JD-Slow-Thumbs's blog View Details
Posted by JD-Slow-Thumbs | Mar 07, 2019 @ 06:57 PM | 1,982 Views
I think I found a wind-tunnel, a BIG wind-tunnel.
I was trying to figure out how to setup and document a KF-airfoil experiment tied to the front of my car without something breaking lose and breaking my windshield. Then I thought about indoor skydiving. Looked on Google-Maps for any indoor skydiving places near me in Los Angeles. Decided to investigate the iFLY Ontario. I talked to one of the managers and one of the instructors and instead of shutting me down they seemed receptive to my ideas. Like I said, I think I found a BIG wind-tunnel.

and their locator map shows 36 locations in the USA
and the Ontario (Los Angeles) location looks about like this.

Now I am trying to design experiments that don’t cost a lot of time/money

Thanks for reading
Posted by JD-Slow-Thumbs | Apr 08, 2018 @ 11:32 PM | 2,438 Views
Another discussion about the AMA as a CBO and can the FAA require membership. Many/most people are saying that the government can not endorse a club and require membership in order to fly R/C aircraft. I agree, that the FAA can not require AMA membership, but for different reasons.

Can the government require membership in a professional association?
Most of the time – No.
Sometimes – Yes.
I am thinking of Medical Doctors, Attorneys, and Realtors. In these three examples of professional associations, there is an agreed upon body-of-knowledge, a certification-exam endorsed by the state/federal government, and a “code-of-ethics” that must be agreed to. About ten years ago I remember reading about a Realtor that had her license revoked by the state because she violated the “code-of-ethics” by discounting the customary commission. (No longer applicable in most states, I hope).

Fast-forward to these discussions regarding AMA as CBO.
I see wishful thinking on the part of the FAA wishing that the AMA could agree on a body-of-knowledge, and a certification-exam, and a code-of-ethics (safety-code), and some enforcement. The AMA has a safety-code. Well, one out of three aint bad Personally, I see the Part-107-License as the trend of the future.

Hope to keep on flying.

The discussion is over here.
Posted by JD-Slow-Thumbs | Mar 27, 2018 @ 10:05 PM | 2,742 Views
There has been several discussions/threads about the AMA (Academy of Model Aeronautics) effectiveness as a CBO (Community Based Organization) and lobbyist trying to protect the R/C Airplane hobby. The general consensus is that they are not effective and people are discussing why not. I finally added to one of the threads.


The inability to tell people "NO" is why Washington doesn't pay attention to the AMA.

Is the AMA a CBO worth inviting to ... important meetings where future paths are decided?

Well ... I think back to the B-29 crash at "Wings-Over-Delaware-2014".
(Apparently one of the four engines stuck in idle, and things went bad in "R/C-Time").
Along with the usual questions about could the pilot have detected the engine malfunction sooner, was the plane capable of being steered away from the spectators, decision to go airborne, etc...

There were also questions about, was the runway too close to the line of spectators, was the fence/netting strong enough to stop a runaway B-29?

At the AMA-EXPO in January 2015, I saw an AMA representative giving a speech to regional and club Safety-Officers and cornered him after his speech. I asked if the AMA could tell (force) a club to follow guidelines for distance-to-runway, or inspect an aircraft, or have a pilot demonstrate proficiency with emergency procedures, or ground a pilot who had crashed three...Continue Reading
Posted by JD-Slow-Thumbs | Jan 27, 2018 @ 12:38 AM | 4,485 Views
I made a simplified Helicopter Collective for use with flight simulators like MS-FSX. I made it by splicing into a joystick. Works pretty good.

Thanks for reading, thanks for watching

Collective BuildLog 3B2 – on YouTube
Collective BuildLog 3B2 (5 min 9 sec)

Posted by JD-Slow-Thumbs | Aug 20, 2017 @ 06:42 PM | 3,529 Views
The other night I was browsing the forums and a title caught my eye,
Depth perception problems and eye tests, by BernardW,
I replied with the following:
About “Depth-Perception” at longer distances.

Binocular (two-eye) vision is great for things that we can hold in our hands, ok out to about three meters, poor at six meters, and not worth much at all at fifty meters.

Probably the biggest clue about distance is knowing its’ size and seeing “how big” it looks off in the distance. (At a distance "how-big" would be a small angle).

Other major clues are its’ relation to foreground and background. When it passes in-front-of a tree we know it is closer, when it passes in-back-of a bush we know it is farther. When it just passes over the bush or the tree we do not really know for sure its’ position.

So... When a plane is flying in a clear blue sky it is harder to guess the range. If trying to land on a flat field with few features then it will be hard to guess its range until it goes below the horizon and starts going in-front-of some features.
Binocular Vision - I learned about binocular vision several years ago when I briefly explored getting into "3D-Stereo-Photography". One of the first things that I learned was that you could have more than just the "standard" 63mm lens-to-lens separation (InterpPupillary Distance). For example you could make a better stereo photograph of the...Continue Reading
Posted by JD-Slow-Thumbs | Apr 21, 2017 @ 09:32 PM | 4,501 Views
This is version 5A1 in my series of helicopter collectives (used for flight sim home cockpits).  This is an intermediate level for DIY collectives and includes a Twist-Throttle.  

Here on YouTube
Collective BuildLog 5A1 (8 min 46 sec)

Thanks for watching

Please Comment at HoverControl.com
or at
Posted by JD-Slow-Thumbs | Apr 07, 2017 @ 01:13 AM | 5,009 Views
I like flight simulators in general,
and having some involvement with helicopters at a company that I work for,
I decided to look for collectives available for purchase on the internet,
and I what I found had a price-point starting at about $500 with fancier ones at about $1,200
so I decided to develop my own invention.

Having worked as a “Manufacturing Engineering Technician” (Process Engineering) in my recent past, I wanted to develop something that could be produced with COTS (commercial-off-the-shelf) material and needing a minimum of tools and a minimum of processing steps.

Over about a year I developed a series of collectives, the first four versions in this series make good Do-It-Yourself projects, while the fifth version would make a good KIT that would be complete enough to work nicely once assembled. This fifth version would also make a good platform for expansion, and very good for “kit-bashing”.

Thanks for reading

P.S. For this series of collectives, I figured out some requirements for the chair that I would need. Since I already had some woodworking tools, I chose a wooden chair as opposed to metal or plastic. Also I wanted a chair with straight sides as opposed to wide front and narrow back. I also looked for a chair that I could attach a joystick / cyclic to. The chair that met all of these requirements was a dining set chair found at a Salvation Army thrift store. (I planned on putting lots of holes in in,...Continue Reading
Posted by JD-Slow-Thumbs | Jan 08, 2017 @ 12:37 AM | 5,244 Views
Just got back from the AMA Convention in Ontario California.

At this convention, the vendors displaying their latest merchandise can also sell direct to the attendees and I came home with four rc aircraft:
1 – A MegaTech-A7-Tornado ducted-fan weighing 130 grams.
2 – An EH-Sabre helicopter weighing 219 grams.
3 & 4 – Two “Snap&Fly-Modularized-RC-Airplanes" starring the V-Tailed fuselage module. Each one only weighs 17 grams complete; fuselage module, power module, and battery. Dang, these guys are light.

The MegaTech-A7-Tornado is going to get some upgrades before I even try to fly it for the first time. Somebody was selling off an obsolete plane, new-in-box but obsolete: two channels; throttle, and left/right; also it had a small NiMH battery. So, first upgrade will be to add two servos for the elevators to get “Delta” control of the tail feathers (leaving the wings clean). Next is out with the brand-x two channel radio and in with a Lemon-Receiver-With-Stabilization (and delta capability). And lastly swap out the 7.2 volt NiMH (6 X 1/2AAA) battery for a 7.4 volt LiPo (2s) battery. Starting at 130 grams, staying under 250 grams will be the easy part, the hard part will be to maintain the center-of-gravity, this will take a lot of creativity and attention-to-detail.

Finally got the crimp tool for servo pins that I have been looking for forever.

Learned about a transmitter for rc cars that can talk to a PC for an rc car simulator.

Saw a presentation on terrain avoidance software that got it start using rc technology and rc parts and an Android smartphone. Good to see people starting with rc stuff and then up-scaling.

Thanks for reading
Posted by JD-Slow-Thumbs | Oct 20, 2016 @ 11:19 PM | 5,168 Views
I have an old NetBook with ms-windows-XP on it and it was slowing way down and a couple of times it woke-up less than the way I had left it. Time to clean it up and speed it up. So last night I installed a lite version of Linux called Lubuntu_16.04_LTS. The installation went smoothly and it seems to be working so far. This weekend I will be adding a very short list of programs and doing some configuration tweaks. It will mainly be for forum browsing, youtube browsing, and general web-surfing,

Thanks for reading

Dell_Latitude_X1 featuring a 12" WXGA (1280x768) display with a Pentium-M-733.

Depending on the age of the processor there might be an issue with PAE (physical address extension) capability, just need to add an entry to the installation command options. https://help.ubuntu.com/community/PAE

Finally found a straight answer on how to do a clean install.
Posted by JD-Slow-Thumbs | Sep 18, 2016 @ 10:54 PM | 5,585 Views
Here is another clip in my series on “Visualizing The KF-Vortex”.

Mounting a servo in the step area of the KF-Airfoil has been a very popular position for mounting servos. In this clip I demonstrate that mounting a servo here will disrupt the span-wise / sideways airflow possible in a KF-Airfoil-Vortex.

Thanks for reading

The discussion is over here,

20degreesWithServo 01 (0 min 48 sec)

Posted by JD-Slow-Thumbs | Sep 09, 2016 @ 12:24 AM | 5,527 Views
Michael_V commented to my previous post about “Visualizing The KF Vortex” and these comments were the perfect segue for me to expound on some of my theories.

Originally Posted by Michael V
Interesting. Love the crude wind tunnel.
Thanks, I am calling it a “Wind-Sluice” after water sluices that go to / from water wheel mills.

Originally Posted by Michael V
Since the vortex seems to travel towards the tip of the wing in a straight configuration, I wonder if the inner KF sweep is enough to reverse it completely, or if there is a neutral point along the wing where the flow reverses. That latter case could provide for some interesting tuning of wing characteristics and behavior. Reversing it completely might be a problem for the tip vortices as it may increase their size significantly, and that would be very detrimental to drag.
I already thought of this, and I see two best answers:
1A – A “Swept-Back” wing with KF-Step that always sweeps OUT and back like a flying wing or delta popular for slope soaring, without motor / propeller / prop-wash to mess with the directional flow of the vortex.
1B – Add motor / prop / prop-wash to the above flying-wing or delta but also add fences to isolate the prop-wash from the KF-Vortices.

2 – A “Forward-Swept” wing with KF-Step of course, that always sweeps IN, even if it is only 5...Continue Reading
Posted by JD-Slow-Thumbs | Sep 07, 2016 @ 09:51 PM | 6,724 Views
A while back I had an idea, a real lightbulb moment, regarding the KF-Airfoil, and finally I have a way to communicate it visually.

I had been interested in the KF-Airfoil for a while and when I came across the “Voyager” by Viking60 https://www.rcgroups.com/forums/show...&postcount=237
with its inward tapering KF-Step, it hit me that the faster propwash would not only pull the vortex inwards towards the wing root but also increase the speed / RPM of the vortex and increase the vacuum of the vortex. This is for a KF-Step that is at an angle to the primary airflow. I envisioned it as a rope-shaped vortex that curled under and at an angle. Here are a few still-photos of what I envisioned and a brief video that successfully shows airflow going at an angle instead of simply downwind. It looks convincing at 20 degrees, later I might go back and see how good it looks at 5, 10, 15 degrees.

Thanks for reading

Cool “Visual-Aid”!

The discussion is over here.

20DegreesSweep-01 (0 min 48 sec)

Posted by JD-Slow-Thumbs | Aug 23, 2016 @ 11:33 PM | 6,359 Views
This evening our local rc club was having its monthly meeting at the flying field so I went early to try to sell-off some of my larger / heavier / older batteries for ParkFlyers. Success, I made $40, ChaChing$
6 each 2,200mAh 3S 20C Turnigy LiPo Packs
2 each 1,800mAh 3S 20C Turnigy LiPo Packs
4 each 1,000mAh 3S 20C Turnigy LiPo Packs

And I donated to the club,
2 each 1,450mAh 3s(11.1v) 1c Transmitter Packs, and the transmitters they went with,
2 each FS_CT6B FlySky Transmitters, 6Ch radios that needs a PC to change settings

I will be flying planes under the 250 gram threshold. I already have electronics for four airplanes and a big bundle of blue Fan Fold Foam. My target size will be 40 inch wing-span (~1 meter) probably a little smaller

With my 250 gram threshold in mind I kept all of my,
800mAh 2s 20c LiPo Packs, and
500mAh 3s 20c LiPo Packs.

Thanks for reading
Posted by JD-Slow-Thumbs | Mar 26, 2016 @ 11:54 PM | 6,545 Views
HobbyKing advertised this motor with some specifications that make it a very good match for models just under 250 grams flying weight. Somehow I managed to buy four of them before I got around to bench-testing or flying any of them. Today I got a-round-to-it and bench-tested the motor, and got about half the thrust that I was expecting.

hexTronik 16gram Brushless Outrunner 1700kv (US Warehouse)
Voltage: 7.4v (2 cell Lipo)
Current: 6A
Suggested Propeller: 8x3.8
Thrust: 300g+

Kv: 1700rpm/v
Weight: 16g

I tested using the recommended propeller (APC-SF-8x3.8) and a two cell battery (2s800mAh20c) and a twelve Amp ESC. On my test-bench at full throttle the system maxed out at only 35 Watts and only 175 grams of thrust.

Checking for limitations and doing some math did not reveal any wattage limitations in the devices.
Motor 7.4Vx6A = 44.4W, capable of 44 watts steady state
Battery 7.4Vx0.8AHx20c =118.4W, capable of 118 watts available Now,
ESC 7.4Vx12A = 88.8W, capable of 88 watts steady state
Bummer I was expecting 44watts and 300 grams of thrust.

Further testing with a variety of 6, 7, and 8 inch props, gave a pretty consistent 5-to-5.5 grams of thrust per watt.
Since 175 grams of thrust was not what I wanted for a model just under 250 grams, I decided to swap-out the two cell battery (2s800mAh20c) and swap-in a three cell battery (3s500mAh20). Full throttle promptly exceeded 50Watts, so I continued my study while manually limiting...Continue Reading
Posted by JD-Slow-Thumbs | Mar 21, 2016 @ 11:36 PM | 6,696 Views
I really wanted a table-top belt sander for my upstairs rc-airplane shop, but never got around to spending the money to buy one. Since I already had a hand-held-portable belt sander, I decided to build a base to hold the sander in a fixed position and also provide a work platform for the piece to be sanded. I used three layers of 1/2-inch particle board (MDF), the top two were cut in the outline of the sander, while the bottom layer held up the main body of the sander but had a cut-out for the motor air intake. Glued it together with gorilla-glue and clamped it overnight last night, and this evening after work I ran it through the table-saw to trim the sides. Used the sander in portable mode to finesse the edges and clean it up.

I like it, version-1 turned out a lot better than I thought it would.

My upstairs rc-airplane shop now includes:
-tabletop drill-press,
-tabletop band-saw,
-tabletop belt-sander,
-small grinding-wheel,
-paint bucket vacuum usually attached to the band-saw.
I can do almost all of my building in my upstairs playroom

Thanks for reading

BTW not only is my portable sander on sale at Harbor Freight but so is the tabletop version that I wanted. This is still cheaper and good enough to meet my needs for a long while.
Posted by JD-Slow-Thumbs | Feb 27, 2016 @ 03:23 AM | 6,597 Views
After carefully considering my options, I decided to stay under the 250 gram threshold for registration, for at least the next year or two.

Therefore I decided to get rid of the stuff in my fleet that was only use-able on planes heavier than 250 grams and having missed out on the opportunity to sell at a club swap meet, I took my stuff down to the rc airfield this afternoon and tried to sell it. Success! Somebody actually paid me a little money for my collection of stuff.

The stuff included:
2 HP SuperFly fuselages, modified, EasyStar derivative,
1 HK Bixler fuselage, modified, EasyStar derivative,
6 Wing sets joined together,
11 Motors, brushless, various sizes for ParkFliers,
2 HP Radios, 2.4GHz, Transmitter + Receivers sets
Come to think of it, this collection of stuff was not RTF or ARF but just KIT stuff for builders , I was lucky to get any money out of it at all.

The plane is dead, long live the next plane!

Based on a 16gram version of the Blue-Wonder brush-less motor, I will be flying planes under the 250 gram threshold. I already have electronics for four airplanes and a big bundle of blue Fan Fold Foam. My target size will be 40 inch wing-span (~1 meter).

Thanks for reading

hexTronik 16gram Brushless Outrunner 1700kv (US Warehouse)
Posted by JD-Slow-Thumbs | Feb 25, 2016 @ 12:21 AM | 6,230 Views
Over in the “Model Aircraft & Drone Advocacy” forum, MeHere posted a news article and question.
Do you think Drones should be able to fly over people?

I responded in part:
Yes - If the aircraft has a usable Glide-Slope, so that it can avoid crashing into pedestrians on the sidewalk or cars on the freeway. Presuming that said drone would be flying at least 200 feet Above Ground Level*, even a bad glide slope of 2:1 would yield a 400 foot radius for avoiding people on the ground. *(Amazon proposed a 200 - 400 ft AGL band for commercial drones).

I also mentioned that Manhattan would remain off limits for lack of safe places to ditch a gliding drone.

Thanks for reading

The discussion and my reply is over here
Posted by JD-Slow-Thumbs | Feb 18, 2016 @ 10:00 PM | 6,494 Views
My bungee-cord-catapult works much better now, stronger throws and more consistent. Thanks to replacing the skinny-cloth-covered-bungee-cord with fatter-yellow-latex-surgical-tubing. Also replaced the fixed eyelet (pulley) with a real pulley complete with enclosed ball bearing. Now I have a launch system that can give my models/experiments a worthwhile throw.

Test reports coming soon
Thanks for reading
Posted by JD-Slow-Thumbs | Dec 07, 2015 @ 11:36 PM | 6,942 Views
Well I got a chance to try out my catapult and it was totally wimpy I think there is too much friction in the “pully” system where the bungee cords' cloth covering goes around stationary eye-hooks. At the field I could not get it tightened-up enough to get a decent launch. After all that work building that catapult, I ended up hand launching after-all. So much for calibrated consistency.

The test glider, my JD-12, is a delta front with a squared off back, using a KF-step of 3/4 inch, swept back 30° bilaterally, 30 inches wide, 20 inches nose to tail. (20x30 that sounds familiar from somewhere). The airframe itself, just the Blue-FFF and R-Tech foam and a spritz of 3M-77 adhesive and 3 inch wide packing tape weighed only 104 grams. To represent the weight of the electronics and miscellaneous hardware I used a roll of pennies. Did you know that a roll of pennies weigh about 130 grams. Anyways my all-up-weight was 234 grams which is real close to the probable registration threshold of 250 grams. I have a 40 inch wingspan version where the foam air-frame only weighs 124 grams.

Between the wimpy catapult and 15 mph gusts I did not get very far with my experiment. I was lucky to get a reasonable Center-Of-Gravity figured out. I think. For an easy throw, it floats along very nicely. But for a hard / fast throw, it curves up, stalls, and nose-dives. It leaves me wondering if the Center-Of-Lift can change depending on airspeed. Or it might just be that darned gusty wind.

Here is a picture.
Thanks for reading.

Requires Further Research !
Posted by JD-Slow-Thumbs | Dec 05, 2015 @ 12:33 AM | 7,718 Views
I think that I see something special in the Kline-Fogleman stepped airfoils and since I love to experiment I decided to do some experimentation to test some of my theories. In a earlier discussion BMatthews suggested that I build gliders for my testing. He also suggested building a system to get a consistent “Throw” so that flight times and/or flight distances could be compared. Good idea.

I spent last weekend building a catapult with a 30° slope, and ran out of weekend before I could try it out. During the week I decided that 30° was too steep and too tall, so today I modified it to be only 15° slope and not so tall. This had the added benefit of fitting into my car easier.

My catapult is based on 8 foot long twin rails, that are 3 inches apart in this version, with a 15° slope. I used 2x3 inch boards from Home Depot and some leftover plywood for the basic shape, and 1/4-20 carriage bolts and matching fender washers and wing-nuts for ease of re-assembly at the flying field. In this version the rails are 3 inches apart to accommodate my two HP-SuperFly's (EasyStar derivative) and my two Air-Hogs-Titan's. This rail separation will also work good with my experimental deltas once I add small “keels” to them. In my next version of this catapult I will probably use forks that hold the rails about 9 inches apart to accommodate planes with 8 inch propellers. The forks that set the rail separation are modular / swap-able. I almost forgot to mention that it uses a long bungee cord to accelerate the aircraft. The bungee cord started out life as a cargo net from Harbor Freight.

Here are a couple pictures.
I plan on trying it out tomorrow.

Thanks for reading.