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Old Jan 10, 2009, 11:09 AM
Slow Flyer
Bombay's Avatar
Richmond, TX
Joined Apr 2008
3,236 Posts
Quote:
The wiring where it goes into the motor? How do I fasten that so that it does not flex? Any tips are appreciated.
RBrown:

On most of these low $ motors, the wires going into the motor are extremely thin and unsecured. I noticed this while upgrading my Slo-V to brushless. I asked a similar question on how to secure these wires and got good suggestions here.

I ended up using Permatex Hi-Temp RTV Silicone Gasket Sealant (black)...basically high-temp silicone. I got it at AutoZone. I used it sparingly (applied with a toothpick) and so far the results are good. Hope the suggestions (and warnings) in the thread help.

Rob
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Old Jan 10, 2009, 01:32 PM
if it dont fly i dont want it
north east uk
Joined Jul 2006
62 Posts
Quote:
Originally Posted by FLYPARTY
mdennis,
Great painting job!!

rbrown3rd,
The EPP eagle is also suitable for slow flying with little power. Looks like you have got a hang of it!! What I love the most of flying eagle is to see it circling slowly in the sky like a real eagle.

Flyparty
yes flyparty. thats the way i like to fly my eagle too i have a
tower pro bm2408-21 bell motor 140w
a 20A esc and a 7.4 2s and 11.1 3s lipos. the bird flyes great on the 7.4 is wicked on the 11.1 i have over 100 flights on my eagle with no problems at all.
well sorry one problem when i turn up at the field it is empty as soon as i start flying my eagle every bird for miles around comes over to have a look its real funny watching them mob the eagle
i have flown the eagle in winds up to 25mph and it will fly backwards and land like a helicopter from 30ft if the wind is right
this is a great kit and if you are thinking of buying one then go for it
regards
mick
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Old Jan 10, 2009, 01:36 PM
Addicted to flight since 1944
rbrown3rd's Avatar
southern Florida
Joined Feb 2004
1,750 Posts
Quote:
Originally Posted by FLYPARTY
rbrown3rd,

Brushless motor will not catch fire because of water.
From your photo, my guess is that your motor is under-power for a propeller that is a bit too big which caused the smoking/fire.What is the specification of your motor, propeller, ESC, and battery?
All of the explanations posted make sense. But, the ESC was, WAS, a 20 amp ESC. I am suspecting a direct short around the wires leading into the motor. I am going to examine the motor more closely later today.

I don't think the motor is underpowered but I could be wrong. The specs follow: (not my tests but Dan at Lazertoyz. The prop was an 8x4. If anything it was underpropped a tiny bit.

Motor specs and info.

2 cell
9X4.7
12 oz thrust
6A (45 watts)

2 cell
8X4.3
11 oz thrust
38 watts)

3 cell
9X4.7
20 oz thrust
10A (115 watts)

3 cell
8X4.3
19 oz thrust
7.5A (85 watts)
.......
As always I admit to very little knowledge or experience with electric power so what all of you say is probably true and I am wrong. It won't be the first time. I am learning though thanks to responses from you all.

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Old Jan 10, 2009, 02:08 PM
Addicted to flight since 1944
rbrown3rd's Avatar
southern Florida
Joined Feb 2004
1,750 Posts
Quote:
Originally Posted by Bombay
RBrown:

On most of these low $ motors, the wires going into the motor are extremely thin and unsecured. I noticed this while upgrading my Slo-V to brushless. I asked a similar question on how to secure these wires and got good suggestions here.

I ended up using Permatex Hi-Temp RTV Silicone Gasket Sealant (black)...basically high-temp silicone. I got it at AutoZone. I used it sparingly (applied with a toothpick) and so far the results are good. Hope the suggestions (and warnings) in the thread help.

Rob
I can say that I did not do any sort of preparation or setup as described in the thread. I have a Park Shark that I have many hours on with the same motor but back when I built that one I was advised by a friend to wrap the leads coming into the motor with thread and to CA the wrapping. At least I think that is what he told me. I may have it in my notes somewhere. Anyway, my point is that both planes used the same cheap motor and the Park Shark is still flying with lead protection and the Eagle is waiting for a motor with no lead protection having been done on it.

Update. My friend advised me to tie off the leads with thread for strain relief. He has vast experience in electric power and prefers the stick mounts to the firewall mounts.. He also did some thrust testing:

2-cell--T---A
7060 6.0-4.3
8040 7.5-4.0
8060 7.7-5.0
9050 9.6-5.4

3-cell--T---A
7060 11.5-7.0
8040 13.0-6.0
8060 14.0-8.8
9050 16.0-9.0

Here is a photo of his strain relief for the motor leads.
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Old Jan 10, 2009, 03:36 PM
Slow Flyer
Bombay's Avatar
Richmond, TX
Joined Apr 2008
3,236 Posts
Good. Well, I guess the important thing is to secure the leads on these motors...regardless of the mechanism used.
Rob
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Old Jan 12, 2009, 09:07 AM
Registered User
FLYPARTY's Avatar
TAIWAN
Joined Dec 2003
139 Posts
Mick,

Thanks foryour praise and sharing. I am looking forward to seeing some of your eagle flying photos or videos!!

rbrown3rd,

With the following recommended parts, the EPP Eagle should have very good flyping performance and better mobility.
2208~2212 /900~1100kv
prop 9050
2~3cell
500~700 thrust
max 14A
20A ESC

I am also learning new information liike everyone else. If there are questions or suggestions, please feel free to post it for discussion!!

Flyparty
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Old Jan 12, 2009, 03:19 PM
NaN
Andy2No's Avatar
Manchester, UK
Joined Nov 2005
3,756 Posts
Quote:
Originally Posted by rbrown3rd
I don't think the motor is underpowered but I could be wrong. The specs follow: (not my tests but Dan at Lazertoyz. The prop was an 8x4. If anything it was underpropped a tiny bit.

Motor specs and info.

2 cell
9X4.7
12 oz thrust
6A (45 watts)

2 cell
8X4.3
11 oz thrust
38 watts)

3 cell
9X4.7
20 oz thrust
10A (115 watts)

3 cell
8X4.3
19 oz thrust
7.5A (85 watts)
I may have missed it, but this begs the question, what number of cells and prop were you using?

The BlueWonder is capable of all that, but not for very long at all, due to the low weight. Lightweight motors can only take brief bursts of power before they overheat. I've read other cases of Blue Wonders burning out, flying fairly light planes.

They're really most suitable as a shock flyer motor, where the current is below 3A a lot of the time, and goes over 6A only in very brief bursts - like a quick aerobatic flourish before the tiny lipo those things use gets drained.

The heat created by a motor is I*I*Rm where I is the current and Rm is the armature impedance aka internal resistance of the motor. For a Blue Wonder, the Rm is on the high side. The capacity for a motor to dissipate heat is limited by the weight of metal in the motor. For a BW, that's on the low side.

A short of the wires leaving the motor could well destroy your ESC, but would leave the motor relatively undamaged - apart from possilble scarring at the site of the short.

Shorter version: As FLYPARTY (the designer of the EPP Eagle) said, that motor really isn't up to the job. Depending on how you propped it, it would burn out sooner or later, just by doing a normal climb to altitude.

A motor weighing 70g-100g would not be out of place on a plane as big as the EPP Eagle, though a good quality 45g motor, with low Rm, would do well enough.
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Old Jan 12, 2009, 04:49 PM
Addicted to flight since 1944
rbrown3rd's Avatar
southern Florida
Joined Feb 2004
1,750 Posts
Ok, repowered. I will test fly in the morning weather permitting. I secured those motor leads to provide some strain relief and I will try a 9x4 prop.
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Old Jan 12, 2009, 04:53 PM
Addicted to flight since 1944
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southern Florida
Joined Feb 2004
1,750 Posts
Thanks Andy2NO. I appreciate the advice. As I have said I have been building and flying models for fifty years starting with balsa and tissue but foam and electricity are all pretty new to me. I don't really have a feel for the motor sizes and how to match them appropriately to the plane. I am not a power flyer but prefer to just float around at low throttle settings. I am primarily a glider pilot so my knowledge of motors is begging. Thanks to all for your advice and help. I will eventually get the ship powered appropriately.

What are everyone's recommendations. Remember, I don't like high powered flying but rather floating around lazily.

Update. I did find a pretty good glow vs. electric comparison table here.

Quote:
Originally Posted by Andy2No
I may have missed it, but this begs the question, what number of cells and prop were you using?

The BlueWonder is capable of all that, but not for very long at all, due to the low weight. Lightweight motors can only take brief bursts of power before they overheat. I've read other cases of Blue Wonders burning out, flying fairly light planes.

They're really most suitable as a shock flyer motor, where the current is below 3A a lot of the time, and goes over 6A only in very brief bursts - like a quick aerobatic flourish before the tiny lipo those things use gets drained.

The heat created by a motor is I*I*Rm where I is the current and Rm is the armature impedance aka internal resistance of the motor. For a Blue Wonder, the Rm is on the high side. The capacity for a motor to dissipate heat is limited by the weight of metal in the motor. For a BW, that's on the low side.

A short of the wires leaving the motor could well destroy your ESC, but would leave the motor relatively undamaged - apart from possilble scarring at the site of the short.

Shorter version: As FLYPARTY (the designer of the EPP Eagle) said, that motor really isn't up to the job. Depending on how you propped it, it would burn out sooner or later, just by doing a normal climb to altitude.

A motor weighing 70g-100g would not be out of place on a plane as big as the EPP Eagle, though a good quality 45g motor, with low Rm, would do well enough.
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Old Jan 13, 2009, 10:09 AM
Addicted to flight since 1944
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southern Florida
Joined Feb 2004
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I did some quick test flights this morning before the storms started. I flew a number of circuits. Climb, circle for a while. Passes up and down the field and then land. The controller felt warm but not hot The motor was cool to the touch. I found that I could fly around with extremely low throttle settings which I like. I changed to a larger prop too. I used a 9x5 instead of an 8x4. The prop is the black GWS 0947 EP model. Flight is now extremely quiet. I need to restrict full throttle on my transmitter though as the Eagle climbs like a rocket with any thing more than about 15 percent throttle settings.

I think I built in about the right amount of down thrust but maybe too much right thrust. But, to clarify that, at the very low throttle settings necessary to sustain level flight the ship flies about neutral. Higher power settings create a turn tendency. Nice ship. Flies really smoothly with some throttle. Gliding requires a lot of control movement unless you keep the speed up. I am having fun with it.
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Old Jan 14, 2009, 09:40 AM
GRAYSON HOBBY
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Grayson, GA
Joined Oct 2003
1,087 Posts
Quote:
Originally Posted by SailingAlong
Is Grayson still an authorized dealer?
Yes we are, however, the shipping details have changed and we need to find another method.
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Old Jan 14, 2009, 01:15 PM
NaN
Andy2No's Avatar
Manchester, UK
Joined Nov 2005
3,756 Posts
Quote:
Originally Posted by rbrown3rd
I think I built in about the right amount of down thrust but maybe too much right thrust. But, to clarify that, at the very low throttle settings necessary to sustain level flight the ship flies about neutral. Higher power settings create a turn tendency.
I don't think I've ever got that quite right on any plane. I mostly just get it close and learn to live with it.

I've never really worked out whether the thrust angle correction can make it perfect at every throttle setting, or whether it's just to correct for an average. A lot of i.c. pilots I know only ever seem to use full throttle so they'd never notice.

Incidentally, I started learning about motor selection by using Motocalc from http://motocalc.com. Once I got the basics from that, I took to using the free PeakEff graphing system.. Here's an example, using the manufacturers data for the motor I fitted to my EasyStar:

http://www.peakeff.com/GraphKIR.aspx...&title=2212-06

I gave that example because it's one of the few cases where the manufacturers data actually came close to my own measurements I settled on a 6x3 with a 3s lipo. A 6x4 with a 2s lipo woud probably have done quite well enough (change the voltage box to 7V or 6.5V to see the difference, then press Update Graph).

The problem is, they tend to exagerrate how good their motors are by claiming a lower Rm than they really have. A lot of them don't even give the figures you need. There are just four figures needed to describe any brushless motor:

weight
Io (idle current)
Rm (armature winding impedance aka internal resistance)
Kv (rpm per volt, unloaded)

If manufacturers all gave us those figures, accurately, choosing motors would be an exact science. As it stands, recommendations are probably better, provided they're from people who've taken the time to measure the WOT current and rpm with the prop they're recommending to go with it.

I have a little box full of motors I've chosen for things based on the manufacturers spec, but had to put aside for other projects once I'd measured how they really perform.

Incidentally, balsa and tissue is still largely a mystery to me. It was the way things were built when I was a kid but I never really got to learn how it was done. I'm more comfortable with foam now. The weight saving seems well worth putting up with the shortcomings (like rigidity or fragility). Also, crashing even a polystyrene plane doesn't necessarily mean the end of it. Provided you get most of the big pieces, you can usually fix it with gorilla glue.
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Old Jan 14, 2009, 03:53 PM
Addicted to flight since 1944
rbrown3rd's Avatar
southern Florida
Joined Feb 2004
1,750 Posts
Quote:
Originally Posted by Andy2No
I don't think I've ever got that quite right on any plane. I mostly just get it close and learn to live with it.

I've never really worked out whether the thrust angle correction can make it perfect at every throttle setting, or whether it's just to correct for an average. A lot of i.c. pilots I know only ever seem to use full throttle so they'd never notice.........................

Incidentally, balsa and tissue is still largely a mystery to me. It was the way things were built when I was a kid but I never really got to learn how it was done. I'm more comfortable with foam now. The weight saving seems well worth putting up with the shortcomings (like rigidity or fragility). Also, crashing even a polystyrene plane doesn't necessarily mean the end of it. Provided you get most of the big pieces, you can usually fix it with gorilla glue.
Great info Andy2no. Thanks for those links and for the tips. BTW, I LOVE foam now. I have discovered how tough it is through my own testing. You can guess how that happened. But, as you point out, a bit of polystyrene glue and you are back in business whereas a built up structure would have been totaled. When my "testing" took place I was astonished at how little damage was done and how easy it was to fix it. In the case of the Eagle I just used my hot glue gun to attach a few bits back together and that was that. I know the hot glue is heavy but in the case of my Eagle I didn't consider weight to be an issue and it was in a place where I needed a bit, the nose.
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Old Jan 14, 2009, 04:16 PM
NaN
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Manchester, UK
Joined Nov 2005
3,756 Posts
No problem, rbrown3rd.

Although I no longer use Motocalc I really do recommend it for the educational value. I used it longer than the trial so I paid the license fee. I don't regret it. It was a good investment. Some of its recommendations should probably be taken with a pinch of salt but it definitely helps you get a feel for the subject.

The most basic bit of electric flight equipment is the Watt meter (aka power meter). A good one gives you readings of voltage and current at the same time, and they usually show the watts (V*A) and mAh used so far. That lets you make sure you're operating everything within safe limits.

The next most useful bit of equipment is a tachometer. These days you can get a handheld one very cheaply, which gives you the rpm. That lets you work out the pitch speed (theoretical limiting speed for level powered flight) and gives you an idea whether the plane will be fast enough with that prop, or so fast you won't use full throttle much, or very effectively.

With a few sets of readings from a watt meter and tachometer, you can work out motor constants for yourself (Rm and Kv are the easiest), which helps with prop and motor selection since the manufacturers figures are usually way off. You can also use them to just keep trying different props and measuring the current and rpm til you get it about right, without understanding the theory behind it.

The third bit of kit is a set of digital kitchen scales to get some idea of thrust. It's actually quite hard to measure thrust without good equipment, but a set of scales gives you some idea - you can usually assume you'll get more thrust than you can measure on the bench.

One thing I learned from Motocalc is that props can be stalled if they are too high pitched, which means the static thrust (e.g. measured in a bench test) is quite low. The prop only gives full thrust when it's moving forwards, above a certain airspeed. Props like that are useful for fast planes, but not so useful for powered gliders and slow flyers.

There's a simple rule. If the ratio of the diameter to the pitch is outside the range 3:2 to 2:1, the prop won't work as efficiently or won't give full thrust from a standstill, which makes taking off harder - also makes recovering from a stall by using full power harder. E.g. a 9x6 never stalls but a 9x9 stalls below a certain airspeed. An 8x4 never stalls. I don't think a 9x4 does either, but it's less efficient.

The non-stalling props are now my props of choice, so that affects my choice of motor. When I build something like a small pusher jet, I'll consider using a speed prop, but I won't be able to measure the thrust - the static thrust will be quite low, which is why they're usually such a sod to get airborne from a hand launch.
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Old Jan 18, 2009, 06:52 PM
Registered User
North Liberty, Iowa
Joined Mar 2008
3 Posts
Changing Eagle to wing bolts

I've got a new Eagle ready to start and I'd like to make it a bolt on wing, if I need to add support inside the wing it would be easy now. Can anybody show me what they have done that works well?
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