twinturbostang

Yeah, I know how the prop sizing goes. Small and high rpm for speed and aerobatics. Large and low rpm for 3D. But I definitely don't plan on doing 3D stuff for a while. I've got a LONG ways to go before I can do maneuvers like that. And right now, sport flyers and aerobatics interest me more than 3D does anyways. I mean, if I really want to hover, I can just pull out my heli. So I think I'll be ok.

Matt Kirsch

My Feedback: (21)

Wow, quite a thread

That LiPoly and brushless motor will turn it into a real barn-burner, that's for sure.

Hindsight being 20/20 and all, what you're seeing with the battery life and overall performance is pretty much exactly what I'd expect from that setup. Battery's not quite robust enough to run a 400 motor... You'd probably see better performance with the EPS300C and that battery. It's lighter and spins a larger prop at a lower RPM. With my E-starter, I was regularly getting 12 minute flights on 700mAh AAA NiMH cells because the Amp draw was much lower.

If you ever get the opportunity to fly in a full-scale Cessna or other small aircraft, you'll learn all about coordinated turns, using rudder and ailerons together to "keep the ball in the center." Coordinated turns are mandatory in full-scale aircraft; bank-n-yank is VERY uncomfortable for the occupants of the plane. Most models exhibit that "tail dragging" behaviour to some degree too, though scale models like the Piper Cub, and E-Starter (a semi-scale Cessna 152) exhibit it more than others. Don't worry about it; it's normal, and learning to make all your turns coordinated is a GOOD thing. Looks pretty in the air, too

twinturbostang

lol I hope it doesn't rip the wings off of it!

You're saying the 300C would actually outperform the 400 as well? Interesting. The AAA cells are obviously just not big enough to give the amps that the 400 motor requires. I've gotten a little better at throttle management now. Not running it WOT the whole time. And that seems to help. Battery is still pretty warm/hot after a flight. But not "scalding" hot as before.

I have been in full scale Cessna's before, although not in a long time. I actually got to do a take off once. Very interesting feeling. You MUST correct for torque upon full throttle by giving it a bunch of rudder (steering input). Otherwise you will run off the side of the runway! No that didn't happen. But it would have if I had not corrected for it. Back to the models... I'm learning how to do coordinated turns. I've found that high bank turns require more rudder input. But sometimes I'm not sure what to do. If I do a moderately high bank turn, the tail will drop some. For instance in a right turn, the tail drops, so I give it right rudder to bring the tail back up. But in the mean time, the plane is slipping down, loosing altitude due to the decrease in lift. That would mean I need to give left rudder to hold altitude. But that will just worsen the planes attitude/orientation in the turn. Hmm. Maybe I need to work more on coordinating bank angle with turn rate. ie: maybe more elevator input is required at that particular bank angle. I may be inadvertently doing a partial knife edge (high bank angle and low turn rate). I noticed that when I do nice gradual low bank turns, it looks a whole lot better. Much more graceful.

Flypaper 2

Stang:
If it's slipping in the turn, either back off on the bank angle or more up elevator. Good thing we're not sitting in it or we'd need a couple of barf bags

twinturbostang

Haha. Oh, the inside of the canopy would be quite a mess by now!

TManiaci

My Feedback: (6)

Yea, and adding a little power into the turn helps hold altitude as the drag increases from all the controls digging into the wind and the lift is lost from the banking attitude.

twinturbostang

Yeah, that would work. Except that a lot of the time I'm still at full throttle.

Matt Kirsch

My Feedback: (21)

Simple rule of thumb is, the higher the bank, the tighter the turn. If it's falling out of the sky, you banked too much for the size of the turn you're making. Either roll out to a less steep bank, or tighten the turn by giving more up elevator.

twinturbostang

Hmm, well this is a bummer. I was hoping to post tomorrow that the plane is up and flying with a new power combo. But, there was an "incident". First the combo...

- Dymond Tornado 400F outrunner and 25A esc combo
- Dymond 2100 3S 12C Lipo

I built a motor mount for the motor using spruce sticks and ply construction. See picture below. Got it all set up and bench tested the motor to make sure it was turning in the right direction. Had to swap two wires and then I did some power testing. This is where things go bad real quick. Had it at 1/2 throttle and advanced to full. The motor had SO MUCH torque that it ripped the motor mount apart!! Seemed like stuff was flying all over the place (pieces of the mount). I yanked the throttle back to min and the motor stopped. It had wound all the wires into a nice weave. But it appears there was no damage, aside from the wrecked motor mount that is. It's a GOOD THING I was being very careful during the first test. I had the motor/prop turned away from me and at arms length. That could have been real bad otherwise.

Anyway, I'm at a loss right now. I had no idea that itty bitty motor would have so much torque! After looking at the pictures of the mount, I see I severely compromised the strength of the mount by trimming the top supports. That was necessary because I don't have much room inside the cowl. So, do you guy have any ideas for building a stronger mount?

TManiaci

My Feedback: (6)

twinturbo-twisting-stang,

Excuse me while I pick myself up off the floor [sm=tongue.gif].

Sorry, I had to find humor in that one... LOL.

Well, it is obvious to me that the weakness is the four struts did not penetrate the fuse. To take the torque, you need to anchor the bars at least 1/2 inch into the fuse. I used Gorilla Glue on the [link=http://www.rcuniverse.com/forum/fb.asp?m=2995952]EXTRA MOTOR MOUNT[/link] to fill the hole well. It grows and spews out as it expands, then sets really well.

Just make the bars longer, drill some holes in the foam and push the bars in with epoxy or gorilla glue. Make a couple gussets on the mount to strengthen there. That will make it tough.

TManiaci

My Feedback: (6)

BTW: You should put some 1/4" holes in that motor mount to get airflow into the inlets in the front of the motor. You don't want it to overheat...

twinturbostang

I guess I can laugh at it now. But it sure wasn't funny when it was happening! Good thing I was as cautious about it as possible, othewise it might have been a trip to the ER.

But, I think you're right. I need to build a mount more like what you have. What I really need is an aluminum front mount like what yours. Then I could use dowels and reduce the width of the front mount, hopefully fitting inside the smallish cowl. And of course extending the dowels through the rear plate and into the fuse. Question: is the bolt pattern on these motors standardized? I need to know if I can go to the lhs and get a mount that would fit my motor. It looks like the four screw holes are at two different mount widths. Didn't know if this was normal or not.

BTW, I'm not really impressed with the Dymond 25A esc. It seems rather big and heavy (relatively speaking) and there is only one thing you can program, which is the brake. And actually, this may have been part of my problem. I left the "brake" at the stock setting of off, thinking that it was exactly what it sounded like... a brake for when you close the throttle. BUT, it also enables a soft start (they all this a brake?!?!). I noticed that the motor was hard to start sometimes. If I didn't advance the throttle really slowly it wouldn't start the motor. It would just jitter and make noise. It could be that if I had selected the brake, there would have been less stress on the motor mount. But oh well, I'll build it better and stronger.

TManiaci

My Feedback: (6)

torque-twisting-'stang,

Yes, that plate is a standard outrunner adpater plate. The pattern is from the AXI 22XX line of motors, which has more-or-less become common. If you get a backplate for a AXI 22XX, it will bolt right up.

That Dymond Sky Advantage ESC is actually rated for 35 amps for 10 seconds, so it is strong. Yea, it weighs 22 grams, a little heavier than Pheonix 25 at 17 grams ($65), but a Jeti 30 amp is 28 grams ($45). So it's in the ballbark. No, it is not galmorus with features, but consider you bought a motor and got and ESC for free. Comparable name-brand motors sell for over $70 alone.

At 2250 Kv on 11.1V, that motor is going to need a small prop, so take care not to overload. My guess is APC 8x3.8 to 8x4.7 SF or an 8x5E is the right starting point. And YES, they are "torqu-ie"... you got alotta power there in a small package.

twinturbostang

Cool. I'm going to get one of those and then use dowels to connect to the back motor plate. Hopefully there will be enough clearance in there for the cowl. Are there different sizes of the X plates though, in how far out the mounting holes for the connecting struts are attached? The motor on your Extra looks to be larger in diameter than my 400F.

True. You get what you pay for. I really don't need a whole lot of features at this point. But the one thing that concerned me was not having the ability to set the LVC manually. The instructions say it is hard set at 65% of whatever the starting voltage is. So I must make sure that each time I plug it in, the lipo is fully charged. Otherwise I could possibly run into a condition where the voltage is low to begin with (say 1/2 charge), which would further lower the LVC, and possibly into the danger area.

I got a 7x4 APC prop. It's not a slow fly prop though. Much more rigid looking. I'll have to take a picture of it. But since this motor spins very high, maybe it's best that I have something a little more sturdy on there.

twinturbostang

Oh btw, what size diam. dowels are you using, and what size hex head bolts?

Thanks,
Brian

TManiaci

My Feedback: (6)

'stang,

The style prop you are referring to are called "sport" props, and usually are differenciated by the "E". They are better for high-revving applications for speed. You have the right one to start off. Do you have a wattmeter? Would be nice to know how your current draw is... if not, just feel everything immediatly after flight to make sure it's not really hot. If you can't hold your fingers on it, it's too hot and overloaded.

Those were 1/4" hardwood dowels, with socket-head servo screws for attaching. Don't know about other X patterns and I don't have the dmensions handy with me to see if the Tornado is the same diameter as the Maxi line. If you look close, you will see that I had to relieve the inside of the dowels to clear the motor body on the Maxi.

twinturbostang

Cool. Sounds like they set me up with the right prop then. No, unfortunately I don't have a watt meter. I have a volt/ohm meter that also reads amps, but definitely will not read in the range that these motors draw. I think it's 5A fused or somewhere around there. I guess I would need something that could handle at least 30A current draw. Is there any way to back out the amp draw via prop size, thrust, rpm, or anything like that? I currently don't have a way of measuring rpm either. But I may be able to figure out some way of measuring thrust via my digital kitchen scale, which reads oz or grams.

I was looking at your motor mount picture and then comparing it to mine. Looking at the motor mount screws and basing the diameter of the motor off of that, it looks like they may be similar in diameter, with the Maxi possibly slightly larger. Hard to tell. I'll just have to measure the diam. of mine. I called the lhs and they are currently out of the "X" plates. [] Was hoping to get back in the air this weekend, but that might not happen now. They said they were expecting a shipment in tonight. Hopefully some of these plates are on the truck and will be available tomorrow morning. Damn, I must be addicted to model flying again, cause I'm starting to have withdrawl symptoms from not flying since earlier this week! haha What the hell do you guys do during the winter months?!?!?

TManiaci

My Feedback: (6)

play with this Wattage Calculator [link=http://www.coloradogliders.com/propellerloads.htm]HERE[/link]. But, it leavesthe rpm as an unknown, so you can only play with it to feel it out. You need amps/ watts or rpm to get the number... too many unknowns.

In Southern California, we fly all year round [8D]

twinturbostang

Back in bidness! It's all ready to fly again now. Nobody had an aluminum mount in stock... so I made my own! It's not as pretty as a CNC cut mount, but hey, it works. I've run it up on the bench a bunch of times and it's holding solid this time around. It's interesting though. I thought the plane would be lighter. But it's actually 6 grams heavier now! Well, the motor is lighter and I did remove 1/4 ounce of tail weight. But the battery I've got in there now (2100 3S lipo) is a little heavier. And the new brushless ESC is definitely heavier. Plus I had to make a new battery door. I had to do a lot of trimming and stuff to get the thicker 3S lipo in the battery compartment. So that required a new battery door also. But anyways, it's basically the same weight as before (what's 6 grams !?!?). It's a whole lot more powerful now though. I think it's got some vertical potential now. Bench testing it, it wanted to pull vertical out of my hands! And I think it will last a long time on the 2100 battery.

Oh... battery's done! Time to go flying.

twinturbostang

So much for that. I killed it. Got 5 minutes of flight time. Wow that thing was fast!! Felt like twice as fast with the new combo. But then disaster struck. Was pulling a high bank turn, and all of a sudden, I noticed something "left" the airplane. I lost complete control after that and it did a nose dive from 200 ft into the ground. Can you guess what "left" the plane?? Yep, the battery ejected from the plane. And of course when that happens, you loose total control. All I could do was watch it go straight into the ground. []

Damage is pretty severe. I don't know if it's fixable. Actually, I don't really want to fix it at this point. Believe it or not, the new motor mount I built survived! That was the first thing to hit too! Prop was ok. Motor looks ok, except I think the shaft bent just slightly. It's so slight that you can't even tell it's bent unless you have the motor fixtured and you spin it. I hope I can bend it back. I'm going to put a dial indicator on it and measure run-out as I spin it. Battery however, is toast.... LITERALLY! It fizzed, popped, and smoked a whole lot! So much for my brand new 2100 3S lipo. At one point, I considered running for a fire extinguisher, because I thought the grass was going to catch on fire. It was a pretty spectacular display!

So it looks like I've lived up to the thread title I started. [] BTW, what's the proper method of disposal of these lipo's?

TManiaci

My Feedback: (6)

'stang-bang,

Damn, sorry you lost it. I was reading the first post, was going to commend you on that "great battery door", guess the second post changed my mind. I assume the latch device failed?

At least the motor mount survived, not to funny to you I suppose. It's always a sinking feeling when parts part with the plane... boy, that batery must have hit something hard! I smashed one real bad once, flatened it out and have been flying it for two months without ill effects.

Where's the video camera when you need one, huh?

Well, one of the guys I fly with ALWAYS says, "Never get attached to your planes, they will all crash one day"... I hate it when he says that. Alas, it's true.

Again, kudos on the setup, sorry for the loss.

TManiaci

My Feedback: (6)

Hey 'stang... do I see an instruction manual for the Ultrafly Extra 300S there in the crash photo? Now that one is an advanced flyer...

twinturbostang

Haha. Yeah, I'm assuming so. Still not exactly sure how it opened though. The door was still attached to the plane, but of course in the open position. I pulled on it several times before the flight, with considerable force, and it did not open. So I don't get it. [sm=confused.gif]
Actually, the aluminum piece I made bent slightly. It can easily be bent flat again though. I'm more concerned about the motor. But I'm hoping the shaft can be bent straight also, since it only moved a tiny bit.
Hmm. I don't know. It hit the ground, which was a grass field. It was one of those Dymond packs though. I don't know if that made a difference or not. Eg: would I still have a lipo pack if it had been a TP??
Yes, you're right. If you're own flying doesn't get you, an equipment failure will! lol

Still trying to decide what to do at this point. Yes, that is an Ultra Extra 300S I'm building. I guess you didn't see my build thread here: http://www.rcuniverse.com/forum/m_3346729/tm.htm So the dilemma right now is should I scratch the E-Starter and finish building the Extra? Or try and glue the Humpty Dumpty E-Starter back together and hold off on the Extra? BTW, where do you get the Gorilla glue at?

twinturbostang

I put a dial indicator on the motor shaft and it was out .008" at the tip. But at the end of the prop adapter, it was wobling .025". Definitely bad. I ran it up to 1/2 throttle on the bench and it was staring to make some BAD sounds, so I shut it down. Tried to bend the shaft back, but uh... it broke. Looks like hardened steel. It doesn't like to bend too much without breaking. So looks like I've got to get my motor fixed. Dymond said I can send it in to them and they can press a new shaft into the can. That means no flying for at least a week though. We need a "pouting" smiley.

TManiaci

My Feedback: (6)

Bummer on the motor. That sucks.

Oh, I found the Gorilla Glue at Office Depot, believe it or not. I think Lowes has it too.