Weight and Balance

[bob turner]

Some friends just got weighed. Gained 100 lbs, which reduced their useful load to below 400#.

Now they own a single place 7AC.

There is nothing wrong with weighing an aircraft, but it is not required by any regulation I know of. If you overload an aircraft, say by taking your 120 lb kid and a full tank of gas aloft, your insurance may not be in effect. Yow!

My theory is that in the days of Cubs and Champs, the factory was cheating. Otherwise, I have no idea where this extra 100 lbs comes from.

[Paul Agaliotis]

Bob,
I think you're right. Most of these little planes have become a little heavier over the years. My guess is that a sample weight was done and all of the planes after used its empty weight. Any options were added on paper.
We do the same thing at work. When we add and subtract items to the 747's we don't weigh each aircraft. We do a sampling of the fleet and that weight is used for flight planning.
Paul

[rkittine]

I know from experience on my Aeronca's, looking through the logs, the weight was ever increasing as carpet was added, instruments were added, panel cover, new seat cushions, antennas and other things. A real stripped down version as it left the factory probably was the weight claimed as they are certificated aircraft. Then of course you put yourself in (dressed which adds a few pounds to what I claim to be my weight! ), fuel and also headsets, the GPS, Hand Held Radio, extra oil and maybe batteries, lunch, etc. and you are even farther up there. One of these days I am going to weigh my planes as currently equipped and see where they stand. Should be interesting. (probably have 5 pounds of dirt after sitting in the hanger most of the winter)

Bob

[MikeB]

I've never weighed a Champ at less than 800#. We have a stripped and pretty 'plane Jane' (pun intended) on our field and it came in at around 820# . Newer fabric process seem to add more weight for example although the one I'm describing had dope and not much of it. Currently undergoing restoration so be interesting to see how it comes out with new Poly-tone on it. My L16/0200 weighs around 950# but has a starter and Concord battery, interior, metal prop, Superflite covering process, .022 leading edge rather than .016, .032 new ribs, wing tanks, etc. etc. It all adds up. If you throw it up and it comes down it's going to add weight. Fortunetly, I'm pretty light at 160# so weight isn't really a factor unless I add a passenger then I have to watch the fuel somewhat.
Mike

[Champ Dreamer]

When re-doing my Champ, I paid very close attention to weight. New polyfiber system, no carpet or upholstery on side panels. Wood prop. Anything that was not necessary was removed. I added a Flight line radio (very small), C-85-12, Odessy battery and Skytec starter. It weighed 838#, bone dry, on certified scales. I am very happy with that. The airplane performs very well with me (175#) and a passenger of the same (or preferably less weight) at densiuty altitudes up to 9,000.

Brian Walker
7AC/DC

[bob turner]

Of course they perform ok - they were doing that before we started weighing them.

If your trim sheet says 838# and you add two 175# folks, you are sitting at 1188 before adding fuel. I do not know the 7ac gross weight number, but I am betting that leaves you enough room for one time around the pattern plus VFR reserve fuel.

Had you computed instead of weighing, the thing would perform the same, but now you are flying legally. That was my point.

[MikeB]

I looked at a Champ at Oshkosh once that had a C85, wing tanks, full interior, metal prop, etc. and the information on the prop said something like 800#........ hmmm . The Wagner STC on my L16 does raise the GW to 1300# rather than 1220#. According to the STC, it technically (because it has the no-bounce gear) it could go to 1350# but I chose to leave it at 1300# to keep it at light sport. With the 0200 performance is not a problem.
Mike

[jepropst]

I have a bit of a concern in reading though this thread, that someone may get the impression that having accurate weight and balance data is not important and that it is OK to push the weight limits, especially with some of the increased power options.
While these aircraft may be somewhat forgiving when pushing the weight limits, they are not necessarily forgiving when exceeding the center of gravity limits. As we increase the weight due to various fuel and power options, we need to understand that the CG limits still begin to narrow as the weight exceeds 1087 pounds. These little planes can be safely flown with the various weight increasing options, but you need to accurately know the CG limits before you leave the ground and also know how the CG limits will change as we burn the onboard fuel.
I personally have run dozens of W&B scenarios with various fuel, passenger, and luggage options for my plane. I know that there are certain combinations that I must avoid to assure that I do not exceed the CG limits.

[MikeB]

Good point, John. As I'm not home I don't have my weight and balance sheets right in front of me but my L16/0200 tends toward the 'nose heavy side' with only me in the plane although within the CG specs. I never expected it due to the fact I have a 24 pound Concord battery behind the rear seat. I thought that if anything I would be leaning toward the 'tail heavy side'. Didn't work out that way, though. The 0200 is a few pounds heavier than the C85-12 but I have the Sky-tec starter rather than the heavy Delco and the short mount rather than the long. Metal prop hanging way out there is another factor but I think the big difference is the 13 gallon nose tank. A better setup is probably removing the nose tank and installing the 13 gallon wing tanks. My friend has basically the same aircraft with the 13 gallon wing tanks and is within a few pounds EW as mine but his W & B is more 'balanced' if I remember correctly. I have the 5 gallon wing tanks which doesn't seem to be much of a factor (CG wise) other than adding additional weight. At the present time I have no charging system but have received field approval via 337 for installation of a B & C alternator which would add a few more pounds forward. To be decided when I get home and work things out.

Champs I have flown seem to be a bit on the nose heavy side and won't exactly 'trim for landing' which isn't necessarily a bad thing but you do need to pay attention so the air speed doesn't creep up on approach.

Suppose I could fly from the rear set but then folks would surely think I have a Piper Cub .

Mike

[bob turner]

Guess I haven't flown enough Champs. While not Cubs, they are way ahead of whatever is in third place. Never a trim problem.

Look - there is absolutely nothing wrong with weighing your aircraft. It is simply against regulations to operate it above the gross weight limits. It is not illegal to compute your weight and balance, and if your official paperwork is properly done, you might be able to haul two adults and gas.

But what is happening is that folks are dutifully weighing their airplanes, and then deliberately putting two adults and fuel in them - I am guilty too, because otherwise I could not instruct in about half the J-3s and J-4s out there. The most recent was a Cub with 401 lbs useful load. What can you do with that? You can get in a ton of trouble, even if you just have a flat tire and tie up a runway.

Now the Champ I taught three folks to fly in can no longer be used for a trainer, unless both instructor and student are child- like in stature, or unless the instructor ignores the W/B.

[MikeB]

As John indicates above, the CG narrows considerably as you exceed 1087 pounds. My 0200 equipped L16A has a GW of 1300# with the Wagner STC but I run on the 'ragged edge' of the CG with just me in the aircraft (which is 90% of the time) and tends to the nose heavy side although it's not really a bother (makes beautiful wheel landings ). Putting someone in the rear seat changes that of course but my useful is pretty limited. I still maintain the 13 gallon nose tank is probably the culprit. I suppose a 775# Champ with a A65 and wood prop in 'stock configuration" might be different. I've run several different CG accounts for my own information and they all seem to come up about the same.

Mike

[Jerry Eichenberger]

Didn't someone say a while ago that when the Champs were built, the factory used only 3 coats of dope - one clear, a silver, and one coat of color? Wood props, really skinny seat cushions, and no fabric carpet or trim anywhere in the interior except for the headliner - all made them a lot lighter than what folks are doing now.

[CF-KYE]

I have a 7CCM that has basically been converted to a 7EC (electrics, long engine mount, no nose tank) but after not flying her for a couple of years (and me putting on some weight that I'm now trying to get rid of) I can't make a power off, three-point landing anymore. I had gotten into the habit of carrying just a little power through to touchdown and it will three point that way. Looking at the weight and balance for the Champ it looks like a pilot's increased weight and any increased fuel load (no nose tank, 39 USG wing tanks) should make the airplane progressively more tail heavy not nose heavy, but that doesn't seem to be the case. I'm just rechecking the elevator travel and cable tensions now but if that checks out I'll have to re weigh her and see where her empty C of G lies. I was planning on going back to the short engine mount anyway and that'll help. I'd hate to have to add some ballast back in the tail.

Dan
7CCM-141
CF-KYE
ex N4576E