UK SAR 2013 privatisation: the new thread
A welcome surprise Etudiant - I am far more used to abuse on this thread
Join Date: Sep 2003
Location: uk
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
Also, re: BS, the MAUM of the S-92 you posted is incorrect
One man's blunt is another man's truthful - all depends where you are standing - I have apologised in the past when I have actually insulted someone
Join Date: Sep 2003
Location: uk
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by [email protected]
Don't fly it, don't have an RFM so blame the internet - perhaps 26,500 lbs is correct - the figures were after all just for illustration about disc loading and downwash.
One man's blunt is another man's truthful - all depends where you are standing - I have apologised in the past when I have actually insulted someone
One man's blunt is another man's truthful - all depends where you are standing - I have apologised in the past when I have actually insulted someone
Aren't they all civilian SAR pilots now? Much of my criticism at the time was slightly misdirected due to more organisational ethos concerns. I'm sure there are still good and bad in the Bristow setup.
Again, blame t'internet Even the Leonardo website says 8.3 or 8.6T - 8.3T is as close as to 18,300 lbs as make little difference
The high downwash in the hover is explained by dividing the rotor disc swept area by the AUM of the aircraft to give disc loading in lbs/sqft
For the previous examples, 189 and 92 come out at just over 10 lbs/sq ft compared to the Sea King at 7 lbs/sq ft.
The downwash of the Sea King could be problematic in light winds so it is no wonder the newer helos have issues.
Back to the Wessex for coastal and inland SAR 56 ft rotor, 13,600 bs MTOW, 5.5 lbs/ sq ft disc loading
For the previous examples, 189 and 92 come out at just over 10 lbs/sq ft compared to the Sea King at 7 lbs/sq ft.
The downwash of the Sea King could be problematic in light winds so it is no wonder the newer helos have issues.
Back to the Wessex for coastal and inland SAR 56 ft rotor, 13,600 bs MTOW, 5.5 lbs/ sq ft disc loading
And the 139 comes out the best - 15000 lbs (approx without supplemental increase to 7000Kg), disc 54' 8" - disc loading 6.37 lbs/sq ft.
It certainly seems clear from a downwash point of view that the 139 is the best option from the Leonardo stable for coastal SAR - oh wait, isn't that what was used when the 189s weren't available?
I like the 169 from a size perspective but it comes in at 9.5 lbs/sq ft - however, being less than 2/3 of the mass of the 189 it would have far less downdraught.
It certainly seems clear from a downwash point of view that the 139 is the best option from the Leonardo stable for coastal SAR - oh wait, isn't that what was used when the 189s weren't available?
I like the 169 from a size perspective but it comes in at 9.5 lbs/sq ft - however, being less than 2/3 of the mass of the 189 it would have far less downdraught.
Using rotor diameter 48' 7", MTOW of 16,535 lbs the disc area is 1850 sq ft and the disc loading 8.9 lbs/sq ft
Not the entire story I suspect since the different blade tip and root designs along with the effect of the fuselage shape will have an effect on the working area under the aircraft. This subject was raised at the ICAR Air Commission a few years ago. Some makers had mapped the downwash under certain aircraft but I don't think we got any further with it since the science had never been done for most types. I am happy to work under the intense downwash of the new types since it is the same power that is keeping me safe in the air.
Most of the tip design is to improve forward speed - hence the much higher Vne and cruise speed of the modern aircraft compared to Sea King etc. The Carson blades would have given another 25 kts of speed to the Sea King without changing the downwash.
You can have the extra power to give great OEI performance for safety without the horrendous downwash, you just make the rotors longer but that isn't the fashion amongst designers who like to make the overall aircraft more compact (shorter tailboom for example) to increase the useful space in the cabin.
You don't work much in the water under the aircraft I am guessing Jim?
You can have the extra power to give great OEI performance for safety without the horrendous downwash, you just make the rotors longer but that isn't the fashion amongst designers who like to make the overall aircraft more compact (shorter tailboom for example) to increase the useful space in the cabin.
You don't work much in the water under the aircraft I am guessing Jim?
Second episode tonight, all mountain work, and every other word seemed to be downdraught. Modern helicopter design isn't focussed on what SAR needs.
Originally Posted by [email protected]
... ...
You don't work much in the water under the aircraft I am guessing Jim?
You don't work much in the water under the aircraft I am guessing Jim?
Where downwash is a problem for us is on steep ground, narrow ridges, and avalanche-prone terrain. One can train MRT to deal with working under heavy downwash but the problem remains of persons in distress, and other members of the public, who have no comprehension of the forces involved.
So, given that the purpose of a SAR helicopter is to rescue people from difficult and dangerous situations - will we see a different choice of aircraft for the next contract or will it be more of the same?
Will any manufacturer actually design a SAR-specific helicopter rather than sticking a winch on the side of their offshore model?
Will any manufacturer actually design a SAR-specific helicopter rather than sticking a winch on the side of their offshore model?
Originally Posted by [email protected]
Will any manufacturer actually design a SAR-specific helicopter rather than sticking a winch on the side of their offshore model?
Originally Posted by [email protected]
So, given that the purpose of a SAR helicopter is to rescue people from difficult and dangerous situations - will we see a different choice of aircraft for the next contract or will it be more of the same?
EASA Mountain HEMS? Non, merci.
Within the scope of the current spec one could see H215. H175? 525? ??? What else?
Smaller, faster? Faster: no such thing. Eh ... AW139? Well, fine until the day you are 150nm offshore with IMC at your destination and no space to do proper work on your casualty.
Originally Posted by [email protected]
Will any manufacturer actually design a SAR-specific helicopter rather than sticking a winch on the side of their offshore model?