Re: Scie chimiche- dibattito- Ma scusate...
Inviato da Teba il 23/10/2008 11:54:57
Citazione:
Identici come propulsione intendi?
perchè, di solito, quando uno fa notare la presenza di una scia dietro un aereo mentre in un altro che vola a fianco non se ne vede traccia, vengono presentate ricerche come quelle di Schumann e Busen ( qui)
ed è vero che la formazione di contrails è correlata alla propulsione dei motori, ma bisogna anche notare che quel test, ad esempio, è stato effettuato a quote superiori ai 10000 mt.
"A contrail was observed to form during ascent first behind the A340 at 7:28:40, at flight level 333 hft. The B707 continued to ascend nearby without a contrail. About 50 s later, at altitude of about 337 hft, a contrail formed also behind the B707 at 7:29:30. The contrails were observed to be forming very suddenly and persisted thereafter.
During descent from flight level 350 hft, the contrails disappeared first behind the B707 and disappeared shortly thereafter behind the A340. The contrails occurred again, apparently when entering colder or more humid air, and finally disappeared behind the B707 at flight level 344 hft at 7:40:00 (Fig. 3) and shortly thereafter behind the A340 at flight level 342 hft at 7:40:39. These times were deduced after the fliight from the video observations with an uncertainty of less than 5 s. As a curiosity, we note that during descent, for about 20 s, the B707 formed contrails only behind the two engines on the left wing while no contrails were visible for the right wing engines, possibly because of different power settings on the two wings.
E le differenze di quota per la formazione di contrail nei due differenti tipi di aerei non sono nell'ordine di 1000 -2000 m, ma risultano nell'ordine di 80 -200 m (a seconda se il volo è in fase di ascesa, o in fase di volo orizzonatale in quota sopra i 10000 m), infatti :
"The observed altitude difference in contrail formation conditions
of the two aircraft is about 80 m during ascent. This value is smaller than expected for normal cruise conditions in a standard atmosphere
(about 200 m) because of the reduced power settings and because of a rather large temperature lapse rate encountered during ascent
in the present experiment."
ciao
...ma ti scervellerai nel chiederti come mai aerei identici alla stessa altitudine uno fa scie persistenti e l'altro non ha scia.
Identici come propulsione intendi?
perchè, di solito, quando uno fa notare la presenza di una scia dietro un aereo mentre in un altro che vola a fianco non se ne vede traccia, vengono presentate ricerche come quelle di Schumann e Busen ( qui)
ed è vero che la formazione di contrails è correlata alla propulsione dei motori, ma bisogna anche notare che quel test, ad esempio, è stato effettuato a quote superiori ai 10000 mt.
"A contrail was observed to form during ascent first behind the A340 at 7:28:40, at flight level 333 hft. The B707 continued to ascend nearby without a contrail. About 50 s later, at altitude of about 337 hft, a contrail formed also behind the B707 at 7:29:30. The contrails were observed to be forming very suddenly and persisted thereafter.
During descent from flight level 350 hft, the contrails disappeared first behind the B707 and disappeared shortly thereafter behind the A340. The contrails occurred again, apparently when entering colder or more humid air, and finally disappeared behind the B707 at flight level 344 hft at 7:40:00 (Fig. 3) and shortly thereafter behind the A340 at flight level 342 hft at 7:40:39. These times were deduced after the fliight from the video observations with an uncertainty of less than 5 s. As a curiosity, we note that during descent, for about 20 s, the B707 formed contrails only behind the two engines on the left wing while no contrails were visible for the right wing engines, possibly because of different power settings on the two wings.
E le differenze di quota per la formazione di contrail nei due differenti tipi di aerei non sono nell'ordine di 1000 -2000 m, ma risultano nell'ordine di 80 -200 m (a seconda se il volo è in fase di ascesa, o in fase di volo orizzonatale in quota sopra i 10000 m), infatti :
"The observed altitude difference in contrail formation conditions
of the two aircraft is about 80 m during ascent. This value is smaller than expected for normal cruise conditions in a standard atmosphere
(about 200 m) because of the reduced power settings and because of a rather large temperature lapse rate encountered during ascent
in the present experiment."
ciao
Messaggio orinale: https://old.luogocomune.net/site/newbb/viewtopic.php?forum=61&topic_id=2976&post_id=128762