OK, so I did the first fitting of the electrical stuff in the nose of my new plane. How short should cables be. I can get it all in there, but I feel like the wiring is going to obstruct the air flow pretty badly. I've got some space to shorten the wires quite a lot. Can I do that without problems?

Here's a look. Suggestions welcome.

Shorten them up.  If you don't the problems will be cooling problems.

Chris,

There are vents over the motor that lets in air right on top of it, down the top block and out vents in the top right over the battery.

yes, the battery slides out behind the ESC. You have to take out a screw to take the little hold down lever off the battery, then that can back out and the battery slides right out behind the ESC. I checked that out pretty thoroughly. It's interesting trying to figure all this out and still get air through everything.

The nose is Swiss cheese. Trying to get enough air in and out, keep structural integrity and find room for everything is a new challenge. And fun, too.

I don't know that you need huge amounts of airflow.  When cooling electronic circuits it's pretty obvious that the first little breath of air does a huge amount -- it's all diminishing returns after that.

Consider that a lot of electronic circuits are cooled by heat-sinks that have fins running up and down, with the only air motion supplied by natural convection.  That's less air movement that you get waving your hand at the thing, yet it makes a significant difference.

Having someone do testing would be nice.

I don't know that you need huge amounts of airflow.  When cooling electronic circuits it's pretty obvious that the first little breath of air does a huge amount -- it's all diminishing returns after that.

Consider that a lot of electronic circuits are cooled by heat-sinks that have fins running up and down, with the only air motion supplied by natural convection.  That's less air movement that you get waving your hand at the thing, yet it makes a significant difference.

Having someone do testing would be nice.

so Tim, when are you starting your testing then?

Electronics generally start misbehaving at considerably lower than melted solder temperatures.  I don't know what Castle is designing to, but +85 degrees C at the board surface is a common temperature for automotive and military-specification parts, and you can get there pretty easily if you're dissipating considerable power.

Unfortunately for those of us who are tightwads, electronics have to be designed for the operating temperature they'll be subjected to.  This means that el-cheapo ESCs may not be as happy as good ones at really hot or really cold temperatures.  It's a crap shoot, unless the ESC was specifically designed for and tested at the temperature extremes.

The rule of thumb for electronics is that if you can hold your thumb on it without saying "ouch!" then it's not too hot (this is for electronics at room temperature, when you're designing them to operate at +55 degrees C -- the electronics can actually be hot enough to hurt when you hold them, but only if they're carefully designed.  It gives you lots of margin with an ESC).

Motors can go considerably warmer, but will eventually suffer from bearing issues.

Battery packs should feel no more than discernibly warm.  If they're close to "ouch" temperature then they're probably too hot.  If they're puffing up and smoking, or if the nose of your plane catches on fire, they're probably too hot.

well as to batteries,, they PREFER to be used at somewhere around 100 degrees when you start, so cooling the battery will actually be detrimental to performance, signigicantly,, I fly RC and I KNOW that when it gets cooler,, 50 degrees or so, my battery life is significantly shorter in flight,,

as to temp for the motor, I think that I have seen 160 degrees as the top safe temp, the limiting factor seems to be the adhesive that holds the magnets to the can...
as to the ESC, electronics from my experience perform better when they are cooler, when they get warm, they tend to fall away from tolerance,,

 It's a part of the reason that military equipment costs so freaking much.

$400.00 Snap-on Hammer? LOL the biggest part of the cost is greed. They see the military as deep pockets.

Those of you who have even a slight mechanic’s mind will love this.
You don’t have to be an engineer to appreciate this story...



A toothpaste factory had a problem. They sometimes shipped empty boxes without the tube of toothpaste inside. This challenged their perceived quality with the buyers and distributors. Understanding how important the relationship with them was, the CEO of the company assembled all of his top people. They decided to hire an external engineering company to solve their empty boxes problem. The project followed the usual process: budget and project sponsor allocated, RFP, and third-parties selected.
Six months (and $8 million) later they had a fantastic solution - on time, on budget, and high quality. Everyone in the project was pleased.

They solved the problem by using a high-tech precision scale that would sound a bell and flash lights whenever a toothpaste box weighed less than it should. The line would stop, someone would walk over, remove the defective box, and then press another button to re-start the line. As a result of the new package monitoring process, no empty boxes were being shipped out of the factory.

With no more customer complaints, the CEO felt the $8 million was well spent. At the end of the first month, he reviewed the line statistics report and discovered the number of empty boxes picked up by the scale in the first week was consistent with projections, however, the next three weeks were zero! The estimated rate should have been at least a dozen boxes a day. He had the engineers check the equipment and they verified the report as accurate.

Puzzled, the CEO traveled down to the factory, viewed the part of the line where the precision scale was installed, and observed that just ahead of the new $8 million dollar solution sat a $20 desk fan blowing the empty boxes off the belt and into a bin. He asked the line supervisor what that was about.

"Oh, that," the supervisor replied,"Bert, the kid from maintenance, put it there because he was tired of walking over, removing the box and re-starting the line every time the bloody bell rang.”

Never believe a story that doesn't come with names and dates, or at least sufficient detail: http://www.govexec.com/federal-news/1998/12/the-myth-of-the-600-hammer/5271/

I bet I can buy it cheaper. It doesn't matter what they are paying they are always over paying. By a lot. The next thing is the waste!

When I was in the Navy they were sending Snap-on tools out by the truck loads to be scrapped. Why not just have the Snap-on man come and replace them? Please don't tell me this is not true. I know this for a fact. Also there was nothing wrong with them at the time. The only thing was the date code or some nonesense along that line.

sorry to continue the thread drift, but,,,

from my time in the airforce,, and working in supply while waiting on my crypto license,, what I saw was ridiculous specs,, some general would say " we need phillips screwdrivers,, #1 and #2,,," procurment would ask,, how long do you want them to last,, what should they be made of,, etc etc,,,, so the general would say, well it needs to be this and this,, so procurment would order that,, low and behold, there were no screwdrivers matching the "spec" that they came up with,, hence they would be required to custom fabricate a relativly small number of over-engineered screw drivers,, not better, just different because someone out of ignorance spec'd some obscure number,,,

Tim, this was 77-81

I was referring to your interest in getting things cheap and your aversion to engineers.

Sparky is my kind of guy.  Learn by doing.  Not by reading.  I remember a couple of telephone schools in which I wondered where the instructors got their education.   Nothing like trying to get circuits to work that some telephone engineer drew up.  Lost count how many times we would get a circuit working to the customers satisfaction and then the engineer tell us it can't work that way.  I guess that is why I don't design model planes.