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New E-Prop install

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My CT is a bit heavy 380kg or about 836 pounds.We have the same LSA limit at 600kg. It is a bit over equiped with dynon sv screens big garmin and all the options like leather etc.

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4 hours ago, AGLyme said:

ct9000, can you tell us how much your plane weighs?  And, what the gross weight limitation is over in  your parts?
Many thanks... sounds like a VERY cool CT... 

 

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23 hours ago, ct9000 said:

My CT is a bit heavy 380kg or about 836 pounds.We have the same LSA limit at 600kg. It is a bit over equiped with dynon sv screens big garmin and all the options like leather etc.

Mine is 835 as well... but I have a 912iS which i think is about 40 lbs heavier than the carb 912.  And my plane is loaded with Dynons... which I love.  I haven't had to "not fly"  or make special provisions due to weight limitations yet.  And it's nice burning less gas.  Vast majority of my flying is by myself and with other planes.

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The legal limit is 1320 lbs, but your plane doesn't care up to 1500 lbs. The two CT's that flew around the world was 1645 lbs. and that was across oceans and continents with lots of terrain.

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Roger says your airplane doesn't care about the weight up to 1500lbs.  Float equipped FDCT are permitted up to 1430 lbs, if I remember right.  Someone can correct me it that's wrong.  Well, that's only 70 pounds difference.

The wings have a lift vector that points up and the fuselage weight vector goes down.  If the vectors are not in balance, if the  fuselage is too heavy, at some point the spar carry-through will fail.  One wants to be a little careful about the idea that "if you can stuff it inside it will carry it".  Reaction to gusts is one area of concern.

The airplanes that flew around the world, if I remember right, carried 80 gallons of fuel in the wings.  That fuel was over the lift vector so it did not add stress in the form of a heavier fuselage that would increase the weight vector and stress on the carry-through spar.

Many airplanes have a zero fuel weight which is designed to address the design requirement to prevent the fuselage vector from exceeding what the carry-through spar can withstand.

For a more detailed explanation search on zero fuel weight.

All this ignores CG and weight & balance.

Of course, the response will be "well, I know ole Joe flew at over 1550 pounds" and "Mary scaled her CT at 1600 pounds" but anecdotes don't say much about the physics.  One of those physics issues would be the gust factor of an aircraft that is that heavy.  I will say your maneuvering speed would be nicely high.  :)

I'm not telling anyone to do anything, just saying some operations bear a little thought.

 

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55 minutes ago, Jim Meade said:

Roger says your airplane doesn't care about the weight up to 1500lbs.

 

Maybe, but your license might care if something went wrong and you were over 1,320 lbs. Even if that “something” had zero to do with your over gross condition.

If you value your license, don’t intentionally violate your plane’s Operating Limitations. 

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41 minutes ago, Jim Meade said:

Roger says your airplane doesn't care about the weight up to 1500lbs.  Float equipped FDCT are permitted up to 1430 lbs, if I remember right.  Someone can correct me it that's wrong.  Well, that's only 70 pounds difference.

The wings have a lift vector that points up and the fuselage weight vector goes down.  If the vectors are not in balance, if the  fuselage is too heavy, at some point the spar carry-through will fail.  One wants to be a little careful about the idea that "if you can stuff it inside it will carry it".  Reaction to gusts is one area of concern.

The airplanes that flew around the world, if I remember right, carried 80 gallons of fuel in the wings.  That fuel was over the lift vector so it did not add stress in the form of a heavier fuselage that would increase the weight vector and stress on the carry-through spar.

Many airplanes have a zero fuel weight which is designed to address the design requirement to prevent the fuselage vector from exceeding what the carry-through spar can withstand.

For a more detailed explanation search on zero fuel weight.

All this ignores CG and weight & balance.

Of course, the response will be "well, I know ole Joe flew at over 1550 pounds" and "Mary scaled her CT at 1600 pounds" but anecdotes don't say much about the physics.  One of those physics issues would be the gust factor of an aircraft that is that heavy.  I will say your maneuvering speed would be nicely high.  :)

I'm not telling anyone to do anything, just saying some operations bear a little thought.

 

The max weight of non lifting parts is in the w&b sheets for the aircraft and must not be exceeded. The wings are obviously lifting parts and so do not count also the fuel in the wings not counted as well. So what this means in approximate figures is a/c empty wt. say 380kg less the wings and fuel. or to put it another way the fuselage + rudder + stabilizer is 290kg. The max weight of non lifting parts is 519kg giving a load of 229kg for pax baggage etc. The wings are about 37kg each but the wings and fuel do not count as I said. These numbers are for my a/c and each one will be different. The design and testing for mine was done for 750kg

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I don’t doubt the CT is capable of far more g weight.  Sadly in this day and age everyone wants to blame the pilot, including the owner pilot’s insurance man. Flying overweight is just one of those gotchas that defies the risk /reward game.  I’m a woos about flying over weight.

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1 hour ago, AGLyme said:

I don’t doubt the CT is capable of far more g weight.  Sadly in this day and age everyone wants to blame the pilot, including the owner pilot’s insurance man. Flying overweight is just one of those gotchas that defies the risk /reward game.  I’m a woos about flying over weight.

Please do not take what I said as suggesting that we fly over max weight. The point is that it matters more  where the weight is than the total. For example the max speed in rough air depends on the weight of non lifting components. It is very hard on the structure to fly fast in rough air with light fuel load, even though it is legal weight it is dangerous. On the other hand having a full fuel load may put you over gross but is much safer in rough air and easier on the structure. The max 600kg limit is more about legal issues than structure safety. It is important to understand the difference especially if you get caught in some really nasty stuff

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I didn’t take your comment the wrong way sorry about that.  I was just pontificating in case someone took the scientific argument the wrong way.  

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I'm guessing that somewhere in the +4/-2 G limit is where this all meets.  I had thoughts of putting together a spread sheet that calculates the G stress on the airplane at variable weights but I didn't really see a good reason for it.  

I have  a spread sheet that calculates my Vs based on actual weight at bank angles up to 60 degrees.  Also does Vs x 1.3 and best glide, all based on weight.  That way at a glance I can tell what these speeds are based on a given weight.

If If I remember right the 1500lb number is what the aircraft is certified for in other countries(I could be totally wrong so don't hold this against me)

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Remember that as for most airplanes, the wing loading is rarely the problem.  The tail is likely to fail *way* before the wing does.  And it's going to happen when g-loaded, not just flying straight and level in relatively calm air.

I have no doubt the CT series is perfectly safe up to 1500lb.  I also know the FAA doesn't like that. 

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The thing is that this is a curve not a hard limit ... meaning that as you get closer to the 1500  lbs “limit” all other limits  get progressively worse ( higher stall speed, lower G limits etc ) so I would not call it “perfectly safe”...

I remember during my checkride my DPE ( a retired airline pilot) asked me about the very same thing - can you fly over gross and then when I predictably said no way, he completely surprised me with something like “ of course you can, you just have to be cognizant of the fact that the plane will differently and make sure to provide yourself with a lot more safety margin”

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1 hour ago, Warmi said:

The thing is that this is a curve not a hard limit ... meaning that as you get closer to the 1500  lbs “limit” all other limits  get progressively worse ( higher stall speed, lower G limits etc ) so I would not call it “perfectly safe”...

I remember during my checkride my DPE ( a retired airline pilot) asked me about the very same thing - can you fly over gross and then when I predictably said no way, he completely surprised me with something like “ of course you can, you just have to be cognizant of the fact that the plane will differently and make sure to provide yourself with a lot more safety margin”

There is a "hard limit" where one additional pound of load causes a failure.  Somewhere.  The problem is we don't ever know exactly where that is.  You might be 200lb over gross and pull 2g ten times and be fine.  Then you do it again and this time hit 2.1g and...oops...

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2 hours ago, FlyingMonkey said:

There is a "hard limit" where one additional pound of load causes a failure.

I like your thought experiment that followed.

There’s also a “hard limit” where your license becomes at risk should a mishap occur. Right at 1,320 lbs.

And what that DPE mentioned above said to an impressionable applicant is almost criminal. It sends the message that Limitations are optional and only be adhered to at the discretion of the pilot. I don’t know if any pilots actually died as a result of his attitude, but I wouldn’t be surprised.

And, yes, this is a sore point with me. 

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3 hours ago, FlyingMonkey said:

There is a "hard limit" where one additional pound of load causes a failure.  Somewhere.  The problem is we don't ever know exactly where that is.  You might be 200lb over gross and pull 2g ten times and be fine.  Then you do it again and this time hit 2.1g and...oops...

Yep. As far as I am concerned , this curve I was talking about starts way below Vno and only gets worse with higher weight/airspeed so the net effect is that I tend adjust my airspeed and limit my maneuvering envelope based on how heavy I am, how bumpy it is  ... in other words , forget going over 1320 lbs, depending on conditions you can get a pretty nasty surprise well below that limit ...

I still remember one time flying with my wife close to gross and in somewhat bumpy weather and nearly freaking out when she accidentally but rather forcefully bumped the stick ... 

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Just to clarify a point. The lighter the load the slower the turb speed. If you really want to stress your structure fly with minimum fuel and fill up the cockpit to legal max weight then fly a bit faster, you could die but be legal.

 

 

Ok I am dramatizing a little bit because the speeds are for +4 -2g and most of us slow down when it is bumpy but the fact remains you can enter rough air faster with full fuel than with light fuel load.

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That is true Va decreases as weight decreases since plane stall speed gets lowered as weight increases - but I was always confused about Vno which I don’t quite understand.

Now , from the point of view of physics , if you suddenly change control surfaces and induce acceleration on wings ( since that’s where control surfaces are located) , for a split second the body of the plane will keep going in the direction it was going which will be different than that of the wings and the heavier the body , the heavier the load will be on the parts where wings are connected to the body ... in other words, the heavier the plane in relation to wings the more likely you will be able to break your wings off with sudden control inputs ... this has nothing to do with stall speeds etc ..... perhaps I am missing something here but it seems to make sense to me.

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Like I said, a sore point with me.

First, planes are built with a safety margin built in. It allows for slight miscalculations, aging of the airframe and components, that sort of thing. But every pound above max gross nibbles into that margin. Do you feel lucky?

Also, an overweight condition can just be one link in an accident chain. I know I've mentioned this before, but I'm sure there are new members here who might not be aware. 

I owned  beautiful 1966 Citabria with a partner:

10467045524_dfd0b9f9e2_z.jpg

We used it for tailwheel and basic aerobatic instruction and rental. It was destroyed and two people were killed in a tragic, but foreseeable accident.

Accident basics here (I can't find the more extensive NTSB report right now): https://aviation-safety.net/wikibase/41309

NTSB report can be found searching the N# here: http://www.aviationdb.com/Aviation/AccidentQuery.shtm

Links in the chain: Overweight aircraft. Low altitude aerobatics*. No parachutes carried. Hardware issue that I remain highly suspicious of.**

Perhaps no single factor listed above by itself would have cause the fatal accident. Added together the outcome was probably unavoidable.

11803733445_3a2a47e40b_z.jpg

Sad.

 

*The renter pilot was not checked out for aerobatics. Parachutes were available, but this was not to be an aerobatic flight.

**The apparently missing wing attach hardware seemed highly suspicious. We were just out of an annual, with wing root fairings removed and wing attachment hardware checked. There was reason to remove it. The case was referred to the Broward County Homicide Division, but the case was never solved. I had flown the airplane once since the annual. I was in the gym business, which in that era had very shady elements - see the movie "Pain and Gain" for some idea. To this day I suspect I may have been the target of someone and the plane had been tampered with. But I'll never know.

 

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