I was under impression for sometime that the rear wheel is just gonna stick out straight, but looking at the pics, the rear wheel has a pneumatic lever to pull it up, but I don't see any significant space on the tail to pull the rear wheel in. Is it just going to stick to the tail on bottom side and be outside horizantally during flight compared to vertical position while landing or hovering??? Any gyan wud be greatly appreciated !!!
No bhai, that is not a pneumatic lever for pulling it up. Its called a shock strut, and comprises the oleo.
The exposed metal that you see is the length of the oleo stroke..that is how much it can move up (its called a fluid spring), displace hydraulic fluid or both hydraulic fluid and air for a oleo pneumatic system and absorb shock. The length of that oleo stroke (also called vertical axle travel) means that its designed to take real punishment while landing. i.e.absorb plenty of kinetic energy. That is due to the higher crashworthiness requirements for an attack helicopter.
The vertical axle travel required is estimated based on what is the permissible landing load factor (also known as reaction factor). And it should be able to take the limit loads without any permissible deformation..that limit load will be decided based on what is the worst case in which the pilot lands operationally. Multiply it by a factor of 1.5 and you have your ultimate load and that is the load at which the landing gear should still not fail, but if it suffers a permanent set, its considered alright.
What one cannot tell is the oleo's internal construction and whether its a single stage/two stage/mixing type or separator type oleo design. Could well be a single stage to keep it simple and cheap. OTOH, two stage oleos provide varying spring characteristic and are useful for operation if the LCH needs to taxi on rough airfields. If not, and if it only needs to land, the single stage is sufficient.
All in all, a simple robust landing gear design but the length of the stroke made it clear that it was designed to take a really heavy landing.
And its going to be in that position during flight. No retraction is required. Its more complicated to have a retraction mechanism with the actuators, back up system in case it fails to come back out and space is required if its to be pulled into the fuselage, plus you need doors for that which means added hinges and actuators. For weight constrained designs, every kg of weight removed is a performance gain, so its not needed. All that additional effort and you'll get a miniscule reduction in RCS or drag.
These are all mandatory requirements for certification so the performance of the landing gear would've been tested extensively on ground rigs, with drop tests and other tests that certify its usage.