Long EZ CG Calculations

[Drew]

Hi All,

I have the opportunity to buy a flying Long EZ. But its a few weeks before the owner is back in town.

Being 6'4", 250#, I thought I'd look at  the CG / W&B calc's using the POH from these forums's, as I can see this being a problem.

Now, the POH has the Empty as 730#, but we all know that almost impossible.

Can someone share the Load calculations please, so I have a bit of a guide?

The owner says the EW is 880#, but dont know where the CG is to do a proper calc.

Edited October 31, 2023 by Drew

[Marc Zeitlin]

1 hour ago, Drew said:

 

Being 6'4", 250#, I thought I'd look at  the CG / W&B calc's using the POH from these forums's, as I can see this being a problem.

Probably not, but certainly worth examining for any particular Long-EZ. They're ALL different.

1 hour ago, Drew said:

Now, the POH has the Empty as 730#, but we all know that almost impossible.

There may be one or two LEs on the planet that weigh less than 800 lb., but I'd bet a lot of $$$ you haven't found one.

1 hour ago, Drew said:

Can someone share the Load calculations please, so I have a bit of a guide?

The methodology for W&B on LEs is in the POH - it's just like every other aircraft. There's no magic.

1 hour ago, Drew said:

The owner says the EW is 880#, but dont know where the CG is to do a proper calc.

An empty weight of 880 lb., even for an O-235 LE, wouldn't be that lousy. But without more information, the number is meaningless. Unless you have an empty CG location, as well as verification of all the fuselage stations for the main wing/strake intersection, main gear axles, nose gear axle, canard, and front seat (which is very dependent upon WHO is sitting in it), whether the empty weight is 750, 950, or 1150 lb. doesn't tell you squat.

Get a copy of the latest W&B that was done and then have someone that REALLY knows canard review it to see if it can be trusted - most can't and are out of date at best.

[Drew]

Thank Marc,

Yeah, i have no problem working out the WB etc. And the weight only is next to useless, but was hoping someone had actual number that i could play with. Ideally of an EZ around the same weight.

The POH is in the aircraft, but still a few weeks before I get to meet it. Its only a few miles from my place, but people are a bit touchy about breaking into their hangers

[Marc Zeitlin]

8 hours ago, Drew said:

Yeah, i have no problem working out the WB etc. And the weight only is next to useless, but was hoping someone had actual number that i could play with. Ideally of an EZ around the same weight.

I've seen empty CGs of Long-EZs anywhere from 109" to 112". The book value of the pilot's seat arm is 59". Fuel at 104", and rear seat at 103". CG range is 97" - 103". Assume that the 880 lb. is BS, particularly if it's got an O-320 - I'd go with somewhere between 900 lb and 1100 lb to be conservative, until the plane is actually weighed.

So with those #'s you can play with what happens in various configurations and cases. But you still won't know dick about THIS plane - only what it MIGHT be, if...

[zolotiyeruki]

20 minutes ago, Marc Zeitlin said:

Assume that the 880 lb. is BS, particularly if it's got an O-320 - I'd go with somewhere between 900 lb and 1100 lb to be conservative, until the plane is actually weighed.

I hate to hijack this thread, but I hate even more to start a new thread when this one is already discussing the topic.  If the plans empty weight is supposed to be ~730 lbs, and installing a larger engine adds 150 lbs (gotta have a battery to go with that starter!), where do you typically see the extra 220 lbs (to get to 1100) coming from?

[Marc Zeitlin]

4 hours ago, zolotiyeruki said:

... If the plans empty weight is supposed to be ~730 lbs, and installing a larger engine adds 150 lbs (gotta have a battery to go with that starter!), where do you typically see the extra 220 lbs (to get to 1100) coming from?

No Long-EZ has ever weighed 730 lb., except maybe N79RA with an O-200, if it had one.

98% of LEs have either O-235s or O-320s. An O-320 weighs about 50 lb. more than an O-235.

Additional weight comes from many disparate areas, in no particular order:

• Too much fill (and too wet fill), due either to poor underlying contour or poor understanding of the weight of excess fill
• Adding layups/glass plies (and the epoxy to wet them out) where not needed for "extra strength"
• Poor squeegeeing/stippling technique and overly wet layups
• Systems way over and above the minimal systems installed in the original Long-EZs
• Heavy starters, alternators, additional batteries
• Full stack IFR instrument panels
• Probably other areas I can't recall at the moment

It adds up. The lowest weight O-320 LE I think I ever saw was about 850 lb. - that was probably the lowest weight LE with any engine. The heaviest O-360 LE was/is about 1100 lb.

I took 30 lb. out of an O-235 LE recently by removing a 40 year old Century Autopilot system and the vacuum system and replacing them with a G5/G507 and two GSA28 servos.

[Drew]

1 hour ago, Marc Zeitlin said:

I took 30 lb. out of an O-235 LE recently by removing a 40 year old Century Autopilot system and the vacuum system and replacing them with a G5/G507 and two GSA28 servos.

Its amazing the excess gear and wires you find in some aircraft, and the weight saving with new equipment

[Patrick]

I suggest you start from scratch. Get the owners handbook, it is on line and take the aircraft into a hangar with measuring tape, large steel square, plumb bob and a piece of chalk. If you cannot get a set of aircraft weighing scales, borrow a set of scales from your friendly medical centre, that's what I did. Follow the instructions in the manual, it is quite simple. This is the only way you will be absolutely sure that it is correct and it will only take a few hours. By the way, make sure the aircraft is level when you take the weight measurements, but that's obvious I think.