Karan M wrote:JayS wrote:
Karan, I am questioning the wisdom in designing and qualifying the rope system for only two persons at a time (which is what Indranil is pointing to) precisely considering the real life limitations on maintaining such SOP in strictest sense, especially in the actual war scenarios. There are multiple photos/videos which shows Dhruv has seen more than 2 persons on the rope in past. As I understand the separation in soldiers on rope is followed to avoid collisions. In my limited google search I could not find any reference to "design limits of insertion system putting limits on number of people on rope".
Typically, the design would have followed SQR which means the item either flowed directly from the SQR or was a result of any other SQR driven requirement, either way, it would be signed off by all stakeholders. I suspect it was not an issue all these days, because of the SOP, of using a second attachment point. Somewhere, in operations, it was discovered that SOP caused a time delay or was inconvenient and hence it was changed, precipitating this incident. Of course, this is all speculation at this point and the IA will find the real reason working with HAL.
To get back to my original point, If you have an engine power rating specified which means an engine of some weight, and so forth, and that means a bracket of some weight/rating, the designer would take the decision and services would not be so interested. Its the designers issue after all, but in an issue like deciding how many people on a hoist, there is no way HAL would take that decision on its own. That information has to come from the user.Having an SOP of two soldiers on rope by Indian Army does not/should not imply "HAL designed the system only for 2 persons".
It typically would, because one thing I have realized about our designers & institutions is they are very risk averse about overpromising given past issues and hence will follow the SQR to the T.
Take the Tejas having R60 vs R73E for instance.If HAL indeed do this then the wisdom behind this design decision is very much questionable. I would think its rather in favor of HAL not to point out that the boom was only qualified for 2 people. Because that's an absurd thing to do on the designer's side. Why would anyone design it only for 2 persons when designing it for even 4 or 6 is not going to add to the weight any significantly while making the design far more robust..?
Its hardly absurd, its sticking to the mandate very precisely and then what happens thereafter is another story altogether.
Wherever the designers decide to "out think" the SQR there is a tradeoff elsewhere and getting that cleared means more paperwork, more permissions from the services, more cribbing through out the design chain and your own people, easier to stick to a narrow mandate and be done with it.
Which is what makes the requirements projection so crucial.
Karan, SQR only specifies certain requirement and not how it is to be achieved. That's a designer's decision. Also lets not compare this with something like an engine bracket. Engine bracket design has far more involved design methodology. This particular bolted joint we are talking about can be easily designed with hand calculations based on simple conservative formulae. There is hardly any performance penalty by increasing load from say 200kg to 400kg. Its not going to increase weight by much, perhaps couple of kilos more on the metal component which failed.
Anyways, I have been trying to get the thing cleared that its highly unlikely to be a design issue, even if we consider its only designed for 2 person's load. I posted above, other references that show that's a valid design choice with some possible constraints forcing such decision and I stand corrected on that point. But at the same time I have noted that the weak links are the small metal links/clips, attachment points of rope to boom etc. Rope itself is pretty strong and I am very sure that the metal/composite components such as the boom itself are also far more conservatively designed.