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  #1  
Old 07-31-2018, 10:59 AM
Tankerpilot75 Tankerpilot75 is offline
 
Join Date: Jan 2015
Location: Oklahoma City, OK
Posts: 308
Default Yes, Iím stupid but lucky

This yearís trip to AirVenture taught me a valuable lesson about C.G. And weight.

Like (I suspect) several RV owners I became complacent about cg and weight because these planes perform so well. Background: my RV7A is a little heavy to begin with due to a nice panel, oxygen system, lovely interior, pretty paint job and a few extra luxuries I consider important to always carry. In other words the basic empty weight is 1,188 lbs. My empty C.G. is 79.97 which is a good forward cg.

Last year I overloaded the aircraft by about 100 lbs. and had absolutely no problems. This year was different! Iíve personally gained 5 lbs., my passenger was a little lighter than last yearís passenger; so I put about 125 lbs in the cargo area and estimated my total gross weight around 1,950 lbs. Takeoff cg was within limits.

I was part of a two ship arriving Saturday night and when three minutes out of Ripon they closed Oshkosh ten minutes early. We diverted to Appleton. Landing at Appleton was stick sensitive but very controlled.

My lead flew to Oshkosh the next day (3.5 hour flight plus one fuel stop) while I elected to stay at Appleton since it was convenient and my parking fee for that Saturday night was the same as the whole week. I was also told OSH HBP was muddy so staying at Appleton just made sense. I had room reservations at Oshkosh dorms and took the bus to AirVenture.

Like a lot of folks I purchased a few things, picked up a few more ďfree goodiesĒ and so did my passenger. Return trip on Friday added another 10 to 20 lbs aft. Our return trip had me stopping at North Central Regional (MO8) for fuel. Unfortunately they ran out of 100LL two planes before my turn (price $3.90 gallon). We still had 18.5 gallons so I flew on to Marshall Memorial (KMHL) an additional 20 minutes air born for fuel. This burned about four gallons more. Airplane felt unusually sensitive with a slightly nose high pitch on this flight.

My first landing at Marshall surprised me with severe PIO (never have I experienced this before) so I went around. My second attempt was even worse. Now Iím shook up! (Iím a 3,800 hour - long retired military instructor pilot - and PIO is something only rookies experience - right?). My passenger (a former Tora Tora pilot and Reno Air Racer calmly suggested I apply full nose down trim - which I did. Thankfully it worked and the third attempt resulted in no PIO and a safe landing.

Lessons learned:
1. Donít become complacent. Play attention to cg limits and gross weight. While you can be within cg limits on take off, inflight fuel burn will move your cg aft. If already over weight this can get you into serious trouble if your cg at takeoff is near the aft limit.

2. Use FedEx or UPS if you suspect your overweight. Even better - donít start overweight and expect to not have consequences. Itís cheaper to mail stuff than to damage the aircraft and possibly hurt someone.

3. If you find yourself trying to land your RV outside of aft cg limits - apply full nose down trim! It will keep your nose down and help prevent over controlling the aircraft as you try to make a landing. Remember an aft cg makes these aircraft extremely sensitive to control inputs. Full nose down trim dampens this out a little.

4. Make sure your lighter passenger deplanes first and have him/her hold the nose down while youíre getting out. Fat boys on the rear step will cause the tail to drop. We at least thought of this before deplaning.

I share this with you in the hope that youíll pay more attention to cg and weight limits when you make a long trip. These airplanes are great little performers but they can make you complacent if youíre not careful. Remember ďfull nose down trimĒ can help reduce PIO when control forces feel too light.
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Jim Harris, RV7A, 2nd owner, N523RM
IO-360, Hartzel CS prop, Older Aerotronics built panel Dual GRT Horizon WS, Garmin 340, 335, Dual 430s, Stratux hard wired to WS, Dynon D10A (backup EFIS)
Retired - Living the dream - And going broke!
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  #2  
Old 07-31-2018, 11:36 AM
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Brantel Brantel is online now
 
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Location: Newport, TN
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People poke fun of me shipping our support gear up to Osh and back home on departure. My 7 is 1.27" aft of the fwd limit empty so this is the hard limiter for my baggage compartment.
Let them poke!

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Last edited by Brantel : 07-31-2018 at 11:42 AM.
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  #3  
Old 07-31-2018, 11:44 AM
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erich weaver erich weaver is offline
 
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Location: santa barbara, CA
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Great post Jim. Thanks for the tips!

erich
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  #4  
Old 07-31-2018, 12:25 PM
fixnflyguy fixnflyguy is offline
 
Join Date: Jan 2006
Location: Winston-Salem, N.C.
Posts: 935
Default Worse in tandems

I cant agree more, the effect of CG with fuel burn, and in a tandem (I have a -4) it can get even worse. If I'm even close to an AFT CG loading, I make sure I don't have to land with much less than 1/3 fuel remaining. Big difference when they are near empty. I too use additional down trim for the same reason, and also to negate pitch up if you have to throw the coals to it and do a go-around.
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  #5  
Old 07-31-2018, 12:26 PM
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Planecrazy232 Planecrazy232 is online now
 
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Quote:
Originally Posted by Brantel View Post
People poke fun of me shipping our support gear up to Osh and back home on departure. My 7 is 1.27" aft of the fwd limit empty so this is the hard limiter for my baggage compartment.
Let them poke!

I won't poke- we did the same thing shipping up 150 pounds of stuff. My wife saw empty spots in the boxes and filled them up!
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RV6-A "Aluminum Mistress"
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  #6  
Old 07-31-2018, 12:32 PM
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Mark Dickens Mark Dickens is offline
 
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Location: Collierville, TN (KFYE)
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The first time I took a passenger in my -8, I got a real wake up call with the pitch sensitivity on landing. I run a weight and balance for any time I have anything in the back of the plane. I was used to flying certificated planes and this really got my attention. It is a different plane with someone in the back!
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  #7  
Old 07-31-2018, 12:48 PM
Kyle Boatright Kyle Boatright is online now
 
Join Date: Aug 2005
Location: Atlanta, GA
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Especially in the side by side airplanes, you can move luggage to right in front of the main spar in the footwell or ask your passenger to hold a bag in his/her lap (assuming the stick is out) and move the CG substantially forward.

Any time I am near aft CG I do one or both of those things.
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  #8  
Old 07-31-2018, 01:25 PM
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airguy airguy is offline
 
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Location: Garden City, Tx
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Quote:
Originally Posted by Planecrazy232 View Post
I won't poke- we did the same thing shipping up 150 pounds of stuff. My wife saw empty spots in the boxes and filled them up!
OK, so where are you guys shipping to at Oshkosh? This sounds like a good avenue...
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Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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  #9  
Old 07-31-2018, 01:26 PM
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Brantel Brantel is online now
 
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Location: Newport, TN
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Quote:
Originally Posted by Kyle Boatright View Post
Especially in the side by side airplanes, you can move luggage to right in front of the main spar in the footwell or ask your passenger to hold a bag in his/her lap (assuming the stick is out) and move the CG substantially forward.

Any time I am near aft CG I do one or both of those things.
I do this as well. My tool bag goes on my side and my tiedowns and hammer go on the co-pilot side. Never even notice that they are there. Keeps a good bit of weight in front of the spar!
__________________
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Working on Emp/Tail Cone
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
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  #10  
Old 07-31-2018, 03:35 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
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Quote:
Originally Posted by Brantel View Post
I do this as well. My tool bag goes on my side and my tiedowns and hammer go on the co-pilot side. Never even notice that they are there. Keeps a good bit of weight in front of the spar!
I was wondering about doing this, thanks for the confirmation.
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RV-7
1st Flight 1-27-18
Phase II 8-3-18
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