Indian Military Aviation- September 29 2013

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Re: Indian Military Aviation- September 29 2013

Postby abhik » 29 May 2014 22:55

nik wrote:Reliance is the only Indian player with balance sheet strength and interest in getting into building fighter jets.

Rest of the capable bunch - Tatas and Mahindra prefer small steps, not big leap of faith jumps.

If Reliance wants to make a big leap of faith then let them make the LCA.

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Re: Indian Military Aviation- September 29 2013

Postby Rahul M » 29 May 2014 22:59

given reliance's morals, or the lack of it I wouldnt want them within a 100 miles of our MIC.

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Re: Indian Military Aviation- September 29 2013

Postby VishalJ » 29 May 2014 23:57

rrao wrote:The air intakes are too small which may make the engine starved of the critical oxygen during high "g: Maneuvers?
The wing length and dimension appeared to be too small !!!
The location of air intakes should it be above or below the wings for an optimal flight performance.
IJT was hurriedly conceived in 36 months because of which it is suffering from congenital maladies...Gurus please comment on the soundness of the IJT design..
what are the corrective actions which our learned gurus can indicate .TIA!!!!


Image

Image

Really small intakes ^

Didnt make much of a sound on take-off, a Cessna 152 could've/would've done a better display than the one this one put-up :-?

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Re: Indian Military Aviation- September 29 2013

Postby Rahul M » 30 May 2014 00:01

has anyone mentioned size of intakes of IJT as an issue ? all ajt IJT have small intakes because the requirement isn't that large.

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Re: Indian Military Aviation- September 29 2013

Postby Raman » 30 May 2014 01:14

Intakes are sized as per required mass flow - an larger intake that attempts to push more air into the engine than the engine's mass flow rating will only result in spillage drag.

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Re: Indian Military Aviation- September 29 2013

Postby rakall » 30 May 2014 02:04

Raman wrote:Intakes are sized as per required mass flow - an larger intake that attempts to push more air into the engine than the engine's mass flow rating will only result in spillage drag.


IIRC, air intakes not an issue.. (based on recollection of the last comprehensive piece I read).. no

2 main issues :
1. stability issues during spin tests
2. MTBO of the engine

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Re: Indian Military Aviation- September 29 2013

Postby Indranil » 30 May 2014 02:05

rrao wrote:what is ailing with IJT?

1. wrong decsion to replace LARZAC with AL-55I
2. Russians ditching HAL to deliver a proven and reliable AL-55I in time ?
3 . flaws in the Aerodynamics design ,which is apparently causing an unwanted roll during stall tests?
4. Flight control systems are too lazy to respond?
5 .HAL has roped in BAe to help cllear IJT...how useful is it?
6. Retirement of project heads who conceived it?
7.new vigilance procedures have made the lives of designers miserable. Procurement is a nightmare with single tender issues,re-tendering and re-tendering causing an endless cycle..
8.of-course project management!!!


1 and 2. They had to go for a bigger engine. Going for AL-55I was certainly a mistake in hindsight. But at the time the decision was made, it did look quite good on paper.
3. Where did you read this? I have never read about uncommanded roll. What I have read is that during spins, the control surfaces are not effective enough to get out of the stall. But this is 1 year old news now. They have shed the vortex generators on the nose and the fences on the wings, and added vortex generators on the wings and also made them ribbed. They have fitted spin chutes and the tests have continued. We should wait for the test results.
4. Never heard of this before.
5. No.
6. Why? They took a bold initiative and we are going to go witch hunting with the benefit of hindsight?!!
7 and 8. No comments.

rrao wrote:IJT design is it based on Alpha jet or a polish trainer? The air intakes are too small which may make the engine starved of the critical oxygen during high "g: Maneuvers?The wing length and dimension appeared to be too small !!! The location of air intakes should it be above or below the wings for an optimal flight performance. IJT was hurriedly conceived in 36 months because of which it is suffering from congenital maladies...Gurus please comment on the soundness of the IJT design..
what are the corrective actions which our learned gurus can indicate .TIA!!!!

I have never heard of the IJT design to be based on anything. I have no idea on what basis you think the intakes are small (I have nothing more to add to what Raman sir said). For example this is the Hawk, the most successful jet trainer with an engine 1.5 times the size of IJT.

Image

Longer wing span is bad for maneuverability. I have never head of anything regarding insufficient maneuverability owing to wing loading. It is a simple design (exactly what it should be for a subsonic trainer). Intakes work best when they are away from any part of the body (including the wing) to avoid any buzz from the boundary layers. People place it under the wing or body of jet fighters for high alpha manuevers, so that the wing/body rams some incoming air into the air intake. This is not ideal but better than insufficient air. But not all jets do that (Mirage 2000, Mig-21, F-22, Gripen, Jaguars to name a few). I have never heard of IJT being starved of air.

15 years for design and certification along with an engine change is actually still good. There is urgency within the team. We should be a little more patient.

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Re: Indian Military Aviation- September 29 2013

Postby member_26622 » 30 May 2014 03:05

abhik wrote:If Reliance wants to make a big leap of faith then let them make the LCA.


I vote 100% for Reliance making LCA rather than the dressed up old dame called Rafale.

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Re: Indian Military Aviation- September 29 2013

Postby Manish_Sharma » 30 May 2014 04:02

What about L & T? They are making Arihant hulls, wouldn't they be more skillful at making a/cs then refinery + mobile making reliance?

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Re: Indian Military Aviation- September 29 2013

Postby chackojoseph » 30 May 2014 06:20

Anyone heard of Taneja Aerospace?


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Re: Indian Military Aviation- September 29 2013

Postby Austin » 30 May 2014 09:29

rrao wrote:what is ailing with IJT?


This is what AOC-in-C, Training Command, Air Marshal Paramjit Singh Gill said in Interview to FORCE in March 2014

Please comment on the status of the IJT programme.


It is already eight years behind schedule. We are hoping that IOC will be obtained by end of this year as by 2015 our Kiran assets will start dwindling. We are lucky that the Pilatus delivery is ahead of schedule, so some of the load of the Kirans will be taken by the Pilatus at Tambaram. That will give us some respite. However, by 2015 we need to have a replacement for the Kiran, so either the IJT comes up or we approach the government for an alternative. There are issues related to the stall and spin characteristics that need to be resolved; HAL is trying to resolve this. Once this is done, hopefully the progress will be much faster.


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Re: Indian Military Aviation- September 29 2013

Postby vic » 30 May 2014 12:41

Between Pilatus and Hawk, there is no urgency with IJT till 2020. If HTT-40 comes then between HTT-40 and Hawk, there may not even be any need of IJT. A fake urgent requirement of imports is being created by motivated parties.

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Re: Indian Military Aviation- September 29 2013

Postby rohitvats » 30 May 2014 12:57

vic wrote:Between Pilatus and Hawk, there is no urgency with IJT till 2020. If HTT-40 comes then between HTT-40 and Hawk, there may not even be any need of IJT. A fake urgent requirement of imports is being created by motivated parties.


Since you seem to know something which others don't, please answer these:

1. IAF has till now used 3 step process for fighter - HPT-32--> Kiran --> Mig-21 (MOFTU). Now, Pilatus fills in for HPT-32 while AJT plugs in for MOFTU. IJT is supposed to replace Kiran in IAF service. So, what exactly do PC-7 or AJT bring on table to do away with IJT requirement?

2. And if there is no IJT requirement now (even with Kiran being phased out), what will happen in 2020 which will require IJT in IAF service and hence, IAF can wait till then?

3. Now, since quantity of PC-7 and AJT ordered was keeping in view their original roles, wouldn't the number of these birds required increase if they (or anyone of them) also starts full filling role of Kiran in IAF service till the mythical HTT-40 comes on line?

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Re: Indian Military Aviation- September 29 2013

Postby John » 30 May 2014 20:00

indranilroy wrote:1 and 2. They had to go for a bigger engine. Going for AL-55I was certainly a mistake in hindsight. But at the time the decision was made, it did look quite good on paper.

I disagree many aviation analysts question the reason for this move and it smelled fishy, ofcourse mother russia crowd and MKI fans were ecstatic.

vic wrote:Between Pilatus and Hawk, there is no urgency with IJT till 2020. If HTT-40 comes then between HTT-40 and Hawk, there may not even be any need of IJT. A fake urgent requirement of imports is being created by motivated parties.

Vic, these reqs are primarily to put pressure on HAL and if nothing progresses a way for IAF to wash its hands clean off Sitara all together. Little late IMO could have done this 5 years ago.

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Re: Indian Military Aviation- September 29 2013

Postby chandanus » 30 May 2014 21:20

We are building a AF which has trainers from the Swiss , Advanced Trainers from the British , Fighters from Russia and France , Transports from The US..Upgrades from Isreal .... Zero Foresight in capability building ...they just blame everything on HAL ...Wtf !!!

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Re: Indian Military Aviation- September 29 2013

Postby vic » 30 May 2014 22:35

India should concentrate on developing and manufactering HTT-40, IJT and LCA trainer version. We have adequate amount of Pilatus, Kirans and Hawks to serve us till 2025 or more. Each stage requires around 60 hours of pilot training in total and a trainer aircraft can give 30-90 hours on average per month. Pls do your own calculations which will show there is no urgency except in the minds of bribe takers.

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Re: Indian Military Aviation- September 29 2013

Postby nachiket » 30 May 2014 22:42

rohitvats wrote:
1. IAF has till now used 3 step process for fighter - HPT-32--> Kiran --> Mig-21 (MOFTU). Now, Pilatus fills in for HPT-32 while AJT plugs in for MOFTU. IJT is supposed to replace Kiran in IAF service. So, what exactly do PC-7 or AJT bring on table to do away with IJT requirement?

That three step process made sense back then because the Mig-21U is a notoriously difficult aircraft to fly for rookies with minimal error margins while maneuvering, high landing speed and bad visibility from the cockpit. Even making the Kiran --> Mig-21 transition was difficult. However, the AJT does not suffer from any of those drawbacks. Most other air forces also seem to follow the Basic Trainer --> AJT route.

3. Now, since quantity of PC-7 and AJT ordered was keeping in view their original roles, wouldn't the number of these birds required increase if they (or anyone of them) also starts full filling role of Kiran in IAF service till the mythical HTT-40 comes on line?

Yes if the IJT is to be done away with, the Hawk numbers will have to increase.

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Re: Indian Military Aviation- September 29 2013

Postby vishvak » 30 May 2014 22:50

What will happen when time to retire the Hawk arrives eventually. After 2025 the same issues will appear after a decade again ie going back about how we didn't plan for HPT-40 a few decades back.

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Re: Indian Military Aviation- September 29 2013

Postby vic » 31 May 2014 00:08

As Lca is very close to Ajt, we can do HTT 40 to LCA if there are problems with IJT even beyond 2025

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Re: Indian Military Aviation- September 29 2013

Postby vic » 31 May 2014 10:39

vishvak wrote:What will happen when time to retire the Hawk arrives eventually. After 2025 the same issues will appear after a decade again ie going back about how we didn't plan for HPT-40 a few decades back.


That's what I am saying - Start to plan around HTT-40, HJT-36 and LCA AJT version for the coming decades.

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Re: Indian Military Aviation- September 29 2013

Postby rrao » 01 Jun 2014 11:28

Indranil sir,


Have you seen this ?

HAL struggling with jet trainer project

By Anantha Krishnan M - BANGALORE

Published: 10th October 2013 06:00 AM



Hindustan Aeronautics Ltd (HAL) is struggling with its Intermediate Jet Trainer (IJT) project, almost 10 years after the first prototype had its maiden flight.

Sources confirmed to Express that engineers and designers at HAL’s Aircraft Research and Design Centre have the daunting task of identifying and correcting the inherent asymmetry of the aircraft. The HAL hopes to get the Initial Operational Clearance (IOC) for IJT by the end of December, though insiders said the deadline might get pushed to next year.

“The issues related to aircraft have been reported by pilots during the ongoing tests and also endorsed by BAE Systems. This is coming in a large way for the ongoing stall and spin trials. Pilots had tried their best, but the aircraft rolls around 16 degrees, thereby forcing them to abort the stall tests,” a source said. The HAL had hired BAE Systems to act as consultants to evaluate the IJT’s stall and spin tests. While the HAL officially refused to give any project update on IJT saying “there isn’t much to share”, sources said the aircraft is scheduled to undertake crosswind trials at Jamnagar and cold weather trials at Srinagar.

“The IOC declaration might happen after these trials. One aircraft is likely to perform the stall and spin permutation and combination exercises in a parallel manner, to save time. The designers are even trying wing dressing so as to provide with the best stall experience. So far, all the prototypes coming out are having inherent asymmetry problems,” the official said.

The IJT, which was tipped to reap maximum benefits from HAL’s involvement in the Tejas project, lost its flight path completely in the last seven years following a spate of crashes and management issues. The Indian Air Force has been waiting patiently for the IJTs with the hope of filling the gaps in its training format. The HAL is committed to deliver 12 limited series production aircraft to the IAF and later 73 series production planes -- the deadlines all looking messier now.

Sources said IJT’s LSP-5 aircraft had its maiden flight during the last week of September, with a rolling off problem being reported on day one. However, the test flights of LSP-5 are currently on track, they said.

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Re: Indian Military Aviation- September 29 2013

Postby shiv » 01 Jun 2014 11:51

rrao wrote: “The issues related to aircraft have been reported by pilots during the ongoing tests and also endorsed by BAE Systems. This is coming in a large way for the ongoing stall and spin trials. Pilots had tried their best, but the aircraft rolls around 16 degrees, thereby forcing them to abort the stall tests,” a source said. The HAL had hired BAE Systems to act as consultants to evaluate the IJT’s stall and spin tests. While the HAL officially refused to give any project update on IJT saying “there isn’t much to share”, sources said the aircraft is scheduled to undertake crosswind trials at Jamnagar and cold weather trials at Srinagar.

“The IOC declaration might happen after these trials. One aircraft is likely to perform the stall and spin permutation and combination exercises in a parallel manner, to save time. The designers are even trying wing dressing so as to provide with the best stall experience. So far, all the prototypes coming out are having inherent asymmetry problems,” the official said.

The IJT, which was tipped to reap maximum benefits from HAL’s involvement in the Tejas project, lost its flight path completely in the last seven years following a spate of crashes and management issues. The Indian Air Force has been waiting patiently for the IJTs with the hope of filling the gaps in its training format. The HAL is committed to deliver 12 limited series production aircraft to the IAF and later 73 series production planes -- the deadlines all looking messier now.

Sources said IJT’s LSP-5 aircraft had its maiden flight during the last week of September, with a rolling off problem being reported on day one. However, the test flights of LSP-5 are currently on track, they said.


Does this mean that the aircraft refuses to stall by simply rolling away when they try to stall it?

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Re: Indian Military Aviation- September 29 2013

Postby Singha » 01 Jun 2014 12:23

Is this kind of issue supposed to be simulated and avoided in design or wind tunnel phase?

But i guess shit does happen as by the necessity to make the pylons on shornet as not straight ahead and wing fences.

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Re: Indian Military Aviation- September 29 2013

Postby saje » 01 Jun 2014 12:59

Irrelevant rant deleted. You're welcome to provide constructive criticism but such rant is not required. - rohitvats.
Last edited by rohitvats on 02 Jun 2014 10:50, edited 1 time in total.
Reason: irrelevant rant deleted.

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Re: Indian Military Aviation- September 29 2013

Postby Shreeman » 01 Jun 2014 13:21

shiv wrote:
rrao wrote: “The issues related to aircraft have been reported by pilots during the ongoing tests and also endorsed by BAE Systems. This is coming in a large way for the ongoing stall and spin trials. Pilots had tried their best, but the aircraft rolls around 16 degrees, thereby forcing them to abort the stall tests,” a source said. The HAL had hired BAE Systems to act as consultants to evaluate the IJT’s stall and spin tests. While the HAL officially refused to give any project update on IJT saying “there isn’t much to share”, sources said the aircraft is scheduled to undertake crosswind trials at Jamnagar and cold weather trials at Srinagar.

“The IOC declaration might happen after these trials. One aircraft is likely to perform the stall and spin permutation and combination exercises in a parallel manner, to save time. The designers are even trying wing dressing so as to provide with the best stall experience. So far, all the prototypes coming out are having inherent asymmetry problems,” the official said.

The IJT, which was tipped to reap maximum benefits from HAL’s involvement in the Tejas project, lost its flight path completely in the last seven years following a spate of crashes and management issues. The Indian Air Force has been waiting patiently for the IJTs with the hope of filling the gaps in its training format. The HAL is committed to deliver 12 limited series production aircraft to the IAF and later 73 series production planes -- the deadlines all looking messier now.

Sources said IJT’s LSP-5 aircraft had its maiden flight during the last week of September, with a rolling off problem being reported on day one. However, the test flights of LSP-5 are currently on track, they said.


Does this mean that the aircraft refuses to stall by simply rolling away when they try to stall it?


Here I go opening my mouth where it doesnt belong.

Here is what is typically done (everything is wrong from hereon) - pitch up (power on/off depending upon what you are teaching), at some pitch plane should stall, stall warning will sound if installed, and then variable behavior depending upon the aircraft prior to entering spin. A wing will dip, etc.

Stalls can occur inadvertantly, thus more than teaching, predictable stall/spin recovery/characteristics are imprtant aspects of flight certification.

This was all probably not needed to be said.

Now for the pitch angle, the statement is unclear. They appear to be saying a spin is unavoidable if they stall. Or that they dont stall the aircraft because they dont want to enter a spin with an odd roll. control surfaces may not be large enough to counter whatever assymetry is being seen, or roll/pitch interactions were not well understood during design.

Ps - Spin is a terrifying situation. worth experiencing if you like a near death experience.

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Re: Indian Military Aviation- September 29 2013

Postby shiv » 01 Jun 2014 13:33

Shreeman wrote:Now for the pitch angle, the statement is unclear. They appear to be saying a spin is unavoidable if they stall. Or that they dont stall the aircraft because they dont want to enter a spin with an odd roll. control surfaces may not be large enough to counter whatever assymetry is being seen, or roll/pitch interactions were not well understood during design.



That sounds like it. The thing decides to go for a spin (by starting to roll inexplicably) as nose is pitched up to reach stall conditions?

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Re: Indian Military Aviation- September 29 2013

Postby rohitvats » 01 Jun 2014 13:39

nachiket wrote:That three step process made sense back then because the Mig-21U is a notoriously difficult aircraft to fly for rookies with minimal error margins while maneuvering, high landing speed and bad visibility from the cockpit. Even making the Kiran --> Mig-21 transition was difficult. However, the AJT does not suffer from any of those drawbacks. Most other air forces also seem to follow the Basic Trainer --> AJT route.

<Snip>


If you're argument holds, then the very premise of having IJT ceases to exist. The project than is a white elephant and should be scarred forewith. Let IAF order more PC-7 and AJT to share the training requirement in both phases. And, let HAL work on next generation BFT and AJT/LIFT to cater for future requirement.

But since IJT has been ordered by IAF, I am assuming there are reasons for it related to flying training which might not be obvious as we speak. And let's hope IJT sees light of day sooner than later.

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Re: Indian Military Aviation- September 29 2013

Postby Shreeman » 01 Jun 2014 13:42

shiv wrote:
Shreeman wrote:Now for the pitch angle, the statement is unclear. They appear to be saying a spin is unavoidable if they stall. Or that they dont stall the aircraft because they dont want to enter a spin with an odd roll. control surfaces may not be large enough to counter whatever assymetry is being seen, or roll/pitch interactions were not well understood during design.



That sounds like it. The thing decides to go for a spin (by starting to roll inexplicably) as nose is pitched up to reach stall conditions?


A typical spin is predominantly yaw. Think of an elevator going down at jet speed while rotating around the verticle axis showing you 360 sights. You have a second or two to get out of it in a prop at 5k. Now if you are also rolling, it would be near impossible to figure out how to get out of a spin, that is what is up/down. Thus the parachute. Presume they have used it once or twice by now.

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Re: Indian Military Aviation- September 29 2013

Postby rrao » 01 Jun 2014 13:44

http://chinditsdefence.blogspot.in/search?updated-max=2014-05-07T14:24:00%2B05:30&max-results=50

imagine the fate of HAL if HR and Finance guys becomes Chairman!!!!


shiv sir!!! i got your jab!!! what to do!!! May be the IAF trainee rule book says what to do when aircraft stalls and spins...it doesn't say what to do if the a/c(IJT) refuses to stall first of all!!! :wink:
The unwanted roll may make regain control or ejection difficult!!!

singhaa sir, thats what i wanted to know whether its possible to evaluate a baby like IJT in 36 months with full fledged CFD evaluation in NAL wind tunnels,stall spin characterization using scaled down models....? Baby born with congenital malady?what's NAL wind tunnel experts take on IJT stall and spin performance? Do they see eye to eye with HAL?

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Re: Indian Military Aviation- September 29 2013

Postby shiv » 01 Jun 2014 13:53

Shreeman wrote:A typical spin is predominantly yaw. Think of an elevator going down at jet speed while rotating around the verticle axis showing you 360 sights. You have a second or two to get out of it in a prop at 5k. Now if you are also rolling, it would be near impossible to figure out how to get out of a spin, that is what is up/down. Thus the parachute. Presume they have used it once or twice by now.


The news item also says that there is some unexplained asymmetry (in the airflow presumably) that is causing the roll as they try to stall the aircraft so the stall test is called off. LSP 5 seems to have been built and it has done exactly the same thing from day 1. Weird stuff - but not outside the realms of possibility in new aircraft design. The thing simply has to be hacked, by hook or by crook.

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Re: Indian Military Aviation- September 29 2013

Postby Shreeman » 01 Jun 2014 13:56

What follows is wrong, my posts dont belong outside the cave.

After the disclaimer, there is this heresay -- certain skills are lacking. Not so long ago, I had this conversation with a yanqui gentleman who had been approached for a certain analysis of a different "baby" that I thought would have been key prior to realization of a prototype.

Also, manufacturing precision and new engine in the mix.

The vertcle tail is huge in training aircraft. Look at the yak-130 M-34x, chinese clone etc. All tail and no plane. There is significant weight distribution difference/control surface malfunction between planned and actual or roll should not occur to the extent mentioned.

Solvable problems, consultants want more money or have something else to sell you.

Dont hold me to ^^^^. I never said it.
Last edited by Shreeman on 01 Jun 2014 14:00, edited 1 time in total.

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Re: Indian Military Aviation- September 29 2013

Postby shiv » 01 Jun 2014 13:57

rrao wrote:shiv sir!!! i got your jab!!! what to do!!! May be the IAF trainee rule book says what to do when aircraft stalls and spins...it doesn't say what to do if the a/c(IJT) refuses to stall first of all!!! :wink:


Well aircraft with foreplanes like Rutan's Vari-eze supposedly do not stall because the foreplanes stall first, lose lift and drop the nose before the main wings stall - or some such explanation (I think)

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Re: Indian Military Aviation- September 29 2013

Postby shiv » 01 Jun 2014 14:00

Shreeman wrote:
After the disclaimer, there is this heresay -- certain skills are lacking. Not so long ago, I had this conversation with a yanqui gentleman who had been approached for a certain analysis of a different "baby" that I thought would have been key prior to realization of a prototype.


Dont hold me to ^^^^. I never said it.


What you have not said was also not said to me over no coffee consumed by another BRFite about another baby - let me name it - Kaveri.

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Re: Indian Military Aviation- September 29 2013

Postby Shreeman » 01 Jun 2014 14:01

shiv wrote:
Shreeman wrote:
After the disclaimer, there is this heresay -- certain skills are lacking. Not so long ago, I had this conversation with a yanqui gentleman who had been approached for a certain analysis of a different "baby" that I thought would have been key prior to realization of a prototype.


Dont hold me to ^^^^. I never said it.


What you have not said was also not said to me over no coffee consumed by another BRFite about another baby - let me name it - Kaveri.


Different baby, easier skill in my case.

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Re: Indian Military Aviation- September 29 2013

Postby vic » 01 Jun 2014 15:31

I think with the impending induction of LCA in mass numbers, the three stage progarmme is redundant. We should use HTT-40 and then straight to LCA Trainer.

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Re: Indian Military Aviation- September 29 2013

Postby chackojoseph » 01 Jun 2014 16:02

While no news on NDA government over Rafale

Indo-French bilateral Air Exercise - Garuda-V begins on June 2

Rafales and KC-135 coming.

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Re: Indian Military Aviation- September 29 2013

Postby rrao » 01 Jun 2014 16:15

Shreeman wrote:What follows is wrong, my posts dont belong outside the cave.

After the disclaimer, there is this heresay -- certain skills are lacking. Not so long ago, I had this conversation with a yanqui gentleman who had been approached for a certain analysis of a different "baby" that I thought would have been key prior to realization of a prototype.

Also, manufacturing precision and new engine in the mix.

The vertcle tail is huge in training aircraft. Look at the yak-130 M-34x, chinese clone etc. All tail and no plane. There is significant weight distribution difference/control surface malfunction between planned and actual or roll should not occur to the extent mentioned.

Solvable problems, consultants want more money or have something else to sell you.

Dont hold me to ^^^^. I never said it.


shreeman shiv sir, please catch hold of shreeman shreeman sirji and take him to HAL honcho. After all , a flurry of R&D agreements are being signed up with IITs these days by GMs. Shreeman sir somehow smells HAL to me..... :D

deejay
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Re: Indian Military Aviation- September 29 2013

Postby deejay » 01 Jun 2014 17:11

saje ji:

I some times wonder whether the intermediate jet trainer used currently by the Pakis & Cheens will pass muster in the IOC/FOC tests of the IAF! If there is a problem with stalls & spins in the IJT, then the simple work around is to NOT make it stall & spin. Why can't the trainees learn about stalls & spins in the Pilatus & then in the AJT?


If the aircraft is having problems in stalling, then I guess it is not the IAF that can say - "We will not train for stall and spin". AFAIK the stall characteristics of the aircraft will help define the maneuver envelope of the aircraft. You may check the link which is slightly technical but easy to understand : http://www.propdesigner.co.uk/html/maneuvering_envelope.html

You may also check the wikipedia entry on the subject (It is more layman)

Stall tests are also good way to determine the aircraft low speed handling. Especially since landing speeds are slightly higher than stalling speeds so an aircraft tending to roll at stall would be tough to handle. In the hands of a trainee, with less than 100 hrs experience - really not what anyone would want. (OT: The stall and spin characteristics of each aircraft varies, especially with change in wing shape. Again, AFAIK, Delta winged aircrafts are difficult to stall.)

The truth is that the IAF is digging itself into a big hole with it's high expectations & inflexibility and it expects HAL/NAL/DRDO to pull it out of that hole.


The reason IAF has these stall / spin expectations from an IJT is because, the stage II trainer will be used to teach and train trainee pilots high 'g' maneuvers. These maneuvers are in form of aeros and combat profile. The chances of stalling and spinning in such situation remains high and a pilot must understand both the symptoms and recovery from such a situation. (Qualifier: this is only my opinion based on some lectures attended, field work and first hand interaction with IAF QFI's , I have not read any literature on this). So learning to Stall and Spin is vital and not just some IAF quirk.

Hence, the need to stall & spin the IJT is something that the IAF requires for itself not something it has heaped on HAL.

rrao
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Re: Indian Military Aviation- September 29 2013

Postby rrao » 01 Jun 2014 17:41

Deejay ji,nice post!!!! what according to you is the reason behind the unwanted roll? Basic flaw in the aircraft design , wing shape, wing area, mass unbalance around the roll axis etc... can we use the signal from stall warning and with the help of a MEMS gyro measure the roll during stall and activate the control surfaces which cause a roll to correct the roll... Redesigning the whole craft is as good as scrapping it!!!


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