wasn't clear.

Eeerh.......

Let's make clear
This is turn
and
This is roll
So we can see that turn was concerned with L/D coefficient. While an aircraft make turn, the friction act but while aircraft make roll, the drage come from rudder such as flap, aileron more than surface of wing because the speed vector of wing in this period is vertical to the roll axis that also is airframe axis.
Back to the turn if you desire that. According to the link I given, in which you can see that angle banking gives the aircraft much mcuh more pressure(or say stress) than nature situation so that's why friction effect more.

reply to post by emile


but of course, how could I forget (and I see the image just fine)

I have some doubts about what functions will Tejas serve in IAF.

Means what actually is the meaning of Interceptor, Air Superiority a/c, Multi-Role a/c

As I think it is pointless comparing a table spoon with a tea spoon. Agree tea spoon is small but if we have to comment on it, it must be compared to a tea spoon and not table spoon.

All things man made are rubbish in God's viewsight
India give up Tejas will be equivalent to British abandoned TSR.2.

Originally posted by vedas
I have some doubts about what functions will Tejas serve in IAF.

Means what actually is the meaning of Interceptor, Air Superiority a/c, Multi-Role a/c

As I think it is pointless comparing a table spoon with a tea spoon. Agree tea spoon is small but if we have to comment on it, it must be compared to a tea spoon and not table spoon.

Ahh... there-in lies the answer to Tejas 'unique' design as well...
Her perceived roles have justified the given design..