Useful Load Long EZ

[Arbiter]

Hi Folks,

Working on starting an OPEN EZ in the near future and after searching high and low on this site and the internet I couldn't get a good feel for what can be expected for a useful load on the Long EZ. I saw 550 lbs somewhere, but it seems low to me given the 52 gallon capacity which is ~300LB already... Could people shout out their useful load experiences (There should be a spread given people's different configurations, but should produce an average). I looked all over this site and did not see this posted somewhere so I'd appreciate a shout out! Thanks!

 

-Chris

[Waiter]

I have a 160hp O-320

My empty weight is 950.

Myself and one PAX = 400

Baggage = 50

Full fuel = 300

 

With a gross weight of 1700lbs, I need to be carefull of runway length (4000 would be just about minimum) and crosswinds.

 

Waiter

[Arbiter]

Looks like Waiter has a bird about 300lb heavier than Burt's 1425 lb max gross than what I saw in the pilot's handbook I just found. Is this ability to carry more due to any design modifications other than the engine, you said you have an O-320, what's your fuel burn with that engine and that weight? Thanks for sharing, keep the loads coming! I like how Waiter did it, if anyone else wants to I would suggest putting their loads as follows:

 

Engine

Empty Weight

Pax + Pilot Weight

Baggage Weight

Fuel Weight

Gross Weight

Fuel Burn (75% @ ____ ft)

 

If many people contribute to this thread we'll have a good idea of what the current and flying long EZ's can do, Thanks!

 

-Chris

[Spodman]

Bzzzzzzzzzzzz

[Arbiter]

Just buzzing through Spodman??? On with the useful loads of the Long EZ :-D * Dons Viking Helmet * and Immigrant Song by Led Zepplin begins to play....

 

plz post load information asked for above so we can get a good database of load and engine data. Thank you!

 

-Chris

[TMann]

Keep in mind that Waiter has the Infinity retracts which are capable of a higher gross weight than the standard fixed gear is capable of.

[Arbiter]

Keep in mind that Waiter has the Infinity retracts which are capable of a higher gross weight than the standard fixed gear is capable of.

That's good to know. But does that imply the airframe is weight limited by the gear at the normal 1425 lb? Please post data, and to Tmann's point, if you know of any mods that affect your numbers let us know, keep the good points and loads coming!

 

-Chris

[Marc Zeitlin]

That's good to know. But does that imply the airframe is weight limited by the gear at the normal 1425 lb?

First of all, note that the LE POH states that the MGW is 1325 lb., not 1425 lb. This was what the aircraft was originally designed for. The 1425 lb. MGW is the TAKEOFF WEIGHT ONLY, and only under certain conditions (See pages 30 and 39 of the POH).

 

The limitations on either aero or structure that created the MGW in the POH for the LE of 1325 lb. are unknown and unavailable, even to us here at Scaled with access to the designer. Not only that, but the V/N diagram and Vspeeds for the LE are inconsistent with the G-load limits in the POH.

 

All that said, anyone who operates their LE above the published MGW should be (but I can guarantee you isn't) aware that they are reducing their allowable G-loading and changing their V-speeds. Flying the LE at 1700 lb, rather than 1325 lb., lowers the theoretical maximum G capability from 5 to 3.9, with an unknown effect on all of the structural elements of the airframe.

 

Now, there have been no structural failures of LE's, even ones commonly flown overweight, and the 3.8 G limit, if real, is still ~ the Normal category limit. But that's only good for wings, spars, etc. - who knows what the limit is for landing gear and other structures? Maybe folks are destroying nose gear systems because they're flying overweight on a constant basis.

 

Your questions are unanswerable. Folks building/flying LE's at Scaled cannot answer these questions, and if we can't, no-one can (without a full analysis and test program for the aircraft). Anyone that flies over-gross (and that's 1325 lb, not 1425 lb) is relying on an unknown margin and safety factor to cover their ass. So far, no one has gotten bitten by major structural failures (but performance obviously suffers as weight increases).

 

You will never find out whether it's the spar, the landing gear, the nose gear, the seats, the aerodynamic flying qualities, flutter, vibration modes, or anything else that was/is the driving factor behind the limits of the aircraft, either structural (MGW, G's) or aero (Vne, Vmo, etc.). This is because no one knows, and no one has the data with which to know. Get used to this in this business - there's a lot of info that we, as engineers, would like to know that we never will.

 

So, basically, subtract the empty weight of your aircraft and 300 lb. of fuel from the 1325 lb. that the POH proscribes and you will have the amount of weight that you can carry. Obviously, if your plane weighs more than 800 lb. empty, you'll have a hard time carrying anything with full fuel. Since most LE's come in around 900-1000 lb., they're almost always flying at or over the original design MGW. Also remember that there's no requirement to fly with full fuel.

 

Good luck.

[Arbiter]

Marc,

Thank you for your input. As always, you make things many of us are unable to articulate more clear. That said, my original question was what is the useful loads people have on the LE's. Yes the POH says 1325 or 1425 TKO Max weight, but like you said people haven't been bitten yet, even with decreased G load capability and changes in speeds. I have looked at the forum and seen wide ranges in speeds and engines people have that exercise this design (Though you are right, we don't know how much), and I am trying to get a good cross-section in this thread of what people's planes ACTUALLY weigh and what they ACTUALLY carry in "safe" operation. Let me qualify that safe operation to me means they've been flying with these loads for a while now and feel comfortable themselves with these loads. With that spirit, I humbly request more data points for long EZ weight and engine data . Thank you for the posts so far, and we must all keep in mind what Marc says, the design clearly has limits we cannot know at "off-plans" conditions, and we clearly have people flying outside of those limits with success, so I'd like to hear you sound off!

 

-Chris

[TMann]

....and what they ACTUALLY carry in "safe" operation.

1325 lbs.

To insinuate that any greater weight is acceptable would be less than responsible and would endanger other builders who might accept a greater weight as within bounds.

 

You can only get away with flying in ground effect for so long.

[Marc Zeitlin]

... I am trying to get a good cross-section in this thread of what people's planes ACTUALLY weigh and what they ACTUALLY carry in "safe" operation. Let me qualify that safe operation to me means they've been flying with these loads for a while now and feel comfortable themselves with these loads...

While you're collecting this data, also find out what CG range these people use at these weights and what G-loading they've subjected their aircraft to when loaded to their MGW, and what testing they did at those weights to what G-loading at what CG position.

 

What you'll find is that most folks haven't done this testing, have no idea what their aircraft's stall speed or stability criteria is at their MGW at rear CG limit, and therefore the claim of "safe" operation is a, how to say, "canard".

 

Someone can tell you that they've flown their plane for 10 years with a MGW of 1750 lb. and never crashed it. If all they do is 1G to 1.4G cruise and have never hit a 50 fpm gust while at 170 kts., have never done 60 degree banked stalls at MGW and rear CG, have never done stick rap flutter tests at Vne at high altitude while at rear CG at MGW, etc., etc., etc., you know absolutely nothing about the "safety" of the aircraft.

 

This is something that many folks have a severe misconception about - that extended periods of undefined operation imply safety. Exercising the aircraft to the extremes of the envelope is what implies safety - not how many hours you've got at 1G on calm days. Not only that, but someone's "feeling comfortable" about something is in no way an indication of the actual safety of performing that something.

 

Again, I wish you good luck.

[Arbiter]

The Pilot Operating Handbook says 1425 is acceptable for take-off.... That's higher than 1325. Waiter is flying @ 1700 lbs... I am assuming he feels decently safe or he would not fly like this (and I am assuming he wouldn't post something he feels would be un-safe)... Please folks, just post your numbers and Qualify them as you feel you must (Waiter said his runway length increased for example) to ensure people understand the potential differences of your situation (Large engine, bigger retracts, wanton dis-regard for one's self, etc...).

 

Bottom line is we don't know if it's safe or not... We know it's not recommended per the POH, but that assumes a stock LEZ, which may have a smaller engine etc... that's why I'd like to learn what other people have done scuccessfully. Please post weights that you use regularly. If you use 1325, let gross be 1325 for you. If you have flown at higher weights than that and feel comfortable with your design, please post your weights. Thanks!

 

-Chris

[longez360]

The Long EZ POH is for a stock O-235 Long EZ, specifically 79RA. When you build a Long EZ, it will be different and the POH needs to be amended for your aircraft.

 

I have a letter from Mike Melvill which discusses operations over 2000lbs being limited to the gear bow on the bass of static load test data, and high gross service history (Koch, Roman, Rodewald, Rutan, Melvill).

 

E.g.

Long EZ (N169SH world flight) ramp:

Empty (estimated): 1000lbs

Fuel (main): 52 galsUS = 312lbs

Fuel (slippers): 50USgals = 300lbs

Fuel (back seat, estimated): 20galsUS = 180lbs

 

= 1792lbs, no pilot or baggage...

 

 

I have flight tested out to 1975lbs.

 

VH-WEZ (formerly N360WZ)

Empty: 1006lbs

Full fuel: 50gals (US) 300lbs

Pilot: 260lbs

Passenger: 240lbs

 

That's 1806lbs as I flew from the desert Australia back to Mangalore (540nm). OAT was 100F on the ground at Leigh Creek. I averaged 196KTAS, 10500ft and burned 100 litres. Flight Time was 2:45. Around 36 litres/hr.. Turbulence? My backseater hit the canopy a couple of times - woke him up! I slept well that night knowing how good these machines are...

[Waiter]

As a followup:

 

The numbers I originally mentioned are for my original Great American fixed pitch prop. and the standard fixed main gear. When I added the MT prop, this significantly improved the runway performance, at all weights.

 

I originally licensed my LongEZ as 1650 gross wt. As was mentioned, the Landing gear bow is a significant factor. As the plane gets heavier, the risk of a prop strike goes up

 

Also, As Marc mentioned, the proof is in the flight testing. Phase one for my EZ include light, Med and gross wt envelope expansion. The very upper right corner of the envelope included 1300 lb, 1500lb and 1700lb flutter testing to 260 kts with a 2G dive recovery, using a mid range CG.

 

Followup testing was performed at an aft cg (My MT prop moved me to the aft limit) at 1700lb gross wt.

 

I normally fly my plane at the aft CG limit. I also routinely fly my EZ at all corners of the envelop. I regularly fly aggressive ACM and Aerobatics.

 

Two demo manauvers that demonstrate the docileness of the canard:,

 

1)slow flight with bobbing canard. Full power and slowly bring the stick to full aft, at about 55-60kt the canard will start doing its gental stall/recovery at about a 3 second rate, with no dutch roll tendancies, and no divergent tendencies from abrupt control inputs.

 

2) Full G load canard stall, This occures at about 160 kts, in a steep bank, with full aft stick deflection. depending on wt, I can maintain a continous 5 G load, During this manauver, the Canard will be doing a very aggressive stall / recover, about a 1 second rate.

 

Waiter

[Marc Zeitlin]

... The very upper right corner of the envelope included 1300 lb, 1500lb and 1700lb flutter testing to 260 kts with a 2G dive recovery, using a mid range CG.

 

Followup testing was performed at an aft cg (My MT prop moved me to the aft limit) at 1700lb gross wt. I normally fly my plane at the aft CG limit.

John, you are one of the few that actually tests their aircraft. I applaud you for it.

 

You're well aware of the discussions on this and other fora/mailing lists in which folks wave their hands around, state that they flew the plane at mid-CG, mid-weight for 40 hours, did no stall testing, flutter testing, stability testing, climb testing, or pretty much anything, and think that they've proven their aircraft.

 

This is certainly not confined to canard folks - I can't tell you how many homebuilts of all types have this type of "testing" done.

 

I have flight tested out to 1975lbs.

What is your definition of "flight testing?"

 

Turbulence? My backseater hit the canopy a couple of times - woke him up! I slept well that night knowing how good these machines are...

Hitting the canopy can occur at anything less than zero G's. Let's say that you hit a +2G/-2G gust - that's +3G's or -1 G's on the airframe (well below the FAR limits, especially at the speed you were going). That would be a pretty damn good whack on the canopy. It would also be nowhere near the design limits of the aircraft and does not prove anything about how "good these machines are".

 

Understand that I fly one of these planes (a COZY) because I BELIEVE in the structural integrity of the aircraft, and say repeatedly that NONE have ever failed structurally if built to plans. But without knowing the margins, I hesitate to make changes of MGW in the 50% range without engineering assistance. My COZY has a MGW of 2155 lb - 105 lb above the book value. This is ~5%, and I AM an aeronautical engineer. There are otherwise stock (structurally) COZY's out there that fly at 2300 - 2500 lb - I worry about those folks, and that's 10% - 20% over book.

 

1900 - 2000 lb is 50% over book MGW for a LE, and was done by Mike Melvill with just a little bit of engineering support from the original designer.

 

I'm not trying to interfere with Chris' data gathering - just trying to ensure that folks understand what the data means (which is the whole point of gathering, it, I hope).

[longez360]

HI Marc, my definition of flight testing was envelope expansion throughout a defined CG and weight range I planned to fly within. It was certinaly not to the requirements of FAR 23 or to other regulatory authority requirements aside from an FAA 40 test program. I am familiar with the scope of FAA and CASA requirements. It included what testing was deemed fundamental to safety, and that which was acheivable by a homebuilder without an expensive, instrumented, all-encompassing flight test program. It was supported in scope by my flight advisor (ex-Navy Test Pilot school pilot), FAA recommendations for homebuilts, my own experience and the knowledge base behind some commercailly available test literature.. The result in reality is a very limited envelope as I'm certain you elude, and associated risk. It certainly does not account for any environmental scope, and therefore transient accelerations via wind gusts. I simply get a weather brief and stick to Vra as tested when I can.

 

"How good these machines are" is a qualitative term followed by a smile, and was not meant to be a quantification, as I too am an aeronautical engineer. :-)

 

The designer could probably provide engineering support to Mike's aircraft as it probably was more of a 'known' structure against the prototype; same materials used (aside from spar caps), resin & cure specifics (same Mojave environment), and it was built by the same person that was involved in 79RA. 26MS also has s-glass spars. I doubt that is applicable to many other EZs aside from perhaps Dick Rutan's old aircraft. The design allowables would certainly be different for all aircraft as are the aerodynamics etc etc

 

Great chat.

 

Cheers

[Marc Zeitlin]

HI Marc, my definition of flight testing was envelope expansion throughout a defined CG and weight range I planned to fly within....

Excellent. If everyone would do stall, stability, flutter, climb, glide, and performance testing to the limits of the CG range and flight envelope, we'd all be better off. As you state, there's no reason to have to follow the FAR's - we're not certificated. But there IS reason to explore the full operating envelope, and most don't.

[Juhl-EZ]

snip, snip, snip.... and I am trying to get a good cross-section in this thread of what people's planes ACTUALLY ...... snip, snip, snip..... I humbly request more data points for long EZ weight and engine data

-Chris... end snip

Based on data supplied by CSA I have done a small Long-Ez weight study, mainly to find the impact of the use of the popular O-320 engine option.

 

So please find som digest data points.

 

Based on data for 92 nos. O-235 powered vs. 107 nos O-320 powered versions of the Long I found that:

 

• O-235 Long-Ez, average weight 896 lbs (Max. 1050 lbs/Min. 791 lbs)
• O-320 Long-Ez, average weight 961 lbs (Max. 1084 lbs/Min. 845 lbs)

I have done simple 'data wash' like removing what is (hopefylly) typos like a a 400 or 1400 lbs empty weight.

 

Now go figure based on Marcs accurate numbers from the POH and you will conclude that most LE are flown significantly over gross.

 

And its not simple to estimate what *real* resserve is hiden in Burts design. This would have to consider such 'simple issues' as structural strengt including buckling of structures with unknown imperfections (read builder competence, variances in dimensions and material properties among other) and structure/flow interaction (Flutter)

 

Everyone are free to make up their own opinion on the subject (including that on MTOW) but beware that you will most likely only know the 'true' limit by means of the first NTSB report.

 

I guess this is where the the 'Experimental' part comes in

 

Safe building,

Henrik

[Arbiter]

Wow, there are a great many posts in here, and good discussion about the potential concerns very well educated people have about flying over gross. I agree with everything that has been said so far in terms of being cautious when flying over-gross and if possible, executing a test plan to know your limits. That said, what Juhl-EZ has posted shows that at least the airframe of a number of LE's have been successfully flown at higher empty weights, and Waiter has shown he flies near 2000 lbs. With Marc's discussion on decreased G loading and V speed adjustments, it seems prudent to execute a more extensive flight test program to determine the safe operating envelope of the aircraft. I am hoping from the discussion that I will be able to remain under the 1000 lb mark for the structure and maybe try to allow 270 lb pilot, 200Lb pax and partial fuel and see where we get. Please keep data coming as you are willing to share it, bearing in mind the great discussion above. I know I certainly appreciate everyone's thoughts so far as they are candid and presented with detail so the community can understand fully where the data is coming from! Thanks again!

 

-Chris

[Phil Kriley]

Maybe you should consider building something more suitable to your needs. Perhaps a Stagger EZ might be a better fit?

[Arbiter]

The Long EZ is suiting me just fine so far given the data we have here. Probably will have an up-graded engine and be a bit over-gross, but I am not expecting 1100 lbs useful load like Cozy either :-P, probably ~ 810 lbs useful with 2 pax, bags, and fuel which is within experience (At reduced G Loads and V Speeds for rough air). If I was to go full fuel and all the bells n whistles I'd be at 270 (Pilot)+220 (PAX, not the wife , she's much lighter )+20lbs (Bags)+300lb (Fuel). I wonder if you could stick COZY wings and Canard on LEZ Body , just a thought, but perhaps for another thread . I wouldn't likely carry full fuel either since pit stops are more frequent. Thanks for the comment though! I am sure this will generate more discussion so keep it coming!

 

-Chris

[Lynn Erickson]

The Long EZ is suiting me just fine so far given the data we have here. Probably will have an up-graded engine and be a bit over-gross, but I am not expecting 1100 lbs useful load like Cozy either :-P, probably ~ 810 lbs useful with 2 pax, bags, and fuel which is within experience (At reduced G Loads and V Speeds for rough air). If I was to go full fuel and all the bells n whistles I'd be at 270 (Pilot)+220 (PAX, not the wife , she's much lighter )+20lbs (Bags)+300lb (Fuel). I wonder if you could stick COZY wings and Canard on LEZ Body , just a thought, but perhaps for another thread . I wouldn't likely carry full fuel either since pit stops are more frequent. Thanks for the comment though! I am sure this will generate more discussion so keep it coming!

 

-Chris

the long ez wing is the same as the cozy 3 wing. the cozy IV has the same wing outboard of the strake, the difference is in the spar length and the fuselage width. the span is 2 feet longer but the fuselage is 2 feet wider. the only gain with the longer spar on a long ez would be slower roll and slower plane. the extra width and wing span do make a big difference in top speed if powered by the same engine. A Cozy IV with a IO-360 will go 200 mph and a long ez with the same engine will go 240 mph

[SAF_Zoom]

Is the Cozy MIV spar and wing construction the same as that of the LE (other then the lentgh)? Or do they differ. If they do what are the main difference (i.e. different composites/foams etc...)?

[Arbiter]

Is the Cozy MIV spar and wing construction the same as that of the LE (other then the lentgh)? Or do they differ. If they do what are the main difference (i.e. different composites/foams etc...)?

That was what my question was going to be. When I looked at the Cozy initially I saw the 1000 lb useful load, and from discussion I saw the wings were the same with exception of the strakes (Aerodynamically at least) and so I deduced incorrectly it seems that both aircraft would have roughly the same useful load. Could someone with more knowledge than I go a bit deeper into the differences between the Cozy Useful Load and the Long EZ? Thank you for all of your insights so far!

 

-Chris

[Marc Zeitlin]

... Could someone with more knowledge than I go a bit deeper into the differences between the Cozy Useful Load and the Long EZ?

Wing, main spar, canard, landing gear structure are all different. While the wing airfoil may be the same, what's inside of it is not. Same with the Roncz canard. The LG hoop and attach structure is completely different. All were redesigned for the COZY MKIV.

 

And although Lynn is absolutely correct that the wing (by itself) of the COZY III is identical aerodynamically and structurally to the LE wing, the center spar is not and the LE is a 5 G aircraft, while the COZY III is a 3.8 G aircraft. The MGW of the COZY III is 1650 lb., IIRC, at the 3.8G level. You can see what this starts to imply for flying LE's over the original MGW.