I'm dating myself, but Cessna advertising for the T-210 when they first introduced the aircraft to the general public was centered on a "pitch" that said something like "have you ever pulled a contrail........." Dennis Murphy ----- Original Message ----- From: "W Wilson" <wlw-jr@att.net> To: <AIRLINE@LISTSERV.CUNY.EDU> Sent: Sunday, December 30, 2001 3:59 PM Subject: Re: Contrails > Excellent, I hope you were toasty warm in the cabin. I still have yet to > witness trails from piston a/c except from footage of WWII B-17/29s > .......Yes, the Doctor Killers are smooth flying machines. > > Walter > DCA > > ----- Original Message ----- > From: "Dennis Murphy" <dmurphy4@houston.rr.com> > To: <AIRLINE@LISTSERV.CUNY.EDU> > > > > Way back when.......... > > > > I've pulled contrails with my Cessna T-210 (circa 1974) over Colorado & > > Kansas in the winter. My Bonanza A36TC would do the same. I don't > remember > > what altitude, but I do remember it was lower than FL250 (maximum > > "certified" ceiling on both aircraft.) For what's worth, the Bonanza was > > more "fun" to fly......... > > > > Dennis Murphy > > > > ----- Original Message ----- > > From: "W Wilson" <wlw-jr@att.net> > > To: <AIRLINE@LISTSERV.CUNY.EDU> > > Sent: Saturday, December 29, 2001 10:05 PM > > Subject: Re: Contrails > > > > > > > Richard, > > > Here is a message I left about a month ago on the ComAirScan messge > > > board...with a few changes. > > > > > > Depending on the temperature and humidity, contrails will form starting > at > > > around > > > FL310 to FL350 (definitely not carved in stone.) . In summer, they may > > not > > > form at all. In the northern part > > > of the US, contrails on a cooler day, may be around FL280 or lower, but > > > while it can > > > be cold enough for a contrail, there may not be enough moisture in the > > air. > > > Also, except for military aircraft that operate with fuel additives to > > > prevent contrails, a Learjet can leave a contrail as a 747. Also in the > > > Arctic, you may have seen photos of Twin Otters and > > > C-130s leaving trails from start-up, to taxi, thru takeoff. Contrails > form > > > from the hot exhaust rapidly expanding as it hits the colder > > air...remember > > > physics... > > > as air expands, it cools...if it cools to the dewpoint it > > > condenses...thus a trail of moisture is formed. (in this case, due to > the > > > extremely cold temps...the vapor sublimates directly into ice crystals) > > > > > > To answer your Qs. Yes...there can be a narrow band of altitude where > > > contrails will form...depending on temperature and dewpoint. > > > > > > Walter > > > DCA > > > > > > ----- Original Message ----- > > > From: "Richard A Whitenight" <rum.runner@juno.com> > > > To: <AIRLINE@LISTSERV.CUNY.EDU> > > > Sent: Saturday, December 29, 2001 20:58 > > > Subject: Contrails > > > > > > > > > > Anyone who watches the skies sees the contrails emitting from a jet > > which > > > > is obviously in rather cold air <grin>. Why is it that normally only > > see > > > > contrails in a narrow band of cold air? Is there a high and low > > altitude > > > > where contrails don't form, or is it strictly dependent on the > > > > temperature of and/or moisture in the air. > > > > > > > > > >