hank01

This thread was started in the Scratch Building, Aircraft Design, 3D/CAD forum but after taking a cruise through the YMF thread it looks like this forum is a better place for it. To summarize, I have decided to replicate the WACO ZGC-7 in 1/7 scale. It's going to be electric and is my first total scratch build starting with just a 3 view. Here is a pic of it:

The 3 view was drawn up using a very poor copy of an original C7 3 view and every picture I could find on the net. It is attached below as a .pdf file. It's a big drawing and will open in full screen mode when opened. Just hit the escape key to go to a normal screen view mode. Have a look at it and let me know if you see anything out of place.

Hank

jfuller

My Feedback: (8)

Hi Hank,

What a beautiful subject. I admire your courage. I have been modeling aircraft for 60 years but still wouldn't even try this.

Good luck and keep us posted.

James Fuller

hank01

Thanks James! Hopefully I can tap into the vast body of knowledge here to make this happen?

TomCrump

Check out this build: http://www.rcscalebuilder.com/forum/...?TID=8059&PN=2

It's a model similar to what you have planned.

hank01

I checked out the thread Tom. Thanks for the link! There is some good information there. The builder has done a great job pulling the kit together, fine attention to detail. He is building a KS series or standard cabin version. The most distinguishable difference between the standard and custom version is the wings. The bottom wing of the standard cabin is the same length as the top wing and is fitted with ailerons. The bottom wing of the custom cabin is shorter than the top wing and does not have ailerons. There are other differences too but the wings are a dead giveaway as to which version it is. These are beautiful airplanes no matter which version. I been eyeballing the IC series (another standard cabin version) as a possible next project. That's a pic of one below.

The plans for this project is progressing slowly. Found several major mistakes in the frame and former layout so it's back to the drawing board for that. The tail section is in the final draft phase. A reduced copy of it is attached as a .pdf file below. It is labeled as a draft copy and will remain so until the model is built. If the drawing checks out then it will be upgraded to the first revision level and issued full size.

hank01

Got the bugs worked out of the framing and former layout. Had a helluva time getting the fuse form worked out at the transition from fully round to rectangular just below the windscreen and just ahead of the cockpit. There's a couple raised panels there that was throwing me. As it turned out, I was making it more complicated than it really is. The stringer placement is pretty accurate going by some of the pics on file. There is a couple minor deviations but, for a first attempt, it's looking pretty good imho.

The .pdf attachment is a greatly reduced copy of the framing & former drawing. The two pics are of Eric Zimmerman's EGC-7 undergoing restoration.

Ken Kehlet

My Feedback: (89)

Hi,

I own the Harold Osborne Plans and Scale Drawings. I have the Last and Cleanest WACO SRE Cabin Biplane in EXACT 1 1/2 SCALE Plans, 52" wingspan, 688 sq. in. Area, .40-.61 Engine.

Also have a 72" wing larger version WACO plus many other Unique Scale Plans and Drawings.

Send me a PM or E-Mail if you would like a listing of the Plans that I own.

Ken

hank01

The plan is almost finished, managed to get everything on 4 huge sheets. I'm going to have a look at a real C7 this weekend. It's being restored and is one of six C7s currently known to exist. We really got lucky on this one as the airframe is a ZGC-7, the same type that is being modeled. There was a total of 38 C7s built in 1937. A rare bird indeed.

The one I'm going to look at is in various stages of disassembly and repair which provides an excellent opportunity to take detailed measurements and plenty of pictures. No doubt some of the drawings will change after examining a real one but we are well on the way to build a super detailed replica.

hank01

Found some more good stuff. According to the LRDG website, two WACO cabin models were employed by LRDG Air Force during WW2. One of them was a ZGC-7, the other a YKC. The Long Range Desert Group was an elite unit of the British Army during WWII deployed in Africa. [link=http://blindkat.hegewisch.net/lrdg/lrdgaf.html]Check out their website[/link]. Note, however, that the airplane pictured at the top of the page is incorrectly identified as the ZGC-7. Pictured is the YKC.

hank01

Went to check out the C-7 Saturday. Met the ship's owner and chatted with him for several hours. He knows his C-7 through and through and was willing and eager to share that knowledge. Snapped a couple hundred pictures, took 5 pages of notes with sketches and dimensions and was allowed to borrow a copy of a factory original 1/4 scale drawing. What does this do for the project? It changes just about everything. Hindsight says that this newly acquired information applied sooner is better than later but later is better than not all.

Checking the 3 view against the factory drawing shows several major discrepancies. Some aspects are off scale by as much as 10". How bad is that? So, if you saved a copy of the previous 3 view, please get rid of it. It's garbage! We'll get a corrected 3 view posted as soon as it's available.

Avaiojet

I was going to tell you not to have confidence in those 3-view drawings.

I'm glad you discovered this on your own.

The Smithsonian, could also have info on that aircraft. Wouldn't hurt to give them a try also.

But based on your progress so far, you may have all you need.

Great aircraft to model!

Charles

hank01

Charles, you are spot on. Some of the WACO 3 view drawings circulating on the net must be for reference only, drawings that one would see in sales literature etc. Trying to build an accurate replica from one, at least the one I have, is impossible. A lesson well learned! The Smithsonian does hold the records of the company. The data base can be searched using the [link=http://siris-archives.si.edu/ipac20/ipac.jsp?uri=full=3100001~!226604!0&term=#focus]SIRIS search page[/link]. Luckily I won't have to do that. The 1/4 scale drawing on loan has all the info one could hope for plus more.

Avaiojet

Hank,

It takes no more work to build a scale model correct than it does to build one incorrect.

The important issue with any scale model is the correct outlines. Now you have great drawings for that. Detailing can always be added.

You're off to a good start!

Charles

hank01

Thanks Charles. I agree that it takes no more time to build 'em right. Sometimes it takes more time to build 'em wrong. As for outlines, the 3 view first posted looked good comparing it to pictures of full size C-7s. After seeing one close up and having a look at the factory drawings the errors drawn into the 3 view jumped off of the page. But, it's all straightened out now. Attached below is a precise WACO ZGC-7 3-view. Now we're off to work on the plan!

skylarkmk1

Hank,

A word of caution on the factory drawings. They can also be in error. Hopefully you checked them against the C-7 while you were there. The factory guys, drafting a drawing after the fact did not always verify measurements against what was actually built that was modified by the builders to fit correctly (original drawings had an error), changed to speed construction or to install different equipment than originally specified.

hank01

Thanks for the heads up John. Did find several inconsistencies in the factory drawings. The fuselage profile as drawn by WACO does not match the actual profile of the C-7. Also, the top and bottom wing chord as drawn by WACO is too short. The top wing chord is 72" but drawn as 60 3/4" by WACO, bottom wing chord is 48" but drawn as 41" and there are some other items that 'just ain't quite right' with the drawings. How lucky can one be to have a prime, full size subject at hand to refer to?

hank01

We're ready to start building! Went over the drawings completed so far, made a few changes here and there and upped the scale to 1/6. Hoping to get started on the frame tomorrow. The new frame drawing (reduced) is attached below. Yup, I'm excited!

hank01

Got the frame sides built. Found two small errors in the plan drawing, a couple joints are drawn going the wrong direction. It's not a show stopper so on we go! The nose section is next.

hank01

Here is the framework so far, weighs 2.3 oz as it sits in the pics. Time to start work on the cabin interior.

Avaiojet

Hank,

Glad to see you started.

What material are you using for your gussets? Looks like glass cloth?

Charles

georgewaldrop

My Feedback: (28)

Cool build, looking forward to further developments. Are you planning on posting the rest of the plans as you develop them? I am pleased to see you have increased the size to 1/6th scale on the last set of fuse drawings. Is this the scale you are building yours (first post mentioned 1/7th scale)? What power system are you contemplating for this model (understand it will be electric from your earlier posts)? I'll be "lurking" and following along...great thread! [8D]

hank01

No, not glass cloth Charles- it's cotton filled medium weight bond paper tacked down with Titebond 3. I have had great success with this system. It's durable and very easy to work with.

Thanks George! We'll more than likely keep adding drawings as things progress. This build is 1/6 scale. As for power, it is electric and if the weight is kept within the target then an Atlas .40 is the motor of choice.

Avaiojet

Plan ahead for your cabin window glass treatment.

Charles

hank01

Good point Charles. The windows are a little tricky. We have two possibilities on the board- one is to install the cabin windows with the interior, the other is to install the windows after the stringers are placed. Both have pros & cons. I have a feeling it will come down to a combination of both possibilities to keep it simple. I like simple!

Hank

Avaiojet

Real airplanes windows are layered between the aluminum or wood frames.

I personally would "recess" the area where the clear plastic sits. Allowing for the flush fit of the outside layer of framing. Scale size screws can be easily had. A bit of work, but this would allow for removal if repairs were needed.

Charles