steves@tektools.UUCP (steve shellans) (08/30/85)
A couple of years ago I was doing a lot of spins in a 152 (for fun).
The trouble is that the 152 is spin resistant, and half the time it
would just go into a spiral dive instead of a true spin. At the time
I was using standard technique -- power at idle, ailerons neutral,
ease back on the yoke, as the plane is about to stall apply full rudder.
Then a read about a cross-control spin entry technique in a magazine.
I decided to try it. (I *strongly* recommend that you do NOT try this.)
Here's how it goes: Full power, high nose-up angle (about 45 degress seems
right. As all pilots know, the plane will try to yaw left due to p-factor.
No right rudder is used -- instead, right *aileron* is used to counteract
the yaw. Rudder remains neutral and, of course, the ball is over to
the right.
Airspeed bleeds off to the point where a stall is imminent. Then, while
still holding full power and right aileron, apply full left rudder. Spin
entry is instantaneous and the rate of rotation is considerably higher
than I was accustomed to. It was great. Even after I pulled power off,
the high spin rate continued.
But then, a funny thing happened on the way to the ground. After about
4-5 turns, I applied standard spin recovery technique. But instead of
recovering, it went into another spin mode which was nearly a flat spin.
The nose was pointed down about 30 degrees below the horizon and the
plane was still spinning. Recovery was difficult.
I thought about it for a couple of days and decided to try it again to
see if it was a fluke. No fluke. Identical behavior.
There are 2 reasons I am posting this to the net:
- With the recent rash of spin messages on the net, I wanted to alert
you to the potential danger of this particular type of spin entry.
- Does anyone know the aerodynamics of what happened? Has anyone else
been in a flat spin in a 152? If so, what recovery technique did you use?
Steve Shellans
[ihnp4,allegra,decvax] !tektronix!tektools!steveslmiller@ucla-cs.UUCP (09/02/85)
Spin recovery in the 152--several years ago the NTSB conducted a study of the spin properties of the 150/152. One of their conclusions was that the usual recovery technique, full forward stick, could lead to problems because the elevator blocked air flow to the rudder. They recommended a a very specific technique that involved moving the stick only to neutral, not all the way forward. The complete recovery method is a bit more complex, and I don't remember the details. Anyone spinning a 150/152 should speak with a knowledgeable instructor, and review the NTSB recommendations on the 150/152. L. Miller
bob@ulose.UUCP ( Bob Bismuth ) (09/03/85)
> > I thought about it for a couple of days and decided to try it again to > see if it was a fluke. No fluke. Identical behavior. > Well, you'd never have caught me trying it a second time! I think I would have searched out a good acro CFI and talked it through with him/her to understand what happened. Maybe I'm chicken, but one crash can spoil your whole day. If you are really interested in cross-controlled spins, flat spins and the like, get a good acro CFI and a plane that's certified in the Unlimited Acro category. Also, get a proper 'chute and make sure that you actually can get out of the craft you use when practising. You are right to caution people about such spins. For details on spin aerodynamics there has been a series of very good articles in the EAA Sport Aviation publication running since the beginning of this year. All types of cross-controlled, flat and inverted spins are described, along with the dangers and recover techniques for each type. There was also an interesting short about a flat spin in a Luscombe 8, of particular interest to me since most of my recent time is in one. It seems the owner decided to take a friend (pilot) up to try some spins. At 4000 ft AGL, he spun it. Trouble was the nose didn't drop below the horizon. The plane turned slowly and quietly and no amount of power would break the spin. Realizing what was going on, the owner calmly opened the left door (since there is no "headwind' in a flat spin) and started climbing out over the lift strut. Half way over the strut the nose fell through the horizon. He quickly got back in and recovered from a 'normal' spin. What went wrong for him? Weight and balance. When they landed they discovered the plane had so many uneven coats of paint and un-logged modifications that the cg was 1" too far aft. That'll do it do you everytime - moral of the story: if you're going to spin it, make sure of your cg first, then make sure the plane is certified for spins at your proposed takeoff weight and balance configuration/distribution. Above all, get some instruction first for any type of spin. What amazes me is that the guy had the presence of mind to climb out. I know the door/strut configuration very well and am not sure I could have managed it with the plane sitting on the ground and the engine turned off. -- bob (decvax!ulose!bob)
fredc@bmcg.UUCP (Fred Cordes) (09/03/85)
I soloed in a Cessna 150 and used full (40 degree) flaps for all 3 landings. I came in high the first 2 times and confidently slipped the plane to get down, he then pointed out that if a stall occurred while the plane was crossed up in a slip, it would immediately roll inverted into a spin with no chance for recovery. He said cross control spin entries were possible for gliders too when approaching a landing, Isuppose because of the slow control response. I did get some spin training in a 152 after I got my license and I enjoyed it but I don't think the 152 is the plane to experiment with- it isn't designed to spin routinely, I was told. Fred Cordes
fredc@bmcg.UUCP (Fred Cordes) (09/03/85)
orry about that last. The main point is that 40 degres flaps on a C150 supposedly blocks the tailplane and can cause loss of control authority. If this is combined with slow approach speed (close to stall) and cross control for a slip, a disastorous spin entry can occur, with an inverted roll entry. Fred Cordes
dmmartindale@watcgl.UUCP (Dave Martindale) (09/05/85)
I found another article about the Beggs (hands-off-the-stick) spin recovery technique. It points out that this technique is intended for certain types of aerobatic airplanes only, and has not been tested for others. In particular, it quoted someone from NASA who suggested that the typical high-wing spinnable Cessna would take significantly longer (4 turns instead of 1 or so) to recover from a spin using the Beggs technique instead of the standard wheel-forward recovery method.
dbp@dataio.UUCP (Dave Pellerin) (09/05/85)
> (...insert long excerpt about cross-controlled spins and stuff here...) > I had the priveledge of training for my private with an instructor who believed in spins during training, not just so you knew how to get out of them, but to demonstrate the concept of 'reverse command'. He taught two ways to enter a spin; the first was the climb, stall, chop power, and stomp on rudder method. The second method was the same up to the point of stall, but just before the stall, the yoke was turned completely to the right. The effect of this was that the left wing stalled early, while the right wing kept flying. The drop into a spin was quite dramatic even with minimal left rudder. In that particular airplane, another student had been too eager in his spin recovery, and when he shoved the stick forward, a full can of oil that had been left sitting behind the seats (dumb!) shot up and smashed through the rear window (penzoil from heaven!). - Dave Pellerin -
ron@brl-tgr.ARPA (Ron Natalie <ron>) (09/07/85)
> I soloed in a Cessna 150 and used full (40 degree) flaps for all 3 landings. > I came in high the first 2 times and confidently slipped the plane to get down, > he then pointed out that if a stall occurred while the plane was crossed up > in a slip, it would immediately roll inverted into a spin with no chance for > recovery. He said cross control spin entries were possible for gliders too > when approaching a landing, Isuppose because of the slow control response. > > I did get some spin training in a 152 after I got my license and I enjoyed it > but I don't think the 152 is the plane to experiment with- it isn't > designed to spin routinely, I was told. > > Fred Cordes 152's slip alright with full flaps, the operating handbook doesn't place a limitation on this, it's 172 that you shouldn't consider slipping with lots of flaps. I've never had any desire to do something to a plane that the manufacturer has told me was unsafe. -Ron
jeq@laidbak.UUCP (Jonathan E. Quist) (09/08/85)
In article <1841@bmcg.UUCP> fredc@bmcg.UUCP (Fred Cordes) writes: >The main point is that 40 degres flaps on a C150 >supposedly blocks the tailplane and can cause loss of control authority. This is also true of 172's. I recall reading that this is the reason that newer 150's, 152's and 172's have only 30 degrees of flaps available. I believe it was the 172-N that first had the restricted flaps; I'm pretty sure I've flown that version both ways. I just purchased a 172-B (1961 model). At the end my first flight in the beast, I pulled flaps as usual (with the exception that it has manual flaps, not electric) on approach. I was a little high on short final, so I pulled the last 10 degrees (to 40). The immediate reaction was that the tail kicked off to one side. I had no desire to experiment with rudder authority at 150' AGL, so I went back to 30 degrees and suddenly everything straightened right out... The Moral: *Always* learn the craft's behavior at altitude. (Full flaps stalls was the one thing I hadn't tried.) Jonathan E. Quist ihnp4!laidbak!jeq
brad@gcc-bill.ARPA (Brad Parker) (09/08/85)
In article <1841@bmcg.UUCP> fredc@bmcg.UUCP (Fred Cordes) writes: >orry about that last. The main point is that 40 degres flaps on a C150 >supposedly blocks the tailplane and can cause loss of control authority. Hummmm... This might explain why some of the 152's I've flown lately only have 30 degrees of flaps (an ECO? ;-). I could have sworn I'd flown 150's with a full 40 degrees.... -- J Bradford Parker uucp: seismo!harvard!gcc-bill!brad "She said you know how to spell AUDACIOUSLY? I could tell I was in love... You want to go to heaven? or would you rather not be saved?" - Lloyd Coal
ark@alice.UucP (Andrew Koenig) (09/09/85)
>>Sorry about that last. The main point is that 40 degres flaps on a C150 >>supposedly blocks the tailplane and can cause loss of control authority. >Hummmm... This might explain why some of the 152's I've flown lately only >have 30 degrees of flaps (an ECO? ;-). I could have sworn I'd flown 150's with >a full 40 degrees.... I have never seen a 152 with 40 degrees of flaps. Nor have I seen anything in the 150 flight handbook that mentions any problem with using full flaps. However, a 150 with full flaps does not climb terribly well; I wouldn't be surprised if that was the real reason for reducing the maximum flap extension. For instance, I was once doing some landings at Caldwell airport (NJ) when I heard a 172 call in and get clearance for a tough-and-go. After the 172 left the ground again, the pilot discovered he couldn't get the flaps up. There were four on board. There were a few rather tense minutes as I circled over the airport at pattern altitude+800 and the pilot nursed the 172 around the pattern at treetop level. This was at night, by the way.