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Messages - Deerslayer

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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 / Re: Puddle Flying
« on: January 24, 2018, 03:24:39 PM »
Glad you enjoyed it! These are fun little machines. I flew mine today out at the field, sunny -8C, light breeze, warm stove in the club house. Perfect! Too bad no oneelse took advantage of it. Tomorrow looks good, too!

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:

Buy, Sell, Trade or Give Away / F-16 Ducted Fan Kits for Sale
« on: January 07, 2018, 07:35:53 AM »
I have two of these for sale. Dan and I had one a few years ago and can vouch for what a great plane these are. Hand-launched, easy to fly, they are a perfect way to try out electric ducted fan aircraft at a rock bottom cost. To my knowledge, these are no longer available, much to the dismay of the very large group of enthusiasts for the product.

Here is the primary RCGROUPS forum:

Many owners customize their F-16's in appearance and also with other than the original EDF gear - a lot has changed over the past decade. Some of these planes have been built with truly wicked performance packages!  The fan is readily available form Hobby King or elsewhere.

I am asking $45 each, and I would consider something slightly less if sold as a pair.

Plans, Projects, Building and Flying Tips / Re: Balancing Stuff
« on: December 26, 2017, 06:22:35 AM »
 Speaking of balancing stuff:

 As with a number of other aircraft I have designed and/or built, I often think up some different situations w.r.t. C of G concerns - before carving out material. For my new Penguin FPV plane, I decided to move the Elevator servo way back to the tail, rather than keeping it up front and having the long control rod. This is a common mod for the plane.

 Prior to the Penguin, I created a spreadsheet (available to anyone who asks) to investigate many configurations for a flying wing of my own design. I had flown it with a stabilizer for protection and determined where the C of G had to be in order for it to fly nicely, non-stabliized. In that case, I was about to add some FPV stuff onto the wing and needed to shift the LiPo sideways and rearward a bit to accomodate the camera, thus moving the C of G rearward unless I either added some nose weight (detestable!) or using, say, dual 1000 or 1300 mah batteries, or one 1800 mah battery rather than the single 2200 mah battery. There were a number of other possibilities.

 I ran the spreadsheet against about a dozen options and chose one of the best results. The plane flew as well as before the changes, with no parasitic weight addition. I have done this kind of paper work on balsa planes, where I wanted to achieve certain performance improvements (usually snappier!) without cutting into wood or stooping to adding weights somewhere.

 I may remove those atrocious nose weights from my Optera and compensate with larger or more LiPo, applying the same approach - measure twice, calculate, then cut once.

Now, for the Penguin example:

Required C of G location is the datum (everything measured from there)
Servo Weight = 20 grams
Standard Location = 10 cm aft of C of G, approximately (distance from datum to middle of servo)

Rear Servo Location = 65 cm aft of C of G (conservative estimate, could be slightly less)

Required Counterweight Location = 35 cm forward (conservative estimate, could be slightly more, your choice)

a) Initial Servo Moment Arm = 20*10 = 200 g-cm

b) Rear Servo Moment arm = 20*65 = 1300 g-cm

Moving of Servo from Standard to Rear Location: 200 - 1300 ~ -1100 g-cm required to compensate
Therefore, required Counterweight at 35 cm forward: 1100/35 ~ 32 grams

For the Penguin, this much compensation is not a big deal, probably well within what I will instead do by battery selection and location. I have a large number of 2200 mah batteries, this being my personal upper limit for my electrikery inventory. I plan to parallel a couple - or possibly even 3 - of these for this plane. To fit the servo in its standard location, I would have to hog out the lasered hole a bit anyway. I hot glue servos into foam aircraft, so rear mounting is simple and I can still install a couple of CF strips if I am really concerned about strength. Of course, my landings are always as soft as settling onto a pillow anyway

Plans, Projects, Building and Flying Tips / Re: Balancing Stuff
« on: December 19, 2017, 09:26:47 AM »
I check the balance of every prop I buy, over the years that's hundreds of props and have only found a handful that balanced as bought, I find Xoar to be the best followed by APC, some of the worst are Master Airscrew, I had a 11X6 that was so bad I had to cut almost an 1/8th inch off one end and add a bunch of CA on the So it's always good to check em. 

Never heard of balancing  a motor seems a bit over the  :P :laugh:

As for balancing props: I carry a heavy load of guilt for my slovenly practices! XOAR and APC have reputations as good as it gets. Some of the knock-offs and el cheapos are pretty poor for balance was well as being of poor efficiency, from what I have read.

As for balancing motors: I agree, it does seem excessive. The context was that the author is trying to make his FPV work as smooth as possible. That has, so far, been the least of my concerns, as all of the little variances and movements probably make any motor imbalance to be relatively insignificant. However, it is an interesting exercise, especially if you have a smart phone and are looking for entertainment other than watching cute cat videos!

Plans, Projects, Building and Flying Tips / Balancing Stuff
« on: December 14, 2017, 11:35:19 AM »
At least some folks make an effort to balance their props. Others just trust that things are OK as bought - count me in that sorry lot! I use APC props exclusively, unless something else was provided with the airplane I bought. I find them to be very high quality and well balanced. I have had a little, relatively unused, balancer thingy lying around in my flight box for "about a hundred years" (a FlyPaperism). Then, a couple of years ago I sprung for a more expensive and capable unit. Well, I had paid for it so I just had to try it on several of my APC props; I never could determine that I needed to do anything to improve them. Meanwhile, I got the Crack Beaver and its somewhat unusual props. When I checked them, they needed a LOT of balancing! So, perhaps buying the balancer was worthwhile, after all?

What about balancing electric motors? What about the balance of the whole motor+adapter+prop assembly? Well, I came across this very interesting article. He uses an iPhone app to do this. I have an Android tablet and phone, but, there are several apps available for Android which can do vibration or seismic analysis.

I hope someone else finds this interesting and perhaps even useful:

FPV at KRCM / Simple Pan/Tilt System and Fun Cub
« on: December 12, 2017, 11:16:41 AM »
Well, there are few more versatile planes than the Fun Cub to do everything from learn the basics of r/c flying, aerobatics, land/snow/slush/water flying, messing around with various mixes and just having fun. I use mine as a test bed to try out various ideas, especially more complicated things like multiple Flight Modes and mixes, sometimes transplanting the results over to my sailplanes or other aircraft.

So, along comes FPV (for me. a bit late to the game!) Having tried Mobius-based video work on various platforms, including the Fun Cub, Skipper, a couple of my deltas, the Optera and the Black Widow wing, I figured FPV was overdue to try. I did so, on a couple of that above-mentioned planes but, having seen Wilf's progress, I decided to move along to a FPV-specific plane.

Meanwhile, the Fun Cub was the place to try FPV, and my Tilt/Pan setup. Great success! The Cub proved to be an ideal platform - rock solid, slow flyer, no sudden stall/spin tendencies and very flexible landing gear. I have had a number of complete flights under the hood (Headplay goggles), using the Foxeer camera on my mounting system and the 5.8GHz video transmitter. It practically takes off and lands by itself.

The physical arrangement for the FPV camera + Tx is a replacement Cub canopy I made from balsa. Having already used 7 channels in this plane, I plunked in a Lemon 10-channel DSM2 receiver, as I needed 2 more channels. In hindsight, an 8-channel would do, as I have not found the Tilt function to be of any real use; however, I haven't had much time to play with this stuff, so you never know.

In addition to other Flight Modes and mixes I already have on the Fun Cub. I set up 2 switches associated with the Pan function. I like to mimic what would take place in a real airplane, i.e., what does a pilot do during taxi, takeoff and normal flight and landings. The Pan and Tilt servos are set to a slightly slower than standard speed, to provide nice smooth movements (which also avoids the tendency to cause vertigo!)

As I am taxiing, Pan is enabled and coupled to Rudder, so that the pilot can look around for situational awareness and avoidance of obstacles. The amount of mixing is around 20%, as you just need to look around normally and the camera is quite wide angle. As well, at any time and in any Flight Mode, I can pan via the knob on the DX9. 

At any time, normally in the air, I can switch in coupling of Pan to Aileron. It is mixed perhaps 20% to Aileron. The result is similar to what a pilot in a real aircraft does, i.e., shift one's vision to the direction they are beginning to turn, returning to straight forward once the turn is established.

Note that, if one left both Rudder and Aileron coupling to Pan, a properly coordinated turn entry would result in the 2 commands to Pan being additive. That could be helpful to know, and to utilize.

I haven't done much with Tilt. It is assigned to the Right Auxiliary Trim lever. I suppose one might want to mix it into Elevator during certain aerobatic maneouvers. For instance, in a real aircraft, during a loop you may tend to raise your vision toward the inside of the loop, lower it to normal at the top as you relax the stick and then again raise your vision toward the top of the canopy as you pull through the last half of the loop. (I have done may loops in real sailplanes and it is easy to think through what you are doing in real time; things happen much quicker with models!) If you are thermalling, you do tend to look around and up/down a fair bit, especially if there are other aircraft in close proximity and/or or soaring birds available to point out good lift.

This stuff is great fun. My original plan was to try it out on the Fun Cub and then transplant the FPV gear to the newly acquired Penguin FPV plane. Now, I have had second thoughts and plan to leave the Fun Cub fully geared up and buy a second setup for the Penguin.

If I want to do video recording on the Fun Cub, the FPV setup could do it. However, there are 2 issues: the FPV camera sees the prop, which makes for messy video work; the video recording would take place via the ground station, which results in a noticeably degraded result, compared to the in-camera recording. The solution here is to once again mount the Mobius out on the Fun Cub wing, which works perfectly to solve both problems.

The ideal FPV aircraft, as I see it, is a pusher. The Bixler (Roger's machine), the FliteTest plane that Wilf built, the Sky Mule twin that Wilf now has, the Penguin, or any of several other popular designs work well. The possibilities are endless!

General Discussion / Bulk Orders
« on: December 11, 2017, 08:54:53 AM »
Occasionally, two or more flyers get together to order items from places such as Hobby King, Banggood, etc. It can get a bit messy estimating what it all may cost and later on, sorting out who owes exactly what. Attached is a spreadsheet that I created and offer to anyone else to use. 

Caveat! Although it has been thoroughly tested and I trust it, I cannot guarantee it. If you use it, check the results carefully to ensure that it is correct. This is a tool, not a replacement for your own judgement. If you find a problem, please Reply in here so that I may correct it.


1. Download the attachment. I use OpenOffice and have saved it in as an older Excel file, so it should be readable by any spreadsheet package. If not, let me know and I can provide other versions.

2. Play around with it.
 The cells marked in RED are available for you to fill out. If your order is priced in CA$, leave the Exchange Rate as 1.0 and enter the Item Costs under the US$ -  everything ends up in CA$ anyway. If it is a USA order, set the exchange rate, e.g., .71 on a recent order I processed.
 Leave the BLACK cells alone. The one exception may be under the Shipping/Handling distribution. For example, one fellow orders a kit, or perhaps some LiPos, while another one or more just order some servos or other small stuff. I would divide the  Shipping/Handling
total charges in a fair manner and place those amounts into those cells.

3. If you have played around with this Template, make sure you do not Save it, else some future use may result in a garbage result due to an item or formula having been modified.

 If there are more Items or Buyers than have been set up on this sheet, it could be modified - very carefully! Perhaps it would be better to simply start a second sheet to handle the excess Items or Buyers. Then you divide the Brokerage, GST/HST and Shipping/Handling charges between the two sheets.

 Sometimes, I think that I might want to order something from Supplier X, but do not need it right away or would like to combine my items with someone else. I go to that site and add my stuff to my "Cart", then leave the site. Yes, I will likely get pestered once or twice that I have an incomplete order. I just ignore that, for now. Later on, another person(s) wants something and we decide to place a bulk order. I encourage him/them to do the same thing, i.e., stock up his/their "Cart". Then, if he/they can scrape out and email me a copy, I can go to my "Cart", add his/their stuff, get the estimated Shipping Charges, etc. and transpose the details to the spreadsheet. When we all agree,
I process the order. Upon delivery, I check and update the spreadsheet to reflect the final Exchange Rate, Taxes, etc. 

Plans, Projects, Building and Flying Tips / Re: Fokker DVIII Build (update)
« on: December 10, 2017, 08:48:59 PM »
Thanks Gary.
Ok I'm going to share a little secret passed down to me by an old photographer type guy. When shooting pics of your builds, move the junk so it's no in the shot.  :laugh: :P ;D 8)
That's easy for you to say - I would have to shove my stuff out the door and into Lake Ontario!

Plans, Projects, Building and Flying Tips / Re: Fokker DVIII Build (update)
« on: December 10, 2017, 12:18:30 PM »
Good work D. Nice too see someone actually building with balsa and fabric. This will be a nice airplane, for sure. I have seen the full scale replica fly at Rhinebeck and it is an amazingly fast, quick to maneuver and sharp looking machine.

BTW, how do you keep such a neat work area?

General Discussion / Re: Servos - how they work
« on: December 06, 2017, 12:14:07 PM »
In my experience, it is almost always the second gear from the top. They tend to split when over-torqued. There may also be other gears with damage. Sometimes, this is from the initial breakage up top, with teeth getting jammed into other gears. I, too, have an extensive collection of unuused gears! As a mechanical engineer, I cannot bear to throw out some of Man's greatest products; they are bound to come in useful someday, right?
This is another good insight into how servos work. In particular, starting at around  the 4:20 mark, you will see the typical damage that I usually encounter. On my Heron, very poor quality connectors from Multiplex were eventually found to have caused thrashing and subsequent damage to several servos. The servos would be driven rapidly onto their internal mechanical stops, splitting the second gear and grinding other gears with the broken teeth.

I found HiTec gears at Leading Edge. A set usually costs a significant fraction of a new servo but it is still worth fixing. HK gearsets for the XT900 cost less than a buck - of course, the whole servo costs only about $3.

Sometimes you run into an unusual servo, such as the red "Tiny" ones on my Multiplex Heron. I discovered that they are HiTec, so LE has replacement gearsets for about $6. Until you get into really large and expensive servos, most likely they all come out of the same one or two factories.

 Nylon gears really require little or no lubrication. I give the assembly a quick shot of my DuPont lube with Teflon (available at Lowes), but just about anything will do the job.

General Discussion / Servos - how they work
« on: December 06, 2017, 06:34:27 AM »
Here is an excellent and easy to understand video that shows what goes on inside that tiny electronics package in every servo. There are other videos that depict the mechanical actions. Sometime, grab an old servo and pull it apart to see for yourself. I have repaired many servos, as most likely cause of problems is gear damage due to binding or otherwise overstressing the system; for most servos, from the cheap Hextronic ones through to the most expensive, you can buy the gear train and spend a few minutes to restore one to new (sometimes better than new!) condition.

The attached document was prepared by the Zone Director and Club Presidents.

Buy, Sell, Trade or Give Away / Re: Electric Foamies and gear for sale
« on: December 02, 2017, 09:15:40 AM »
Any idea what the Parkzone foamie is?
Why are you up so early.
Note that my airbrush ad now has a price on it, somehow I missed that.Is there any way to contact the people that viewed the ad?

Parkzone foamie - I don't know what it is, suggest you  call him.
I am always up early - somtimes 0400, more often 0500, occasionally sleep in until 0530! (In my working days, I struggled to get up by 0700, scramble around and get in to work by 0730 - what a life!)
There is no way to tell who has read something. I suggest that you put a Reply in to announce the price.

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