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Old Dec 11, 2012, 02:37 PM
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United States, TX, Lubbock
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Quote:
Originally Posted by GryphonRCU View Post
Hi Murdo,

Fantastic video. I had to watch it twice in a row.
....just wow.

22/50 next ???? Oh my god.

Among the various options, consider this one too:
Drop 1 cell count on the MEGA you have in there now, and try over pitch prop.
......yeah yeah, I know that you supposedly will get more torque roll, but worth trying to see what happens.

-----

You already have a 22/60. I assume the reason you are not going with that is due to C.G.


I better go watch your video again.

Gryphon
I think the Demon could carry the 22/60.
The 22/60/1.5SE I have is a low KV, though. It would need 12S and 7.4" Q40 props to take advantage of the motor's power.
My Demon is cut out for 9S 4400mah. 12S can still be made from three 4S packs, but the only 4S packs that would be thin enough would be too low capacity to deliver the amps.

EDIT:
6S will be the ticket. Only running 7S because it's what I have at the moment. But another 3S pack is not far off so I'll be able to make 6S. It'll fit much better, too, as the plane wasn't built to hold any 4S 4400 packs.

Square or oversquare props like 6.5x6.5, 7x7 and 7x9 are the ticket to straight line speed on airframes like this.
Can't run 7x7 on the 22/30/1.5SE with 7S, so 6S and 7x8 or 7x9 will be the sweet spot for around 200mph airspeed.
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Old Dec 11, 2012, 09:40 PM
Flirtin With Disaster !!
D.B. Hooper's Avatar
United States, OR, Mt Angel
Joined Jan 2008
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Thinking of the 16/45/1.5 2150kv for the Demon. Any comments before I order
http://www.megamotor.cz/v4/script/de...ge_id=lang_eng
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Old Dec 11, 2012, 09:56 PM
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Link isn't working, so sorry I can't see just which motor you're referring to.
Mega's site logs you out after a few minutes.

There is no 16/45/x motor at 2150kv.

The only way you'd be gambling with a Mega (from above post) is if you got one that didn't suit your needs.

The 16/45/1.5R is 2102kv.
I do think that one would suit your needs well.
It won't be running on the edge, but will still get you the power you're looking for.

The 16/45 motors are 50g heavier than the Rokett you've been running. You may have to add 1oz to the nose to balance if you can't move batteries forward any more.

For a direct swap-in at the same weight, the 16/35/1.5SCE would suit well at 2060kv.

I assume you'd want the 5mm Combat shaft option
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Old Dec 11, 2012, 10:03 PM
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USA, ID, Niter
Joined Jul 2008
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I have a Mega on my TL50. Absolutely bullet proof.
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Old Dec 11, 2012, 10:05 PM
Flirtin With Disaster !!
D.B. Hooper's Avatar
United States, OR, Mt Angel
Joined Jan 2008
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Quote:
Originally Posted by murdnunoc View Post
Link isn't working, so sorry I can't see just which motor you're referring to.
Mega's site logs you out after a few minutes.

There is no 16/45/x motor at 2150kv.

The only way you'd be gambling with a Mega (from above post) is if you got one that didn't suit your needs.

The 16/45/1.5R is 2102kv.
I do think that one would suit your needs well.
It won't be running on the edge, but will still get you the power you're looking for.

The 16/45 motors are 50g heavier than the Rokett you've been running. You may have to add 1oz to the nose to balance if you can't move batteries forward any more.

For a direct swap-in at the same weight, the 16/35/1.5SCE would suit well at 2060kv.

I assume you'd want the 5mm Combat shaft option
Yes that's the one I meant! the 16/45/1.5 R 2102kv 5mm on 7s with the 6.5 carbon prop
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Old Dec 11, 2012, 10:29 PM
Molon Labe
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United States, CA, San Luis Obispo
Joined Feb 2008
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Hey DB, I have Rocket 28-56-1900 that I may be willing to sell.

I was looking at going 6s for the rocket, but if there is a good MEGA that could be run on 8s with an ICE 100 like Peter M's build, I might want to go that route instead.

Ideas?
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Old Dec 11, 2012, 10:40 PM
Flirtin With Disaster !!
D.B. Hooper's Avatar
United States, OR, Mt Angel
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Quote:
Originally Posted by BpPilot View Post
Hey DB, I have Rocket 28-56-1900 that I may be willing to sell.

I was looking at going 6s for the rocket, but if there is a good MEGA that could be run on 8s with an ICE 100 like Peter M's build, I might want to go that route instead.

Ideas?
Has the Rocket motor been installed and used? What would you want for it?
The Mega 16/45/1.5 2102kv can run up to 9s but you will need a new ESC. I heard of a Ritewing ESC but don't know if they are available?
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Old Dec 11, 2012, 10:43 PM
Molon Labe
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The motor is brand new, never been installed or run. Still has the original solder on the leads...

It may be about a week till I can ship it just fyi. If this is too long, go for a MEGA. I'm sure you would be happy with one anyway!
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Old Dec 12, 2012, 04:09 PM
Molon Labe
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Soooo, what MEGA for 6s-8s?

I'm pretty good with throttle management so it can be pretty high powered. Im planning on doing the build with the angled battery setup so probably no 7s configuration. I would like to be able to run 6s 5000mah and 8s 4000mah if possible. I think that is about what Peter M did on his GT40 build (correct me if im wrong...?)
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Old Dec 12, 2012, 06:23 PM
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Quote:
Originally Posted by D.B. Hooper View Post
The Mega 16/45/1.5 2102kv can run up to 9s
WHAT?!!

9S no way unless you're spinning 4" props. Not on a Demon.

That's 56K RPM. Bad idea.
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Old Dec 12, 2012, 06:34 PM
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United States, OR, Mt Angel
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That was the info from Mega's website.
16/45/1,5R 4-26Ni/ 2-9 LI 2102
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Old Dec 12, 2012, 07:13 PM
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Manufacturers list a few specs for a few of the applications their motors could be used for.
Basic motor math always has to be used to verify if your setup is what they're talking about. In this case, it's not.
The 9S spec could have been an EDF spec, or a 400 pylon. They both run low-load props/fans that take high rpm (high volts) to develop any power.

2102kv x 9S x 3.5V/cell x 85% load = 56,281 RPM
That's what the motor will try to turn the prop at.

We know what happens to a 6x4 prop at over 40K, so that's out.
Even if the 6x4 could handle the rpm and still be efficient (not supersonic tips) it would pull an insane amount of power to turn at 56K.

But on the other hand,
2102kv x 6S x 3.5V/cell x 85% = 37,520 RPM
That's realistic for a 6x4 prop, or a 6x5 prop.
Some data gathering tells me that it takes 1865W to turn the 6x5 at 37,500 RPM.
1865W / 21V = 89 amps.
More data gathering and input from others who have run the 1.5R motor tells me this motor can handle 89A no problem. Even for WOT the whole flight.

16/45/1.5R = Good, safe, high power 6S motor on 6x5 prop!!
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Old Dec 12, 2012, 07:35 PM
Flirtin With Disaster !!
D.B. Hooper's Avatar
United States, OR, Mt Angel
Joined Jan 2008
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Quote:
Originally Posted by murdnunoc View Post
Manufacturers list a few specs for a few of the applications their motors could be used for.
Basic motor math always has to be used to verify if your setup is what they're talking about. In this case, it's not.
The 9S spec could have been an EDF spec, or a 400 pylon. They both run low-load props/fans that take high rpm (high volts) to develop any power.

2102kv x 9S x 3.5V/cell x 85% load = 56,281 RPM
That's what the motor will try to turn the prop at.

We know what happens to a 6x4 prop at over 40K, so that's out.
Even if the 6x4 could handle the rpm and still be efficient (not supersonic tips) it would pull an insane amount of power to turn at 56K.

But on the other hand,
2102kv x 6S x 3.5V/cell x 85% = 37,520 RPM
That's realistic for a 6x4 prop, or a 6x5 prop.
Some data gathering tells me that it takes 1865W to turn the 6x5 at 37,500 RPM.
1865W / 21V = 89 amps.
More data gathering and input from others who have run the 1.5R motor tells me this motor can handle 89A no problem. Even for WOT the whole flight.

16/45/1.5R = Good, safe, high power 6S motor on 6x5 prop!!
Thanks Darren!

I'll call Gary and get the 16/45/1.5 combat ordered (6 weeks)
He does have the 16/40/1.5SEC 1800kv in stock but I think the KV might be to low.
Should I get ceramic bearings?
When I get in the air I'll send a screen shot from the data log. Will get a video with RCspeedo.

D.B
Technical slacker
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Old Dec 12, 2012, 07:48 PM
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Make sure you specify 16/45/1.5RC

There are two different 1.5 turns, and C gets you a 5mm Combat shaft. Don't want to wind up with a bitty 3.17mm shaft. Can't get anything done with that little shaft!!

Mega's standard bearings are tough. They'll survive any crash that doesn't bend the shaft (and it's TOUGH to bend their 5mm shaft)
Ceramic really only becomes a significant benefit over 50K RPM. Won't hurt to have them if you want just that extra tiny edge, or a tiny bit more insurance, but not necessary in this application IMO.

16/40/1.5SCE would be sweet on 7S.
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Old Dec 12, 2012, 08:40 PM
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United States, CA, SF
Joined Mar 2008
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Bearing options:

There is an option between stock bearing and BOCA ABEC 7 Hybrid bearing:

It is the 100,000 RPM bearing.
For people interested; Expect extra $20-$23 charge from a dealer.


Gryphon
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