How to find the real gross weight a plane can carry?

Talk about airplanes! At last count, there are 39 (and growing) FAA certificated S-LSA (special light sport aircraft). These are factory-built ready to fly airplanes. If you can't afford a factory-built LSA, consider buying an E-LSA kit (experimental LSA - up to 99% complete).

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WDD
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How to find the real gross weight a plane can carry?

Postby WDD » Sun Feb 18, 2018 3:35 pm

An LSA needs to be no more than 1320 lbs to be legal for a Sport Pilot to fly.

Hence, Vans RV 12, Sling 2, etc are rated at 1320.

But is it possible to find out what it can really safely carry? That is, how much margin do you have?

A Sling 2 looks nice because while we would load it only to 1320 lbs, it looks like if you registered it as a non LSA it can carry 240 lbs more. A nice safety margin. Same probably for the Jabiru. Have no idea what the RV 12 could really carry.

Thoughts?

TimTaylor
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Re: How to find the real gross weight a plane can carry?

Postby TimTaylor » Sun Feb 18, 2018 4:08 pm

An LSA is limited to 1320 regardless of who is flying it. It doesn't matter how much weight it could carry.

If you want to fly with more than 1320 max gross, get a medical and private license and fly whatever you want.
Commercial Pilot Airplane Single & Multiengine Land; Instrument Airplane; Sport Endorsement Airplane Single Engine Sea; Flight Instructor Airplane Single And Multiengine; Ground Instructor Advanced Instrument

TimTaylor
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Re: How to find the real gross weight a plane can carry?

Postby TimTaylor » Sun Feb 18, 2018 5:14 pm

TimTaylor wrote:An LSA is limited to 1320 regardless of who is flying it. It doesn't matter how much weight it could carry.

If you want to fly with more than 1320 max gross, get a medical and private license and fly whatever you want.


United States
The Light Sport Aircraft Rule: The FAA defines a light sport aircraft as an aircraft, other than a helicopter or Powered-lift that, since its original certification, has continued to meet the following:[6]

Max. Gross Takeoff Weight: 1,320 lbs (600 kg) or 1,430 lbs for seaplanes (650 kg)
Max. Stall Speed: 51 mph / 45 knots CAS
Max. Speed in Level Flight (at sea level In the US Standard Atmosphere):138 mph / 120 knots CAS
Seats: Two (max.)
Engines / Motors: One (max. if powered.)
Propeller: Fixed-pitch or ground adjustable
Cabin: Unpressurized
Fixed-pitch, semi-rigid, teetering, two-blade rotor system, if a gyroplane.
Landing Gear: Fixed (except for seaplanes and gliders)
Commercial Pilot Airplane Single & Multiengine Land; Instrument Airplane; Sport Endorsement Airplane Single Engine Sea; Flight Instructor Airplane Single And Multiengine; Ground Instructor Advanced Instrument

3Dreaming
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Re: How to find the real gross weight a plane can carry?

Postby 3Dreaming » Sun Feb 18, 2018 5:47 pm

TimTaylor wrote:An LSA is limited to 1320 regardless of who is flying it. It doesn't matter how much weight it could carry.

If you want to fly with more than 1320 max gross, get a medical and private license and fly whatever you want.


Who is suggesting that the limit is anything other than 1320? The OP said in his post that the limit is 1320. He didn't say he wanted to fly at more than 1320, in fact he even emphasized again that a sport pilot could only fly it at 1320 pounds.

I think he just wants to know if there is an increased safety factor based on the same aircraft under different certification being able to operate at a higher gross weight. The answer to that question would be, yes.

TimTaylor
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Re: How to find the real gross weight a plane can carry?

Postby TimTaylor » Sun Feb 18, 2018 5:50 pm

Stop following me around the internet. The only reason people ask that question is because they intend to overload an LSA. Otherwise it's moot. You cannot register an LSA as something else to get around the LSA weight limit of 1320. If the manufacturer came out with a higher gross weight certificated model, then it wouldn't be an LSA and would require a Private.
Commercial Pilot Airplane Single & Multiengine Land; Instrument Airplane; Sport Endorsement Airplane Single Engine Sea; Flight Instructor Airplane Single And Multiengine; Ground Instructor Advanced Instrument

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WDD
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Re: How to find the real gross weight a plane can carry?

Postby WDD » Sun Feb 18, 2018 7:24 pm

So.......

Back to my original question.

How much safety margin is there on LSA planes beyond the 1320 lbs? Do LSA's regularly have performance to spare well above 1320 lbs?

And no this thread isn't on how to overload an LSA beyond 1320 lbs.

TimTaylor
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Re: How to find the real gross weight a plane can carry?

Postby TimTaylor » Sun Feb 18, 2018 7:29 pm

WDD wrote:So.......

Back to my original question.

How much safety margin is there on LSA planes beyond the 1320 lbs? Do LSA's regularly have performance to spare well above 1320 lbs?

And no this thread isn't on how to overload an LSA beyond 1320 lbs.

Yes, many do, until you crash. At that point, the additional weight will result in a
much worse outcome. If you don't plan to overload your LSA, it's a moot point.

The question I would ask is what is the useful load, climb performance, take-off distance, landing distance, etc. at max gross weight.

Why would it matter if you flew an LSA that could technically haul 1560 pounds?
Commercial Pilot Airplane Single & Multiengine Land; Instrument Airplane; Sport Endorsement Airplane Single Engine Sea; Flight Instructor Airplane Single And Multiengine; Ground Instructor Advanced Instrument

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FastEddieB
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Re: How to find the real gross weight a plane can carry?

Postby FastEddieB » Sun Feb 18, 2018 7:52 pm

I kinda side with Tim here.

If someone told me my Sky Arrow was actually safe up to 1,450 lbs, how would it affect my operations?

It wouldn’t. Not one little bit.

So what difference would it make? And why even waste time on pointless hypotheticals?
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

TimTaylor
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Re: How to find the real gross weight a plane can carry?

Postby TimTaylor » Sun Feb 18, 2018 8:12 pm

I don't like the question because, regardless of the intent, it implies that it might be OK to violate the max gross weight if you want to. I think it conveys a bad message. We should be all about abiding by all the regulations whether or not we like them.
Commercial Pilot Airplane Single & Multiengine Land; Instrument Airplane; Sport Endorsement Airplane Single Engine Sea; Flight Instructor Airplane Single And Multiengine; Ground Instructor Advanced Instrument

Warmi
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Re: How to find the real gross weight a plane can carry?

Postby Warmi » Sun Feb 18, 2018 8:53 pm

WDD wrote:An LSA needs to be no more than 1320 lbs to be legal for a Sport Pilot to fly.

Hence, Vans RV 12, Sling 2, etc are rated at 1320.

But is it possible to find out what it can really safely carry? That is, how much margin do you have?

A Sling 2 looks nice because while we would load it only to 1320 lbs, it looks like if you registered it as a non LSA it can carry 240 lbs more. A nice safety margin. Same probably for the Jabiru. Have no idea what the RV 12 could really carry.

Thoughts?


I guess the only way to find out is to download POHs manuals for planes certified with different gross weights in different jurisdictions.That will give you everything, including various V speeds, as applicable.

For pure LSAs , like Rv12 , going over gross you would be essentially testing various engineering margins of safety built into to the design - not exactly something I would want to play with :D
Flying Sting S4 ( N184WA ) out of Illinois

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Re: How to find the real gross weight a plane can carry?

Postby Sling 2 Pilot » Mon Feb 19, 2018 9:58 am

FastEddieB wrote:I kinda side with Tim here.

If someone told me my Sky Arrow was actually safe up to 1,450 lbs, how would it affect my operations?

It wouldn’t. Not one little bit.

So what difference would it make? And why even waste time on pointless hypotheticals?


Eddie,

Your 2007 Sky Arrow is probably good to go up to 1600 or so. When 3I entered the LSA market they used 650 TCNS airframes, which were certified at the increased weight. I found this out in conversations with Hansen over the years. In fact Magnahi’s first Sky Arrows were said to have a few left over fuselages from 3I.

That said, I am in agreement with you and Tim, if the aircraft is certified as an LSA that’s what is has to be flown as.

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MrMorden
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Re: How to find the real gross weight a plane can carry?

Postby MrMorden » Mon Feb 19, 2018 10:57 am

You'd have to define "safe".

Two guys flew CTSWs around the world at 1675lb. Is that safe? Maybe for them as highly experienced ATPs, but not for me with my under 1000 hour Sport Pilot ticket.

Was it structurally safe? Who knows, the CTSW was not designed for weights that high. The wing on the airplane is very strong and I'm sure is okay at that weight, but what about the tail in hard maneuvering or turbulence? What about the landing gear? What is the Va at those weights? All unknowns.

So again...what is "safe"?
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

3Dreaming
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Re: How to find the real gross weight a plane can carry?

Postby 3Dreaming » Mon Feb 19, 2018 11:03 am

TimTaylor wrote:Stop following me around the internet. The only reason people ask that question is because they intend to overload an LSA. Otherwise it's moot. You cannot register an LSA as something else to get around the LSA weight limit of 1320. If the manufacturer came out with a higher gross weight certificated model, then it wouldn't be an LSA and would require a Private.


Tim, I am not following you around the internet. I am an active member of this forum, and have been since before you joined. If you would like an example of someone following someone around the internet I would be happy to provide one.

The OP ask about safety factor, not if the airplane could haul more weight. He made it clear that he would be operating at the 1320 pound gross weight. He didn't need a brash lecture from you on the rules, especially when it is clear he already knows what they are.

3Dreaming
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Re: How to find the real gross weight a plane can carry?

Postby 3Dreaming » Mon Feb 19, 2018 11:26 am

WDD wrote:So.......

Back to my original question.

How much safety margin is there on LSA planes beyond the 1320 lbs? Do LSA's regularly have performance to spare well above 1320 lbs?

And no this thread isn't on how to overload an LSA beyond 1320 lbs.


You should not look at safety margin in terms of operating beyond 1320, since in fact that is the limit. There are factors that go far beyond the weight an airplane can take off and climb with. You also need to be able to withstand normal flight loads. On a airplane like a LSA an increase of 200 pounds will reduce your safety factor by about 15%. That is certainly something to think about when considering loading beyond the 1320 pound limit.

Warmi
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Re: How to find the real gross weight a plane can carry?

Postby Warmi » Mon Feb 19, 2018 11:42 am

MrMorden wrote:You'd have to define "safe".

Two guys flew CTSWs around the world at 1675lb. Is that safe? Maybe for them as highly experienced ATPs, but not for me with my under 1000 hour Sport Pilot ticket.

Was it structurally safe? Who knows, the CTSW was not designed for weights that high. The wing on the airplane is very strong and I'm sure is okay at that weight, but what about the tail in hard maneuvering or turbulence? What about the landing gear? What is the Va at those weights? All unknowns.

So again...what is "safe"?


Yeah, it is hard to say - pretty much all LSAs operate with the same basic safety margins (gross, stall speeds ) but at the same time differ in their various V speeds. For instance Sting has 165 Vne , which is pretty high in the LSA world ( for instance Sling 2 has 135 knots , quite a bit of difference )
My understanding is that Vne limits are more about flutter risks rather than structural issues but I am still curious why so much difference - is it related to actual design or perhaps to liability issues ( risks vs benefits ) ?
Flying Sting S4 ( N184WA ) out of Illinois


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