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  #1  
Old 05-09-2014, 11:36 AM
FLY6584's Avatar
FLY6584 FLY6584 is offline
 
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Default RV-4 aerobatics question...

I'm interested in purchasing an RV-4. It will primarily be used for fast economical x-country transportation, but occasionally I'd like to take some friends up to do some aerobatics.

Is that even possible? I'm 200lbs so is it possible to perform aerobatics with a rear passenger and if so what kind of weight will that person be limited to and what kind of fuel load will I be limited to?

Thanks!
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  #2  
Old 05-09-2014, 12:27 PM
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WillyEyeBall WillyEyeBall is offline
 
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Default passengers and aerobatics

In a RV-4, I would not recommend aerobatics with a passenger regardless of their weight except an aileron/ barrel roll (clearing maneuver, no Gs). I've had my RV for 10 years and even with a good looking 120 lb. passenger strapped in, the pitch becomes so sensitive, you can very easily overstress the airplane before you know it. With a 200 pounder, it's a nightmare. Also, when you go zero to negative Gs and into positive, there is a slight lag before their butt hits the seat which really increases the pitch. Then there is the weight of the required parachutes. If you search on this site, you can find this discussed before. Would recommend a RV-8 or a side by side (RV-6-7-14) for any dual aerobatics. By the way, puke on the back of the head ruins the mood.
Bill McLean
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  #3  
Old 05-09-2014, 12:45 PM
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Lol. Good to know. I've been doing a lot of reading and it seems pretty split. Some people say no way and others say good to go as long as they aren't too heavy and you keep it to the minor stuff.
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Old 05-09-2014, 01:05 PM
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There's an aerobatic maximum weight that's below your normal, allowable gross weight....don't know what it is for the -4 but the RV-6 has a normal gross of 1600 lbs, IIRC, and an aerobatic maximum of 1350 lbs, so check the manual or someone on here may chime in.

Best,
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Old 05-09-2014, 01:50 PM
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Aerobatic gross weight for the RV-6 is 1375 lbs. I believe for the -4 it's 1275.
I could be wrong on the -4.
On the other hand, there have been people get into trouble doing aerobatics in a -4 with an aft CG.
I do not recommend it at all!
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  #6  
Old 05-09-2014, 02:17 PM
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Well you will get varied opinions so I'll offer contrary view. The -4 is more sensitive in pitch with some one in the rear seat. Simple flight dynamics dictates a conventional aircraft will get more pitch sensitive with a more aft CG location. But how sensitive is too sensitive? The answer to that one is subjective and varies with pilot and experience.

When I first flew the -4 I noticed the change of pitch sensitivity a lot when someone got in the back. Now I just don't seem to notice it. I can tell its there but seem to adjust without noticing it all that much. I don't consider myself some super stick jock but I wouldn't be a pilot worth being called that if I didn't think I was "above average". Maybe I should have grown up in Lake Wobegone….

As others have pointed out the critical limitation is the aerobatic gross weight. Start with a 200 lb pilot, add in a normal sized backseater, and pretty soon you don't have room for go juice. But assuming you can make the numbers work I see no reason not to do aerobatics with a passenger in a -4. Since its probably not nearly as much fun for them as it is for you the question might well be - "Why would you want to?".
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  #7  
Old 05-09-2014, 02:49 PM
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Quote:
Originally Posted by Mel View Post
Aerobatic gross weight for the RV-6 is 1375 lbs. I believe for the -4 it's 1275.
I could be wrong on the -4.
On the other hand, there have been people get into trouble doing aerobatics in a -4 with an aft CG.
I do not recommend it at all!
Mine (RV-4) shows 1375 lbs
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  #8  
Old 05-09-2014, 03:14 PM
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Russ McCutcheon Russ McCutcheon is offline
 
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I think it’s safe to say that the CG is no more or less important than the Gross weight, both are critical.

As far as the go juice, some have stated including the tall soft spoken fellow himself that with the use of some prudence and common sense the weight of fuel in the wings could be eliminated from the gross aerobatic weight calculation.

Every one of these RV-4s has a different empty weight and different CG, you need to run the numbers for what you want to do in whatever airplane you’re looking at and use your best judgment based on the math and your skills.

I have found that some passengers enjoy a roll and a couple of big steep wingovers very much, all done legally with shoots etc.
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  #9  
Old 05-09-2014, 03:32 PM
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Andy Hill Andy Hill is offline
 
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Quote:
with the use of some prudence and common sense the weight of fuel in the wings could be eliminated from the gross aerobatic weight calculation
Pure physics would state this might have some validity if, when you overstress the aircraft, the wings break at the root.

A read of the RV-8 double fatality NTSB report reveals both wing spars broke mid-span i.e. outside the tanks.

Max Aeros Weight 1550lbs, actual AuW 1639lbs. Max RV-8 Fuel 252lbs. Not specified in report, but I would guess if you discounted the fuel on board, it is likely ZFW was "approx" Max Aeros Weight.

(RV-4, RV-8 and others have "similar" structural designs).

I am not saying you cannot discount fuel - it is a "grey" area to some... but I would not

The Australian RV-4 accident report also worth a read.
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Old 05-09-2014, 03:56 PM
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A decade ago I was riding in the back of an RV4 fairly often. Upside down on nearly every flight at least once. Rolls, loops, snap rolls and every combination therein. I was approximately 185lb, pilot was about the same. We often had full fuel.

I am by no means an aerobatic expert. In fact, calling me a rookie would be complimentary. But, like everything in an aircraft, one must use a bit of common sense (which I will concede isn't as common in pilots as could be hoped). Did he ever go out and pull the aircrafts max G? No he did not. Gentleman acrobatics, nice and easy. If an airliner can be induced to roll without pulling the wings off....I suspect an RV4 with a passenger wont be a problem for a pilot with some skills. The gent in the front seat was easily up to the task and he kept me from doing anything stupid in the back.

I certainly wouldn't go out and learn aerobatics in an RV4 with a passenger (unless I was learning as the passenger perhaps), but I've been in an RV4 with a 360/CS doing aerobatics and I'm still here. Of course, we each must decide for ourselves where our limits lie.
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Last edited by ColoRv : 05-09-2014 at 04:08 PM.
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