[amitk26]

Originally Posted by MinivanDriver

@V.Narayan, I have heard that the pusher props came with a base design bought out from Piaggio by NAL. The current design may be an evolution of that rather than clean sheet. (@sandeepmdas, SARAS seems to be based on a predecessor of the Avanti)

SARAS is not based on Avanti but in 1991 India tied up with Myasischev Design Bureau of Russia as joint project.
They had similar program called Myasischev Duet M-102

However soon priorities changed and Russians dropped out and program was taken over by NAL fully.
India wanted to use Pratt and Whitney engines and Russians were insisting on their own.

There was typical new learning curve, unrealistically small budgets and delays associated with other such project where foreign collaboration was stopped ( Read Tejas and GE Engine Saga)
Here is a picture of Myasischev Duet M-102 , The project was later abandoned in Russia.

[SmartCat]

Gentlemen, how "safe" are these small 10 to 20 seater turboprops when compared to ATR 72 or 737 or A320? Short distances mean they probably do a lot more take offs and landings. Do these birds too have multiple redundancies like big airliners?

[amitk26]

Originally Posted by smartcat

Gentlemen, how "safe" are these small 10 to 20 seater turboprops when compared to ATR 72 or 737 or A320? Short distances mean they probably do a lot more take offs and landings. Do these birds too have multiple redundancies like big airliners?

Pretty safe I guess example HAL built 125+ Do 228 and they have excellent record.

[srvm]

My 2 bit on this topic.

The following is from NAL's webpage:

NAL's Mission

Development of national strengths in aerospace sciences and technologies, infrastructure, facilities and expertise.

Advanced technology solutions to national aerospace programmes, fighter aircraft, gas turbine engines, defense systems, defense services, launch vehicles & satellites, and space systems.

Civil aeronautics development (from 1994). Design and development a small and medium-sized civil aircraft - To promote a vibrant Indian civil aviation.

NAL's Mandate

NAL's mandate is to develop aerospace technologies with a strong science content, design and build small and medium – sized civil aircraft, and support all national aerospace programmes.

One can observe that NAL aims to be like NLR, DLR, NASA on one hand while also trying to be Embraer, Alenia, HAL etc. on the other. This while not being an independent entity with full autonomy. Instead, it is one of the CSIR labs with some degree of autonomy. And their full strength is about 1000 including non-scientific staff (compared to about 20,000 in Embraer).

This identity crisis, if one may call it that, is one of the prime reasons why NAL is unable to spearhead delivery of high-class aviation products.

True, they have contributed a lot to Indian Aeronautical and Space programmes as collaborators.

[V.Narayan]

Originally Posted by Jeroen

How does the certifying of military versus commercial planes work in India? If you would design and certify a plane as a military plane, would it be easy to get the commercial certification afterwards. Or would you go the other way?

The other day we were discussing certification and they will always run the program as if it was a civilian airplane. So they will start with a civilian registration, certify whatever needs certifying as they do God knows how many modifications to the airframe.

The correct way is as you have described it in paragraph 2 put in underline by me. The civil needs will always be more stringent than the military ones and preparing for civil from day one is the correct or normal way to go if it will be used for both customers. Military certifications are fairly common and have a well established procedure. We have produced a few successful military aircraft {HF-24, Kiran, HPT-32, Dhruv, Rudra, Tejas} and numerous major modifications or upgrades. As you know military certification is simpler. On the civil side our knowledge and experience is not there like with EASA or FAA. Simply because there have been very few Indian designed and successfully built civilian aircraft - single engine pistons in the '60s and '70s and civil version of Dhruv. We do have some experience in certifying foreign licenses built here for civil purposes - HS748 and Do228. I would think there is a steep learning curve ahead even for the regulator to develop the know-how of a full fledged commuter turboprop. The reason I said that it will be better if they get the CEMILAC approval and put the machine in real service is that it will need one or two years of maturing in real operational flying before all snags and early improvements can be cleaned up and make it truly ready for passenger flying.

Originally Posted by amitk26

HAL already has production license of Dornier 228 ( 19 seater) and they have produced and sold 125+ DO 228 to military users.Coming to NAL SARAS it is 14 seater the rational behind it was to replace Do 228 for IAF and the new design is supposed to give higher fuel efficiency and range also the service sealing is higher and cabin is pressurized. I think it is not right to deride this effort.

Dear amitk26, Not deriding the effort but having seen this story repeat itself several times with each story stretched over 15 to 25 years I have a few grains of skepticism. These programmes almost always start of with a vain objective which has little co-relation to what has been achieved earlier and then burns taxpayers money for years on end. In my opinion we should have developed on the Do228 either on our own or together with RUAG. The Do228 is an excellent machine with one of the {still}most efficient wings in that weight category. Also the 2009 crash should not have stalled the programme. Crashes are sad and tragic personal events but a reality in aircraft development.

How the Brazillians went about developing the EMB 110 is a text book example of how it is done if you have a 50 year vision. That story is for another day.

Originally Posted by srvm

The following is from NAL's webpage:

One can observe that NAL aims to be like NLR, DLR, NASA on one hand while also trying to be Embraer, Alenia, HAL etc. on the other. This while not being an independent entity with full autonomy. Instead, it is one of the CSIR labs with some degree of autonomy. And their full strength is about 1000 including non-scientific staff (compared to about 20,000 in Embraer).This identity crisis, if one may call it that, is one of the prime reasons why NAL is unable to spearhead delivery of high-class aviation products.

Thank you for putting it so well. It is an identity confusion. For this the blame lies not with NAL but our higher leadership who have failed to think through and implement a coherent national policy for aeronautical development. Then what happens is that each Govt body jostles for funds by putting up projects that may catch the eye. Nehru to his credit took atomic energy, space and aeronautical development as his personal babies and had a vision. The 1950 to 1965 period was our best in making progress on design of our own successful planes {Marut, Kiran, HT-2, Pushpak, Krishak} as well as license production en masse of foreign designs {Gnat, Alouette, MiG-21, HS748}. Because of this lack of subsequent vision in aviation we are still barely walking literally 57 years after having flown the Marut. In ship building in the same time we have gone from our first license design to mature destroyers to nuclear powered submarines. In ISRO in the same time we went from the Thumba weather rocket Rohini launches to Mangalyaan.

Reviving a design after 9 years is not easy - people change, collective team memory fades etc. Effectively one ends up re-starting.Having reached this far I genuinely wish the current NAL-HAL team success - we cant blame them for the mistakes of 10 or 20 years ago or the lack of policy which lies at the doorstep of the IAS.

Originally Posted by smartcat

Gentlemen, how "safe" are these small 10 to 20 seater turboprops when compared to ATR 72 or 737 or A320? Short distances mean they probably do a lot more take offs and landings. Do these birds too have multiple redundancies like big airliners?

Down to the 30-seater category they are safe as safe can be. They carry multiple redundancies and avionics to match the bigger aircraft within the parameters of the shorter legs they fly. When you hit the 19 and 14-seater stage you could get unpressurized and fixed landing gear and in many cases simpler avionics. But avionics today are very very good even in the austere versions. Don't worry. If you are flying at 350 kmph the crash landing isn't too hard. :-)

[Sutripta]

Originally Posted by sandeepmdas

Me no tech guy, but the pusher props are notorious for their noise.

At least the internal noise levels should be low!
What would be the technical reason for pusher props to be noisier on the ground?

Originally Posted by V.Narayan

The FAA cautioned Embraer that this unique tail set up will require significant extra testing for flight safety certification.

Why significantly different from rear engined jets, which are common enough?

On a different matter, where do we now stand with Ecuador?

Regards
Sutripta

[niranjanprabhu]

Originally Posted by smartcat

Most turboprop aircrafts have propeller infront of the engine like this -

Attachment 1745437

But NAL Saras has propeller behind the engine.

Attachment 1745438

Any idea why this is so? Does mounting propeller behind the engine have any particular cost advantages?

My dear friend wing commander Praveen was the pilot of the ill fated Saras that crashed on 2009 March 6th

This question you have asked is very pertinent. The propeller fans turned backwards have the advantage of giving extra thrust to the plane but at the same time it has the issue of creating instability to the aircraft. Will be happy to field more questions on this as it effected me at a very personal level

[SmartCat]

Originally Posted by niranjanprabhu

My dear friend wing commander Praveen was the pilot of the ill fated Saras that crashed on 2009 March 6th. This question you have asked is very pertinent. The propeller fans turned backwards have the advantage of giving extra thrust to the plane but at the same time it has the issue of creating instability to the aircraft. Will be happy to field more questions on this as it effected me at a very personal level

Sorry for you loss. But what's your take on NAL chief's statement on 2009 crash? What does he mean by "procedural mistake"? He first says there were no design glitches but then in the next line says there were design deficiencies.

Jitendra J Jadhav, the chief of National Aerospace Laboratories, told NDTV that they have found that the crash was caused by a procedural mistake, not a design or manufacturing glitch. But there were a "lot of design deficiencies, which have been rectified quickly by our team, mainly those handling quality and controllability of the aircraft and digital avionics," he added

Originally Posted by V.Narayan

In ship building in the same time we have gone from our first license design to mature destroyers to nuclear powered submarines. In ISRO in the same time we went from the Thumba weather rocket Rohini launches to Mangalyaan.

One reason could be that there are only a handful of jet engine manufacturers and largish passenger aircraft makers. And they have always been ultra sensitive about doing a full tech transfer (designs, drawings etc). At best, these guys transfer just enough technology to do a basic assembly.

But that doesn't seem to be the case with Western ship or submarine building companies (DCNS, Russians etc). They are much more receptive to tech transfer if you show them the money.

Any idea how ISRO managed to prevent bureaucracy and politicians from ruining things?

[V.Narayan]

Originally Posted by Sutripta

What would be the technical reason for pusher props to be noisier on the ground?

This is what I think I remember - a pusher prop turns in air already disturbed by having to pass over the airframe and wings before reaching the props. That results in a higher percentage of the propellers turning energy getting converted to vibrations i.e. higher noise.

Why significantly different from rear-engined jets, which are common enough?

The airflow created by a large slow turning un-encased prop is significantly different from an encased turbofan pushing a horizontal column of gas to the rear. Air being a light fluid can behave very differently with even slight changes (of a few centimeters) in airframe design.

On a different matter, where do we now stand with Ecuador?

I have not kept track after Ecuador decided to sell the remaining 3 of their fleet of 7. The other 4 having crashed over a few years after the induction in 2009. While the first crash was attributed to pilot error the cause for the other three is disputed. Ecuador cancelled the contract in 2015 thus cutting off supply of spares and support. Without detailed facts it is hard to pin the blame between design, manufacture, inadequate training, pilot competence, engineering support etc. It was a big win when it happened and it is so very sad it has ended this way. I have direct experience of operating the Dhruv for 600 hours a year with some very difficult and specialized flying. It has served us well with no complaints of consequence on the machine itself. Logistics support and customer service could be a lot better.

[niranjanprabhu]

Originally Posted by smartcat

Sorry for you loss. But what's your take on NAL chief's statement on 2009 crash? What does he mean by "procedural mistake"? He first says there were no design glitches but then in the next line says there were design deficiencies.

Jitendra J Jadhav, the chief of National Aerospace Laboratories, told NDTV that they have found that the crash was caused by a procedural mistake, not a design or manufacturing glitch. But there were a "lot of design deficiencies, which have been rectified quickly by our team, mainly those handling quality and controllability of the aircraft and digital avionics," he added



One reason could be that there are only a handful of jet engine manufacturers and largish passenger aircraft makers. And they have always been ultra sensitive about doing a full tech transfer (designs, drawings etc). At best, these guys transfer just enough technology to do a basic assembly.

But that doesn't seem to be the case with Western ship or submarine building companies (DCNS, Russians etc). They are much more receptive to tech transfer if you show them the money.

Any idea how ISRO managed to prevent bureaucracy and politicians from ruining things?

The test that caused the crash was one of the last tests that are conducted on a plane of this kind. It involves switching off the engines mid air and restarting them again. Its a dangerous test. This test was to be done at 25000 feet but was wrongly conveyed to the pilots to be conducted at 10000 feet. This is what caused the tragedy

[SmartCat]

Originally Posted by niranjanprabhu

The test that caused the crash was one of the last tests that are conducted on a plane of this kind. It involves switching off the engines mid air and restarting them again. Its a dangerous test. This test was to be done at 25000 feet but was wrongly conveyed to the pilots to be conducted at 10000 feet. This is what caused the tragedy

Now that really hurts. During such tests, only one engine is switched off right?

I can imagine what kind of nerves one needs to have to be a test pilot for an untested Indian made passenger (no ejection seats) aircraft .

[niranjanprabhu]

Originally Posted by smartcat

Now that really hurts. During such tests, only one engine is switched off right?

I can imagine what kind of nerves one needs to have to be a test pilot for an untested Indian made passenger (no ejection seats) aircraft .

No both were switched off :(
Just google for the DGCA report of this crash. its downloadable.

[SmartCat]

Originally Posted by niranjanprabhu

No both were switched off :(
Just google for the DGCA report of this crash. its downloadable.

Found the 75 page DGCA report on the crash
http://dgca.nic.in/accident/reports/VT-XRM.pdf

[Sutripta]

Originally Posted by V.Narayan

The airflow created by a large slow turning un-encased prop is significantly different from an encased turbofan pushing a horizontal column of gas to the rear. Air being a light fluid can behave very differently with even slight changes (of a few centimeters) in airframe design.

The same should hold for conventionally mounted (ie pods from main wing) engines, whether prop or jets. Are the characteristics, and thus what is checked in the certification process, radically different.

OT - Was the BAE 146 quiet by design (and if so, what elements of the design contributed to it. After all 4 engines!), or just turned out to be quiet by accident.

Regards
Sutripta

[Jeroen]

Originally Posted by Sutripta

The same should hold for conventionally mounted (ie pods from main wing) engines, whether prop or jets. Are the characteristics, and thus what is checked in the certification process, radically different.

I really don't know that much of how the certification process works, but there are certainly differences between various types of aircraft on what gets tested and how.

One of the planes I fly, the Cirrus, was designed to minimize the risk of unintentional stalls through a special wing design and the addition of a ballistic parachute. The FAA felt the design was much better than all conventional means and the Cirrus was exempt from stall testing for its certification.

So certain designs can have an impact on what is tested and how.

Originally Posted by Sutripta

OT - Was the BAE 146 quiet by design (and if so, what elements of the design contributed to it. After all 4 engines!), or just turned out to be quiet by accident.

a

Long before the first one flew it was marketed, amongst others, as being very quiet. So some thinking must have gone into it, maybe they got a bit of luck as well.

It is one of the few airplanes that can handle very steep approaches into airports such as London City. Those steep approaches are usually with engines at idle, so less noise. That is the only thing I can think of, but Im sure there must be more.