Indian Military Helicopters

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Rakesh
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Re: Indian Military Helicopters

Post by Rakesh »

India is interested in Israeli Systems for its Combat Helicopter Fleet
https://i-hls.com/archives/80424

India is enhancing its combat helicopter fleet. HAL (Hindustan Aeronautics Limited) has received a Request for Proposal (RFP) for 15 Limited Series Light Combat Helicopters (LCH) from the Indian Air Force (IAF) and the Indian Army. This comes close on the heels of HAL receiving RFP for the supply of 83 LCAs (Light Combat Aircraft) just days ago. India has been showing interest in several Israeli systems for this helicopter, namely various pods and Spike anti-tank missiles manufactured by Rafael Advanced Defense Systems. LCH is a 5.5-ton class, combat helicopter designed and developed by HAL. It is powered by two Shakti engines and inherits many technical features of the Advanced Light Helicopter. According to the company’s statement on its website, the features that are unique to LCH are sleek and narrow fuselage, tri-cycle crashworthy landing gear, crashworthy and self-sealing fuel tanks, armor protection and low visibility features which makes the LCH lethal, agile and survivable. The helicopter would have day/night targeting systems for the crew including the Helmet pointed sight and Electro-optical pod consisting of CCD camera/FLIR/Laser Range Finder (LRF)/ Laser Designator(LD). The LCH is fitted with Self Protection Suite consisting of Radar/Laser Missile warning systems and Countermeasures dispensing system. Presently, four technology demonstrators are under flight testing. LCH has the distinction of being the first attack helicopter to land in Forward Bases at Siachen, 5400 m above sea level.
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Re: Indian Military Helicopters

Post by chola »

ramana wrote:

How does Mi-17 V5 compare to which Sikorski helicopter?
Came across this while researching the chini Z-20:
https://www.ainonline.com/aviation-news ... pter-0?amp
The PLAAF eventually acquired 24 Sikorsky S-70C-2s with the enhanced General Electric T700-701A engines. It was reported that the S-70’s performance in the highlands was unmatched, even with the later acquisition by China of Mil Mi-17V5 helicopters from Russia.
The chinis struggled for 30 years trying to reverse-engineer the S-70 even though they have access to and fly lots of Mi-17s. They finally have a few CopyHawks in altitude testing in Tibet.

I think that makes a pretty good case that the Sikorsky is the better aircraft. But the Mi-17 is no slouch since they attempted to get a license to produce that as well (look at my previous posts on the chini-russki JV.)
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Re: Indian Military Helicopters

Post by Singha »

they are not really comparable. the Mi17 has a back ramp permitting vehicles and small artillery to be wheeled in and 2X the passenger capacity of the blackhawk family. the blackhawk cabin is a bare bones box open on both sides and a low floor. half the time I fear people will just fall out, just like the UH1 cabin. all must be hanging on to ropes or strapped in.
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Re: Indian Military Helicopters

Post by Austin »

chola
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Re: Indian Military Helicopters

Post by chola »

^^^ Yes Singha ji, configuration is different but nearly the same size and payload.

They are considered to be equivalents and were in fact debated as equivalents when the US bought Mi-17s for the Afghan military.

http://www.heritage.org/middle-east/rep ... s-taxpayer
The UH-60 Blackhawk is one of the finest helicopters ever to have flown in combat and has served the U.S. military wonderfully in combat operations in Iraq and Afghanistan since 2001. However, the Mi-17 is the best all-around choice for both the Afghans and the American taxpayer.
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Re: Indian Military Helicopters

Post by nachiket »

chola wrote:^^^ Yes Singha ji, configuration is different but nearly the same size and payload.

They are considered to be equivalents and were in fact debated as equivalents when the US bought Mi-17s for the Afghan military.
The US may consider them equivalent but the fact remains that the Mi-17 can carry twice the number of passengers/stretchers and more than twice the internal cargo than the UH-60. The Americans don't have a helicopter which is an exact counterpart of the Mi-17. The UH-60 is lighter and carries less, the CH-47 and CH-53 are much larger. Maybe the old CH-46 Sea Knight is roughly comparable.
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Re: Indian Military Helicopters

Post by deejay »

^^^ Nachiket ji, absolutely agree. I was resisting any reply because of my obvious bias towards Mi 17. Chalo, you said it.
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Re: Indian Military Helicopters

Post by Philip »

How do we resurrect Spike for the LCH when we've just cancelled it for the armed forces in anticipation of a new desi ATGM ?

There is some angst with the IA, etc. about the cancellation of the $ 500 M deal v.urgently needed as we have a shortage of around 68,000 missiles with no war reserves req. for 10 days of intense fighting.The exg.Sov. Konkurs missile do not reportedly have night fighting capability so too Milan 2T.

Bibi N is due to arrive shortly.Perhaps Spike may be rehabilitated like Sov. leaders in the past! If the req. is so huge and replacement of legacy missiles in lakhs to come as well, why couldn't both Spike and the Desi ATGM to come have enough orders and both be acquired?
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Re: Indian Military Helicopters

Post by Yagnasri »

I do not remember you advocating anything other than Natashas sir. :D First time I am reading this. But I agree with you. Spike may be an interim solution at least.
chola
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Re: Indian Military Helicopters

Post by chola »

deejay wrote:^^^ Nachiket ji, absolutely agree. I was resisting any reply because of my obvious bias towards Mi 17. Chalo, you said it.
I beg your pardon, Deejay Saar! I am but a mango reading literature and most of my literature is American with said bias :-?
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Re: Indian Military Helicopters

Post by deejay »

^It is absolutely ok. The UH 60 is a wonderful machine. The Mi 17 beats it in internal volume and load capacity. External load is same for the machine. The Serivce Ceiling for Mi 17 family is better than the brochure figures as personally tested. Also, their VNEs are easily crossed. Though it still won't match the UH 60 in top speed. The Mi 17 is much better in inserting Special Heliborne troops deep inside if the EW suite are assumed to be same.
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Re: Indian Military Helicopters

Post by nachiket »

deejay wrote:Also, their VNEs are easily crossed.
:eek: No point in calling it VNE then :D. The Russians should update the brochures.
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Re: Indian Military Helicopters

Post by Philip »

Top two CEOs of Finnmeccanica found not guilty by the Italian Supreme Court! Evidence found insufficient by the SC.Huge ramifications to the Indian case.ACM Tyagi and his brother accused now out on bail awaiting the next hearing in May..Unless there is concrete new evidence the verdict will stand.Some say forged docs.were used in the framing of evidence and witnesses changing their stories.

The COB has based its entire case based upon the foundation of the Italians case.If that case has collapsed how can the case in India now continue? Was there an in necessary witch hunt against ACM Tyagi and his brother by Indian authorities who may have jumped the gun in prosecuting the accused.
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Re: Indian Military Helicopters

Post by Karthik S »

Maj Surendra Poonia‏Verified account @MajorPoonia
Follow Follow @MajorPoonia
More
1/1 With equipment like this, we don't need an enemy to kill our soldiers
ALH almost ends up severely maiming 4 Special Forces soldiers when the boom broke in republic day practice.
Pray for injured bravehearts
@adgpi @nsitharaman @narendramodi
Really unfortunate, hope the men recover soon and well.
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Re: Indian Military Helicopters

Post by Indranil »

I have been waiting for news since I saw the video a few hours back. Livefist and Manu Pubby are reporting that the men are okay. That is a miracle, at least for the guy who fell from about 30 feet.
Karthik S wrote:
Maj Surendra Poonia‏Verified account @MajorPoonia
Follow Follow @MajorPoonia
More
1/1 With equipment like this, we don't need an enemy to kill our soldiers
ALH almost ends up severely maiming 4 Special Forces soldiers when the boom broke in republic day practice.
Pray for injured bravehearts
@adgpi @nsitharaman @narendramodi
Really unfortunate, hope the men recover soon and well.
I am not on Twitter. But can somebody ask major sahab, why he blames ALH for a boom failure?
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Re: Indian Military Helicopters

Post by deejay »

^Major Punia is a groundsman. He would not that the boom is not ALH.
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Re: Indian Military Helicopters

Post by Indranil »

It would be interesting to know if he corrected himself on being shown the truth. I mean he is wrong on many accounts in one sentence.

ALH aside, the number of men, the event, the outcome!
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Re: Indian Military Helicopters

Post by ks_sachin »

deejay wrote:^Major Punia is a groundsman. He would not that the boom is not ALH.
"groundsman" - that is a new one... never have any of my airforce 'uncles' used this term..
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Re: Indian Military Helicopters

Post by deejay »

ks_sachin wrote:
deejay wrote:^Major Punia is a groundsman. He would not that the boom is not ALH.
"groundsman" - that is a new one... never have any of my airforce 'uncles' used this term..
There is no such term . I was trying to explain a non aviation person in a single word.
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Re: Indian Military Helicopters

Post by Singha »

video here of the alh incident
http://www.ibtimes.co.in/3-indian-army- ... deo-756558

very fortunate he fell on the soft earth not the rajpath. but bone and organ injuries could be severe.
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Re: Indian Military Helicopters

Post by ks_sachin »

deejay wrote:
ks_sachin wrote: "groundsman" - that is a new one... never have any of my airforce 'uncles' used this term..
There is no such term . I was trying to explain a non aviation person in a single word.
I know
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Re: Indian Military Helicopters

Post by ramana »

Here is a picture of the broken boom. Looks brittle fracture. I don't see fatigue crack.Either material strength issue or overloaded.

https://twitter.com/reachanshul/status/ ... 4852197376
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Re: Indian Military Helicopters

Post by Indranil »

Has anybody seen any other video of ALH where three men are on that rope simultaneously from that boom?
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Re: Indian Military Helicopters

Post by tsarkar »

Indranil wrote:But can somebody ask major sahab, why he blames ALH for a boom failure?
Indranil, the boom was part of the ALH airframe as it was bolted on it.

As per International Regulations for Preventing Collisions at Sea 1972 and earlier laws, even if a pole or ladder or net juts out of a ship and strikes another ship or boat causing damage or injury, the ship will be held guilty. It cannot say ladder was an accessory and not part of the ship. Similarly, any accessory mounted on an aircraft will be considered part of the aircraft.

If the AC on a person's car is defective, he will blame the car manufacturer because he sees the car as a complete package and not sum total of accessories and components.
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Re: Indian Military Helicopters

Post by chola »

ramana wrote:Here is a picture of the broken boom. Looks brittle fracture. I don't see fatigue crack.Either material strength issue or overloaded.

https://twitter.com/reachanshul/status/ ... 4852197376
The boom is hollow? Sorry but that makes me wince. I guess it saves weight but how much more would a more solid piece of metal be for a three foot or so boom?
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Re: Indian Military Helicopters

Post by Zynda »

Why don't you calculate it Chola sir? Assume a rectangular cross section of 10 in x 10 in. And a length of 36 inches. So the volume is 10 x 10 x 36 = 3600 in^3.

Consider a hollow section of the above with wall thickness of 1 in. Area of the C/S = (10 x 10) - (8 x 8 ) = 100-64 = 36 sq. in. And the volume = 36 x 36 = 1296 in^3...round it off to 1300 in^3.

Assuming the density is the same...savings = 3600 - 1300 = 2300 units. Pretty substantial I would say.

In fact rarely solid sections are used anymore...most of the sections used are hollow as many of the important area parameters which are important in contributing to rigidity are very near to the area parameters of a solid section with as illustrated above substantial weight differences. Shafts are one of them applications where I have seen solid cross sections being employed.

Ramana saar I would say very likely overload...I guess even in brittle materials there would be fatigue crack stritations. (I gotta verify the last part).
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Re: Indian Military Helicopters

Post by chola »

^^^ Good show, Zynda! I applaud your answer backed up with clear calculations. Too bad we do not have a “thumbs up” smilie here or I would have given you one.
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Re: Indian Military Helicopters

Post by Indranil »

A snap so close to the base can be purely coincidental or a sign of overload.
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Re: Indian Military Helicopters

Post by JayS »

Indranil wrote:A snap so close to the base can be purely coincidental or a sign of overload.
One or more bolt-holes failed, it seems, starting a chain reaction. Bolt holes are locations of stress concentration so it failed at the weakest point.

I think I see a composite part there (black remains still attached to the bolts) which was bolted to a metal part.

Also if it had to fail its more likely it would fail at the base, where the bending load is max for a cantilever. It failed exactly where I was the weakest.
Zynda wrote:Why don't you calculate it Chola sir? Assume a rectangular cross section of 10 in x 10 in. And a length of 36 inches. So the volume is 10 x 10 x 36 = 3600 in^3.

Consider a hollow section of the above with wall thickness of 1 in. Area of the C/S = (10 x 10) - (8 x 8 ) = 100-64 = 36 sq. in. And the volume = 36 x 36 = 1296 in^3...round it off to 1300 in^3.

Assuming the density is the same...savings = 3600 - 1300 = 2300 units. Pretty substantial I would say.

In fact rarely solid sections are used anymore...most of the sections used are hollow as many of the important area parameters which are important in contributing to rigidity are very near to the area parameters of a solid section with as illustrated above substantial weight differences. Shafts are one of them applications where I have seen solid cross sections being employed.

Ramana saar I would say very likely overload...I guess even in brittle materials there would be fatigue crack stritations. (I gotta verify the last part).
The shafts of Jet engine carrying thousands of HP power are hollow and rather thin skinned. :D I suppose only those applications would use solid bars/cylinders where removing material from center is in-economical and/or weight is not a concern. The central portion of material contributes very less to the strength.


Folks, note that, as much as it can be a design fault, it could simply be a freak accident or a rare failure event too. Its not uncommon to have them. No point in blaming someone unless technical enquiry report is out. No design methodology can guarantee 100% failure-proof design.

Pray for wellbeing of the soldiers who fell down. And lets wait for report. Meanwhile OK to discuss technicalities without trying to point fingers.
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Re: Indian Military Helicopters

Post by JayS »

Indranil wrote:Has anybody seen any other video of ALH where three men are on that rope simultaneously from that boom?
https://www.youtube.com/watch?v=bDt2qnlruUo

At one point you will see 3 soldiers on the rope. Also another video I saw from AeroIndia where you can make out that three must be on rope, but doesn't cover the entire rope properly so not posting.
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Re: Indian Military Helicopters

Post by deejay »

Is there a limitation which says less than 3 must be on the rope?
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Re: Indian Military Helicopters

Post by JayS »

deejay wrote:Is there a limitation which says less than 3 must be on the rope?
You would be the best person to answer that, I thought.

Obviously would be some limit, because the system would be designed for certain load. May not be 3 of coarse. I just saw a lot of videos on Heli insertion and it seems the SOP is to have only 2-3 on the rope at a time. The next guy waits for a while many times. This could simply be to avoid collisions though.

For this particular case, I don't think the failure was due to overload. Even in hypothetically we consider that the system was designed for only 2 persons, the FOS would have made sure that it would not fail even with 4-5 persons. Factors of safety in such simple systems is typically high.
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Re: Indian Military Helicopters

Post by deejay »

Then why are we continuously discussing if 3 were on rope or not. It is irrelevant.
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Re: Indian Military Helicopters

Post by ramana »

JayS, I was wondering if the stress guys reviewed the design? Putting bolt holes at the point where the bending moment is the highest for a cantilever seems a design weakness. Also Al unless its high magnesium alloy doesn't have much ductility. If you look at the break surface, I admit we don't have a micrograph, shows its a brittle or non ductile fracture (no shear plane breaks).
From what I learnt very rarely the boom snaps like this. It just broke all across. It must have started at the bolt holes.

BTW nice sized fasteners with locking features.(To me looks like HiLok)
So what happened to all of them? Or just a few are used?

Image

See that yellow coating. That's Zinc Chromate for corrosion protection.

Factor of safety for aircraft systems would be 1.5 with an Ultimate load of double that.

If we know the cross section dimensions and assuming Aluminum material properties we should be able to figure out the ultimate load.
Don't forget the stress concentration factor of those bolt holes.
As it brittle it will apply for normal loads. Not just fatigue loads.
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Re: Indian Military Helicopters

Post by ramana »

Need to look at the mating boom part. Both will tell the story.
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Re: Indian Military Helicopters

Post by Zynda »

I can't make out head or tail about the boom config from the above picture. Is there a picture of the intact boom showing its location on the helicopter? What does the boom carry or support?

I have not looked at the video because I don't want to see the unfortunate incident.

I found these two pictures of soldiers hanging off Dhruv at two different locations.

I remember Dhruv carrying a boom support inside the fuselage just above the side doors for soldiers to deploy quickly.

Image

I am assuming the 2nd picture has the location of the boom which underwent failure earlier today.
Image

I have poor Googling skills...if anyone can post a better picture detailing the boom, its location & how its installed.

Ramana, at least I cannot make out which is top or bottom (or sides) from the twitter picture. And without knowing the config, I cannot determine which side is experiencing tension/compression during bending and thus I would not make comments about the design choices without knowing the full picture. BTW, it is a very common thing to place fastener holes at the end region of cantilever (of course with proper analysis). How else would one transfer load from boom to supporting structure?

If JayS is correct, it could be that one or more bolt holes could have seen fatigue cracks (what is called as Multiple Site Damage) & unfortunately on this day even with a 3 men load (which is a normal operating condition) the load became too much and the cracks spread from hole to hole.
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Re: Indian Military Helicopters

Post by JayS »

Zynda, look carefully. Its easy to figure out top side and bottom. Load pulling down on cantilever. Top side in tention. See top side in picture. Torn off. All bolts missing. Bottom side in compression. So two bolts still there. Lower part didnt fail. A part of boom remained attached. The boom obviously didnt fail. Failure was in the bolted joint. Had not for the lower intact bolts, it would have cleanly detached.

Picture is taken standing on the roof of the heli, next to engine, looking down.

Ramana Sir, obviously it would have been designed/ Reviewed by structural engineers. Production folks cant just make a bolted joint own their own for Helicopter without proper structural design. I cannot say if its good or a bad design based on the location and proximity to base of cantilever. One can always properly design it with enough strenght however close or farther it may be from base.

Also your point about brittle failure is a valid one. I am also thinking how it got such failure. Need more info on material. It definately looks like metal. The joint is metal composite joint, IMO.

Just remembered something I saw in one of the
Tech sessions recently. This is a type of bolted joint failure called "Net tension". Typical for composites. Unusal for metals i feel.
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Re: Indian Military Helicopters

Post by ramana »

JayS, Thanks.

In my career I have seen many foolish things. I saw a lock wire hole in a web. That was the weakest link.

Maybe initial design was reviewed but final configuration might have been given cursory looksee.

Many factors could have cause the root cause to be unmasked.

Also one factor forgotten is sudden loading of the cable. But the cable will stretch reducing the DLF ( dynamic Load factor instead of 2 to maybe 1.75)


Yes hope they post the other side picture will ask the Twitter poster.
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Re: Indian Military Helicopters

Post by ramana »

https://twitter.com/reachanshul/status/ ... 1610090496


Good picture shows boom configuration. It's cantilever beam attached to helicopter.
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Re: Indian Military Helicopters

Post by shiv »

This accident is a classic example of how new and unexpected things turn up when a machine goes into regular use. Now that part will be inspected for stress failure in all the Dhruvs in service.
Locked