iron eagel

His truck will, when it's done.

rcguy59

My Feedback: (8)

Went out to the field today and got a surprise. The place was PACKED! I've never seen it that busy before. The weekend guys were there due to the holiday and the usual Monday crowd was there, too. Never had I seen that many electric foamies in one place, either. Wanna see how fast three guys can land foamies? Launch a Demon into their midst. They were all a little jumpy after that. They were really good sports about it and I restrained myself to three flights all day, It was great fun to see how many new and spectacular ways there are to separate the little beads that make up foam. I also learned that every electric airplane can have a smoke system... Once. I even saw open flames emanating from the cockpit of a DH Vampire after a smoky emergency landing. There was even a foam Demon, of sorts. I HAD to have a picture of that. One of my buddies bought Demon #1 from me today. He bought just the airframe, as he has everything else already. If someone installed some R/C gear in a toaster oven, this guy could take it up and make it look good. He was my mentor when I got into turbines, and he keeps the grounds of our field in top shape, too. Thanks, Karl. My buddy Steve got a couple of minutes of video of my last Demon flight, launch-to-landing. As soon as it's up on Youtube, I'll post a link.

rcguy59

My Feedback: (8)

Here you go. http://www.youtube.com/watch?v=pa0jmNXeMU8

iron eagel

Looks like you were having a blast.

rcguy59

My Feedback: (8)

I was. I cut the flight short for the sake of Steve, the cameraman. My normal flight time is 5-6 min.

MJD

My Feedback: (1)

Fantastic! I'd say you're comfy with the aircraft now.

The acceleration from hand launch is surprising – light weight will do that for you.

There’s one problem with almost every Demon, happens all the time. About 15-20 seconds after the first launch, the throttle becomes ineffective, and seems to work more like a switch.You can set it low after fueling to start, then when you launch at full throttle – it just stays there the whole flight as the pilot yells "woo hoo!" and flies around like a madman for 3-4 minutes.

combatpigg

My Feedback: (3)

It really looks great..!
You weren't kidding about the supply and demand situation at your field. A plane like the Demon sells itself when folks see it in person.
Your cameraman does a nice job of tracking those laps. I'll bet he's pretty good with a shotgun too.

rcguy59

My Feedback: (8)

Don't know how he is with a shotgun, but he sure likes M-1911's. One of the many things he and I have in common. Yes Mike, mine seems to have the same defective throttle as the rest. "Start" and "Launch" are the only two settings that seem to work. They work REALLY well, though. Here we go again... Tonight I started framing up the parts I cut on the bandsaw. Note that the fwd. spar has moved aft by 1.25". That was to make room for the battery. I got a request on Sunday for a Demon set up for e-power, and I accepted the challenge. This one will be for me and the second one with any needed refinements will be for my buddy. I got a 1500W, 1600KV heli outrunner for a 6S pack. When I gutted Demon #1 to get it ready for Karl, who bought it, I laid out the e-power system on top to check placement vs. CG. Moving the spar 1.25" seemed about right. I'll know for sure in a few days. Weight should be right around 3 lbs. Please note, Mike, there are no pieces of 1/4" dowel in the spars. They go right into the ribs. Seems to work fine.

MJD

My Feedback: (1)

Yup.. I've already started drawing in those changes.

Rudeboy

I've got a 1600kV outrunner for a 500 size T-rex heli in a MPX Dogfighter. I run it on 5 cells and an APC 7x10 prop. It draws well over 100 amps.
Don't know what motor you have there, but you'd need a really tiny prop to run a 1600kV motor on 6S.

If I were to put the motor I have in a delta this size, I'd be looking at an 8" prop and 4S. Probably an 8x7 or 8x8.

rcguy59

My Feedback: (8)

Thanks Rudeboy. That's exactly the kind of advice I need. I was thinking 6.5-7" dia. and about 5-6" pitch on 6S. I was going to try 4S first, so thanks for reinforcing that idea. I happen to have plenty of 8-7's and 8-8's for my .32's. My motor is a Chinese cheapy, so I doubt it will survive 100+ amps for long. I was planning to try to hold it under 90 amps peak, as it's rated at 75. They're only about $20.00 ea., so a smoked motor here and there isn't a disaster. I've got a 150 amp ESC I was planning to use. What brand of motor are you using?

iron eagel

Four cell and the 8/7 should be a good match, the 6.5X7 on a six cell should haul. What type of constant wattage is it rated at? You should be able to push 150% of the rated wattage for a couple of minutes anyhow with good cooling. I have done it with the cheap Out runner motors and they have held up without cooking a bearing or magnet, but they probably only have 3 or four hours each of total flight time. Stick with a real fast ESC when using a 6 pole motor (a good ESC with program limits will be able to survive frying the motor).
Edit to add:
Is your ESC a data logger that will really help you out.

rcguy59

My Feedback: (8)

Constant wattage is 1500. This motor is 8 pole. The ESC doesn't have data logging, but I do have the programming card for it and I installed the external voltage harness to send battery voltage data back to the transmitter so that I can set up a low-voltage alarm via the telemetry.

iron eagel

As long as you have good cooling I can't see why it shouldn't work for awhile.

mmattockx

That should be the motto for this forum...


Mark

Rudeboy

This is the one I'm using, also a chinese cheapo.

http://www.hobbyking.com/hobbyking/s...ter_Motor.html

It handles the amps just fine. Just don't keep the throttle pegged, and don't use a spinner. Or use a small spinner, but make sure that the motor windings get hit with the full speed airflow. Proper cooling keeps these things alive at 150%+ of rated power.
The same goes for the ESC. I shorten the motor and ESC wires, and solder the together, no connectors. Shortening the motor wires is a pain though, because you have to remove the lacquer from the strands

iron eagel

Excellent advice!
Keeping the leads short is very important to minimize loss.
Another thing to consider is keeping the battery side of the esc leads as short as possible to reduce the ripple and strain on the Caps on the ESC. The shortened leads from the batter to the ESC reduces loss because of wire resistance and keeps the copper cooler which keeps the impedance lower as well. This is a major consideration with an electric motor because it is very low impedance load and any reduction in resistance anywhere prior to it make a big difference in the performance of the motor.

iron eagel

Rudeboy

Charging and flying your lipo's hot also makes a remarkable difference in power delivery.

There's a reason the F5D guys are always messing with lipo heaters

combatpigg

My Feedback: (3)

I am Combatpigg and I approve of this message..............

iron eagel

Originally Posted by Rudeboy

make sure that the motor windings get hit with the full speed airflow. Proper cooling keeps these things alive at 150%+ of rated power.


Rc,
If the front of the motor isn't the front of the plane you need to have a cowl something like this (see below) to make sure the interior of the motor has airflow over the windings. You also need to vent the holes on the back of the motor into an area of low pressure to make sure it moving out well.


It is centered but I was a bit off with the camera position...

rcguy59

My Feedback: (8)

Been working on it again tonight. Once I test-fitted the motor, I decided to do some watt-meter pulls with some different props. Started with 4S and an APC 8-6E. 104 amps. A bit much. I must have sorted through 50 or 60 props and couldn't find anything I wanted. So I cut an APC 8-7 sport prop down to 7" diameter. I got 79.4 amps out of that one, 1131 watts. That will be my starting point until I can find some more suitable props. The LHS didn't have any, either. Figures. I ditched the spinner, as it was preventing good cooling airflow. I'll finish the airplane before I do any more test runs. Here's the progress.

iron eagel

Cool.

OliverJacob

My Feedback: (12)

I wonder why we don't see more of these planes. Simple design, lot of speed and fun.

Right now I am building a BTE Vortex and will put an OS 91 FX with a Macs pipe on it. This won't be crazy fast, but good enough to get my feet wet and
then move on to faster deltas. Does anybody have recommendation on the prop size for this?

Years ago I build a SD and wasn't quite ready for it, so the Vortex is my delta trainer.

And I have that pulse jet engine sitting on the shelf...

iron eagel

You will have to talk to MJD about that.