[shortbread]

It's sad to see this project was scrapped after so much effort and expense. While the accident and resulting fatalities was terrible news, not persevering with the project did not benefit anyone. A low cost turbo prop capable of ferrying passengers/goods will have a lot of scope in India, especially servicing rural communities. I hope there is light at the end of the tunnel.

Starting after nearly a seven-year gap, the development of the first indigenous passenger and transport plane, Saras, is firmly back on track. The 7000-kg aircraft is now being tested by the pilots of the Indian Air Force and has made two successful test flights this year.

Production is expected to start in 2022. Saras is expected to cost Rs. 45 crore -- cheaper than what India currently pays. A comparable Dornier plane costs Rs. 60 crore.

The development of Saras, which began 18 years ago, was stopped in 2009 after it crashed during a test flight and two pilots died. Work started again in 2016 at Bengaluru's National Aerospace Laboratories.

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.

"The Saras we have flown now is in fact better than the earlier prototype. There have been several design improvements which NAL as the designer has incorporated in this aircraft, said Air Vice Marshall Sandeep Singh.

Union Science Minister Harsh Vardhan said the project was dumped by the previous government, even though the Directorate General of Civil Aviation had "exonerated the aircraft from any design flaw or poor-quality production". No effort was made to revive the project, he said.

The Saras Mk 2 will be ideal for a variety of applications -- like aerial search, survey, disaster management, border patrol, coast guard, ambulance and other community services. It would also be useful to establish commuter connectivity as air taxi and executive transport under the Udaan scheme, the minister added.

Hindustan Aeronautics Limited will be the production agency for the military version of Saras, while the production of civil version will be given to a private player, officials of the NAL said. India needs 120-160 aircraft -- civil and military - over the next 10 years.

According to NAL, the aircraft available in the international market are of 1970s technology, such as Beechcraft 19000D, Dornier-228 and Embraer EMB 110. They have higher fuel consumption, lower speed, unpressurised cabin and high operating cost. They are also unsuitable for operations from hot and high-altitude airfields.

21
COMMENTSIn comparison, the upgraded Saras Mk2 has considerable drag and weight reduction with unique features like high cruise speed, lower fuel consumption, short landing and take-off distance and low cabin noise. It is also operable from high and hot airfield and the cabin is pressurized, the officials said.

https://www.youtube.com/watch?v=llNNz5dtw5I

https://www.ndtv.com/india-news/a-cl...-plane-1828360

[SmartCat]

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



But NAL Saras has propeller behind the engine.



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

[V.Narayan]

Originally Posted by smartcat

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

But NAL Saras has propeller behind the engine.

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

A few theoretical advantages but no practical ones. This configuration may have been adopted to justify why the NAL will spend XXX crores and 18 years re-inventing the wheel instead of doing a decent license production of a foreign design and then over the years pursue a step by step improvement. Our scientists especially in the defense aerospace sector must have sold this idea to keep themselves gainfully employed. In fact the aerodynamics of two pusher props mounted on the tail are not as well researched as the traditional design of wing mounted turbo-props. Those props cannot but impose air turbulence conditions on the tail. What that does to a T-tail is to be seriously though through too. We try to be special by off beat designs that don't really contribute much but add to the risk. In aerospace we always try to sprint before we can walk which is why even today - Tejas, Sitara, Saras et al - we are trying to crawl let alone walk. And this after tens of thousands of crores and a life time of design and politics. sorry for the rant.

On the flip side the current defence minister is a highly competent person and it is possible that work may actually move instead of falling prey to politicking scientists and revolving door bureaucrats.

I don't see how they need only 20 test flights. 50 would be more realistic.

[sandeepmdas]

Me no tech guy, but the pusher props are notorious for their noise. The beautiful and capable Piaggio Avanti uses this type of configuration. The aircraft was universally panned for its noise signature and Piaggio had to address it seriously. In fact, they launched the new version highlighting this factor :

https://www.youtube.com/watch?v=9MM1fmBpP-Y

[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) Agree with your opinion that we should have started with something conventional though. Regarding the effect of the pusher props to the T tail, a point to note may be that the SARAS has sizable ventral fins. I am not sure how much it mitigates the adverse aerodynamic effects of the props on the T tail. I agree with your estimate on the test flights. I think for an unconventional design like this, they would need even more than 50. I too hope they develop it and put it in to production.
Another unrelated point; I have heard that the Dornier 328 is under licensed production by HAL. They were planning (perhaps they are already) to build more of this vintage airplane due to the delays of the SARAS program.

[Sutripta]

Originally Posted by smartcat

But NAL Saras has propeller behind the engine.

OT - Take a quick look at images of the Kitty Hawk, and decide the direction in which it flew/ flies.

Regards
Sutripta

[Aiel]

Originally Posted by MinivanDriver

Dornier 328

They are manufacturing the Dornier 228, and not the 328.

[Jeroen]

Originally Posted by Sutripta

OT - Take a quick look at images of the Kitty Hawk, and decide the direction in which it flew/ flies.

Quite a few planes of that very early era had a so called pusher configuration. Not quite sure what all the consideration were at the time.

Aerodynamics was still in its early days. So it was probably down to very practical mechanical considerations.

Pusher configurations are still used today, mostly on relatively small aircraft, such as drones and also many ultralights use it. One of the consideration is that having the propellor behind the pilot mean he or she is less likely to loose and arm or a leg.

They were in use well into world war 1, until they figured out how to shoot a machine gun through a rotating propellor!

There are some aerodynamically advantages apperently. In fact, it is said these configuration are more stable, especially during take off as no rudder input is required. On a traditional engine configuration the propwash causes swirling airstreams around the airframe creating a rotating force that needs compensating.

But I think overall the few advantages there might be are offset by all the disadvantages.

Jeroen

[Sutripta]

^^^
In case of the Kitty Hawk, there is also the control surface in front, which looks like a tailfin.

Well, one advantage I can think of is if one were to convert from prop to jet - (Tunnan)!

T Tails are normally not preferred.Why?

Regards
Sutripta

[V.Narayan]

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.

Originally Posted by Sutripta

OT - Take a quick look at images of the Kitty Hawk, and decide the direction in which it flew/ flies.

Originally Posted by Jeroen

Quite a few planes of that very early era had a so called pusher configuration. Not quite sure what all the consideration were at the time. Aerodynamics was still in its early days. So it was probably down to very practical mechanical considerations.

Early aircraft especially in the first decade 1903 to 1913 often had canard planes in the front as with the aerodynamic knowledge of the time canards (or tailplanes in the nose) offered greater control authority for turns and climbs than having the tailplane in its (now) traditional position in the rear. With this canard configuration a pusher prop was a natural outcome.

Pushers have one or two advantages - the wing cuts through undisturbed air - hence better lift, drag. The improvement is in low single digit percentages. Also the sucking effect of the pusher prop smoothens out the airflow over the skin of the whole aircraft in front. It leads to less breakup and micro turbulences in the boundary layer. Boundary layer is the layer of air skimming over the aircraft's skin. Its smoothness or otherwise has effect on drag.

On the flip side pusher engines needed extra plumbing for their own cooling; the Saras configuration of two pusher props on either side of the aft fuselage is so rare it has been tried only once in the last 40 to 50 years by Embraer (the famous Brazilian OEM) and then given up as being too complex. The FAA cautioned Embraer that this unique tail set up will require significant extra testing for flight safety certification.

It is interesting that the certification has been moved from DGCA to CEMILAC. The latter is the military aviation body. More efficient and hassle free and with a more 'lets get the job done' approach. But like all military aviation regulators in most countries safety while important shares space with many other priorities. So Saras is likely to come in first as a military utility/recce platform and maybe later as a civilian transporter. It remains my belief that the vanity and politics to prove themselves as different has led the NAL down the path of a design many others have looked at and said nay not worth it. NAL has attempted to design 3 aircraft thus far and 3 drones. All after years remain 'experimental' and still born. It is in the national interests that we have an NAL that does aeronautical research like the old Soviet TsAGI's. But it is also in the national interests that NAL after 4 decades produces something. They have to their credit contributed as a supplier of designs to the ISRO space programme. For the sake of the nation and the million of tax payer money invested I wish NAL success.


Saras. That is a very crowded aft section. Crowded plumbing and wiring, airflows getting mixed and not enough space. As Marcel Dassault once said to fly right a plane must look right.


The Embraer CBA-123. Abandoned after two prototypes were tested.

[sandeepmdas]

Originally Posted by Sutripta

^^^

T Tails are normally not preferred.Why?

Regards
Sutripta

T Tails induce irrecoverable deep stalls. In most such aircraft, a stick pusher is incorporated in the cockpit interface, which may either warn the pilot about the angle of attack or automatically pushes the elevator control to mitigate.

[Jeroen]

Originally Posted by sandeepmdas

T Tails induce irrecoverable deep stalls. In most such aircraft, a stick pusher is incorporated in the cockpit interface, which may either warn the pilot about the angle of attack or automatically pushes the elevator control to mitigate.

To be precise, they can induce deep stalls. If properly flown they should not. To add stick pushers and or stick shakers are not necessarily the exclusive domain of T tails. Many modern aircraft have them.

Apparently, the T tail is still the second most common design after the conventional arrangement. There are a number of variants on the T tail.

Jeroen

[V.Narayan]

Getting the aircraft first into military use and allowing it time to mature and then opening it up for civilian regional routes is the right way to go. I suspect the Govt. will not be able to force private carriers to buy the aircraft like could have been done before 1989. Fundamental technical skills are not lacking in NAL or HAL or DRDO. What, in my opinion, is lacking is the higher leadership formed by people who understand that something as vast and deep as our nation's aeronautical design and development competence is built step by step and not with one giant leap - and this includes our IAS brethren. You have to painfully build the process of concept-testing-design-testing-development-testing and then prototype-testing capabilities and body of tribal knowledge. The fault lies not just with these three outfits but also with the IAF who have not always extended themselves as an operator to help mature the products even where they worked - HF-24 Marut, HAL Rudra/Dhruv are two examples. Fortunately with the Army's support Rudra and Dhruv are moving ahead on a good track. The Chinese, Brazilian's and us started at roughly the same spot in the mid 1950s, in fact we were ahead, but now both those nations are far ahead. The successes at ISRO and the Navy give me hope. The day projects such as Tejas, Sitara, Saras fully mature into mass service will be a happy day for me.

[Jeroen]

Originally Posted by V.Narayan

Getting the aircraft first into military use and allowing it time to mature and then opening it up for civilian regional routes is the right way to go. .

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?

My brother in law is chief engineer at one of the big (western) aviation/avionics companies. Most of his programs are military\intelligence variants built upon various existing airframes. Simply put, he adds a bunch of electronics to a bare airframe more or less.

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.

Only when the plane is fully accepted by the customer, usually the military and or intelligence agencies, they convert and run, if need be, additional programs to get it into whatever military certification regime is necessary and or applicable. Of course, in reality it is not a full serial process, they will look at military requirements too, but the civilian process appears to be leading initially.

It might be very different of course for planes that will only have a military role, such as fighters. I assume only military requirements and whatever certification regime applies would come into play. That is untill the aircraft is taken out of service, ends up in a museum, some enthusiast get their hands on it and put it back in the air, which at that time will require some form of civil certification.

Jeroen

[amitk26]

Originally Posted by V.Narayan

A few theoretical advantages but no practical ones. This configuration may have been adopted to justify why the NAL will spend XXX crores and 18 years re-inventing the wheel instead of doing a decent license production of a foreign design and then over the years pursue a step by step improvement. Our scientists especially in the defense aerospace sector must have sold this idea to keep themselves gainfully employed.

HAL already has production license of Dornier 228 ( 19 seater) and they have produced and sold 125+ DO 228 to military users.And DO-228 is in use for military ( SAR / Transport) in Angloa, Bangladesh .Malawi , Germany , Finland , India, Thailand , Mauritius , Seychelles etc. As per wiki some 63 Airlines use DO-228 for civilian use.
Originally Dornier was from a German company which no longer exists HAL is now the sole manufacturer ( also recently TATA for newer avatar Dornier 228N)

Recently HAL obtained certification of DO-228 for civilian use in domestic market and will be able to sell it to domestic civilian operators under UDAN scheme. The problem with DO-228 is that it's cabin is not pressurized so the experience will be little unnerving for civilian flyers.

https://www.thehindubusinessline.com...le10000625.ece

DO 228 is also 19 seater but with wing mounted turbo prop.

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.

So it's obvious that something new which has theoretical advantage has to be tried for all the improvements.
if suppose nothing new is tried out how exactly they can improve upon what existed since 30 years.
I think it is not right to deride this effort.