Naval LCA - News and Discussion

Chinmay · Post by **Chinmay** » 28 Mar 2017 19:35

NRao wrote: Their claim. Rather impressive. SAAB does have a long history in such matters and have done a very good job at that. So, push comes to shve I would not discount them. But, point taken. IN and Brazilian Navy may/would need to fund such a plane.

Also, Brazil seems to be on their radar too, along with the IN. However, where are they going to get a carrier to test their ware on? Dunno.

Bala Vignesh wrote: Yup they have!! AI17 had quite a few naval pilots flying in it in customer evaluation flights..
Thanks.

Brazil cancelled its aircraft carrier. So the Sea Gripen is a no-starter as far as Brazil is concerned. We'll have to foot the entire cost, if the IN wants it.

brar_w · Post by **brar_w** » 28 Mar 2017 19:37

NRao wrote:
brar_w wrote:Sea Gripen remains a fully digital platform. Quite literally in that it exists purely in the digital realm and is likely to remain so indefinitely. Designing a carrier variant, and qualifying one for Catapult launch and arrested recovery is not an easy task and is unlikely to ever be company funded unless there is a major (as in three figure) order.
Their claim. Rather impressive. SAAB does have a long history in such matters and have done a very good job at that. So, push comes to shve I would not discount them. But, point taken. IN and Brazilian Navy may/would need to fund such a plane.

Also, Brazil seems to be on their radar too, along with the IN. However, where are they going to get a carrier to test their ware on? Dunno.

Thanks.

Brazil has decided to decommission its aircraft carrier. This leaves no one besides the Indian Navy that could potentially consider their proposal. Designing carrier changes in is a protracted, time consuming and expensive proposition not without pitfalls. And they have next to nothing in terms of experience. This is an area they could probably learn from the Indian side given its experiences with the Tejas.

Given that the Gripen-E is still, for all practical purposes, a mid-2020s fighter aircraft who is going to be looking to fund a CV variant for the 2030s when the Rafale-M, and Super Hornet are already available in the space and have plenty of potential to field upgraded capability by then? Not to mention the F-35B and F-35C. The JSF program would have reached a 12+ a month delivery (already at 5) by the time the Gripen-E declares IOC so once you factor in the cost and time to actually develop a variant and certify it you are looking at a higher bill compared to off the shelf purchase of F-35s.

SAAB would need a funding source (a desperate one at that), lots of time, a large order and an MOU with the US Navy for certification and help much like the RN is using on their ski test and SRLV program at Lakehurst and PAX River.

JayS · Post by **JayS** » 28 Mar 2017 20:45

Considering N-Gripen while rejecting NLCA is a plain mockery of logical thinking.

Perhaps SAAB will make a very good N-Gripen one day. But it would be too little too late.

Whatever SAAB marketing folks may say, even their own tech team would agree to the reality.

vasu raya · Post by **vasu raya** » 28 Mar 2017 21:05

brar_w wrote:Sea Gripen remains a fully digital platform. Quite literally in that it exists purely in the digital realm and is likely to remain so indefinitely. Designing a carrier variant, and qualifying one for Catapult launch and arrested recovery is not an easy task and is unlikely to ever be company funded unless there is a major (as in three figure) order.

Taking a tangent here, I have seen the video of the LA class SSN was fully designed in the digital realm first, down to the detail of maintenance needs. This was 20 years back.

Do such full scale artifacts exist for all the defence items that India is making, such as the NLCA, Su-30, Dhruv, Arjun MBT, LUH etc?

JayS · Post by **JayS** » 28 Mar 2017 21:50

vasu raya wrote:
brar_w wrote:Sea Gripen remains a fully digital platform. Quite literally in that it exists purely in the digital realm and is likely to remain so indefinitely. Designing a carrier variant, and qualifying one for Catapult launch and arrested recovery is not an easy task and is unlikely to ever be company funded unless there is a major (as in three figure) order.
Taking a tangent here, I have seen the video of the LA class SSN was fully designed in the digital realm first, down to the detail of maintenance needs. This was 20 years back.

Do such full scale artifacts exist for all the defence items that India is making, such as the NLCA, Su-30, Dhruv, Arjun MBT, LUH etc?

Guess you are referring to DMU -Digital MockUp. If yes then all the desi projects such as LCA, LUH etc have DMU. Su-30 is not our design so it may not have DMU. I am not too sure about legacy versions of Arjun and ALH but now they should have DMUs.

Do watch the video from AI 2017 Seminars on Concurrent Certification for HTT40 posted in Indian Mil Aviation thread.

brar_w · Post by **brar_w** » 28 Mar 2017 21:54

vasu raya wrote:
brar_w wrote:Sea Gripen remains a fully digital platform. Quite literally in that it exists purely in the digital realm and is likely to remain so indefinitely. Designing a carrier variant, and qualifying one for Catapult launch and arrested recovery is not an easy task and is unlikely to ever be company funded unless there is a major (as in three figure) order.
Taking a tangent here, I have seen the video of the LA class SSN was fully designed in the digital realm first, down to the detail of maintenance needs. This was 20 years back.

Do such full scale artifacts exist for all the defence items that India is making, such as the NLCA, Su-30, Dhruv, Arjun MBT, LUH etc?

I was referring to just a few folks in their PR department where the images of a variant are made. The have done some preliminary work a few years ago but it isn't nearly anything you will call a mature design by any standards.

The problem with the Naval Gripen is that any advantage in procurement or O&S cost that it enjoys over the Rafale-M and the Super Hornet is going to be more than offset by the upfront cost to design, certify and procure in small amounts. This will also hold true when pitted against a potential F-35B or C purchase.

vasu raya · Post by **vasu raya** » 28 Mar 2017 23:21

JayS wrote: Guess you are referring to DMU -Digital MockUp. If yes then all the desi projects such as LCA, LUH etc have DMU. Su-30 is not our design so it may not have DMU. I am not too sure about legacy versions of Arjun and ALH but now they should have DMUs.

Do watch the video from AI 2017 Seminars on Concurrent Certification for HTT40 posted in Indian Mil Aviation thread.

Taking the HTT-40 as an example, Its not just a digital mockup but a live design where they talk about those thousands of drawings that are integrated so a change anywhere is immediately impacting the rest of them like the switch from PW engine to Honeywell and they had regenerate about 2000 drawings. Maybe next time the airforce design team may want to give input in the design stage itself to weaponize Or Navy's design team wanting to try out modifications to make it Carrier capable

Added Later: I would take back that the DMU wasn't full fledged and it was indeed shared with Cemilac as well as the Production floor and probably can be done with end users as well.

vasu raya · Post by **vasu raya** » 28 Mar 2017 23:23

brar_w wrote: The problem with the Naval Gripen is that any advantage in procurement or O&S cost that it enjoys over the Rafale-M and the Super Hornet is going to be more than offset by the upfront cost to design, certify and procure in small amounts. This will also hold true when pitted against a potential F-35B or C purchase.

I would want to see a Rafale-M vs F-35B/C if its ever going to be.

disha · Post by **disha** » 29 Mar 2017 01:39

The real problem with Naval Gripen or Sea Gripen or Maritime Gripen is that it is a vapor ware currently and a good decade behind the NLCA Mk1.

Chances of NLCA Mk2 flying from the deck of IN Carrier are way higher than a Sea Gripen doing the same. Even for a demo.

At the same time this should not rule out IN asking for RFIs on Sea Gripen. RFI means just that 'Request for Information'.

srai · Post by **srai** » 29 Mar 2017 03:58

disha wrote:The real problem with Naval Gripen or Sea Gripen or Maritime Gripen is that it is a vapor ware currently and a good decade behind the NLCA Mk1.

Chances of NLCA Mk2 flying from the deck of IN Carrier are way higher than a Sea Gripen doing the same. Even for a demo.

At the same time this should not rule out IN asking for RFIs on Sea Gripen. RFI means just that 'Request for Information'.

With NLCA, India would be able to master both type of carrier systems: STOBAR (INS Vikrant) and CATOBAR system (INS Vishal).

JayS · Post by **JayS** » 29 Mar 2017 18:28

vasu raya wrote:
JayS wrote: Guess you are referring to DMU -Digital MockUp. If yes then all the desi projects such as LCA, LUH etc have DMU. Su-30 is not our design so it may not have DMU. I am not too sure about legacy versions of Arjun and ALH but now they should have DMUs.

Do watch the video from AI 2017 Seminars on Concurrent Certification for HTT40 posted in Indian Mil Aviation thread.
Taking the HTT-40 as an example, Its not just a digital mockup but a live design where they talk about those thousands of drawings that are integrated so a change anywhere is immediately impacting the rest of them like the switch from PW engine to Honeywell and they had regenerate about 2000 drawings. Maybe next time the airforce design team may want to give input in the design stage itself to weaponize Or Navy's design team wanting to try out modifications to make it Carrier capable

Added Later: I would take back that the DMU wasn't full fledged and it was indeed shared with Cemilac as well as the Production floor and probably can be done with end users as well.

Something interesting for you. Go to ADA website. look for Virtual Reality under Facilities Menu.

vasu raya · Post by **vasu raya** » 29 Mar 2017 19:49

Thank you JayS, seems like ADA laid the foundation but its application is still limited.

There may be a host of reasons for delays from requirements to concept to prototype to final config to user testing and induction, if one were to take the design in the digital realm, PRANA as ADA calls it, as a catalyst of the process and rate it, on a very limited sampling,

Advanced use of it,
Tejas - Air Force still suggests moving of LRUs so that its maintenance friendly
HTT-40 - Inspite of the DMU they had to modify the rudder, add balancing trims to the ailerons and pressurize the fuel tanks during testing but fast timeline nevertheless
ALH - there was talk of excessive tail rotor vibration, maybe doesn't have the backing of a mathematical model in specific areas?
LCH - it went through 3 prototype iterations before the final configuration

Can be used here,
Rustom 1 - Its first flight was back in 2009 and now being considered for weaponization with the requirement probably coming from the Army
Rustom 2 - Prototype and then undergoing weight optimization, probably can benefit from the HTT-40 development case study

and not just limited to aero structures,
Arjun - Army suggests 126 improvements
Namica - again numerous Army suggested improvements after User trials

srai · Post by **srai** » 29 Mar 2017 20:36

^^^

They are using DMU for Arjun MBTs and other armored vehicles.

JayS · Post by **JayS** » 29 Mar 2017 20:38

vasu raya wrote:Thank you JayS, seems like ADA laid the foundation but its application is still limited.

There may be a host of reasons for delays from requirements to concept to prototype to final config to user testing and induction, if one were to take the design in the digital realm, PRANA as ADA calls it, as a catalyst of the process and rate it, on a very limited sampling,

Advanced use of it,
Tejas - Air Force still suggests moving of LRUs so that its maintenance friendly
HTT-40 - Inspite of the DMU they had to modify the rudder, add balancing trims to the ailerons and pressurize the fuel tanks during testing but fast timeline nevertheless
ALH - there was talk of excessive tail rotor vibration, maybe doesn't have the backing of a mathematical model in specific areas?
LCH - it went through 3 prototype iterations before the final configuration

Can be used here,
Rustom 1 - Its first flight was back in 2009 and now being considered for weaponization with the requirement probably coming from the Army
Rustom 2 - Prototype and then undergoing weight optimization, probably can benefit from the HTT-40 development case study

and not just limited to aero structures,
Arjun - Army suggests 126 improvements
Namica - again numerous Army suggested improvements after User trials

You are greatly overestimating what DMU can do. Its just a PLM tool to do things more effectively. Its not panacea for all problems. Our fundamental issue is Project/Program Management. Both the user and the developer lack maturity needed to handle big and complex projects. The overseer, the MoD has people who neither have understanding nor the appreciation for technical things.

In all above things you listed the only real problem which was solvable using DMU was the maintenance issue with LCA. Its rather perplexing why those improvements popped up in 2015 or so.

vasu raya · Post by **vasu raya** » 29 Mar 2017 21:27

Agree that this is just one variable and it has its own evolution, don't know what the state of art is. so PRANA can include CFD for example? and not be disjointed.

The iterative improvements should be based on new requirements rather than a churn to the existing ones which happen because the user couldn't visualize them during design phase. Concurrent engineering can reduce the risk of calls to improve after User trials.

Kartik · Post by **Kartik** » 01 Apr 2017 01:54

Found another paper that talks about intake optimization for the LCA and the 3-door auxiliary intake has been finalized for the 3rd LCA Navy Mk1 prototype, NP5

INTAKE PERFORMANCE STUDIES FOR A GENERIC FIGHTER AIRCRAFT
CONFIGURATION

INTRODUCTION
Air intake performance is typically measured in terms of
flow variables at the intake aerodynamic interface plane (AIP).
The flow variables typically used to measure the intake
performance are pressure recovery and distortion which would
indicate the flow quality ahead of the engine face. The intake
design has to be such that the amount of flow non-uniformity
ahead of the intake face has to be as minimum as possible. In
the current study, a generic fighter intake geometry is selected
and certain design modifications were performed so as to
improve the intake performance at take-off conditions.
Change in intake lip and cowl profile under the constraints
of limiting changes to entry region of the duct; increasing
contraction ratio and implementing a 3-door AAID
configuration have been analyzed in this present study.

And from ADA's 2014-15 annual report, the 3-door AAID has been implemented on NP5 which is in build.

The
structural build of third LCA Navy Mk1
prototype, an additional two seat trainer
NP5 is under progress at HAL ARDC.
Fabrication of parts and sub-assemblies
are being carried out. The aircraft has
to be built close to production standard
incorporating modification and additional
functionalities compare to NP1 aircraft as
follows
Modifications:
1. Modified cockpit with 19deg Field of
View HUD
2. Ni-Cd Battery in place of Ag-Zn
battery
3. V/UHF Radio in place of INCOM
4. Implementation of three Auxiliary Air
Intake Door(AAID)
Additional LRUs:
1. SPJ POD integration
2. Laser Designator Pod
3. Air to Air Refuelling probe (as retro
mod)
4. HMDS
5. CMDS
6. TACAN
7. VOR/ILS
8. SLB
Build of Aircraft is progressing as per
schedule.

Kartik · Post by **Kartik** » 01 Apr 2017 02:01

Found a rendering of the LCA Navy Mk2 in ADA's Annual report 2014-15. What a beauty!!

JayS · Post by **JayS** » 01 Apr 2017 02:28

^^ From where you picked the picture:

The main
contributors to improvement in LCA(Navy) Mk2
have been identified as higher thrust engine,
an increased wing area, an area ruled and
streamlined configuration, lighter landing gear
and structure, and improved systems layout
towards better safety and maintainability.

For NLCA MK2:

Proposal to convert LEVCON into an
active surface permitting operations with
higher instability to achieve improved
agility and performance

Alternate ventral airbrakes performance with low interference.

Redesign of air intake for bigger GE-
F414-INS6 engine, with lip and cowl
profiles and auxiliary doors optimized for
superior performance at low speeds for
improved carrier launch capability

Mission performance analysis for three
IN profiles viz., Air Defence, Anti ship
and Ground strike were carried out. Point
performance compliance status with
respect to ASR was also evaluated.

Preliminary Structure Layout with zero
thickness model for NMG Version V0.06C for
Front, Centre & Rear Fuselage incorporating
1020 mm longitudinal plug, 700 mm
lateral plug. Concept studies of alternate
Structural Layout for iterations on Inboards
layout based on System requirement were
undertaken.

This is a new thing.

Study of TEX flap introduced for reducing approach speed to
suit carrier operations.
Feasibility study for usage of available
Electromechanical/Electro
hydraulic
actuators for Shelf flap was done.

Indranil · Post by **Indranil** » 01 Apr 2017 04:01

LCA Mk2 is not going to be pushover in the TWR section. But even then I do want to ask: If Vishaal is going to be catobar, how does TWR matter?

Kartik · Post by **Kartik** » 01 Apr 2017 05:29

And this as well for the LCA Navy Mk2

Improving performance in terms of low supersonic wave drag, acceptable cg limits for stability and control criteria for zero ballast design.

Zero ballast means 200 kgs weight shaved off.

The configuration study version that was most likely taken up for Detailed Design is V0.06C, the one that passed the PDR

The configuration identified as V0.06C has been defined as baseline for the Preliminary Design Review(PDR) of LCA(Navy) Mk2.

Preparation of structural design section of the PDR document of LCA(Navy) Mk2 has been completed.

A lot of work has gone into studying options for MLG, nose gear, fuel tanks, etc.

Structural layout for 3 options of Main Landing Gear(MLG) interface with Airframe was carried out. This involved studies for MLG load path and definition of structural attachment to fuselage. Structure layout for Nose Landing Gear(NLG) was also carried out. Arrestor hook structural
integration concepts for different schemes were carried out.

Different options of Fuel tank layout were studied to meet increased internal capacity as a fuel system requirement. Cockpit Layout iterations with vision requirements during approach for recovery on carrier, requirements study for panels and access covers etc., was carried out and
layouts prepared.

Airbus consultancy has helped significantly as acknowledged by ADA.

Indranil · Post by **Indranil** » 01 Apr 2017 10:29

Cassidian to be exact.

Austin · Post by **Austin** » 01 Apr 2017 11:05

Kartik wrote:Found a rendering of the LCA Navy Mk2 in ADA's Annual report 2014-15. What a beauty!!

Looks like Rafale Jr

JayS · Post by **JayS** » 01 Apr 2017 12:11

Indranil wrote:Cassidian to be exact.

Maybe you know this already - All the Defense and Space biz is consolidated under Airbus name now. Cassidian no longer exists as separate entity.

Indranil · Post by **Indranil** » 01 Apr 2017 21:21

I know. I was trying to specify which section of Airbus.

JTull · Post by **JTull** » 01 Apr 2017 23:20

Mk2 variant for both AF and Navy are increasingly looking to be completely new aircraft with 21st century tech instead of 80s/90s. Two generations of engineers have benefited from this program.

JayS · Post by **JayS** » 17 Apr 2017 16:08

x-posting from LCA thread. Can some adminullah move the relevant posts latest discussion from LCA thread here..?

sankum wrote:The IN RFI for 57 fighters is puzzling. IAC2 will not see service before 2030. Rafale will nor fit on either INS Vikramaditya or INS Vikrant as the wing span is around 11m with no wing folding and F35C with low thrust to weight ratio will not fit in STOBAR operations.

Only Candidate is F18E/F for which WOD requirement is relaxed to 30 knots as per RFI while for NLCA it is 20 knots. It is quite possible for 30 knots WOD NLCA meets IN requirement.

The cost of qualifying and developing customised version for IN for F18E will be prohibitive and the overall RFI is as far as I see in no go and just an information gathering exercise for future NAMCA.

Where did you get this information in the bolded part..??

I checked the RFI, it asks for information at 20kn and 30kn both for TO. I have never seen WOD spec for NLCA.

Link to RFI. See page 29 or 30 for TO related enquiry.
https://www.indiannavy.nic.in/sites/def ... 0Final.pdf

I am trying to understand the statement made by Cmd Balaji about relaxing requirement for new jet as compared to the NLCA. Since its RFI, IN has only asked for information and hasn't really specified any hard requirements. What am I missing..?

I see three main parameters affecting TO requirement.
- Configuration of the Aircraft - OCC, CC, MTOW?
- WOD. 20kn and 30kn mentioned in the RFI.
- TO run distance. IN has specified 3 distances each for two of its ACs.

As per, Cmd Balaji, its the last two which are relaxed. But I don't see how.

sankum · Post by **sankum** » 17 Apr 2017 16:38

It is from the slide in below URL for NLCA WOD is given as 15-20 knots while Cmdr Balaji said that it is relaxed for 57 fighter requirement.

Automated Take-Off From Aircraft Carriers For India's Naval Light Combat Aircraft [LCA-Navy]

As far as three distance in RFI it is 125m, 190m and 195m with 13 degree skijump in case of I assume INS Vikramaditya which basically implies that skijump is 13 degree and not 14 degree as reported in earlier reports and 144 m, 203m and 213 m in INS Vikrant with 14 degree skijump. The first two in both cases is with restraining gear stopping the wheels of fighter and in last case the fighter is on its own breaks or may be there are two restraining gears for redundancy in case of failure of one set and I think the second case is more likely.

A more likely aspect is that when two carrier group are active then each carrier are required to carry 20 fighters with surge load of 24 fighters. That basically means 48 fighters and a fleet of minimum 75 fighter with 65% availability for full utilisation of carrier air combat capability.

30 new fighters are required post INS Vikrant commissioning may be by 2019-20 and IN does not want MIg29K and the only other option is F18.

Hanger of INS Vikrant may be capable of handling F18 but INS Vikramaditya Hanger is too cramped to host F18.

JayS · Post by **JayS** » 17 Apr 2017 16:59

sankum wrote:It is from the slide in below URL for NLCA WOD is given as 15-20 knots while Cmdr Balaji said that it is relaxed for 57 fighter requirement.

Automated Take-Off From Aircraft Carriers For India's Naval Light Combat Aircraft [LCA-Navy]

As far as three distance in RFI it is 125m, 190m and 195m with 13 degree skijump in case of I assume INS Vikramaditya which basically implies that skijump is 13 degree and not 14 degree as reported in earlier reports and 144 m, 203m and 213 m in INS Vikrant with 14 degree skijump. The first two in both cases is with restraining gear stopping the wheels of fighter and in last case the fighter is on its own breaks or may be there are two restraining gears for redundancy in case of failure of one set and I think the second case is more likely.

A more likely aspect is that when two carrier group are active then each carrier are required to carry 20 fighters with surge load of 24 fighters. That basically means 48 fighters and a fleet of minimum 75 fighter with 65% availability for full utilisation of carrier air combat capability.

30 new fighters are required post INS Vikrant commissioning may be by 2019-20 and IN does not want MIg29K and the only other option is F18.

Hanger of INS Vikrant may be capable of handling F18 but INS Vikramaditya Hanger is too cramped to host F18.

Thanks for that data point. I have seen the seminar, but didn't remember. Well IIRC the INS Hansa ramp is 14deg and most probably exact replica of Vikrant's ramp. 200m TO roll matches with that of Vikrant.

I don't know much about it, but I would assume the length of TO roll must be depending upon the TOW. Longest for MTOW, shortest for A2A mission config.

Note that NLCA MK2 is suppose to have 16.5T MTOW, as per ADA guys in AI2017.

brar_w. any comment on possible MTOW for F/A-18 for STOBAR..?? I don't think the Americans have ever flown it on a ramp, so they will also be estimating it for now.

brar_w · Post by **brar_w** » 17 Apr 2017 18:19

brar_w. any comment on possible MTOW for F/A-18 for STOBAR..?? I don't think the Americans have ever flown it on a ramp, so they will also be estimating it for now.

Boeing did a little bit of modeling but nothing at the ramp since no customer ever showed great interest for such a capability.

srai · Post by **srai** » 17 Apr 2017 20:26

brar_w wrote:
brar_w. any comment on possible MTOW for F/A-18 for STOBAR..?? I don't think the Americans have ever flown it on a ramp, so they will also be estimating it for now.
Boeing did a little bit of modeling but nothing at the ramp since no customer ever showed great interest for such a capability.

STOBAR Carrier Ski-jump Simulator

© Artyom Beilis, 2015 - CC-By, JavaScript Code - MIT License

Abstract

Short Takeoff But Arrested Recovery (STOBAR) is one of the methods of designing a modern aircraft carrier. The aircraft takes-off using its own power rather than with the help of a catapult (CATOBAR). In order to takeoff from a limited deck space an inclined ramp or ski-jump is used. When the aircraft leaves the carrier from the ramp, it still does not have enough speed to be fully supported by its own wings, but it has a positive climb rate. The aircraft continues to accelerate losing its climb rate but gaining more airspeed and thus increasing the lift efficiently extending its "runway" length significantly.

There is a common misconception that heavily loaded aircraft cannot operate from STOBAR carriers and their capabilities are restricted to only very limited payload. This simulation allows to investigate various takeoff settings and find out whether specific aircraft is capable to takeoff from an STOBAR carrier and with which load.

It was clearly shown that F-18E/F at maximal allowed gross weight can takeoff from an STOBAR carrier within reasonable Wind Over Deck (WOD) requirements. Thus STOBAR carrier layout does not impose severe limitations on the maximal takeoff weight.

...
Conclusions

It was found that F-18E/F is capable of operating from STOBAR carrier even at maximal takeoff weight. Also Wind over Deck requirements for high loads aren't low they are reasonable.
...

JayS · Post by **JayS** » 17 Apr 2017 22:23

Good find. Simplified analysis, but shows that F/A-18 could handle significant TOW from STOBAR. At MTOW, the T/W ratio of F/A18 E/F is slightly better than the NLCA Mk2. NLCA MK2 will be a little worse than the F/A-18, but not by much.

sankum · Post by **sankum** » 17 Apr 2017 22:39

The above is a very simplified simulation of ramp take of. Just see the AoA graph (First graph in the video at 26.40 min)

"Designing And Testing Flight Control Laws Of Light Combat Aircraft [LCA] Tejas [Aero India 2013] "

The angle of attack is maintained constant at max AoA of 19.5 degree for 5 sec to maximize performance. ( Comparison of longitudinal axis parameters response with and without ramp take off mode).

You can see chart in the simulation of F18 that when maximum angle of attack is maintained for 5 sec the F18 performance will be far better than predicted.

The first 10 sec is engine warm off before the restraining gear is released in the video graph.

sankum · Post by **sankum** » 17 Apr 2017 23:30

My estimate is that for 30knots WOD NLCAmk1 should have MTOW of 13.5T (payload 2.9T) and NLCAmk2 MTOW of 16T to 16.5T(payload of 4t to 4.5T for empty weight guess of 8T). For 20knots WOD I have my doubts.

JayS · Post by **JayS** » 17 Apr 2017 23:36

sankum wrote:The above is a very simplified simulation of ramp take of. Just see the AoA graph (First graph in the video at 26.40 min)

"Designing And Testing Flight Control Laws Of Light Combat Aircraft [LCA] Tejas [Aero India 2013] "

The angle of attack is maintained constant at max AoA for 5 sec to maximize performance. ( Comparison of longitudinal axis parameters response with and without ramp take off mode).

You can see chart in the simulation of F18 that when maximum angle of attack is maintained for 5 sec the F18 performance will be far better than predicted.

The first 10 sec is engine warm off before the restraining gear is released in the video graph.

If you want details, see reference 5 from the link above, paper 20 or 21 may be in it. Gives data on actual F/A-18A flight testing off the ram. They did 91 flight tests. With that data, its not too much stretch of an imagination to say that the Rhino can surely TO with MTOW from a ramp.

Neshant · Post by **Neshant** » 18 Apr 2017 07:46

I wonder if thrust vectoring might help the nLCA get off the carrier with a full load.
For short takeoffs, the F-35's engine nozzle is literally tilted 90deg downwards for maximum lift.

I guess our carrier's ski jump provides a kind of "thrust vectoring" by directing the aircraft towards the sky.

But still... some physicists should examine if there are any benefits of thrust vectoring specifically for short takeoffs from ski jump carriers.

JayS · Post by **JayS** » 18 Apr 2017 08:42

Neshant wrote:I wonder if thrust vectoring might help the nLCA get off the carrier with a full load.
For short takeoffs, the F-35's engine nozzle is literally tilted 90deg downwards for maximum lift.

I guess our carrier's ski jump provides a kind of "thrust vectoring" by directing the aircraft towards the sky.

But still... some physicists should examine if there are any benefits of thrust vectoring specifically for short takeoffs from ski jump carriers.

You cant possibly tilt thrust vector 90deg for rolling TO elese there will be no forward thrust at all. It only works for VTO.

And you are forgetting about the Harriers. Incidentally British invented Ramp to assist TO of Harriers. They saw it reduces TO speed significantly. The Americans followed the que and tested F18 and F14 on ramp. They found out ~60% reduction in both the TO speed and the TO roll needed. And that too was with unoptimized 9deg ramp.

NLCA doesnt need Thrust vectoring which would also increase empty weight and reduce performance in the air further. It just needs a powerful engine or reduced flab. If only we could get F414 EE with 115kN thrust.

Bala Vignesh · Post by **Bala Vignesh** » 18 Apr 2017 09:43

May be not 90° but if we can manage to vector it by say 10°-20° it could help pull more load off the deck. To reduce complexity, it could be limited to a single direction.

Neshant · Post by **Neshant** » 18 Apr 2017 11:14

JayS wrote: You cant possibly tilt thrust vector 90deg for rolling TO elese there will be no forward thrust at all. It only works for VTO.

You can see what I'm talking about below. Its not 90 deg but probably closer to 45 on take off. Yet right after take off swivels to what looks closer to 90 deg. Now why it is even using 45 deg swivel on a ramp in the first place? It must be offering some kind of advantage in lift vs a trade-off in forward momentum. A physicsts should examine if there is anything to be gained by using slight thrust vectoring in aiding short take off from a carrier. That might well be the answer instead of hoping for a more powerful engine - which may never come! Foreign nations are in the business of screwing us over time & again.

https://www.youtube.com/watch?v=H2G36gH1ylI

NLCA doesnt need Thrust vectoring which would also increase empty weight and reduce performance in the air further. It just needs a powerful engine or reduced flab. If only we could get F414 EE with 115kN thrust.

I'm not talking about adding a heavy swivelling nozzle on the engine. I'm talking about plate deflectors (i don't know what else to call them).
Look at the back of the Shinshin's engine. Something like that isn't going to add significant weight and if it improves maneuverability in the air for a slight weight penalty - all the better.

Trying to think out of the box here.

JayS · Post by **JayS** » 18 Apr 2017 12:08

Neshant wrote:
JayS wrote: You cant possibly tilt thrust vector 90deg for rolling TO elese there will be no forward thrust at all. It only works for VTO.
You can see what I'm talking about below. Its not 90 deg but probably closer to 45 on take off. Yet right after take off swivels to what looks closer to 90 deg. Now why it is even using 45 deg swivel on a ramp in the first place? It must be offering some kind of advantage in lift vs a trade-off in forward momentum. A physicsts should examine if there is anything to be gained by using slight thrust vectoring in aiding short take off from a carrier. That might well be the answer instead of hoping for a more powerful engine - which may never come! Foreign nations are in the business of screwing us over time & again.

https://www.youtube.com/watch?v=H2G36gH1ylI

NLCA doesnt need Thrust vectoring which would also increase empty weight and reduce performance in the air further. It just needs a powerful engine or reduced flab. If only we could get F414 EE with 115kN thrust.
I'm not talking about adding a heavy swivelling nozzle on the engine. I'm talking about plate deflectors (i don't know what else to call them).
Look at the back of the Shinshin's engine. Something like that isn't going to add significant weight and if it improves maneuverability in the air for a slight weight penalty - all the better.

Trying to think out of the box here.

Please understand this - All you are trying to do is divert some power from already underpowered engine from longitudinal axis to vertical axis. You don't need Physicists to assess the situation. Engineers have already built and tested these systems for decades now. Its more efficient to produce lift by using thrust to increase speed. Thrust vectoring is rather inefficient way of getting lift. None of the VTOL aircrafts have TV merely to assist it in STO. On contrary, STO is used to increase TOW when VTO is not a necessity. Basically Ramp is to help reduce need/extent of TV, and not the other way round.

And you cant just TV at the fag end of the jet. It will pitch up the jet violently. Already there is excessive pitch rate in ramp TO at the exist. The FCS needs to keep the AoA in control. You can see how they had this issue in NLCA as well in the first flight. The pilot controlled the pitch up using stick input. See the Aero India Seminar on NLCA. Should be easy to find. So some part of the lift that you get from TV is lost in balancing the pitch up by creating negative left elsewhere and/or increasing drag significantly, unless you have additional vents, fan to balance it with thrust lift, creating which is too much work and impractical for NLCA.

Plate deflectors are very inefficient. You will see high loss in thrust. Normal circular TV itself can reduce thrust by 10% and F-22 style TV could reduce effective thrust by even 20%.

All those jets which have TV have significant excess thrust available. Putting TV on already underpowered jet is a bad idea.

BTW those deflector plats used in the Japanese jet are for the prototypes and as I expected they are temporary. They are developing proper TV a la Su-30 for the jet. The deflectors seems to be inspired from X-31. Its a easy and quick method to get TV, good for prototypes and experimental jets only.

In short, with TV, the effective thrust will decrease, using a part of it for lift is inefficient, and reduced thrust component in forward direction will only extend the time the jet needs to accelerate to the speed at which it can generate enough lift to hold itself in air.

shiv · Post by **shiv** » 18 Apr 2017 15:58

Thrust vectoring is a deliberate pre-designed add on an not an afterthought like car wedding decoration. Thrust that can move several thousand kg will blow away a thrust deflector unless there are some very powerful hydraulics to hold it steady in that exhaust airstream. All that adds weight.

A lot of Naval aircraft diverted their thrust downwards with zero weight addition by simply making the nosewheel longer so the plane looks like it is sitting on its ass, increasing the AoA while deflecting thrust down
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