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  #11  
Old 05-09-2014, 05:09 PM
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Russ McCutcheon Russ McCutcheon is online now
 
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Quote:
Originally Posted by Andy Hill View Post
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.
That RV-8 pulled 9+Gs, I would say prudence and common sense got lost that day, the -8 spar is also different now and also different then an RV-4. Prudence and common sense is code for gentleman aerobatics.
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  #12  
Old 05-09-2014, 05:12 PM
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Quote:
Originally Posted by ColoRv View Post
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.
Your experience is the same as mine both from the front seat and the rear seat of my RV-4.
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  #13  
Old 05-09-2014, 05:27 PM
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FLY6584 FLY6584 is offline
 
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Great discussion here... thank you for the feedback. I am torn between the -4 or the -3 right now.

My wife is moving down to Florida this year to go back to school and we live in Georgia so I'm looking for cheap and fast transportation down there every weekend. I've run the numbers and fuel costs will be quite similar between making a 6hr drive in the car and a 2hr flight in the RV so it's a no-brainer for me. Plus I can keep the aircraft on base for really cheap.

She will occasionally and I mean very occasionally fly with me down to the Keys and places like that in FL, but the only other time I will have passengers is when a friend wants to go up for some aerobatics. Honestly if it's already cutting it close as it is I'm starting to lean towards the -3 to save some money.
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  #14  
Old 05-09-2014, 05:46 PM
Slats Slats is offline
 
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Default I know I'm new.....

so I may be missing something.

My 4 weighs 1035 empty, she has an old CS prop and so is a bit heavy. I weigh 200 for a sub-total of 1235.

My aerobatic gross is 1375 - 1235 = 140 lbs.

My favourite passenger is also 120 lbs (with whom I have never done aerobatics), which leaves 20lbs fuel or about 3.5 gallons, roughly the vfr minimum.

So, by my calculations, I can strap both of us in and start the engine but not take off as I won't have my 30 mins vfr fuel.

I am in the process of certifying my plane for aerobatics and read the Austrailian accident investigation as part of my homework. The lesson seemed clear to me.
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  #15  
Old 05-09-2014, 06:04 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Slats View Post
so I may be missing something.

My 4 weighs 1035 empty, she has an old CS prop and so is a bit heavy. I weigh 200 for a sub-total of 1235.

My aerobatic gross is 1375 - 1235 = 140 lbs.

My favourite passenger is also 120 lbs (with whom I have never done aerobatics), which leaves 20lbs fuel or about 3.5 gallons, roughly the vfr minimum.

So, by my calculations, I can strap both of us in and start the engine but not take off as I won't have my 30 mins vfr fuel.

I am in the process of certifying my plane for aerobatics and read the Austrailian accident investigation as part of my homework. The lesson seemed clear to me.
I don't know the Australian rules, but for the US folks following along, don't forget to add two parachutes at about 20 lbs each.....

I've done this math for our -8 and our -6....which is why I essentially never fly aerobatics with passengers.
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  #16  
Old 05-09-2014, 09:31 PM
Christopher Murphy Christopher Murphy is offline
 
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Default rv-4 acro with a pax

The folks who are discouraging acro with a passenger in the -4 ( especially if it puts the cg at the back of the envelope) know what they are talking about. It is not really a two seat aerobatic aircraft and if you end up spinning out of a botched maneuver it might end up in a bad way.

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  #17  
Old 05-09-2014, 11:54 PM
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Quote:
Originally Posted by Christopher Murphy View Post
The folks who are discouraging acro with a passenger in the -4 ( especially if it puts the cg at the back of the envelope) know what they are talking about. It is not really a two seat aerobatic aircraft and if you end up spinning out of a botched maneuver it might end up in a bad way.

Chris M
Yes but the people that have done it are not necessarily stupid either, I have done quite a bit of it myself and agree I would not do it near the aft limit, that would not be good judgment or prudent, for anyone that has flown an RV-4 at the aft limit (I have) they would or should recognize it would not be wise to do any acro, run the numbers, know what your skill level is and feel what the airplane is telling you in flight, if any of these donít look/feel right then pass on the acro, itís still a great ride right side up.
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  #18  
Old 05-10-2014, 01:49 AM
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Andy Hill Andy Hill is offline
 
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Hi Russ

Quote:
That RV-8 pulled 9+Gs, I would say prudence and common sense got lost that day, the -8 spar is also different now and also different then an RV-4. Prudence and common sense is code for gentleman aerobatics.
The 8 spar was altered only in a minor way, and is substantially same design as 3/4/6/7.

My post was not directed at whether RV-4 aeros 2 up is good / legal. It was purely directed at the idea of discounting wing fuel for aeros weight purposes.

Are you suggesting the RV-8 change, and the RV-4 wing differences, are such that pulling excess 'g' with full fuel will still see the wings fold at the root and not mid-span?
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  #19  
Old 05-10-2014, 05:29 AM
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pierre smith pierre smith is offline
 
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Dan, there are aerobatics and "Gentleman" aerobatics, as you well know.

The gross weights are listed to save the spar/wing. I have and you can do gentleman rolls...little or no extra G's, with a passenger...no loops because then things can get dicey quickly.....and no demos of fighter tactics either. To a non-flyer or a pilot with no aerobatic skills, a simple aileron roll is a real treat and safe too.

Let common sense prevail and you'll be fine.

Best,
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  #20  
Old 05-10-2014, 06:39 AM
Nate-ISU Nate-ISU is offline
 
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One more (personal) data point:

My -4 is an early model, kit 126 completed in 1983 that weighs in at 1020# with inverted fuel/oil. While little has changed overall, the last W&B was over 20 years ago so I expect that number to be slightly off, maybe +10/-10#. She'll be getting a new W&B at CI this month.

Onto the point--I've run the numbers and with full fuel and a 180# pilot [me], I'm slightly over the aerobatic gross of 1375. Since I currently don't own a 'chute and the front is only a 3-pt harness, I personally refuse to do sustained inverted and anything over 3g. Even still, I've had plenty of fun getting to know the plane, building skill, and growing confidence in it's build during this past year.

If I had a 100# passenger in the back, I'd be fine doing 2G maneuvers; steep turns, aileron rolls, mock dog-fighting sort of stuff. If I had a typical 180# passenger, nothing more than an aileron roll and some easy wing overs.

The numbers by Vans are clear. I'm willing to push them to a finite point based on my ability, confidence in the airframe, and experience others have noted here and in the past. In all reality, I'm most concerned about CG & gross weight at landing since typical passengers don't have the lust for aerobatics that I do.

Last edited by Nate-ISU : 05-10-2014 at 06:53 AM.
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