The International Cessna^® 170 Association

I'm fond of thinking that a barrel roll is OK in any airplane that has sufficient ailerons to produce an acceptable roll-rate. If only required crew is carried then no parachutes are required. If not performed over a congested area, near an airway, and above 1500', then it's perhaps technically legal. A barrel roll is nothing more than an un-arrested turn. Your coffee cup stays right there on the dash and the coffee stays right there in the cup. It is a 1 G manuever.
Neither a loop nor a spin recovery are 1G manuevers. But that is not the point. Not attacking Rob here. Bob Ptui Hoover performed many displays of aerobatics that AeroCommander was not approved for without any harm whatsoever to the plane. But the kind of thinking that leads to the sort of conclusion that the airplane can perform unapproved manuevers and still survive so let's try some... is the kind of thinking that leads a weak-minded pilot to attempt things he shouldn't. When he's lucky nothing bad happens. Being lucky does not make the pilot good. Or "hey watch this" bright.
I've had moments that were weak minded and lucky. But that does not provoke me to conclude that it's a good idea to tell others they might be as well, ...so go do some unapproved manuevers to impress your friends. In fact, to really impress them, do them with your friends aboard! Post a video!

I hope you don't think I was attacking you Robbie. I certainly didn't mean to.
George a barrel roll is basically a loop while doing an aileron roll, you basically roll at a rate that will put you 90 deg. to your initial heading when you reach the inverted position, and then continue at that rate so that you are back on your initial heading when right side up again (you will be displaced laterally from your entry point. This too, will require something more than 1 G. I have not had the chance to perform aerobatics in twenty years, it was the most enjoyable part of my flight training. If I remember correctly, we did these maneuvers at around 3 1/2 Gs, which would also deform a loop, but that wasn't the purpose of these maneuvers. The hardest part of doing these barrel rolls was trying to imagine what the horizon would do when preparing for the flight the night before while armchair flying, it can be a bit confusing.

David

dacker wrote:I hope you don't think I was attacking you Robbie. I certainly didn't mean to.
George a barrel roll is basically a loop while doing an aileron roll, you basically roll at a rate that will put you 90 deg. to your initial heading when you reach the inverted position, and then continue at that rate so that you are back on your initial heading when right side up again (you will be displaced laterally from your entry point. This too, will require something more than 1 G. I have not had the chance to perform aerobatics in twenty years, it was the most enjoyable part of my flight training. If I remember correctly, we did these maneuvers at around 3 1/2 Gs, which would also deform a loop, but that wasn't the purpose of these maneuvers. The hardest part of doing these barrel rolls was trying to imagine what the horizon would do when preparing for the flight the night before while armchair flying, it can be a bit confusing.

David

If someone taught you to do a barrel roll that took 3.5 G's then they taught you wrong. A barrel roll is a 90-degree steep turn that is allowed to continue beyond the 90/180 degree bank and the pitch is relaxed (perhaps even negated slightly) at the upside-down point, then re-instated at the right-side-up point....is the best way to describe it. It is a "1-G" manuever if done gently...a 1.25-G manuever if done carelessly... perhaps a 3.5-G manuever if done aggresively and/or violently because of pilot-panic at the 3/4 point in the turn. The latter is a failure to perform the manuever correctly. IMHO
The hardest part is finding a place geographically that does not violate the FAR's.

Gee George, I guess you also call it ACROBATICS! What you seem to be attempting to describe is commonly called an aileron roll (slow roll, snap roll, 8-point roll, etc) and is done about the longitudinal axis and you are correct - it is a 1G maneuver. What you so eloquently blasted me for... using 3 1/2Gs, is what I and thousands of other Naval Aviators were taught, I can only surmise that this is the beginning of aeial combat maneuver training, I wouldn't know, I went the rotor-head route. This is one of those common mistakes the world seems to make, just like calling it ACROBATICS, which by the way the FAA also does. If you still don't get what I am trying to describe (semantics aside) it consists of a hard pull up while beginning a roll, I believe the target is 45 degrees of heading change at the vertical, 90 degrees of heading change at the inverted position, 45 degrees heading change towards the original heading at the vertical (nose down), then back on heading at straight and level. Basically a corkscrew. It cannot be done at 1 G, no negative Gs at all. The C-170 is probably capable of doing it with proper energy management, but you want find me attempting it.
I find this a bit amusing, because I know you have years more experience than I (which may account for why you have a lot more gray hair than I do, but at least you have hair ), yet you still call the aileron roll a barrel roll like most layman.
David

Actually, your description of the barrel roll is more in keeping with tradition (except for the "hard pull up".) It's been described that way in other places I'm familiar with, and I should have used it rather than try to reinvent the wheel with my ad hoc description. I know what a barrel roll is. But you're incorrect in it's stesses. It's a near 1G manuever if properly performed. Can be quite gentle.
The aileron roll is a roll about the longitudinal axis only and involves both positive and negative G's and may also be no more than 1G in either direction. It does not involve any turning. Some poorly executed "aileron" rolls are actually a loss of altitude while rolling about the axis....not the pretty things usually viewed at airshows.
A "snap" roll is a spin in the horizontal direction. It can be quite violent and can rip the tails off aircraft not designed for them. The 170 would likely suffer airframe failure from an attempt at a snap roll at speeds necessary to perform the manuever.
While not a naval aviator, I am a graduate of Gene Soucy's aerobatics courses, both basic and advanced, and know how to perform these sort of simple rolls.

gahorn wrote: A "snap" roll is a spin in the horizontal direction. It can be quite violent and can rip the tails off aircraft not designed for them. The 170 would likely suffer airframe failure from an attempt at a snap roll at speeds necessary to perform the manuever.
.

I was taught that a snap roll is done at maneuvering speeds, when it supposedly is safe to use full or "abrupt" control surface deflections with no structural damage. YMMV

regards

~Marc

Yes a barrel roll is a beautiful and gentle maneuver when done well... the 3+ Gs that I used way back when were per training future naval aviators, some who would go on to fly the world's best fighters. Some of us real pilots went on to fly even betterl flying machines known as helicopters . The aerobatics taught were not necessarily taught to be the beautiful symmetric maneuvers that are used in aerobatics competition, but were more an introduction to unusual and extreme attitudes to see if the students had the stomach for that sort of thing. It in no way made aerobatic experts of us. I only wish I also had an aerobatic airplane to learn more in.
David

No offence taken to any replys to my post. This is a good group.

Interesting side note. The IAC (International Aerobatic Club) describes the Barrel Roll as 2.5-3 Gs max, 0.5 Gs minimum. There is a chart on their website that describes the different maneuvers if anyone is interested.
David

Plummit wrote:

gahorn wrote: A "snap" roll is a spin in the horizontal direction. It can be quite violent and can rip the tails off aircraft not designed for them. The 170 would likely suffer airframe failure from an attempt at a snap roll at speeds necessary to perform the manuever.
.

I was taught that a snap roll is done at maneuvering speeds, when it supposedly is safe to use full or "abrupt" control surface deflections with no structural damage. YMMV

regards

~Marc

A snap roll is an accelerated stall, with the spin induced by rudder application at the moment of the break.
The snap roll, when performed in an airplane approved for them, is usually performed at a specified speed. That speed is commonly the manuevering speed for that airplane.
My comment was that a snap roll, performed in a 170...would likely damage the airplane. This is because the rudder of a 170 is insufficient to provoke a completely successful snap roll ... so ....unless the speed were brought up to such that the rudder could provoke the snap... This would be far above the manuevering speed of a 170... so therein my comment: The 170 would likely suffer airframe failure from an attempt at a snap roll at speeds necessary to perform the manuever.

(And is probably why the manuever is not approved for the airplane.)

George, while this general subject is being bantered about, I have a question regarding a loop. A longtime, now deceased, friend who was a homebuilder, AAF P-47 pilot in WWII (180 missions), did flight evalualtions on captured enemy aircraft @ Wright Field, was a test pilot at Muroc/Edwards, set a speed record in 1948 in a F-86 (Thompson Trophy), 7 combat mission in Korea in F-86's, first flight of the Convair F-102, F-106, GD F-111 & supervised the Convair B-58 Hustler test program , Bell X-1 (probably more hours than any of us 170 members)and the receipient of a Silver Star, Legion of Merit, 4 DFC'c & 14 air metals, several national & international aviation awards incl. the Kinchloe Award in 1968 as the nation's top test pilot (Yes I am proud to have known him and had the honor of doing a lot of flying with him. Wish I had recordings of all of his flying experiences.) once taught me how to do a loop in my C-140A. Being a pilot who dislikes spins, other than in true aerobatic aircraft, I was a bit reluctant, but agreed to the task. It turned out to be a blast and one easy to do. He cautioned me about getting too slow on the top of the loop, which I did a couple of times & discovered how much "stuff" was in the floorboard and also about not pulling out of the loop too aggressively. The pull out at the bottom, he said, was the most likely place to overstess the airframe. I did a bunch of them solo as well as with passengers, all without incident (above example excepted). Now to my question---I thought he told me that a properly executed loop was a 1 G manuver Maybe I misunderstood. Maybe he said a properly excuted loop would not exceed the certified positive/negative loading of the airframe. Just want to know what is correct. Incidently, I have never loop my C-170C---that green & white paint makes it go so fast that I am afraid to try it And yes, George, it might be advisable to put on your boots as the BS does sometimes flow freely around here

You make an excellent point, Frank. When speaking colloquially about a "1G" manuever, ... it's unlikely we are actually observing a G-meter and taking an accurate reading... we are most likely using our calibrated butts to take that measurement. This entire discussion of how many "G's" a manuever produces is so subjective. It depends on individual pilot technique as well as how much energy that pilot wishes to expend in the manuever. If he wants a small, tight loop performed at higher speeds, it's going to produce higher G-forces.
If you make a 60-degree bank, 360-degree turn, at a level altitude with no climbing or descending during the manuever, you will experience approximately 2-G's thru most of it, certainly by the 180-degree point in that turn, due to centrifugal forces. Using that as a guideline, a well executed "gentle" loop would probably rate about 1.5-2 "G's". (And in retrospect, the barrel rolls I discussed previously would be more than an actual "1G". I imagine most pilots would tend to underestimate G-forces on such mild manuevers. I recall performing Cuban-eights in the CAP-10 and was surprised to find 2-G's registered at the bottom of the manuever. This is about what I recall seeing in most "gentle" loops, ... although a loop performed in a "box" would be more aggressive.
Keep in mind that "show" aerobatics are much more aggressive because the performer must stay in a "box" above the runway. The gentle manuevers I've been describing would take large amounts of airspace in order to keep them below 2-G's. Dave Acker's description of barrel rolls, as taught by most military pilots, are crisp, abrupt manuevers, performed within a smaller area and that probably explains the difference in our different, subjective, perceptions of them.
Imagine, one pilot performing a stall so well that the horn sounds, and the power increases, and the airplane hardly de-stabilizes... And another pilot's technique is "SLAM!" - the throttle forward, "SLAM" - the stick forward, "DUMP" the nose down, "PORPOISE" the pitch several cycles, ...and then the airplane struggles out of the situation.
Both performed a stall recovery. Which one would influence the G-meter more?

Thanks for the clarification George.

Sounds like George was just describing my first landing attempt in Kelowna. Is it too early to talk about Galveston?

As I sit here at my computer I'm at +1G. If I looked at a G meter next to my computer it would be at rest. It is of course reading +1G. So not having a G meter in a helicopter what does a G meter read on the dial at rest, 1 or 0?

I've never thought about it.