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Old Aug 05, 2015, 12:48 PM
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Ahhgh! Not ANOTHER new plane!
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X-35, an F35B STOVL EDF

A company in China, RCSCOPE.COM, has produced an EDF model of the F-35B that exhibits vertical and short takeoff & landing capabilities along with forward flight. I ordered one direct from them, and received it via EMS this morning.

All I have done so far is inbox it, but I have been following this model for some time. It was introduced in China earlier this year, and there are a number of YouTube videos showing it flying.

There are two EDF fans in the fuselage, a forward one fixed blowing downwards when active, and a rear one that is articulated. The fan housing rotates, from horizontal, to 45 degrees down, to full vertical. Inside the housing, there are vanes that direct airflow from side to side. There are no wing thrusters. Roll and sidslips in hover mode is accomplished by the vanes. Pitch is handled by the fore and aft fans. I'm not sure there is any yaw capability. An accelerometer/gyro board, adapted from the burgeoning multirotor hobby, keeps it stable (we hope!). Control surfaces in forward flight consist solely of elevons.

It's painted light gray top, white undersides. If it flies, I'll give it a Yuma USMC paint job.

I'll be posting more as I progress. In the meantime, here's a parts photo and a video link to tease you!

rcscope new trailer (2 min 0 sec)
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Old Aug 05, 2015, 02:54 PM
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I've been following this one as well. I haven't heard anything about it in awhile. I'm looking forward to your flight report. How much did it cost?
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Old Aug 05, 2015, 03:59 PM
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Ahhgh! Not ANOTHER new plane!
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Mine cost $399, EMS delivery included. I think this is reasonable, for what is a low volume, high novelty, complex product, as long as it works, which remains to be seen!

Transitions will be an adventure. Per the manual, when going from forward flight to hovering, the main EDF shuts down while it rotates to the vertical position, takes one second. There's a leap of faith! Going from vertical or 45% to forward flight, supposedly it takes more time, but the translation is unclear.

An hour or so into it, I would say it's a bit rough. The foam is non-foam safe (I always check), which is a lot lighter and consequently more fragile than usual. The main gear mounts were glued so sparingly, I pulled them off with finger pressure.

At this point, my criticisms are not meant to discourage anyone, just keeping eyes open.
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Old Aug 05, 2015, 04:14 PM
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The price does not surprise me. I agree, reasonable as long as it works well. It sounds like they eliminate every gram of weight that they could. It takes a lot of power to hover a EDF. Hopefully your flights will go without a hitch!
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Old Aug 05, 2015, 08:29 PM
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fly like an EAGLE ;)
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robert ...looking forward to your report! such a neat model!
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Old Aug 05, 2015, 08:45 PM
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Update; both fans, fore and aft, have directional vanes. That being the case, maybe it can yaw. I tried a hover hop, but didn't want to get too high in my driveway. It worked, but I need a larger, softer area to experiment. I'll be putting anti-scuff tape on the wingtip so. They'll need it.

I'm trying to work out the mode change procedure. It's eluded me for now, but a challenge is a challenge!
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Last edited by Robert Stinson; Aug 05, 2015 at 09:26 PM.
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Old Aug 05, 2015, 09:11 PM
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I've been watching this one too. Looking forward to your build and flight reports!

Pat
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Old Aug 05, 2015, 11:51 PM
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Ok, another update: the transition from VTOL or STOL to forward flight is not defined clearly in the manual. (Oh by the way, there was no printed manual in the box. I'm using a PDF version Rcscope sent me.) It said transition took 25 seconds, something I couldn't imagine in flight! But, it's true. The rear fan slowly rotates up, actually in steps, while the front fan still runs. The plane will be accelerating during this time, the PCB stabilizing the plane. Finally, the rear fan has gotten horizontal, the plane is going forward and the front fan shuts off and the doors close. Pretty neat! Of course, I've only seen this on the bench.

Quality-wise, there are some more bumps. A couple door hinges weren't glued well.
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Old Aug 10, 2015, 07:01 PM
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Thumbs up or down?

Well guys, I have to say in my opinion this is a bust. I can't recommend it.

Servos that operate the fan doors are tiny, which is to be expected. However, at least two are malfunctioning. They are inaccessible without foam surgery. One main gear simply fell off, as I'd mentioned before.

The plane has enough power to lift off, but every time, about 3 or 4 seconds into flight, it drifts left straight into the ground. Again, the vanes are operated by small servos. I don't think they can handle the stress. The electronic retract mechanism that swivels the rear fan won't travel reliably, which would result in a crash if in flight.

Speaking of foam, this is EPS. Which doesn't stand up to stress either. The plane is incredibly fragile. Pre-flight testing has banged it up a lot.

A shame. I'll work on it, considering it a challenge, but confidence is low.

I recently bought a CL-84 Dynavert tilt wing VTOL prop plane. What a difference. That one is a winner.
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Old Aug 10, 2015, 07:12 PM
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You have given up on it in two days? How many flights were attempted? Is there any gyro stabilization used?
Perhaps a little more work and patience might get it going?
Please tell us more and provide some technical details.
Thanks
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Old Aug 10, 2015, 08:43 PM
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Ahhgh! Not ANOTHER new plane!
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Quote:
Originally Posted by 4stripes View Post
You have given up on it in two days? How many flights were attempted? Is there any gyro stabilization used?
Perhaps a little more work and patience might get it going?
Please tell us more and provide some technical details.
Thanks
Check my first and second posts describing the gyro operation.
Check my last post regarding the quality problems and flight behaviors.
I have been test flying it every day since it arrived last week.

Per my last post, I will be working more with it. I'm posting my warning so that prospective buyers won't be expecting to shake the box and have a problem-free aircraft float down to the floor.

I gotta call me like I see em. Having flown literally hundreds of planes over the years, I can recognize a problem plane when I see one.
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Old Aug 11, 2015, 11:47 AM
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That is disappointing. Sounds like they have a good concept, but bad servos will only get you so far.
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Old Aug 11, 2015, 12:13 PM
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Some can be accessed by performing surgery on the foam. The breaking the original loose. All are just glued on.

All of the door hinges need to be re-glued, four or five have already come off the surfaces, which makes the clearances suffer. One big problem is, as it came, when the main fan rotates down, the doors surrounding it are supposed to open. They don't do it quick enough, and get jammed. Bad deal if it happened in flight, when it thinks it's in VTOL mode but the fan isn't pointed down. I fixed that by shaving 1/8" off the doors and adding some plastic to push the doors first. The top front fan doors also can jam, mainly because the hinges are sloppy. I shaved those too to make them work.

I'll continue to tinker.
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Old Aug 11, 2015, 01:41 PM
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It's a shame to hear of all the problems with this bird. I was really looking forward to a scaleish F-35B.

Hope you get it sorted Robert!

Pat
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Old Aug 19, 2015, 12:47 PM
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Has anyone considered the fact that it hovers and therefore requires hovering skill?
What I'm saying is that no matter how many gyros you put in any aircraft, you need some basic skills keeping it up. The gyro drift is a setting issue for sure: either gyro sensitivity or some basic mechanical setting to be adjusted.

Honestly, this is the first in its kind as far as I know and I suppose it deserves some more attention. Maybe some more manufacturer support to get these things sorted.

About the drifting to the left. Check out this video. In hover you see, based on the elevons, that a significant amount of right-aileron is applied.

I would like to see a helicopter pilot try to set it up for hover.
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Last edited by RNAF; Aug 19, 2015 at 12:59 PM. Reason: added video
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