CTSW Weight & Balance

[artp]

These are my CTSW W&B numbers:

Lbs. Inch
Empty Weight 772.1 12.52
Fuel 000.0 11.81
Pilot 000.0 20.47
Passenger 000.0 20.47
Baggage 000.0 42.91

The data points for the envelope are:
Lbs. Inch
804.83 13.62
992.25 13.27
1323.00 15.04
1323.00 18.82
804.83 18.82

What this means is you have to pay attention to the center of gravity on this plane. If you want to fly with full fuel you must carry ballast in the luggage compartment. You will need between 24 pounds of ballast in the luggage compartment with 120 pounds in the front seat and 28 pounds of ballast in the luggage compartment with 325 pounds in the front seats. On the other hand if you only carry 21 gallons of fuel and have at least 120 pounds in the front seat you can load up to gross without worrying about the center of gravity. This will however reduce you range to 3 hours (330 nm with no wind) with 1 hour reserve.

[Cub flyer]

I'd compare this to other similar equipped CT from different dealers.

Maybe it was not level when weighed?

Could be the nose gear scale was not correct. (too heavy). did they check that it returned to zero after weighing the airplane?

Could be a math problem in the beginning?

the different parachute can used now is throwing things off?

Any changes to the engine mount/ nose gear?

Or just nose heavy as designed. A 172 and Tripacer with no fuel is outside the forward limit or very close but the tanks are behind the CG so adding fuel makes the CG go aft.

I'm surprised because the glass panels should be lighter and with the changes to the balance tab, vertical fin and Stab balance the CG should go further aft.


I think what we are missing here is if I spend 100,000 on a new Mercedes it will be an unbelievable machine. Nearly perfect.

The new LSA airplanes are essentially hand built and the options allow the buyer to configure them in many ways.

This is bad because there are so many potential faults with custom harnesses, options, and airplanes being reassembled by dealers. Many of whom are not real experienced with their products yet. But same price as the Mercedes above.

The Mercedes auto has a lot more moving parts and complex systems than a LSA but every aspect of assembly is controlled. They arrive complete on the dealers floor and have been tested.

LSA does not have the volume or man power to have a person specialize in each assembly task. So everyone does the best they can but errors will creep in.

That said there is no excuse for not updating airplane specifications to reflect what they actually will do. And none for releasing an airplane that has faults or inaccuracies. That's what checklists are for.

This should be a function of the LAMA audit program but I'm afraid it is only a pony show. Any airplane manufacturer with any credibility should pass the LAMA audit before a SLSA production certificate is issued.

Nobody else is looking.

[artp]

something seems way wrong here.

most of us find that there is no practical way to load our ct's and not be within cg limits.

i fly full fuel solo, without anything in the luggage compartment all the time.

As planes evolve they change. Mine was built in July of 2007. It is what FD calls one of the advanced design CTSW models. With the advanced model you either pay attention to the CG or you assume the documentation that the FD engineers who published the envelope didn't know what they were doing. If you assume the latter then you are in real trouble because you can't redefine the envelope yourself.

You have my numbers so feel free to compare them to yours and see what my have changed.

[CharlieTango]

...What this means is you have to pay attention to the center of gravity on this plane. If you want to fly with full fuel you must carry ballast in the luggage compartment. You will need between 24 pounds of ballast in the luggage compartment with 120 pounds in the front seat and 28 pounds of ballast in the luggage compartment with 325 pounds in the front seats. ...

sounds wrong, but a good job at bashing the ct again.

i ran your numbers and find you can be within cg limits with no luggage/ballast, full fuel and 252lbs for pilot/passenger and gear.

your 120lb example isn't very real world.

[Super Cub]

After looking at the pictures of the CT flyins at McMinnville and Page, I

would be real surprised if the pilots and passengers weighted in at 252

pounds or less? Most of them anyway.

[artp]

sounds wrong, but a good job at bashing the ct again.

i ran your numbers and find you can be within cg limits with no luggage/ballast, full fuel and 252lbs for pilot/passenger and gear.

This is what I get when I use your numbers:

Empty 771.4 12.51 9650.214
Fuel 198.0 11.80 2336.4
Front 252.0 20.50 5166
Baggage 000.0 43.00 0
1221.4 17152.614 14.0434

The weight is 1221.4 so the CG must be no aft of 14.56”. It is only 14.04”. You will have to add 28 pounds in the baggage compartment to bring the weight to 1249.4 and the CG to 14.69”, which is in the envelope.

Using my example of a 215 pound pilot flying solo the calculations are:

Empty 771.4 12.51 9650.214
Fuel 198.0 11.80 2336.4
Pilot 215.0 20.50 4407.5
Baggage 000.0 43.00 0
1184.4 16394.114 13.8417

The weight is 1184.4 and the CG is a 13.84. The forward limit for CG at that weight is 14.35 so I am not in the W&B envelope.

If I add 26 pounds to the baggage compartment the weight is now 1210.4 and the CG is 14.468 which is in the envelope for that weight.

I now realize that to you CT bashing is saying anything about the CT that you don’t like. It doesn’t matter to you if it is are true.

[CharlieTango]

art,

you and i both have errors, sorry on my part. you have used too little weight to represent full fuel, 6.0lb/gal for mogas 6.2lb for avgas x 34.23 gallons.

i used a spreadsheet that doesn't take into account the cg envelope shifting aft beyond 1,000lbs gross.

...I now realize that to you CT bashing is saying anything about the CT that you don’t like. It doesn’t matter to you if it is are true.

your statement was false.

...If you want to fly with full fuel you must carry ballast in the luggage compartment.

this is what i mean by bashing, this isn't true. you absolutely can fly with full fuel and without ballast.

After looking at the pictures of the CT flyins at McMinnville and Page, I would be real surprised if the pilots and passengers weighted in at 252 pounds or less? Most of them anyway.

personal attacks are a poor way to advance your position.

[Super Cub]

Sorry, no personal attacks intended, but 126 pounds average for each

pilot and each passenger is unrealistic. And the pictures prove it.

[artp]

...If you want to fly with full fuel you must carry ballast in the luggage compartment.

this is what i mean by bashing, this isn't true. you absolutely can fly with full fuel and without ballast.

You have yet to show me a W&B calculation without weight in the baggage compartment that is in the W&B envelope. Saying it can be done does not make it true. It goes back to what I was saying earlier about taking the POH and the FAR's seriously. You say you do, but show me the weight and balance calculation you used for your solo flights with full fuel and no baggage. Surely you would not fly without making the calculation.

[CharlieTango]

oh art, some day you and i need to have a cup of coffee or a scenic flight.

look at your above post, to see how you argue.

#1 you quote me and you discussing your absolute requirement for ballast and then argue that i haven't shown a W&B that supports that i fly solo with full fuel and finish with your typical implication that i violate FARs.

#1 you never asked for a W&B, there is no requirement to show you one and in the end you imply i am deficient by not showing it to you. not logical.

#2 you are assuming ( and so was i ) that we are flying under the same constraints.

i drove to the airport and got my POH to make sense of things. my cg range is 13.110 - 18.740in. behind the leading edge of the wing.

the minimum limit of 13.110 does not increase above and below 1,000lbs but remains at 13.110 for all flying weights (there is another cg envelope for empty weights)

on page 13 of my POH are typical loading configurations for CTSW. 2 of the 3 are for (most forward cg ...) and both call for full fuel.

the 3rd of the 3; Full fuel tank and light passenger (most forward CG) calls for 120lb pilot solo / full fuel - 205 lbs / zero luggage.

i don't think this would be within your cg envelope but would be within mine. my guess is that over time flight design changed the envelope on the most forward cg end to minimize sensitivity in pitch. i know a few owners that advocate some ballast for an easier flare.

once again please stop implying that i violate the rules, if you truly believe that enforcement is called for my local FSDO is in reno, call them and give them what you got, otherwise stop pressing that button please.

[artp]

i don't think this would be within your cg envelope but would be within mine. my guess is that over time flight design changed the envelope on the most forward cg end to minimize sensitivity in pitch.

So the bottom line is anyone contemplating buying a new CTSW will have to use ballast if they fly full fuel and don't have at least 28 pounds in the baggage compartment. So how am I bashing the CT by telling others who might believe your claims that ballast is not required? You seem to be resorting to the same logic you use on the safety issue, if you don't have a problem then no one else will.

Finally the "examples" of the W&B shown in the older POH's are just that, examples. I still have a downloaded POH for the 2006 CTSW and all of the examples in that manual show the CG limit moving aft as the weight increases above 1000 pounds. You must have an older version of the plane. The new POH on the FD site no longer mentions W&B. In fact with my plane the actual W&B is not part of the POH. It was buried in a supplemental binder filled with manuals for the other equipment that came on the plane. It would seem that FD is trying to downplay the W&B information.

[Cub flyer]

OK. It came to me while reading the above posts.

Since I don't have an airframe here to measure and this is a little backwards try to follow along.


Arts CT empty weight is 771.4 lbs. EW CG is 12.51 Moment is 9650.21 in lbs

I weigh 170 lbs X 20.5" = 3485.0 In / Lb

Full fuel is 212 lb X 11.8" = 2501.6 In/ Lb

Total weight for this flight is 1153.4 lb CG is 13.55 inches Total moment is
15636.81" Check to see if this is in Arts envelope. It would be ok on the CT we had because it had the same limits as Charlie Tango's

This is where we frequently operated. But our airplane had a different empty weigh and CG.



Now lets go to the forward limit for examples sake.

1153.4 lbs X 13.11" = 15121 in lbs

I don't have an airframe but I am estimating the horizontal stab center of pressure (25% of chord) to be 15 feet from the CG or 180"

15121/ 180 = 84 lbs downforce on the tail in level flight.

Take this and add the 18" stretch of the new LS.

15121/198 = 76 lbs downforce in level flight.

The downforce loads increase with pitch changes but the general change the stretch does is what is important.

Now lets take the 76 lbs X 180" to get a total desired moment of 13680 in lb.

13680/1153.4lbs = 11.8" CG location. This CG location is not important. What is important is the total change of 1.31"

If you notice the 1.31 " happens to be about the amount of change FD put into the forward CG envelope on Arts airplane.

13.11+ 1.31= 14.42"

There are three ways to increase tail power. Change area, change airfoil, change arm length.

FD modified the antiservo/trim tab to nearly full span. This was an attempt to fix this. Now they are making the tail longer.

Ask if the LS goes back to the original 31.11 forward CG limit.

I bet it does.

The stretch allows the stabilator to have enough power during operations at the forward CG limit. Changing the forward CG limit was just a Band-Aid until the longer fuselage was marketed.

Since Arts manual is changed and it is up to the owner of a LSA to keep their manual revised doesn't everyone have to use the new limits unless there is a serial number range listed?

Thinking back we only had trouble when solo with full fuel. I had my pitch down trouble then. Boyd had his trouble then. We were having floating problems because the idle was too high and since full flaps were tough we flew around the pattern full fuel to get it to sink quicker and kill some float. Set up exactly into this scenario.

Flown within the new envelope numbers you should not have any problems.

Measure an actual airplane and substitute numbers to see how it works out. The later airplanes should be more tail heavy than ours with airframe changes.


Happy Holidays. Glad for some diversion to get the brain working.

[Cub flyer]

http://www.zenithair.com/kit-data/ht-90-5.html


I understand what I posted above is greatly simplified and that the downforce required is actually higher than shown because the airfoil has a pitching moment. But you get the idea.

Read the link above for a good explanation also.

[artp]

Total weight for this flight is 1153.4 lb CG is 13.55 inches Total moment is
15636.81" Check to see if this is in Arts envelope. It would be ok on the CT we had because it had the same limits as Charlie Tango's
1153.4 lbs X 13.11" = 15121 in lbs

According to my W&B sheet the forward limit at 1153.4 is 14.18 so it would be out of CG limits.



To calculate my envelope forward limit for any giving weight between 990 and 1320 (CGfl = (W - 990) * .0055 + 13.28)

[CharlieTango]

So the bottom line is anyone contemplating buying a new CTSW will have to use ballast if they fly full fuel and don't have at least 28 pounds in the baggage compartment.

not really art, there are a number of new ctsw's for sale that are not as new as yours and not necessarily as heavy as yours, not necessarily made with the same purchase/weight carbon fiber as yours and have less equipment installed. your 28lb number might be correct for your aircraft but each ctsw weighs and balances differently.

So how am I bashing the CT by telling others who might believe your claims that ballast is not required? You seem to be resorting to the same logic you use on the safety issue, if you don't have a problem then no one else will.

i already pointed out that you and i were operating under the assumption that our POH cg envelope applied to each other's aircraft but they don't. based on this assumption you assumed i ignore my POH, viloate FARs and fly outside my cg envelope. likewise i assumed you were wrong because your statement was wrong for my ctsw and others that i have flown.

i never made the comment that if i have no problem ( safety issue ) than no one else will, you are putting words in my mouth again.

Finally the "examples" of the W&B shown in the older POH's are just that, examples. ...

they are examples from my POH and they are examples that are within the cg envelope defined by my POH. they support my contention that i can fly full fuel without luggage.