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Modifying the sides for more width


Jon Matcho
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I decided to split this thread into its own discussion here from the Max width of the fuselage thread.

 

[For more cabin width] put the longerons flush with the outside of the fuselage skin (as opposed to the behind the foam on the inside)

John, I would like to hear more about this mod. It seems like an easy change, however, I haven't found much discussion on it.

My name is Jon -- there's less 'drag' in that version.

 

I've seen the mod discussed and mentioned several times over the years, and will be digging through the COZY mailing list archives when I approach this section in the coming weeks. I don't have anything more to say at this point other than it seems very reasonable and doable, the longeron positions will NOT change, and I'd be happy to share my findings and results.

 

Anyone else care to setup a virtual team to consider and work through this modification? Anyone know anything else about it?

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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  • 3 weeks later...

I've seen the mod discussed and mentioned several times over the years, and will be digging through the COZY mailing list archives when I approach this section in the coming weeks. I don't have anything more to say at this point other than it seems very reasonable and doable, the longeron positions will NOT change, and I'd be happy to share my findings and results.

I've looked through the archives as well as studied the plans for the sides. I was wrong to say that the longeron positions would NOT change, as the goal is to actually move them out flush to the sides.

 

To make this happen I'd have to redo my seatback, instrument panel, and forward bulkheads to provide support for the longerons being set wider than the plans (unless there's another way I don't know about). I'm sure there are other issues to contend with as well. Considering all that, I am going to build the sides per plans with the exception of my widened AeroCanard FG rear.

 

Things you could do to get more shoulder room without substantial changes to the design are then:

  • Use thinner foam (and additional layups?) for the armrests as well as contour more closely to the control rod
  • Do the "Cozy Girrrl Strakes" modification and carve out inside to allow more lower elbow room
  • Substantial Change: Put the longerons flush with the outside of the fuselage skin (as opposed to the behind the foam on the inside)
Anyone have any ideas/tips for what else can be done to make the cabin feel wider?

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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Having not yet studied it from an engineering point of view, I'm not sure I agree with moving the longerons flush to the outside. I would think that the top of the fuselage being curved inward adds rigidity just as a rim on a plastic tub or bucket does.

 

If you want shoulder room, then raise and widen the canopy deck. My shoulder always hits against the inside of the canopy frame first. It never really hits against the longeron. I raised my canopy by 1.75 inches, mostly to get rid of the cosmetic depression between the turtleback and the canopy glass. I widened the canopy by 2 inches, an inch each side. I did that mostly to get the glass away from my face.

 

These two changes make more room at the shoulder.

 

If you want more hip room, that's another story altogether. Except for minimizing the arm and center consoles, there's not much to do except physically widen the fuselage. But if you don't widen the canopy frame, you're still going to hit your shoulder on it.

Wayne Hicks

Cozy IV Plans #678

http://www.ez.org/pages/waynehicks

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I would think that the top of the fuselage being curved inward adds rigidity just as a rim on a plastic tub or bucket does.

Interesting. I'm sure it adds some rigidity as well, but after deep-analyzing this using my hunch-o-meter, I'm not sure the result would be a weak structure considering the torsion box of the fuselage+bulkheads. Still, I bet it would be easier to kick-in the modified longerons than the per-plans longerons.

 

If you want shoulder room, then raise and widen the canopy deck.

I would like to widen the canopy frame, but not raise it. I might be torso-short, or not sitting on enough foam, but whenever I was flying in Marc's plane (ahhh the days...) I was always looking for a better downward view. Maybe I just need to do the front-side windows like Bill James' plane. Maybe Rutan-style port holes would look better?

 

The other thing that's been running through my head for over a year is to actually cut the longeron like was done for this modified Cozy III.

 

If you want more hip room, that's another story altogether. Except for minimizing the arm and center consoles, there's not much to do except physically widen the fuselage.

What's to do to make this happen? Go with an electric landing brake? What else?

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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  • 2 years later...

Hey folks,

I am probably going to be building a Cozy MkIV starting within a year or so. I am a fairly wide shouldered guy and just sat in one of my friends' un-modified Cozy, and it was a little tight. I am interested in the Cozy since it has a lot of modification capability (added strake length via Cozy Girl mods, electric nose gear, RG, etc...) versus the velocity kit. However, a huge sticking point for me is cabin comfort. The Cozy IV as it is un-modified won't fit me, my wife, and another adult friend comfortably (I say this because at full fuel I would likely be pushing the gross with all of us + fuel onboard). So, what I was thinking is going to add 5 inches of extra width at the panel bulkhead, the 1st row seat bulkhead and then fairing down the the original width at the turtledeck/spar area. Though the fuse width would be the same at this area, I would extend the spar 5 inches like was discussed above.

 

The question I have is this :cool2: : Is 3 inches a magical maximum number, or would it likely be alright to do this? I would gladly take the hit to top speed performance as long as it does not kill my climb and gross weight too much. Need to do some more calcs to understand the added weight impact of 5 inches though. Anyone have good resources for doing this particular mod? Thank you all for your time!

 

-Chris Z.

Chris Zupp

~Aircraft Designer~

Preliminary Design Sequence I: Project Endeavour

Aeronautical/Mechanical Engineer

Private Pilot

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You do not say what you and the wife weigh? IF the two of you together weigh over 450LBs. You are over gross and probably better look at another type of plane less sensitive to weight and balance. STeve build on

Steve Harmon

Lovin Life in Idaho

Cozy IV Plans #1466 N232CZ

http://websites.expercraft.com/bigsteve/

Working on Chapter 19,21

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You do not say what you and the wife weigh? IF the two of you together weigh over 450LBs. You are over gross and probably better look at another type of plane less sensitive to weight and balance. STeve build on

Hey Steve,

Together in the front seat we probably would be over, but not by too much. The beauty of home-building from scratch is you have the opportunity to modify the aircraft, and I intend to! Even if I wasn't over-weight I have a lot of thigh muscle from biking and soccer, and when I sat in my friend's Cozy it was a little too snug. I can't afford a Velocity XL, so unless I want to build an Aerocanard which has a slightly wider fuse, I will need to modify the fuse no matter what. Doing the modifications the way another person suggested could buy some space, but I don't think enough, and staggering the seats isn't a design option I am willing to consider at this juncture.

Another option to help the CG is to turn it into a 2 Seat by moving the forward seats aft a fair amount (3-4 inches?) and get back some of that CG problem you were speaking of : ). I'd prefer a 4 seat aircraft, but the 2 seats in the back are not for adults unless they are really tiny.... Thanks for the advice though!

 

-Chris

Chris Zupp

~Aircraft Designer~

Preliminary Design Sequence I: Project Endeavour

Aeronautical/Mechanical Engineer

Private Pilot

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You aren't 'getting' it. No matter how much you want a Cozy IV in your present condition the Cozy doesnt want you.

Theres more involved here than just accommodating your size. Check the archives on the forums...The approved canard design isnt conducive to your weight. Sorry to be blunt, but you dont just make it wider and everything 'works'. Widening adds weight. A electric noselift adds weight. A full panel with all the bells and whistles wasnt in the calculation originally for a light Cozy. And whatever you add to the opposite end of the teeter totter behind the FW, exacerbates the front seat 'problem', electric starter, added oil cooler, etc. Everything adds up. If you START out at 430 to 455....dam...you are WAYYYYY over what the front of the aircraft should weigh, CG wise. This aint an automobile. CG is king, and the balance of lift between the canard and main wing is paramount.

Some have flown at 425# but who's to know what was in or not in their planes. I am sure you dont want to run out of runway on takeoff on a hot density altitude day...and then blame it on the airplane when you hit the chain link fence.

It could ruin your whole day.

With regards to moving the seats around to permanently affect the CG? Do that and you enter a complete new world of testing issues, as you create an unproven design, which is why so many are interested in the PROVEN design of the Cozy. Of course its all in what someone is comfortable with. Which is what this is all about anyway.

The past universal advice has been go on a diet. Thats what I did, just so you know.

Self confessed Wingnut.

Now think about it...wouldn't you rather LIVE your life, rather than watch someone else's, on Reality T.V.?

Get up off that couch!!! =)

 

Progress; Fuselage on all three, with outside and inside nearly complete. 8 inch extended nose. FHC done. Canard finished. ERacer wings done with blended winglets. IO540 starting rebuild. Mounting Spar. Starting strake ribs.

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You aren't 'getting' it. No matter how much you want a Cozy IV in your present condition the Cozy doesnt want you.

Theres more involved here than just accommodating your size. Check the archives on the forums...The approved canard design isnt conducive to your weight. Sorry to be blunt, but you don't just make it wider and everything 'works'. Widening adds weight. A electric noselift adds weight. A full panel with all the bells and whistles wasnt in the calculation originally for a light Cozy. And whatever you add to the opposite end of the teeter totter behind the FW, exacerbates the front seat 'problem', electric starter, added oil cooler, etc. Everything adds up. If you START out at 430 to 455....dam...you are WAYYYYY over what the front of the aircraft should weigh, CG wise. This aint an automobile. CG is king, and the balance of lift between the canard and main wing is paramount.

Some have flown at 425# but who's to know what was in or not in their planes. I am sure you dont want to run out of runway on takeoff on a hot density altitude day...and then blame it on the airplane when you hit the chain link fence.

It could ruin your whole day.

With regards to moving the seats around to permanently affect the CG? Do that and you enter a complete new world of testing issues, as you create an unproven design, which is why so many are interested in the PROVEN design of the Cozy. Of course its all in what someone is comfortable with. Which is what this is all about anyway.

The past universal advice has been go on a diet. Thats what I did, just so you know.

While not endorsing front seat weight figures being more than the recommended and tried figures, and fully endorsing the fact that CG is king, I am compelled to say that increasing the the "back of the teeter tottter ie starter, alternatior airconditionig, jacuzzi etc. does not exacerbate the front seat problem. In fact it is the opposite. At a given CG, as you add weight to the area in back of the CG, you need to add appropriate weight in front of the CG (the amount depends on the relative arms.) In fact adding weight in the back increases the necessity to add weight in front whether lead or adipose tissue (I can say that because I am not as svelte as I used to be). The CG must be within the appropriate range, how you get it there is the question and can be easily calculated.

 

Now as to the gross weight, that is another issue.

 

Many planes fly very well, thank you significantly overgross (witness those with huge aux fuel tanks for ferrying If the CG is correct they will fly.

However there are certain costs for flying overgross,

1. structural airframe considerations (everything breaks if given enough force)

2. Landing gear structural considerations (the main gear isn't supposed to come up unless you designed it that way

3. aerodynamic considerations. ie. lackluster or no climb, slow cruise due to the necessity to fly at a greater angle of attack and less margin between cruise and stall for the same reasons

4. poor fuel economy.

 

Actually the concept of the stagger e-z makes sense here since it will give more shoulder and hip room, retain a semi side to side seating arrangement and it will move the CG rearward because of the passenger's weight being at a station farther aft.

 

Maybe 10 minutes with a thorough knowledge of W&B and a pencil, or computer will give a go or no go sign to continuing to think about the appropriateness of this aircraft.

I Canardly contain myself!

Rich :D

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Hey Steve,

Together in the front seat we probably would be over, but not by too much. The beauty of home-building from scratch is you have the opportunity to modify the aircraft, and I intend to! Even if I wasn't over-weight I have a lot of thigh muscle from biking and soccer, and when I sat in my friend's Cozy it was a little too snug. I can't afford a Velocity XL, so unless I want to build an Aerocanard which has a slightly wider fuse, I will need to modify the fuse no matter what. Doing the modifications the way another person suggested could buy some space, but I don't think enough, and staggering the seats isn't a design option I am willing to consider at this juncture.

Another option to help the CG is to turn it into a 2 Seat by moving the forward seats aft a fair amount (3-4 inches?) and get back some of that CG problem you were speaking of : ). I'd prefer a 4 seat aircraft, but the 2 seats in the back are not for adults unless they are really tiny.... Thanks for the advice though!

 

-Chris

In my aircraft which has the same wing plan form as a Cozy the seats have been moved back 10" and the front seat is limited to 450 lbs. so moving it only 4" won't do much.

Evolultion Eze RG -a two place side by side-200 Knots on 200 HP. A&P / pilot for over 30 years

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You aren't 'getting' it. No matter how much you want a Cozy IV in your present condition the Cozy doesnt want you.

Theres more involved here than just accommodating your size. Check the archives on the forums...The approved canard design isnt conducive to your weight. Sorry to be blunt, but you dont just make it wider and everything 'works'. Widening adds weight. A electric noselift adds weight. A full panel with all the bells and whistles wasnt in the calculation originally for a light Cozy. And whatever you add to the opposite end of the teeter totter behind the FW, exacerbates the front seat 'problem', electric starter, added oil cooler, etc. Everything adds up. If you START out at 430 to 455....dam...you are WAYYYYY over what the front of the aircraft should weigh, CG wise. This aint an automobile. CG is king, and the balance of lift between the canard and main wing is paramount.

Some have flown at 425# but who's to know what was in or not in their planes. I am sure you dont want to run out of runway on takeoff on a hot density altitude day...and then blame it on the airplane when you hit the chain link fence.

It could ruin your whole day.

With regards to moving the seats around to permanently affect the CG? Do that and you enter a complete new world of testing issues, as you create an unproven design, which is why so many are interested in the PROVEN design of the Cozy. Of course its all in what someone is comfortable with. Which is what this is all about anyway.

The past universal advice has been go on a diet. Thats what I did, just so you know.

Ok, clearly you "DON'T GET IT". First off, I'm not 450lbs, I'm 266, so I am not WAAAAAAAAAAAAY over the Cozy fwd CG limits. The number I gave you was 2 grown people in the front, myself and another person. Another point I'll make is that the Cozy fits me, I just want more room, and that's a complaint I see in many posts here. Thirdly, this is a MODIFICATIONS forum, so this kind of stuff should be discussed, not shot at by people who want to stick to plan gospel. If you meant to discuss the issue, the tone of your post needs to turn from pretentious and honestly RUDE to more positive and thoughtful (Take some pointers from the post below yours), especially if you want anyone to listen to you. Despite your tone and rudeness, I will give my thoughts to some of your concerns with the idea of adding width:

 

A.The approved canard design isnt conducive to your weight.

- The design IS conducive to my weight. See above

 

 

B. Sorry to be blunt, but you dont just make it wider and everything 'works'.

- Correct, however, this is an experimental aircraft (plans built no less). A plan is just that, a plan. This is not a production aircraft, it's in the experimental category for a reason.... Many people have made various modifications without increased safety risk to these aircraft. I have been looking through these forums and have seen some very thoughtful discussion on this forum about widening the Cozy. Each design change must be carefully thought through, and that's what I'm attempting to do here. My question was merely why 3 inches wider seems to be a more magic number than the rest (Sweet spot, pusher prop issues, etc...).

 

B. Widening adds weight. A electric noselift adds weight. A full panel with all the bells and whistles wasnt in the calculation originally for a light Cozy. And whatever you add to the opposite end of the teeter totter behind the FW, exacerbates the front seat 'problem', electric starter, added oil cooler, etc.

- I design jet engines for a living, so I definitely understand that adding anything to an aircraft must be carefully considered from a weight perspective. You pay for bells and whistles with decreased useful load and ultimately performance. The question in this case would be probably about 20-30 Lbs of excess weight in structure, possibly more but not much. This is something I am prepared to live with and compensate for in my design.

- Some other issues I want to consider more thoughtfully:

- What is the load change into the fuse from the wings (A la the main spar) and is the structure capable of handling that with safety. This requires some more thought to the added moment and weight the wing must support, but not in-surmountable (My aircraft structures class would finally be useful, and we talked about Composites!)

-Would the penalty in performance from the added weight of the aircraft be worth the modification. This could be compensated for by adding more horsepower, or slightly modifying the wing area (With added drag and weight penalties, but may be worth it) to give more lift.

 

Essentially what it all comes down to is that the Cozy Mk IV is a capable airframe with quite a lot of performance. IMHO sacrificing some of that performance for a little comfort and fit (Especially if I am going to go on a long trip like they say you can) is alright with me. I bet if I built a 6 inch wider Cozy, it would be no less safe than a strictly plans built one. The key is to make judicious changes, and be fully aware of the consequences of those changes, good or bad. In this case, widening the aircraft sacrifices some weight, harder working prop (More horses possibly), and performance for added comfort, something I think the Cozy could use : ) (Ever hear of Robin hood? ;) ). These are just my own ramblings at this point, until I get my plans it's all up in the air. I've gotta go run 3 miles, just like I do almost every day... Check back with y'all later, thank you for the feedback!

 

-Chris Z.

Chris Zupp

~Aircraft Designer~

Preliminary Design Sequence I: Project Endeavour

Aeronautical/Mechanical Engineer

Private Pilot

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In my aircraft which has the same wing plan form as a Cozy the seats have been moved back 10" and the front seat is limited to 450 lbs. so moving it only 4" won't do much.

Need more information??????

 

The planform of the wings merely determines the CL. I am talking about the CG (which is independent of the CL) Of course to fly, there has to be the proper relationship between CL and CG, however CG is not a flying calculation (it is a flyable calculation)

 

1. why is your front seat limited to 450? (I assume it was based on your CG calcs to put the CG where it should be)

2. If your seat were in the per plans position what would your allowable front seat loading be? or better yet, what would your actual (or calculated CG have been (IE with everything else being equal, how much did the CG move back with your rearward movement of the seat.

 

If the proposed rear loading is higher than yours, with the same seat position, the mathematical front loading necessity would be greater than 450.

 

When talking about CG and CG changes with respect to variations from the norm, it would be so much more helpful to all of us if we would, instead of giving resultants ie allowable front seat loading etc. if we give the raw CG facts, ie the actual CG as measured (or calculated) with an indication of the arm changes due to each modification. ie front seat back at Station xxx, pax seat back at station yyy (we, from the plans know where the original station was)

 

The W&B of the empty aircraft (weight and CG-- in or out of the envelope) is really the only important thing here. If we start with the specs of Nat's plane, we can easily calculate the ramifications of moving the seats, putting a longer prop extension or a C/S prop, a lighter or heavier engine, Wet bar under the Canard or any other thing we want to do to the aircraft. The calculations will tell us how much we need to put in the front seat, or what the limit is etc.

 

In 1968 I was flying wood wing Moonys. Their (and the FAA's) idea of W&B was a stapled sheet showing sample loading. No calcs for W&B. We have come a long way since then, lets use the technology in our communications-----please

 

:::disclaimer:::: Lynn, this monologue was not aimed at you. I know that you know all of this stuff. There are however those on this forum who don't really understand the complexity of W&B and perhaps will make serious mistakes based on a possible misinterpretation of statements.

 

I don't like accidents or failures ::::end of disclaimer::::

I Canardly contain myself!

Rich :D

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Together in the front seat we probably would be over, but not by too much.

Ok, clearly you "DON'T GET IT". First off, I'm not 450lbs, I'm 266, so I am not WAAAAAAAAAAAAY over the Cozy fwd CG limits. The number I gave you was 2 grown people in the front, myself and another person.

The front seat weight limit is 400 lbs, correct? That means 400 pounds, two people, total weight up front. Yeah I know, people have flown over 400 pounds up front, I'm just trying to get one small aspect of this argument straightened out.

 

There have many discussions on the possible negative results of widening a Cozy on the internet. The fuselage creating its own lift, and the associated possibilities of a deep stall is an issue.

 

Hey, if you want to widen it, go for it. It may fly just fine. Just don't call it a Cozy. For me, its difficult enough just following the plans and getting everything correct.

Andrew Anunson

I work underground and I play in the sky... no problem

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The front seat weight limit is 400 lbs, correct? That means 400 pounds, two people, total weight up front. Yeah I know, people have flown over 400 pounds up front, I'm just trying to get one small aspect of this argument straightened out.

 

There have many discussions on the possible negative results of widening a Cozy on the internet. The fuselage creating its own lift, and the associated possibilities of a deep stall is an issue.

 

Hey, if you want to widen it, go for it. It may fly just fine. Just don't call it a Cozy. For me, its difficult enough just following the plans and getting everything correct.

Andrew,

We're talking about 6 inches at most (This is probably a lot more than I actually would do) and I would have serious reservations about building a kit that has that little margin in its main wings and canard before the Fuse would generate its own lift and create a deep stall issue over the wings. All together a 6 inch expansion would probably be about 8 sq ft of planform area increase (~10% total planform area) if it was straight all the way back. I plan to expand at the panel bulkhead, the front seat, and the rear seat (but not as much, since it needs to be faired back into the original design) so it will probably be ~2-3 Sq ft increase. The Fuselage generates lift now in a positive angle of attack, so I don't see any real problem creating a deep stall (Someone go into more detail if they have it if I am wrong) by adding 2-3 sq ft of planform area.... The biggest issue I see expanding the fuse would be more centered around the structural concerns (Rigidity, moment, CG etc)... And those can be mitigated at the cost of additional weight spread judiciously around the airframe. You could probably make up most of the performance impact by getting some more horses out of the engine, but those are details to be gotten into at a less speculative time (I.e. when I have plans in hand...)

 

Why are people so worried about this mod? Hasn't anyone heard of a 737-200/300/400.../900! They stretch commercial aircraft all the time with few changes to the structure and size of the wings (They do plan for this though, and so should have Nat and Burt :)). As far as naming goes, sorry, it's a modified Cozy Mk IV, I'm not going to name it anything different!

 

As for the front seat weight limit, I saw on a post in here Nat said that he just arbitrarily put that number in there because it seemed right to him. He probably wasn't far off, but I would venture to guess there's a fair amount of design margin built into that number... It all comes down to CG and structural limits...

 

In the end, I am probably going to expand my plane, call it ugly if you want, but I'd rather be different than gospel Cozy builders (You certainly can't do too much differentiation on paint colors and schemes ;) ) any day. I plan on incorporating Cozy Girrl Strakes in my design as well, that will likely have more lift implications than a fuse expansion even if they are behind the Canard...

 

Is anyone I am talking to an Aerospace/Aerostructures Engineer?

 

Keep em coming, I am enjoying this discussion, and all good points that merit a lot of thought!

 

-Chris Z.

Chris Zupp

~Aircraft Designer~

Preliminary Design Sequence I: Project Endeavour

Aeronautical/Mechanical Engineer

Private Pilot

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Arbiter- I just got home after being gone so I could respond to your post after mine until now. I wont qualify myself other than to say I have been an active builder and not an armchair builder and seen the talk and walked some of the walk.

I apologize for your sensitivity. I am calling at as it is. It just IS what it IS. You cant 'just make it wider and have it "work"' at that FSW. You are not getting it and sometimes thats just the way it is. All these posts since mine and you still feel justified in your 450+ pounds of people in the front seat. As for my 'rudeness'... well as I said, the plane is the plane and thats the way it is. If the front seat is too heavy for performance, it is not I who is controlling the lift.

And by the way, I dont really care if you listen to me, its your 7 years building it, and when it doesnt work the way you want, you'll have forgotten long before about anybody's attempts to bring reality to you about this. Widen away.

Self confessed Wingnut.

Now think about it...wouldn't you rather LIVE your life, rather than watch someone else's, on Reality T.V.?

Get up off that couch!!! =)

 

Progress; Fuselage on all three, with outside and inside nearly complete. 8 inch extended nose. FHC done. Canard finished. ERacer wings done with blended winglets. IO540 starting rebuild. Mounting Spar. Starting strake ribs.

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The Fuselage generates lift now in a positive angle of attack, so I don't see any real problem creating a deep stall

Chris,

You most likely already understand this, but a deep stall can occur if the canard (or anything in front of the main wing) generates more lift than it should. The angle of attack can increase to the point that the canard (or fuselage) may still be creating lift, even after the main wing has stalled. If the main wing stalls and the canard isn't generating enough pitch authority to lower the nose, then there is no way out of the stall.

 

The plans Cozy should not ever get to this point, the Canard (and fuselage) stop generating enough lift to support the front of the plane, the nose drops down, and the speed begins to increase (and the AOA changes of course).

 

The idea here is that extra width (say six inches) of fuselage MAY create enough extra lift in front of the main wing to allow AOA which stalls the main wing.

 

I would have serious reservations about building a kit that has that little margin in its main wings and canard before the Fuse would generate its own lift and create a deep stall issue over the wings.

Well, the original canard width for the Cozy MKIV was shortened by six inches, because Nat was able to enter a deep stall with his unique movable ballast (he was checking CG limits I believe). He prepared for any issues with a sliding weight in a tube that allowed the weight to be quickly moved to the front of the plane to get the CG back towards the front. Nat required existing MKIV owners to shorten their already complete canards.

 

Any changes made to the plans are fine with me (I'm only in chapter 7 though). Nobody here will stop any mods from being done, thats is the true beauty of this.

 

Most builders here and elsewhere agree to call their plane something other than a Cozy MKIV if unapproved changes (such as retract gear or wide fuselage) are incorporated. Nat required it, and most still follow the rules. Nat would not allow a plane to be called a Cozy, unless the plans and associated approved modifications were followed.

 

Extensive testing with precautionary items such as a movable weight would be smart to use to fully test the plane to determine the weight and balance. You can't use the plans weight and balance calculations, because it potentially a different animal. Cozy builders don't use the Long-EZ weight and balance, because its too different.

 

Three inches would be nice, I guess, but I haven't even sat in Canard aircraft yet. One of these days....

 

The wide body Porches looked cool, but the seating area was always kept the same.

 

No, I'm not an aerospace engineer, I was hoping to be able to actually find a job after college. :D But, most here understand the aerodynamics of a canard aircraft, as well as the implications that arise with untested changes.

Andrew Anunson

I work underground and I play in the sky... no problem

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Arbiter- I just got home after being gone so I could respond to your post after mine until now. I wont qualify myself other than to say I have been an active builder and not an armchair builder and seen the talk and walked some of the walk.

I apologize for your sensitivity. I am calling at as it is. It just IS what it IS. You cant 'just make it wider and have it "work"' at that FSW. You are not getting it and sometimes thats just the way it is. All these posts since mine and you still feel justified in your 450+ pounds of people in the front seat. As for my 'rudeness'... well as I said, the plane is the plane and thats the way it is. If the front seat is too heavy for performance, it is not I who is controlling the lift.

And by the way, I dont really care if you listen to me, its your 7 years building it, and when it doesnt work the way you want, you'll have forgotten long before about anybody's attempts to bring reality to you about this. Widen away.

There is a person who widened his Cozy 3 Inches and has been flying fine in my area for a little while now, and others have done it successfully too... Hard to believe it's a real problem... It is what it is...

 

You cant 'just make it wider and have it "work"' at that FSW. Clearly you are not understanding that people have modified this aircraft in the manner I am proposing and have flown, they are not Armchair people. I am at this point, but I know it works (The reality you are talking about) fine, at least with 3 inches, which may be plenty for my needs. I realize that the FSW issue is not solved by the widening, only the cabin comfort is. I'll put the person in the back... Or make it a wide 2 seater :-P (Blasphemy right?) perhaps. We have conflicting philosophies about homebuilts, IMHO the plane is not the plane until it is built, all you get is plans, which is a compass so to speak. If you strictly follow your "google map" you get to your destination, but you may have missed out on the adventure along the way. Yes the end product has to make sense from a physics perspective, and my situation clearly offers unique challenges. I am glad I can see past the plans and help realize a little better design than Burt or Nat's has for my own requirements. Why re-invent the wheel? If I wanted to, I'd design my own aircraft from the ground up to solve my problems, but the Cozy is the closest Canard to my requirements, and I believe I can make it work, and work safely. Believe it or not, Nat and Burt (No offense to them, they are clearly awesome dudes) did not design the PERFECT aircraft, so tweaks are OK, you just have to know the principles and the potential pitfalls and mitigate them... Thanks for your input though!

 

Andrew,

Thanks for the lesson in Deep stall. I'd be curious to know the flight conditions Nat was testing under. In the conditiond of the wider canard, it is a problem since it's so much further forward of the CG, any additional canard area would result in a much higher moment. I am assuming the CG is relatively close to where I would expand the aircraft, and thus the pitching moment would be greatly reduced from that of the canard (The changes might also put some area behind the CG, providing some counter moment so to speak). The lesson here perhaps is if I were to expand the width, I should do it as evenly as possible around the empty CG so when I sit in the pilot seat, the CG moves forward of the new "area created" giving it a slight pitch down moment in flight compared to the plans... This warrants more thought when I get the plans, thanks for pointing out that potential issue! I probably don't want to make the airframe "duckbilled" by expanding only the instrument panel bulkhead. Rather, I would maybe want to expand that 3 inches, and the front seat 4 or 5 and then the rear seat 4 or 5, so that the bulk of the fuse planform change occurs over the CG... Good point! Also, if it's an aft CG limit issue (by your post it sounds like it is) my fat a** will help get the nose down ;) and the aft CG limits won't be a problem ;).... See, there are Bene's here to having a lot of weight in the front... Thanks for the posts guys!

 

-Chris Z.

Chris Zupp

~Aircraft Designer~

Preliminary Design Sequence I: Project Endeavour

Aeronautical/Mechanical Engineer

Private Pilot

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Arbiter:

 

I dont think most people think that widening your fuslage a few inches is going to kill you. I do believe if you put to much weight in the front seat you have a much higher chance of killing your self. If you keep the weight to 400 it is considered safe. I have read about guys flying at 500lbs in the front on accident they forgot to take out their balast when they put a passneger in the plane. It flew alright just kind of different. I sure would not fly with this kind of cg. Read about broken nose struts on the list. The plane was made for 400lbs in the front seat you do what you want but that was what the designer put as the weight limit and that is what I am planning on flying. No more discussion on this build on STeve

Steve Harmon

Lovin Life in Idaho

Cozy IV Plans #1466 N232CZ

http://websites.expercraft.com/bigsteve/

Working on Chapter 19,21

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Need more information??????

 

The planform of the wings merely determines the CL. I am talking about the CG (which is independent of the CL) Of course to fly, there has to be the proper relationship between CL and CG, however CG is not a flying calculation (it is a flyable calculation)

 

1. why is your front seat limited to 450? (I assume it was based on your CG calcs to put the CG where it should be)

2. If your seat were in the per plans position what would your allowable front seat loading be? or better yet, what would your actual (or calculated CG have been (IE with everything else being equal, how much did the CG move back with your rearward movement of the seat.

 

If the proposed rear loading is higher than yours, with the same seat position, the mathematical front loading necessity would be greater than 450.

 

When talking about CG and CG changes with respect to variations from the norm, it would be so much more helpful to all of us if we would, instead of giving resultants ie allowable front seat loading etc. if we give the raw CG facts, ie the actual CG as measured (or calculated) with an indication of the arm changes due to each modification. ie front seat back at Station xxx, pax seat back at station yyy (we, from the plans know where the original station was)

 

The W&B of the empty aircraft (weight and CG-- in or out of the envelope) is really the only important thing here. If we start with the specs of Nat's plane, we can easily calculate the ramifications of moving the seats, putting a longer prop extension or a C/S prop, a lighter or heavier engine, Wet bar under the Canard or any other thing we want to do to the aircraft. The calculations will tell us how much we need to put in the front seat, or what the limit is etc.

 

In 1968 I was flying wood wing Moonys. Their (and the FAA's) idea of W&B was a stapled sheet showing sample loading. No calcs for W&B. We have come a long way since then, lets use the technology in our communications-----please

 

:::disclaimer:::: Lynn, this monologue was not aimed at you. I know that you know all of this stuff. There are however those on this forum who don't really understand the complexity of W&B and perhaps will make serious mistakes based on a possible misinterpretation of statements.

 

I don't like accidents or failures ::::end of disclaimer::::

Don't really have time for all those numbers and don't remember them all. the aircraft can be set up for a heavy front seat but in a cozy that means that you need a lot of ballast to fly solo. with the seat 10" further back and a front seat max set at 450 lbs. I can also fly it solo at 145lbs without any ballast change. so when i fly to another airport to give a ride to a 305 lbs passenger I do not need to carry the 50 lbs ballast with us like you do in a cozy. it also makes the aircraft sit on all three wheel without falling over backwards when empty. no lifting or power nose strut needed.

Evolultion Eze RG -a two place side by side-200 Knots on 200 HP. A&P / pilot for over 30 years

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at least with 3 inches, which may be plenty for my needs. I realize that the FSW issue is not solved by the widening, only the cabin comfort is. I'll put the person in the back... Or make it a wide 2 seater :-P (Blasphemy right?)

Sounds like you're heading in the right direction... you should download the open-ez plans and give them a good study and get started with this.

Andrew Anunson

I work underground and I play in the sky... no problem

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Lynn:

 

Where do you have some pictures of this beautiful airplane you have built since I left Chino almost 17 years ago? Post some pictures so we can drool over them. STeve

Here are some pics of my Co-Pilot enjoying the conversation that the pilot is having with other pilots. As you can see the subject of the conversation was airplanes and apparently a bit to long also.

Picture_0432.pdf

2005_0713Image0020.pdf

Evolultion Eze RG -a two place side by side-200 Knots on 200 HP. A&P / pilot for over 30 years

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