SR-71 Prop and Slot

Here is my SR-71 prop n slot build from Balsa Plans. I decided to build it with a flat bottom and work from the delta wing forward.

Here, I added the leading edge and the slot.

Then added the leading wing surface.

Added inboard and outboard elevons using a single pushrod and a central spar to strength the upper wing surface. The esc sits right in the middle and the battery and servo wires run to the nose. I cut a hatch used tape for a hinge to gain access. I had to extend the servo wires to reach the rx behind the spar.

Engine nacelles were next. The black foam board doesn't roll well so I used white dollar tree foam for this piece. Also finished up the motor mount and slot.

Next I started mocking up the front nose section. Again, I went with a flat section and built up the shapes from there. The nose section slides in flush to the spars for strength. Then the skins tie it all together. At this stage I flew the maiden and it was great. 3s on a 9x6 APC prop. It flew excellent, loops, rolls, and inverted. It was very loud though. Naturally the motor mount did not survive the landing.

I added a canopy and engine cones and then started working on the landing gear and paint.

Yellow tips and white bottom for orientation.

Here is my nose wheel set up. The servo horn allows for everything to rotate so it doesn't bind.

This test flight ended in failure, the plane had gained weight and lost thrush with a 7x6 prop and 4s. Perfect opportunity to fix the cramped nose interior.

Built a new nose. A little extra long so I could trim it back just right.

A new low profile nose wheel also helped with the nose shape.

Ready to test again. This time with an 8x6 prop, 4s pack and lots of landing gear height.

The plane flew awesome. Touch and goes were no problem, ground taxi was good, and could still fly loops, rolls and inverted Was a lot of fun to fly and had great presence in the air. It was still very loud and that's ok.

Last step was to finish the livery.

Here are the balsa plans I used to start off from.