732 Takeoff Flaps
Whatever you do, if your runways are less than 2500 metres, do NOT get suckered in to the wing/flap modification that is marketed for this old beast.
Although it is not particularly expensive, it totally ruins a good airframe.
It was created specifically for a very long runway/high elevation situation - like Mexico City - to overcome climb limitations. It works best at Flap 1 or 2 and I think it offers an intermediate setting at about 7 for situations where 5 or 10 is not optimum (but I have forgotten the details of this).
On runways less than about 2000 metres it is more likely that accelerate-stop will be the performance driver. Between 2000 and 2500 metres optimum take-off weight usually becomes a juggling act between field limits and climb limits.
The modified wing won't help here, as V1 for any given weight/flap is much the same with or without the modifications. Distance to reach V1 is basically a function of thrust versus weight and for a given weight that distance wouldn't vary much even with NO wings! The modified wing/flap may marginally improve acceleration (by getting the weight off the wheels a bit sooner), but it would be so marginal that it would not be worth the expense. Bigger engines - like dash 17s - are the only cure.
The AFM will give you all the info you need to manually calculate speeds etc, but one of the after-market performance providers will do it quicker and probably more accurately. At a cost, but what is your time worth?
Also they have all the survey data, so when the Feds come calling to ask how you derive your numbers, it is easier to pass the buck. I certainly would not be making up my own speed cards by the pidooma method.
Although it is not particularly expensive, it totally ruins a good airframe.
It was created specifically for a very long runway/high elevation situation - like Mexico City - to overcome climb limitations. It works best at Flap 1 or 2 and I think it offers an intermediate setting at about 7 for situations where 5 or 10 is not optimum (but I have forgotten the details of this).
On runways less than about 2000 metres it is more likely that accelerate-stop will be the performance driver. Between 2000 and 2500 metres optimum take-off weight usually becomes a juggling act between field limits and climb limits.
The modified wing won't help here, as V1 for any given weight/flap is much the same with or without the modifications. Distance to reach V1 is basically a function of thrust versus weight and for a given weight that distance wouldn't vary much even with NO wings! The modified wing/flap may marginally improve acceleration (by getting the weight off the wheels a bit sooner), but it would be so marginal that it would not be worth the expense. Bigger engines - like dash 17s - are the only cure.
The AFM will give you all the info you need to manually calculate speeds etc, but one of the after-market performance providers will do it quicker and probably more accurately. At a cost, but what is your time worth?
Also they have all the survey data, so when the Feds come calling to ask how you derive your numbers, it is easier to pass the buck. I certainly would not be making up my own speed cards by the pidooma method.
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John, don't you think that an aircraft which was in one configuration 30 years ago may be in a different on now? My point was that just because 30 years ago a given airplane with a certain configuration couldn't take off heavy weight at flaps 25 doesn't mean it isn't able to today at 30*.
@Mach
The flap mods I spoke of don't apply to the 732 I'm working with. Our performance for this and other aircraft I work with are always obtained from a very reputable engineering and performance firm I've worked with before, but speed tables are always in house.
Thanks for the reply though, helpful in trying to shed light on this for myself.
@Mach
The flap mods I spoke of don't apply to the 732 I'm working with. Our performance for this and other aircraft I work with are always obtained from a very reputable engineering and performance firm I've worked with before, but speed tables are always in house.
Thanks for the reply though, helpful in trying to shed light on this for myself.
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don't you think that an aircraft which was in one configuration 30 years ago may be in a different on now
Absolutely. However, to an engineer, configuration means configuration control (as an ongoing process). Your post wasn't clear as to your intent ?
I suggest, though, that your concern still revolves around AFM certification processes and who pays - an OEM just isn't interested in being a benign and benevolent institution - it's purpose is to make lotsa dollars. You want/need something out of the ordinary, then be prepared to fork out lotsa dollars for the paperwork/mod/whatever.
Absolutely. However, to an engineer, configuration means configuration control (as an ongoing process). Your post wasn't clear as to your intent ?
I suggest, though, that your concern still revolves around AFM certification processes and who pays - an OEM just isn't interested in being a benign and benevolent institution - it's purpose is to make lotsa dollars. You want/need something out of the ordinary, then be prepared to fork out lotsa dollars for the paperwork/mod/whatever.
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I guess I could have worded that a little clearer, the point I was trying to make was that if you couldn't meet climb requirements 30 years ago with -7s slung on the airplane it would have nothing to do with what the airplane can to today.
I agree with your second paragraph that this is a classic case of needing to throw more money at the problem. What struck me as odd, though, is that this is the only type I've worked with which has this issue. On other types the information was always available without the need to purchase additional items.
I agree with your second paragraph that this is a classic case of needing to throw more money at the problem. What struck me as odd, though, is that this is the only type I've worked with which has this issue. On other types the information was always available without the need to purchase additional items.
Moderator
On other types the information was always available without the need to purchase additional items.
.. and that comes back to OEM discretion -
(a) required stuff IN - CHECK
(b) optional stuff likely to make us lotsa dollars IN - CHECK
(c) stuff we decided not to include PAY LOTSA DOLLARS - IN - CHECK
No reason why one OEM on one model shouldn't come up with a different compromise documentation solution to the next ...
.. and that comes back to OEM discretion -
(a) required stuff IN - CHECK
(b) optional stuff likely to make us lotsa dollars IN - CHECK
(c) stuff we decided not to include PAY LOTSA DOLLARS - IN - CHECK
No reason why one OEM on one model shouldn't come up with a different compromise documentation solution to the next ...
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Thanks for the replies, wasn't saying there was or wasn't a reason, was saying I didn't know if there was or wasn't and was hoping to get information on the matter. For that I thank you.
