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Topics - Deerslayer

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I have owned the DX9 for about a hundred years (as my late friend Flypaper would say!) and am still discovering what certain things do and can be used for. Here is one situation that presented and which a simple combination of Flight Modes and Digital Switch Setup functions provided the solution. This is applicable to any of the DX-series, later generations of transmitters, which run the common Airware operating system.

The problem was, the Vector flight controller/stabilizer in my plane has a large selection of Modes. You can select up to 5 Vector modes (not to be confused with Flight Modes, which pertains only to the transmitter setup.). These can be assigned to one or more switches, commanding a specific channel which is connected from the receiver to the Vector.
Setting up 3 conditions on a 3-position switch is easy, but I wanted to use 6 position across two of my switches. As well, I wanted settings of these two switches to be mutually exclusive.

First, you need to understand the Vector's Mode protocol. They look at the Mode channel and enable 1 of the 5 possible Modes depending upon what is the pulse length. Don't worry about how you figure out how to convert Pulse width to the % values the transmitter shows, I will explain it later on.
Here is the table showing which Mode the Vector is in, as determined by the Pulse width
1 < 1250 microseconds
2 1250 - 1400
3 1400 - 1600
4 1600 - 1750
5 > 1750

Now, a word about Flight Modes. I have a very simple set of Flight Modes for this aircraft - only 3, so it only requires one 3-position switch. they are 1,2 an 3, which I call Normal, Cruise and TO/GA (takeoff/go around). Certain control mixes may, or may not, be enabled when each Flight Mode is selected. When I establish the Mixes for my two 3-position Vector Mode switches, I select which Flight Mode(s) will enable that switch and, therefore, the 3 Vector Mode settings allowable within that Flight Mode.

I use the GEAR channel for my Vector Mode. As with all my aircraft, a Channel Assign moved control of that channel away from the default A switch, as that is my Throttle Cut; I assigned the Gear channel to the F switch.

Now, I have already created the 3 Flight Modes, so it is time to set up the Mixes. 
1 = Normal   No Controls mixing
2 = Cruise    No Controls mixing
3 = TO/GA   Lots of Controls Mixing (for Crow, etc.)

Next, comes the Digital Switch Setup. Digital 2-position and 3-position Switches by default have  +100, 0, -100% as their command outputs, Digital Switch Setup allows you to change each of these individual positions to anything from 0 to 150%. I want my switches to operate in the Normal and Cruise Flight Modes, as follows:

Switch E -
Pos 0  = Vector Mode 1 = Loiter
Pos 2  = Vector Mode 2 = 3D Heading Hold
Pos 3  = Vector Mode 3 = OFF
Switch F -
Pos 5  = Vector Mode 5 = RTH TEST
Pos 4  = Vector Mode 4 = 2D Heading Hold
Pos 3  = Vector Mode 3= OFF

So, within the Digital Switch Setup, I have set Switch E to have 0, -45 , -100 as its three positions and Switch F as 0, 45,100 as its states. (I have already translated the requires Pulse widths to determine the +-45% settings.

Then, we set up two simple Mixes:

Switch E is mixed to GEAR  with its default 100,100 values,  active in Flight Modes 1 (Normal) and 2 (Cruise), disabled in 3 (TO/GA).

Switch F is also mixed to GEAR exactly as with Switch E.

Now, in either the Normal or Cruise Flight Modes with both Vector Mode (E & F) Switches in the Down position, the Gear channel is outputting  the "0" or Centered command, so the Vector is in its OFF Mode. In TO/GA Flight Mode, these two Switched are inoperative and the Vector is in OFF. This means that, at any time, pulling both E and F back will turn the Vector OFF, regardless of Flight Mode.

This is simpler than it may sound. This particular need and the specific settings of Switches is just one example of what can be done with two very powerful functions on Spektrum and other systems, once you get the basic idea. I have done a lot of Mixing, etc. across many aircraft of different types and with varying setups, yet I am still learning new stuff all the time.

If this gives anyone some ideas or questions, please let me know. I may be able to help you, or at least point you in the direction of someone who knows a lot more about it and is very patient and willing to assist.


Addendum - Translating % to Pulse Width

Spektrum defaults to Pulse Width range of 900 to 1900 as -100% and +100%, respectively.  You can set Servo Travel to as high and low as -150% and 150%, respectively. Pulse Width = 1500 is 0%, or Center, regardless of the range setting. For my Vector control example, I Ieft them at the defaults.

My test setup consists of a receiver, digital servo tester and servo attached to a degree wheel. The latter is just for interest, only the receiver and digital readout on the servo tester is required. For this test, and in the eventual aircraft setup, make sure that there is no unwanted Mix or Trim settings lurking in the background to interfere with your required operation. (Experience speaking here!)

Pulse Width = 1500 is 0%, or Center, regardless of the range setting.

I set up my test channel such that it was on the Throttle, as that enables more precise adjustments which stay in place while taking various readings. In the Trims menu, I had set Throttle Trim to "0", to ensure that I got clean readings, with only the stick movement. From there on, it is simple:

1. Go to the Monitor screen on the transmitter.

2. Set the throttle stick in various positions, taking readings of both the % on the transmitter and the Pulse Width microseconds on the servo tester. If you are really interested, as I was, plot them and convince yourself that they are linear, and/or  have your servo degree wheel hooked up and watch it wiggle around. Do not worry if the digital readout is slightly different from expected; mine read 17 microseconds high at the Center and the endpoints, I do not know why, but it is a trivial error.

3. My Vector modes required it seeing the following Pulse Widths:
1 < 1250 microseconds
2 1250 - 1400
3 1400 - 1600
4 1600 - 1750
5 > 1750
So, via Digital Switch Setup, I set Switches E and F to have "0" at their same position, pulled fully back. That gives Mode 3 on both.
Then, I set Switches E an F to be at -100 and +100, respectively, in their furthest forward positions. Modes 1 and 5 are now taken care of.
Mode 2 and 4 are the ones where you need to know the correspondence between % and Pulse Width, as these activate within narrow ranges of values. I found that +-45% values were fairly centered within these required values, so those will be the Switch midle positions.

Therefore, my Digital Switches are set up as E = 0, -50, -100 and F = 0, 50, 100.

The servo tester with a digital readout is my most valuable gadget in the shop or at the field. This is one example where it was essential. I use it to check out every new servo immediately after purchase and every servo prior to, and immediately after, installation in an aircraft, or when a malfunction occurs or is suspected. Get one for yourself!

FPV at KRCM / Some FPV Ramblings
« on: April 14, 2018, 11:36:18 AM »
Attached is a summary of some FPV-related stuff I have been doing. I hope it give someone some ideas, or can start a discussion.

It surprises me that Flypaper never showed up with one of these ... or did he?

VIDEOS and PICTURES from KRCM Events and Activities / Levin's Hotts
« on: April 12, 2018, 08:38:46 AM »
Harold and Levin have been at it again! They dug out what is claimed to be a Hotts sport airplane from way back in time, cleaned it up and fitted a new ASP .46 engine.

Back some 30 years ago, the Hotts was  at the top of the heap of fun flyers. Dan Santich designed the original one, followed by the Hotts II (two) and Midwest kitted it as one of their superb Success Series offerings. I had one of those and it was the most enjoyable kit I ever built, before or afterward. It was a terrific flyer and I would love to find on of those original kits to build again.

There were many variations of the Hotts that were created over the years, several of which even showed up in our Club. Giant scale, intermediate, biplane, SPAD, foamy, too many to recall.

This particular plane most be scratch built, as i has foam sheeted wings, no plywood sides or turtle deck and its fuselage shape differs from the angular slab facets of the original Hotts. The wing tips do not have the end plates which were very critical to taming the behaviour of the original Hotts II. But, who cares, let's call it a Hotts and see how it flies!

I was pleased to take it for the test flight. Wow! this thing really rocks and brings back some memories! After a quick try, I cranked in about 50% expo on the Ailerons and Elevator, eventually bumping it up to 60% on both after we did the second flight. We called it quits, as the wind was howling. I left Levin with a couple of suggestions, such as relocating the battery to move the C of G further back.

As this was the first flight for this plane and engine, in our hands, and it was a very windy and gusty day, I did the takeoff and the eventual landing. Levin took over in the air, once we got a bit familiar with it. He will have to be very careful, as it is a step change from the average airplane that scoots around these days but he is very capable of handing it. 

Some of you may know Levin, a.k.a. Flight Kid.

Apart from hanging out with us and flying, he leads a very challenging academic life. Recently, he participated in the regional Science Fair at Duncan Macarthur Hall.

Harold and I were privileged to obtain a sit-down VIP visit with Levin at his display. We were unable to stump him with our questions; he really does know what he is talking about!

Levin's project was the laser CNC system which he designed, built, programmed and documented. His dad helped with the cutting of the wooden components and perhaps in the de-bugging associated electronics, but L learned/utilized the GRBL programming language and all of the other associated technological aspects. The device works, although he was not allowed to activate the laser at the Fair, due to safety requirements, quite understandable, even though he currently has only a 5mw or such laser from a CD drive. He plans to purchase a higher powered laser and be able to cut foam for ... guess what ... flying machines!

I suggested that he bring his travelling road show out the to field sometime this summer (perhaps at the FDFF) and display it.

Harold and I were really impressed with the tremendous efforts and variety of projects at the Science Fair. We walked away feeling really positive about those who will be the future Engineers and Scientists and leaders. Great work and Good Luck to all of them!

Perhaps our guy will choose to comment in here, with more explanation, if he ever gets some time!

Meanwhile, here are a few pictures taken at the event.

Well, guess what I found out at the Toyground! (Pictures attached.)
Grasscutter was rootin' around with a digger that he "borrowed" from ... don't ask! So, what is he up to? Well, he started out strip-mining an area just east of the building (there is only one building now). He seems to have hit bedrock before encountering any gold or human remains.

You never saw a guy so happy as this fellow playing around in the dirt. By the way, who would have guessed that there is actually some high quality soil between the grass roots and the rock around here? Look at the giant pile!

His next step was to call in a load of crushed stone and start filling the hole up again.

So, what is he really up to?

This is the first step of expanding the dining/observing area. A concrete pad will be poured and, if the money doesn't run out, the clubhouse overhang will be extended over it.

This will provide a very nice shelter for the Peanut Gallery, as well as a place to set up or work on planes, as well as to prepare food and eat it.

KRCM owes Marvin a hearty thanks for scrounging up the excavation equipment and knowing how to use it.

As I was leaving, Mike was on his way out with a surveyor's level so that Marvin could begin the levelling and tamping of the stone. (It looked to me that a couple more loads would be needed to establish the base for the 5 inches of concrete to cap it off, so he may be at this for awhile yet.)

Marvin - how about an update?

General Discussion / Classic Canadian Test Pilot Documentary
« on: April 05, 2018, 07:15:26 AM »
This is a superb film, produced by the National Film Board with Fred Davis as the reporter. Some may recall Fred from his days as host of Front Page Challenge. DeHaviland's chief test pilot is featured. It is hard to realize that some of the air work overlooks the farmland area way out at Downsview (it was sort of Canada's Area 51)! In the segment on the water, you can pick out the old Five Roses (I think it was) grain elevator and the Toronto Island ferry scooting across the harbour. Some of us can, at least dimly, remember seeing some of these state of the art aircraft at places like the old Trenton Air Show. Fine viewing, hope you enjoy it!

I have had bad experience over many years with various connectors and their installed wiring. The pins may pull fullu or partially out or the wire may break at the pin, usually after significant use but sometimes right from the manufacturer.
This is a real problem with some FPV camera cabling, where they use extremely small connectors and wire and the assembly may well be subjected to constant buffeting by an airflow.

What I have been doing for some time, is to use some of the red RTV and force it into the end where the wires exit and out a little way onto and through the wire bundle. If you have trouble getting a neat looking job, just lick your finger tip and lightly smear the RTV, as it is a silicone and will smooth out without sticking to your finger.

After overnight drying, this makes an excellent strain relief. I also use further support for cabling, especially these really stiff yet delicate ones which may be exposed to handling and air turbulence.

I often use pipe short pieces of pipe cleaners, one end or the center of a short piece hot glued to a structure and the open end wrapped a turn or two around the cable(s). Easy to set up, looks neat, easy to undo and redo, if required. At $Tree, they have packages containing a lifetime supply (unless you are a pipe smoker, I suppose, but then you may have a shorter life anyway?). They are packaged in several colors, so you can even code certain wires or bundles if you wish. Also, these can be handy to code LiPos (Red = needs charging, 2 Reds = suspected bad cell, etc., Yellow = in storage, Green = good to go).


In Canada, these are sold through Marks. I picked up a couple this winter, CDN$10 each, intending to use them as hand warmers while flying. They have lots of other uses.

One possibility would be to use as a flight pack on glow or gas plane. You will have a 5.5 volt, 2000 mah lightweight power source. All that is needed it to grab a USB cable, chop off the appropriate end and install suitable servo connector to attach to your receiver, etc. As for recharging, any USB charger will work. This unit has an LED that shows if and when it is charging and will terminate the process at the proper time.
If you fly in winter, you could even put one or two of these in a LiPo pouch to keep some batteries warm and/or to prevent your field charger (such as a Cellpro) from going into "Cold Weather" charging mode instead of fully loading your LiPos.
I got caught with a low charge on my Mobius FPV camera one day out at thefield, but just plugged it into one of these and was back in business awhile later.

It's a nice later Winter (or is it Spring?) day, I have the field all to myself, a great fire in the stove, it's time to play around with a bunch of my flying machines.

Meanwhile, the (Signals Corps?) have been encamped over on the DoD property for several days now, with a large tent and some vehicles sprouting rather interesting looking antennas. So, as part of my flying activities, I did some reconnoitering (fancy term for spying!) of the area.

The Crack Beaver is a light, high performance/wild 3D machine - not the first choice for FPV, but it was begging to have a little go at it anyway. Well, here is a brief video depicting my setup from both aerial and ground viewpoints.

FPV at KRCM / Head Tracker - Part 1
« on: February 24, 2018, 07:23:17 AM »
Where's your head at, Boy!?

Haven't we all heard that? Well, some of us may have, perhaps on more than one occasion!

Wilf and I bought HeadTracker modules from SmartFPV. These units originally were designed by Dennis Frie and have a complete DIY writeup  and a very popular forum in rcgroups. This  company has prompt and efficient tech support, a real bonus for some of us.

We are learning and experimenting now. What is this and how does it work?

The module contains accelerometers and magnetometers for the three axes. These are monitored by an Arduino. Its output is a PCM pulse train that provides commands to up to 3 channels within the stream that will eventually emerge from the rc transmitter.

The unit is cabled to the Trainer port on the Tx. Whenever you select the Student mode via a switch, the HT is in control of whichever channel(s) you had selected. If you de-select, the affected  channel(s) are immediately returned to neutral and control is relinquished to the Tx.

So, the idea is to mount the HT on the FPV goggles or helmet. Then, you connect your aircraft's camera moving servos to one or more channels - normally, for Pan and possibly for Tilt, although Roll may be of use in some situations. 

When head tracking is enabled, the camera will follow your head movements. It's that simple. You get more of the feel of actually being in thr aircraft while flying, as well as being able to do ground ground obstacle checks while taxiing under the hood. Nice,

Well, there can be a lot more to it, but that gets us started!

Meanwhile, I have another HT on order, to serve as a spare as well as for another, unconventional use of thr technology, or perhaps to pass along to someone else who may become interested in trying out this stuff. I will put a little writeup in here as my "secret project" progresses, warts and all.

General Discussion / REAL Indoor flying!
« on: February 21, 2018, 10:53:18 AM »
Everyone that hangs around our Toyground knows the local masterful Circle Flyer. His name starts with a "D" and has a "Wayne" in it (perhaps that is his alter ego?). Unfortunately, the poor fellow has an actual job, so he cannot come out and play as often as some of us n'er-do-wells. We have often wondered how he keeps his tenuous grip on sanity.

 Well, here is one possibility! Perhaps we can get an invite to slide on over to his house, have some beers and watch how he keeps in practice?

General Discussion / Real Indoor Flying!
« on: February 04, 2018, 09:18:40 AM »
This is one of the best examples of indoor flying. Note, all that is required is a standard sized basketball court and some really great ideas:

This is a copy of the posting I made in another Forum, where the BGL-6G-AP GPS-capable stabilization system is discussed, Wilf and I have these units and have done a lot of experimentation with them.  Don't worry, there really is a video in here, at the end of the discussion.  :D


This may be of interest to others:

I have had the unit on a flying wing for a couple of months, as a test bed. Yesterday, we were flying in extreme winds - significant wind gradient plus high level of turbulence. (Don't worry, there is a Video link at the end of this).

I set the plane out a somewhat downwind and the selected RTH. It immediately oriented itself and then flew upwind toward the Home point, as expected. I had, let's say, 1/3 throttle to maintain good progress.

Aside: the BGL's Return To Home control strategy is to self-level if necessary, head straight back to its Home coordinate, then circle or sometimes follow a figure-8 pattern centered on Home. It will attempt to maintain a constant altitude, provided it can maintain airspeed; if you chop the throttle, or are a pure sailplane, it will gradually lose altitude and may even stall or perhaps snag a nasty tree or such before you may regain control.

The plane arrived in the vicinity of Home and began its circle. Now, as one would expect, there will be some drifting and the resultant path over the ground would be somewhat elliptical. However, to the airborne pilot, maintaining a constant bank and airspeed will still result in a circle within the air mass. Now, one would expect the RTH function to be trying to maintain a circle with respect to the ground, as it is using the fixed Home coordinates and its GPS to set up a fixed radius circular or figure-8 pattern w.r.t. that ground Home point. Therefore, I expected to see it altering its bank angle accordingly, within limits, to try to retain its circular orbit. Not so much!

With this strong wind, the plane made its first turn and flew WAY downwind before beginning to turn back to Home. For awhile, I could observe it making some control corrections, probably experiencing some turbulence even at its "3 trees" altitude. I really began to wonder if something had gone wrong, but it eventually managed to turn back and beat its way toward Home. I had been just about ready to switch off RTH and take over with full throttle in order to get back. Well, she did make it back without my interference, but I had to use a high throttle and I watched as it sort of zig-zagged along its path back.

I repeated this test, with exactly the same results.

Now, this was a bit disturbing, but it was a good learning experience.

The BGL limits its bank angle to something that would be a shallow to medium turn while in RTH, regardless of its reference to the Home coordinate.

So, if I have this unit installed in, say, a sailplane that may not have terrific penetration and if I were to lose sight of it, I better crank up the motor and hope! As we know, you normally thermal in a circle within the rising air mass which, in turn, is being shifted downwind. Think of a funnel that is tilted and you are keeping inside of it. As you go higher, the migration downwind is likely to increase, as will be the effort to beat back home once you leave said thermal, especially when you encounter the surrounding sinking air.

In considering using the RTH feature under Failsafe, the question is, does one kill the power or set it to something like, say, 1/2 throttle? Not an easy answer, as circumstances vary. Besides, you may have no choice anyway! Not all receivers handle a loss of signal the same way. and ESC's tend to shut off the throttle if no signal is seen for a very few seconds. So, all you can do is hope for the best! Also, you may want to bump up the throttle immediately upon activating RTH, if you cannot see the aircraft or if you suspect that it may have failed safe into that mode. If you in no-power soaring mode and go into RTH, the aircraft may not make it back, especially if it has to do much banking to achieve a straight line flight path and/or if it does a lot of the weaving back and forth that I observed. Of course, you want to know that your airframe, especially a large foam sailplane, can stand high airspeed and gust loading combined, or it may relocate itself in pieces!

I think about this stuff. It's all part of this weird hobby. We have so much terrific technology available, it is fun to learn what it can, and can't, do.


General Discussion / Vortex Generators
« on: January 08, 2018, 10:56:41 AM »
Vortex Generators (VGs) have been around for many decades. I first noticed them on airliners I flew on back around 1970. You may notice them on smaller airplanes, especially of the STOL variety such as some bush planes.

About four years ago, my son started flying a Cessna 206 floatplane for his client. He installed a VG kit on it. The kit was a properly engineered and certified modification, cost $2500, which he installed over the course of a day or so. There was some huge number of these things, epoxied onto the top of the wings and onto the underside of the horizontal stabilizer. Their effect was to improve airflow separation over these surfaces. This resulted in approximately 5 knots lower stall speed or could allow a higher payload capacity. Floatplanes often have to squeak into, or hop out of, very confined areas with nasty trees, etc., in close proximity. The VGs were the one thing that could be done to improve things.

At that time, I became interested in finding out the science of VGs and how their effects are investigated and quantified. The information is out there, and there is fluid dynamics math, but some of it left me a bit bewildered.  I like pictures and videos! (Be patient, there is one coming up shortly...)

More recently, VGs started showing up on RC models. The Visionaire, Carbon Z Cub, Scimitar, all of which I have owned, are just a few that come to mind. Do they work at this small scale and low Reynolds Numbers? Hard to quantify, but experienced pilots report that they do make a difference, at least on some airfoil and airframe configurations.

I found this video to be enlightening. The fellow is admittedly not an aeronautical engineer or fluid dynamicist but he has done a terrific job of explaining things and documenting his experiments. The RC plane test near the end is a particularly compelling argument to accept the value of VGs and not just grab the Exacto knife and slice them off (as some amongst us may have done in the past!).

So, please sit back and check out this:

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