Zenith STOL CH 750 - Page 12 - RC Groups
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Feb 26, 2012, 06:45 AM
I don't want to "Switch Now"
pmackenzie's Avatar
FWIW, on the original one the dihedral was set just enough so that the wings didn't look like they had anhedral.
Flat would have worked due to the high position, but looks funny.
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May 26, 2012, 05:32 PM
Registered User
Hi all.
Anyone knows if the project has some update?
May 27, 2012, 04:49 PM
MAAC 15256
Jim 15256's Avatar

Zenith STOL CH 750

Originally Posted by capdrix
Hi all.
Anyone knows if the project has some update?
I'd like to see plans for something like this.
Jun 01, 2012, 10:02 AM
Registered User

New build getting started

If anyone is still watching this thread, I'm starting a build and have some questions:

Where did you locate the CG on your build? I decided on a 38" ws bluecor method that I'm just getting started with. Going to do the slats and offset flaperons using balsa, sanded as needed.

Servos in wings and fuse for tail-feathers.

Saw some comments about being to light for any wind, makes me wonder if I should consider doubling up the foam layers on the front portion of the fuse along with light ply to help distribute the landing gear loads.

Attached are my plans for the 38" ws layout.

Jul 12, 2015, 10:30 PM
thulizulu's Avatar
for those who are still interested in the CH 801, I designed a plane a few months ago. The plane is presented here:
Aug 08, 2016, 01:36 PM
Aeronautical Eng'g Student

Thanks a lot again and for the last time Sir if you may

Sir Bob,

I could not thank you enough for really helping me a little while earlier. I just want to share that I just made my own 3D model of a propeller that i can just attach to the 3D model of the CH 750 you gave. However it took me some time to do all things needed. I chose an airfoil and constructed it for use for the propeller and such, but anyway I managed to do it, yay! (attached some photos of my propeller and my CH 750 3 views )

But Sir, I'm having a hard time lofting the CH 750 on the wings and on some its other parts I'm afraid I may have to ask you again. I am not too keen yet in using lofts on this too many details in 3D modelling for the most part the system says invalid cross sectional every time I loft. I so stressed I can't figure it out ;( For the last time sir if you may, just like what you did, may I just ask for the fully rendered/realistic one you made? I may have asked so much already but I promise that I will catch up on learning so that this would be avoided. I'm very sorry to ask you again sir since I'm a newbie who has got not enough time for the term *cries* If it will be alright, for the same file format and email again? huhuhu

Thank you so much again! God bless!

Aug 08, 2016, 02:09 PM
Retired CAD guy
birdofplay's Avatar
Try passing a plane thru the area that you want a cross section of.
Then chain/link that together and you should have a valid cross section for further use.

Just a thought,
as the ACAD version that you mentioned was NOT available in my CADs' export dialog.

Send me a lost of what YOU can import .. like .skp, or 3dm, 3ds, stl, iges etc
Aug 08, 2016, 02:23 PM
Aeronautical Eng'g Student
I'll try again Sir Bob until I can do it. Maybe I just have to take a nap since I'm like 24 hours out of bed again. I'll also try to ask for some help on my other friends if they can manage too. Thank you again! I hope someday when I got all the experience, I'll do all the hobbies you share. Maybe in 2050 or so but anyways I'm sure to come visit here again hehe
Aug 08, 2016, 02:33 PM
Aeronautical Eng'g Student
I can save the file as .dwg, .dws, .dwt, and .dxf file formats. I also searched that I can save solidworks formats to ACAD .dwg. Also there's free Online 3D Converter which I think may prove useful? Never tried one before since my school only has AutoCAD, SolidWorks, and Inventor. But I only use ACAD and pass my files in .dwg formats
Aug 08, 2016, 05:13 PM
Retired CAD guy
birdofplay's Avatar
check your e-mail for a parasolid as Solidworks
Aug 09, 2016, 08:34 AM
Aeronautical Eng'g Student
okay Sir Bob. Just a moment.. Will be right back
Aug 10, 2016, 11:16 AM
Aeronautical Eng'g Student

Despite some progress, still of little to no avail ;(

Originally Posted by birdofplay
check your e-mail for a parasolid as Solidworks
Sir Bob,

I have finally imported the parasolid file (.x_T) to a .dwg file format via Inventor 2017. However, I tried constructing/putting together the parts via all the commands i know and tried to practice. I can't form the a/c cowling properly and the most of the lofting (whether via guide, path, join edges or cross section loft) says

Selected cross section is not a valid type.
The selected entities are not valid.
Modeling Operation Error:
Some but not all sections meet.
The selected entities are not valid.
Cross-section curves must be all open or all closed
Not a valid path/guide etc. even if I have made sure the highlighted objects are okay (I also watched lofting tutorials on youtube)

"Cannot sweep or extrude a self-intersecting curve"
Also sometimes polyline, 3D object can't be joined and the like.

And when I try to join a closed shape for a cross section it always says: "0 objects joined, # objects discarded from the operation"
I can't join/unite and loft them regardless of how many times I try to highlight them and type the command

I even experimented/tried different things like from different parts and smooth to ruled options but still to no use.

Anyway, I also redid the 3 views for accuracy to use for another activity, where I'm having a scaling problem because I traced the front view and side view but when projected, the height with the landing gear does not meet with the other. (attached a pdf file so you could see if you want) also if I scale to meet the same height, the length changes consequently

Omy I'm at a newbie level 1. Worst feeling ever. I kept trying but I guess I should really seek some help for tomorrow.

I'd bring my laptop to school and see if my friend could do something about it. I tried doing it the whole day but no progress. It's very frustrating ;(

I still have until friday (or if gets moved, until tuesday), just like most of my other subject's deadlines omy I'm dead. I can't learn and grasp 3D CAD in just a few days until my deadline huhu. I have watched 3D tutorials but am still not advanced. My only real achievement is my 3D propeller activity (which of course had some help with my also busy good friend)

At this point I'm at no idea to what I'm going to do on the 3D modelling, maybe I should focus more on what I can pass so as not to pile up my requirements again. Sad sad sad

Thank you again Sir Bob for the help. The file should give me some output and If at some point I manage to finish the work, I'll just share it here Thank you again! <3 ^_^
Aug 10, 2016, 12:06 PM
Retired CAD guy
birdofplay's Avatar
Sorry to hear that your CAD, Solid Works, is not happy with my files.

When I make the Section lines I use nothing exotic.
Unless you consider Chained Lines and arcs exotic.
I can't specifically recall but I suppose some could be B-splines

Occasionally I get a complaint about self intersecting lines but my CAD seems to
still work them and get past it.

You could get rid of all the lines and acrs or just put them on another level
then pass planes thru the surfaces that I exported and recreate you own sections.

Check direction too as I helps to have everything going the same way especially if you are
doing Lofting of surfaces.
Jan 12, 2018, 01:48 PM
Watch this!
mpikas's Avatar
So did the 60" ever fly? Was the 119" ever built? Any others?

Those of you trying to build these things are you sticking with the stock airfoil profile or doing something more "reasonable?" (it just seems like this thing is super thick for its length and I haven't been able to find any actual profiles by its airfoil number, naca650-18 (I wonder if 18 is 18%, not sure if the modded is part of the number)
Jan 12, 2018, 02:45 PM
Retired CAD guy
birdofplay's Avatar

As fo my model ...

It was eaten by mice in a shed and I just tossed the whole attempt.

A shame to be sure but C 'est la vie !

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