SR-71 BlackBird

[AcendenceRC]

Also thanks for sending the KF airfoil article, really useful.

 

[kilroy07]

Is there a reason to use the negative thrust angle?

Initially it was personal, I wanted to do a decent scale representation of my favorite jet.
But I think there might be something to it now after flight and glide tests.
With the negative thrust angle it will pitch the nose up a bit, keeping the huge flat wing on a positive plane I think.
(I am NOT an aeronautical engineer BTW... Always wanted to be one when I grew up, but that's another story.)

Did NOT mean to throw your project off track, I am really interested in seeing your design come to light as well! (Can't have enough Blackbirds now can we?!)

Also thanks for sending the KF airfoil article, really useful.

 

[BATTLEAXE]

With the negative thrust angle it will pitch the nose up a bit, keeping the huge flat wing on a positive plane I think.

I have a question, only because I know nothing about EDF's. How do you adjust thrust angle when the EDF sits between the intake and thrust tube, is it even effective? Or is it an adjustment of the thrust tube itself?

 

[AcendenceRC]

In this case, i'm pretty sure the thrust tube must be adjusted.

 

[kilroy07]

I adjusted the entire engine pod (as I said, probably the hardest part of the design.)
Maybe this will illustrate;
You can see the cyan lines are skewed, they represent the front and back of the EDF, the yellow was the thrust line.

 

[AcendenceRC]

Very in depth, thank you! I will definitely try experimenting with different thrust angles. Too bad its winter, stuck to building and designing.

 

[BATTLEAXE]

Found a vid for inspiration

 

[AcendenceRC]

UPDATE:
I took a break from the blackbird, working on this short side project.



( F-16 B)

AcendenceRC

 

[BATTLEAXE]

UPDATE:
I took a break from the blackbird, working on this short side project.

View attachment 150443

( F-16 B)

AcendenceRC

That looks really good man, is that just from the 3 view you have on the table? Are you hooking up the stabilators directly to the servo?

 

[AcendenceRC]

That looks really good man, is that just from the 3 view you have on the table? Are you hooking up the stabilators directly to the servo?

It's from both a top down template, and the 3 view. Not sure how I am going to mount the horizontal stabs yet.

 

[AcendenceRC]

Just finished the new F-16B , back to the SR-71, too bad its winter...

 

[AcendenceRC]

UPDATE:
Just acquired a pair of 70mm EDFs, should be plenty of power...

 

[Grifflyer]

Nice, good luck!