rhofacker

I am only in the conceptual stage with this right now, which has me looking at what it would take to cut a foot+ of longeron and to be able to replace it without loosing any strength. As you also point out, forces on the side is another concern. How about reinforced or stronger longerons -- assuming the hole (door) is replaced to allow 100+% of strength to be restored relative to the original plans specifications?

 

Ready? Begin.

If you mean "replace it" by "closing the door" I'd worry about adequately transfering loads through the latches and hinges. I am still thinking along the lines of some sort of structural canopy bow (similiar to the roll over structure already mentioned) and strengthened turtle deck/cabin top. The bottom longerons remain in tact, the bulkheads remain in tact, and fuselage bending and torsion loads are carried around the door cutout to the aft fuselage. the door itself would be "non-structural"

I'll try to describe my "cocktail napkin sketch". Looking at a top view of the fuselage. consider an "X" with one end of the legs attached to the top longerons just forward of the front bulkhead and the back legs of the "X" attached at or near the seat bulkhead. This aft attach point would have to be "adjusted" to minimize passenger engress/egress obstruction and to maximaxe pilot/copilot side view. Looking at a front view, the structure would arch up over the cockpit. The "X" structure could be fabricated by laying it up inside the canpoy just like the previously described Long Eze roll over bar. Pop it loose from the canopy for installation on the fuselage, install the canopy (at least semi permanently) and cut the sides and canopy to make the door...

Simple, Right? knock it out in a weekend (not)

The devil is in the details

This is incorrect. When clean, the GU has a higher maximum Cl than the Roncz, and also lower drag at higher Cl's. The GU (at least as implemented on the V.E., L.E., and COZY) did not have any external "tabs" for trimming the elevator loads, any more than the Roncz does.

 

Nat cut the canard length due to his interpretation of deep stall considerations, NOT because the Roncz airfoil allowed it. In fact, when clean, the GU would have had an even worse effect on the deep stall tendency, due to it's ability to operate at higher Cl's, and would also have required (in Nat's view) a canard shortening - possibly even larger than the existing shortening.

 

The Roncz has much better Cl and Cd characteristics when dirty (but neither airfoil likes to operate this way).

Here is a quote from CP-43 Jan. 1985. A reliable source:

"This completely new and never flown before airfoil is by far the best we have seen. It has a negligible rain trim and the rain only adds 2 knots to stall speed. Of course some more flight testing remains to be done, however, we are confident that we do indeed have what we have been looking for. The R1145MS produces considerably more lift than the original GU—5(11)8 airfoil, and in fact more than any we have tested so far. This enables us to reduce the span, reducing whetted area, and thus drag. The basic airfoil is also very low drag. Its trailing edge shape provides the correct stick forces without external devices."

Republic sea bee has a sliding battery tray to keep plane in CG depending on passingers.

I was wondering. If a Cozy pilot flying solo point "A" flys someplace, and picks up a friend point "B", leaves his ballast there. Flys friend to point "C", and drops him off. Where or how does he get ballast to continue his flight solo?

Just thinking.

Use water balast. dump it when you don't need it, fill it just the right amount when you do need it.

-- GPS: A homebuilt with only a GPS installed would not be legal for IFR operations. Per Part 91.205(d), you must have the other "two-way radio communications system and navigational equipment appropriate to the ground facilities to be used. If you're going to file /G, your GPS and its installation must be certified for enroute navigation and if you want to shoot approaches, certified for terminal and approach navigation.

....Wayne Hicks

Yeah, I see what you're saying: "your GPS and its installation must be certified for enroute navigation" That means: TSO-C129 certified (that makes sense). Now about that installation. If you bought the homebuilt the installation must be accomplished by Type Certificate, Supplimental Type Certificate, or Form 337 just like any other store bought airplane. That means your installation would have to be installed by an A&P and approved by the FAA and have appropriate justification on the Form 337 (similar acft, etc.) and that might mean getting a "First Time Air Worthiness Approval" (MUCH testing )depending on the GPS and the airplane and if it's been done/approved before.

But what about an airplane you built yourself? In general do you need 337s for major alterations and repairs to an airplane you built yourself? How do you get an STC for an airplane you built yourself?

We need a lawyer to explain all this Help!

It seems the GU in the rain thing is a non event, if you do this...

 

http://www.cozybuilders.org/newsletters/news_68.html#GU%20CANARD%20TRIM%20CHANGE

 

http://www.cozybuilders.org/newsletters/news_67.html#gu_canard

 

So other than the rain does the ronz beat the GU in any other way?

Might we consider the GU as a performance upgrade?

The RONCZ 1145 is higher lift so it can be smaller and lower drag. Also does not need any external tabs to balance control loads.

So, to fly IFR enroute, terminal and non-precision approaches I need a GPS certified to TSO C-129 Class A AND an aircraft specific certification by the FAA of the installation? (i.e. UPS GX-50, King KLN-89B, etc.)

I didn't see any info on whether or not the Blue Mountain (et. al) EFIS "GPS" was certified to the necessary TSO C-129 Class A for an IFR certified installation. Any body know?

Anyone know if it's leagle to fly IFR using uncertified EFIS (e.g. Blue Mountain, etc.) as primary flight instrumentation in homebuilt/experimental aircraft?

...just thought I'd trow in some observations

I've never gotten a ride in a Cozy, but any way...

I did get a very brief ride in a Lancair in the right seat, side stick controler in the right hand. This was very comfortable to fly, but I was just a little bit concerned about using my right hand to copy clearances, fold maps, etc. My good ol' Bonanza has a throw over yoke. I'd always thought this was a good compromise: when I'm pic, I can fly with either hand and still have a hand free to set radios, fold maps, copy clearances, etc. When my wife flies we just throw the yoke over and she flies... But, I was supprised to learn my wife is not real comfortable with this arrangement! She worries about not being able to get the yoke back to the other side or getting stuck part way over. She's never once mentioned it to me... She told a friend she was thinking of buying a dual yoke conversion for me for Christmas .

One thing I really liked about the Lancair side stick was the unobstructed view of all of the panel space. I think this would be true in the Cozy as well. The down side is the reduced accessiblity to the control stick by the other hand. This may not be an issue in the Cozy if the plane is stable enough that you can just release the controls for a reasonable length of time even in turbulence.

This is just one (more) reason I'd like to get a ride in a cozy and talk to some experienced Cozy pilots befor I commit to cockpit arrangements (i.e. PIC on left or right, panel lay out, etc., etc.) So, all you experienced pilots out there: how long are you comfortable steering with your feet without your hand on the stick? in turbulence?

One of the claimed benifits of the canard configuration is extreemly good pitch stability even in turbulence. I can't remember if the CAFE fligh test addressed this or not. I'll want to think these human factors kinds of questions through carefully later on when I get closer to making the choices That's gonna be a while...

Just curious: any canard builders out there who are also Hams?

...like to set up a schedule?

I'm W6ZSL...

Sounds like we're pretty much on the same page

While I really like the gullwing door for ultimate sex appeal I haven't rulled out a side hinged door like an automobile. The instrument panel bulkhead would make a convenient hard point for the hinges, no lift struts would be required, etc., etc... we need to think and talk about it some more.

I think you're on to the right time to incorporate the mod: My thinking was to cut the fuselage sides along the forward edge of the seat back, along the top of the bottom longeron, and along the aft edge of the instrumnet panel bulkhead. The thinking is to keep the seat backs and front bulkhead as part of the load bearing structure bonded to the fuselage sides. The down side of this concept is rear seat entry

I'm also not opposed to a center spine of some sort. It makes a convenient place for wiring, control push/torque tubes, and the like. Both my wife and I are not terribly BOB (broad of b$##) I'm 5'5" and my wife is 5"0" so we could afford to give up a little bit of cockpit width.

More Thoughts???

This cannot be denied. After getting in and out of a Cozy for several stops, and not trying to scratch anything or step where I shouldn't, I couldn't help but thinking about what it would take to retrofit a door into the existing design.

 

My inner engineer thinks this can indeed be done. What do you think?

Yeah, I gotta agree. My inner engineer thinks it can be done too. The trick will be doing it without increasing the weight or decreasing fuselage strength. Remember loads are carried in the skins and we're talking about cutting big holes in the side skins. I'm still doodling back of the cocktail napkin stuff and mulling over load paths... I believe that such a mod would be a great interest to many Cozy builders if it were well engineered. Perhaps those of us who are serious about the concept could kick arond some ideas and ultimately share the cost of getting some real structural analysis done. This certainly isn't something I'd want to "eye ball" engineer

One of the side benifits of my noodling is a "roll over" structure that would help protect your upper body in the event of flipping upside down after an "uncontrolled return to terra firma"

adding something like this to an already built fuselage would seem to add another order of magnitude of complexity to the problem

There used to be a canard organization called, I think, "Central States" that kept a web page canard.com. That page appears to be gone Does anyone know if Central States is still active? and how to get in touch/join up with them? They were a great source of information and connections

I'm doing a little planning ahead - thinking about going to Rough River this fall (October?). Anyway the wife and I would be flying our '51 Bonanza from Friendswood Texas on Sat. and returning Sunday. If you think you might like to ride along drop me a note

Oh really?

I have one in my hand. Says "Private Pilot's License" right on the cover.

Oh really???

Mine says "THIS CERTIFIES THAT...", and has a "CERT. NO.", and says on the back, "This certification is of such duration..." I don't find the word "license" anywhere on the AC Form 8060-2 (5-81). Maybe mine is so old that they've change them

I was just looking at the specs of thte E-Racer and the Cozy.The Cozy info pack lists its wing span as 28.1 ft and area as 88.3 sq.ft. The E-Racer is listed as having a span of 26.2 ft and 94 sq.ft of area. I thought both of these designs were derivitives of the Long eze and had the same wings and canard. Anybody know just what the facts is?

Are there other significant differences in the lifting surfaces? Airfoils? Wing twist? etc., etc.?

The CAFE foundation did an evaluation of the Cozy. Does anybody know if they've done one for the E-Racer? If so, would you know which issue it was in?

There are some other differences in specs: Cozy gross weight 2050 lbs, E-Racer gross weight 1800 lbs. Cozy take off/landing @ gross 1700/1300. E-Racer t.o./landing 1200/1500. These differences could be attributed to weight and hp.

Interestingly enough both claim a cruise speed of 220 mph even though the Cozy is 180 hp and the E-Racer is 240 hp! I can't recall off hand what the CAFE report said about the Cozy speeds. If the Cozy advertisement is correct, it's in the ball park with 300 hp Glassairs WOW

Can you get more takeoff performance by trading a bit of cruise speed?

 

Not sure I'd do it, I'm firming up on the ridgy-didge "as per plans" concept. It will still be my baby if it looks exactly like Nat's.

...maybe...

A big part of the take-off performance airfoil problem appears to be reynolds number. The Eppler airfoil looks like it gives a lot better L/D at airspeeds around 60 kts than the low drag laminar sections. Thick sections and large leading edge radiuses (radii?) produce more lift at low reynold numbers and higher drag at cruise Cl and reynolds numbers. There might be some thick, large LE radius, highly cambered airfoil that would do it. But the design trade offs would be a lot more than just higher drag at cruise. Based on the library of airfoils available in this software it looks like Eppler has gone just about as far in that direction as worthwhile. So it looks to me like if you want better take off performance you need more thurst hp... (better acceleration, more power to overcome the drag associated with more lift, etc., etc.)

Even as "per the plans" there is still plenty of oppertunity to customize/personalize your baby.

I have found my answer, and then some..............

 

Thanks for the thoughts expressed in this "Thread".

 

I also found this in Newsletter #75...............8/27/01

Builders,

 

Gull-wing doors are not a good idea. They are not a good idea on the Velocity either. I have heard Danny Maher (original Velocity designer) criticize the doors. To create the gull-wing doors, the upper longerons have to be cut. This destroys the torsional and bending moment path from the main wing to the canard. The effect is the main wing "leads" the canard in a turn. The torsional and bending stiffness cannot be replaced because the stiffness is a cubic function which depends on the distance from the outer most skins. A center trunion like in the Velocity can help, but cannot make up for the loss. IMHO, because of the overall differences between a Cozy and a Velocity, gull-wing doors on a Cozy would be dangerous. The entry/exit can be made comfortably with the powered nose lift.

 

Paul Krasa

Long EZ

 

 

 

Marc.........Seems exactly like what you were saying.

 

Thanks again for the input.

Joseph Spirit

Even so. The Velocity has the easiest ingress/egress of any of the canard types. Yes, it was necessary to reinforce some fuselage structure. But the results are worth the effort.

Davincy Technologoes, the makers of AirplanePDQ software, have a really neat program call Airfoil Optimizer. You input the baseline configuration of your airplane performance and airfoil and it allows you to compare peformance changes with other airfoils from an extensive library.

I plugged in the Cozy MkIV as a baseline and found that while there are airfoils in the database that would improve cruise speed they hurt take off performance. Looks like Mr. Rutan made a very good choice/tradeoff. Imagine that.

Still, it's fun to look...

Ivo has a VERY bad name in the canard community - some of it deserved and some of it not. The basic problem has to do with shedding blades. Basically, the blades are not structurally connected to each other. Each blade has two bolts holding it on the airplane, and there is a gap (however small) between adjacent blades. This is a fundamentally shaky situation, that can be alleviated (if not eliminated) by meticulous and frequent torquing of the blades. To monitor blade relative movement, there is a piece of tape across the interblade gap of each blade that is to be inspected on preflight. If the tape is broken, the prop is hard down until the PROBLEM that CAUSED the tape to break (the blades to separate) is corrected.

 

The serious problems (as in accidents) have all occurred on O-360 engines that are notorious for vibration and torque reversal. These conditions are much reduced on a 6-banger, and virtually nonexistant on a rotary with redrive. Pusher applications involve much more flexing than tractor applications

 

The most infamous fatal accident involved a Velocity that had the pitch motor run away to full coarse pitch. The guy field stripped the prop, disconnected the motor, ground adjusted the prop to fine (T/O and climb) pitch [improperly I hear], reinstalled it [improperly I hear], torqued it [improperly I hear, or not at all] and launched on a longish (three hour or so) flight at night. The prop shed a blade and he and his family were killed. There is no doubt that he was flying on instruments (in the sense that there's no visual reference to the horizon when you have your head up your ass...) but the fact remains that a Performance or Catto prop CANNOT shed a blade unless you break it by passing a large, structural object (a Catto prop has survived the shedding of the lower cowl of a Long-EZ) going throuh it.

 

The design is fundamentally delicate. This can be Compensated for, but I personally would prefer a product that doesn't require so much compensation. From a performance perspective, it is pretty marginal as a "variable pitch" prop since only the outboard portion of the blade (that is physically twisted by a torque rod driven by the electric motor) changes pitch. At high/course (cruise) pitch, the inboard portion of the blade can have zero (unproductive) or even negative (counterproductive) AOA. The "magnum" prop is aleged to reduce this effect, but it's still there even if it is less prominent.

 

At this juncture, I plan to fly my rotary Cozy with the Catto prop from hell - very wide chord and pitched from here to yonder.

 

Just a theory ... Jim S.

uhmmmm...

"...the blades are not structurally connected to each other..." in ALL adjustable/constant speed props that I'm aware of.

"This is a fundamentally shaky ("shakey" was an excellent choice of words here )situation..." exists for ALL adjustable/constant speed props that I'm aware of. I suspect that the fundamental problem is one of vibration/torsion resonance. Matching a prop to an engine is not a simple "bolt it on" issue. Yes, many pops ahave the resonance frequency well out side the operational range. But, for my money a dynamic balance check at all operational RPMs is a minimum requirement for prop/engine installations

...hhhmmmmm....

I did a quick search on the NTSB database for IVO prop and found only 4 reports between 1/1/89 and 5/18/2004. 3 were engine failure and one was a Darwin award to the pilot. None were prop failures. I've been seriously considering thte IVO prop but now you've got me worried

I think it was Socrates who came up with the three point plan for passing on rumors 1) do you know it to be the truth? 2)is it derogatory? 3) does it benifit me to know?

Can anyone point me to some facts about the IVO prop?

I have read that the Cozy canard airfoil is the Roncz 1145. What is the Cozy main wing airfoil? I think I read somewhere that it is an Eppler e1230. Is that correct?

...just wondering...

What are the trade offs for high, mid, or low position of the canard relative to the wing? Looks like the Veri easy (long easy) spin-offs have the canard either in line with the wing (mid position) or slightly above the wing (high position). The Q2s/Quickies have the canard below the main wing (poor description in this particular case). What would be the aerodynamic effects of placing the canard below the main wing? It would seem to get the canard

down-wash/wake below the main wing for less interference effects.

I've been reading the posts on using peel ply and plastic sheet for laminating. When do you remove the plastic and peel ply? Many operations call for trimming edges when the cure reaches the "green" state. Do you pull the plastic and peel ply at this point or wait until full cure? If you wait for the full cure how do you trim the edges? Trimming excess cloth is a LOT easier if done before the full cure...

I've seen some Epoxy advertised (AC Spruce) called Polly Epoxy. They claim they are the only epoxy to have two cure phases. Any body know what they are talking about? I thought ALL epoxies had two cure phases: the initial cure and a secondary cure occuring after several days.