Official E-flite 650mm Convergence VTOL Thread

[Twowingtj]

UPDATE: With all the tweaks as mentioned in post #54, I flew the Convergence 3 flights today. I did a right flip, left flip, front somersault, back flip and all worked beautifully. It was just too cold to get a video. Transition MC to AP and back was seamless, as was from Stability to Acro and back. In AP flight, flipping to Acro resulted in zero change in altitude. It stayed level and straight as an arrow. Shutting down the throttle in AP mode in either Stability or Acro resulted in a nice controlled, shallow descending glide, nothing surprising. Powering back up when it got close to the ground was quite predictable. It just went faster, leveled out and easily ascended. Took off from a table top and landed back on the table.

Thanks for the flight reports. Sounds like you've got some of the design quirks worked out. I had a chance to test what pos 1 on my stability to acro switch does. It maintains stability mode. Seems that the FC doesn't go into acro unless it sees the 100% signal.

Also a word of caution on the 150% on the UP elev servo travel. If you pull back full elevator and give full rudder inputs, it tries to push the nacelle past the mechanical stops. When you do this you can see the nacelle control arm twist. This could be contributing to the ball link failures we've seen. It still happens to some degree at 120% UP travel and full rudder input.

[xviper]

Also a word of caution on the 150% on the UP elev servo travel. If you pull back full elevator and give full rudder inputs, it tries to push the nacelle past the mechanical stops. When you do this you can see the nacelle control arm twist. This could be contributing to the ball link failures we've seen. It still happens to some degree at 120% UP travel and full rudder input.

I've also mechanically adjusted (minor) the linkage on the nacelles. When full back stick, it doesn't hit any end stops, but I will double check. Thanks for the heads up.

[Twowingtj]

xvip, I'm curious where your CG is after your mods, both with nacelles up and forward. Have you noticed any difference in speed at WOT in ap/acro mode? It seems like it should be better since all thrust is foward instead of partially up to make up for a forward CG. Is there any difference in aileron responce since the nacelles don't travel up as far?

I just finished getting caught up in the RCG thread. No one seems to have taken your approach yet. Your changes seem to make good sense. I'm lookin forward to more of your flight test results.

[xviper]

I originally had the CG where it stated in book. This put the 2200mah, 3s battery very close to the front of the compartment. I took a closer look at the nearest equivalent airplane, which is the Delta Ray. It's CG is a bit different. I've always felt that the CG on the Convergence is a compromise between MR and AP mode. Those nacelles swiveling forward like that changes the balance a lot. I didn't like it. My battery now sits as far back as possible. This involved some removal of foam from the top hatch to make it sit flush. This puts the CG much further back than stock. In MC/stability, no difference is seen as the FC tries to keep the craft more or less level. In MC/acro mode, it's not a big deal as one is forced to fly it all the time anyway, so keeping it level becomes instinctive.
In AP/stability, again no difference as the FC does it's thing. In AP/acro, the couple of degrees of reflex in the elevons does the trick and keeps the plane flying straight and level with no pilot input. IMO, I think this thing should have been balanced more for AP mode. MC mode is used primarily for take off and landing and for doing tricks. For tricks, you're flying it all the time anyway.
As for speed, no, I detect no difference. Note that I've made my nacelles closer to level (but not quite exactly level). Knowing that in AP and stability mode, the FC dials in its own reflex to keep it flying level. By manually setting reflex on the elevons, flipping from stability to acro AP mode doesn't change anything. Where the plane used to normally take a nose dive, it now just stays put and keeps flying level. In order to get more speed in AP flight, one would have to rebalance the whole plane after taking all of the reflex out. Quite frankly, that 2 - 3 degrees of reflex doesn't contribute that much drag, IMO. In the current state of things, that would require the addition of weight to the rear of the plane and that is more undesirable than losing a bit of speed. Additionally, the use of weights could upset the balance in MC/acro mode. I believe the FC can adjust for weight balance in MC/stability mode, but the pilot may have to do more work in MC/acro mode, which is not a big deal for anyone well versed in quad operations.
To go back to my thoughts on motor attachment, presently the motors swivel at the rear of the assembly. When going from one mode to the other, the weight of that assembly moves fore/aft a significant amount. If the motors could be mounted on something like between the forks of a fat tuning fork, then rotation would not affect where the mass goes fore/aft. This would allow for the same CG in both MC and AP flight. It could fly like a regular multi-copter and more like the Delta Ray, which actually is a very nice gliding airplane and docile, too. This could be a nice project for someone with more manufacturing skills than I (and maybe a 3D printer). Perhaps Horizon will figure this one out for a later version. ;)

As for further testing and experimenting, I think I've made it as good as I can. It flies great, without any of the quirks as reported by some. It does tricks real nice, glides quite well now, flies quite slowly when desired and doesn't need a lot of area to fly it in AP mode. I'm just going to have fun with it and quit messing with it while I'm still ahead.

[Brandon Moon]

Got two flight on this thing, end even though it flew well (When it will work?), It has quit working again....have had nothing but problems with it, and now have asked for and RMA return label from CS so I can return it for full refund..... IMO this is a HH's big FAILURE and lacks highly in reliability. Thoroughly dissatisfied with this model :@

[xviper]

Got two flight on this thing, end even though it flew well (When it will work?), It has quit working again....have had nothing but problems with it, and now have asked for and RMA return label from CS so I can return it for full refund..... IMO this is a HH's big FAILURE and lacks highly in reliability. Thoroughly dissatisfied with this model :@

That's a bummer, BM. I suspect that the QC for this plane, especially the flight controllers has been very sketchy. Mine exhibits a "brain fart" now and then but not to the extent that it has caused any problems for me. It's a complicated control system and they didn't spend enough time on it, but they also diverted too much time away from the hardware that the plane is built upon.

[Brandon Moon]

It's on its way back to HH to be looked at and fixed

[Aros]

I will definitely need to snag one of those. Looks like a lot of fun, but I hope the quality gets improved as per Brandon.

[Brandon Moon]

I will definitely need to snag one of those. Looks like a lot of fun, but I hope the quality gets improved as per Brandon.

I would hold off on getting one right at the moment,,,,, lots of issues, and though fun to fly (When it works?) I can't recommend it for the amount of money spent on it.....MAJOR Quality issues IMO. My opinion may? change once I get mine back and they tell me what was wrong with it? I'm usually pretty darn savy in fixing and figuring out this stuff, but this one?....NOT!!!! I did everything but change the ESC's and Motors.

[xviper]

After many, many flights, I finally got a chance to do a video with my Mobius "hat cam". Although I've had about 2 flights where there was a little glitch (flight controller had a small brain fart resulting in some instability), none have ended up with a crash or incident of any kind. Today's video flight was glitch free and near perfect. That little bobble just after switching to acro mode was me testing the sensitivity of the controls for the next few stunts. I normally fly on an Admiral Pro 2200 mah, 3s, but this was the first flight using the Turnigy Graphene 1800 mah, 3s, 65C. Flight time seemed about the same and the plane had a bit more umph. Came down before the LVC hit and had ~3.9v/cell. Going from stabilized to acro in airplane mode was seamless with no change in altitude. Cutting throttle while in acro, airplane mode showed very mild glide and uneventful.
(Best viewed on YouTube in full screen.)

[ace184]

Four people in our club have these. All 4 have lost power and fallen out of the sky. I've seen where these things are really good, or really bad. No in between.

[xviper]

Four people in our club have these. All 4 have lost power and fallen out of the sky. I've seen where these things are really good, or really bad. No in between.

That's very discouraging. I flew mine today again for 3 flights. All good. The only thing of note was my last flight was on an old battery and it hit the LVC and it wouldn't transition. Landed it with plenty of time and control.
There are 2 others at my field and one of them had a crash but that was due to the rear motor housing coming unglued mid-flight. After fixing it, not another problem.

[ace184]

That's very discouraging. I flew mine today again for 3 flights. All good. The only thing of note was my last flight was on an old battery and it hit the LVC and it wouldn't transition. Landed it with plenty of time and control.
There are 2 others at my field and one of them had a crash but that was due to the rear motor housing coming unglued mid-flight. After fixing it, not another problem.

The one that crashed today crashed during transition from hover to flight mode(don't know exact terms). Two days ago one crashed while the guy was in hover mode just getting the hang of it and lost all communication. The third one was during transition as well. Not sure about the fourth one. The guy who crashed today got so fed up with the plane, he gave it to one of the other guys that has one to use as a parts plane.

[Brandon Moon]

Still waiting for mine to be returned....Still no contact from HH as to what was wrong?

[Alpha]

I'm still waiting for mine to arrive in the first place :/ Holding out hope!

[xviper]

What's wrong with HH these days? They're either really busy with customer issues or they are backing away from this plane, hoping the next production run will have resolved the problems. You'd almost think that they'd do their best to get one of these to one of their bigger customers (Alpha) so he can sell a few more. :huh:

Weather has warmed up a lot lately and I've been flying mine every day. Still very pleased with it.

[xviper]

The "twins". Will try for the "triplets" next time.

[Alpha]

I wish, brother. But our customers come first, so we want to deliver everyone's preorders first. Only after every preorder is fulfilled will I want to accept one. Hopefully that all happens very soon!

[xviper]

Alpha, fine sales ethic. As it should be.

[Twowingtj]

Finally going to get a chance to fully maiden mine tomorrow. Hovered in the house fine. Many transitions on the bench to make sure motors didn't cut out. Made the physical set-up changes that Xviper2 is using. Better ball links and rods. Fully charged good quality batteries and an Atomic Fireball candy(a must have for any of my maidens).