From a purely amateur point of view, it may contribute somewhat but I think the overall design of the wing, i.e. aspect ratio, wing span, etc. and construction material would contribute more. The EFlite Opterra has a flat bottom wing but look at what this guy does with it. Practically every maneuver, that’s a no-no for flying wings is a non-issue with it. Maybe the larger winglets and vortex generators behind the leading edge on top of the wings and another set just ahead of the elevons on bottom cures it.
I think the video that @Wmacky referred to points to the issue. The condition he described at about 1:10 seem to describe exactly what happened on your maiden flight… downwind, then turn upwind and half through the turn is when it loses it.
In any event, hopefully your intended mods to strength the outer panels eliminates the issue.
Thanks for the tip. I really like the Opterra. However, it’s an apples to oranges comparison. It is also twice the price. E-flite really tests there designs. I used to review them. Yet, another video on a perfectly calm day. I will likely still strengthen the wing ends and re-test as a plane but perhaps someone else can pick up the project.
I’m moving on to another project; the Nimbus 1800 VTOL. I like the medium-sized dedicated QuadPlanes like my Bix3 and mini Talon. For the larger QP conversions, it makes more sense to think about a tilt-rotor design. Less motors, less weight, less drag. The Nimbus 1800 breaks down or builds up in seconds. Using robot servos takes all the drudgery out of the tilt-rotor mechanism. I may start a thread in the new VTOL forum because the information on this conversion is spread all over.
After seeing some recent efficiency logs of the Nimbus, I’d recommend the EVE-2000 far before the Nimbus. You should be able to get 2-3 hours out of it while having basically the same setup geometrically.
Thanks for the tip and the link! I have been following the FPV Planes forum on RCG and see the various models, but I don’t fly long-range FPV so efficiency isn’t one of my goals. In fact, if I fly over 15 minutes, I get tired!
My main goal is to take-off and land in a small area, hence the VTOL. I also really like a larger plane that assembles fast at the field. Using a 6s 10Ah Lipo pack, the Nimbus duration is around 1 hour including take-off and landing. I can’t imagine flying even mapping missions longer than that so it will be interesting to see if your warning comes back to haunt me.
I would DIY the mounts. The conversion kit by kris uses the original motors along with a different UAVS approach than my plan. I plan to mimic the FoxTech approach using stock parts and the new motors for mapping. The two front Sunnysky x3520 520kv motors are available at BuddyRC for a $35 savings over the FoxTech version.
I started the wing tip mods by gluing a piece of flat carbon rod into a slot I cut. The rod was then glued with Foam Tac. It really strengthened the thinner outer half of the removable wing section. The inner half was already solid so it didn’t need reinforcement. Next, I’ll add a second joiner tube…
I used some carbon tubes that I had on hand for the second joiner tube. The larger tube glued into the main body had a 12mm outer diameter and a 10mm inner diameter. The wing trailing edge seemed weakest so I decided to add the second joiner in the “C” section of the winglet. I’ll need to let the Foam-Tac glue dry over night before I test the strength added to the joiner.
It will be interesting to see if this corrects the issue. Keep us posted. If it does, I hope you would reconsider finishing the project. I still believe that if the tuck issue is resolved this could be an awesome platform as Marco’s videos suggest.
Congratulations on your mini Talon conversion to QuadPlane!
Here is my current param file. Keep in mind that Flight Mode 1 has been changed to Manual and Flight Mode 2 to FBWA because I am currently flying it non-VTOL for testing.
Normally, my Flight Modes are:
QSTABILIZE
QHOVER
FBWA
CRUISE
LOITER
QRTL or AUTO
Post some photos of your mini Talon QP over on my build thread please. It would be nice to show some various solutions.
I made one more mod before starting the other wing. I noticed that the unused flap could be anchored to the winglet to make it more solid. I made a small balsa insert and glued it using Foam-Tac. Now the flap corner and winglet are secured together. Once you paint it, it is hard to see.
This was a low wind test with the modifications to strengthen the wing extensions. When flying from 15-23mph in low wind, as shown below, the FX-79 flies great! However, when speeding up, it still has a tendency to tuck so my modifications did not seem to work.
I plan to re-mount the quad booms next and try another test with Q_ASSIST_SPEED set to 15. Perhaps if I keep the FX-79 flying at a reasonable speed then the Q_ASSIST_SPEED feature can be set to keep it from stalling.
The two motors were replaced and the quad booms are getting re-mounted on the FX-79. It will be interesting to see if it works better as a QuadPlane using slower speeds. If not, then this project will be concluded.
I recently bought an E-flite 2m Opterra. It is a beautiful design! Most people don’t know the designers but I have reviewed many of their models in the past and was present in Toledo when George Hicks won the first indoor flying championship. It was a long time ago!
The Opterra wing is not a flat bottom design like the FX-79. It is semi-symmetrical like my Zagis and FF6 wings. This design is made to glide well and be efficient in the air. I will likely make an APM Plane Fall/Winter project out of it, adding the retracts so it can take-off from the flying field.
I re-mounted the quad booms after testing the FX-79 as a normal wing. The FX-79 Buffalo QuadPlane Flight Test 2 was successful! After transitioning to FBWA mode, I throttled back to less than half and the wing flew fine in 5-10mph winds. This was a promising performance so I will plan to test it again.
I’m still using the PIDs posted in the July 4th .param file above. I have only changed the two Flight Modes back to using QSTABILIZE and QHOVER since the quad booms were re-mounted.
I can post them again soon since I realize their is a time limit on this forum for keeping files.
