Zenith STOL CH 750 - Page 4 - RC Groups
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Nov 18, 2010, 01:22 AM
Yes, "that" Karl...
karl k's Avatar
Are you staying scale with the airfoil on the stab as well?

I was actually thinking of removing the tail 6-12" back from the trailing edge of the wing.
I've got a short box truck, so hauling a plane nearly 10ft long may prove troublesome.
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Nov 18, 2010, 10:31 AM
Retired CAD guy
birdofplay's Avatar
Ya know I never considered an airfoil change. Hmmm
Since it's going to be so light I 'm hoping that it will work.

the H-stab on the 60" version is sorta similar.
AKA - close enough by hand sanding.

Re the Fuse width. I measured in CAD and it's Supposed to be 7.56" wide at this size.
But after assemble it seem to have grown a tad. to ~7.875 - Under 8" !
I will make that change in the drawings as well.
I went back and took a closer look at the Fuse width concern.
I see what happened. The drawings are a bit askew. As I have found MOST drawings are.
I measured the Front view at 7.5 " but the Top View is drawn slightly non-symmetrical.
So, after placing a center line and drawing the Right half I just Mirrored it to get the left half.
BUT I didn't notice the slight Growth due to the offset Center line.
I'm NOT Going to any beauty contests wit this bird nor any scale competitions.
Still I'll fix the drawings an narrow it up a smidge.
It's only "off" by ~ .25 " in width. Close enough for a 3 day design.

As I removed the tape while waiting for the PC to boot this AM I thought
I SHOULD have made the Vert Fin and the H-stab a SLOTed Fit to KEY them together.
Oh well another minor drawing improvement.

I suppose you COULD Split the Fuse at the Tail Cone, right behind the TE.
Lots of "MEAT" there to mount attachment bolts and ply reinforcement.
I suppose it could even be a Keyed with tabs and slots too.

At 1/3 scale I get 7.27 ' long

You gotta upgrade to a Big truck with an 8' bed ! :-)
Last edited by birdofplay; Nov 18, 2010 at 10:51 AM.
Nov 18, 2010, 11:40 AM
Yes, "that" Karl...
karl k's Avatar
It's not a tiny truck...
Nov 18, 2010, 03:08 PM
Retired CAD guy
birdofplay's Avatar
OK, I'll see your Big Truck and RAISE you a Crew Cab, 8' bed and a CAP !

But forget parking this thing in Town and a garage ! :-(

Nothing wrong with RAM's , My son works at Cummins in Indiana.

Under the CAP are TWO carpeted slide out Trays 4' x 8'.

Foamys on the bottom and Aero Tow sized stuff on the top !

If I keep adding to my model collection I'm going to need a trailer next.
Nov 18, 2010, 03:36 PM
Yes, "that" Karl...
karl k's Avatar
I didn't say it was big, just not small

You get the choice of more cab or more box with the 1500. I chose more cab.
Nov 18, 2010, 03:57 PM
Luis Claudio - Rio - Brazil
Luis_Claudio's Avatar
Nov 18, 2010, 05:21 PM
Retired CAD guy
birdofplay's Avatar
I used to have a 5th wheel so I needed the 250 sized truck.
Not so much any more, but hey, I have lots of model transport room.
I was NOT back into modeling when I bought the danged thing in 02.
I'd been away from models for about 12 yrs.
Then I went to the Toledo 50 anniversary show and saw all the NEW stuff !
the rest it history .

Today I've managed to get myself into a BIND.

While Sculpting in the Cowl area I realized that
I have NOT allowed for ACCESS into the Cowl for Motor mounting etc !

I was so focused on getting the 3D to look nice that I didnt think about
how to actualy USE it !

Kinda like the engineers that put the spark plugs OUT OF REACH !

Anyway, I'm thinking that I'll just cut the bottom as a flap type hatch.
Pix l8r this PM
Nov 18, 2010, 07:57 PM
Registered User
biznak's Avatar
happens all the time where i work too, actually my current foamy build is in a similar state...i'm thinking of a hatch too
Nov 18, 2010, 11:30 PM
Retired CAD guy
birdofplay's Avatar
Well I've spent most of the day fooling around with this Cowl.
Lots of fitting and bending and gluing and taping it down.

The last piece is setting up as I type !

Tomorrow is a lost day as "WE" are going shopping !

SO Saturday is Tackle the Wing day !

I'm thinking that we're gonna need working struts for more that just scale look.

The Top Cabin edge is flimsy even with my 1/32" ply.
I'll carve in some holes mounting plates on the bottom of the wing
at the third rib.

Wire LG is looking like a fairly good option.

HK STILL has not committed my package to the Mails YET !!!
They are starting to loose their sense of urgency IMHO :-(

Several Build Items kinda depend on some of those parts.

whatchagonnado ?


Last edited by birdofplay; Nov 19, 2010 at 09:21 AM.
Nov 19, 2010, 01:25 PM
Registered User
My Brother-in-Law and I took the Intro build course at the Zenith Factory last Sept. It is a two day course where you put together the V-stab. He is set on building the 750. This is a very impressive little plane, very well suited for the STHOL roll and the home builder. We finished out the V-stab in about 5hrs. The people at Zenith claim and 500hr build for the total airframe.
Your's looks to be a nice tribute BoP.
What type of CNC machine are you using?
(Attached: Trying to figure how to mont the Stab on the back of Subie for the ride home)
Nov 19, 2010, 01:31 PM
Retired CAD guy
birdofplay's Avatar
MJER: I have a Shopbot 4' x 8" steel bed.

Before starting the wings I just ordered 4 bottles of the foaming White Gorilla glue
from Grizzly industrial as I believe they have a much better price than Lowes or else where.

Plus I got a free whatever.

I'll be looking for some of those little Plastic Wire Hold downs.
You know, two screws on a oval lump with a wire slot on the bottom.
They are for mounting the LG wires to the Ply plate that I glued to the bottom.

I have picked out 6mm CF tubes for the wings and cut the 1/4 x 1/4 spars too.
It should go quickly once I get started.

What do you think of using a strip of VELCRO on the top Fuse edge
and the wing root to hold the wings to the fuse ?

The Cf tube will be engaged in a thru hole in the top fuse edge.
As well as a anti rotating CF rod near the TE.

Considering that the Struts will be functional it oughta work, eh ?

The velcro should be Hide-able under the top wing covering at the fuse mating edge.


Nov 20, 2010, 02:54 PM
Retired CAD guy
birdofplay's Avatar
My Suby is a 98 - still going !

Last evening I did one half the wing and I started the Other half this AM.

Then I decided that what I needed was a big rib shaped chunk of Pink foam for the TIPS !
Something to put the Horner Bevel on, ya know.

I've added that detail to the Drawings update list.

See pix

After all is set up and cured I plan to Cover the wings with 3mm depron sheeting.

Wing mods will include a bottom side rear spar as it was more work to keep the ribs Square and parallel without one.
Plus the ribs need a anti rotating pin holes in them. A 1/8 hole should work for a CF rod glue in.

I switched to using yellow PU as it sets up faster with a bit of moisture.

Edit in some pix of yesterdays work
Last edited by birdofplay; Nov 21, 2010 at 11:35 AM.
Nov 21, 2010, 11:41 AM
Retired CAD guy
birdofplay's Avatar
To build the wing I used a 2x4 piece of GRANITE as a flat then as a Weight.

To cover the wing I cut a piece of 3mm depron and COVERED it with some
extra thin Laminating film. Then I used a ruler and about a 1/8" dia round ended tool
and Made "strike" lines across the Nose portion of the wing covering on the opposite side.
After that the Depron is gently NUDGED into a bend.
There are lots of threads on bending depron - Pick your favorite.
This is a fairly large radius so it's not that big of a deal.

AND if it turns out a little "facety" just remember that it will be hidden by the SLATS !

In between hunydos I'll try to get the other half covered today.

Then ON to the LG wires so I can get this bird up on it's feet !
Nov 21, 2010, 03:16 PM
Registered User
biznak's Avatar
that is coming along nicely, i still wonder about facing the ribs with 1/16th sheeting and using some iron on film...i suppose you'd have to use bigger spars perhaps though...i just love the way balsa ribs look with opaque covering!!
Nov 21, 2010, 05:42 PM
Retired CAD guy
birdofplay's Avatar
I like the covered Ribs look too.
Like the Old timers Covered in transparent monocote

The lighter this thing is built the less strength it'll need.

The whole fuse is only 8 oz right now.
3.5 oz for the dryed wing
Depending on how the LG and motor mount adn struts turn out
I might ~ 2 lbs maybe 2.5 Lbs .
Pretty light stuff.

I made some all foam wings once a while back - Still using them.
Ailerons and Flaps - two servos on each side.
Regardless, each side would support a Vise in the middle supported at the ends !

I'll see if I can find the previously posted pix.

Here it is - those are 24" sections !
Last edited by birdofplay; Nov 21, 2010 at 05:50 PM.

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