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Archive for December, 2010
Posted by A Useless Geek | Dec 09, 2010 @ 10:19 PM | 7,894 Views
Anybody else have a DX7 that has given you the nice "BACKUP ERROR" message? Isn't that a treat?

The way the stoopid DX7 works if there is a brief -- like, measured in tens of milliseconds -- disruption of power then the darn thing tries to write a bunch of data to the FLASH. If the power comes back up before that write cycle completes then the radio trashes a bunch of FLASH data and goes in the tank.

If the FLASH contents take a complete header then the radio just reports "BACKUP ERROR" on the display and does nothing else at all. In the case of my radio, it trashed the contents of the Model 9 memory station in such a way that anytime I try to access the Model 9 slot the radio hangs.

The DX7 is a pile of horse poop as far as memory protection goes. First off, they couldn't figure out a more reliable scheme for backing up the long term memory? Second, the radio can't figure out how to validate its own internal storage before trying to use the data contained therein? (Think CRC.) Third, the user data space and operating program space are not kept separate and protected from each other? Last, the stupid-ass radio can't detect that the FLASH contents have gotten scrambled and re-initialize itself back to factory default?

What? Huh? What? This is the only FLASH-based embedded device I have run into in the last thirty years that had this level of stupidity designed into its behavior. Had I been responsible for this mess I'd expect to be kicked off the client's property covered in tar and set on fire. If I had worked next to the engineer(s) responsible I'd have killed and eaten him(them).

Here's to hoping that the DX8 cures a lot of these problems. It couldn't possibly be any worse.
Posted by A Useless Geek | Dec 05, 2010 @ 06:23 PM | 6,672 Views
The stench from the Ironing Board fiasco still fresh in my nostrils, I made another prop-in-slot mid pusher park jet real quick to clear my palette. Another basic delta. In fact, an actual delta! Nothing wrong with an isosceles triangle that proper C/G placement can't cure.

Balsa leading edge rounds used as longitudinal stiffeners. [By the way, the balsa used for leading edge rounds seems to be denser and stiffer than the wood used for wings and such. Works out well.] One piece of carbon fiber round tube (rescued from another plane) used as a lateral stiffener.

Flew fine out at the golf dome last night. Two batteries and no objectionable behavior.

Length: 774 mm
Span: 484 mm
Height: 167
AUW: 260 grams (186 dry plus 74 battery)
Battery: Turnigy 800 mAH 3S 20C
Motor: Welgard 2208-08 2600 KV (400 class)
Prop: APC 5x4
ESC: SS 20A, with mods
Servos: hexTronik HXT500 (2)
Rx: AR6100e
Posted by A Useless Geek | Dec 01, 2010 @ 01:17 PM | 6,672 Views
So, I was running low on planes to fly out at the golf dome. (I sold some off, crashed a few, and loaned out a bunch.) This was just an idea from some leftover foam that had a certain shape to it. I used a balsa leading edge strip running down the middle of the underside to stiffen the backbone. There's a GWS plastic stick mount to hold the motor in place. Not much to this thing.

After the fact I thought up ways to improve it, of course, such as an iron-shaped vert stab, a cross-braced undercarriage (to look like the folding legs) and some other stuff. Still, not bad for the little work I put into it.

The Ironing Board will get its debut out at White Pines tomorrow night at the SRCB club indoor. We'll see. Hey, look -- I needed another plane, okay?

AUW: 209 grams
Length: 815 mm
Span: 217 mm
Servos: (3) HXT500
ESC: Hobby King 15/18A
Motor: E-Max CF2805 2840 KV
Battery: Turnigy 2S 800 mAh 20C
Rx: Spektrum AR6100e

Later:

Um...not so great. Flies Like Chicken. (Tastes like it, too.) Gonna hafta add polyhedral extensions to the sides to get it stabilized. Maybe I ain't as smart as I thought I were...?

Later still:

Did a bunch more to try salvaging this beater. Flew like total kaka. Uhn-uh. Scrap.