SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Dec 09, 2012, 06:34 AM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
10,926 Posts
That NTM 2200kv motor will be the main shortfall. It can't do that power level. It is about "600W area capable".
The L2855-2300kv is a lot different, able to do 1100w effectively... and survive.

I am using the L2855-2300kv with Zippy 3000mAH 20C predominantly, for 1030g Thrust in the Vampire, with no alteration to the cheaters or ducting at all. It powers a 1.5Kg Vampire totally fine - adequate for realistic flight speeds and motions.

Though a few people lately have posted very low numbers off known better performing combos. Which no one seems to have ever followed up on what or why truly happened with those. (More so on 4S 2800kv combos).

In the Vampire I fly (approx by timer) the 3000MAh down to 800mAH left, for approx 3.5mins to 4.0mins total flight time (take-off initiation to landing and then motor off). The 20C Zippy's are 'medium warm', and certainly nothing detrimental to them. The typical WOT current is 43Amps (in the Vampire).
In my Meteor the exact same setup runs at 50Amps WOT, seeing it has a more free flowing ducting syste, and thus more thrust too. If I fly it a high throttle setting all flight (which I used to do all the time) the 20C Zippy's come down "quite hot" - not puffed, but occassionally they are - and I consider them on the verge of too hot to be good for them. So when I use them in the Metoer I don't use a lot of WOT. 30C in that will come down 'warm" and coping easily, and run it at a bit higher power level too.

So the 20C Zippy's are excellent pairings for the CS10 with L2855-2300kv - in a "medium" performance aircraft! (because it keeps their Amps lower). Certainly perfect for the Vampire.

Throw that 2200kv NTM 'away'... into some prop drive aircraft. It is far more suited to that task.
PeterVRC is online now Find More Posts by PeterVRC
RCG Plus Member
Last edited by PeterVRC; Dec 09, 2012 at 06:40 AM.
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 09, 2012, 06:38 AM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
10,926 Posts
You sneaked in your post about the ESC timing.....
Well at least you got something useful out of it! I hope you mean 58Amps on the BENCH!
That will drop significantly in the Vampire, which you WANT to happen! Or else the motor won't last long! Plus the 20C Zippy would not like that either!
You want it to be about 900Watts area. That will be around 43Amps area in that combo. But I think that motor won't even like that level too much.

At 1300g AUW, even 1000g thrust will be plenty.

Use that combo, but just keep tabs on the motor heats after landing. I guess it would be interesting to see how long it lasts... hehe
I tested one and never used it for a plane, it seemed unlikely to be workable long term.
PeterVRC is online now Find More Posts by PeterVRC
RCG Plus Member
Latest blog entry: FPV Cameras & fixed or pan/tilt
Reply With Quote
Old Dec 09, 2012, 10:14 AM
Registered User
anlucas's Avatar
Greece, Attica, Athens
Joined May 2011
3,335 Posts
Quote:
Originally Posted by warbirdzfan View Post
Thanks for that info. I changed my ESC timing from low to high & got more respectable figures out of the 2200kv NTM Prop Drive. 1022 watts @ 58 amps on a 3000mah 5s. I'll test this in my Vampire tomorrow & suspect it will give a satisfactory result until my ordered L2855 2300kv motor arrives.
That sounds good!. I always run these outrunners on low timing. Amps/watts go down but thrust stays the same.
anlucas is offline Find More Posts by anlucas
Reply With Quote
Old Dec 09, 2012, 03:17 PM
Registered User
warbirdzfan's Avatar
Australia, QLD, Woody Point
Joined Aug 2011
88 Posts
Quote:
Originally Posted by PeterVRC View Post
You sneaked in your post about the ESC timing.....
Well at least you got something useful out of it! I hope you mean 58Amps on the BENCH!
That will drop significantly in the Vampire, which you WANT to happen! Or else the motor won't last long! Plus the 20C Zippy would not like that either!
You want it to be about 900Watts area. That will be around 43Amps area in that combo. But I think that motor won't even like that level too much.

At 1300g AUW, even 1000g thrust will be plenty.

Use that combo, but just keep tabs on the motor heats after landing. I guess it would be interesting to see how long it lasts... hehe
I tested one and never used it for a plane, it seemed unlikely to be workable long term.
Hmmm! Back to softer timing sounds like the safer option then if it's not going to make much difference to the thrust. The NTM motor is expendable but I would like it to last at least until the new L2855 2300 arrives. According to the Hobbyking site the NTM motor is rated for 696 watts with max of 50 amps. The 1033 watts @ 58 amps I obtained on the power analyser was peak & should drop considerably once the plane is airborne. If the motor survives its ordeal I will put it into my Multiplex Funjet pusher for an easier life on 4s
Thanks again to you guys for helping me with this. Most of my previous motor/prop experience has been with my 30 or so prop driven aircraft. There are just so many more extra factors to consider with EDF installations than I had ever previously appreciated!
As an aside. I am already enviously looking at the new Durafly Sea Vixen. Not sure how that will go in terms of efficiency with its twin exhaust outlets!

P.S. I just got back from the field after testing the Vamp with the NTM 2200 on 5s. I pulled the timing back to medium beforehand. It performed quite well & seemed to have more thrust than the previous L2855 2800 on 4s. No overheating but it was only the one flight. The only downside was that the NTM motor is noisy & the subdued jet whoosh seemed to be missing. Oh well, guess I'll have to be patient until the new L2855 2300 arrives.
It now also occurs to me that I previously trialled the L2855 2800kv 4s setup on low timing. That unit might also be worth revisiting with timing set to medium or high.
warbirdzfan is offline Find More Posts by warbirdzfan
Last edited by warbirdzfan; Dec 09, 2012 at 06:16 PM.
Reply With Quote
Old Dec 09, 2012, 08:45 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
10,926 Posts
I always use high timing on them all.... I didn't see any savings on lower timings. A good as zero change seen. (probably was an Amp here or there)
But I do keep meaning to go over those tests again to be sure....
PeterVRC is online now Find More Posts by PeterVRC
RCG Plus Member
Latest blog entry: FPV Cameras & fixed or pan/tilt
Reply With Quote
Old Dec 10, 2012, 03:59 AM
Registered User
warbirdzfan's Avatar
Australia, QLD, Woody Point
Joined Aug 2011
88 Posts
Quote:
Originally Posted by PeterVRC View Post
I always use high timing on them all.... I didn't see any savings on lower timings. A good as zero change seen. (probably was an Amp here or there)
But I do keep meaning to go over those tests again to be sure....
Flew the Vamp again this afternoon with the L2855 2800kv 4s with timing set to high. Pleased with the result. Plenty of power & quiet enough to get the desired sound effect.
warbirdzfan is offline Find More Posts by warbirdzfan
Reply With Quote
Old Dec 10, 2012, 05:29 AM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,592 Posts
Quote:
Originally Posted by anlucas View Post
That sounds good!. I always run these outrunners on low timing. Amps/watts go down but thrust stays the same.
+1, burnt a few esc's on high timing due to the amp draw.

Eric B.
AirX is offline Find More Posts by AirX
Reply With Quote
Old Dec 10, 2012, 01:39 PM
3DHOG
jcdfrd's Avatar
USA, CA, Aromas
Joined Sep 2010
4,848 Posts
Nicks new Projet A10 with 10 blade 70mm twins, this one flys so much better than the first one.
sorry about the drama going on in the background lol!!

Nicks Projet A10 (5 min 43 sec)
jcdfrd is offline Find More Posts by jcdfrd
Reply With Quote
Old Dec 11, 2012, 10:32 AM
Registered User
The43rdHammer's Avatar
United Kingdom
Joined May 2010
366 Posts
That's really nice, great video.... some at your field might say "really f**king nice, dude!"
The43rdHammer is offline Find More Posts by The43rdHammer
Reply With Quote
Old Dec 11, 2012, 10:36 AM
3DHOG
jcdfrd's Avatar
USA, CA, Aromas
Joined Sep 2010
4,848 Posts
oh thats a good one hammer lol!!!!
thanks
jcdfrd is offline Find More Posts by jcdfrd
Reply With Quote
Old Dec 11, 2012, 02:02 PM
Big gov never Works
St. Martin's Avatar
Skunk Water, Rhode Island
Joined Jul 2002
12,327 Posts
Quote:
Originally Posted by anlucas View Post
That sounds good!. I always run these outrunners on low timing. Amps/watts go down but thrust stays the same.
I'm not trying to be critical. But how can thrust dynamic or static remain the same, if amp and watts are down? Sorry..just don't get it. Unless you mean unnoticeable?

Fuzz
St. Martin is online now Find More Posts by St. Martin
Reply With Quote
Old Dec 11, 2012, 03:52 PM
Registered User
Australia, VIC, Melbourne
Joined Nov 2006
10,926 Posts
Well, if things are not optimal you can burn power for no benefit.
eg If the next pole cycle of the waveform starts too early then is is opposing the armature direction for a short period before the armature passes it truly optimal point to gain from that 'power'.
Very much identical to advancing a combustion engine too much - the fuel mixture fires as the piston is still coming up and thus opposes the rise, befor it ever got to the truly optimal point for it to fire.
In both of those cases you do 'fire' earlier than TopDeadCentre, because the combusion process takes a bit of time, and in electric motor the electromagnetic field build up takes time... so you have to begin the process X amount earlier than where you want the full 'effect' to have been reached... but not 2X, 3X earlier or it is detrimental.

This is what the Timing setting in your ESC does... High = higher, timing advances that beginning of the process. The 7deg, 15deg etc is how much armature rotation to 'fire' ahead of the point you want the maximum field to be reached - so that the field build up completes right at that optimal time.
Advance too far.. and it is detrimental.
The outcome of the balances can be anything.... eg to use more power for zero output difference... or use more power for LESS output result etc etc.

Thus... it IS possible to use less amps INPUT for more power OUTPUT. Or.... more power INPUT for less power output.
(comparing the same system with various timing advance settings)
PeterVRC is online now Find More Posts by PeterVRC
RCG Plus Member
Last edited by PeterVRC; Dec 11, 2012 at 06:53 PM.
Reply With Quote
Old Dec 11, 2012, 04:54 PM
Life begins at transition
Australia, VIC, Sale
Joined May 2007
3,593 Posts
mmm, toasty motor!
Odysis is offline Find More Posts by Odysis
Reply With Quote
Old Dec 11, 2012, 07:15 PM
Registered User
WhalleyB0Y's Avatar
Canada, BC, Surrey
Joined Jul 2011
893 Posts
Quote:
Originally Posted by PeterVRC View Post
Well, if things are not optimal you can burn power for no benefit.
eg If the next pole cycle of the waveform starts too early then is is opposing the armature direction for a short period before the armature passes it truly optimal point to gain from that 'power'.
Very much identical to advancing a combustion engine too much - the fuel mixture fires as the piston is still coming up and thus opposes the rise, befor it ever got to the truly optimal point for it to fire.
In both of those cases you do 'fire' earlier than TopDeadCentre, because the combusion process takes a bit of time, and in electric motor the electromagnetic field build up takes time... so you have to begin the process X amount earlier than where you want the full 'effect' to have been reached... but not 2X, 3X earlier or it is detrimental.

This is what the Timing setting in your ESC does... High = higher, timing advances that beginning of the process. The 7deg, 15deg etc is how much armature rotation to 'fire' ahead of the point you want the maximum field to be reached - so that the field build up completes right at that optimal time.
Advance too far.. and it is detrimental.
The outcome of the balances can be anything.... eg to use more power for zero output difference... or use more power for LESS output result etc etc.

Thus... it IS possible to use less amps INPUT for more power OUTPUT. Or.... more power INPUT for less power output.
(comparing the same system with various timing advance settings)
Excellent explanation! I would even go as far as to say the watts seen in a wattmeter could mean nothing if the the energy is being wasted in the form of heat or other electrical losses. The true measurement in this case would be the thrust.
WhalleyB0Y is offline Find More Posts by WhalleyB0Y
Reply With Quote
Old Dec 11, 2012, 09:59 PM
Registered User
anlucas's Avatar
Greece, Attica, Athens
Joined May 2011
3,335 Posts
Quote:
Originally Posted by St. Martin View Post
I'm not trying to be critical. But how can thrust dynamic or static remain the same, if amp and watts are down? Sorry..just don't get it. Unless you mean unnoticeable?

Fuzz
If we had the ideal motor with super strong magnets/magnetic field, rpm/thrust would be directly proportional to amps/watts.

But, this is not the case with some of these outrunners. At some point they reach a point where the surplass energy just becomes heat rather than rotational energy. The thrust differences can be below 100gr.
anlucas is offline Find More Posts by anlucas
Last edited by anlucas; Dec 12, 2012 at 03:29 AM.
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product Change Sun 12 blade 90mm Flip Flop Electric Ducted Fan Jet Talk 7081 Jul 28, 2014 08:25 AM
New Product Change Sun 120mm and new 10 blade 70mm fans Flip Flop Electric Ducted Fan Jet Talk 131 Apr 27, 2012 07:07 PM
Sold Change Sun electric retracts Flip Flop Aircraft - Electric - Jets (FS/W) 3 May 23, 2011 06:20 AM
Sold Change Sun Electronic retracts w/Lander struts hole digger Aircraft - Electric - Jets (FS/W) 2 May 06, 2011 01:27 PM
Sold Change Sun Electric retracts NIB 75.00 jzuniga Aircraft - Electric - Jets (FS/W) 2 Sep 03, 2010 09:36 AM