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  #21  
Old 07-01-2018, 08:09 AM
Robert Anglin Robert Anglin is offline
 
Join Date: Mar 2008
Location: houston, texas
Posts: 822
Default Weight and C.G. location.

You should not need to replace the wing. The older style is only 50Lbs, less suggested weight limit for Aero, than that of the dash one wing. The rear C.G. limit will stay the same for both. It would be a lot less work to reduce and shift weight around in the airframe and you can do that as you go. I would and have done just that on our 8. After very carefully building it, we still found that we could improve our utility by removing as much weight aft of the C.G. and for that matter from the whole aircraft. Then shifted as much of what we had to keep, forward to get the C.G. as close to the front of the C.G. envelope as we could. It is a nice platform and you can work with it to make it to fit a number of missions. With the 8 most all of the weight is loaded aft of the empty C.G. before you leave the ground. If you try to get both the empty weight down and the empty C.G. as close to the front as you can, you well have one that can be used for most of the fun and those other trips you will want to make.
Good luck your got a good start. Yours, R.E.A. III # 80888
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  #22  
Old 07-03-2018, 12:54 AM
HansR HansR is offline
 
Join Date: Jun 2018
Location: Sweden
Posts: 16
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Quote:
Originally Posted by Robert Anglin View Post
You should not need to replace the wing. The older style is only 50Lbs, less suggested weight limit for Aero, than that of the dash one wing. The rear C.G. limit will stay the same for both. It would be a lot less work to reduce and shift weight around in the airframe and you can do that as you go. I would and have done just that on our 8. After very carefully building it, we still found that we could improve our utility by removing as much weight aft of the C.G. and for that matter from the whole aircraft. Then shifted as much of what we had to keep, forward to get the C.G. as close to the front of the C.G. envelope as we could. It is a nice platform and you can work with it to make it to fit a number of missions. With the 8 most all of the weight is loaded aft of the empty C.G. before you leave the ground. If you try to get both the empty weight down and the empty C.G. as close to the front as you can, you well have one that can be used for most of the fun and those other trips you will want to make.
Good luck your got a good start. Yours, R.E.A. III # 80888
Thank you for the advice. My RV has a Hartzell C/S prop, so that should put the CG a bit forward.

Now I will just have Mitchell Lock to confirm the 1550 as opposed to the 1500.
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  #23  
Old 07-03-2018, 12:58 PM
RhinoDrvr RhinoDrvr is offline
 
Join Date: Jun 2014
Location: Lemoore (Fresno), CA
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Keep in mind "Aerobatic" gross weight is only required if you intend on pulling between 4.4-6 G's in the airplane. The airplane doesn't care what it's attitude is, all it cares about is load factor.

If you execute a loop at 3G's you are legal all the way up to 1800lbs, since you haven't exceeded the 4.4G Normal (Utility?) Category load factor.

My -8 with the non-1 wing weighs 1164 empty (complete steam gauge IFR panel, primed, metal Hartzell non-blended airfoil prop) and I have imposed a 4 G limit on the airframe for ALL maneuvers. Therefore "aerobatic" gross weight isn't a thing. I've got zero desire to pull 6 G's my airplane, ever. The only thing I'll do that in is made of composite with two jet engines on it.

Just my .02 cents. With that mindset two 200lbs adults with parachutes (430lbs) and 20 gals of fuel are legal to do aerobatics, and get the $100 hamburger.

Now, that means that you need to be careful not to exceed 4.4 G's at all during the flight, including any botched maneuvers, but I believe that is a realistic goal. Shooting for 3G pulls, that gives 1.4 G of overshoot.
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Evan Levesque
RV-8 N88MJ (Built by Michael Robbins)
Lemoore, CA
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  #24  
Old 07-04-2018, 04:34 AM
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ronschreck ronschreck is offline
 
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Location: Gold Hill Airpark (NC25), NC
Posts: 1,319
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Quote:
Originally Posted by RhinoDrvr View Post
Keep in mind "Aerobatic" gross weight is only required if you intend on pulling between 4.4-6 G's in the airplane. The airplane doesn't care what it's attitude is, all it cares about is load factor.

If you execute a loop at 3G's you are legal all the way up to 1800lbs, since you haven't exceeded the 4.4G Normal (Utility?) Category load factor.

My -8 with the non-1 wing weighs 1164 empty (complete steam gauge IFR panel, primed, metal Hartzell non-blended airfoil prop) and I have imposed a 4 G limit on the airframe for ALL maneuvers. Therefore "aerobatic" gross weight isn't a thing. I've got zero desire to pull 6 G's my airplane, ever. The only thing I'll do that in is made of composite with two jet engines on it.

Just my .02 cents. With that mindset two 200lbs adults with parachutes (430lbs) and 20 gals of fuel are legal to do aerobatics, and get the $100 hamburger.

Now, that means that you need to be careful not to exceed 4.4 G's at all during the flight, including any botched maneuvers, but I believe that is a realistic goal. Shooting for 3G pulls, that gives 1.4 G of overshoot.
I suppose you are correct BUT I paid for and built an aerobatic airplane and I intend to use every bit of the flight envelope that I paid for!
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Ron Schreck
IAC Director and National Judge
RV-8, "Miss Izzy", 2100+ RV Hours
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"He who demands everything that his aircraft can give him is a pilot; he that demands one iota more is a fool."
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  #25  
Old 07-28-2018, 06:32 AM
HansR HansR is offline
 
Join Date: Jun 2018
Location: Sweden
Posts: 16
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Hi all and thanks for all advice!

Vans has confirmed that aero weight for old wing is 1550 lbs, so Mitch was wrong, with is in this case a very good thing.

I have bought the RV, and the seller did not have all the facts right, so the empty weight is lower than advertised, and actually the full gross weight was also wrong!

Doing the calculations, I can see I will pass the CG limit before the aero gross weight limit, so a -1 wing would not help me.

How sensitive is the RV-8? If I do aerobatics with maybe an inch of off CG, would that be a real issue?

Futhermore, the aerobatics was not tested and included in the POH, so I will have to do that.

What aerobatic manoeuvres is the RV-8 capable of? I would like all suitable manoeuvres in the book.
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  #26  
Old 07-28-2018, 11:07 AM
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ronschreck ronschreck is offline
 
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Location: Gold Hill Airpark (NC25), NC
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Quote:
Originally Posted by HansR View Post
Hi all and thanks for all advice!

Vans has confirmed that aero weight for old wing is 1550 lbs, so Mitch was wrong, with is in this case a very good thing.

I have bought the RV, and the seller did not have all the facts right, so the empty weight is lower than advertised, and actually the full gross weight was also wrong!

Doing the calculations, I can see I will pass the CG limit before the aero gross weight limit, so a -1 wing would not help me.

How sensitive is the RV-8? If I do aerobatics with maybe an inch of off CG, would that be a real issue?

Futhermore, the aerobatics was not tested and included in the POH, so I will have to do that.

What aerobatic manoeuvres is the RV-8 capable of? I would like all suitable manoeuvres in the book.
Hi Hans,

Congratulations on your purchase. You are going to love the RV-8!

Please be careful to stay withing the published CG and weight limits of the RV-8. With the CG an inch forward of the aft aerobatic CG limit the aircraft is very responsive and not twitchy. I have added ballast to my RV-8 tail to put the CG about one and a quarter inch forward of the aft aerobatic CG limit and find that is the sweet spot for solo aerobatics.

The aircraft is capable of all of the maneuvers in the IAC Sportsman sequences (roll, loop, immelmann, split S, cuban 8, spin and hammerhead turns) and most competition RV pilots fly in that category. The Intermediate IAC sequences can be flown in the RV-8 but there are more negative G figures and snap (flick) rolls. Snap rolls can be done but you should become very proficient in the aircraft before you attempt snaps. I so snaps between 100 and 110 knots and have never exceeded 4 Gs during the maneuver.
If you are new to aerobatics you should get some dual instruction in spin and unusual attitude recoveries. It doesn't have to be dual in an RV. The basics recoveries are the same for most aircraft. And practice aerobatics with enough altitude to do two botched recoveries and still have enough altitude for a successful third attempt!

Van wrote a very good article about IAC Aerobatics in the RV. It's in the August issue of the EAA Sport Aviation Magazine. You can find it in the EAA.org archives if you are a member. Or you can send me your email address via private message and I'll send you a PDF of the article.
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Ron Schreck
IAC Director and National Judge
RV-8, "Miss Izzy", 2100+ RV Hours
Track Me
VAF 2018 Donor
"He who demands everything that his aircraft can give him is a pilot; he that demands one iota more is a fool."
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  #27  
Old 07-28-2018, 12:03 PM
HansR HansR is offline
 
Join Date: Jun 2018
Location: Sweden
Posts: 16
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Quote:
Originally Posted by ronschreck View Post
Hi Hans,

Congratulations on your purchase. You are going to love the RV-8!

Please be careful to stay withing the published CG and weight limits of the RV-8. With the CG an inch forward of the aft aerobatic CG limit the aircraft is very responsive and not twitchy. I have added ballast to my RV-8 tail to put the CG about one and a quarter inch forward of the aft aerobatic CG limit and find that is the sweet spot for solo aerobatics.

The aircraft is capable of all of the maneuvers in the IAC Sportsman sequences (roll, loop, immelmann, split S, cuban 8, spin and hammerhead turns) and most competition RV pilots fly in that category. The Intermediate IAC sequences can be flown in the RV-8 but there are more negative G figures and snap (flick) rolls. Snap rolls can be done but you should become very proficient in the aircraft before you attempt snaps. I so snaps between 100 and 110 knots and have never exceeded 4 Gs during the maneuver.
If you are new to aerobatics you should get some dual instruction in spin and unusual attitude recoveries. It doesn't have to be dual in an RV. The basics recoveries are the same for most aircraft. And practice aerobatics with enough altitude to do two botched recoveries and still have enough altitude for a successful third attempt!

Van wrote a very good article about IAC Aerobatics in the RV. It's in the August issue of the EAA Sport Aviation Magazine. You can find it in the EAA.org archives if you are a member. Or you can send me your email address via private message and I'll send you a PDF of the article.
Hi Ron

No I am not all new to aerobatics, I have certificate for glider aerobatics.
Talking about spins, Vans strongly advise to never do it by purpose, but I find it most valuable to get spin recovery into the muscle memory, so I intend to do it.

I suppose G load is not fully significant when it comes to snap rolls, as the measured G load is only where the meter is, and the load is very assymetrical, so you might have a higher load on one wing. I love snap rolls and hope I can do them in my RV-8.

Yes, I have paid the EAA membership, but all has not gone through, so if you could mail me the article I would appreciate it. hans@ryrstedt.se
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  #28  
Old 07-28-2018, 12:23 PM
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ronschreck ronschreck is offline
 
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Location: Gold Hill Airpark (NC25), NC
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Quote:
Originally Posted by HansR View Post
Hi Ron
Yes, I have paid the EAA membership, but all has not gone through, so if you could mail me the article I would appreciate it. hans@ryrstedt.se
Article is in the mail.
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Ron Schreck
IAC Director and National Judge
RV-8, "Miss Izzy", 2100+ RV Hours
Track Me
VAF 2018 Donor
"He who demands everything that his aircraft can give him is a pilot; he that demands one iota more is a fool."
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  #29  
Old 07-28-2018, 09:32 PM
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RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 839
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Quote:
Originally Posted by HansR View Post
Talking about spins, Vans strongly advise to never do it by purpose, but I find it most valuable to get spin recovery into the muscle memory, so I intend to do it.
I've never seen or heard Van's advise against spins in the RV-8. There is a section regarding RV-8 spin entry and recovery techniques on page 15-18 of the RV-8/-8A Construction Manual. (In that section, it does recommend that the RV-6/-6A and RV-7/-7A limit intentional spins to two turns or less, and that the RV-9/-9A is not intended for spins at all.)

In that section it does say, "Van's Aircraft Inc. does not consider spins to be a recreational aerobatic maneuver, and recommends that they not be casually undertaken."

Page 15-23 and -24 discusses aerobatics and entry speeds for various maneuvers.

You can purchase the plans and manual on a USB flash drive for the RV-8/8A using this link:
http://www.vansaircraft.com/cgi-bin/...oduct=fd_plans
You may also want to peruse this article by Van, "An Aerobatic Epistle":
http://vansairforce.net/safety/AnAerobaticEpistle.pdf
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Carl N.
Arlington, WA (KAWO)
RV-8, 355 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflügel Standard Libelle 201B, N564NS - Sold
Rolladen-Schneider LS1-f, N61MP - No longer owned

Last edited by RV8JD : 07-28-2018 at 09:58 PM.
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  #30  
Old 07-29-2018, 04:22 AM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
Posts: 102
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Quote:
Originally Posted by HansR View Post
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.
I purchased my -8. It's pretty light at 1012# emty. I'm 6-2, 205 # and rode in the back for 8 hours home after purchasing it since I wasn't able to fly it yet. Absolutely no issues with Van's stock seats. Very comfortable. I've also done aerobatics in the back including spinning, loops and roles. My weight in the back with 35 gal in the tanks and a light pilot is about the limit. The plane is a joy to fly. I sometimes wish I had a little more weight on the nose given my FP prop, but overall, there are no issues flying aerobatics as long as you follow the specs from vans.
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Boston, MA
RV8 Based at ORH - Purchased
RV8 - The Dream - Under Construction
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