On Friday 28 October 2005 02:03, Vassilii Khachaturov wrote: > In a real gravity-fed Cessna, there are 2 aspects relevant to the engine > problems resulting from negative Gs that I was told about by the > instructors. One is the fuel flow (tanks/carb/engine intake manifold) > and the other is the oil flow that has gravity-induced return of the oil > into the sump. If that stops, it's as disastrous as oil leak --- permanent > damage can be done. (As opposed to just engine out due to momentary fuel > absense which goes away as soon as one pulls back up and the gravity is > restored).
This is quite true but it only becomes a problem after a few seconds of sustained *negative* G as opposed to zero G. (Some 152 Aerobats have inverted oil systems to prevent this all together). I have more information on the survivability of engines starved of oil but it's probably not relevant here ;) > As for the clearing the climb path, I was told to do some gentle S-turns > rather than pushing over the nose in order not to screw up the airspeed > and hence the time-to-climb calculations, as well as be less nauseating > for the passengers (of course, if executed in a properly coordinated > matter). We were training in a busy traffic area (EGBE UK) where other aircraft in unexpected places were a regularity. Typically we would make one check before reaching 650' QNH and turning crosswind. The trick to making the check is to leave the trim set to climb and just push forward momentarily while scanning ahead for anything resembling your own aircraft. Typically, aircraft would re-stabilise in its nominal climb in 10 seconds or so - not an issue when climbing for the training circuit. I can quite safely say that while you would have 'your heart in your mouth' as you pushed forward, it was certainly not even a zero-G motion and the engine certainly wouldn't waiver. Also, in low-G manouvers such as a high-AoA entry to an incipient spin or a 0-G pushover where very low positive G (certainly lower than 0.3G) is sustained for maybe 2 to 3 seconds, the engine would behave as in the cruise. Having flown the manouvers during PPL training (not required but none the less useful) I am adamant that the IO-200 will experience no power-loss down to a small fraction of a G even when sustained for several seconds. -- Dave Martin http://museum.bounce-gaming.net _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
