Cdallas2

Just a quick update......

Now have almost 40 flights on it. Flying very well.

Have replaced fiberglass gear with a CF set. Will allow me to try some larger props. It's a very fast plane but I would like to trade off some speed for better vertical. Running an 11x7 now but I'd like to try an 12x6 or 12x5.

Next couple days I'm going to start making molds for wheel pants.

Alex7403

It looks great cdallas, to what and how the LG is attached to the plane, how does it reinforced?

Cdallas2

If you look at the picture on post #2 you'll see what I ended up doing.

I replaced the balsa piece with 1/8" aircraft ply. I then added another piece of 1/8" aircraft ply where the gear would be mounted. I then used some balsa tri-stock to beef it up some more.

This is the same way I did it on my US 60 and it's worked very well.

I feel it gives the US's a more modern look and another option if you want to use fixed gear but don't like the looks of the wire gear hanging down.

Cdallas2

Added the wheel pants finally.

Over 60 flights have now been flown.

This is now my favorite plane I've got as it can do pretty much anything I ask of it. Very quick and very stable at low speeds as well. It flies noticeably better than my standard Ultrasports and that's saying quite a bit.

doxilia

My Feedback: (3)

Very interesting approach to the US! I enjoyed your nice build.

If I may make a comment regarding center wing glassing, I like to layup the glass work in decreasing glass weight and increasing width. Depending on the project I will use two or three layers of glass starting with 5-6 oz cloth followed by 2 oz and then 3/4 oz cloth. For smaller projects (40 and under) you can use 5 oz followed by 3/4 or 2 oz followed by 3/4. The nice thing about this approach is that it leaves a very smooth final layer which flows nicely into the wing provided you sand properly between layers.

I also like to lay the glass over the masking tape wetting down the area so that the epoxy doesn't flow randomly beyond the cloth. When the epoxy is half way cured, you then cut lightly (not into your sheeting) along the inner masking seam through the cloth and then lift the masking tape along with some unused cloth leaving a clean line of both cloth and resin. It also allows the cloth to be smoothed out nicely as you spread the epoxy out toward the masking tape where it will be lifted if in excess.

On another note, what software do you guys use/recommend for mocking up trim schemes quickly? I've always done it by hand but software is evidently much more flexible.

David.

prgonzalez

Very nice job in all of your US.

Is there a significant difference in weight among your Ultra Sports?

edmoor

My Feedback: (1)

looks stupid......with that wing......why would you want that anyway?...cant you use the proven design? always puzzles me why anyone thinks they can beat engineering.....

doxilia

My Feedback: (3)

Well,

sometimes because people are aerodynamicists or aeronautical engineers and experimenting is fun!

Personally, I think a forward swept experimental variation on a proven design is a great idea. Apparently it flies quite well!

David.

EscapeFlyer

My Feedback: (1)

Never progress...Never Learn...Never make advancements...Stay completely ignorant...Never improve the quality of life...

...good grief!!!

sticktickler

Actually Cdallas2's aeronautical engineering is quite sound, all be it strange looking the forward swept wing is a very maneuverable and proven wing design. This design tends to pull more air flow towards the fuselage rather than away from it as a standard wing does. Thus the air being pushed back and towards the control surface of the tail moment most likely increases the felt performance control of this model. Airflow from wing tip to wing root on a forward swept wing can prevent a stall of the wing tips and ailerons at high angle of attack making for safer landings during slow flight. This is why canard type aircraft are stable and very maneuverable. At the end of the day one could sure say Cdallas2 did in fact BEAT THE MODELS ORIGINAL ENGINEERING.

Cdallas2

This project is something I've wanted to do for a long time and doing it with a proven design has reduced the amount of unknowns and made great plane (and in my opinion) a better looking and even better performing one.

I can now take what I've learned on this project and put that toward a version built from the ground up in this same configuration. As the design evolves I hope to make it even better. Plans are still in the works for a 90/1.10 sized version and possibly electric. I've also come up with some slightly crazier ideas for a float version (Schneider Cup style) and even a push-pull twin.


My Ultrasport 40 retract version weighs in at 5lb 15oz and the Forward swept version tips the scales at 6lb 1oz. That also includes a few ounces in the nose, the heavy Great Planes adjustable motor mount and a heavy sub-C cell battery. I could reduce that by about 3oz by switching to a lipo alone.

The Ultrasport 60 is 8lb 4.5oz.

When I do mine, I put the outline in Autocad, convert it to a bmp and either play around with it in MS Paint or Photoshop

doxilia

My Feedback: (3)

Thanks for the reply CDallas. I'll probably attempt something in Illustrator.

David.

sticktickler

Good choice doxilia Adobe Illustrator is a great design tool as it draws in Vector as apposed to Raster. Raster (Photoshop) files are made up of pixels and can be distorted when enlarged or scaled up. Vector files will not do this they remain clean and crisp as they are scaled up or down. Vector files are made up of mathematical calculations on a virtual grid not pixels all done by the computer as you draw. They can be import into most other CAD drawing software as well. Large plans in Vector can also be printed on normal 8.5 X 11 printers and paneled together for quick build plans. The most common Vector CAD files are DXF however EPS is also very popular. Don't get me wrong I love Photoshop too it works great for Photo pixel alterations but for line work you just can beat VECTOR IT RULES!
A real good low cost easy to learn CAD Vector program is Delta Cad it is a free download try it everyone will love it for 2D model designing work in Vector. Also another cool 3-D modeling software tool is RC Cad it will export in DXF as well very cool. For you wing designers try Compufoil it too exports in DXF even fully lofted wing plans with over 300 airfoils way cool.
http://www.deltacad.com/demo.html
http://www.rccad.com/
http://www.compufoil.com/download_cf.shtml