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Steve Innova

Redesigning the Cozy fuselage

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I'm cross posting this from the canardaviation.com forum...

 

As some of you may have noticed, I recently put my Chapt. 4-7 fuselage tub up for sale. It's not because I've abandoned the build, but rather because I've decided to take a different path, both in construction technique and in the desired outcome.

 

My objective is this -- I want to build an entirely new fuselage for the Cozy Mk IV, one that will retain the proven aerodynamic dimensions of the Mk IV while adopting a more streamlined form, and modified for greater ease of entry and visibility. My design will be original and unique, until I publish the CAD rendition and 3-view drawings, you can imagine the shape of the SQ-2000 or the Stagger-EZ to get some idea of what this fuselage will look like.

 

Details:

 

What stays the same:

- All basic MkIV fusage positions (i.e. canard at F-22, etc....) The canard/wing/spar positions remain the same.

- Same weight and balance, cg position

- All bulkheads located at same position, constructed w/same layup schedule (F-0 may move forward).

 

Modfications:

- elongated, sharpened, "shark nose" (see SQ-2000, Stagger-EZ, Diamond Twin Star). Nose is lofted instead of flat, with a smooth curve from tip of nose to the canopy

- 3" wider at front seatback, 2" wider at rear seatback

rounded fuselage bottom

- canopy and turtleback lofted, and wider, extending all the way to side rails

- forward canopy opens rearward (berkut style)

- aft window/door combinination, uses a unique rear opening design - to be revealed later, it's awesome!

- both fore and aft canopies can be jettisoned in-flight

- strakes similar to Cozy Girrrl strakes, but more rounded and smoother, concave transition from fuselage to strake

- shallower fuselage (2-3" removed from bottom), slightly more upright seating (pilot sholder is above side rail)

- composite "hoop" roll-over structure (integerated into rear window/door "T-top")

 

Undecided:

- NACA duct or armpit scoops?

- may use hydrolically actuated trailing link nose gear from the BD-5

- BRS compatability (this may eventually become the standard for all GA). I could route channels for the straps on the outside fuselage, at the seatback and firewall positions. The BRS rocket/chute tube could be attached to the back of the SB brace, with a clean shot out the top of the turtleback. I hear they're designing a version for the velocity--about the right weight I think.

 

 

Construction technique:

I'm busy modelling the new fuselage in 3D using Rhino 3.0. I've imported the Cozy 3D models to get all the original Cozy dimensions, and from there I am adjusting lines and lofting components to get the shape I want, while retaining all the critical dimensions and fuselage positions. I should have a rough model complete by next week, with additional details (doors, canopy, interior center consol, etc...) in by November.

 

The biggest question I have now is how to construct this new fuselage. I could use moldless construction for portions of the fuselage and hotwire the lower corners and bottom. However, I'm leaning towards constructing a full-size solid foam "plug" and pulling female molds from the plug (I'll need to do this for the compound curves of the nose and canopy/turtleback anyway).

 

Although it takes extra effort, this will give me a two-piece fuselage that I can just attach together and add bulkheads. If others are interested, I could also duplicate my work and manufacture addtional molded fuselages. Thoughts???

 

 

In the kit plane world, talk is cheap and lot's of back-of-napkin designs never make it into the air. I have had the small benifit of building a Cozy MkIV fuselage already, and after a year and half, am reasonably well versed in the techniques. This is a big undertaking, so wish me luck!

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Wow, a monster dose of ambition do you have! I like it.

 

I think a fuselage modification is certainly possible, with some adjustments. I'll just throw my $0.02 worth of feedback to you...

 

- 3" wider at front seatback, 2" wider at rear seatback

The AeroCanard modifies the Cozy by 3.5" - 5.0" in the rear (I have to take a real measurement one of these days). Why not do 2" at the front and the same width as the AeroCanard in the back?

 

- aft window/door combinination, uses a unique rear opening design - to be revealed later, it's awesome!

Why hold out? You throw a statement like this in the mix and you have to at least describe what the napkin looks like.

 

- both fore and aft canopies can be jettisoned in-flight

The forward canopy can -- just open it and it will rip right off. Not saying the Berkut design is bad, just that you don't need to do anything special to take advantage of a 100+ MPH wind.

 

I should have a rough model complete by next week...

I would really like to see your mock-up!

 

The biggest question I have now is how to construct this new fuselage. I could use moldless construction for portions of the fuselage and hotwire the lower corners and bottom. However, I'm leaning towards constructing a full-size solid foam "plug" and pulling female molds from the plug (I'll need to do this for the compound curves of the nose and canopy/turtleback anyway).

 

Although it takes extra effort, this will give me a two-piece fuselage that I can just attach together and add bulkheads.

That's what Bulent Aliev did -- check his Web site if you haven't already.

 

If others are interested, I could also duplicate my work and manufacture addtional molded fuselages. Thoughts???

If you're talking about making a mold, that would be a really nice thing to have WHEN you finish and are showing your plane like Steve Wright's. Then the mold would be of greatest value to others. I don't think many would make this leap of faith with you without seeing your napkins. So let's see some napkins! :)

 

The part of the concept that's really good is keeping to the Cozy design, so that you can turn over to per-plans Cozy building for everything else. Do that as much as possible and you definitely would have something of interest to others, IMO.

 

I'm interested. What's next?


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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...Undecided:

- BRS compatibility (this may eventually become the standard for all GA). I could route channels for the straps on the outside fuselage, at the seatback and firewall positions. The BRS rocket/chute tube could be attached to the back of the SB brace, with a clean shot out the top of the turtleback. I hear they're designing a version for the velocity--about the right weight I think...

I still have a lot of doubts about BRS. I think it is an expensive device, in cost, weight, and size, and has not proven itself effective in types of accidents suffered by GA aircraft.

 

The other option is to put the money for BRS (about $12K or more) into to other items/equipment that may provide a better margin of safety. $12K spent on flight instrumenation, power plant reliability, or flight training would probably generate better results.

 

Besides all that, it adds $12K+ to the cost of building your airplane.


Nathan Gifford

Tickfaw, LA USA

Cozy Mk IV Plans Set 1330

Better still --> Now at CH 9

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I still have a lot of doubts about BRS.

Everyone knows the real reason for a BRS in a GA plane is convince the friends and family that it's "safe" to fly with you.

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I usually post at the other canard forum, but it's been some time since I updated this site w/my Cozy redesign plans.

 

I've made quite a bit of progress in modelling the new fuselage as well as researching and identifying the construction technique. I'm using Rhino 3.0 to model the design in 3D. After probably 100-150 hrs of learning the system, sketching out ideas, tweaking, starting over, starting again, etc..., the exterior is finalized, as is the interior.

 

As for construction technique, on some good advice I'm adapting two composit boat-building techniques, the cove-and-bead strip method and the vertical stripping method. The standard Cozy methods won't work for the compound curves of my design, but these adapted boatbuilding techniques will let me easily make compound curves to match the 3D cad model. No mold necessary -- it'll be a one off, though fully replicable thanks to the 3d model.

 

As for materiels, I'm using (mostly) the standard glass layup schedule, with some reinforcements here and there. The main departure is that instead of 3# 3/8" divinicell (H45 foam at Wicks/ACC), I'm using 3.7 #, 1/2" Core-cell SANS foam. I've researched the material properties and find it to be slightly superior to the divinicell. Furthermore, its easier to shape and heat-form, which is essiential w/my construction method.

 

I begin the build on Thursday!

 

Here are some rendered images of the 3d model:

post-529-141090153534_thumb.jpg

post-529-141090153536_thumb.jpg

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This would definitely be an eye-catcher. Looks like Steve Wright's Stagger-EZ to me, but as a 4-place.

 

I would be interested to follow your progress along the way, and look forward to any pictures as you go through the process.

 

Best wishes!


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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Thanks, it's an original design not a copy, but the SQ2000 and the Stagger EZ certainly inspired my ideas. Hopefully I'll be able to beat Steve Wright's 6500 hr build time though :envy:

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Very nice looking. Question, what type of simulator work do folks like you do who make big mods during the design phase? Just wondering if you wait until you hit vRotate to find out if it flies, or if y'all try plugging the numbers into X-Plane or something similar?


Ben Hallert - http://hallert.net/cozy/ - Chapter 1 - EAA Chapter#31

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Very nice looking. Question, what type of simulator work do folks like you do who make big mods during the design phase? Just wondering if you wait until you hit vRotate to find out if it flies, or if y'all try plugging the numbers into X-Plane or something similar?

 

Well, "folks like [me]" aren't that much different than the ordinary builder.

 

I've made some rational decisions to keep the critical airfoil and thrust line relative positions the same. The aerodynamic changes are all to the fuselage, and based on the success of the similar Stagger EZ and SQ2000, I think they are within the overall limits of the design. Deminsions are within 1-3" of the standard MkIV.

 

The first thing I'm building is the lower fuselage, the tub. This isn't very different from the standard tub, just w/more rounded side and lower nose. My main concern is that the larger, rounder canopy/turtleback will act as a more powerful lifting surface. Mitigating this is the fact that most of that lift is close to the design CG... Nevertheless, I plan on conducting some CFD analysis of the upper fuselage surface bofore building it.

 

Finally, I'll use a moveable weight in a large-bore PVC tube stretching from the firewall to F22 (on the passenger side) during flight testing, to allow me to safely determine stall, and CG positions.

 

Basically the answer is I've made the best decisions I can with what I know about the design, plan on doing further analysis, and will have a plan to mitigate risks during flight testing.

 

of the original design specifications (airfoil and thrust line relative positions)

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Steve how is the redesign and building of the modified fusleage comming along?

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Steve decided to sell his project in 2017.  This is all that's left.  ?


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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Steve, I am in the search of a good set (accurate) of .dwg (Autocad or convertible) plans of the Cozy Mk IV, where have you found them?? It has to be digitalized. I pretend to actually build it, so it has to be as accurate as possible. Is there any 3D reliable model also?

I have found a great open EZ one but not a good Cozy...

Thank you very much, best regards

Daniel

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Daniel-

Where did you find the open EZ 3D model?

Jeff

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