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Oct 22, 2020, 08:03 AM
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Lufo's Avatar
Between the 7 and 11 second mark of ROG there is a chance the tow line went slack and wrapped on the horizontal stab. But during flight the tow does not behave like it has a fouled control surface.

At about 20 seconds, depending on view perspective; the glider moves below the tug and we see the tug nose go high a bit, glider move up and tug nose levels. At about 22 seconds tug and glider are about even in the same altitude but we see the tug begin a right roll. The tug nose is only slightly up during the initial roll start and the glider is level.

In one perspective I can see where the glider is to the right of the tug and in another it is behind the tug but does not hold a steady altitude.

This is why a bright fluorescent tow line is wonderful.
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Oct 22, 2020, 08:37 AM
Registered User
Lufo. You are right on it. It could be coupler pilots making mistakes. The video is not good enough to be sure of what happened. An experiences tug pilot that has problems with a large glider not flying where it should be and one with a similar tug. Even then it just a guess as to what happened.

Only the actual pilots know what they did.

Art
Oct 22, 2020, 02:35 PM
Registered User
Lufo's Avatar
As you mentioned the video quality is poor, as well as the sky is overcast and both planes merge well with the background sky. Tow line is invisible even with the planes on the ground. Anything I come up with is pure speculation and I can come of with several of those.

Of course, the best solution is to go the Repository of Facial Recognition page of Giuseppe Palummieri and ask him. Not being a member of RFR I cannot do so.
Oct 23, 2020, 01:17 AM
Entropy is happening!
Jim.Thompson's Avatar
Quote:
Originally Posted by mawz
FrSky ACCST D16 v1 Uncommanded Servo Movement bug?
Unexpected barrel roll would be a classic example of it.
After watching the video many times, I am of the opinion this, or some other similar equipment malfunction caused the snap roll to the right and the subsequent crash.
I lost a 1/4 scale tug on maiden flight due to just that problem. It took us a while to come to that conclusion; I have since changed back to the FrSky D8 system, which I have more confidence in.
The roll happened far too fast for it to be a stall or the tow line catching a control surface. Besides, at that speed, I would expect a normal line will stream out fairly straight anyway, not fall below the elevator. Unless of course, it is 5mm rope!
As for the "stall spin" theory?
No; it was flying quite fast, I cannot accept that reasoning.............sorry!................

Jim.
Oct 23, 2020, 09:55 AM
Registered User
It may have been servo bug but the spin started right after the glider dove some then the tug started to spin.

Art
Oct 24, 2020, 12:47 AM
Registered User
scott page's Avatar
Quote:
Originally Posted by mawz
FrSky ACCST D16 v1 Uncommanded Servo Movement bug?

Unexpected barrel roll would be a classic example of it.
Not UCM because the plane rolled right slightly once, then twice, then all the way. The UCM would be all at once - no tentative moves before hand. This looked like pilot disorientation which resulted in a stall.

The other thought I had was WiFi interference from nearby houses -- but again -- the first movements look more like pilot searching for orientation.
Last edited by scott page; Oct 24, 2020 at 07:23 PM.
Oct 24, 2020, 03:09 AM
launch low, fly high
Classic silhouette pilot failure. The pilot sees mostly a silhouette of the plane, and when the pilot thinks the plane is rolling left, the pilot gives a right roll command. The plane was actually initially slightly rolled right. The right roll command increases the right roll. The pilot thinks that the plane is increasing the left roll angle and adds right roll command. The quick result is that stuff happens...

Almost everyone has had this happen to them. Many blame the result on the radio (anyone remember the 3IM "crashes" ???). When the plane responds in the opposite of what you expect, it is difficult to not "double down" on the stick input. I've learned better. This is especially pertinent when the plane is backlit so that one mostly sees the outline of the plane.
Note carefully that the problem ensues right after the plane is almost perfectly perpendicular to the observer, which is the most likely attitude for misunderstanding whether the roll angle is towards or away from the observer.
Oct 24, 2020, 05:55 AM
Entropy is happening!
Jim.Thompson's Avatar

Bingo!


Quote:
Originally Posted by Joe W
Classic silhouette pilot failure. The pilot sees mostly a silhouette of the plane, and when the pilot thinks the plane is rolling left, the pilot gives a right roll command. The plane was actually initially slightly rolled right. The right roll command increases the right roll. The pilot thinks that the plane is increasing the left roll angle and adds right roll command. The quick result is that stuff happens...

Almost everyone has had this happen to them. Many blame the result on the radio (anyone remember the 3IM "crashes" ???). When the plane responds in the opposite of what you expect, it is difficult to not "double down" on the stick input. I've learned better. This is especially pertinent when the plane is backlit so that one mostly sees the outline of the plane.
Note carefully that the problem ensues right after the plane is almost perfectly perpendicular to the observer, which is the most likely attitude for misunderstanding whether the roll angle is towards or away from the observer.
This is the most cogent explanation I have read; very good!
I am now convinced this is the explanation.
I certainly have had this happen and I also have learned better, but perhaps not the best way.
I give the aileron stick a small blip first to confirm that I have the correct direction or vector. Then, and only then (if times permits), do I apply a more confident and effective degree of stick command.
The downside to this habit, is that the plane is not flown quite as smooth as good flyers can.
What do you do Joe?

Many thanks,

Jim.
Oct 25, 2020, 10:25 PM
It's not going to build itself
TRISME's Avatar
I thought it looked like an orientation problem too. I've had a towline wrap around the glider wing and then release, it's not subtle! That tug looked kind of underpowered, the wing looked kind of small for the fuse or mounted too far back as well. Probably an illusion. Bummer to lose a plane, they all have an expiration date.
Tom
Last edited by TRISME; Oct 26, 2020 at 10:18 AM.
Oct 27, 2020, 11:12 AM
Registered User
I don't aerotow but to me the tug seemed marginal. I would think it's way safer to have a tug with way more power than you need. For one thing you could gain serious altitude in a short period of time, also it would mute any forces in the tow line.
Oct 28, 2020, 01:58 PM
Wakka Wakka
streborz's Avatar

"What Happened" is What Happened Afterwards


The rebuild video is fantastic.

How To Rebuild Balsa Plane - RC Airplane (15 min 30 sec)


Great Building Skills and Initiative.


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