Warbird Aerobatics

[A2C]

Hey Folks:

The discussion on the L-29 was interesting and thought provoking. Everybody's coments were good. With that said what about warbird aerobatics? The photo of the A-26 doing a loop was noteworthy. Since the loop was being done with a ring spar modified aircraft do the recommendations to not do aerobatics no longer apply?

Please feel free to discuss other maneuvers such as those done with the L-29 in the previous discussion as well.

Thanks,

[mlenoch]

Highly recommended with caveats.
VL

[Vessbot]

I highly doubt the A-26 in that picture is doing a loop. You can do a roll and get away with a lot less G's than even non-aerobatic planes are rated for, but a loop, not so much.

[A2C]

VB Wrote:

I highly doubt the A-26 in that picture is doing a loop. You can do a roll and get away with a lot less G's than even non-aerobatic planes are rated for, but a loop, not so much.

Maybe maybe not. The excerpt from the manual says not to do it due to the high wing-loading. This implies to me that the aircraft could enter an inverted spin at the top of the loop. So maybe the risk is low if the plane is stripped down, and plenty of speed is used. Just a guestimate.

[Dudley Henriques]

VB Wrote:

I highly doubt the A-26 in that picture is doing a loop. You can do a roll and get away with a lot less G's than even non-aerobatic planes are rated for, but a loop, not so much.

Maybe maybe not. The excerpt from the manual says not to do it due to the high wing-loading. This implies to me that the aircraft could enter an inverted spin at the top of the loop. So maybe the risk is low if the plane is stripped down, and plenty of speed is used. Just a guestimate.

An inverted spin entry would require stall coupled with a yaw rate. For an inverted spin this means either a stall at -1g or a stall involving a negative pitch rate (accelerated).
This would require a concentrated pitch input to increase the negative aoa on up through the max CL negative.
Could be done but highly unlikely due to the required pilot control inputs.
The high wing loading shouldn't be a loop issue as airspeed and positive g at entry and through the vertical line will control the maneuver.
My guess is that the A26 could be looped with smooth and proper control and power use. I wouldn't recommend it however as a display maneuver for this aircraft. I haven't checked the list, but I seriously doubt any pilot has been waivered by ACES to loop the A26
You are correct about the roll. A nice easy Barrel Roll would be an easy maneuver for this aircraft; again flown by a competent pilot.
Dudley Henriques

[Oscar Duck]

obviously some guys just don't get it. I'm glad they don't fly my aircraft if they want to operate outside of a AFM limits....

If you want to do aeros then fly something that is approved....read the last two sentences!

[img][img]http://i630.photobucket.com/albums/uu23/randalmcfarlane/A26acro0001.jpg[/img][/img]

[Taylor Stevenson]

I don't mean to start anything, but am I the only one who is nervous every time I see WWII warbirds doing low-level acro?


I feel low-level acro should be done in new aircraft built for that purpose, not 60 year old aircraft. These birds can bite even the best of pilots and at 500ft you're toast (I can think of many examples).

Fire lit, running for cover.

[Dudley Henriques]

obviously some guys just don't get it. I'm glad they don't fly my aircraft if they want to operate outside of a AFM limits....

If you want to do aeros then fly something that is approved....read the last two sentences!

[img][img]http://i630.photobucket.com/albums/uu23/randalmcfarlane/A26acro0001.jpg[/img][/img]

Obviously nothing supercedes an aircraft's Dash 1 or Natops restrictions.
The question was answered in the general aerodynamics sense and in that respect the answer is completely correct. Keep in mind that these manuals were written for the average pilot on operations with this aircraft, not a display or demonstration pilot.
The question as it was interpreted asked if the maneuver was possible, NOT whether it was recommended.
The answer made no attempt to alter the written operational recommendations for the aircraft.
Dudley Henriques

[Oscar Duck]

Dudley, of course you are correct re aerodynamics etc.

You need to be a test or approved pilot flying a schedule if you choose not to comply with the AFM. The designers/engineers and then test pilots establish these limits.

Piloting skills aside when we talk about operating registered warbirds then the obligation is on the pilot to respect the limitations of the aircraft AFM and the regulator.

There are many examples of spectacular flying [and accidents] when pushing or exceeding boundaries. I've seen an HS748 50 seat airliner rolled and looped 'off the deck' when I was in the Air Force - didn't make it right however. The court martial was interesting...

[Vessbot]

Oscar Duck,

I'm still not sure whether you're making the accusation or not, but no one in this thread was condoning acro in non-approved aircraft.

[A2C]

The context of the manual says not to do it based on wing loading, so I don't think it necessarily restricts it based on anything else. If the civil plane is lighter, I'm sure it could be done.

[Dudley Henriques]

Dudley, of course you are correct re aerodynamics etc.

You need to be a test or approved pilot flying a schedule if you choose not to comply with the AFM. The designers/engineers and then test pilots establish these limits.

Piloting skills aside when we talk about operating registered warbirds then the obligation is on the pilot to respect the limitations of the aircraft AFM and the regulator.

There are many examples of spectacular flying [and accidents] when pushing or exceeding boundaries. I've seen an HS748 50 seat airliner rolled and looped 'off the deck' when I was in the Air Force - didn't make it right however. The court martial was interesting...

Just want to make sure we're on the same page here as there might be some ambiguity in how the subject issue is being interpreted by each of us.
As someone actively engaged in warbird display flight safety issues almost daily I would heartily agree with you that ALL aircraft, warbird or civilian, should never be flown outside their operational flight strength envelopes.
For the A26 specifically, I would naturally never recommend that the aircraft be displayed in a 3 dimensional aerobatic arena that included the performance of maneuvers specifically restricted by the airplane's Dash 1.
Can the A26 be looped and rolled without overstress considering it's high wing loading? I would answer the question in this context exactly as Vlado did in an above post; Yes, with a caveat.

An aside on the A26 as pertains to it's aerobatic restrictions;
First of all, I agree with the restriction as written so we have no misunderstanding there. This being said, in evaluating the restrictions one has to consider that this airplane did indeed as did the B26 as well, have a high wing loading that could get a young inexperienced pilot coming into the Invader community from OTU or lead in into a WHOLE lot of trouble fairly fast if the aircraft was mishandled in any way. High wing loadings are especially tricky when bank is involved as the wing loads up quickly and high speed stalls are induced quickly and occur without much warning.
The people who wrote the Dash 1 for these airplanes were quite familiar with what could happen and the wording and the restrictions were written to reflect this behavior in the hope of saving lives.
In this respect the warnings for the most part were quite successful.
The restrictions DID save lives.
Dudley Henriques

[Oscar Duck]

Dudley, again correct. The big issue is that we operate warbirds [all aircraft] safely and within the limits and regulations otherwise there is a big risk even for those not directly involved on the day that public perception via media etc can turn against us. [Remember Sacremento]

We had a fatal Strikemaster crash here in Australia a couple of years ago while the owner of the aircraft was carrying out an 'adventure flight'. It nearly caused our regulator to pull the plug on ALL Limited Category aircraft here. The media picture of a wife and children left standing at a country airport not realising that there had been an accident made for dramatic headlines I can assure you.

To this end our organisation Australian Warbirds has joined with the regulator CASA to hold a major Safety Seminar later this month. Most operators here are attending.

the big killer in warbirds is ego!

[A2C]

Good points! I believe, the warbird movement by mass popularity will keep GA advocacy strong if the safety is kept up.

[Towpilot]

VB Wrote:

I highly doubt the A-26 in that picture is doing a loop. You can do a roll and get away with a lot less G's than even non-aerobatic planes are rated for, but a loop, not so much.

Maybe maybe not. The excerpt from the manual says not to do it due to the high wing-loading. This implies to me that the aircraft could enter an inverted spin at the top of the loop. So maybe the risk is low if the plane is stripped down, and plenty of speed is used. Just a guestimate.

Trust me, the A-26 in that picture is NOT on the top of a loop, but just about to gently turn rubberside down again on top of a half cuban eight! I know this for a fact! Also, this specific aircraft has as far as I know never been looped all the way around. As most pilots know, the most stress in such a manouver would be at the end coming out at the same altitud as entering. No need for that, not even for a photo shoot.

Two pilots, 4000 hp and no exra load what so ever except than fuel for less than one hour would put this aircraft in a grossly over-powered completely different setup for aerobatics than the military pilot manual assume.

The pilot in the A-26 in this picture is a highly experienced airline pilot, also a former aerobatic instructor (and crop duster, since we are talking generally about somehow 'out of the ordinary flying' here).