building sequence - wings first?

[jpolenek]

Hi all!

In terms of the way the Cozy MKIV is supposed to be built, is there any reason why I couldn't build wings first, then do the fuselage and everything else?

I'm considering some modifications to the fuselage and it will take some time to make the decisions, figure it all out, design it in CAD, etc. But I don't want that to slow down the overall project, so I want to work on the wings in the meantime. I already have some glassing experience from my previous project, so proficiency shouldn't be an issue. Just want to make sure there isn't some technical reason why I shouldn't be building out of sequence.

 

Joe

[Steve Innova]

I built the fuselage first, but then didn't like it and redesigned and rebuilt it.

 

In retrospect, I wish I'd spent the 500 hrs it took me to build the first fuselage on the wings...

[jpolenek]

I built the fuselage first, but then didn't like it and redesigned and rebuilt it.

 

In retrospect, I wish I'd spent the 500 hrs it took me to build the first fuselage on the wings...

That's exactly what I'm hoping to avoid.

[TMann]

I started with chapter 4 to get some experience on some of the smaller parts first. If you do 4,5 & 6, you can make a lot of progress and get that feeling that you have accomplished something. Then move on to the wings, spar, canard........

[argoldman]

Hi all!

In terms of the way the Cozy MKIV is supposed to be built, is there any reason why I couldn't build wings first, then do the fuselage and everything else?

I'm considering some modifications to the fuselage and it will take some time to make the decisions, figure it all out, design it in CAD, etc. But I don't want that to slow down the overall project, so I want to work on the wings in the meantime. I already have some glassing experience from my previous project, so proficiency shouldn't be an issue. Just want to make sure there isn't some technical reason why I shouldn't be building out of sequence.

 

Joe

Joe,

 

The skills needed to properly build a composite aircraft are not difficult in themselves. However, like any skill, they are not a natural part of our existence and must be learned. there are many things that you will learn by doing the glassing, many mistakes, many OH SHI*S (for those faint of ear). So much better to do them on the bulkheads, seat back and easily done lay ups which have a relatively low cost of redoing, or are not as critical with respect to excellent lay ups as are the wings, nor do you have any huge time investment in those individual pieces as you would have in the wing.

In short, start with the simple bulkheads and work yourself up to the more complex structure. Ultimately, doing it this way, you will save yourself a great amount of time and $$. The plans are generally written to expand your skills as you go forward.

 

Now, if you have a lot of glass aircraft building experience, start anywhere you want. Read the plans carefully to determine if a piece that you intend to build must be custom shaped to another piece before glassing.

 

Good luck with your project.

[Waiter]

The wings require more precise workmanship and skills. These skills are developed by screwing up , er, ah, practicing on less precise components first.

 

If you already have the skills, go for it. If not, I would recommend sticking with the plans.

 

Waiter

[jpolenek]

So it doesn't sound like there are any specific roadblocks that should prevent me from building the wings first, except proficiency. On the previous project I worked on, the Dragonfly, the plans have you start with the fuselage sides and bottom, but you can't assemble them until you build the wing because it is needed to perform a critical alignment for the fuselage assembly. It seems like the Cozy4 is similar in that the wings can be completed without needing to have anything else done first.

As far as proficiency goes, I did complete the Dragonfly bulkheads, sides, bottom, turtledecks, and a wing. Given the apparent similarity of construction, I'm thinking I should be ok jumping into the wing build on the Cozy4. My only concern at this point is if I go with MGS epoxy, since it might behave differently (viscosity, wet-out, pot life, etc.) than the Aeropoxy that I have gotten so used to.

 

Joe

[Jon Matcho]

As far as proficiency goes, I did complete the Dragonfly bulkheads, sides, bottom, turtledecks, and a wing.

Considering that, you should definitely be proficient with doing wet layups by now. Jumping into the wings may not be such a bad thing. The only reason I can think of NOT to is that they're so BIG. See about doing the winglets first.

 

My only concern at this point is if I go with MGS epoxy, since it might behave differently (viscosity, wet-out, pot life, etc.) than the Aeropoxy that I have gotten so used to.

Why not stick w/Aeropoxy? MGS may wet out a bit better, and have less odor, and may have a higher Tg, but if you're comfortable with Aeropoxy then use it. Aeropoxy was recommended to me recently by a Long-EZ builder/flyer. Also, MGS is more expensive.

 

Good luck!

[argoldman]

So it doesn't sound like there are any specific roadblocks that should prevent me from building the wings first, except proficiency. On the previous project I worked on, the Dragonfly, the plans have you start with the fuselage sides and bottom, but you can't assemble them until you build the wing because it is needed to perform a critical alignment for the fuselage assembly. It seems like the Cozy4 is similar in that the wings can be completed without needing to have anything else done first.

As far as proficiency goes, I did complete the Dragonfly bulkheads, sides, bottom, turtledecks, and a wing. Given the apparent similarity of construction, I'm thinking I should be ok jumping into the wing build on the Cozy4. My only concern at this point is if I go with MGS epoxy, since it might behave differently (viscosity, wet-out, pot life, etc.) than the Aeropoxy that I have gotten so used to.

 

Joe

 

Joe,

 

Your experience with the dragonfly will serve you well. In that case start anywhere you want to.

 

One thing I would suggest is to do some of the bulkheads and get used to the handling properties of the MGS.

 

You will love the way it wets out. HOWEVER, because you have the ability to control the setting speed by adjusting the ratios of the hardeners, best to learn the ratios that you need to do various types of layups.

 

I use only a fifty-fifty mix (of fast to slow hardener), and it has served me well (after a short learning curve). I have to admit that I chickened out and had Dennis Oelmann build my wings. I want to be young enough to fly the beast when I finish it. However the 50/50 mix would set way to quickly for that procedure.

 

From my memory, the aeropoxy has a relatively long pot life. at 50/50 the pot life seems to be, in 70 degree temps, about 20 min (you must work fast) In higher temps, even less. Much of this has to do with the bulk of epoxy in the pot, as if you do layups on a table (with plastic, such as tapes, etc) once wet out, they can sit and be supple for an hour or so (again dependent on ambient temp.)

 

There is one main difference between the Cozy wing and the Dragonfly wing and that is the spar caps. The d-fly caps used carbon tows, relatively easily wet out while the cozy uses what appear to be fiberglass ropes. Having used them in other applications on the plane, they are harder to wet out than were the carbon caps so factor that into your timing. I found that the ease of wet-out of the MGS to much more than compromise for the downside.

[TMann]

.....yeah .....what he said, and the MGS doesn't stink!

 

T Mann

[jpolenek]

Thanks for the helpful feedback!

 

Joe