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Author Topic: Taildragger Mk.1 Testing Continues  (Read 99 times)

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Offline Deerslayer

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Taildragger Mk.1 Testing Continues
« on: August 19, 2017, 03:07:18 PM »
 Thank you, Wilf, Harold and Terry for your assistance during a very interesting series of tests. Here is the product of your efforts - the Ups and Downs of flight testing this bird. Having video is very useful, as I can run it in VLC, slow motion and stop it, to see what happens during the most critical second or two of a launch, for instance.

 There may or may not be more flying of this machine, as it has undergone some sessions with the glue gun and the foamboard itself is getting sort of punky due to the paper detaching. I think that we may have gone past the Flypaper Golden Ratio of hotglue:foam, so this may be the end of my work with this one. The next one is radically different, still a taildragger wing, twin-engined, vectored thrust but much simpler. It will be much easier to get going, due to my experiences and learnings to date, plus the extensive programming of the DX9 which will be essentially unaltered for the new machine.

 Meanwhile, rumour has it that there may be one of these beauties incubating in the fevered mind of Flypaper, or it may already be on the operating table! Go Gord, Go!

So, here is the whole sordid affair:

https://youtu.be/YebpBz2wan4
« Last Edit: August 20, 2017, 12:49:42 PM by Deerslayer »
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Re: Taildragger Mk.1 Testing Continues
« Reply #1 on: August 19, 2017, 07:52:43 PM »
Looks promising Gary.
 Better get back at mine.
« Last Edit: August 20, 2017, 12:49:26 PM by Deerslayer »

Offline Deerslayer

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Re: Taildragger Mk.1 Testing Continues
« Reply #2 on: August 20, 2017, 06:59:22 AM »
Thanks for the encouragement, Gord.
 I finally learned something regarding the ROG takeoff situation (slow leaner here!). The following discussion is for my own benefit and perhaps for yours, Gord.

The above videos clearly show the problem I have been having, a combination of a questionable Thrust Vector (TV) mixing strategy and my slow reaction time. Just to make things more interesting, I avoid getting into using a Flight Controller, the objective being to do all the complex stuff within Airware, the Spektrum system which operates the DX9 and other DX-series transmitters. I am very happy with this latter decision. The former issues are correctable, methinks.

The one perfect ROG launch was due to my switching Flight Modes and thus disabling vectoring at just the right time, within a second or so of liftoff. The subsequent crunch was due to a completely unrelated issue - the plane normally flies like it is on rails once airborne and approaching horizontal, as the hand launches have proven.

 In Launch and Landing Modes, I have Elevator mixed to Thrust Vectoring (TV). This seemed like the right thing to do, as the motors have to be rotated almost vertically for ground clearance of the props and, secondarily, to provide immediate launch thrust. So, I have coupled TV into Elevator for this. The result is that the takeoff is extremely quick - sometimes, the machine does an immediate back-flip right off the ground. If I do get airborne, I have to immediately flip to Cruise Mode to cancel TV and have normal, pitch stable control. Similarly, in Landing Mode, with this coupling enabled, it is way too pitch sensitive. The coupling can still be selected in Cruise Mode via a normal switch, to perform its big trick, the wicked backflip(s).

 So, I reason that the solution is NOT to couple TV to Elevator for Launch and Landing Modes. During Launch and Landing Modes (in the latter, it may be left as switch selectable, as there is much more time to set up for a stable approach and landing).

 I will reprogram the Launch Mode, at least, so that we have full TV at low Throttle, gradually being reduced as Throttle is advanced. This will take a bit of tinkering, as we have to judge at what point the machine will have begun rotation, is likely to become airborne, will have prop clearance with the motors returned to align with the chord line, and then completely dump TV so that it can be flown out normally. This will give me lots time to move from Launch to Cruise Mode without any other distraction - as long as we have a high Throttle setting in the Launch Mode, TV is effectively off and the switch to Cruise will ensure that Throttle changes do not re-engage it.

 To try this, I may drag my poor, somewhat abused  Tailsitter Mk.1 out for another "kick at the cat can", rather than sidelining it and moving the gear to the new machine.

 If  one of my conscript videographers is available, I may even be able to document the whole sordid affair!

 If there is anyone else out there who is weirdly inclined to play with this kind of stuff, I can perhaps offer some help.Misery loves company? This plane is terrific in the air, the fully back-flips are something you will not likely see on anything else, the plane itself emerged from 2 sheets of Elmers foamboard and the only real complexity is in the DX9 programming, for which my SPM is readily available as at least a starting point, along with spreadsheet documenting all configurations and settings.
 
« Last Edit: August 20, 2017, 12:48:54 PM by Deerslayer »
My purpose in Life is to serve as a Warning to others