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RPM314's blog
Posted by RPM314 | Mar 02, 2015 @ 03:16 PM | 1,281 Views
NASA's Albion H. Bowers - " Why Birds Don't Have Vertical Tails" - AMA EXPO 2014 (38 min 48 sec)

In light of this information, the Falcon mk.Vb has been scrapped WILL STILL BE REBUILT FOR AEROBATIC FLYING, and I will begin to work on a new sport plane based off Prandtl's lift distribution and the Horten brother's work. I anticipate that a 4 flap wing will be necessary to maintain the proper downwash in a wider range of flight conditions.

The physical model is designed and the proper twist has been calculated, optimized for a lift coefficient of 0.5. The elevons are interesting, only partially hinged, and the outboard sections are all-moving wing. I cannot predict how lift coefficients will change with camber, so the proper deflection for the inboard flaps will need to be determined experimentally. Now I just need to save up to buy all the new carbon required.

I have a rough estimate of how the inboard flaps need to be coupled to the outboard elevons for the first flight. Based on a 20 degree deflection of the elevons, the flaps should travel +0.6 times the elevons' deflections. This relationship should only hold true for deflections close to zero (read: <40 deg), and I will need to redo them with the deflections at stall determined experimentally.

Using Cl/alpha data from airfoiltools.com of a ~flat bottom foil and a similar one with a relatively sharp camber increase at 70% chord (read: normal airfoil vs. airfoil with flap deflected)...Continue Reading
Posted by RPM314 | Feb 05, 2015 @ 08:57 PM | 2,943 Views
I am now the proud owner of some sick Nano QX skills as well as some FPV gear, so it is time to kick things up about 300 notches. Since this is my first multicopter build, I will be basing it mostly on someone else's design; David Windestal's tricopter 2.5. I will be making my own gusset plates from light ply instead of G10 fiberglass, as well as my own yaw mech. I will be using his construction style for a vibration isolation camera/battery tray, and friction stop folding front arms.
The FPV camera will velcro to the front of the battery tray, and the VRx will attach to the rear landing skid. (people always put a new skid on the copter for this - don't see why) I will be running it off of the usual turnigy 2200mAh 3s 20C battery, though current draw at max RPM will be ~24C. I will not be racing with this and the flight controller limits it to 90% RPM anyway, so I think it will be fine. I can use the parallel harnesses from the falcon mk. 6 to remedy this, though. I am also getting a properly hot soldering iron to do the power harness right, and a prop balancer as an investment to compensate for the fact that I am buying cheapo props.

Parts list: KK2.1.5 flight board, Afro 20A ESC's, TGY 5A UBEC to power the M2-8 rail, TGY D2836/11 750Kv motors (functionally equivalent to DT750's), Corona 939MG digital yaw servo, cheap HK 11x4.7 props (also in the green and CW variety), a 5mm motor shaft for the yaw axle.
Misc: 600mm servo extensions, twisted Rx-flight board male to...Continue Reading
Posted by RPM314 | Jan 28, 2015 @ 10:48 PM | 3,267 Views
Hi, all. After a month and a half of backorder delays, the Quanum FPV bundle set finally arrived. This is my first FPV equipment, so I cannot give a competent review but I can give my impressions on the setup and construction from an FPV noob's perspective - the intended market of HK for this product.
Please note that before the hat comes in, the build is the same as HobbyKing's build video, so you can refer to that if you prefer.
I also got a wide angle lens, is fits the camera perfectly and has maybe 20-30 degrees of FoV more than the stock lens.
The camera's resolution is not very high, but it is serviceable. You cannot read the titles of books at 5 meters, but you can still see there are books there. It seems to handle contrasting light conditions pretty well, I was able to see the stuff inside my apartment along with the glare around the windows at about the same lighting level. When I pointed it at a light fixture then down at the floor there was a 1~1.5 second delay before is adjusted to the new brightness level, so that means seamless transitions from looking at the sun to the ground will not happen. However, all this simple imaging power (or lack of) has an upside:
The setup has very low latency, I was not able to see any by moving my hand around in front of the camera. I pointed the camera at the screen to create an infinite loop, and it is possible to see the delay travel down to infinity that way, but the fact remains that the delay from camera to screen is...Continue Reading
Posted by RPM314 | Jan 10, 2015 @ 09:09 AM | 2,006 Views
The first airframe took a big hit, distributed all across the front of the plane. The damage is not localized, so everything just kind of fell apart, but the individual components are perfectly intact. Time to build a new airframe. I will be putting a few pictures up, but mostly I'm going to try to put the whole process - design to flight - in a big video which will come when the plane is done. I want to make a time lapse tutorial for prospective scratchbuilders to show it is not some magic. Also to show that flying wings are very simple to construct (I have seen way to many people intimidated by the idea of building a wing because they think it harder than a conventional plane).

1/9: Design segment of the video is finished
1/10: Parts ordered. Only a couple carbon rods for the elevons are needed, so construction can go on.
1/11: Most components drawn out on foam, but the camera is not cooperating. I will bring in Peter next weekend to get the cam working.
2/22: The clips up to the wing formers are processed, all foam pieces are cut out, main wing sections are taped up.

3/26: After completing the energy unit in physics class, I can safely say there is room in the motor's capacity for a speed increase with a 6x5.5 prop. Up to 140-150kph, perhaps

In light of new information, this design is outdated as a maximum performance sport plane. Work on the Prandtl based wing has already begun, the Mk. 5 will still have a place at the table for its aerobatic ability.
Posted by RPM314 | Dec 29, 2014 @ 10:25 PM | 1,941 Views
Hi, all. To teach myself how to fly multirotors as a prelude to hopefully building one, I followed the advice of many people more knowledgeable than me and got a nano qx. I am very impressed by the frame itself, it is stiff in the directions it needs to be but incredibly flexible in all others, I do not think it is possible to break it under its own power. I am complete rubbish at flying it, of course, but given how zippy it is at low rates and its available power, I can tell it has the potential to become sportier to suit one's increasing skill.
They say it can be flown in a small living room and they are absolutely right. If you are good at hovering, you can spot land on really any surface. I have been getting about 5 minute flight times out of it, granted they are with my old 1s 150mAh batteries from the micro P-51 Mustang. The one battery it came with seems to have 6-7 minutes in it. I love the USB charger they came up with, it saves a fortune on AA's and in super convenient.
One important note - if you are serious about multirotors you will be flying it in non-autolevel mode (agility mode). I have never heard of anyone else having this problem, nor has Horizon's customer service, but if in agility mode you inexplicably have no lateral control with the right stick (no pitch or roll) but you do have yaw and throttle, you need to keep the flaps switch in the down (1) position, not toggle it back up after the quad's light goes red. Took me a good while to figure that one...Continue Reading
Posted by RPM314 | Dec 14, 2014 @ 03:20 PM | 2,338 Views
Not a replacement for the Mk.V or necessarily a better machine, just designed for a different job. FPV, BABY.
That's right, Imma get me some FPV gear by year's end. To accommodate it, I'm making a 54" (1370mm) wing with a turnigy d2838/8 (1100Kv) motor with a 9x6 (230x155mm) prop. I want to make a simpler kind of craft that is a bit more easily replaceable should it get lost out somewhere. I'll also probably set up a parallel harness for batteries to get some more duration. Lots of wing area, lots of power, lots of battery capacity, a thick wing root, and a beefy motor means a floaty, heavy lift, long duration, stable FPV platform. Hopefully. We'll see how that turns out.
I also want to make it foldable to take in the car on vacation and surf down the Appalachians or something, get some nice cliff diving videos and such. That presents the challenge of making a removable motor mount, and I believe I have an adequate solution, but of course that will still be trial and error.

12/13: All foam pieces are cut out, fins are taped up and ready to go, the wings are taped up and scored for folding, the formers are glued together. Note - when you use reinforcement tape at the LE under the packing tape to provide tensile strength so the foam doesn't crack, make sure that has SIMILAR ADHESIVE PROPERTIES to the packing tape. I used cheap duct tape that slides a bit more easily, and messed it up something awful.

1/3/15: The elevons are sanded and beveled into shape, and have...Continue Reading
Posted by RPM314 | Dec 02, 2014 @ 05:33 AM | 1,940 Views
A little late on the processing, but here's a couple more:

Some nice air video spliced with ground video courtesy of Mark, it looks really cool.

Falcon Mk.V - Thrill Factor (6 min 8 sec)

A compilation of 3 flights from Peter's HawkSky, managed to get a little ground footage in there.

...Continue Reading
Posted by RPM314 | Nov 17, 2014 @ 06:59 PM | 2,015 Views
Some more of my wingman Peter flying his Dynam Hawksky around the field, climbing and diving around.

Peter's HawkSky - Pushing It (3 min 39 sec)

Posted by RPM314 | Nov 15, 2014 @ 10:20 PM | 2,242 Views
I binge watched Free Bird by Lynyrd Skynyrd so I could sync the flight to the song. This is the Falcon Mk.V with Peter's Mobius action cam (wide angle lens) stuck into the right air intake, and shows the plane's amazing ability as both a motorglider and a pylon racer. Some good climb and glide segments, then 5 minutes of carving sweeps around the field, low passes, and lots of loops and stuff.
This was filmed on 11/15/14 at the Remote Control Society of Marine Park, it was one of those days where it is cold but the air is perfectly clear, so the high altitude video is stunning. There is another video from that day, I should have it processed by tomorrow.

Falcon Mk.V - Free as a Bird (10 min 51 sec)

Posted by RPM314 | Nov 04, 2014 @ 06:36 PM | 2,669 Views
Hi, all. Made a cutting edge, super lightweight, crash resistant mounting system for future mobuis action cam flights. This is some real next level stuff, super streamlined and engineered for VICTORY. The world has never seen nor will ever see again this degree of prescision....
Ok it's a mobius shaped box with tape covering. It has little spacers inside so it doesn't push the buttons. The top panel comes off so you can put the camera in it. It's made of foam. That's about it.
Posted by RPM314 | Oct 30, 2014 @ 08:13 PM | 2,334 Views
Flying at RCSMP in October. My wingman Peter McGyvered a Mobius action cam to his old HawkSky and gives us a good view of the field. The Falcon Mk. V also makes a few guest appearances.

HawkSky with onboard Mobius at RCSMP (3 min 54 sec)

Posted by RPM314 | Oct 18, 2014 @ 05:37 PM | 2,010 Views
The Buzzard's motor has been rendered inoperable because of its tractor configuration and proximity to the ground upon landing (read: front motor dun got messed up when I landed). The new aircraft using the 2s power system will be something I have wanted to try for a while; a slightly forward swept flying wing with strakes. It will have a small fuselage pod and twin vertical fins, pusher prop, and a 4-flap wing ('cuz I have way too many 5g servos to use). I might try out 7x6 props on it instead of 8x4's, since this should be more controllable at high speeds than the Buzzard.
When drawing it out in sketchup, I figured I couldn't move the fins back far enough behind the CG for them to be super effective, so I thought I might need rudders on it to stay coordinated. Then I thought only needs 1 servo+makes use of ability to spin out+also gives yaw control=THRUST VECTORING YAW. So I'm going to try my hand at making a hinging motor mount.

10/19: All parts are cut out, but nothing is taped. Spars are embedded in the wing and the KF steps are in place.
10/21: Flaps are beveled, and I made a torsion bar for the elevators.
10/24: Control surfaces and the wing are taped up, the fuse sides are glued in and the fuse bottom is attached to those. All servos are glued in place and connections to the Rx are hooked up.
10/26: Elevators are connected, the TV yaw block is constructed, the top wall of the fuse is shaped to accommodate all the stuff under it
11/2: The fuse top is installed,...Continue Reading
Posted by RPM314 | May 26, 2014 @ 09:47 PM | 2,652 Views
Note to self-think of better name for airboat than "Airboat"
Done- "Drake", a male duck (waterfowl-get it? yeah).

Same hull design as the last one, but this time it is made of MPF. The fins at the back will also be higher to capture more of the propwash with the rudders.

5/26: Frame and lower hull are complete.
6/19: rudders are done, the motor is mounted, and the deck is on. The receivers arrived, so this ship is ready to sail.
6/29: Wind flipped it over, will dry the parts out overnight. If the ESC still works, I will try it in the Falcon mk.V to see if it gets it working.
6/30: ESC still works

Status: Gutted for parts
Posted by RPM314 | May 11, 2014 @ 07:23 PM | 3,984 Views
My take on the FnF, which is a variation of the Funbat, which is based on.... You get the idea. 32" span, KFm2 airfoil, 1700Kv BW motor, 10A ESC, and 950mAh 2 cell battery. I hope to fly streamer combat with it against other guys at the field.
This is a quick and dirty build, without much attention to detail. In fact, I believe I will be able to complete it without sanding anything, which is a relief after all the shaped wingtips on the Falcon craft.

Finally, some progress to report. I finally got the wing to cooperate, it is folded over to make the step neatly now.

5/24: PARTS, GLORIOUS PARTS. A whole bunch of 2s stuff came in from strongrcmotors.com, and I am ready to build. Servos are glued in, components are aligned to balance the thing properly, and the ESC has a little cooling window in the side of the fuse to peek out of. Still need some receivers, and some very small screws to mount the motor.

5/26: The ship is as far along as it will get without the receiver: once I order those I can attach the fuse.

6/19: The receivers arrived (FINALLY), so the fuse is now attached, the control linkages are set up, and this bird is ready to fly.

6/29: Maiden went well, it handles the wind nicely. It handles very well, responsive yet floaty. I need to rebuild the motor mount and resolder a motor lead, though.

7/2: Repairs are complete, it is ready to go again.

7/12: Flew it in real streamer combat, it is excellent at the sport.

Status:...Continue Reading
Posted by RPM314 | Mar 21, 2014 @ 11:20 PM | 3,248 Views
Given that the structural insufficiency of MPF in the glider type wings renders the fuselage pod useless, and that I slammed the Mk.IV into blacktop pretty hard, I am making a new bird that gets back to the roots: a pure, solid wing. No bells and whistles in the layout, it will consist of a swept, tapered wing with washout, with small laminated wingtips and solid fins, and a hatch in the center. There will also be vortex generators near the wingtips, and the gear from the Mk.IV will be transferred over.
3/22: All parts are cut out, the wings are taped up and have the formers, but do not have the full compliment of carbon or the servos. Lots of sanding and taping still need to be done.
3/26: The interior of the wings are done, the fins and elevons have been sanded, and sanding has begun on the wingtips.All those parts still need to be taped over before they can be installed.
3/28: The wings are closed up and washed out and the wingtips and fins are finished and attached.
3/30: Elevons are finished and attached, ventilation has been taken care of and a battery hatch has been installed.
4/2: Motor mount is complete, but I will not mount the motor until everything else is done so I can use it to balance the plane.
4/5: Elevons now have 1/16" balsa on the underside for stiffness. Control linkages are set up and functioning, the plane is balanced at 10% MAC, the motor is mounted, stripes are on the bottom of the wingtips, and the vortex generators are in place. All...Continue Reading
Posted by RPM314 | Feb 23, 2014 @ 04:52 PM | 2,954 Views
Hi, all. After ealizing that the gear from the Petrel was lying around being useless, I cobbled together a quick 24" wing from MPF.
The root chord is 6.25", the tip chord it 4.25", and the sweep distance is 6", with a kfm2 airfoil. It has 2 5g servos directly linked to the elevons (no pushrods), a 3A turnigy UBEC (smallest one I had), an orangerx 610 (I think) and a 2s 280mAh lipo battery. AUW is about 2oz, which is a bit heavy. It needs to be scaled up to about 30" or 36" to really float, but as is it would make a good sloper if I had a place to slope.
The maiden was today, and it flies nicely, if a bit fast for a glider. I rigged a rubber bad to hook into my friend's plane's cargo bay door, so the plane was carried on its underside. When the door was opened, the end of the rubber band came loose and the glider was released. Big cheers from all over the flying field.

Status: Cannibalized
Posted by RPM314 | Feb 17, 2014 @ 06:03 PM | 3,530 Views
Hi, all. I decided to take a crack at the hydrofoam, with my own twist of course. It will be made of MPF, colored packing tape, foam tac, and some hot glue. For the electronics, there will be an AR610 receiver, MG90S servos x3, HK 30A ESC, turnigy D2826-10 motor (1400Kv) swinging an 8x4 prop, and 3s 2200mAh batteries. I call it "Raider" because of the front halve's resemblence to a Cylon Raider fro Battlestar Galactica.
It is pretty similar to the design found at Parkjets.com, although I did not intend to make the dimensions as similar as they are. The main difference is that the prop is mounted on the tail like an airboat instead of on a pylon over the ventral pod. I did this to avoid ground and water strikes more, and because I could not come up with a ventral mounting system that did not look like garbage.
Overall length is 26", overall width is 16". There is about 1.5 square feet of lifting area, and I expect AUW to be around 16oz. It will not be 3D, but it will still be very sporty. With only red and black tape to work with, I believe I came up with a neat trim scheme, yes?
If anyone wants to reproduce it, reply to this post and I can send you the complete model and parts template.

2/18: Airframe awaits final assembly and fitting of gear.
2/19: The Rx recovered from the lightning is busted after all, so I pulled the one from the falcon for the job. The plane is complete!
2/23: Tried to fly it today, no such luck. It feels nose heavy on the...Continue Reading
Posted by RPM314 | Dec 30, 2013 @ 05:38 PM | 3,137 Views
The next iteration of the Falcon is very different from the previous ones mainly in that it is made of MPF instead of dollar tree foam. It also incorporates the wingtips from the Lightning and a similar trim scheme. There is also 3 degrees of washout to fight tip stalling, which was a serious problem on the previous models, and the wings have a taper ratio of about 2/3. Power is a Turnigy 2826-06, 2200mAh battery, and a 30A HK ESC. There are two sets of wings, a sporty and glider one, which plug into the fuselage instead of being strapped on top. As such, the wing halves are kept separate instead of hinged.

12/30: Plans are drawn out on the foam.
12/31: Parts are cut out, the sport wing has been tape covered and the spacer attached.
1/1: One of the sport wings is nearly finished, needing only a control linkage.
1/3: Glider wings are up to the servo installation stage, and the fuselage tube is ready to install equipment in.
1/5: Both sets of wings are complete and the electronics are dry fitted into the fuselage for balance testing.
1/9: The correct mounting points have been identified, still working on the actual mounting.
1/11: Mounting is done, fuselage is completed, control linkages are complete, and system check have been run. This bird is now ready do fly, maiden will most likely be this Monday.
1/20: The weather forecasters were highly inaccurate about the wind speeds, they said 12 mph and it was really twice that. The glider wing is dented and the mounting tabs must...Continue Reading
Posted by RPM314 | Aug 31, 2013 @ 09:50 AM | 3,916 Views
The cheesily named Greased Lightning will be derived from the Polaris, with a few important changes. First, it will not be a seaplane since I do not fly off of water, so some design elements regarding waterproofing can be left out for simplicity. It will still be able to taxi/take off/land on land though. Second, it will be much more efficient. The Polaris also had a low aspect ratio flat plate wing. It is simple and good for extreme high alpha and whatnot, but it is not very efficient. Cut the power and it drops like a rock, take a sharp turn and you lose half your speed. GL will have an armin airfoil wing of about 10% thickness (very thin) with large strakes to preserve the high alpha ability of the original polaris. The aspect ratio will be about 6, so it will glide well and keep speed in turns. Power will be a turnigy d2826-06 spinning a 6x4 and a 25A esc. Wingspan is 42" (~105cm) and length is 33" (~84cm).

Here are the dimensions for anyone who wants to replicate it:
The wing is made by taking a 30" section of 5" chord armin wing and cutting it in half to create 2 15" sections. These are swept 15 degrees at the root only, the tips are kept square. The wingtips are quarter circles with a radius of 6.5". The ailerons have a chord of 1.5". The strakes are triangles extending 6.5" forward and 6.5" along the leading edge of the wing. It is formed from 2 opposed trianlges with a rectangular area 1/2" wide between them (...Continue Reading
Posted by RPM314 | Aug 12, 2013 @ 08:53 PM | 4,117 Views
A 48" (1.2m) glider made of DTFB as usual. Gear is an AR600, a turnigy 3A BEC, a 280mAh 2s lipo, and 5g carbon gears. It also has an on/off switch (Fancy!) It is of conventional layout with flaperons.
The wing has 2x 20" sections of armin wing with a 4.5" chord. Wingtips are 4 layers of laminated foam sanded down to shape, with a 4" span each. Flaperons are 2" at the root and 1 1/8" at the tip, extending from the elliptical wingtips to 1" from the fuselage. It has a 5/16" wooden main spar of 42" span, a 32" span 3mm carbon spar near the top of the wing (since the top tends to compress under load), and a 16" span carbon spar near the bottom.
The horizontal stab is 13" in span, has a root chord of 4 3/4" and a tip chord of 3 1/4". The vertical stab is 6" high, has a root chord of 4 3/4" and a tip chord of 2 1/4". It also has a 45 degree bevel to allow for elevator travel. Both have a straight trailing edge. The elevator has a chord of 1 1/4". The rudder has a root chord of 1 7/8" and a tip chord of 1 1/8". Both have aerodynamic balances extending 7/8" forward and are 7/8" wide. Each has a 3mm carbon spar and they are affixed to each other by a plastic gift card bent at a right angle, mounted internally.The assembly is hot glued to the fuselage such that the elevator hinge line is at the end of the fuselage.
The fuselage is a 40" long square tube (composed of...Continue Reading