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RV-6A rolls and loops at gross

J

jws_39

Active Member
Can you do rolls and loops in the rv6a at 1650 gross with out overstressing it. I know the acro weight is 1350. What I would like to know is what kinda g force are you experencing during a roll or loop? I think you can do +4 -2 at gross. I am looking at purchasing a rv6. I would love to buy the rv7 that is rated at 1600lbs but the buget want let me.

Thanks for your replies

Jeff
 
RV-6 Aerobatics

Yes you can. The airplane has a design 6 g limit (I don't recall the negative g limit - I never go there). My loops call for a 180 MPH entry speed and a 3.5 g pull up, easing over the top, then 3.5 pull out. Most well executed barrel rolls are a 1 g manuever. You can pick up maybe 1.5 on the pullout of an aileron roll. You should never go negative on a loop or a roll.

Although you can do this at gross and not break the plane, it is preferable to be as light as possible. It handles a little better and puts less stress on the airframe.
 
Sort of..

....but it's 6 G's at 1350 which places 8100 lbs on the airplane. 8100/1650 = 4.9 G's. This ought to be the max you pull at gross.

Regards,
 
Acro at gross weight

My -8 isn't flying yet so I do not have any first hand experience flying acro in RVs. However, I've flown acro up through sportsman in a decathlon and have had my share of botched maneuvers. Even simple ones.

I understand that you can loop and roll an RV-6 at gross weight, provided everything goes as planned, but *should you* ? Why increase the risk of bending your airplane, or worse?

I wouldn't recommend that you fly acro at gross weight, particulalry if you are new to acro,

Fly safe,

Mike Draper
RV-8
N468RV
Still working on the baffles.....
 
Aerobatic gross weight for the -6 is 1375#.

I gotta go along with Mike on this one. Just a little "botch" can go a long way.
 
drill_and_buck said:
I understand that you can loop and roll an RV-6 at gross weight, provided everything goes as planned, but *should you* ? Why increase the risk of bending your airplane, or worse?
Click to expand...

I've wondered this as well - I know of one particular instance where the -6A itself is heavy (nearly 1300 lbs), and the owner would fly himself and a pax out for casual loops & rolls.

Clearly this is ok provided nothing goes wrong, but that's not typically the way we are all taught to fly (alternates, reserve fuel, etc.) and I'm not clear on why this particular topic is often treated differently. Like you, my RV isn't flying yet but what I learned from doing acro in a Citabria showed me that when things go wrong it's easy for both the airspeed and G-loads to build quickly. I can only imagine this is more pronounced in the RV than it is in the the Citabria.
 
Empty weight and pilot

I understood that the 1375 lb. limit was for an empty weight -6 plus the wright of the pilot, but that the fuel weight was not factored into this number. Did I misunderstand?
 
When you learn how to aerobat your RV you will be able to fly loops and barrel rolls like Mel at only 2.5g :) Before you get to that standard there will be a few occasions when you will pull a little more. Get some instruction in a Pitts, then start out solo at under 1375lb, once you can reliably pull loops and barrel rolls at less than 3g, then (and only then) start flying acro at over 1375lb. You won't have much margin, so make sure you don't use it all up. I wouldn't pull much more than 4g at gross.

There has been some speculation that the acro weight doesn't include fuel, the argument is that fuel in the wings doesn't add to the wing root bending moment. If I was flying on flight sim I might be inclined to try it out ... As it is I'll stick to 1375lb being the max all up for acro.

Pete
RV-6A
 
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Great info. thanks for all the replies. I have seen a lot of videos on you tube with 2 passengers in the -6 doing loops and rolls. I thought the roll would be the least in the gs. I know they had to be over the acro weights. I really don't want to bend the plane :eek: either. I was just wanting some thoughts on it.
 
jws_39 said:
Great info. thanks for all the replies. I have seen a lot of videos on you tube with 2 passengers in the -6 doing loops and rolls. I thought the roll would be the least in the gs. I know they had to be over the acro weights. I really don't want to bend the plane :eek: either. I was just wanting some thoughts on it.
Click to expand...

My thoughts on it are that just because you see someone do it on YouTube doesn't mean that it's OK....design limits are set by the engineer who designed the airplane, and sometimes the reason isn't all that obvious. Before I exceed ANY limits set by the designer, I would want to know exactly what determines that limit. You might be surprised.

Of course, people get away with things every day - heck, I've been known to exceed the speed limit now and again...:rolleyes: That doesn't make it right, or even smart. The question I'd ask is "Unless you really KNOW what you are doing to an airframe, do you really have the right to put your passenger at a potentially elevated level of risk?"

Just thoughts for consideration....

Paul
 
Eh?

Nukeflyboy said:
. Most well executed barrel rolls are a 1 g manuever.

.
Click to expand...

How so?...A barrel roll is a loop and a roll at the same time..If the loop takes 3+ G then how does a barrel roll not be #+Gs as well?

Or am I doing mine wrong??

Frank
 
I think he meant "aileron rolls". A properly executed aileron roll will exceed 1G, but not by much.
 
frankh said:
How so?...A barrel roll is a loop and a roll at the same time..If the loop takes 3+ G then how does a barrel roll not be #+Gs as well?

Or am I doing mine wrong??

Frank
Click to expand...

I was taught barrel rolls are a 1G manuver. I can't do it at 1G, but I can do it fairly close to that (varying from .5G - 1.5G or thereabouts) in a Citabria.
 
Terminology

In the Cole book "Roll Around a Point," hey, I might as well refer to it since it has "roll" in the title, he talks about three kinds of rolls, slow rolls, snap rolls and barrel rolls. I think most of us understand the differences in these maneuvers. I had done all these rolls before I flew an RV.

There is a type of roll that the RV does very easily that I consider a hybrid. It involves establishing a nose-up attitude, releasing back pressure and putting in aileron until you are upright. It is really easy, if you don't apply back pressure while upside down. I guess this is what people refer to when they talk about an aileron roll.

The nose traces a pretty small circle when doing this type of roll, but if observed from outside the airplane it looks pretty much like a barrel roll, although control inputs are a bit different.

I can do this roll at very near one g. If you closed your eyes you wouldn't be able to tell anything happened. I'm not sure what Bob Hoover calls the kind of roll where he is pouring iced tea backhand, probably a barrel roll, but whatever it is, he can't be pulling much g or he wouldn't be able to hold a pitcher of tea backhand, with his arm extended. http://www.youtube.com/v/Xp2Uc9XvmjY&hl=en" type="application/x-shockwave-flash" width="425" height="344"

As for a barrel roll being a roll and a loop, thus needing loop type g loadings, I don't get that one.
 
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pierre smith said:
....but it's 6 G's at 1350 which places 8100 lbs on the airplane. 8100/1650 = 4.9 G's. This ought to be the max you pull at gross.

Regards,
Click to expand...

The calculation above is correct in that it shows the lifting force necessary to fly a 4.9 G maneuver at 1650 lbs, however it does not address bending moments at the wing root which is the likely limiting factor in the structure.

You will almost certainly exceed the design limit, if not the failure limit, of your wing if you pro-rate your g limit based on the ratio of your actual weigh vs the aerobatic weight limit. Why? Because wing root bending moments increase faster than lifting forces on our airplanes because the majority of the aircraft and payload weight is housed in the fuselage.
 
RV-6

The RV-6 is the strongest of the wings of the RV series. Someone a long time ago said they loaded to 13gs during testing and they did not fail. You will pull the tail off before the wings fail. Two big guys in a 6 once did a low level loop and had to pull out of it really hard to avoid impacting the ground. They pulled close to 9gs and made it back alive. The wings held but the tail cone was wrinkled. Not good and not smart. As far as the 1350lb limit is concerned. Remember way back when RV's were powered by 160hp engines and wood props :eek:and the empty weight was 900lbs:cool:. 1350 would give you one person and some gas. But no one builds these kind of planes anymore:mad:. I would caution doing any acro at gross. It just isn't smart and no room for error. RV's can be stressed a lot easier than normal planes due to their responsiveness and high speeds.
 
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27 Years of the RVAtor

Anyone owning or considering an RV should own and read this book. It's avail on Van's site. Lengthy discussion of G loading, Vne, CG effects, much more.
 
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