Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 8/21/84; site idi.UUCP Path: utzoo!watmath!clyde!burl!idi!kiessig From: kiessig@idi.UUCP (Rick Kiessig) Newsgroups: net.aviation Subject: Re: Flat Spins Message-ID: <268@idi.UUCP> Date: Wed, 14-Nov-84 01:25:55 EST Article-I.D.: idi.268 Posted: Wed Nov 14 01:25:55 1984 Date-Received: Thu, 15-Nov-84 02:19:26 EST References: <946@opus.UUCP> Distribution: net Organization: Intelligent Decisions, Inc., Saratoga, CA Lines: 110 From "Aerobatics" by Neil Williams: "If we look at the flat spin from inside a Zlin 526, we will see that it can be entered from any position which will permit a normal spin. If we first establish a normal spin to the right, and wait for it to stablise, we will note that it is faster than the left hand spin [the prop on the Zlin goes to the right -- RK], with the nose a little higher, about 50 to 60 degrees, and we have about 5 to 10 degrees of bank to the right. If we now apply full left aileron, still keeping the stick back, the nose will come up to about 45 to 40 degrees, with a faster rotation and less bank. If we now apply full power, the nose comes up dramatically to about 10 degrees below the horizon, and we really start to rotate, but the vertical decent has now slowed. To complete the requirements for the flat spin, still with full power and full aileron, push the stick fully forward! By now the nose will be on or above the horizon in a fully developed flat spin in the best sense of the term. The reason for this forward stick is thought to be that it blanks off the fin and rudder, which are now moving so fast that they are tending to slow the spin. "To recover, as one would expect, one merely reverses the operation. Stick back, throttle closed, ailerons neutral, and when the aircraft stablises full left rudder and stick forward. It will take up to 2.5 turns to stop, and it will feel longer, so don't panic; just give the recovery action time to work." End of quote You can also enter a flat spin directly, like from the top of a slow outside loop, which sounds more like what happened to the RC plane referred to in the original article. You can also do this manuever inverted. The lomcovak: There are five different kinds. The "Main Lomcovak", "Cap Lomcovak", "Positive Conic Lomcovak", "Negative Conic Lomcovak" and another one which is initiated from sliding knife flight in a 45 degree climb. This last one is interesting to watch because the plane will actually go upwards, backwards! The conics make the plane look like a kids toy top spinning around - positive is with the prop staying relatively still, and negative is for the tail staying still. Cap and Main are too hard to describe without drawing a picture. All of them are gyroscopic manuevers, though; made possible by the gyroscopic forces of the engine and prop. As such, the throttle is a critical element of control. Again, from "Aerobatics": "The 'main' lomcovak is entered from a climb which is slightly over the vertical, the level speed before the climb having been as described above [biplane: max. straight and level speed, monoplane: 85% of max. S&L speed -- RK]. If the propeller turns anticlockwise as seem from the cockpit, the inverted flick roll [i.e. snap roll -- RK] is initiated with left rudder, and stick forward and to the right. At this point the flightpath precesses owing to engine/propeller gyroscopic forces, and the aeroplane reaches a state where all the rotation is about the lateral axis in a forwards direction, this axis being vertical with respect the the earth. "A this point one has the option of leaving full power on and continuing with the 'main' lomcovak, with the lateral axis itself precessing after the first turn until it is again horizontal; alternatively, one can use the throttle to acheive a 'cap' lomcovak. In the first case, if the entry has been fast in terms of control application, it can produce three complete turns; the last being a forward loop on the spot with nil airspeed. It can also cause damage to the aircraft, so I personally restrict it to two turns, by entering the figure more gently. One can also finish up in an inadvertant tailslide, with fully deflected controls. "By leaving full power on, a steady roll around the longitudinal axis of the aeroplane can be maintained: this is not due to the ailerons because airspeed is almost zero. In the case of the 'cap' lomcovak, the intention is to make a forward loop of 360 deg. with the lateral axis vertical to the earth; therefore the engine is used smoothly as an extra aerodynamic control to prevent any further roll around the 'A' axis once the 'B' axis is perpendicular. Since the rotational force for the complete manoeuvre comes from the engine, throttling down will slow the pitch rate almost to zero, and this should be reached after one complete rotation. "In our aircraft as described above the right wing will be towards the ground. The stick is pulled fully back and left full rudder is applied: this initiates a sideslip to the right, just enough so that when the rudder is reversed and power applied, one exits in the same manner as from a stall turn to the right. If this rudder reversal technique is not used, the aeroplane will roll onto its back and sink out of control." End of quote Well, you get the idea. I'd be interested in hearing from anyone who has a chance to play with any of these moves using RC equipment. -- Rick Kiessig {decvax, ucbvax}!sun!idi!kiessig {akgua, allegra, amd, burl, cbosgd, decwrl, dual, ihnp4}!idi!kiessig Phone: 408-996-2399