HobbyKing.com New Products Flash Sale
randall_l's blog
Posted by randall_l | Yesterday @ 08:35 PM | 573 Views
Well, last weekend was good--sunny and little to no wind.

I got the Junior 700, HK Versus and FT F-22 maidens done.

Junior 700 maiden:
I used the farthest back I could find CG scaled down from some Junior forums (51.2mm from LE) for the maiden. Pretty hairy flight, I'm glad I had flown my MiG-7 beforehand to juice up my reflexes. Managed to get it down with no damage.

I added ballast (about 12g) to the nose and that moved the balance point up to 42mm. Second flight was superb! If I were building her again, I would change the AoA of the horizontal stab to be a bit positive (LE above TE) to avoid having to trim so much down elevator. Thank goodness I put C bends in my control rods.

My wife was kind enough to get some video of my flights, so I'll massage them up and put them on my YouTube channel when I get a chance.

I flew the Junior to work a couple times this past week. It's definitely my new favourite. Super docile and definitely a floater--cruises at about 1/4 throttle.

HK Versus maiden:
I did a couple hand launches to get it trimmed, boy does it make my scratch-built mini ELF seem like a brick!

I'm still recovering from a sprained ankle from last July, but I gave a light launch and exceeded my full knacker launches with the mini ELF--and quadrupled the air time.

All I can say is, "I LOVE THIS BIRD!!!"

If I wasn't addicted to DLG before, I most certainly am now. The bad news (well, not really) is that my 2.5 year old daughter...Continue Reading
Posted by randall_l | Apr 12, 2014 @ 11:43 PM | 1,133 Views
So I had the opportunity a few weeks ago to assembly my swappable fleet for sort of a family photo. I thought I'd share it.

No mention of wind in the forecast for tomorrow so far, so I'm getting excited about some maidens: Prime Jet 8 (re-maiden); FT F-22; The Fat Lady; Junior 700; HK Versus are all waiting.

I've just started a swappable Bohm & Voss BV-141. Details to come soon.

Posted by randall_l | Apr 11, 2014 @ 09:50 PM | 1,089 Views
New member of my swappable fleet

Seeing spocktra50 (YouTube channel) fly around his Durafly Retro Series Junior, I got inspired. Based on Mark's videos and the threads here saying that the ailerons were fairly ineffective, I decided to do 2 wings: a high (24-degrees) dihedral wing with no ailerons; a low (12-degrees) dihedral wing with ailerons.

Introducing the Junior 700 (pictures attached)...
Wingspan: 706mm (high dihedral); 712mm (low dihedral);
AUW: 194.7g (high dihedral); 207g (low dihedral);
Pod: 2S pod

I used the Junior 60 (1955 reprint) plans from Keil Kraft (downloaded from Hip Pocket Aeronautics) for the build. The maiden will have to wait for the wind to die down, but I'm really excited about this one.

Other projects

My HK Versus is complete and waiting for maiden. AUW is heavy at 296g, but I'm using the excuse that it's my first kit.

The swappable Gee Bee R3 is mostly complete. There are a few pieces of skin to put on after I affix the wing and I still need to decide on a paint scheme.

Posted by randall_l | Mar 14, 2014 @ 09:07 AM | 2,138 Views
Measuring Thrust

I recently found out that the rig I was using for measuring thrust was very inaccurate. The postal scale that I scavenged from the recycle-bin where I work (with permission of course) was not accurate at all between 200g and 1kg.

So, I built a balance-type thrust rig and tested with a weight set. After determining that the new rig is out by 1.1g at 1kg, I started re-testing my power setups.

3S Power Pod:
Motor: Turnigy SK3 2122-2100kv Brushless
ESC: Turnigy Plush 12A Brushless w/2A BEC

2S Power Pod:
Motor: Hextronic 20g Brushless 2300kv
ESC: Turnigy Plush 10A Brushless 1/2A BEC

3S LiPo: Zippy Compact 3S 500mAh 25C LiPo
2S LiPo: Zippy Compact 2S 500mAh 25C LiPo

Prop 1: Turnigy Sport 6x4
Prop 2: APC style 6x4

Thrust (average of 3 runs):
3S Power Pod, 3S LiPo and Prop 1: 706g
3S Power Pod, 3S LiPo and Prop 2: 663g
3S Power Pod, 2S LiPo and Prop 1: 354g
3S Power Pod, 2S LiPo and Prop 2: 288g

2S Power Pod, 2S LiPo and Prop 1: 284g
2S Power Pod, 2S LiPo and Prop 2: 229g

1S Setups
AP05-5000kv Brushless, XP7A ESC, Eflite 1S 200mAh 30C LiPo
GWS 4540: 79g
GWS 5030: 92g
GWS 5043: 81g

With the results above it appears that the Turnigy Sport 6x4 is the better propeller for my purposes, but for a thorough comparison I'll have to use my watt meter.

Posted by randall_l | Feb 09, 2014 @ 05:51 PM | 1,642 Views
Let's see if I can make good on New Year's Resolution #3: Make at least bi-monthly blog entries.

I managed to get several projects completed over the past couple months.

Next, inspired by the Japanese indoor flyers (user: tyoukogatalabo on YouTube), I tried to build a sub 40g Pitts Special. Coming in at 34g and being very unstable, I added a hook to use on my daughters ceiling flyers (fishing line from a hook on the ceiling to a plane that goes around in a circle).

After that, I started working on a built-up wing with ailerons for my Mini Elf v3 and assembling a HobbyKing Versus. When I came to the realization that the servos I purchased for the Versus (recommended by HobbyKing on the USA warehouse version) weren't even close to adequate, I ordered more servos of different types.

During the wait time, The Flitetest folks released a F-22 with a bunch of improvements, so of course I couldn't resist making it a swappable, wingspan: 547mm, AUW 221g.

Still waiting for my orders to come, I got the hankering for another sub 40g attempt.

I decided (once again inspired by the Japanese indoor flyers) that I would build a mini Alula clone. As per usual, I added my own twist to the design with a KFm-2 airfoil and a swappable motor/glider pod. Wingspan 500mm, Glider AUW 32g/Motor AUW 37.4g.

I had to make a compromise against my principles and add 2.1g ballast to the glider pod to achieve the rearward CG. The motor pod is a bit nose heavy, but I'll see how it goes and maybe move the battery back.

Posted by randall_l | Dec 30, 2013 @ 06:58 PM | 1,518 Views
I've had enough time over the last couple weeks to get my P-51 Mustang almost completed.

I'll need to reprint the tail markings to the correct size (they were way too large on my initial printing) before applying them. I just couldn't wait to share some pictures.

The paint scheme is loosely based on Cripes A' Mighty. I had found an image of either a 3D or simulator rendering that had too much transparency on the invasion lines and thought, "Wow, that looks amazing!" So, I tried to emulate that using a mix of Tamiya acrylics (Titanium Silver, Chrome Silver and White for the light stripes; Gun Metal for the dark). I think it turned out pretty well.

EDIT: I found the image again here: http://www.352ndfg.com/vb/content.php?234 --didn't want to just upload the image in case of copyright infringement.

EDIT #2: The fuselage is 13mm wider than it should be for this scale (1/19) to accommodate the power pod. Part of the reason for the name. The other part is that I occasionally pilot well enough that my planes seem to 'sing'. (fat lady singing)

Name: The Fat Lady (as in, "It ain't over until the fat lady sings")
Wingspan: 606mm
Airfoil: KFm7 (50/67/100/75 %)
AUW: 208.2g (with 3S 500mAh 25C LiPo and 3S pod)

I'll wait until the snow disappears to do the maiden. There's a layer of ice on top of the snow right now that chews up foam (even when covered with packing tape) pretty bad.

Posted by randall_l | Dec 21, 2013 @ 10:54 PM | 1,621 Views
Another night, another couple hours of 'insomnia time'.

This session yielded an ornithopter, thanks to Doreen Campervan's 'Make an ornithopter' video on YouTube. I only had to make some minor changes to get it to fly: add a second bend to the crank to even up wing movement; add a bushing to the front of the crank tube to smooth rotation; increase the length of the wing cranks to increase stability.

Construction materials are: bamboo barbecue skewers, cotton thread, 3mm basswood plywood, tube from can of compressed air, washer, 0.8mm music wire, carbon fibre rod, heat shrink tube, tape, gift-wrap cellophane, CA glue.

I had no idea how easy it was to create such an amazing machine. Weighing in at 10.2g, this 357mm (wingspan) engineering marvel takes it's place as the lightest non-paper aircraft I've made to date.

The gears are turning now... I can see several ornithopters in my future: pig ("When pigs fly"); monkey (Wizard of Oz); horse (Pegasus, from Disney's Hercules for my daughter); dragonfly.

My first goal is going to be an RC ornithopter, then progress to something like the beautiful ones in this video:
20121008SSFC SAFETYQuadcopter&Slowbirds (3 min 43 sec)
(starting at 1:14).

Posted by randall_l | Dec 20, 2013 @ 12:11 AM | 1,892 Views
Several airframes have happened since May, namely:
-Old Fogey v2(Flitetest Swappable);
-slightly-larger MiG-7 swappable(room to put battery inside the fuselage);
-Zazu swappable;
-Witch swappable;
-ultra-light 1S plane I call the 'Mosquito' (as in sounds like);
-KFm4 DavidWing (here on RCGroups);
-2x scratch-built KFm4 Assassin wings;
-FanJet trainer (here on RCGroups)--didn't last more than 2 flights;
-Prime Jet 8 (here on RCGroups, but made swappable).

Old Fogey v2(from Flitetest):
-tail feathers and front part of the main wing are 3-layers of 1mm Depron for increased stiffness;
-tail feathers strengthened with CF strip in the middle layer;
-main wing strengthened with 1mm basswood ply elbows and CF strip going right to the wingtip;
-nav lights on wing tips and wing/landing lights for night flying;
-nose strengthened with additional 3mm Depron and CF strip.
-channels: RET;
-wingspan: 585mm;
-AUW (with 2S pod and Zippy Compact 2S 500mAh 25C LiPo): 152g.

MiG 7 v2:
-tail feathers are 3-layers of 1mm Depron strengthened with CF strip;
-main wing is a 50% - 75% - 100% - 67% KFm7 airfoil with 2 CF strips which gives amazing full-size-like performance (based on footage of the MiG 3 and the ease of recreating the maneuvers) on such a small plane;
-aileron servo in each wing and a flapperon mix;
-channels: RETAA
-wingspan: 642mm;
-AUW (with 3S pod and Zippy Compact 3S 500mAh 25C LiPo): 183g;
-Using the HK Doppler iPhone app it was clocked at 92kph.

...Continue Reading
Posted by randall_l | Dec 17, 2013 @ 09:22 PM | 1,426 Views
I still owe an update on what's been happening since May, but here's what I've been working on the past 3 days...

A tricopter. I got inspired by the Mark and the gang over at spocktra50 on YouTube.

Arm length (centre of frame to centre of motor axle): 150mm
Motors: hexTronik 20gram Brushless Outrunner 2300kv
ESCs: Turnigy Plush 12A Brushless ESC w/2A BEC (only one used for powering rx/servos)
Tail servo: Turnigy TGY-D1290P
Battery: Zippy Flightmax 2S1P 1000mAh LiPo
AUW: 226g

I had all this stuff sitting in parts drawers, so it didn't cost me anything extra. Of course, I'll have to buy some better props--likely 6x3 or 7x3.

The major setback however, is that the FY-30a that I had planned to use (also sitting in my parts drawer) is hooped. It still works fine for flight-stabilization but for fixed-wings only. The UART part isn't functioning anymore--I tried all the fixes for "USB device not recognized" that google had to offer.

I'll have to wait until I decide to buy a multicopter controller to get it off the ground.

On the plus side, it was one heck of a good time.

Posted by randall_l | May 18, 2013 @ 07:35 PM | 3,565 Views
I think I've just about got it now.

After hearing in one of the recent Flitetest videos about a swappable glider, I thought "I'm almost there already--just missing a couple components"

So during my mid-night waking times this past week and most of today, I set about finishing up the components for a modular mini glider platform.

I'm waiting for delivery of a XP7A 1S ESC and an AP05 5000KV brushless motor to finish up the motor pod. The AP03 7000KV brushless motor shown produces about 30g--way too little.

My next task this weekend is to work on assembling the mini vacuum form chamber I've been working and create the molds for covering the pods. I'm also waiting for some 3mm round x 1.6mm magnets to hold the pods on.

Once finished, the glider and motor pods are field-swappable.

Posted by randall_l | May 05, 2013 @ 09:13 PM | 2,422 Views
Well, I've gone and done it now...

I finished the build of the motor pod for my Mini-ELF v2. I made a micro JST (1.25" pitch) adapter with only signal going to the 1S 5A brushless ESC. The ESC plugs into the second set of battery pins for power. The battery powers the receiver directly.

Now for the time to test it out.

AUW is now 80.3g

The pictures show both the motor pod (installed, foreground) and glider pod (background).

Now I just have to come up with a method for easy field swap-outs. For now, I may just use a second receiver. It'll have to change once I get the skin formed and installed.

Edit: The motor is a HobbyKing AP-03 7000kv Brushless Micro Motor and the prop is a Plastic Folding Propeller Assembly 4.5x3.

Posted by randall_l | May 05, 2013 @ 09:44 AM | 2,635 Views
Just got back from the field with my mostly rebuilt Mini ELF. I think I may have it right this time.

The last build used Blue Arrow S03614 high-speed single-cell servos and a CF reinforced 1/32" plywood frame covered by foam and cruciform tail. This time, I opted for HK-5330 UM digital servos and a V-tail. I'll be vacuum forming a skin for the pod hopefully soon.

The new pod design allows me to remove the bottom and replace it with a motor pod which I have yet to build, converting my DLG into something more.

AUW is now 80.9g, including 2, 1S Zippy Flightmax 400mAh 30C LiPos. I also reduced the main wing AoA from 4 degrees down to 1 degree. Darn is this thing fast and has a much better glide slope than the previous build.

There's a soccer tournament at all the available fields in town this weekend, so I'm using the time to build and repair.

Posted by randall_l | Mar 08, 2013 @ 08:40 AM | 1,888 Views
I got some almost usable video of the MiG-7 flying last weekend.

MiG-7-Prelim0 (2 min 0 sec)

With the KFm2 airfoil and tapered wings, it has a high stall speed. I expected that it would, being a high altitude intercepter. The cruising speed is at half-throttle--not because of thrust, but because of it's stall speed.

I also made some more progress on the Gee Bee R3 (attached). I have to figure out how I'm going to mount the landing gear before I finish covering the wing.

While reading through some of the Flitetest forums, I found a neat project: http://forum.flitetest.com/showthrea...o-make-it-fly)

After getting permission from the poster (for developing his idea), I started on a swappable build of my own take on the project (attached). I'm headed to the hobby shop this weekend to pick up the paint I need, but I'll make sure it flies before I paint it.

On the down side, my workspace got too cluttered yesterday and when I moved my notebook, my 9x fell off the table. The only appearant damage was to the throttle-cut switch, which snapped off. Fortunately I had another switch to replace it with, so it's back in service now after a couple mechanical and range checks. I've also put a pair of hooks in the wall above my workspace to hang the radio from, but still be accessible and usable. What good are mistakes if we don't learn from them.

Posted by randall_l | Feb 16, 2013 @ 05:16 PM | 2,315 Views
I've been building, flying, repairing and lots of learning over the past year.

Where to begin, hmm...

I messed around with Dave Powers parkjets--didn't really learn anything useful there except that my interests lie elsewhere. I built a T-50 (PakFa), flew it a couple times, then repurposed the parts. I also built an Extra300, which I quite enjoy now that I've modified and rebuilt it to my liking (scaled it to 664mm and added a KFm3 airfoil).

I did some odd builds from plans found at Hip Pocket Aeronautics Builders' Plan Gallery--found lots of planes I want to build. I built a 480mm Fokker DR.1 and a 910mm Spitfire Mk.22.

Found some plans on RCGroups and other places. I built a 740mm Ikon A5 and a 205mm witch bi-plane,

Then, I found Flitetest. After watching all the videos, I decided that I'd like to give swappables a try. I built a scaled down (60%) power pod for 2S and mounted the rudder and elevator servos on the pod for ease and cost savings, attached. I built a scaled down 560mm Old Fogey (again 60%), attached.

Edit: Interesting (to me anyway) story about the Old Fogey. I kept getting asked how high it would go. My normal answer is, "Farther than I can see." But I got curious (and had some telemetry gear sitting around), so I fitted it to the Old Fogey, reset the altitude and sent it up. I lost visibility at 368m. Thanks to a cut throttle and a couple clicks of left-rudder I regained visibility a few seconds later. At least now I have a...Continue Reading
Posted by randall_l | Apr 13, 2012 @ 08:57 AM | 2,384 Views
After completely destroying the airframe for my first FMS Stuka my wife said to me, "You're not taking your big planes up until you can fly one of those profiles without crashing"

Sounds like an okay to build more planes to me. After 'Dora' (which is partially painted now), I figured I should do an Allies plane. My collection is more German in nature (FW190A7, FW190D9, Ju-87 Stuka with plans for a BF-109, Ho-229 and Fokker DR1).

I had and since retired a Parkzone UM F4U Corsair (the guts are in 'Dora' now) and thought that I'd like to do something different. The Spitfire Mk22 fits the bill.

Thanks to the Printed Model thread here, I found HipPocket Aeronautics and their builder's gallery. I downloaded plans for all the models I want to build (and more!) and started with the Spitfire.

Yesterday was the maiden flight. The hardware is inspired by RCPowers: MicroJet V3, 4x 9g Grayson Hobby servos, 35A ESC, 3S 2800mAh Zippy FlightMax and the TX/RX that came with my Flyzone RTF FW190. Oh, and I had a Master Airscrew 8x6 prop for the maiden but have since changed to a 6x4. The 8x6 allows it to climb vertically (so awesome!) but puts too much strain on the motor.

The wingspan is 49-inches--right about in the middle of my 2 larger planes (the Stuka at 55-inches and the FW190A7 at 44.5-inches). Oh, and it's got a KF2 airfoil.

I really LOVE building my own stuff. Both the planes I've built are really docile and a joy to fly. I realize my models aren't great, but they fly well.

I get so excited when I look outside and see the wind level low now. Before, I used to look outside and think to myself, "Good flying weather... meh. Maybe later."

Now, I think to myself, "Woohoo! Flying time!" and ask the boss if I can take some vacation time.

Anyway, here it is after the maiden...
Posted by randall_l | Mar 17, 2012 @ 10:14 PM | 2,577 Views
I went out after dinner and killed 2 more pairs of batteries before the light level got too low (lost sight and landed in a tree, oops).

I adjusted the rudder control rod, giving it a bit of right-rudder to compensate for not having enough angle on the motor mount. I also set aileron dual-rates at 65%, 45% and 25% on my DX8.

I can see why this variant was often used for high-altitude combat--WOW! 65% rate is superb for aerobatics and 45% is amazing for scale flight, but 25% is a bit too tame at the speed the present power system can provide.

I had lost a lot of confidence when I crashed the Stuka. I guess seeing $500 in plane/electronics and several hours of build/refine time smash into pieces will do that to just about anyone. The $0 D9 quickly restored that. The most accurate word that comes to mind about this plane is: grace.

The flights I had tonight were easily the best and most fun I've ever had. Maybe it has something to do with building the plane myself, but I really felt connected to it. The D9 flies like my 45" and 55" planes do (but it's only a 16" ws).

I'm so very excited about the hobby again that I can barely contain myself.

I've been mulling a couple other ideas around and even started a 48" Spitfire Mk22, but now I'd like to do a flying wing (Horton 229) and a triplane (Fokker DR1).

Yee haw!
Posted by randall_l | Mar 17, 2012 @ 08:12 PM | 2,590 Views
Finally had the right mix of warm enough and still enough to maiden her today.

I had the wife video the flights with her camera, but will have to do some major editing to get anything useful. We'll have to practice together so she can get more familiar with flight filming.

The brushed motor from the Parkzone UM F4U Corsair is way too little power. I'll probably end up getting a brushless AP05 3000kv motor from HobbyKing. Right now, it won't be doing any dog fighting.

The KF2 airfoil on the main wing causes any aileron input to be super effective. I was completely unprepared for just how sensitive they would be. A typically normal flight correction caused a very quick barrel roll. I had to dual-rate them down to 50% to tame them enough to fly normally.

Three flights, the first one a bit rough but no damage. All in all, I would say it was a successful test. Not bad for $0!
Posted by randall_l | Mar 08, 2012 @ 06:12 AM | 2,901 Views
Just an update.

I used one of the 3-way Y adapters from the Stuka to extend the aileron wires.

The AUW is 50.7g. I think it's about as ready to fly as it'll get. I'm planning on Friday after work for the maiden. Hopefully I can convince the wife to come out and video it.

So far, $0 spent--just salvaged parts and bits of foam too small to use in larger models. Here's hoping it'll fly.

Posted by randall_l | Mar 03, 2012 @ 03:34 PM | 2,596 Views
Okay, so I've had the guts of my Parkzone UM F4U Corsair for over a month and I started thinking that I should throw some scraps together and see what I come up with. I love to tinker.

After following Jon on his Micro Focke Wulf Fw190 thread and seeing the mean paint job over at ModelAces, I decided on the FW190D.

I used a couple of the CF strips from the FMS Stuka, the electronics and control horns from the Parkzone UM F4U Corsair and some other scraps and bits I had lying around.

The only thing's I'm going to need to buy are a pair of 3-inch servo extensions for the aileron servos.

Before you snicker and sneer, be aware that I have zero experience with scratch builds and this is just something I'm messing around with. I have no expectations for this model except for it being fun to do--which it has.

I haven't flown it yet--still waiting to get to my LHS for some servo extensions, but it glides true and is balanced. The CoG is at the CF wing spars with the two batteries. Wingspan is 16-inches and AUW is 50.2g (excluding the servo extensions).

So, here's the experiment...
Posted by randall_l | Mar 03, 2012 @ 02:45 PM | 2,495 Views
I've been a member for a while, so I guess it's about time I introduce myself.

My name's Randall. I live in rural BC, Canada.

I've been into RC off and on for about 25 years. About 2 years ago, I got into toy helicopters (Litehawk). 6 months later, I got into planes (Parkzone ultra micros).

Attached is my current collection, from back-left to front-right: Flyzone FW190, Parkzone UM J3 Cub, Litehawk, Litehawk Pro, Litehawk XL, Blade mCP X v2, XMODS Corvette, XMODS Mustang.

What's missing: FMS Stuka, which met it's end a couple weeks ago and; Parkzone UM F4U Corsair, which I salvaged parts for other projects.