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 L-2 Stall/Spin Characteristics

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RyanShort1
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PostSubject: L-2 Stall/Spin Characteristics   Wed May 13, 2009 5:16 pm

It's fairly well known that the L-2s were grounded for a time by the USAAF after some stall/spin accidents. Now having flown an L-2 myself, I don't think I've ever gotten close to a spin, but do any of the other pilots on the board have an opinion?

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PostSubject: Re: L-2 Stall/Spin Characteristics   Sat Jun 20, 2009 7:53 pm

Ryan,
I've had my L-2 for 6 years. They are extremely docile airplanes. The issues the Army had were a series of fatal crashes while landing. Specifically while making circling approaches and the pilots getting too slow and stalling while in turns. The L-2 stalls abruptly and, if banked over, wants to go onto its back. I've tried this a few times at altitude.

The L-2 has very little washout compared to a L3- or L-4 so is a little less well behaved when stalling. The trade-off is that an L-2 will walk away from it's L-bird siblings. Cruise is about 15 mph faster.

Flown properly, the L-2 offers little in the way of surprises. Before stalling there is plenty of warning. The plane wants a lot of aft stick, there's a bit of buffetting and the controls get very mushy. Finally it gets eerily silent in the cabin. At this point you're probably about 1mph away from stalling.
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PostSubject: Re: L-2 Stall/Spin Characteristics   Sat Jun 20, 2009 11:20 pm

That just about jives with what I've experienced. I think it's more a matter of training. Is suspect that the Army (or the instructors weren't training to the aircraft, but to the techniques and that, properly used, the L-2 could've been even better than the L-4 in combat.

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PostSubject: Re: L-2 Stall/Spin Characteristics   Sun Jun 21, 2009 11:46 am

As much as it pains me to admit it, the low-speed handling of the Cub likely did make it better suited for the needs of the Army ground forces although I would argue that the advent of the L-2M with spoilers negated any Cub advantage. With spoilers deployed, the L-2 can fly amazingly steep approaches. Landing roll is nearly non-existent.

Combat effectiveness of L-birds probably wouldn't see much difference between them. They're all essentially the same -- just variations on a theme. Take-off; orbit, observe and report; land.

I think the L-2 was done in by instructors/students hopping from one aircraft to another and believing they all handled the same. Pity as I think the L-2 is the better of the three.
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PostSubject: Re: L-2 Stall/Spin Characteristics   Fri Jul 02, 2010 7:16 pm

Howdy, I hope you don't mind me butting in here.

In addition to the L-2 being grounded, the L-3 was grounded as well. This occurred at Fort Sill in July 1943 and was due to a disproportionately high number of fatal stall-spin accidents in those aircraft over the preceeding months. After July 19, 1943, all use of these aircraft was discontinued for primary training purposes in the army's artillery pilot training program.

First, one must consider that artillery pilot training was nothing like civilian pilot training, so the aircraft were flown near the edge of the envelope on a regular basis at low altitudes. A 1000 foot traffic pattern altitude was unheard of. 500 was even excessive. It was the nature of the business, and low altitude stall-spin fatalities killed more of these students than any other reason. I happen to have in my possession numerous documents relating to the army light plane program corroborating this. I also have a number of original training posters used at Fort Sill depicting mangled L-Birds with captions sternly admonishing students that "doing this leads to this". Many of them depict the L-2. Gruesome but effective teaching aids.

Also consider that the L-2, L-3 and L-4 were being used for the first 60 hours of training and most of the accidents occurred when the students were flying solo, so inexperience was the primary cause, and the students were pushed hard since primary training only lasted 9-10 weeks. Very few accidents occurred with an instructor on board, by the way. The instructors at Fort Sill were all hand-picked, highly experienced pilots who were from civilian backgrounds. They were not "by the book" Air Corps trained pilots who were relatively inexperienced in light aircraft as they were at other liaison pilot schools such as LaMesa. The Fort Sill instructors were specifically chosen for their hard earned experience in flying light planes under difficult and challenging circumstances, so the blame cannot be laid on them jumping from one aircraft to another and not appreciating the subtle differences between types. These guys could fly anything including a barn door.

Say what you will about the L-2, but compared to the L-4 it is not as well-behaved when it comes to stalls and spins, especially in a turn, especially if cross-controlled. In addition, the slower and more stable spoiler-equipped L-2M did not appear in service until 7 months after the earlier L-2 models were all grounded and ousted from the training program at Fort Sill and other training facilities. Don't get me wrong, I love the L-2 and would buy one in a minute if the opportunity presented itself, and in the hands of a skilled pilot it is a fine airplane. For the novice pilot, however, the L-4 (J-3) is a more forgiving airplane and WWII military accident statistics show this without a doubt.

Now, its flying qualities weren't the only reason the L-2 was grounded by Fort Sill and ousted from the liaison pilot training program, but that's all most people remember. In addition, the factory was having trouble meeting its delivery obligations and that just added to the negative image in the eyes of the Army. On top of that, for reasons of supply, maintenance and training efficiency, there was a movement afoot within the War Department to reduce the types of aircraft in use and to focus onone or two standard types that best met requirements. The L-5 was unanimosly preferred by the using arms and the L-4 ran a close second. All the other L-Birds were soon relegated to "limited standard" or "obsolete" classification and contracts for them were either cancelled or shortened prior to 1944.

Before concluding my history lesson, it is interesting to note that in December 1941, a light plane evaluation board at Fort Knox issued a report on all the civilian light aircraft it had evaluated for possible military use. Piper, Stinson, Aeronca, Taylor, Interstate, and Rearwin had all submitted aircraft for evaluation during the preceeding months. The report stated that the Rearwin and Taylorcraft were "completely unsuited for liaison work". The fact that the models evaluated were side-by-side and not tandem seating versions was part of the reasoning, but other factors were considered as well, including slow-flight handling charasteristics. Ironically, despite this sharp criticism, politics -- and the Piper Corporation in particular -- helped the Taylor Aircraft Company win a substantil contract anyway.

So, in a rather large nutshell, "that's the rest of the story" as Paul Harvey would have said.


Last edited by Sentinel Club on Fri Jul 02, 2010 8:18 pm; edited 7 times in total (Reason for editing : Incomplete. Browser has crashed 3-4 times while writing this.)
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PostSubject: Re: L-2 Stall/Spin Characteristics   Fri Sep 10, 2010 8:15 am

Actually, there were a number of different missions. The one you mention is the observation role, but there were also supply, rescue, evacuation, insertion, and liaison missions. The terrain, altitude, and landing areas could make a significant impact on which aircraft was better for the job.

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PostSubject: Re: L-2 Stall/Spin Characteristics   Sun Oct 31, 2010 9:46 am

Sentinel Club wrote:
Howdy, I hope you don't mind me butting in here.

In addition to the L-2 being grounded, the L-3 was grounded as well. This occurred at Fort Sill in July 1943 and was due to a disproportionately high number of fatal stall-spin accidents in those aircraft over the preceeding months. After July 19, 1943, all use of these aircraft was discontinued for primary training purposes in the army's artillery pilot training program.

First, one must consider that artillery pilot training was nothing like civilian pilot training, so the aircraft were flown near the edge of the envelope on a regular basis at low altitudes. A 1000 foot traffic pattern altitude was unheard of. 500 was even excessive. It was the nature of the business, and low altitude stall-spin fatalities killed more of these students than any other reason. I happen to have in my possession numerous documents relating to the army light plane program corroborating this. I also have a number of original training posters used at Fort Sill depicting mangled L-Birds with captions sternly admonishing students that "doing this leads to this". Many of them depict the L-2. Gruesome but effective teaching aids.

Also consider that the L-2, L-3 and L-4 were being used for the first 60 hours of training and most of the accidents occurred when the students were flying solo, so inexperience was the primary cause, and the students were pushed hard since primary training only lasted 9-10 weeks. Very few accidents occurred with an instructor on board, by the way. The instructors at Fort Sill were all hand-picked, highly experienced pilots who were from civilian backgrounds. They were not "by the book" Air Corps trained pilots who were relatively inexperienced in light aircraft as they were at other liaison pilot schools such as LaMesa. The Fort Sill instructors were specifically chosen for their hard earned experience in flying light planes under difficult and challenging circumstances, so the blame cannot be laid on them jumping from one aircraft to another and not appreciating the subtle differences between types. These guys could fly anything including a barn door.

Say what you will about the L-2, but compared to the L-4 it is not as well-behaved when it comes to stalls and spins, especially in a turn, especially if cross-controlled. In addition, the slower and more stable spoiler-equipped L-2M did not appear in service until 7 months after the earlier L-2 models were all grounded and ousted from the training program at Fort Sill and other training facilities. Don't get me wrong, I love the L-2 and would buy one in a minute if the opportunity presented itself, and in the hands of a skilled pilot it is a fine airplane. For the novice pilot, however, the L-4 (J-3) is a more forgiving airplane and WWII military accident statistics show this without a doubt.

Now, its flying qualities weren't the only reason the L-2 was grounded by Fort Sill and ousted from the liaison pilot training program, but that's all most people remember. In addition, the factory was having trouble meeting its delivery obligations and that just added to the negative image in the eyes of the Army. On top of that, for reasons of supply, maintenance and training efficiency, there was a movement afoot within the War Department to reduce the types of aircraft in use and to focus onone or two standard types that best met requirements. The L-5 was unanimosly preferred by the using arms and the L-4 ran a close second. All the other L-Birds were soon relegated to "limited standard" or "obsolete" classification and contracts for them were either cancelled or shortened prior to 1944.

Before concluding my history lesson, it is interesting to note that in December 1941, a light plane evaluation board at Fort Knox issued a report on all the civilian light aircraft it had evaluated for possible military use. Piper, Stinson, Aeronca, Taylor, Interstate, and Rearwin had all submitted aircraft for evaluation during the preceeding months. The report stated that the Rearwin and Taylorcraft were "completely unsuited for liaison work". The fact that the models evaluated were side-by-side and not tandem seating versions was part of the reasoning, but other factors were considered as well, including slow-flight handling charasteristics. Ironically, despite this sharp criticism, politics -- and the Piper Corporation in particular -- helped the Taylor Aircraft Company win a substantil contract anyway.

So, in a rather large nutshell, "that's the rest of the story" as Paul Harvey would have said.

I would ask the following questions:
- Was Ft Sill using L-2s, L-3s, and L-4s simultaneously? Clearly a lot of these airplanes were produced and they had to be going somewhere. Considering the performance/handling differences between the three, a high probability of accidents would exist if students were being bounced among the three types while at a very early stage of training. While each type is pretty docile, they are still distinctly different.

- for all its perceived bad qualities, a lot of L-2s were produced, particularly the L-2M.

Despite its reputation, IMO, the L-2M is a far better airplane than both the L-3 and L-4. That said, having owned both an L2 and L-3, as well as having flown an L-4 and a fair number of Cubs, there is little difference between them, vis-a-vis basic traits. None have anything remotely approaching a vicious nature. In fact, all three are pretty docile. It's mostly a matter of trade-offs. The L-2 traded some low-speed handling qualities for higher cruise speed. The L-4 went the opposite -- going for very stable low-speed handling at the expense of top speed. The L-3 falls in the middle of the two.

The side-by-side seaters being unsuitable comment made me laugh a bit. The RAF seemed to do just fine with their 50hp license-built Taylorcraft Model C's and later added big engines (130hp) and flaps the same design -- resulting in the Taylorcraft Auster series (Mk I thru V, and postwar Mk 6 thru 9) which remained in use into the 1960s.
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