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Yes, I?m stupid but lucky

Tankerpilot75

Well Known Member
This year?s 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! I?ve personally gained 5 lbs., my passenger was a little lighter than last year?s 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 ?free goodies? 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 I?m shook up! (I?m 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. Don?t 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 - don?t start overweight and expect to not have consequences. It?s 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 you?re 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 you?ll 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 you?re not careful. Remember ?full nose down trim? can help reduce PIO when control forces feel too light.
 
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!

:p
 
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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.
 
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!

:p

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!:eek:
 
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!
 
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.
 
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!
 
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.
 
Great reminder TankerPilot. Thank you for sharing. It's really nice to know that even Pilots with tons of hours can admit complacency or a just plain forgot after so many years the importance of remaining within W&B.

:)
 
Absent a read of a thread like this, I bet one does the aft but legal CG thing one time and then comes up with the right solutions.

I also did the tool bag and tie downs in the center of the foot well trick this year to OSH (need to install some hooks and procure some elastic webbing to make it safer). Then, we flew up high on the return, so it was "Honey, is that an O2 bottle between your legs, or are you just happy to see me?" :D
 
This is a great thread. Thanks for sharing.

With respect to fuel burn, it is my understand that all weight added to the RV10 at least (I'm not sure of the others) moves CG aft. Burning fuel in that case should move the CG forward n'est pas? If starting close to aft limits then fuel burn should not pose a problem unless of course one burned enough to bring CG past the forward limit (I don't even know if this is possible with the 10 at least).
 
This is a great thread. Thanks for sharing.

With respect to fuel burn, it is my understand that all weight added to the RV10 at least (I'm not sure of the others) moves CG aft. Burning fuel in that case should move the CG forward n'est pas? If starting close to aft limits then fuel burn should not pose a problem unless of course one burned enough to bring CG past the forward limit (I don't even know if this is possible with the 10 at least).

RV-10 CG moves Aft as fuel is burned. Until I put a lighter battery in back, with my family and 100 lbs of baggage, I was at aft CG limit at 25 gallons remaining.

With some changes I am fine all the way to zero fuel.

Just checked, burning all 60 gallons moves CG aft 1 inch
 
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RV-10 CG moves Aft as fuel is burned. Until I put a lighter battery in back, with my family and 100 lbs of baggage, I was at aft CG limit at 25 gallons remaining.

With some changes I am fine all the way to zero fuel.

Just checked, burning all 60 gallons moves CG aft 1 inch

Ok. I'm not trying to thread drift but fuel has a positive moment for the RV10. How can burning fuel move CG aft?
 
I use the front floorboard quite often when hauling my kiddos, they don?t need the foot room and makes staking and packing easier.
 
RV10

Yep. With the 10 you must check LANDING CG, as well as takeoff.
Start with cg near aft limit, cg moves further aft as you burn gas. But start with cg near the forward limit, cg moves forward as you burn gas!
 
Jim
Interesting post. Informative and will probably save some lives in the future.

We have a 9A similarity equipped as your 7A, except for the oxygen. 180 hp IO-360 with MT 3 blade prop.
I believe our baggage compartments are similar in size. Our wings are different and we only hold 36 gallons of fuel.

Just returned from Oshkosh and took my first timer 13 year old grandson.
We camped in homebuilt camping.
One comment and a question.
Whenever I even suspect I might be aft heavy, I increase all my low speeds 10% (takeoff, landing, maneuvering, stall). This I learned from flying my aerobatic One Design cross country with a loaded baggage compartment. Even in that plane, not sure if I could recover from a tail heavy spin.

And unless you?re carrying some gold or other metals, how do you get 150 pounds of baggage in that small compartment?
I think we were around 80 pounds of camping stuff, spare clothes, little food and water, and body washing materials. Luggage compartment was full right up to the shoulder harness wires.
Will be interesting hearing your manifest.
Once again, great post.
Jack
 
Whenever I even suspect I might be aft heavy, I increase all my low speeds

I think we were around 80 pounds of
Jack

Wrong.
Whenever you even suspect you might be aft heavy, or you ?think? you have about 80 pounds in the back, you don?t takeoff. You unload everything, weigh it, put it back in, measure the arm with a tape measure, and calculate the cg. ?Suspecting? or ?thinking? is just ignoring your PIC responsibilities.
 
Wrong.
Whenever you even suspect you might be aft heavy, or you ?think? you have about 80 pounds in the back, you don?t takeoff. You unload everything, weigh it, put it back in, measure the arm with a tape measure, and calculate the cg. ?Suspecting? or ?thinking? is just ignoring your PIC responsibilities.
Bob
Text book, you?re absolutely correct.
Real world, I?m not sure how many pilots would do a complete weight and balance if they suspected they were marginally out of balance.
Yes, if I knew I was definitely loading 150 pounds in my baggage compartment I probably would do a W and B.
Without sounding cavalier, it?s probably the North Atlantic ferry pilot in me talking when we were always a little tail heavy with fuel in the rear ferry tanks on departure. Had no choice, so airspeed was critical, and extra airspeed was your friend.
Lots of stories that I will never print!
Thanks for the well founded advise
Jack
 
Jack
It’s not hard to put 125 to 150 lbs. in the back. First you start with a few tools for that “emergency repair.” Then you add your tie-down kit and a small ice cooler for cokes, bottled water and snacks. Then you load two soft sided bags full of cloths (only half which you really need). Then a back pack full of shoes, flip flops, dobb kit, and other truly wonderful stuff. Finally you top it off with a couple of pillows because you know the dorm pillows suck and another small bag of inflight snacks and water.

Now to answer the other question - I did do a weight and balance for takeoff weight and was within balance. But I didn’t look at landing cg. When I re-looked at this situation Sunday afternoon on my computer I realized my RV went aft of my cg limit somewhere around 24 gallons of fuel onboard. When I landed at North Central Mo. the aircraft felt a little light on the controls (18.5 gallons) but behaved okay. My troubles began on the leg to Marshall field and the burning of an additional 4+ gallons. By this time my cg was noticeably too far aft (about 1/3 to 1/2 inch) because of the amount of trim required to keep level flight for the speed I was flying. The aft cg condition really manifested itself on landing (yes, I was carrying an extra five knots due to weight) when just a very slight flair resulted in severe PIO with the aircraft bouncing from mains to nose to mains to nose etc. Immediately I went around and with the second attempt much like the first I realized I was in serious trouble. It was the recommendation of my passenger of applying FULL nose down trim that allowed me to safely land on my third attempt. This helped keep the nose down and gave the controls some badly needed feel.

I was lucky. First because the severity of the PIO didn’t result in any damage to the aircraft. Second, because I had a very experienced copilot/passenger who knew how to handle aft cg aircraft and keep cool under trying conditions (remember I mentioned his Tora, Tora and Reno Air Race experience). It seems that when he did that type of flying he often flew near aft cg limits because of the extra maneuverability that condition provided in competition.

Yes, I have a number of flying hours but 98% of that was in military jet aircraft (not light pistons) and over 26 years ago. I’ve only been back to flying for four years and at times still feel like a rookie when caught with my pants down like the return flight from AirVenture. Experience is a double edged sword. It helps you learn from your mistakes, it gives you the ability to recognize the cause of those mistakes, it sometimes gives you the ability to prevent a mistake from getting worse, and if your attentive - it can prevent you from making a serious mistake. However experience will get you in trouble when you ignore the obvious because you’ve gotten away with that poor judgment call before.

We use to say, “you’re given two bags when you start flying. One is “luck” and the other “experience.” Hopefully your “luck bag” is full so when you survive a near disaster you can transfer that knowledge to your bag of “experience.” Someday your bag of “luck” will be empty and hopefully your bag of “experience” will be full and pull you through your next adverse situation.”

At my age luck has been tested quite a few times and I can only hope I’ve saved enough experience to get me through the next gotcha. I post my own “experience” to help someone whose bag of luck isn’t quite as full as mine has been. We use to call that “hanger flying” or “there I was” flying. Use of hand gestures required!
 
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This is a great thread. My rocket gets quite tail sensitive aft loaded. We all have to consider a worst case scenario where we are aft loaded, landing with low fuel and engine out. Higher landing speeds will be required.

Thank you for posting your experience
 
One thing I've done with the last few airplanes is have a W&B spreadsheet that also calculates a zero fuel condition. Hope I never have to actually land at zero fuel, but it's a good SA tool.
 
Tankerpilot,
Thanks for sharing this simple, but excellent lesson. Those of us without that (long past) military experience might not have the wisdom and humility to do so. If we are smart enough to listen, we will find our ?experience bag? a little fuller today.
Peter

Yes, I have a number of flying hours but 98% of that was in military jet aircraft (not light pistons) and over 26 years ago. I?ve only been back to flying for four years and at times still feel like a rookie when caught with my pants down like the return flight from AirVenture. Experience is a double edged sword. It helps you learn from your mistakes, it gives you the ability to recognize the cause of those mistakes, it sometimes gives you the ability to prevent a mistake from getting worse, and if your attentive - it can prevent you from making a serious mistake. However experience will get you in trouble when you ignore the obvious because you?ve gotten away with that poor judgment call before.

We use to say, ?you?re given two bags when you start flying. One is ?luck? and the other ?experience.? Hopefully your ?luck bag? is full so when you survive a near disaster you can transfer that knowledge to your bag of ?experience.? Someday your bag of ?luck? will be empty and hopefully your bag of ?experience? will be full and pull you through your next adverse situation.?
 
This +1

One thing I've done with the last few airplanes is have a W&B spreadsheet that also calculates a zero fuel condition. Hope I never have to actually land at zero fuel, but it's a good SA tool.

My son and I did a week long trip to San Antonio in the RV-7 a few years ago. Lots of bags and stuff (including a birthday cake). About 1900 T.O. weight. Worked the spreadsheet ragged and determined that:

a. Sons laptop bag would travel under his feet just fwd of the spar.

b. Absolute min fuel at landing was 18 gal.

Both of these were to keep the c.g. well within the envelope.
 
One thing I've done with the last few airplanes is have a W&B spreadsheet that also calculates a zero fuel condition. Hope I never have to actually land at zero fuel, but it's a good SA tool.

my MGL EFIS does this for me, and presents it in a great graphical format showing 3 x's for full fuel CG, current CG based on fuel sensors, and empty CG. This makes it easy to run a quick check anytime I'm flying with any substantial luggage.

EnigmaWBsmall.jpg


I also keep a tiny digital scale made for luggage in the plane similar to this, and it's only 7 bucks.

https://smile.amazon.com/AmazonBasi...3149637&sr=8-6&keywords=digital+luggage+scale
 
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Foreflight?s weight and balance feature automatically calculates the zero fuel condition and provides a warning if it?s out of the envelope. The following is a sample loading on an RV-6A.

2a5x2lf.png
 
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.
It would be great if a company like Bison Mountain would make a triangle-shaped bag that could go in this location, to help contain the items up there. You could lock it in place with a flap that extended up over the top of the spar and used the screws holding the floorboards down. I bet Bison could sell as many of these as they do the behind-the-seat bags.

Until I have those, I find my behind-the-seat bags are the best way to get weight forward... All the heavy stuff goes in them! Or at least as much as I can fit. Then all the next heaviest stuff goes behind them, and so on, until the pillows are packed against the rear baggage bulkhead. That's been enough to keep me *just* at the aft stop when travelling with a passenger and camping gear.

The first time I landed low on fuel and fully loaded, was the first time I had to use forward pressure on the stick while flaring to land... It was a little disconcerting, but I got lucky too and happened to get the flare just right and only hit the ground once... only a little more firmly than I expected.
 
Other Aft CG Considerations

I may be stating the obvious but there are other issues to be concerned with when at or beyond the aft CG limit besides pitch sensitivity.

Stall speed will be lower which sounds like a good thing but, because of the pitch sensitivity, it is easier to stall in the final turn etc since you will get more alpha with less force. And if you do stall it may be harder to recover and easier to depart.

Some of the above factors are why the aft CG limit for aerobatics on the -7 is 2.3" forward than for "normal" flight.

I have had my RV-10 at the aft CG limit and it is easy to over control in pitch, especially ballooning in the flare. I always double check the weight in balance when I know I am close to the aft limit with zero fuel (worst case). I keep a scale at the airport to weigh people and luggage if have a full load to make sure I have the weight in the right places (people and luggage).

I was fortunate enough to fly the Calspan variable stability Lear Jet and play with the lateral, longitudinal and pitch stability as well as pitch force per g, control "slop", atencyl, etc. It was amazing how quickly you could lose it and hit the limits in some conditions when transitioning from straight and level to a high gain tracking task. Neutral or negative pitch stability is eye-opening!
 
Time to fess up

I have had to be very careful, because of the c/g, that the heavy rear weight causes the plane tail to tilt such that it hits ground and damages the real tail fairing. Have had to do some fiberglass repair and paint more than once.
 
Old thread but good to study

Re-read this thread after "hauling a load" in the 9A recently. Got a good deal (as in free) on some lithium batteries in CA. Wanted to haul as many home as possible. So, I packed a tall backpack like a human... stuffed to the gills with batteries. A few more stowed down by pax area footwell. Remainder in the baggage area. Probably 75 lbs. worth. It flew fine, and I did not think too long about what a load of lithium would be like in a forced landing!
This Oshkosh scenario is a good one to think about. Fedex ground is cheap, compared to a landing ding. Maybe pilots will chime in about where to ship their gear. Maybe Basler, the FBO would accept packages, if you go and buy some fuel during the show.
 
Shipping freight to Airventure

C/O GES
Wittman Field
EAA Convention Site
1001 W Waukau Ave
Oshkosh, WI 54902 USA

There are shipping labels available on the EAA website - Airventure - Guest services.
 
OK, so where are you guys shipping to at Oshkosh? This sounds like a good avenue...

You can ship a box of stuff (camping gear, chairs, air mattresses, laundry, etc) to yourself to arrive at Oshkosh prior to the show. Shipping Services usually sets up in a shipping container placed near the main entrance. When you arrive with your much-lighter airplane, the welcome vans will be happy to drive you over to Shipping Services to pick up your stuff.

https://www.eaa.org/airventure/plan-your-eaa-airventure-trip/guest-services/shipping-services
 
I have 7A with O-320. Because of this smaller engine hanging up front I have to use caution when loading up with 2 and some weight in the baggage area. I do weigh everything and will routinely place something small/heavy forward of the spar beneath my legs and my passenger as well. If I'm flying alone there is usually a big bag strapped in the passengers seat. According to my W/B app, I would be getting close to aft CG with passenger and baggage as the fuel buns down.
 
Those floor step bars Anti Splat sells would make great anchor points for securing 'front of spar saddle bags'. Maybe Anti Splat could come up with a product like that too.
 
Interesting Read. Thank You!

Thank you for sharing.

Yes, found myself re-learning flying in the RV-6. Interesting differences between a Mooney, Piper and Cessna aircraft and my RV-6.

Best regards,
Mike Bauer
 
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