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Posted by A Useless Geek | Feb 24, 2014 @ 10:23 PM | 2,098 Views
So, last summer my HK Mini quad PNP came out of the box with a KK2 board on it and all the ESCs soldered up, yada yada. The very first flight I hovered it over the driveway for a bit then tried a little rocket. I mean, just a little rocket, like I wanted it to shoot up a meter or so. The durn thing went three meters into the air and flipped over about six times before coming down hard in my neighbor's front yard. Broke one arm off at the end. Total flight time: about ten seconds.

The damage revealed some outstanding weaknesses in the HK design (which I presume they just bought off of somebody else, but who knows). For one thing, the arms are not structurally sound out at the ends where the motors mount. There is no longitudinal bracing for the arm after the point where the ESC solders on. The fiberglass of the circuit board is neither strong enough nor flexible enough to take the stresses of a less-than-perfect return to Earth.

In order to fix my unit I had to do some surgery to the outboard end of the arm and attach a pile of CF strip and square tube to make the arm both strong and stiff enough to handle the stresses of a quad. I scraped away some solder mask on the bottom side of the board and made sure the top side was ready to accept CA. Then I tacked on some CF strips on the outside of the vertical portion of the arm. Once I had the arm end positioned properly I added some square tubes on the inside. The whole mess got a substantial blast of thick CA to bind everything together and form a solid surface to spread out stresses.

This thing works now, but I'm not really happy with the performance. My MultiWii quads are outperforming it right now. Maybe I just need to do some more tuning. Whatever.
Posted by A Useless Geek | Nov 05, 2013 @ 11:23 PM | 2,294 Views
So, now I've got a UDI 816 micro, two WL Toys V929s and a Syma X1, and three scratchbuilts. It's getting crowded in Quadland, Illinois. Now I need to start ordering props in bulk from Banggood, HK, etc. I go through a lot of them.
Posted by A Useless Geek | Oct 30, 2013 @ 09:15 AM | 2,533 Views
Okay, so my littlest scratch quad wasn't behaving all that well. I started out with a HK I86 board running four Turnigy 1811-2000 10 gram motors on stock Plush 6A ESCs. The thing would spin, and roll over, and generally play dead. Not phun.

Then I switched to a HK MultiWii control board.

Shazam! Suddenly the Little Quad was a docile, easy to fly package, almost like those commercial brushed minis. However, the Little has a bunch more performance, like a WLToys V929 or Syma X1 on steroids or cocaine or something. I am very happy. This gives me a transitional quad on which to learn more advanced flying techniques without the expense and hassle of constantly fixing a bigger quad with more mass, more expensive props, etc. Verrrrry nice.

-- Construction --
(4) Turnigy 1811-2000 motors
(4) Plush 6A ESCs
HK MultiWii flight control board
OrangeRX R615 Spektrum-protocol receiver
HK 5x3 counter-rotating prop set, red
HK 5x3 counter-rotating prop set, black
Custom-built frameset, with tie-wrap landing skids

-- Specage --
Dry weight so far: 125 grams
AUW with nano-tech 850 2S 25C: 174 grams
Shaft-to-shaft: 270 mm
Flight time: 6 mins or so, maybe longer -- I keep crashing and doing silly stuff
Posted by A Useless Geek | Aug 15, 2013 @ 07:39 PM | 3,822 Views
So, I got a FlySky module for my Turnigy 9XR, the radio I am using to replace my Spektrum DX7s pile of scrap (POS). The 9XR is a nine channel radio with a whole lot more control capability than the seven channel DX7s could ever pretend to have, and even more than the DX8 claims.

The only thing is, in order to get the 9XR to properly control my Syma X1 mini quad I had to reassign the channels to make the 9XR look like an old 72 MHz FM radio. If you are using a 9XR to run a quad set your radio up as follows:

Page 5 [MIXER]
CH1 XXX% AIL
CH2 XXX% ELE
CH3 XXX% THR
CH4 XXX% RUD

Page 11 [TEMPLATES]
Channel Order: AETR

After that yer quad should respond properly. You may still have to play with servo reversing (had to reverse elevator on mine) but it will be pretty obvious. Also, on my Syma I put the mixer settings all the way up to 125% to try getting more control out of the quad, but it only has so much.
Posted by A Useless Geek | Feb 22, 2013 @ 01:24 PM | 3,939 Views
A lot of people have asked me about plans for the Longhorn. Well, I ain't gots no plans because I'm a Lazy Bumģ. However, I have some images to show the dimensions and some instruction on how to build one:

http://www.rcgroups.com/forums/showt...0#post18591223

I've made some changes to the way I assemble these planes now. One thing is I eliminated the fuselage spar in the back by extending the horizontal stab with a strake. This spreads the stresses out and prevents the fuse from breaking without adding the mass of a CF or spruce spar. Another change is to go back to the laminated fuselage made from two pieces of 6mm foam with a bit of sheer nylon curtain material in between.

Of course, this depends on using the right material: Model Plane Foam. This stuff has the exact right properties to build a plane that's flexible enough to bend without breaking, but stiff enough to support the kind of crazy performance for which the Longhorn is known.

Iíve discovered a lot of phunky properties of this plane, but havenít recorded a lot of my experiences yet. Let me take some time to sort this good stuff out and Iíll eventually add everthing Iíve found to this thread. In the mean time, build a Longhorn for yer own bad sef and make your own discoveries!
Posted by A Useless Geek | Feb 22, 2013 @ 11:04 AM | 3,609 Views
So, the Barnstormers had a Fun Fly out at the dome last night, with the contest being a Balloon Break. In this case we used balloons suspended from a catenary pole held aloft between two end poles. Lots of people flying all kinds of aircraft trying to get between the end poles first, under the catenary second, and targeting the balloons last. More than a few collisions between folks going for the same balloon. General hilarity ensued. I had more phun than I've had in months, and laughed hard enough to split a seam.

But poor ol' #4 was the victim in all this frivolity. I guess 176 qualified flights (minimum five minutes, contiguous, not interrupted by damaging crash requiring other than a prop change) was enough for that airframe. I got clobbered by multiple aircraft, bounced off the poles a few times, and only popped two or three balloons. Oh, well.

My next Longhorn will be made from MPF, of course. This one will have some fairly high dihedral to promote tight spirals and wicked turning response. I still have one old unit made from PBIII and Pink, but that one doesn't get used very often. I'm thinking of giving it away.
Posted by A Useless Geek | Feb 12, 2013 @ 03:35 AM | 3,855 Views
So, I'm thinking about a stupidly fast foam plane for the summer. I've seen folks going pretty fast with Multiplex Funjets and such, but my target is 300 KPH, about 186 MPH. I'm not interested in any kind of hotliner, since those things just look too ugly to me. I want to build -- or at least assemble -- something jettery with a single motor and a single prop. Not an EDF, not a turbine. A prop.

It's fairly easy to get small stuff to go relatively fast. I built a perversion of a Pinkstar with a Blue Wonder 3000kV motor that does in the 60 MPH range (haven't instrumented it yet), and that's not even trying very hard. (60 MPH doesn't seem very fast outside, but in the golf dome it's at the limit of my abilities.) Lots of folks have pushed scratch Funjet clones of various types to the 200-250 KPH range. What does it take to get over the cliff and hit 300?

Suggestions welcome.
Posted by A Useless Geek | Nov 08, 2012 @ 03:36 PM | 3,984 Views
Okay, so I've been playing with that WLToys ICopter for a while now. Yesterday I managed to "land" the thing upside down on the driveway hard enough to crack the bug shell in half. Uh, oh. Gonna hafta add some protection to the board on the top side now.

But I've got enough quad time under my belt that I want to move up to something a little bigger and better. To that end I have a few multi frames that I'm building up. Only two flight controllers right now, but that'll change with my next Hobby King order. Of everything else I have plenty, but the flight management is hard to come by.

The three quads are a Holybro Hobby X-230, a Hobby King CF Talon, and a Hobby King fiberglass X666. The tri is from Scott Hall, aka Hall Effects. [cough]

(As a side note, those two frames are only modified by Hobby King. They are not the OEM.)

We'll see how this goes.
Posted by A Useless Geek | Oct 22, 2012 @ 05:25 PM | 4,081 Views
'Nuff said.
Posted by A Useless Geek | Sep 15, 2012 @ 01:12 AM | 4,412 Views
sr71fan, one of my R/C heroes, has been flying a lot of symmetricals lately. Now, Gary can fly anything and make it look like phun regardless of how well it flies, but these symmetrical jobs have always appealed to me anyhow. Maybe it's the rocket-like shape that harkens back to my rocket daze. Whatever. I love the cool presentation of these planes; the way they look the same along any axis; and the way they can flip-flop from up to down to sideways and just cruise along regardless. Far too cool.

So, I started my own symmetrical build last year. [cough] Haven't finished it yet, but at least it looks like something that's actually in process. Note that this plane got started before MPF was available, so it's made from FFF and not Adams. The next one for sure, eh?
Posted by A Useless Geek | Jun 13, 2012 @ 01:47 PM | 4,571 Views
So, I realized that my box of sub-100 gram motors was getting pretty full. Okay, some of these are committed to upcoming planes, both mine and others', but the bulk of them aren't dedicated to anything in particular. Keep in mind that this is only about four years' accumulation. What's going to happen over the next twenty?
Posted by A Useless Geek | Jun 13, 2012 @ 01:02 PM | 4,703 Views
So, I finally finished my first plane made exclusively from Adams material through Model Plane Foam. The plane came out as 154 grams dry, right in line with the rest of them. I went back to a doubled-up fuselage with a piece of shear nylon curtain fabric in between the two layers. Instead of using a CF or bamboo brace in the back I went with a strake on the horizontal stab. We'll see how this one holds up.

I made a couple of boo-boos when constructing this plane, so it isn't as great as the rest of them. For instance, when using a flame thrower (cigarette lighter) to shrink the tubing for the control rod ends I managed to melt some foam. Twice. Don't accuse me of being overly smart.

But even with the screwups in construction and layout the plane performs well. It's a Longhorn, and it's kinda hard to make one of these not perform well.
Posted by A Useless Geek | Feb 10, 2012 @ 11:23 AM | 5,122 Views
I finally got my Hobby King Quattro to add to a couple of Accucell-6s that I already had. (The older one had a phunky phan, so I took the cover off for cooling.) Now I can charge six packs at a time with fully programmable convenience. I also have a handful of fixed-current chargers that I can use for some other packs, but those aren't very accurate nor reliable. 'Sokay, six at a time is prolly all I'll need. Heh.
Posted by A Useless Geek | Dec 29, 2011 @ 02:11 PM | 5,363 Views
Yeah, well, I keep shifting around the planes hanging on my wall. Planes come and go as they get built, go downstairs for repair, get destroyed, go on a long-term storage shelf, or whatever.

So it goes.
Posted by A Useless Geek | Oct 22, 2011 @ 02:12 PM | 5,843 Views
Well, okay, I do seem to make an awful lot of these "loaner" planes, but I keep running into people who need something like this to learn how to fly. This is something I whipped together from cutoffs from other planes. I wanted to make something pretty light without resorting to "exotic" parts and materials.

To that end I used standard 6 mm Pink, 14.5 mm Pink Foamular (the old, light, soft stuff) for the fuse, a bamboo shish kebab skewer to keep the back end from breaking off, and some other standard junk. The light ply for the motor mount plate and backing plate are cutoffs from bigger planes. The piece of EPP for the motor shock mount is just plain scrap, it's so small. I heated up some used Velcro to make it stick to various places on the airframe, but used new stuff for the battery mount. 0.032" piano wire through coffee stirs forms the control setup.

The tail surfaces are held on with Beacon Fabri-Tac. The main wing is held together with foamed-up yellow Gorilla Glue in the center. The wing is held to the fuse with toothpicks and CA. The bottom of the fuse is taped with 3M Extreme tape to keep it stiff and to prevent landing rash. (The 1/2" Pink stuff is really, really soft.)

This plane came out a little heavier than I really wanted, but that's what happens when you use standard materials rather than 3 mm Depron, CF, and other stuff that costs a bunch of money. I'm trying to get some building techniques down for the use of those...Continue Reading
Posted by A Useless Geek | Sep 27, 2011 @ 01:45 PM | 6,628 Views
So, I was cutting out wings for a pile of Pinkstars and ended up with these two cutoffs that looked like moth wings. Instant "brain" (as I like to call it) storm: a slow flyer that uses big, fat wings. How original. Here's what I ended up with:

Span: 880 mm
O/A length: 784 mm
Mass: 168 grams
Motor: Turnigy 2204-14T (19 gram, 1400 KV)
Prop: GWS 8x4.3 EP slow (EP-0843)
ESC: SS 8A
Servos: hexTronik HXT500 x 2
Rx: OrangeRX 6 channel, minus useless plastic casket dead weight

The surfaces are almost completely 6 mm Dow Protection Board III. The fuse is 1/2" (actually 14 mm) Pink Foamular. 3M Extreme tape holds the whole airplane together, particularly in the back where I used no spar embedded in the fuse and paid the price for that. I actually broke the plane in half by holding it up from the tail surfaces. After using foamed-up yellow Gorilla Glue to put it back together I added tape to hold the tail end stiffly into place. Duh!

So, now I've got another plane to loan out to people trying to learn to fly. I'm not really happy with the stall characteristics of this plane, so I can do one of two things to fix that; either add a KFm2 step on the top side to make it fly slower and have gentler stall, or cut the wings back to a Skinny Boy configuration (there's plenty of meat on the wings to achieve that shape) and have the plane actually fly a little bit faster, but with easier handling characteristics. I don't know which approach I prefer. In either case I ain't gonna be the one flying this plane a whole lot.
Posted by A Useless Geek | Jun 05, 2011 @ 10:18 AM | 6,189 Views
This thread may get a lot of traffic, or none. Who knows? I'll keep updating as I get more photos made of assemblies on which I'm working.

To start with, let's take a look at how I build wing assemblies for the Skinny Boy, Eluder, Longhorn, Lunatic, etc. These are flat pan wings with a dihedral in the middle. The wing roots are cut at an angle so that they meet in a vertical line when the halves are put together. The underside of the assembly gets support from balsa trailing edge wedges cut down to size. After the wedges are put in place the entire underside of the wing root is sanded flat to meet with the flat top of the airframe.

Put the wings top down on a flat surface, then use blue tape down the centerline to hold the assembly together. Flip the wing over and apply puffed up Gorilla Glue to the seam. Weigh down one wing and prop the other one and the correct angle. Prevent the GG from puffing up too much on the top side by applying blue painter's tape. (The cat isn't necessary, but may help relieve tension.) The extra GG puff on the top side of the wing supports the wing during high G maneuvering.

Balsa trailing edge wedges are available at the LHS in long strips. Use a slitter to cut them down to size. You only need enough width to make contact with the top of the airframe, typically 10-16mm wide depending on what you are using. Glue the wedges along the underside of the center seam. The thin edge goes toward the center. The idea is to make a flat surface so that you can glue the wing to the airframe without gaps.

After the glue is cured you can sand the underside of the wing root to get a completely flat surface that can then be glued to the top of the airframe. You gots a basic airplane!
Posted by A Useless Geek | Jun 03, 2011 @ 02:25 PM | 6,180 Views
So, I've sorta fallen down on the really fast park jets the last year or so. The indoor/outdoor sport planes have been so much phun that I've ignored the realm of fast park jets almost completely. A couple of my fast projects are coming back to life now that I have everything (except batteries) to finish them.

I considered doing the Multiplex Blue Shark TwinJet first, since it already has servos mounted and such, but I know how much effort will go into getting the motors aligned on that beast. Instead I'll do the Electrifly Firebat first because it's a little simpler and has some features I want to mess with anyway.

My plan is to enhance the maneuverability with my own stiff balsa elevons, separately-controlled anhedral canards, and linked rudders. Needless to say it will be brushless and carbon fiber supported. I'm not going to go nuts with power; I figure 500 watts or so ought to get it moving pretty good. Maybe a little more.

The naked airframe as shown is at 193 grams, so it won't be a lightweight. (By comparison, a good Longhorn is 180 grams all up.) I'm not really worried about weight at this point because I know I can get it to fly fine with the amount of power I have in the motor box. I am thinking I can get this planes put together at 500 grams or maybe a shade less. And that's with an 80 gram motor, so it ought to scoot pretty good.

Stay tuned as this one comes together.

Later:

Okay, so I decided to try something a little less expensive and maybe...Continue Reading
Posted by A Useless Geek | May 31, 2011 @ 11:12 AM | 6,615 Views
So, I end up with a lot of these planes that kinda suck wind. Sure, everybody builds a stinker now and then, but how long are you gonna stick with a plane that obviously doesn't perform? A couple of years ago I was plowing through planes at a rate of two or more per week. If I hit on a plane that smacked I tried working with it for a little bit, but then I'd scrap it if it didn't get any better.

Why is it now that I can't seem to let go of any of these lousy planes? Take that Son of Blue Star, for instance. The first pass wasn't horrible, but it wasn't very good, either. I kept hacking at it and hacking at it because the plane showed some glimmer of promise, even though my changes weren't getting the kind of improvement I wanted to see. Duh! The plane eventually mutated into something completely unrecognizable from the original, and I scrapped it because it was too heavy.

Now I have this Pinkstar thing, which was supposed to be an hour and a half project completed just ahead of a club meeting a few months ago. Yet Another example of a plane that I just can't seem to get rid of. I have massaged and mutated this poor thing so much that I can't tell any more what was there originally and what was added later. It's been flown and smashed up so much that it's mostly repairs and add-ons now, I think. Why can't I just let go?

Grrr!

Later:

Well, the first version of the Pinkstar certainly wasn't very good. In fact, that plane flew better inverted than it did right...Continue Reading
Posted by A Useless Geek | Apr 30, 2011 @ 02:41 PM | 6,488 Views
So, the 2010-11 indoor season out at White Pines Golf Dome is ending tonight. I didn't do my shift last night or last week because I had an emergency appendectomy last Friday afternoon. That means I missed the Swap 'Til You Drop event a week ago today, also. That's really too bad, because I was looking forward to getting rid of some indoor stuff and maybe picking up a couple of outdoor planes for the summer. Oh, well.

I'll swing by the golf dome for a while tonight, but I ain't staying until 01:00 in the morning. Perhaps I'll have a new plane to try out. Not expecting a real big crowd; the last couple of weeks are usually pretty dry out at the dome. Everybody is getting ready for the summer and the indoor stuff is mostly finding its way back on to the upper shelves.

A week from tomorrow (Mother's Day) is the swap meet out at Lake Barrington Field House. Perhaps I can move some of the excess indoor stuff that didn't make it to Swap 'Til You Drop. Sure hope so, because this surgery stuff is going to cost more than my current net worth. Heh.