Seems that your bird was weighed with the tanks full and not empty as the procedure calls for.

Just for fun, I once filled up a Wagon when it was sitting in 3 pt attitude (long range tanks.) I then put it up into flight attitude and did and experiment to see how much more I could get in... I was able to fill it with 8 more gallons. The point is that filling up an airplane does not necessarily NET you the book numbers that will give you a proper WB.

Moving the battery does move the CG forward though. The concord is just shy of 30lbs around Sta. 110-115ish. Pull that out and then add 14lbs at Sta. -2 and it will shift it just over 1".

Hard to say other than you wont really know until you get it on the pads and follow how Cessna wants it done. Feel free to give me a call if I can help in any way.

Been following this thread. Recently put my 182C on the scales and was a little disappointed on how far the previous W&B was off. Especially since I have owned her I have done nothing but strip weight.

1960 182C - 1732 EW

PPonk
Mac 82
Skytec Starter
Plane Power Alternator
Odyssey Battery
No Vaccum
Sportsman STOL
Micro VGs
Landis Fork
Desser 8.50 mains & 8.00 nosewheel
Atlee Dodge Jump Seats
Full Selkirk interior and extended baggage
Coindot flooring
Full panel clean up with lots of wring removed.

Think Wing X is in my future to help accommodate the growing family.

gptc wrote:...Recently put my 182C on the scales and was a little disappointed on how far the previous W&B was off. 1960 182C - 1732

Seems like your 182 is set up pretty well!

This is the main point of my post here. These numbers we are finding after the "gut" work are great. I think it started back in the day with the George Mandes thread... certainly I fell victim to the hype. The 1962 185 started out with a calculated weight of 1580 lbs with the thought of 1550 after full IFR and every bush mod possible. I remember visiting Beegles when his bird was there for the work and got the bug. I too was gonna find me a Skywagon and build it as light as possible. So many of us have been there. In the end, some $650k of dieting later, the bird rolled out at 1689 lbs. Everyone was disappointed, but the fact is that a bird that well set up at those numbers was astounding.

For some reason, we all think that we can get these things to unrealistic numbers. How many times has someone posted here that they plan to drop 100lbs out of a Cessna?

I have weighed a bunch of 100 series at this point, and I have consistently found that the findings are roughly 60-90lbs heavier than the paper says. Of course the debate always arises (topic for another thread) where folks argue not to weigh the bird so you can have more useful load, but this is just silly. Ounces add up to pounds, and pounds equal performance. Work hard and smart about being weight conscious, know exactly what we are flying, pay attention to C.G., fly safe, then let all the nonsense go and enjoy! Moreover, be realistic about what weights should be, and don't be disappointed when you don't see a 1300lb number on the scale... After all, if it fits, It'll fly!

1732lbs on a 182 is awesome, especially with all the mods!

BTW... here is the 185 thread that afflicted so many: http://www.supercub.org/forum/showthrea ... 85-project

Rod, your 9/21/15 W&B looks good.
Like Greg, though, I don't like that they (supposedly) filled it with fuel then calculated the deduct for empty.
I know people who do that, but I like to drain them dry, then you know for sure.
Looks for sure like they actually plumbed down and measured the various arms, which is good.

Yours is very similar to mine in CG, although about 100# heavier.
My W&B was done after the battery was moved to the firewall though--
from the W&B calcs done at that time, that resulted in a net weight loss of about 12 pounds and moved the CG fwd 2 inches.

FWIW I just did a W&B on a buddy's PA-18-105.
Zero fuel but with 5 qts of engine oil.
I plumbed down the important points: datum (wing leading edge), MLG, tailwheel.
Marked it all on floor, then after lowering the airplane & rolling it out of the way
I snapped lines between the LH & RH WLE & MLG marks & broke out the tape measure.

TCDS says MLG is 2" aft of datum, ours was 2.2".
The arm for the tailwheel was off an inch or two (can't remember) from the TCDS also.
Just goes to show you that you should measure and verify (or not),
don't just take the TCDS (or previous W&B sheets) as gospel.
Our measurements did match a factory W&B sheet from back in the day though.
CG was comparable but the airplane had gained close to 100# since new.

Great discussion with interesting perspectives. It seems like most of the time the discussions revolve around weight and the only mention of CG is to throw the tool bag in the back if it ends up nose heavy. I recall a conversation with a C180 pilot about firewall batteries. At the time he wasn't a fan because it moves the CG forward.

I've paid close attention to weight and CG during the build of my BH; CG being the primary consideration. IMO the BH is miserable to fly with a CG aft of 21.5" (CG range 10.5-22.5) so in order to fit my intended load I need an empty CG of 11" or forward. With third row seating, 400x4 tailwheel, big windows, and too many coats of paint on the fuselage I may end up with a CG problem. Don't worry though, I've saved room on the firewall for a tool bag shelf.

Wa180 wrote:I have the ABI fork with a baby bushwheel,..

Rod, I would be curious to see what tail measurement they used on the recent calculated WB's. Your TW station was listed at 259", where as the babybush should fall at the 265 ish range. if they used the measurement for the stock TW, this could induce some errors.

The real question to ask is does she fly wonky? With just you alone and minimal fuel, she will fly really weird. It should be a crazy slow bird and you should never be able to get the hoiiz stab close to trimmed on final. If yes, then maybe it is really fwd C.G. But if its not that bad, that tells you a whole bunch.

Again, I would bet Zzz's BH project that you will find different numbers if you get her on scales.

Hey Bigrenna,

In your first post you discussed getting the cg as far aft as possible, and then having the tail working harder and stall faster as a result. That doesn't seem right. For a given weight, an aft CG counteracts the the wing's pitching moment more compared to a forward CG; with an aft CG, the tail does less work and the plane goes faster as a result of less induced drag. It should also stall slower.

Along those lines, it would be interesting to consider whether having the battery as far back as possible could be a good thing, and actually improve performance, in spite of the weight difference.

jcadwell wrote:In your first post you discussed getting the cg as far aft as possible, and then having the tail working harder and stall faster as a result. That doesn't seem right. For a given weight, an aft CG counteracts the the wing's pitching moment more compared to a forward CG; with an aft CG, the tail does less work and the plane goes faster as a result of less induced drag. It should also stall slower.

Along those lines, it would be interesting to consider whether having the battery as far back as possible could be a good thing, and actually improve performance, in spite of the weight difference.

I will have to go back and re-read... but my thoughts were on combating FWD C.G. The bird is faster w/ an aft CG, and it will stall slower, but less stable. With the Sportsman wing for example, the difference between full fwd CG and full aft CG can be as much as 8 kts difference, which is nutty.

I believe I was saying that FWD CG is bad because it will slow you down and cause the stall speed to be higher.

No problem. Just made me wonder if 5 pounds worth of extra cable to move the battery to the back is better than moving all that weight up front.

jcadwell wrote:No problem. Just made me wonder if 5 pounds worth of extra cable to move the battery to the back is better than moving all that weight up front.

I think its a good point. There is a reason Cessna put the battery back where they did.

The benefits however (IMHO) outweigh the downsides. First, the firewall battery is around a 22 lb savings once all is said and done. Take the shore power plug out as well and save another 3. And second, no battery back there allows for a flat extended baggage floor, which is very nice.

If your smart, you can mod a Skywagon to great short field benefit if your smart about it. Firewall battery, airglas extended baggage, utility interior, Sportsman, 8.5x6 Desser smoothies, lightweight panel etc etc etc and you can get it NET pretty close to the CG it rolled out of the Cessna factory... provided you can put the cash firewall forward as well. Lightweight starter, MT prop, etc. In my case, My bird is only 0.2" away from the orig CG. The late model I just delivered is actually 0.2" further aft than the orig Cessna CG. This is good...

Fact is it is all a moving target, but the good thing is it's only math. Get your bird on actual scales before you spend a dollar... A couple hours of chair mods on a spread sheet can go a long way with your planning.

Bigrenna wrote:….. In my case, My bird is only 0.2" away from the orig CG. The late model I just delivered is actually 0.2" further aft than the orig Cessna CG. This is good... Fact is it is all a moving target, but the good thing is it's only math. Get your bird on actual scales before you spend a dollar... A couple hours of chair mods on a spread sheet can go a long way with your planning.

I agree that doping out the effects of your planned mods as much as possible is a good idea, before diving into doing the work.
As far as keeping the CG where it was from the factory- maybe yes, maybe no IMHO.

Mine rolled out (supposedly) weighing 1490 with a 36.2" CG.
Today, it weighs 1652 with CG at 34.62".
Even discounting the extra poundage, it probably doesn't fly as nice as it did back then,
but the more-fwd CG does allow it to carry more of a load aft- esp handy since I have an extended baggage.

My C150/150TD had a middle-of-the-envelope CG location,
I could have moved it fwd by putting the Odyssey battery on the firewall,
but it flew so sweet as is that I didn't want to mess with it.
Plus, it wasn't meant to be a heavy hauler, so no real need.

Bottom line, like most things, the CG location is a compromise.

Bigrenna wrote: Rod, I would be curious to see what tail measurement they used on the recent calculated WB's. Your TW station was listed at 259", where as the babybush should fall at the 265 ish range. if they used the measurement for the stock TW, this could induce some errors.....

I agree.
FWIW mine measured out at 260.7" with a 10" XP 3400 series.

I'm curious...let's say I replaced that 10" t/w with a BBW.
I wouldn't want to physically reweigh the airplane for that minor change,
I guess I would calculate the new W&B by deducting the wt of the 3400 at 260.7, and adding the wt of the BBW at 265-ish?
Trickier yet with some other mods.
For example, the stock "wheels aft" MLG was replaced on my 53 model years ago.

I couldn't find a W&B sheet addressing this change,
this was one of the reasons I decided to weigh it myself.

The MLG wheels are listed at +22" on the factory W&B sheets,
whereas I measured my main wheels at 18" with the later gear.

But the gear legs themselves are not at these stations.
I guess if you had to calculate it,
you measure the arm for each end of the gear legs, and use the average for the gear leg station?
Something like this was done when calculating the wt of the original battery cable,
removed when going to the firewall-mounted Odyssey.

Greg, I never meant to imply that it flyies anything but better than I can pilot her...

Since I have a data point of 1, I think it flies fine, but was looking for a sanity check that what I was finding with W&B is what others have seen.

I haven't worked to much on lightening in front of the firewall. I got a good deal on a alternator conversion, but the goal was better charging not weight reduction. After the discussion on starters, I am not ready to change what is working well right now.

I am going to look back through the W&B history and see if I can find where they installed the BBW, and see if an adjustment can be made.

For my planned trip, we had to push it out a day, so my fat buddy can't come with us now, so it's just me and my daughter, and full fuel and ballast, and it all works out.

I am trying to track down some scales, since I cannot use the resources at school any longer. Packed up my toolbox, and had our final BBQ this afternoon, and closed that chapter... Bittersweet. Not ready to go back, but it's been 2 years of 7:30-4, 4 days a week...

This has been a great discussion, even if we drifted to specifics from generalities.

Rod

PS: My Wing-X extensions may be in a holding pattern for a bit as my daughter told us last night that she and her boyfriend are getting married at the end of the summer. My how plans change in a heartbeat!

Congrats Rod!

Bigrenna wrote:Work hard and smart about being weight conscious, know exactly what we are flying, pay attention to C.G., fly safe, then let all the nonsense go and enjoy! Moreover, be realistic about what weights should be, and don't be disappointed when you don't see a 1300lb number on the scale... After all, if it fits, It'll fly!

This sounds familiar...

My bird is bone stock and it is still a TON of fun. Fat girls need loving too.

Wa180 wrote:….I am trying to track down some scales, since I cannot use the resources at school any longer. Packed up my toolbox, and had our final BBQ this afternoon, and closed that chapter...

They won't let an alumni do a quick weigh-in on their scales?
You musta been a bad boy in class.

My neighbor's got a set of good digital scales,
I can borrow them with a little advance notice if you wanna come over here to the wet side sometime.

I’m going to get a friend and measure things tomorrow, and see how that plays out using the weight that they got, but possibly a new arm for the baby bushwheel. I have access to scales, but school is out for a couple of weeks before summer session starts.

Our program was open entry / exit, and I was one of two that got licensed this quarter. It blows me away how many people go through the whole program and then don’t get their licenses.

Rod

Bigrenna wrote: ...The only rub is the cost of the Stabs as they are getting really rare. Also, you will most likely need the 3 bolt stab rather than the more common 4 bolt. They were $6-$8k the last time I priced one for a customer.

With the price going up, it might be worth considering modifying the existing fin into the larger style. SK180-33A has the plans for doing it. A few parts/skins would need to be fabricated, but if you have the skills, it's probably not that hard.

Chris

I am trying to figure out what the larger fin is doing for you in that scenario.

Wa180 wrote:...possibly a new arm for the baby bushwheel.

The only real way to know is to measure. This discussion had me go back thru the sheets on a couple of other birds. I have records of everything from 257.5" to 264.5" with Stock 3400, to XP, to ABI forks. Even different measurements with the same forks. The 264.5 # I gave may be on the long side since it was the longest I saw in my paperwork. There also might be a difference because of tail springs. 7/8 vs/ 1 1/8. New vs worn... Tweaked spring vs/ perfect...Who the heck knows really. But keeping to my original point, these minor differences wont change things a huge amount inthe grand scheme of things.

For example, I looked at the shortest TW measurement I had which was 275.75 (see pic below) . The top is the weight I had. But if I extended the TW out 5 inches aft the NET result is moving the CG aft only 0.37". Of course its really important to get these numbers correct, but if you are off by 0.25" its not the end of the world. Just make sure its in flight attitude when you plumb it to the floor. This is measured on the upper door sill. You may even get different measurements putting the level on the rivet heads va/ off, so pick wisely.

I think we have all spent more time collectively thinking about this than the Cessna Mech when they originally weighed the birds, so with a grain of salt...



RE: measurement... The firewall is easy as you can just drop a bob to the floor, where as the TW is much more difficult to be exacting since its sitting on something up in the air. Make sure you have a long enough tape (at lest 25')

FWIW... I use an HVAC elevator to lift the little wheel. It makes it super easy to get the digital level perfect since the elevator makes really small adjustments.