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Search: Posts Made By: watt_the!
Showing results 1 to 25 of 500
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Forum: Electric RC Jets
04-16-2010, 05:01 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

and here we go....:eek:
Forum: Electric RC Jets
04-14-2010, 09:26 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

i think your first line about sums it up...

the rest is just being exactly what i described- but you couldnt understand.

i have a feeling that you still havent read through this...
Forum: Electric RC Jets
04-14-2010, 05:41 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

a very long bow. the only misinformation is the suggestion that you've made about the universe being flat, which is a speculative hypothesis by scientists, whereas we have photographs of the earth...
Forum: Electric RC Jets
04-13-2010, 11:40 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

maybe try reading the thread before wasting your time.

by all means do your data recording if you must. if it means something to you then thats great. we've covered why its not a useful...
Forum: Electric RC Jets
04-12-2010, 10:18 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

your data will tell you nothing. this has been discussed as to the whys, hows, wheres, ad infinitum throughout the thread.

in fact its most likely to reignite the topic again- despite it being...
Forum: Electric RC Jets
04-11-2010, 03:58 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

well you didnt get that from my post.

interesting conclusion also. conclusion based on zero evidence to support it.
Forum: Electric RC Jets
04-11-2010, 03:14 AM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

ah..icdf..my favourite topic.


the problem with icdf is that each engine puts out a certain power level at a certain rpm..

it has torque and power and a very definite limit at each rpm...
Forum: Electric RC Jets
04-01-2010, 04:01 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

sigh. read the sites again douchebag. i'm sooo glad you arent going to reply again.
Forum: Electric RC Jets
03-31-2010, 10:50 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

looks like its a forum site....from what i can tell.

is this your support of your position?- other joe public's opinion?
Forum: Electric RC Jets
03-31-2010, 10:49 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

http://4wings.com.phtemp.com/tip/tpdduct.html

http://www.pdfone.com/ebook/ducted-fan-design-issues-and-errors.html
(they even mention people like cyclops in this article)

...
Forum: Electric RC Jets
03-31-2010, 04:27 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

now you're just being a jerk.

no one ever said they were EDF "lovers"...merely answering a question.

secondly, nothing is specified in any options favour...its specified to ensure proper...
Forum: Electric RC Jets
03-31-2010, 04:30 AM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

or both have a 2.5"d, 2"p single blader (assume a very light airframe).

im pretty sure all of these calcs can be done using a program like motocalc.. only the coefficients and other theoretical...
Forum: Electric RC Jets
03-31-2010, 04:28 AM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

i still dont think thats a fair comparison. if it was a straight line, then yes.

PS a mig21 isnt a great example either as the intake cone is going to rob the EDF.

the final issue here is...
Forum: RC Scale Aircraft
03-20-2010, 03:29 PM
Replies: 75
Views: 13,534
Posted By watt_the!

RE: proctor eindecker lll reduced to 1/6 scale scratchbuilt

no offence but alot of people might suggest that you already have with the detail you're putting into this thing..;)

its down right amazing.
Forum: Electric RC Jets
03-01-2010, 03:13 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

variable pitch EDF might bridge the gap. but it still suffers from size compromises.
Forum: RC Scale Aircraft
03-01-2010, 01:57 AM
Replies: 75
Views: 13,534
Posted By watt_the!

RE: proctor eindecker lll reduced to 1/6 scale scratchbuilt

woah..very impressive.

ive built 3 eindekkers..1/6th, 1/5th and 1/12th.

fantastic subject.

ive also just got me a avro mkiv tripe that ive been looking for brass parts for..and you've...
Forum: Electric RC Jets
02-28-2010, 10:44 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

i was going to ask the same thing.
Forum: Electric RC Jets
02-28-2010, 09:03 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

wth?..wrong on all counts..and on the airliner count also- which is a turbine anyway and has everything to do with fuel consumption.
Forum: Electric RC Jets
02-28-2010, 08:13 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

i dont think we disagree in fact.

the edf chomps power as its usually crammed into a small space, is in a long duct (fore and aft) and has loads of blades...all contributing to extra losses that...
Forum: Electric RC Jets
02-28-2010, 05:02 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

efficiency is a term used to describe the performance of an object over the entire range of the operating envelope.

so you'd need to integrate the efficiency along its curve in order to...
Forum: Electric RC Jets
02-28-2010, 03:25 AM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

yeah- comparing apples to apples is a big myth generator in E RC...and a real problem.

Like the argument for Volts v Amps. When arguing this, the V proponents compare a system side by side...
Forum: Electric RC Jets
02-28-2010, 12:19 AM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

this is the sum of it.

nice post.

now if we can form a band to work together and convince Joe Public that more power does not mean more efficiency and/or that more power means better...
Forum: Electric RC Jets
02-28-2010, 12:16 AM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

thats because those traits are not core functions of a DF.

using that as basis for the argument is flawed.

Those records sit at the extremes of application and as we know, DFs were born...
Forum: Electric RC Jets
02-15-2010, 03:36 PM
Replies: 81
Views: 11,738
Posted By watt_the!

RE: Why are ducted fans considered so inefficient?

weight was a major issue, and again, diameter. shrouds were impractical.

the point is that shrouds/fans are efficient. marginally moreso than props.

for voyager a shroud has too many...
Forum: Electric RC Jets
02-15-2010, 12:24 AM
Replies: 24
Views: 3,722
Posted By watt_the!

RE: will twin EDF ?

it depends on what rpm you have..but for the record, a larger diam fan puts out more thrust than a smaller one for any given power...but it isnt a noticable difference (need to measure as opposed to...
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