JD-Slow-Thumbs's blog View Details
Posted by JD-Slow-Thumbs | Apr 21, 2017 @ 09:32 PM | 1,693 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 | 2,088 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 07, 2017 @ 11:37 PM | 2,435 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 | 2,408 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 | 2,725 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 | 2,648 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 View Post
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 View Post
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 | 3,887 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 | 3,617 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 | 3,675 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 | 3,843 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 @ 02:23 AM | 3,811 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 24, 2016 @ 11:21 PM | 3,424 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 @ 09:00 PM | 3,691 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 @ 10:36 PM | 4,161 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 04, 2015 @ 11:33 PM | 4,915 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.
Posted by JD-Slow-Thumbs | Dec 04, 2015 @ 10:42 PM | 4,543 Views
I think that I see something special in the Kline-Fogleman stepped airfoils and since I love to experiment I thought that I would build a tabletop-wind-tunnel to test my theories.

Well … I started out asking for suggestions for cheap telemetry, and, ended up getting a quick education in wind-tunnel design, and came to the conclusion that I would not get very far using any blower compatible with the 15 Amp 115 Volt house current in my garage.

HugePanic suggested that I setup my experiment on top of my car so that I could get 60 mph airspeed without the hassle of buying a motor plus blower with large cubic-feet-per-minute and then fine tuning the turbulence out of a wind-tunnel. I will probably get around to a car-top experiment later.

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 liked it enough to start down this path next.

Thanks for reading.
Posted by JD-Slow-Thumbs | Dec 04, 2015 @ 07:41 PM | 4,026 Views
Originally Posted by Ldm View Post
I see this the most feasable in the pharmacy segment. Small packs, light weight, urgent deliveries of meds etc .
I saw this and gave a response worthy of a Business Major

I totally agree with pharmacy deliveries. - From a regional hospital or pharmacy to smaller satellite hospitals and nursing homes. Everyday, nursing homes and small hospitals need something that they do not already have. Currently regional pharmacies need to own a fleet of cars/vans and hire drivers, usually to make once daily delivery routes, (I remember, order by 3pm and receive it by 8pm, the backup plan is a local pharmacy and local taxicab company).

The reverse would apply to medical lab-work getting picked up from outlying doctor offices and going to a central / regional medical lab. Again this is currently typically a once daily pickup route with the lab providing overnight service so that the doctor can deal with the answers the next morning.

Also I can see a lot of businesses wanting to get their afternoon small shipments to the FedEx terminal after the standard 3pm pick-up time.

So Yes, I can see a few commercial applications for drone delivery and pick-up service. Actually I see fast pick-up, so that you do not lose a cycle of once-daily service to be the most urgent business demand. So far I am not seeing the demand from the consumer sector.

Can any of you all think of any more high volume commercial needs for drone pick-up / delivery service.

Starting to get more interesting,

P.S. Someday it would be interesting and fun to place an order for hot pizza and cold beer and receive it by drone.

But I think the chances of ordering anything off the beaten path like "Rotor_Drone_Magazine" or "Model_Airplane_News" or a book like "Drones_for_Dummies", would result in a message saying "Not-Available-For-Drone-Delivery".

The discussion is over here
Posted by JD-Slow-Thumbs | Dec 01, 2015 @ 09:35 PM | 4,317 Views
While weighing the elctronic components for my Sub-250g-Flying-Machine, just for fun I decided to weigh my Smart-Phone, and it weighs 222 grams ! (LG-VS880 with crash resistant cover).

This is giving me a little perspective on just how Freaked-Out The Establishment Is.

I bet that somebody here has a smart-phone that weighs over the 250 gram threshold.

Thanks for reading.

"Establishment", for a guy way over thirty, I sure am sounding like a dang hippy.

Discussion is over here

Recently the DOT/FAA commissioned a task force to make suggestions for how to implement national registration of “Drones” including traditional R/C-Airplanes, so that a crashed drone could be traced back to its owner, and among other things they recommended that anybody operating a drone over 250 grams be required to register as a “Drone-Operator”. In response to this situation many people in this forum are very unhappy about it and really going nuts about it. Meanwhile I am only a little unhappy about it and I am currently developing scratch-built-foamies intended to fit under this 250 gram threshold.
Posted by JD-Slow-Thumbs | Oct 06, 2015 @ 11:10 PM | 4,920 Views
I am doing some catching up on my writing tonight. A few months back (April 2015) I built another plane, the JD-11, and it has some good potential, but it also needs some refinement / reinforcement. It is a slow flying Delta, has a 48” wingspan, 20” length of blue foam, 26” from prop-spinner to rudder. It has a 100 Watt power system, Blue-Wonder/HexTronik-24grams 3s/1500kv motor, one of my bamboo motor mounts, 12Amp ESC, 1,000mAh/3s/20c battery, 6x4 MasterAirScrew GF propeller, and last but not least a Lemon receiver with DSMX and stabilization and delta mixing all built in (works good with my newly upgraded 9X transmitter).

I got one of my buddies to maiden it, and he said that I needed to adjust my Center-Of-Gravity. Before building it I had studied COG for deltas, and found settings for beginner / intermediate / advance. Now I thought that COG meant the balance point between the front and back, you know 50/50 and make minor adjustments from there. Well I was quickly reminded that Deltas “need reflex” where the nose is up a little, most of the wing is down a little, and the Elevons (elevator-ailerons) point up a little. Apparently for slow flying a Delta, beginners should have a little more of the nose-up higher angle of attack.

Something else we quickly noticed was that the wings were bending upwards, not hinging at the root, but curving upwards trying to look like the bottom of a circle, not good for consistent control with those elevons. An easy fix for some carbon-fiber tube.

Here is the best picture.
Thanks for reading
Posted by JD-Slow-Thumbs | Apr 05, 2015 @ 02:58 AM | 5,322 Views
Last Thursday 3-26-2015, I got six flights on my latest plane, the JD-10. It was a chuck glider conversion, starting with an Air-Hogs-Titan and adding electronics. The star of the show was a Lemon Receiver featuring DSM-X + Stabilization + Delta-Mixing all in one small unit + a small satellite/diversity receiver. Once I got it airborne it worked good.

Other features were as follows:
1 – The Air-Hogs-Titan has wings that are both swept back and have dihedral, probably resulting in a strong self-righting dihedral effect.
2 – The As-Found center-of-gravity for the chuck glider before adding electronics was approximately 5-1/2 inches back from the leading edge of the wing root (~3/4 of wing root), and when adding the electronics I balanced the components to maintain the same center-of-gravity.
3 – After determining the As-Found center-of-gravity, I placed a piece of heat-shrink across the top of the fuselage so that I could repeat the balance point (see picture below). I have used this several times now and it works great for repeatably balancing a plane.
4 – I added left and right elevator so that I could use them as elevons (Delta). I also added rudder mostly for later use. Because I wanted to keep all of my wiring and servos on the fuselage and integrated empennage (tail), and because I wanted to keep the known-good wings clean, I did NOT add ailerons. Of course, these control surfaces used three servos, and I used 9gram servos because sometime in the...Continue Reading