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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: 810
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: 8
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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
Posts: 64
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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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RV-8 N88MJ (Built by Michael Robbins)
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  #24  
Old 07-04-2018, 04:34 AM
ronschreck's Avatar
ronschreck ronschreck is offline
 
Join Date: Mar 2006
Location: Gold Hill Airpark (NC25), NC
Posts: 1,305
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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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