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Author Topic: Tailsitter Mk.2 Test Flight #1  (Read 207 times)

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Online Deerslayer

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Tailsitter Mk.2 Test Flight #1
« on: July 19, 2017, 06:06:33 PM »
Here is a little video I cobbled together for your amusement.

My overall objective was to create a VTOL Tailsitter which would use only the DX9's incredible programmability and a Lemon Stab+ receiver, cheap HK servos and a couple of sheets of Elmers foamboard. Stabilization and self-levelling were available, and although I tested each briefly, neither was otherwise employed.

I got a lot of flight experience and several more ideas from this flight. My Mk.1 version also flew without incident; however, I was not satisfied with a couple of aspects of its design and handling, so along came Mk.2.

In another, yet to come, video, I have some background on the project and demonstrate some of the technical aspects.

So, here it is:

https://youtu.be/FsS9Zsh-NR8
« Last Edit: August 16, 2017, 04:51:05 PM by Deerslayer »
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Online Dwayne

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Re: Tailsitter Mk.2 Test Flight #1
« Reply #1 on: July 19, 2017, 08:08:28 PM »
Hey that turned out really well,  ;D  Looking forward to see if you get it to land vertically, good job so far.  ;D ;D
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Online Deerslayer

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Re: Tailsitter Mk.2 Test Flight #1
« Reply #2 on: July 20, 2017, 03:54:04 AM »
Thanks, Dwayne, for your video work and your support. I am putting this project aside for a few days, thinking of the next steps and planning to try out my store-bought X-VERT tailsitter VTOL. Flypaper already has his under control ... sort of.

I have serious doubts about the vertical landing of my Tailsitter, as my brief try to hover at altitude was not very successful. Perhaps I will revert to the vectored motors approach of my Mk.1 plane. And, I have only used 9 of the 10 available mixes in the DX9, so who knows what is yet to be done!

Meanwhile, I found another homebrew design that makes more sense than mine, so I may shamelessly steal some of that fellow's ideas.
« Last Edit: August 16, 2017, 04:50:50 PM by Deerslayer »
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Online Deerslayer

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Re: Tailsitter Mk.2 Test Flight #1
« Reply #3 on: July 25, 2017, 04:23:10 AM »
This is the concept which attracted my attention:

https://youtu.be/9xjHCHR5_50

I have now flown my store-bought X-VERT a number of times, with vertical take-offs, transitions, full horizontal stabilized and unstabilized flights and vertical landings.

Now, back to my own Tailsitter!

I have decided to take a different approach to the VTOL modes. We are returning to vectoring the motors and eliminating the vectorons. This time, the motors will be vectorable to almost 90 degrees "up" and about 10 degrees down.
Takeoffs will be with the fuselage lying horizontally, motors vectored vertically to pull the nose up and lift the body, with transition then occurring rapidly by holding the motor thrust vector close to vertical while the fuselage rotates to inline with the motors and begins flying. This plane has the necessary much greater than 1:1 thrust to weight ratio. Landings would be the reverse of this procedure. Again, there will be no flight controller involved. I still have to resolve the issue of assymetric thrust, possibly due to motors not synching at intermediate portions of their range, resulting in hairy/scary launches.

Hopefully, testing will resume next week, along with video - disastrous or not!
« Last Edit: August 16, 2017, 04:50:25 PM by Deerslayer »
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Online Deerslayer

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Taildragger Mk.1 Test Flight #1
« Reply #4 on: August 10, 2017, 05:46:00 AM »
The testing continues, new learnings and some conclusions being developed.

The plane is now called Taildragger Mk.1, as it rests horizontally for launch, motors vectored about 45 degrees upward, ready to drag its butt vertically, then change to normal configuration. This actually works, as some others have discovered, and it forms the basis for my new project. The existing plane has been my training wheels, and I have learned a lot. I will leave tailsitting to things like my X-VERT and do VTOL in this manner.

 Two more test flights of Taildragger Mk.1 were done over the last couple of days. One was documented with video, which I may post sometime soon.

The first one was done with a hand launch, to sort out any trim issues and have some fun. This thing is an incredibly good flyer, very stable and yet will do some wicked unusual tricks. It will tumble around its horizontal axis if you enable Thrust Vectoring and then haul back on the Elevons. It will do some sort of flat spin, combined with tumbling and who knows what, if you start in slow level flight, pull up a little  bit, crank in full Rudder (differential thrust) hammer the Throttle and monkey around with the Elevons a touch. Yet, when you release everything, it comes back to normal flight.

Yesterday, I did a direct taildragger launch from the grass, It launched OK, but immediately swerved and whumped in. No damage to the motors, servos, etc., but it ripped off the one sponson. A few minutes with the Flypaper Welder, a.k.a. hot glue gin and it should be restored.

This was a successful test! Why? Because I learned something in that 1 or 2 seconds - something that has been at the heart of some difficulties on previous occasions. It is hard, or impossible, to nail the Throttle for launch without inadvertently introducing some differential thrust via the Rudder stick motion. Due to the way in which my system has to be set up (I use 8 Mixes to accomplish all that is required), I cannot implement Exponential on the Rudder function, so it is way too sensitive. Today, I will repair and have already set up a strategy of 3 Flight Modes. In the Launch and Landing FMs, the Rudder function will be disabled; it may or may not be enabled in Cruise Mode immediately after launch until just prior to landing.

I have also concluded that the Thrust Vectoring is too sensitive during Launching and Landing. Again, since this is mixed into Elevon functions (4 mixes required), there is no way to implement Exponential, As with the Rudder function, I want/need full Travel on those channels. So, I have implemented another way to calm things down, one which might be of use to folks who love the play with Flaps. Many are unaware that on the DX9 and many other radios, you can set Servo Speed. I played with different values for the TV servos and am trying 1.0 to start with. So, when you crank in Elevons, theTV servos also respond but slower and therefore smoother. I like it!

So, hopefully one more kick at the cat (or is it the can? I forget), with this plane. Then it may be retired, as I need the hardware for the new Taildragger Mk.2 development. I plan to document the build of this very simple undertaking. Materials and construction are minor components, the real work has already been done and resides within the DX9.

The DX9 programming which is associated with this project is extensive and complex. It is well documented via spreadsheet. At least some of this would be an excellent starting point for someone who wants to try out a twin-engined aircraft of any type, not specifically a VTOL. I may even decide to post the SPM and the spreadsheet documentation.

« Last Edit: August 16, 2017, 04:51:51 PM by Deerslayer »
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Online Deerslayer

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Taildragger Mk.1 Test Flight #3
« Reply #5 on: August 15, 2017, 07:37:58 PM »
Well, Taildragger Test Flight #2 was somewhat brief and anticlamactic. No video, but I learned something, so we can call it ... Success!

This one was much better. The art of taildragging is a bit daunting, so I enlisted the help of Flypaper to provide an assisted launch. Meanwhile, Cal ran the camera. Thank you, fellows!

https://youtu.be/11auB5eNfZM
« Last Edit: August 16, 2017, 04:52:11 PM by Deerslayer »
My purpose in Life is to serve as a Warning to others