F-117 FlatHawk (Twin Engine)

[Aero_Knight]

Went with a different approach with my original F-117 design. I used a larger scale and put a second motor on it for 3-4” push props. I went with elevons similar to the Flitetest F-22 instead of standard aileron elevator setup like my original. I am still tinkering with my old design but this seems like a better one overall. The pieces will actually fit together rather snug without glue although flying it that way is not advised. Maiden flight will be sometime tomorrow afternoon hopefully. Tell me what you think!

 

[FoamyDM]

It seems like a profile flyer but with some meat to it. I look forward to it's flight.

is this a high-alpha flyer, or is there a KfM foil?

 

[Aero_Knight]

It seems like a profile flyer but with some meat to it. I look forward to it's flight.

is this a high-alpha flyer, or is there a KfM foil?

Around 6pm(EST) tonight, I will know how it flies LoL. The top wing surface is flush between the front sections and rear half. The bottom is stepped one thickness near the back. You might be able to see it in the second photo. So if anything its similar to a flat KfM-1 style. I am kind of hoping it has similar qualities to the F-22. It is heavier since it has 2 motors and a 1300mAh 3 cell instead of an 800mAh battery. I am not sure where the CG needs to be with this profile yet. It's currently about 2 inches forward of the seam on the wing but a few tosses should tell me if that's right before the flight. I may have to slightly up the prop size (max would be 4") depending on how it goes but bench runs tell me at 50% throttle she wants to go. Control surfaces should be better than the F-22 especially up elevator since its semi-ducted so she should definitely be able to do some high-alpha if the thrust happens to be decently balanced between the motors.

 

[Aero_Knight]

Updated the CAD model I made to include some changes from the first build process. If flight goes well, I will post the patterns. Takes 3 and a half 24"x30" (3/16") foam sheets for reference. Dotted line circles are 4.25" diameter prop circles.

 

[Aero_Knight]

It seems like a profile flyer but with some meat to it. I look forward to it's flight.

is this a high-alpha flyer, or is there a KfM foil?

I'll post video later but I would say she needs more space than my front yard LoL. Wants to go fast. Doesn't have enough power for high AoA and CG needs to move another inch or so forward. Need to replace the nose as the maiden (which of course I didn't get video of) it climbed and then decided to nose dive. A bit more trimming and she should fly great.

 

[Aero_Knight]

F-117 FlatHawk Test Flight

 

[Aero_Knight]

Here is the first draft patterns for the F-117 FlatHawk. Assembly BEFORE gluing to make sure you get the folds right. I forgot to note what should be A and what should be B folds. Most should be I think B folds but fit check to be sure. The vertical tail sections are the only tricky bit to assembly as you have to slot the forward section at an angle (hence the 45 degree chamfer) then rotate the back into place as you push it into the slots. There may be some wiggle room so adjust as needed. The nominal CG should be located at least 2-4" ahead of the wing seam for reference. She can take two standard firewall power packs with 3-4.25" props or with minor mods, a single center power pack. Just cut the tab in the center of the tail section and raise the vertical pieces up until you can handle the prop you want OR remove the vertical pieces entirely as I think the ducting from the side sections and fins on the control surfaces may work to stabilize yaw just fine. Use BBQ skewers to hold packs into place. I used Power Pack F twin motor set with a 3 cell 1300mAh. I recommend using 9g servos but the holes I have cut out are for 5g so you can make adjustments as needed. Have fun!

NOTE: I forgot the cut line for the control surfaces but that should be fairly obvious ;P

I will post an assembly animation at some point that I had made.