Introduction

[Carl P. Lindon]

Just a quick note of introduction. Whilst not a pilot I am interested in flying and even more so in the homebuilt aircraft building process. (Yes I am an engineer both a work and in many of my personal pursuits!)

Recently I have begun investigating the homebuilt options and my thoughts seem to be converging on a 4/5 seat canard configuration, the most popular of which seem to be the Velocity line of kits and the Cozy MkIV. (I did briefly "flirt" with the idea of a Rutan Defiant until I found out that even with 2 engines it cruises slower than the Cozy so, as promising as I thought that option might be, it was summarily rejected.) Being at best a "newbie" I have many questions and am hoping that this forum can be of assistance in both the research, airframe selection, options/modifications evaluation and building processes.

Questions will be forthcoming but any general comments on the relative merits of a Cozy versus the Velocity XL line would be much appreciated.

 

Thanks and Cheers

Good Flying

 

Carl

[PaulL]

I have an SQ2000, similar to Velocity and I really appreciate the gull wing doors so you don't have to climb up like in a Cozy or EZ. And the Velocity XL will have bigger payload amd more pilot/passenger - for Cozy IV it is about 410lb and its "cozy". Of course you will probably find the Velocity more expensive to build and somewhat more thirsty. There's a CAFE flight report for Cozy IV at:

http://members.eaa.org/home/flight_reports/cozy_markiv.html

 

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Paul Lee, SQ2000 canard: http://www.abri.com/sq2000

[Jon Matcho]

Carl, we have similar backgrounds and interests. I was first looking at a Velocity, but decided on a Cozy based on price and performance. The small Velocity aircraft are similar in size and performance to a Cozy, but I believe the trend has been for them to become quite large, especially with the XL and XL-5 models.

 

I chose to build a Cozy IV with AeroCanard FG adjustments, which makes for a slightly wider rear. Others have widened the front a couple inches as well. I know of the 'King Kozy' which attempted to be the biggest Cozy modification, but was never finished. I met a fellow at Sun-n-Fun who was increasing dimensions of the entire plane by 15%. Several have raised their canopies, as well as increased the room within the bubble.

 

As long as you choose a canard, you're making the right decision, and are welcome to discuss here. I've just started the journey myself.

[Len Evansic]

I met a fellow at Sun-n-Fun who was increasing dimensions of the entire plane by 15%. Several have raised their canopies, as well as increased the room within the bubble.

Was the guy with the 15% scale-up successful? I mean, has he completed his plane and flown it yet, and if so did he have any adverse problems?

 

By any chance does he have a web site?

 

-- Len

[Carl P. Lindon]

Was the guy with the 15% scale-up successful? I mean, has he completed his plane and flown it yet, and if so did he have any adverse problems?

 

Les Orosz is the one working on the 15% scale-up . I talked with him a few weeks ago and he has his fuselage tub together now but it is still early days for him. He advised me that there are a number of dimesions that don't scale-up by 15% such as material thicknesses which affects the locations of some components and other dimensions that you don't necessarily want to have scaled-up without some "rationalization" (eg dashboard bottom edge doesn't need to be scaled and as such can allow for a larger leg opening, rudder pedal positioning etc).

 

I'm still reviewing the options but hope to buy the plans relatively soon and begin the "rationalization process". There are still a large number of variables though such as actual empty weight and operational CG range. Some of these though will simply have to wait until one is completed and tested .

 

Kind of funny though, for all the maligning I received when I posted a question about the 15% scale-up on the Cozy_Builder's list I have received a number of private replies that have been very supportive and technically educational as well as one from another prospective builder interested in the same enlargement!

 

Cheers

Good Building and Flying

Carl

[Neverquit]

Welcome!

 

You'll open a can of worms with that question. What is known for sure is probably something you already know. The Velocity is more convenient (auto-like) in it's design and luxury although the trade off is expense. It generally costs more to build because it can be purchased as a kit unlike the Cozy MKIV. The Aerocanard is more or less the "kit" version of the Cozy but again the cost for convenience and a faster build is there. As far a performance goes you have data that shows both planes with similar characteristics if provided with similar powerplants etc. Both builder/flyers are loyal to their designs. One Cozy flyer at Oshkosh told me the Velocity is a flying crowbar. I have a friend here building a Velocity that says I'm building a bathtub with wings (or had a friend ) and it goes on and on. I certainly wouldn't trade either one for a "soup can" plane.

 

My opinion is if you want to say "I built it" with a huge grin and want to enjoy the whole experience (including personal mods - try the cozygirrls website) from the beginning then go with the Cozy. I might be biased here though.

 

Neverquit

[Len Evansic]

I'm still in my gathering information stage on this project, and I don't aim to be as ambitious as a 15% scale-up. Nonetheless, I am interested in a less cozy interior. What I'm curious about is how the general enlargement will affect the flying of the plane.

 

I mean, from what I understand, the Cozy III and IV have the same wings as the Long-EZ. Both of them have widened the fuselage, but neither has changed the wing planform and airfoils, save the shortening of the canard and the update to the Roncz airfoil on the canard. If the wing dimensions are scaled up, how are the aerodynamics affected? Nat didn't change dimensions with the fuselage enlargement, and the plane flies just fine.

 

Would it make more sense to enlarge all of the fuselage measurements by 10%, and only increase the wing dimensions by 5%, only in the lengthwise direction, taking the difference of the fuselage up in the strakes. I suggest this by imagining a Cozy scaled up to the size of the Beech Starship, or a 727. A scaled up Cozy would look like a Fisher-Price plane with extremely thick wings.

 

Also, the fuselage houses mostly air, which isn't that dense, but the wings house fuel, which is. I know that you could just use less of the wing volume for fuel storage, but it seems that enlarging the fuselage has less of a detriment to wing loading.

 

-- Len

[Jon Matcho]

Welcome one and all!

 

Was the guy with the 15% scale-up successful? I mean, has he completed his plane and flown it yet

He hadn't finished his plane yet, and only had bulkheads and fuselage sides happening as far as I could tell.

 

By any chance does he have a web site?

Sorry, no. I did manage to contact him again, and he recommended NOT to pursue this route as the design changes are overwhelming. I would agree. If you want a slightly "less Cozy" interior, you could consider widening the rear and even the seatback by just a couple inches. The consensus seems to be that anything beyond this will require calling in the aerodynamicists.

 

Get yourself a set of AeroCanard plans to see where to begin with this. You could also google 'King Kozy' and get the dead-end story of an ambitious enlargement project.

[Wayne Hicks]

There is a former builder/flyer in California who took a standard plans- built fuselage, split it down the middle from nose to tail, and widened the entire fuselage by 6 inches. (I'm not kidding. He really did slice the thing down the middle and scarfed in 6 more inches.) He moved the front seatback aft by 1-2 inches. He raised the turtleback by 2 inches.

 

He left the flying surfaces alone except for cutting the canard's center section core 6 inches wider and making the center section spar 6 inches wider.

 

By all accounts it looked like a Cozy (only the astute observer could tell the difference) and it flew like a Cozy.

[Len Evansic]

There is a former builder/flyer in California who took a standard plans- built fuselage, split it down the middle from nose to tail, and widened the entire fuselage by 6 inches ...

... By all accounts it looked like a Cozy (only the astute observer could tell the difference) and it flew like a Cozy.

Did he put up anything on any websites, or does this predate the web? The log of that project would be a very interesting read. I saw other threads were a 3" widening was discussed (and argued), and this after-the-build widening should bode well for them.

 

I'm still in the info gathering stage, but so far I've been advised to leave the wings alone, and at most widen an inch and elevate the turtledeck by an inch. Wow, a bisection and 6" insertion of materials just boggles my mind. I'm pretty sure that everybody he discussed this with, must have told him that he was crazy. This is something that couldn't (more appropriately shouldn't) be done, but the assertion that it it flew like a Cozy does inspire me.

 

-- Len

[Wayne Hicks]

I guess what I'm trying to say is engineering a bigger Cozy may not necessarily mean scaling up every piece of the plane. The Long EZ and the Cozy generations share virtually identical wing planforms. (Caution: The Cozy IV spars are thicker to handle the higher weight.) That leads me to think that the planform is robust.

 

One can make a legitimate stretch (get the pun?) that the fuselage geometry can be altered widely (get that pun too?) without affecting the flight characteristics greatly.

 

I say this with great caution because I suggest there will be a point at which fuselage width and height DOES start to GREATLY affect flight characteristics. I personally do not know where that is.

 

In this case, this former builder/flyer effectively scaled up the fuselage by 15% (42 inch width to 48 inches) without scaling up the flight surfaces. Goal achieved!

 

This builder/flyer did not have any website and did not publish any bread crumbs to follow. I think it's good advice to leave the wings alone unless you or a friend have the technical know-how to do the analyses. This person had long conversations with Nat, but Nat of course would not approve of his mods nor give him any further building advice.

 

Just know that when changes are discussed, there will always be those that say the world will come to an end. The only truth is your world might come to an end if you change too many things. But then again, you could create a new, very popular design based off others. Nat did this. Steve Wright did it with his Stagger-EZ. There are just too many "experts" out there who are nothing more than just quick on the draw with their opinions. It's up to you to figure out who's who.