Baudis Fosa F3B/F3F - Page 5 - RC Groups
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Nov 21, 2010, 08:30 PM
Registered User
Here is the hardware. Anyone who has built a Cyril or a Ceres Lift will recognize the parts.

The servo mounts are designed for some F servos. The 378 is the same thickness, but the shaft is a little closer to the edge of the case.

The fiberglass ball bearing holder has to be sanded so it can slide over a little. The ply in that area has to be filed a little since the shaft is moved towards the edge. And the area of the frame near the shaft has to be trimmed a little so that he servo slides all the way to the top of the mount. The extra ball bearing really helps make the surface tight. The fit of the wiper in the slot is excellent. I glue the fiberglass piece to the mount outside the wing using a machinist square to make sure that the shaft is aligned properly with the servo.

The only other thing to add is is some ply to screw the servo to the mount. 1/8 is not thick enough, You need another 1/32 shim to get the right thickness. Wait to add that until you have finished the servo mount.

It would be nice if we could get JR 378 or 388 mounts with the models.
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Nov 21, 2010, 09:02 PM
Detail Freak
target's Avatar
My Cyril came with ply mounts for the 378's.... Nothing a guy like you couldn't work around, but the dedicated 378 mounts were easy to use, Mike.
You might call Annette/Bob tomorrow if you can stand the delay.
The 378 mounts have 1/8" ply doublers that glue onto the 1/8" frame.
Pic attached, not the best, sorry. You get the idea.

I can't wait to hear what your impressions are of the flight differences between the Fosa and the Cyril.

Last edited by target; Nov 21, 2010 at 09:08 PM.
Nov 22, 2010, 12:44 AM
Registered User
The stock wing wire weighs around 62g total for wing, fuselage, plugs. It's 22 guage wire. I make my own wiring by using 24 guage for the power and 26 for the signal with teflon coated wire. Final weight is 48g for the wing wiring. The teflon coated wire is also smaller so there is a little more space in the fuselage.

In addition to heat shring tubing, I use some hot glue to add to the strain relief. .75" fiberglass braided tube (electronics stuff) is also handy to prevent any wire damage if you don't glue in the plugs in both the wing and fuselage.

When putting the wire into the fuselage, remember to put the wire through the slots in the bulkhead to prevent any interference with the ballast tube.
Nov 22, 2010, 12:54 AM
Registered User
I mark up the wing where the rear subspar slot is located and where the RDS slot is located in the wing. This way you can be sure the linkage is pointed where it needs to go.

Do both ailerons at the same time and both flaps at the same time to make sure both are set up close to the same angles.

A silver sharpie helps to mark the wing where the mount needs to be glued to the wing. Glue the ply to the wing and also glue the fiberglass bearing plate to the bottom skin if you can.

Blue tape helps to keep epoxy off the wing while working on the install. Also mark the RDS shaft for the side you expect to see on the bottom.
Nov 22, 2010, 12:56 AM
Registered User
If you go with a 5-cell pack, the fuselage is designed for an "interesting battery layout. Two cells end to end at the front of the pack, one vertical, then two more cells.. That is the shape that fits the most forward.
Nov 22, 2010, 01:01 AM
Registered User
The fuselage servo tray is a little different. The rear bulkhead also attaches the ballast tube to the fuselage. The rear servo slides into a slot in the bulkhead because the ballast tube will prevent access to the rear of the servo. A cross piece of ply screws to the frame to secure the front of the rear servo and also the front servo. This way the servos remain removable even with no access to the rear of the one servo.
Nov 22, 2010, 06:54 PM
Registered User
OK, here are some pictures from the first trip out to the field to fly. Finished weight is 2080g. Wing ballast which is 720g.

So here is your one data point you can extrapolate to whatever you want on performance.....

Temperature was in the mid 60's and winds were light from the SW. It had been cloudy earlier in the day but there was a little bit of lift around, not much. For winches I had the large drums on and 1.12 megaline. Not the best choice, but I didn't want to break any line since I didn't have much time. After four flights, some minor CG adjustments, things were starting to work going up the line. 876ft. So time to put in the 720g of ballast. Next launch is 886ft but still in need of some adjustments to flaps/elevator presets on launch. Flights 9 and 10 are 874ft and 902ft with the 720g of ballast and not much wind. But the model is tracking well and pulling pretty good for the conditions. It's getting late some one last launch at 875ft without ballast and 11 minutes of durating with the sun setting.

But it's one data point. Not enough time to switch between the Fosa and my Cyril, Shooter, or Freestyler.

This weeks outlook for weather sucks. So I need to power up the mill and make some tungsten ballast.
Nov 22, 2010, 07:31 PM
Challenge is rewarding
djklein21's Avatar
mmmm, new B plane in grass, mmmmmm
Nov 22, 2010, 08:01 PM
Registered User
Originally Posted by djklein21
mmmm, new B plane in grass, mmmmmm
It doesn't mean that you still won't happen to hit the gravel road along the edge. They attract new models with no scratches.
Nov 22, 2010, 08:26 PM
Daryl Perkins's Avatar
Very nice Mike - Thanks for the updates!!!!
Nov 22, 2010, 10:02 PM
Detail Freak
target's Avatar
Sounds very promising, Mike.
Congrats on the successful maiden (what else would we expect from you though!).

PS. I know that you know we all want a comparison between Cyril and Fosa when you believe you have an opinion formed. Allegedly the Fosa will out launch the Cyril in most conditions. Please try to find a "con" of the new design if there is one apparent. Thanks in advance.
Nov 22, 2010, 10:05 PM
registered user
Great report and pics !!!
Nov 22, 2010, 11:57 PM
or GPS, F, J, K, or even TD
FLY F3B's Avatar
That FOSA looks so sweet! Have fun with it Mike.
Nov 23, 2010, 12:04 AM
Registered User
Thanks for the info Mike. Are you happy with its handling compared to the Cyril, Ceres?
Nov 23, 2010, 12:27 AM
Registered User
Avaldes's Avatar
SA-WEET model!! I might need one of these

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