Gross weight question - long EZ

[cracker928]

Reading accident reports, I came across this:  http://aviation-safety.net/wikibase/wiki.php?id=35388

Does the exceeding gross weight sound right?  I know that not all detail are disclosed but doing the quick math using the wikipedia empty and gross weights seems to be barely in spec...

Being new to the EZ scen, I must be missing something.

[LongEZDaveA]

The NTSB report shows that the calculated gross weight was 1520 pounds.  Although this is about 200 pounds over the normal gross weight for a Long EZ, I don't think it had much to do with the crash.  I think the reported 90 degree banks and flying at low altitude tell the story.

[Bruce Hughes]

Hi (whatever your name is)

My Longeze (which has not flown) is heavier than that when full of people and gas.
I am still trying to take off a few pounds.
   
I will NOT be afraid to fly it but I will be D*MN sure that the CG is right.   That is
critical (and lighter would be nice)

Dick Rutan flew a Longeze which was much heavier than mine (with a huge gas tank
in the back seat)(to fly for a record).   I will NEVER fly any steep turns, especially at
such an altitude.

You probably do not know that we lost one pilot (I cannot spell his name but it was
something like Fessington) flying steep turns at an air show.

Those guys were hotdogging.  We need such people to get out of flying into car or
boat racing.

Bruce Hughes   

[cracker928]

OK, thanks.  I had previously missed the complete narrative form the NTSB.

But on the subject of gross weight, I have read that people often exceed the rutan-specified gross weight limits for their ez's and feel that it is perfectly safe.  Why is this, and if this is a common practice, then what is the practical limit?

I fully understand that exceeding the gross weight is a bad practice, but I also also understand that many people can placard the plane to a higher limit.

Thanks in advance.

-Neil

[Bruce Hughes]

I have been told to not say anything about canards as I am not an engineer and I do
not know what I am talking about.  Having said that, there are some obvious facts.

1. If built CORRECTLY, the canards are extremely strong.  Compare that to aluminum airplanes,
    either homebuilt or certificated.   The rear seat, in particular, is pretty safe.  I have a
    few parts from a Longeze that landed in a forest.  The pilot was killed but not the
    passenger.  Try that with an RV.
2. If your airplane turns out heavy, as mine is, you may have trouble getting the CG right.
    I have 25 pounds of tools in the nose and a battery that is bigger than necessary.
    Be careful to build correctly (I took over a project so maybe it is not all my fault).
    If you are a really big guy, the CG is easier to get right, even is the canard is a little
    heavy.
3.. If you have a forced landing, the energy to be stopped (by trees, rocks, whatever)
    is elated to the SQUARE of the landing speed.   If your canard was built too heavy,
    the landing speed will be higher.
4. If you are landing on a decent runway, just be sure you have good brakes.  Recently
    I discarded what I had and put Grove brakes on.  That is an important reason I feel
    fairly safe to fly it (if it ever flies)(I don't have FAA approval yet)
5. If you use a smaller engine and light propeller and are pretty heavy yourself, you might
    even have the CG too far farward.   Unlikely but you have to get the CG CORRECT.
6. You are the builder; you can legally set the maximum weight as whatever you want.
    You just need to pay attention to #1,2,3, and 4.
7. We don't have stall/spin accidents IF you get the CG right.
8. Look in the CSA directory; most builders give their empty weight.
9. Some builders have a light airplane but they are so heavy themselves that they will
    die of a heart attack or diabetes.   I can name names on that one.  I weight 160
    which is a little heavy for 5'7"
10. Did I say to be sure to get the CG right?

Bruce Nughes   

[cracker928]

Thanks Bruce. 

My situation is that I am shopping for an ez that somebody else built.  I am not sure how that affects item #6 on your list.  I am wondering if it is possible to change the GW that the original builder specified, and if to what limit is a practical safe GW as proven by many other EZ flyers.

Thanks,

Neil

[Joe Person]

I'd NEVER operate beyond the per-plans gross weight for an airplane that was built by someone else.  Furthermore, I would also not operate ANY experimental homebuilt above the max gross weight it is PLACARDED for (and I mean, "PLACARDED", as in, "what the original builder specified in HIS paperwork that was reviewed and accepted by the FAA as part of the Experimental Airworthiness process").  If you are looking to buy a Long-EZ, PLEASE get a qualified builder/operator (who knows how to build properly, BTW...) to have a look-over the prospective airplane.  Too many people build crap (IMO, one crap airplane is too many...), and rationalize things away, including the unfounded belief that, "well, it has been flown for xxx hours, so it must be OK...".  We've seen examples of seemingly nicely-built (read, "nicely finished") airplanes that had hidden flaws - several of these flaws have been fatal.

[Bill James]

A friend bought a nice looking, well equipped EZ with a big motor. One day soonafter he came in the hangar kinda pale. He said that with the weight of him and his wife there was room for only 2 gallons of fuel. He doesn't have it any more. He egged me into a race twice, once after installing new wheel pants, each time extremely frustrated that he couldn't keep up. Weight counts.
I once heard of an 0-320 VEz with a min speed of about 100 mph...

[Bruce Hughes]

I missed the fact that you are searching for an airplane.   I thought you were planning to
build.  There is a big difference.  Heavy canards probably have too much epoxy per oz
of glass, which makes them weaker.  Being heavy AND weak is a double NO, NO.

I would NEVER consider BUYING a canard that is heavy; I am just stuck with one that I
MADE too heavy by using too much West System and putting a big engine and 3 blade
prop on.   I still can put a reasonable amount of gas and myself in it and fly at 1400 lb
so 1520 for the plane that crashed was too heavy.  The weight is NOT the reason that
they crashed; they did stupid flying at a high altitude that got one of them killed.

If you find a possible purchase, have Bill Oertel look at it, if it is in CA.   He is at Cheno airport.
If it is farther north, see if Dale Martin can look at it.   If it is in CO, Burrall Sanders can inspect
it.   Any of these 3 will charge a fee and it will be the best use of money you ever made.
They will not let you buy some cr*ppy, overweight airplane (like mine).   If it is somewhere
else, don't do anything until you find an expert (by asking us).   I only know of 5 people that
I would trust to look at it.

I still consider the Longeze safer than those aluminum things.   "show-off" flying is unsafe in
any airplane.

Bruce Hughes   

[EZPILOT742X]

I'm curious about what weights we are talking about. I don't think it's anything like asking a woman how heavy she is! :-) I fly an IO-320 Berk-EZ and am about 1040 lbs empty. Sure, that's very heavy for a 1980's vintage Long with an O-235 on it, but these airplanes have evolved quite a bit since then, with necessary structural appointments to handle larger engines, etc. I'm a 240 lb pilot so with 30 gallons of fuel and no baggage or passengers that has me flying around 1450 lbs. all the time. At that weight, my plane flies like a bat out of hell and handles great. I'm sure it would have a touch of extra zip an crisp if I were able to build it 150 pounds lighter, but I was a first timer, incorporating Berkut mods (larger canopy, long nose, steel roll bar, el. nosegear, etc.) and ended up with some heavy finish areas on my strake skins. I set my gross weight at 1800 lbs. during my airworthiness inspection/paperwork and have operated the airplane at or near that weight quite a few times. At around 1800 I use about 1000 ft. more in the ground roll and climb performance is reduced, but the airplane is still capable and comfortable to fly. I smacked the shit out of it on landing one night and after a thorough look there was no damage at all. I fly it as I would any other airplane that is loaded to gross or above, and keep the same safety precautions in mind.

Chris

[cracker928]

Thank you all for the information;  I have e-mailed Dale Martin. 

As for the "too heavy", what would that be?  I have read that the design specd 710 empty weight might be optimistic, so what empty weights do the other EZ's on this forum have?

-Neil

 

[Bruce Hughes]

BTW  There are many experts in CA; I just know Bill and Dale.  If they are too busy, they
probably can refer you to a good person that can do inspections.   Just be D*MN sure
you get it inspected before you buy; A few years ago we had a VERY BAD example of a
canard owner trying to sell a pile of junk in southern CA.   The seller insisted on $1000
down and would not return it when it became so obvious that nobody would dare to fly
it.  The swindled guy had paid air fare from the east, too.

The only way to see what the minimum speed would be (as far as I know) is to get it to a
reasonable altitude and test it.

If you are planning to buy a Longeze that is already flying, your maximum weight has been set
by the builder.   You cannot, as far as I know, change that.   So you need to see what limit
he set.   

As you did not build it, you have a problem doing an annual inspection.  I think Bill Oertel or
Dale Martin can do that but you better ask one of them.   Ask your CSA state representative
or Joe Person or Dale Martin; any of them knows about 100 times as much as I do.

I am still trying to take a few pounds off of mine.   As I said, I can legally fly at 1400 lb.   When
the test period is finished the CG range opens somewhat.   That will allow me to take some tools
out of the nose so I will be around 1380 or I can carry more gas.    Sure I wish it was lighter
and I think I can get it down to 1360 lb.

Bruce Hughes   

[Bill James]

You mentioned the practical aspect of operating over gross weight. Several things come to mind.
One, maximum landing weight. We have heard that the gross weight value of 1080 lbs was used hundreds of times when designing the VariEze. The allowable gross weight was later said to be 1120 with a bigger engine, but the max landing weight was still 1080.
An example, the first Long EZ was flown 33 hours non stop. Yes it would get in the air even though massively overloaded, but the gear structure was still designed for 1325 lbs (I think that was the initial value). Also, a cable was needed to hold the gear struts from flexing outward on takeoff. They were concerned about being so heavy if they had to land soon after takeoff.
 When evaluating whether our particular aircraft could be operated at over-gross weights we are tempted to see ourselves milking through a feather soft landing. But actual over weight use often results in the gear being rebuilt. True with any type airplane.
Two, minimium speed. Particularly in an unplanned off-airport landing. Several years ago I read about a bush pilot that used an angle of attack AOA needle/plate on the wing strut to check that his approach or climbout AOA was optimum. Not speed, AOA. AOA worked perfectly, every time. Even on Navy carrier approaches  
The practical takeaway was that his low weight approach speed was around 60 and his high weight speed was around 95, both at the same AOA. His cruise speed was not much higher  
A particular wing will always stall at the same AOA. But the stall speed varies greatly, dependent on weight. For our stall-resistant aircraft design, this critical factor is minimum speed. While we may focus on approach speeds, the real issue is minimum speed. In the bush plane example, his cruise speed was not much higher than his high-weight approach speed. For our speedsters, we can also overload the plane such that the higher minimum speed greatly reduces the probability of a successful off-airport landing. Because of carrying too much energy into the mix.
And there’s more. Its not just minimum speed. The approach speed includes the requirement to have enough extra energy to flare and dissipate the rate of descent. Several years ago a fighter guy flew his Long EZ through a pattern simulating a high rate-of-descent accident scenario. He determined for the flare on a normal landing his LongEZ would need an approach speed 22 mph above his minimum speed.
How do you determine minimum speed?  I know mine.
For a builder, per the POH, this is accomplished during the restricted period at altitude, preferably with a parachute.
For a buyer… depends on the buyer I guess.  Again, it is important to know and observe these speeds in any aircraft.
All said, I believe the EZ design provides superb all around flight qualities and capabilities, and an optimum airframe for exercising our passions.

[Bill James]

And for angle of bank, also an element of your initial question, see the Jan 2011 Sport Aviation, page 52, 4th paragraph. Arnold Ebneter's interesting solution to testing his plane to determine fuel burn at gross weight, when he only intended to fly 20 minutes per test flight and his landing weight was hundreds of pounds below gross....

[Bill James]

More thoughts on the practical considerations on operating above gross weight.
Two unidentified pilots were returning from a fly in, descending from altitude for landing. The GIB, guy in back, was flying and pushed the nose over, increasing the airspeed to about 190 mph, enjoying the rush. The front-seater pulled the power back and said he had the airplane. The GIB asked what’s wrong, he was just trying to speed up and take advantage of the descent.

The front-seater said that they needed to slow down. The GIB asked what the problem was, because the Vne, max speed, was 220 mph.
The front seater said he expected that when they got down to around 4000 feet where the base of a scattered cloud layer was, that they would probably hit some turbulence. The GIB scoffed and said so what, it’s a strong airplane, and he was only doing 190, and the Vne was 220.
The front-seater, an engineer, had just bought the plane, and had done his homework. He said that with the probability of turbulence that he would be slowing closer to the maneuvering speed, 140 mph.
Descending through 4000 feet they did experience moderate turbulence.
The GIB asked him to explain his concern. The engineer talked through a quick calculation including their weight, which was near max gross, a speed of, say, 200 mph, and how many Gs they could have experienced. He concluded with the fact that the airplane wasn’t designed for that, and the he expected that the structure would in fact fail in that scenario.
One question might be, if a new owner decides that his max gross weight is, say... 1600 lbs, what is the maneuvering speed? And the Vne?  Again, these are concerns with any airplane.
The point here is the effect of operating your aircraft above design max gross. Curiosity of maneuvering speed and penetration speed would involve personal study, should one be interested…