Didn't know the Skymaster was certified for aerobatics...

[AuxBatOn]

Depends what you define as "slow". Anything less than 180 degrees a second for me is slow.

It's not about stress on the aircraft. It's about certification. The airplane was not certified to do this. It was likely never flight tested. No need to test it yourself...

[AuxBatOn]

Just to show the importance of certification for the experts, look here: https://www.youtube.com/watch?v=WMG_G9ostt0 fast forward to 1:45 for the interesting part. If you don't flight test an area of the envelope, you cannot know the behavior of the aircraft in that part of the envelope. An aircraft that was designed for exactly this kind of maneuvers did not behave so well. It lead to a limitation of max 1 roll at full deflection.

What is the 337's behavior while rolling? What are its limitations?

[lownslow]

What does the placard say under the registration? Looks like it starts with "Do not" and I hope it ends with something like "do anything dumb in this airplane."

[co-joe]

I still say that the manoeuvre voided the c of a until maintenance performs a detailed inspection and signs off on it in the journey log. Not just while it was being performed. Does an overweight landing only void the c of a as the wheels touch and then everything's ok as long as the legs don't fall off? We only saw one roll. Who's to say the first 10 didn't go so well?

[PilotDAR]

It's about certification. The airplane was not certified to do this. It was likely never flight tested.

It's not about getting in, but getting out, particularly if things go wrong. A well flown roll is hardly stressful on a plane, but a recovery can be if the roll was not well flown. If spinning a plane would make you nervous, then so should rolling it. I've posted this before, to remind viewers that certification testing is done to assure that pilots don't have to be test pilots, if they fly within the box.

[youtube]https://www.youtube.com/watch?v=zjB_q7AIvDo[/youtube]

The spin testing went exactly as planned. I temporarily installed a G meter, so I knew what I was doing TO the plane during recovery. I did 2.5 to 2.8 G's at or near Vne, ten times that day. The number which I found un-nerving, and casual aerobat pilots also might, was that each recovery dive at 2.5 G and near Vne, also peaked at more than 9000 FPM down - in a Caravan.

Those who fly certified planes presumably do so to benefit from the confidence that the aircraft has proven itself during certification testing. So why fly it outside those limitations?

[cgzro]

Just as an aside, interesting things can happen at full aileron deflection. For example some RVs will exhibit a worrysome aileron buffet if you roll them at full aileron and in fact you need to not use full aileron to get maximum rate im some ac. Also some aircraft need substantial rudder to counteract the adverse yaw of full aileron and that can vary as the speed decreases going up and increases comming back down. Non trivial stuff to do safely every single time.

[AirFrame]

For example some RVs will exhibit a worrysome aileron buffet if you roll them at full aileron and in fact you need to not use full aileron to get maximum rate im some ac.

I haven't measured the exact roll rate, but it feels like the RV-6 rolls faster with the ailerons deflected just short of the point where they start to buffet. The buffeting is also speed dependent... At a slower entry speed you can go to full deflection without getting any buffet.

[lownslow]

I still say that the manoeuvre voided the c of a until maintenance performs a detailed inspection and signs off on it in the journey log.

Maybe, but what inspection? I doubt the maintenance manual has an inspection for intentional rolls and figuring out exactly what needs to be done is probably as vague a process as figuring out whether or not it was in any way okay in the first place.

[LousyFisherman]

So next, is it not feasible for an average pilot to do a roll and stay well within the structural envelope?

In a slow rolling plane odds of success would be poor.
Faster rolling much easier better odds.

I'll play the role of average, possibly below average pilot.
I have six hours aerobatics. At the time, 18 months ago I would have been allowed to do solo rolls and loops I do not "fly" the roll, I mechanically execute the appropriate procedure for the plane, in this case a Citabria .

Always at least 2000' feet AGL, my choice would be 4000'
Dip 5 degrees to build speed, 120mph if I recall correctly, fairly quick transition to 5 degrees up.
QUICK co-ordinated FULL rudder, FULL aileron, HOLD until just before level again
Not slam, but QUICK.

I know I wouldn't want to be there, unexpectedly, below 2000 AGL.
Without the training I wouldn't want to be there at all. Too many distractions.

YMMV
LF

[AirFrame]

Is there a chance that the military's version of the 337 was built/certified differently? Does the military even have many small aircraft that aren't aerobatic?

[trampbike]

The lightest aircraft the RCAF owns are the Twin Otter and the Griffon. They're not great at aerobatics.

[AuxBatOn]

Why are we talking about a military 337?!

[rigpiggy]

Because it was built on the same production line as the civvie version with main changes being wing fittings for rocket pods

[AuxBatOn]

The one in the video isn't military and isn't likely built to the same specs as the military version.

[AirFrame]

Why are we talking about a military 337?!

Because: https://en.wikipedia.org/wiki/Cessna_O-2_Skymaster
Just wondered if it was built any differently, because the Wiki page doesn't mention it.

O-2A
Version designed for use in forward air control missions, features ordnance hard points underneath the wings to hold rockets, gun pods or flares.

This strikes me as an application where an aircraft with increased structural strength to support manoeuverability may be an asset.

[rigpiggy]

read a book by an O-2 guy in viet nam. the big diffs were wing hardpoints and obervation doors/skins. Cessna offered to build a tandem version with strengthened wings, but it would take an extra 16-18 months USAF said build it as it was RFN. I do believe the warbirds are run under 337 type cerification.

[PilotDAR]

Adding wing hardpoints and "capacity" there, without increasing the gross weight, does not increase the loads on the main part of the primary structure, it actually reduces it a little ('Kinda why the C 310 and certain other type have tip tanks).

And then there was....



I had a good chat with the pilot who flew it. He said it was a poor performer, and much worse when the rear engine quit!

[rigpiggy]

A quick google search showed a warbird o2 registered as an m337B, so civilian equivalent

[goingnowherefast]

When considering it's military application, we're forgetting that it's a pretty slow aircraft. Going 120kts, you are pretty maneuverable within normal category limits. Can turn around pretty quick at 120kts in a 60* bank.

The 337 didn't need an aerobatic capable structure to maneuver around hills in Vietnam.

[xdriver]

Cessna 337

cessna 337-2 001.jpg (291.79 KiB) Viewed 2039 times