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Jan 18, 2010, 09:06 AM
Master of Flying Wings......
Discussion

Newest ducted fan build!*******


this is my newest bird, i built her in about 45 minutes using my proven method of deigning. ( See Other Posts )

She should be one heill of a plane!

specs are:

wingspan: 30 in

Fuselage Length: 30 in
V Stabilizer ( L*h) 7.5 X 5 in

H Stabilizer: 10 x 3.5

Ducted fan is right at the nose!.

TELL ME FORUM, DO YOU WANT A VIDEO?????????
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Jan 18, 2010, 10:29 AM
Registered User
Did you build the ducted fan your self ?
Jan 18, 2010, 05:02 PM
Scratch building addict
rotagen's Avatar
I'm definitely interested in ducted fans but never built a model with one. I guess looking at the $$ tag killed it for me, and the thrust from the GWS fans looks pretty wimpy.

Perhaps the pitch speed is so high you don't need as much thrust ? But it seems that the cheap ones can only drive super lightweight models, like under 6 ounces.

Anyone knows better tell me I am wrong......please !?

Cool looking model, I'd like to build a heinkel salamander but I'm a total new-bee with DF stuff.

What fan are u using and whats your total weight? Oh yeah, if you got a vid bring it on !
Jan 18, 2010, 07:45 PM
Master of Flying Wings......
Quote:
Originally Posted by rotagen View Post
I'm definitely interested in ducted fans but never built a model with one. I guess looking at the $$ tag killed it for me, and the thrust from the GWS fans looks pretty wimpy.

Perhaps the pitch speed is so high you don't need as much thrust ? But it seems that the cheap ones can only drive super lightweight models, like under 6 ounces.

Anyone knows better tell me I am wrong......please !?

Cool looking model, I'd like to build a heinkel salamander but I'm a total new-bee with DF stuff.

What fan are u using and whats your total weight? Oh yeah, if you got a vid bring it on !

This airplane underwent a overhauling, i completely changed the nose section and the EDF is on top of the fuselage!

but the thing with DF is that you have to have them above or under the trust line. If its in between then the slightest inch of deflection sends you spiraling.

The salemander would be a good choice.


go to hobbycity.com

look under parts & Acces.

look under EDF'S

look at a 12.00 64mm edf and you should know where to go from there!
Jan 18, 2010, 08:03 PM
Micro Boat Forum Founder
boredom.is.me's Avatar
How does an edf on the thrust line make your plane spiral on surfae deflection? I don't mean to be rude in any way, but don't most df and turbine aircraft have their thrust on the thrustline? What makes them different than a propeller besides the basic airflow at certain points of speed? I am not trying to offend in any way, but was just wondering how you came up with that idea.
Jan 18, 2010, 08:37 PM
Zen in the art of foam
djacob7's Avatar
Yes, I'm curious about the thrust line too.
Jan 18, 2010, 09:55 PM
Registered User
I'm interested as well. Especially because I have a EDF unit sitting at home and I want to build something!!!!

I had it mounted on the back of a hacked up Srtyker wing and had horrible success! It was mounted quite a bit above the wing, I thought it was too far, causing the thrust to push the nose down.

End result, the mount is broken on the EDF unit, so I'm looking at making a design similar to yours that will not require the use of the "stick mount".
Jan 19, 2010, 05:23 PM
Master of Flying Wings......
Quote:
Originally Posted by boredom.is.me View Post
How does an edf on the thrust line make your plane spiral on surfae deflection? I don't mean to be rude in any way, but don't most df and turbine aircraft have their thrust on the thrustline? What makes them different than a propeller besides the basic airflow at certain points of speed? I am not trying to offend in any way, but was just wondering how you came up with that idea.
BECAUSE!

i had it off by like 1/8 of an inch and trust me, IT AFFECTS IT!!

Also the low wing on the aircraft makes it naturally unstable!
Jan 19, 2010, 05:24 PM
Master of Flying Wings......
Quote:
Originally Posted by Tripod333 View Post
I'm interested as well. Especially because I have a EDF unit sitting at home and I want to build something!!!!

I had it mounted on the back of a hacked up Srtyker wing and had horrible success! It was mounted quite a bit above the wing, I thought it was too far, causing the thrust to push the nose down.

End result, the mount is broken on the EDF unit, so I'm looking at making a design similar to yours that will not require the use of the "stick mount".
Look at my posts about how i make my airplanes and you feel free to ask me questions.

Ducted fans perform best on top of a wing about 1/4 behind the LE

also ducted fans like high wing aircraft!
that is, for scratch built
Jan 19, 2010, 06:09 PM
Retardedly intelligent
foam and tape's Avatar
Quote:
Originally Posted by flyingwing12 View Post
BECAUSE!

i had it off by like 1/8 of an inch and trust me, IT AFFECTS IT!!

Also the low wing on the aircraft makes it naturally unstable!


BECAUSE, what care to explain. It dosen't make any sense. If you want a true explanation visit the EDF section of this forum.
Jan 20, 2010, 04:35 AM
Registered User
Did your original design constrict the airflow after the fan? I mean, was the "exaust" port at the back of the plane smaller than the "exaust" port on the EDF unit itself?
Jan 20, 2010, 09:09 AM
Zen in the art of foam
djacob7's Avatar
I doubt the thrust line theory. An EDF will have the same thrust line characteristics as a regular prop. All it needs is a clear path for the air to enter an exit its housing.
Jan 21, 2010, 11:09 AM
Master of Flying Wings......
Quote:
Originally Posted by Tripod333 View Post
Did your original design constrict the airflow after the fan? I mean, was the "exaust" port at the back of the plane smaller than the "exaust" port on the EDF unit itself?
no, but the reason it stalled out, i came to it,

it was to slow!

The air had to travel to far a distance and it stalled to quickly
Jan 21, 2010, 06:41 PM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Quote:
Originally Posted by flyingwing12 View Post
L
Ducted fans perform best on top of a wing about 1/4 behind the LE

also ducted fans like high wing aircraft!
that is, for scratch built
I'm sorry, but both of those statements are so wrong. Take a look at any fighter jet. Ask the guys in the jet forum if you're having design problems.

By definition the thrust line bisects the motor or shaft if it has one. You could be off on the thrust angles in relation to the center line of the aircraft. Is that what you meant?

Plus, it's really not necessary to start so many threads with the same subject, even if they are in different forums, the answers you get just get diluted, not to mention that it's really against the rules.


Azarr
Last edited by Azarr; Jan 21, 2010 at 06:56 PM.
Jan 22, 2010, 09:13 AM
Master of Flying Wings......
Quote:
Originally Posted by Azarr View Post
I'm sorry, but both of those statements are so wrong. Take a look at any fighter jet. Ask the guys in the jet forum if you're having design problems.

By definition the thrust line bisects the motor or shaft if it has one. You could be off on the thrust angles in relation to the center line of the aircraft. Is that what you meant?

Plus, it's really not necessary to start so many threads with the same subject, even if they are in different forums, the answers you get just get diluted, not to mention that it's really against the rules.


Azarr

yes through all the jibberish thats what i was trying to say!.

and yes my friend

jets with the fan on top like to balance at 1/4, 1/3 of the wing.

swept back wings are about 1/2

and foward swept is something like 1/4 from the back i think.
Last edited by flyingwing12; Jan 22, 2010 at 10:06 AM.


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