WattFlyer RC Electric Flight Forums - Discuss radio control eflight

WattFlyer RC Electric Flight Forums - Discuss radio control eflight (http://www.Wattflyer.com/forums/index.php)
-   General Electric Discussions (http://www.Wattflyer.com/forums/forumdisplay.php?f=3)
-   -   How many Watts are you running? (http://www.Wattflyer.com/forums/showthread.php?t=73689)

kyleservicetech 05-05-2014 03:41 AM

How many Watts are you running?
 
Multiple choices are allowed!

It might be interesting to run a poll on how many watts your models are pulling. No matter what brand motor, just the information.

My models vary all the way from twenty watts to 3000 Watts. The propeller on that 3KW model weighs more than that little Beast Bipe!

Wrongway-Feldman 05-05-2014 04:22 AM

Most of what I fly is around 200 to 500 watts. Have one edf producing around 900.
After next winters planned builds I'll have 2 or 3 models producing around 1500 watts.

kyleservicetech 05-05-2014 05:31 AM

Quote:

Originally Posted by Wrongway-Feldman (Post 947374)
Most of what I fly is around 200 to 500 watts. Have one edf producing around 900.
After next winters planned builds I'll have 2 or 3 models producing around 1500 watts.

Yeah
Running all sorts of models from little to "danged big", for larger models IMHO, the 1200-1500 Watt models are approaching the reasonable limit for electric power.

Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222

Hacker 6S2P A123 powered Models
http://www.wattflyer.com/forums/showthread.php?t=44686

Hangar 9 Kantana Model
http://www.wattflyer.com/forums/showthread.php?t=68844

Going past that 2500 Watt or more level, and the cost skyrockets. You need a pile of $$$$ batteries if you want more than one flight a day. If you go the overweight, oversized, undervoltage A123 cells, they work nicely, but field charging them is a problem. Charging a 12S2P A123 pack in 15 minutes is not compatible with using a 120 Amp Hour deep cycle battery for the charging supply.

JetPlaneFlyer 05-05-2014 06:43 AM

I've got a couple of Helis that pull over 3000W (so I voted 'over 3000') but my fixed wing models are all less than 1500W.

kyleservicetech 05-05-2014 06:50 AM

Quote:

Originally Posted by JetPlaneFlyer (Post 947392)
I've got a couple of Helis that pull over 3000W (so I voted 'over 3000') but my fixed wing models are all less than 1500W.

Lol 3000 watts is 3000 watts no matter what kind of model.

thepiper92 05-05-2014 07:15 AM

Uh oh cant change my answer, I wanted to select two

solentlife 05-05-2014 07:22 AM

mmmm I have models of ordinary 100 - 150W ... and others of over 1200W .. so answering in the ranges you have is not so easy ...

Nigel

kyleservicetech 05-05-2014 07:36 AM

Quote:

Originally Posted by solentlife (Post 947403)
mmmm I have models of ordinary 100 - 150W ... and others of over 1200W .. so answering in the ranges you have is not so easy ...

Nigel

Yeah
I thought of putting in 15 choices, but thought that was overkill.

solentlife 05-05-2014 07:50 AM

Quote:

Originally Posted by kyleservicetech (Post 947408)
Yeah
I thought of putting in 15 choices, but thought that was overkill.

Sorry posted that before realising that more than one choice can be made.

Nigel

kyleservicetech 05-05-2014 07:55 AM

Quote:

Originally Posted by solentlife (Post 947414)
Sorry posted that before realising that more than one choice can be made.

Nigel

Good point multiple choices ARE allowed.

Larry3215 05-05-2014 08:10 AM

They are not all in flying condition, but I have at least one model in every category :)

Larry3215 05-05-2014 08:26 AM

This is a bit off topic, but this topic made me wonder about something.

Denny - what is all up the weight of that 3 watts model of yours? Im curious about the power loading on that small a model.

People usually talk about watts/pound with the idea that more is better. A few years ago I did some experimenting with e-powered sailplanes trying to see how small and light a power system I could get by with. The idea being to climb and soar with an electric motor but with NO weight penalty over the "pure" sailplane version.

My under 50 watt model is an old 2x6 sailplane I salvaged from the trash heap for my grandson. Turns out he wasnt interested because it wasnt a jet powered model :D

I used it to experiment with very low power loadings.

Anyway, that model weighed around 30 oz or so and I flew it on as little as 24 watts and was actually able to climb - if I was very patient and gave it a good hard toss and didnt stall it! :)

That works out to about 13 watts/pound. It turned out that somewhere around 25 watts per pound was a much safer minimum.

Anyway, Im curious what the watts per pound were on your 3 watt model and/or if anyone has tried flying at a lower power loading?

solentlife 05-05-2014 09:00 AM

Larry .. you make a good point and is why I am always a bit sceptical of the watts per lb numbers ...

The variance comes down to wing loading and lift coefficients .. have a light wing loading, high lift coefficient and that Watts per lb figure goes out the window as you found.

Such figures are only really relevant for general sport ... as there are many either side of that which do not conform.

Nigel

Siberianhusky 05-05-2014 01:57 PM

I've got a couple boats pulling about 2500 watts on 4s 10000mah with a Castle 1515 1y 2200kv 300amp esc.
My spec class boats pull about 1500 watts on 4s 5000mah, the "spec" part is we are only allowed a few specific motors. Those ones I'm putting about 100 amps through a motor rated for 60, even with water cooling they come in close to the max temps you want to see on a motor. Burnt up more than a few, demagnetized some....

Planes are 50-300 watts. All basically trainers and one wing, only been flying a year, think this is my 31st season on rc boating.

kyleservicetech 05-05-2014 03:51 PM

[QUOTE=Larry3215;947421]This is a bit off topic, but this topic made me wonder about something.

Denny - what is all up the weight of that 3 watts model of yours? Im curious about the power loading on that small a model.

People usually talk about watts/pound with the idea that more is better. A few years ago I did some experimenting with e-powered sailplanes trying to see how small and light a power system I could get by with. The idea being to climb and soar with an electric motor but with NO weight penalty over the "pure" sailplane version.

My under 50 watt model is an old 2x6 sailplane I salvaged from the trash heap for my grandson. Turns out he wasnt interested because it wasnt a jet powered model :D

I used it to experiment with very low power loadings.

Anyway, that model weighed around 30 oz or so and I flew it on as little as 24 watts and was actually able to climb - if I was very patient and gave it a good hard toss and didnt stall it! :)

That works out to about 13 watts/pound. It turned out that somewhere around 25 watts per pound was a much safer minimum.

Anyway, Im curious what the watts per pound were on your 3 watt model and/or if anyone has tried flying at a lower power loading/QUOTE]

Oh crap, its 3 amps not 3 watts:oops:. That should be 21 watts.

At any rate there are people flying those micro micro things on less than one watt. Those models are extremely fragile.

kyleservicetech 05-06-2014 01:43 AM

Quote:

Originally Posted by solentlife (Post 947424)
Larry .. you make a good point and is why I am always a bit sceptical of the watts per lb numbers ...

The variance comes down to wing loading and lift coefficients .. have a light wing loading, high lift coefficient and that Watts per lb figure goes out the window as you found.

Such figures are only really relevant for general sport ... as there are many either side of that which do not conform.

Nigel

Yeah, there is a very big difference in required watts per pound to fly a very efficient sail plane, versus one of those 100 MPH plus ducted fan jets.

Some of those sailplanes probably could fly at 10 - 15 MPH. Go from that to an 80 MPH model and the power to fly increases at the third power of the speed. That's something around 100 times more horses up front for roughly the same size model.

This is where one of those computer programs for model airplanes comes in handy. One good one is www.motocalc.com. Problem is with motocalc, it's only as accurate as the specs provided by the motor mfg. Some of those specs are not worth the paper they are written on.

For those that are wondering about the power input to a propeller, APC props has tables on their products on this very subject. the APC prop numbers are very close to the motocalc results for power input.
http://www.apcprop.com/v/downloads/P...B/datalist.asp

solentlife 05-06-2014 07:19 AM

Hi Denny .. I know you are a fan of Motocalc ... and that's fine if you use what they list.

But for me - it's not much use .. I do look at it now and again to see if any info .. and I would say it's good for 2 out 5 calcs for me. ? - I don't have access to many of the motors / info it lists / needs.

Nigel

kyleservicetech 05-06-2014 07:24 AM

Quote:

Originally Posted by solentlife (Post 947522)
Hi Denny .. I know you are a fan of Motocalc ... and that's fine if you use what they list.

But for me - it's not much use .. I do look at it now and again to see if any info .. and I would say it's good for 2 out 5 calcs for me. ? - I don't have access to many of the motors / info it lists / needs.

Nigel

Hi Nigel
Yeah motocalc doesn't have all the mfgs. What I do is look up the motor specs on line and plug them in motocalc.
A lot of motors don't provide winding resistance. That's a pain in the ...

kyleservicetech 05-12-2014 06:36 AM

This poll is still active!
 
Lets see if we can get a few more votes to this poll. :D :D :D

hayofstacks 05-13-2014 05:11 AM

I voted for the under 500watt category as all but one of my planes and all my park flyers fit in there.


All times are GMT +1. The time now is 11:33 AM.

Powered by: vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Page generated in 0.09075 seconds with 13 queries