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FT Explorer question

Aireal Anarchist

Well-known member
#1
FT Explorer question

I am building the Explorer fuselage with a sport wing and box tail, kinda like the large Sky Hunter FPV design, while watching the Explorer build video I see they have the motor pod setup with indication marks so that there is an induced thrust angle.

the explorer is a pusher prop design like many of our flying wings and we do not induce thrust angles on pusher prop flying wings, many of us use a piece of aluminum bent 90 degrees for a motor mount thats it.

in the build video they explain the thrust angle is to prevent the plane from pitching up when giving it throttle so the thrust angle they want us to use compensates and they say it pushes the tail boom down, again I find this confusing that this pusher needs thrust angle and a flying wing pusher does not?

I have watched many YT videos of the explorer and some actually complain the Explorer drags its tail and I agree from the many videos I have watched

then I started viewing scratch built Sky Hunters and I found several that have used the 90 degree motor mount I want to use and no thrust angle?? motors are at the same height in some cases as the Explorer so I am more confused now


so I am going to build it as I wanted with the simple 90 degree aluminum motor mount I use for all my flying wings because there are many successful builds already with successful flights using this method and I dont want to build a tail dragger

but am still thinking about the induced thrust angle to push the tail down ... why does this Explorer pusher model require induced thrust angle and others do not, has anyone built an explorer without the thrust angle if so did it drag the tail?....can anyone shed some light on this before I dive in this project

I suppose if for some reason I cant get my head around I need some thrust I can easily bend the aluminum motor mount


thrust angle.jpg
mtr bracket3.jpg
mtr bracket.jpg
 
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Merv

Well-known member
#2
The motor thrust angle is dependent on how far vertically the motor is above the center of mass. I would stick with the bent metal motor mount.

I struggled with thrust angle on my pusher Versa wing. When I lowered the motor, my thrust angle problems were dramatic improved.
 

Aireal Anarchist

Well-known member
#3
this is what I was thinking ..... the part that confused me the most was as I mentioned above ....the motor height on some of the 90 Degree mounts were at the same height as the explorer pod they didnt seem to tail drag ofcourse the planes I compared the explorer to have very light tails

thanks, I can move forward with more confidence in this issue
 

mrjdstewart

Well-known member
#4
the explorer needs that thrust angle, without it wont fly well. You also need it to help aid the the size of prop you can swing. if you have no angle and put it too low the prop will cut into your tail boom.

good luck,

me :cool:
 

Aireal Anarchist

Well-known member
#5
the explorer needs that thrust angle, without it wont fly well. You also need it to help aid the the size of prop you can swing. if you have no angle and put it too low the prop will cut into your tail boom.

good luck,

me :cool:
thanks for the explanation I kinda understood the principle and why I posed the question because I felt if I induced thrust angle with MY configuration I would be building a plane that drags its tail in flight
so good thing I checked here first cause that wont apply to my build, Im not building an explorer with a raised motor pod to clear a tail boom.
Im building just the explorer fuse with a scaled up Armin sport wing, and the motor mount with a prop shaft LEVEL & less than a 1/2" above the wing surface so no thrust angle is required like the 2 photo examples above. it will have 2 carbon fiber tail booms 16" apart in a box tail config, so I can virtually swing any size prop I want up to 15" dia and I am running a big slow low KV motor:cool:
 
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Hai-Lee

Old and Bold RC PILOT
#6
thanks for the explanation I kinda understood the principle and why I posed the question because I felt if I induced thrust angle with MY configuration I would be building a plane that drags its tail in flight
so good thing I checked here first cause that wont apply to my build, Im not building an explorer with a raised motor pod to clear a tail boom.
Im building just the explorer fuse with a scaled up Armin sport wing, and the motor mount with a prop shaft LEVEL & less than a 1/2" above the wing surface so no thrust angle is required like the 2 photo examples above. it will have 2 carbon fiber tail booms 16" apart in a box tail config, so I can virtually swing any size prop I want up to 15" dia and I am running a big slow low KV motor:cool:
Whilst many people have experience and theories as to why the Explorer has such a high thrust angle the simple truth is that the thrust line is such that it passes through the centre of mass. This allows the plane to handle changes in thrust settings without causing the nose to pitch up or down.

Sadly the thrust angle does mean that there is a small portion of the motor thrust pushing the plane towards the ground but it should not cause the nose to change its pitch angle.

You can alter the thrust angle away from the centre of mass but then the plane will tend to pitch nose down on applying motor thrust and, (if trimmed for level flight under power), to pitch upwards when the motor is cut.

Like all things in aircraft design it is all a matter of compromise.

Have fun!