737 de-icing question
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737 de-icing question
The Boeing manual calls for higher V-speeds, takeoff weight reductions and no reduced thrust takeoff if deicing has been done on the 737-200 but does not have these restrictions for the 737-200A.
Why is that?
Why is that?
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de-icing or ANTI-icing? Some a/c that have had thickened fluids applied use things like increased speeds to ensure the fluids flow off during the takeoff roll to avoid problems at rotation/liftoff. Maybe that's part of the story?
Some old text from Boeing:-
“Investigation has shown that both Type I and Type II aircraft ground de-icing/anti-icing fluids cause a transitory lift loss and drag increase. Aerodynamic effects of most of the older generation (1987 and earlier) Type II fluids (most of which are no longer commercially available) were found to be significantly larger than those of Type I fluids. New formulation Type II fluids, developed in 1988, have aerodynamic effects no greater than those of Type I fluids, while providing significantly longer holdover times during which they protect the wing from ice, frost and snow. Evaluation of the effects of both fluids on the performance of all Boeing jet transports indicates that, with the exception of the 737-100 and -200 Non-Advanced for which performance adjustments are recommended, sufficient performance margins are available to offset the effects of the fluids.” Boeing Airliner Oct 1989
Although the newer fluids / aircraft types do not require (recommend) performance adjustment, there is still some performance loss due to the anti-icing fluid – margins are reduced.
Of the data which I saw from several manufactures’ test flights (type II / IV circa 2000), most of the performance loss was judged acceptable. However, IIRC some turboprop manufacturers did make a performance adjustment, but this might have been due to other icing / anti-ice fluid factor.
“Investigation has shown that both Type I and Type II aircraft ground de-icing/anti-icing fluids cause a transitory lift loss and drag increase. Aerodynamic effects of most of the older generation (1987 and earlier) Type II fluids (most of which are no longer commercially available) were found to be significantly larger than those of Type I fluids. New formulation Type II fluids, developed in 1988, have aerodynamic effects no greater than those of Type I fluids, while providing significantly longer holdover times during which they protect the wing from ice, frost and snow. Evaluation of the effects of both fluids on the performance of all Boeing jet transports indicates that, with the exception of the 737-100 and -200 Non-Advanced for which performance adjustments are recommended, sufficient performance margins are available to offset the effects of the fluids.” Boeing Airliner Oct 1989
Although the newer fluids / aircraft types do not require (recommend) performance adjustment, there is still some performance loss due to the anti-icing fluid – margins are reduced.
Of the data which I saw from several manufactures’ test flights (type II / IV circa 2000), most of the performance loss was judged acceptable. However, IIRC some turboprop manufacturers did make a performance adjustment, but this might have been due to other icing / anti-ice fluid factor.
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Looking a little more deeply into this I discoved that there are some wing differences between the 200 and the 200 advanced.
On the 200 advanced, all the slats have two possible extended position. EXT which is a partial extension for flap selections of 1 to 10. At greater than 10 the LED's go to the FULL EXT position. On the earlier non-advanced models, only the outboard slat on each side had the capability of going to full extend position and only with flaps greater than 25°. I woould love to see a picture of this if someone has one.
Apparantly earlier basic 200 models had different Krueger flaps as well in that they did not go as far inboard toward the root of the wing as 200 advanced aircraft. On the 200 advanced, these flaps extend underneath the landing lights at the wing root instead of the earlier gap between the inner portion of the innermost Kreuger and the fuselage.
Can be seen here:
The Boeing 737 Technical Site
On the 200 advanced, all the slats have two possible extended position. EXT which is a partial extension for flap selections of 1 to 10. At greater than 10 the LED's go to the FULL EXT position. On the earlier non-advanced models, only the outboard slat on each side had the capability of going to full extend position and only with flaps greater than 25°. I woould love to see a picture of this if someone has one.
Apparantly earlier basic 200 models had different Krueger flaps as well in that they did not go as far inboard toward the root of the wing as 200 advanced aircraft. On the 200 advanced, these flaps extend underneath the landing lights at the wing root instead of the earlier gap between the inner portion of the innermost Kreuger and the fuselage.
Can be seen here:
The Boeing 737 Technical Site
