Unintentional XC
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I think those that are saying the manufacturers are right in accepting low crosswind values are wrong,
if Thursday was a completely calm day with temperatures at -10 then they should certainly be certifying it on other days, it is SENSIBLE figures they should be aiming at, values given should at least be a guide and I would be very surprised if during the certification there not opportunities to demonstrate crosswinds greater than 12kts, whilst it would not be the ONLY factor in buying an aircraft, if I was buying I would be questioning why such a low figure and wondering just how strong the undercarriage is. The Bulldogs at 35kts is higher than really needed and I would not suggest that manufacturers should go out of their way to get high figures, but realistic ones should be achieved, 20 probably being one that should be easily managed in the time available.
Clearly you have no idea what the Demonstrated X-Wind means. Would you like them to certify it on everyday of the week because you didn't think Thursday was sufficient?
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Demonstrated as stated is just that but I do not for one moment think that is realistically the case.
It is surprising how many 15 18 kt days there are
What happens if the aircraft is tested on a 25 kt day is that the figure the pilot puts in the book? I doubt it!
There will no doubt be a discussion and I am sure a lower figure would be selected depending on how tricky the aircraft was at 25kts.
The overriding consideration will be a fairly low timed PPL who does not fly that much while not selecting a figure which makes buyers think there is something wrong with the aircraft.
15kts will probably be used as a bench mark. If its tricky in wind the aircraft will be set lower if its good in wind a few kts higher!
Also into consideration will be the target market and experience of the pilots who are likely to fly the aircraft
Pace
It is surprising how many 15 18 kt days there are
What happens if the aircraft is tested on a 25 kt day is that the figure the pilot puts in the book? I doubt it!
There will no doubt be a discussion and I am sure a lower figure would be selected depending on how tricky the aircraft was at 25kts.
The overriding consideration will be a fairly low timed PPL who does not fly that much while not selecting a figure which makes buyers think there is something wrong with the aircraft.
15kts will probably be used as a bench mark. If its tricky in wind the aircraft will be set lower if its good in wind a few kts higher!
Also into consideration will be the target market and experience of the pilots who are likely to fly the aircraft
Pace
Last edited by Pace; 6th Feb 2013 at 10:19.
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It was blowing a gale here the other day when I was at the club and we were talking about x wind limits etc. I mooted the point that say in the case of the Warrior which has a demonstrated limit of 17kts; although everyone is confident they could handle more than that, if there was a prang of some sort would not the insurance hawks say 'Well the weather at that time was 19kts across so you were flying out of limits therefore no pay out.' ?
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As Aluminium Persuader says demonstrated is not a limit which could be used against an insurance claim.
MTOW is a Limit and a proved overweight takeoff would mean a way out for the insurance.
One thing I am not sure of and no body has clarified is how realistically they come to a demonstrated figure?
I am sure its not the wind of the day the test is done as that could vary from 0 to 30 kts or above.
There must be a set procedure for arriving at a figure! My guess is its probably something along the lines I indicated in my last post but I do not know for sure?
Does anyone know how demonstrated is worked out?
Pace
MTOW is a Limit and a proved overweight takeoff would mean a way out for the insurance.
One thing I am not sure of and no body has clarified is how realistically they come to a demonstrated figure?
I am sure its not the wind of the day the test is done as that could vary from 0 to 30 kts or above.
There must be a set procedure for arriving at a figure! My guess is its probably something along the lines I indicated in my last post but I do not know for sure?
Does anyone know how demonstrated is worked out?
Pace
Last edited by Pace; 6th Feb 2013 at 22:53.
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You would have thought they could work out absolute x wind limits on a computer these days. They can work everything else out on one.
I don't think there's even a demonstrated limit in the 172 POH, if I remember the wording correctly it's something like '15mph which the average pilot should be able to manage.'
I don't think there's even a demonstrated limit in the 172 POH, if I remember the wording correctly it's something like '15mph which the average pilot should be able to manage.'
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thing, foxmouth, etc.
I think you probably have an incorrect view of what manufacturers seek to achieve when certifying and marketing a general purpose aircraft.
Most punters are looking for speed, range, useful load, slick instruments, and a bit of style (note massive success of Cirrus).
Most manufacturers are looking to, meet certification requirements, have a manufacturing cost that allows them to make money and not set landmines to step on and get sued.
Given the certification requirement for crosswind component is a minimum number (i.e. they must positively demonstrate that the average joe can land in a crosswind of 0.2Vso) and almost no one seriously evaluates an aircraft on that number, why would they sweat it to go for a big number.
Now an aircraft marketed as a 'get in and out of the shortest, wildest, boulder strewn mountain strip with radical cross wind and turbulence' may well benefit from a massive maximum cross wind component and obviously rugged gear, but this is marketing as there is no certification requirement for how smooth or rough the landing surface can be.
I think you probably have an incorrect view of what manufacturers seek to achieve when certifying and marketing a general purpose aircraft.
Most punters are looking for speed, range, useful load, slick instruments, and a bit of style (note massive success of Cirrus).
Most manufacturers are looking to, meet certification requirements, have a manufacturing cost that allows them to make money and not set landmines to step on and get sued.
Given the certification requirement for crosswind component is a minimum number (i.e. they must positively demonstrate that the average joe can land in a crosswind of 0.2Vso) and almost no one seriously evaluates an aircraft on that number, why would they sweat it to go for a big number.
Now an aircraft marketed as a 'get in and out of the shortest, wildest, boulder strewn mountain strip with radical cross wind and turbulence' may well benefit from a massive maximum cross wind component and obviously rugged gear, but this is marketing as there is no certification requirement for how smooth or rough the landing surface can be.
Well, that may be so, but I'm sure I heard of an aircraft (? AT3) where 11 knots really was the crosswind limit where the tail ran out of authority. Perhaps I'm maligning the AT3, in which case I apologise to its manufacturers, but I remember reading about a flying school which really wished it had bought something else, because they lost so much flying time on that basis.
