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Round One JF17 - Poor Display By Tejas Took 10 more sec Than JF17 To Go Up

Please look at my post above. The ADA did look at it in the labs and did very through testing, the issue is your expectation with the design. The ADA chose a design based on meeting various criteria and with that design came its disadvantages which they tried to mitigate as much as possible. Credit goes to the CLAW team which really did very well in getting this design to work.

The rest is what and ANY other Indian will likely do in national fervour to try and justify it as some supermachine which it isnt nor ever will be. It is a fine fighter for the purpose it is designed to achieve; a Mig-21 replacement.
Sadly, it is this very "Superman" expectation that has left the program in doldrums along with other disasters such as Arjun.

As the thread shows, people of the subcontinent have issues with knowing exactly how much credit to take and give.. and realizing limitations. For them I have only pity, but none of my time.

As for the display, I will repeat my dissappointment....as I stated in my first post here. It is not disappointment in the Aircraft and its design, but how badly it has been managed that they are not willing to push it where its strengths are.


It has a role to play in the Indian Air Force Staff requirement for 2025 now, and for those roles this aircraft would be just satisfactory and the proposed Mk2 (if it happens and the Indian Babus both civilian and military dont screw it up) would be pretty good in.


Quite true..Oscar it isn't a super jet and it should have been completed a good 5-6 years back, it is a point defense replacement for mig21 and will take up the lowest rung of the IAF.

..It was "raped" by all and sundry - the force, the babus, the developers, the various lobbies, the think tanks, the ministry .. practically all.

The present government played a major part and practically threatened the developers, threw out a few research chiefs, cancelled other foreign contracts and bulldozed the LCA project forward.
 
Hi,

I did not get anything wrong---the JF17 is at designated ALTITUDE even with WHEELS DOWN faster.

Remember---during the paris show---I commented on the wheels down take off----. There is a reason for that.

Paf does not want to tell you its true climb rate----wheels down is pure drag---someone ask @gambit what a massive drag wheels down creates----how fast it bring the speed down from 600 knots down to 400 knots.

What happens if a jetliner lowers its landing gear at cruising speed? - Quora

Some answers in this link state that the landing gear might shear of due to drag---or wings might shear off due to drag---if landing gear was deployed during cruise of a commercial air liner at regular cruising speed----.

It acts like massive air brakes---. So----the paris show---tyhe JF17 takes off and gets to the flight ceiling with " air brakes on "---in lesser time.

just checking with you to ensure because Indians are complaining you got the timer calculation wrong. I want the critical analysis to be fair.

whatever JF-17 has displayed in the airshows is beyond exceptions of the general public. not because Indians have been trolling it but because we know the limits of China and Pakistan but what these jets pulled off was jaw dropping. so I agree in both cases ( Prance & China) the extreme manoeuver pulled off right after leaving the tarmac made me think the plane is going to stall and crash.

as for Tejas. well the Indians always oversold it and never compared it anything below the Western 4.5+ generation aircrafts (its been compare it to F22 in this thread as well). its flight display was very mediocre & restricted by design or by limitation apart from its vertical climb which I and many others have acknowledged as only noteworthy manoeuvre . you being NonPC .. said it what you felt and they didnt like it ( they like it and call you man of truth when the criticism is only against PAF).

I must say .. the good thing out of this thread is some very good, sombre and pragmatic posts have come out from some Indians which you and I have thanked and the thread has also deflated some abnormally oversized egos as well which they are failing to hide :)

How can we compare two aircrafts performance unless both pilots intended to do the same ?
How can we know what amount of internal fuel was carried on both aircrafts?
Tejas may not even carry radar in it .. ( ballast is still there )

So far we are analyzing what was only shown.
So we ll have wait for more air shows to fully see the capabilities.

As far as I see INTIAL OPERATIONAL CLEARANCE 1/2 aircraft did Good.
I agree, just good.. despite all the hype and nationalistic hysteria but the performance was . nothing beyond belief.. as any usual jet show goes.



. but for JF-17 ? for us and maybe you guys.. it was much more than usual good. since almost every Indian makes it a religious and national duty to call it a Mig 21 rip off and underpowered and paint job and for all that.. it did much more than good.

finally I agree its hard to have like for like analysis. both performed in different shows, did different maneuvers and are different designs so public has to make do with what it has in terms of airshow footage and compare the two.
 
You are throwing strawman arguments at what is not even up for debate in an attempt to avoid the primary issue which is poor program management.

Ok so has poor program management resulted in poor platform. If so, what is so poor about the platform. Kindly do not confuse the two so that we can learn what platform-specific issues you have squared in on.

Considering that everything beyond the 90's has been open arms to India, your entire argument falls flat on its face or only reaffirms the state of pithy bureucracy in India.

You have no idea. Sanctions are not there on systems. But you still, till today, cannot buy certain sub-systems off-the-shelf such as advanced gyroscopes and INS from USA. I don't know if other countries can but DRDO, HAL, ADA cannot. They will sell it to GCC, but GCC doesn't have any platforms in development. Once a country begins to threaten on developing competing platforms and sub-systems, it is a different ballgame, you lift the level of insecurity amongst suppliers to another level.

Considering that the CLAW team had access to US facilities and testing and the French gave massive input to the LCA design and testing along with the Israelis being ever present even before the nuclear sanctions gave up; it all points to gross indecisiveness or genuine lack of interest in the development team to get anything done for the aircraft.

After sanctions LM confiscated all that data and left the team willy nilly hanging onto air. Israel though is eager to please but does not have the testing facilities and wind tunnels and labs to validate everything.

Your beating around the bush posting paragraph after paragraph of semantics has nothing to do with the plain and simple truth of the Tejas being in its current conundrum solely due to poor utilization of resources by whosoever was managing the program from both the manufacturer's and customer's end.

I don't see what the issue is. It is true that apathy has caused a lag in development. But that lag period has been used for debugging and other critical areas. There was a waste of time but it isn't significant in overall context. Could it have been faster, yes it could.

Welcome to the forum, must say..that you would be a good addition to the Indian squad here..

Oscar isn't questioning the capabilities of Indians, he also knows the design, development issues. .what he is pointing out to the fact is ..The babudom issues and the external factors that screwed the LCA program...and I am in agreement with him on that fact.
 
Sure I would. All the technicians and scientists cannot change the laws of physics unless you wish to defined "Vedic Physics" which is the trend in India. The pitfalls of the delta were WELL KNOWN to the Tejas team but they chose to pursue it for their design constraints. It is called trade off in design to achieve requirements based on the needs of the user which are not always limited to aircraft performance. The biggest constraint being that the Tejas was told to be carrier capable which meant that it had to be a compact design, which is also where the compound delta has its play in trying to achieve the same aerodynamics as the M2K along with mitigating the issues that aircraft faces due to its pure delta design.

Moreover, the Tejas team.. like that on the F-22 did not achieve any miracle and essentially did the best they could with the budget given to them. Although in fairness, the F-22 had a much more flexible, and much less idiotic program management and indecisive customer than the Tejas has. To use the right stinging word, the Tejas program was essentially "raped" by the bumbling bureaucracy and poor cooperation between the IAF and the development team.
A fine aircraft that should have been on the front line some five years ago is still flying constrained and almost over cautiously due to mismanagement.


LCA was not considered for navy at start. Dont bring false reasoning here. Every design has its pros and cons. IAF was impressed on mirag. ADA just took it and redraw and try to mitigate drawback.

Important point is " Is your planes are good enough to take the advantage of Tejus' drawback?" Offcourse it isnt.
 
The compound geometry is NOT a canard attached to a delta. The compound delta is an attempt to solve the drag issue generated as shown in your figure by creating an energized vortex that allows for better manoeuvrability at supersonic speeds.

It essentially serves the exact same purpose as a canard in the configuration of a cranked delta. Naked Deltas already have better maneuverability at supersonic speeds, there is no case of making them all the more "better" there given the compression duct and expansion fan reversal of ideal gases.

Canards and compounds specifically address subsonic high alpha regimes for STR (among other things)...which is the naked delta wing's major weakness as you have stated at the speeds where this becomes a significant issue (notably in the transonic range).

Likewise... LERX, addition of TE reverse sweep, fiddling with aspect ratio in general and many other sorts of modifications help a conventional swept wing to have better supersonic maneuverability with due consideration given to aeroelastic effects etc (like why LM chose a diamond wing over a more conventional trapezoidal for the F-22).

In fact the use of LERX with a conventional swept wing uses the exact reverse incidence profile (high to low) as that of a cranked delta (low to high) because of the reversal from subsonic to supersonic I mentioned earlier and thus the mitigation aspect focus on the two different regimes for each major choice (conventional, delta). Do you want me to post the underlying aerodynamics and ideal gas theory here?
 
It essentially serves the exact same purpose as a canard in the configuration of a cranked delta. Naked Deltas already have better maneuverability at supersonic speeds, there is no case of making them all the more "better" there given the compression duct and expansion fan reversal of ideal gases.

Canards and compounds specifically address subsonic high alpha regimes for STR (among other things)...which is the naked delta wing's major weakness as you have stated at the speeds where this becomes a significant issue (notably in the transonic range).

Likewise... LERX, addition of TE reverse sweep, fiddling with aspect ratio in general and many other sorts of modifications help a conventional swept wing to have better supersonic maneuverability with due consideration given to aeroelastic effects etc (like why LM chose a diamond wing over a more conventional trapezoidal for the F-22).

In fact the use of LERX with a conventional swept wing uses the exact reverse incidence profile (high to low) as that of a cranked delta (low to high) because of the reversal from subsonic to supersonic I mentioned earlier and thus the mitigation aspect focus on the two different regimes for each major choice (conventional, delta). Do you want me to post the underlying aerodynamics and ideal gas theory here?


Sorry to intrude ,

Lerx & lev cons are same ?

It helps in lift for landing in decks, does it also work like canards in improving maneuverabilty ? Like improving turns
 
Lerx & lev cons are same ?

Levcons are the broad family, LERX is a specific member.

It helps in lift for landing in decks, does it also work like canards in improving maneuverabilty ? Like improving turns

Yes they can often serve the same purpose as canards do (both at all regimes of flight, however the range of most notable "impact" differs on the precise wing design regarding loading, aspect ratio etc) through vortex control at high alphas (when this is a major design intent to begin with)
 
Hi,

I did not get anything wrong---the JF17 is at designated ALTITUDE even with WHEELS DOWN faster.

Remember---during the paris show---I commented on the wheels down take off----. There is a reason for that.

Paf does not want to tell you its true climb rate----wheels down is pure drag---someone ask @gambit what a massive drag wheels down creates----how fast it bring the speed down from 600 knots down to 400 knots.

What happens if a jetliner lowers its landing gear at cruising speed? - Quora

Some answers in this link state that the landing gear might shear of due to drag---or wings might shear off due to drag---if landing gear was deployed during cruise of a commercial air liner at regular cruising speed----.

It acts like massive air brakes---. So----the paris show---tyhe JF17 takes off and gets to the flight ceiling with " air brakes on "---in lesser time.
Gear down is a large drag component, almost the equivalent to air brakes. Try to envision air flow INTO cavities -- landing gear bays. The higher the airspeed at the time of deployment, the higher the drag component overall on the aircraft.

Side note...Is it possible that the individual drag component on a landing gear is such that even hydraulics cannot fully deployed that particular landing gear ? Yes, possible. But we are talking about 3000 psi of hydraulics and if airflow is powerful enough to resist that, the landing gear bay doors would have been ripped off on opening and the result would be so violent that departure from controlled flight in pretty much inevitable. So this extreme is more FYI than related to the current discussion.

On an aircraft, do not confuse drag with mass (weight). Mass is a constant. A bomb will have zero drag if it is not moving but will still have X kilos. However, the bomb will have better (more efficient) FORM DRAG than the landing gear.

https://www.grc.nasa.gov/www/k-12/airplane/drag1.html
We can also think of drag as aerodynamic resistance to the motion of the object through the fluid. This source of drag depends on the shape of the aircraft and is called form drag.
Regarding drag, on an aircraft, the form drag created by the landing gears will exist one moment and disappear the next but the form drag created by the bomb remains, until the bomb is discharged, of course.

In order to have flight, thrust performance have to overcome both: Drag and Mass (weight).

This is the condition on take-off and easy to visualize...The landing gears's form drag are gone (retracted) but their mass (weight) remains as a constant, while the bomb's form drag and mass (weight) are constants. Remember, this is still on TAKE-OFF.

Look up images for F-15E fully loaded. That thing is NOT going vertical no matter how efficient are the form drag on those bombs. Put a rocket motor on it -- yes. Going into a powered dive then pull up -- yes.

On the other hand, an F-15C config-ed for air-air will have thrust performance such that it can go vertical after take-off even with all gears fully extended.

Now that we are clear on the difference between drag and mass (weight)...

The ideal test on the thrust performance of a fighter is when it is config-ed for the mission TYPES it was designed to do. If it means rig the jet with external stores -- do so. More important if the jet is multi-roles, which is pretty much all fighters today. I will put it this way: No pilot will want to fly and fight with less than what his jet is capable of carrying.

What this mean is that even if target estimate indicate two bombs will do, I will still want to fly with four if my jet is capable of carrying four. There are too many uncertainties between base and target. Even for a sniper whose credo is 'One Shot. One Kill' he will still go into the bush with as many rounds as he can carry.

On the other hand, going vertical or near vertical on a clean jet with gears extended is nevertheless an impressive demo, assuming that it was planned. You have both drag and mass. With landing gear handle down, there are logic that will send the flight control system (FLCS) into pre-sets, notably lowered gains on handling quality because it is assumed that the pilot want to take-off or land and is on a steady state flight path.

The logic is...

1- Landing gear HANDLE down. The system must know landing gear handle state if it is up or down and that knowledge is a physical switch.

2- Landing gear up condition is disengaged. The system is designed to look for a 0 if the landing gear is up. Not a null but a zero. Programmers understand the difference between a zero and a null.

3- Landing gear down condition is engaged. The system is designed to look for a 1 if the landing gear is down. When the landing gear is in transition, the system will receive nulls on both 'up' and 'down' conditions.

4- Land gear down LOCKED is engaged. This must be a physical switch.

Example of a discrepancy in logic: You cannot have the landing gear handle up but landing gears themselves are down and locked, meaning the down/locked switch is activated. You will get a warning light and landing gear warnings are always in-flight emergency (IFE) calls.

Once the logic chain is satisfied, certain flight parameters and authority are engaged such as g-limiting, trim limiting, leading edge (LE) and trailing edge (TE) flaps displacement, full rudder authority to the pilot since the rudder is usually commanded by the flight control computer (FLCC) in gear up flight, and there are others.

So for the JF-17 to have that AOA and powered to that altitude after take-off is either planned BECAUSE of a well designed aircraft or a blunder by the pilot. Take your pick.

there is difference between descending and falling.
True.

Sticking with aviation. In flight, the context of descending is always with control, as in there is an intent and ability to execute that intent. While falling is associated with descending, a fall implies there is no choice once underway. If you have the ability to execute a controlled descent, you also have the ability to leave it or go the other direction. A parachutist may have some controls over his descent, but he does not have the ability to return to higher altitude. Yes, I know of thermals, etc. But if thermals are not there, the parachutist will continues to the ground.

So how can you tell if an aircraft is descending or falling, especially from a video ? Not really. You can have a powered descent or a free fall descent.

To think a quadruplex FBW flight control system is going to get beat by the Thunder's pitch-only FBW in agility is beyond laughable.
Be careful. A WW I era biplane is actually more maneuverable than the F-16. But I do get the gist of what you said. Even so, for a FBW FLCS, it depends on the programming and the airframe that determines the limits of said programming, so in theory, the full three axes FBW system can be more limiting than the pitch only version.

Finally...There is a gross technical error in your comment. An aircraft have three axes: pitch, roll, and yaw.

You can have a full four-channels (quadruplex) FBW FLCS in pitch or in all three axes. The four channels is the design of the flight control computer (FLCC), not of the aircraft's axes, which falls under the laws of nature.
 
On the other hand, going vertical or near vertical on a clean jet with gears extended is nevertheless an impressive demo, assuming that it was planned. You have both drag and mass. With landing gear handle down, there are logic that will send the flight control system (FLCS) into pre-sets, notably lowered gains on handling quality because it is assumed that the pilot want to take-off or land and is on a steady state flight path.

Hi,

Even though I like the show of power---I do not think it was appropriate. I think it is too risky a maneuver---it really does not prove anything.

So---untill and unless paf gives an explanation of what they are doing---I truthfully cannot fathom it out.
 
This plane impressed me a lot. Take off in just 11 second inspite of the facts that 2 covers are used as the break on rare landing gear to reduce the speed. It they are removed, the timing will go up by 2 second further. Vertical flight was simply awesome. It performed double spin with such an ease. Vertical loop in just 17 second in last a spin and sudden change in direction. These were simply awesome. Now imagine a similar air show 1.5 to 2 years later. Weight of Tejas is slashed down to some 800 KG. The proposed aerodynamic improvements are done to reduce the drag by 8%. Another 5 to 6% aerodynamic improvement has come from adopting modern manufacturing practicing. T/W ratio has gone up by 15%. New nose cone is installed and wave Drag has reduced. AOA is increased to 28*. Plane has done 9+ g and and certified for 8+ gs.

Just imagine LCA Tejas Mk1+. it will emerge as the mini wonder and do what other aircraft can not even imagine to do. Look at that vertical fight of 20 second (Second). 10 second straight vertical and rest 10 second a steep climb. Now i have no doubt in my mind This is emerging as the one of the best light weight fighter of the world. Vivek Ahuja had rightly said that This plane shall beat F16 at low altitude and perform slightly better at high altitude. He further said that any weight reduction from this stage shall improve the performance of jet by a great margin. We are bloody reducing the weight by 800 KG. Air intake design shall also be improved. This will be a mini wonder like LCH specifically designed and made to meet IA requirement. Nothing in Indian neighborhood will match this plane except Su 30 mkk.
 
China wasnt technologically superior when it developed jf17....in terms of specs...tejas beats thunder(no offence meant for thunder which was supposed to be a cheap rip off of mig)


The guy has lost his credibility in the Indian circles....

Brother,

As a indian your point of view is understandable, but i think if we keep the facts clear then it will be better , like India developed 3.5th Generation Tejas, and China already developed 4th gen J-10, and 5th Gen J-11. My point is china is far head in terms of technology as compere to India.

Secondly i must say that their is no compression of Tejas and JF-17, because both planes have different characteristics.
 
Be careful. A WW I era biplane is actually more maneuverable than the F-16. But I do get the gist of what you said. Even so, for a FBW FLCS, it depends on the programming and the airframe that determines the limits of said programming, so in theory, the full three axes FBW system can be more limiting than the pitch only version.

Finally...There is a gross technical error in your comment. An aircraft have three axes: pitch, roll, and yaw.

You can have a full four-channels (quadruplex) FBW FLCS in pitch or in all three axes. The four channels is the design of the flight control computer (FLCC), not of the aircraft's axes, which falls under the laws of nature.

I am an amateur, I think maneuvering with out any flight disasters is what FBW will make sure. So a fighter jet with good FBW will always have advantage. (I mean with with good FBW which allows good maneuverability)
 
Gear down is a large drag component, almost the equivalent to air brakes. Try to envision air flow INTO cavities -- landing gear bays. The higher the airspeed at the time of deployment, the higher the drag component overall on the aircraft.

Side note...Is it possible that the individual drag component on a landing gear is such that even hydraulics cannot fully deployed that particular landing gear ? Yes, possible. But we are talking about 3000 psi of hydraulics and if airflow is powerful enough to resist that, the landing gear bay doors would have been ripped off on opening and the result would be so violent that departure from controlled flight in pretty much inevitable. So this extreme is more FYI than related to the current discussion.

On an aircraft, do not confuse drag with mass (weight). Mass is a constant. A bomb will have zero drag if it is not moving but will still have X kilos. However, the bomb will have better (more efficient) FORM DRAG than the landing gear.

https://www.grc.nasa.gov/www/k-12/airplane/drag1.html

Regarding drag, on an aircraft, the form drag created by the landing gears will exist one moment and disappear the next but the form drag created by the bomb remains, until the bomb is discharged, of course.

In order to have flight, thrust performance have to overcome both: Drag and Mass (weight).

This is the condition on take-off and easy to visualize...The landing gears's form drag are gone (retracted) but their mass (weight) remains as a constant, while the bomb's form drag and mass (weight) are constants. Remember, this is still on TAKE-OFF.

Look up images for F-15E fully loaded. That thing is NOT going vertical no matter how efficient are the form drag on those bombs. Put a rocket motor on it -- yes. Going into a powered dive then pull up -- yes.

On the other hand, an F-15C config-ed for air-air will have thrust performance such that it can go vertical after take-off even with all gears fully extended.

Now that we are clear on the difference between drag and mass (weight)...

The ideal test on the thrust performance of a fighter is when it is config-ed for the mission TYPES it was designed to do. If it means rig the jet with external stores -- do so. More important if the jet is multi-roles, which is pretty much all fighters today. I will put it this way: No pilot will want to fly and fight with less than what his jet is capable of carrying.

What this mean is that even if target estimate indicate two bombs will do, I will still want to fly with four if my jet is capable of carrying four. There are too many uncertainties between base and target. Even for a sniper whose credo is 'One Shot. One Kill' he will still go into the bush with as many rounds as he can carry.

On the other hand, going vertical or near vertical on a clean jet with gears extended is nevertheless an impressive demo, assuming that it was planned. You have both drag and mass. With landing gear handle down, there are logic that will send the flight control system (FLCS) into pre-sets, notably lowered gains on handling quality because it is assumed that the pilot want to take-off or land and is on a steady state flight path.

The logic is...

1- Landing gear HANDLE down. The system must know landing gear handle state if it is up or down and that knowledge is a physical switch.

2- Landing gear up condition is disengaged. The system is designed to look for a 0 if the landing gear is up. Not a null but a zero. Programmers understand the difference between a zero and a null.

3- Landing gear down condition is engaged. The system is designed to look for a 1 if the landing gear is down. When the landing gear is in transition, the system will receive nulls on both 'up' and 'down' conditions.

4- Land gear down LOCKED is engaged. This must be a physical switch.

Example of a discrepancy in logic: You cannot have the landing gear handle up but landing gears themselves are down and locked, meaning the down/locked switch is activated. You will get a warning light and landing gear warnings are always in-flight emergency (IFE) calls.

Once the logic chain is satisfied, certain flight parameters and authority are engaged such as g-limiting, trim limiting, leading edge (LE) and trailing edge (TE) flaps displacement, full rudder authority to the pilot since the rudder is usually commanded by the flight control computer (FLCC) in gear up flight, and there are others.

So for the JF-17 to have that AOA and powered to that altitude after take-off is either planned BECAUSE of a well designed aircraft or a blunder by the pilot. Take your pick.


True.

Sticking with aviation. In flight, the context of descending is always with control, as in there is an intent and ability to execute that intent. While falling is associated with descending, a fall implies there is no choice once underway. If you have the ability to execute a controlled descent, you also have the ability to leave it or go the other direction. A parachutist may have some controls over his descent, but he does not have the ability to return to higher altitude. Yes, I know of thermals, etc. But if thermals are not there, the parachutist will continues to the ground.

So how can you tell if an aircraft is descending or falling, especially from a video ? Not really. You can have a powered descent or a free fall descent.


Be careful. A WW I era biplane is actually more maneuverable than the F-16. But I do get the gist of what you said. Even so, for a FBW FLCS, it depends on the programming and the airframe that determines the limits of said programming, so in theory, the full three axes FBW system can be more limiting than the pitch only version.

Finally...There is a gross technical error in your comment. An aircraft have three axes: pitch, roll, and yaw.

You can have a full four-channels (quadruplex) FBW FLCS in pitch or in all three axes. The four channels is the design of the flight control computer (FLCC), not of the aircraft's axes, which falls under the laws of nature.

Hi Gambit,

If it's not much effort, can you post your observation regarding the LCA flight and jf17 flight.
 
Indians cannot fathom that their LCA is actually flying, most of them commenting here weren't even born when the project was conceived.

Imagine their inferiority complex when the first thing they want to do is a comparison with JF-17. I always hear PAF pilots and engineers compare JF-17 with F-16s as a benchmark, rather than a junk from India that for so long could never fly.
 
Indians cannot fathom that their LCA is actually flying, most of them commenting here weren't even born when the project was conceived.

Imagine their inferiority complex when the first thing they want to do is a comparison with JF-17. I always hear PAF pilots and engineers compare JF-17 with F-16s as a benchmark, rather than a junk from India that for so long could never fly.

This is the point that i do feel more proud of JF-17 that despite of all that expensive and advance technology in LCA god knows what more to be added, the benchmark to compare is still JFT, yet LCA still lacks a lot.
 
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