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  #1  
Old 06-26-2018, 08:00 AM
HansR HansR is offline
 
Join Date: Jun 2018
Location: Sweden
Posts: 8
Default RV8 - an aerobatic two seater?

Hi.
I have yet not decided whether to buy a second hand RV8 or RV4.

My main target is to have an aircraft able to do aerobatics with two fullgrown males onboard.

On spec, everything points towards RV8, but when I found a plane of interest, it was with the Mark1 wing, with max aerobatic weight 1500 lbs.
The empty weight is 1140 lbs, leaving just 360 lbs for useful load. Even with the new wing with 1600 lbs aero weight, it is just 460 lbs useful weight. Not much fuel if the crew is 400 lbs.

I checked the RV4. It seems to be 1375 lbs max aerobatic weight, and 930 lbs empty weight, giving a 445 lbs useful load.

As far as I can see, the two planes have about the same useful load, providing a low margin for fuel.

How do you do with your RV4/8? Do you fly aerobatics with passenger?

Does anyone know the design difference between new and old wing?

Do you exceed the max aerob. weight if you stay below 4G?

What other advantages do I get with a RV8 (except a bit more room in the cockpit and more baggage)?

I really want an aerobatic RV, and I would like it to be aerobatic also with passanger. Please help me with the arguments for the two models.
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  #2  
Old 06-26-2018, 08:24 AM
bifft bifft is offline
 
Join Date: Feb 2012
Location: Utah
Posts: 63
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I am still in my test period, so haven't done anything with a passenger yet. Built my 8A as light as I could, currently 1003 lbs with no gear fairing or wheel pants. Tends toward aft CG unlike most RV-8s. Have the old original wing so 1550 lbs aerobatic weight.

Running my weight and balance, with half tanks of gas, it could carry two 170lb people and be in the aerobatic envelope. This requires putting 50 lbs in the front baggage compartment as ballast to get the CG forward enough.

As I haven't weighed 170 lbs since 5th grade, I can only take about 120 lbs for the passenger and be aerobatic. Only have the one parachute, so unless could borrow one someplace don't expect actually doing any two up aerobatics. I have done plenty of aerobatics in the past and never gone over 4Gs, so in theory could do it at higher weights, but that then doesn't leave you with any safety margin for mistakes. I wouldn't do it.

My take is, build it light and the -8 can be a two place aerobatic plane for medium to small pilots. Harder to do with a finished plane, would have to take stuff like heavy batteries, extra radios out.
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  #3  
Old 06-26-2018, 09:48 AM
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donaziza donaziza is offline
 
Join Date: Jun 2007
Location: Atlanta
Posts: 541
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Just my 2 cents worth. Some 5 years ago, I was trying to decide between a 4 and an 8. I rode in the back seat of a 4. It's so tight, I found it to be claustrophobic, and I'm not a big guy---5' 10". So I went with an 8. Now this is just me. Get yourself a ride in the back seat of a 4, and decide for yourself.
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  #4  
Old 06-26-2018, 09:51 AM
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Saville Saville is online now
 
Join Date: May 2014
Location: KBVY Massachusetts
Posts: 813
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Quote:
Originally Posted by HansR View Post
Hi.

On spec, everything points towards RV8, but when I found a plane of interest, it was with the Mark1 wing, with max aerobatic weight 1500 lbs.
I thought that, in general, Mark I wings on an -8 meant an aerobatic load of 1550lbs.
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  #5  
Old 06-26-2018, 10:00 AM
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Mark Albery Mark Albery is offline
 
Join Date: Jul 2007
Location: Fremont CA
Posts: 621
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Typical empty weights are nearer 1000 lbs for the -4 and 1100 lbs for the -8 averagely equipped. So aerobatic payloads are more like 375 lb and 500 lb respectively (assuming -1 wing).

The best combination for aerobatic payload could be an -8 with a fixed pitch wooden prop and a firewall mounted battery. Swapping the Odyssey for an EarthX battery gives you another ~10 lbs.
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  #6  
Old 06-26-2018, 11:59 AM
pjoshyjosh pjoshyjosh is offline
 
Join Date: Aug 2017
Location: Camas, Wa
Posts: 57
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Your post doesn't specify tandem seating?

So is a RV6 or RV7 NOT an option? Both are aerobatic right? With 2 full grown 200lb people and room for luggage right?

Check the specs on a 7.
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  #7  
Old 06-26-2018, 12:01 PM
pjoshyjosh pjoshyjosh is offline
 
Join Date: Aug 2017
Location: Camas, Wa
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I rode in the back of a -8 for about an hour. Wouldn't want to do it again... I'm 6'4" and 225. My legs were basically locked in position around the front seater and couldn't move my feet. When I got out - it was not easy...

I own a -9A (similar size inside to -7) and much more comfortable seating and easier in/out.
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N8306R - PA28-140 Purchased 05/2013
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No N# - RV9/A Kit in progress
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  #8  
Old 06-26-2018, 01:11 PM
flyride flyride is offline
 
Join Date: Apr 2010
Location: Sacramento, CA
Posts: 30
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Having flown aerobatics in both, the RV-8 is a bit easier to fly "two-up" aerobatic aircraft than the RV-4. The RV-4 is much more aft-CG pitch-sensitive with a passenger.

Both aircraft really need to be flown at aerobatic weight for CG reasons, which is very limiting if you have a passenger.

Both aircraft are very pleasant for aerobatics without a passenger.

Of course, every build is a little bit different so YMMV based on individual airframe.
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  #9  
Old 06-26-2018, 01:58 PM
spatsch spatsch is offline
 
Join Date: Nov 2014
Location: Randolph, NJ
Posts: 173
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Quote:
Originally Posted by flyride View Post
Both aircraft are very pleasant for aerobatics without a passenger.
Agree.

As for passengers it depends what kind of acro you want to do. A gentle roll and loop with a passenger isn't a problem. I wouldn't want to use either as a basic trainer. If you are looking for that I would keep looking.

Oliver
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  #10  
Old 06-26-2018, 05:59 PM
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f14av8r f14av8r is offline
 
Join Date: Apr 2012
Location: Tampa (Wimauma actually)
Posts: 349
Default No two up aerobatics in a RV-4

You can't get there, legally in a RV-4. I've owned a -4 and an -8. The RV-4 is just not a two-up aerobat. Cook the numbers however you like but it isn't. Your CG or your weight will be out of whack. Can you load your 200 lb neighbor up and go do loops? Sure. But, just because you can doesn't mean you should. You'll be so far out of CG, and probably overweight, that it will not be a comfortable experience.

The RV-8 is most certainly a two-up aerobat. Just manage the CG appropriately. Depending on the weight of the person in the back seat, you might want to add some weight up front. But, you'll definitely be within the weight limits and you'll be able to manage the CG.
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