Not much space if you're going on holiday with the family in a Renault Clio. This design fits into a 52cm toolbox with transmitter and all accessories.
Just thought I'll share my crash resistant design that has evolved through many drops and repairs. On impact it is now usually just a matter of replacing a rivet or a prop. The electronics and battery can quickly be removed for installation on another airframe.
The props are 15" RC timers and as shown I get about 23min flight time with a slightly damaged 5000mAh 4cell Lipo at 1500m above sea level, 25 deg C.
The difference in spacing between front and rear props doesn't have a noticable effect on stability and it flies waypoints very well.
I'll post basic plans if anyone is interested or if you want an airframe let me know.
Update: Plans for the airframe
Comments
Is it flying with the CG in the new position? I see you also changed the curved slots. Are you planning some kind of quick release? Interesting engine mounts - my guess is they'll help reduce vertical vibrations, but most vibrations are in the horizontal plane and you lose efficiency if your props are too close to the motor arms.
Here another one with the same plate design. An older KK flight controller as used, so is was placed ontop of the fuselage. 15x15mm booms were used, making it a bit heavier: 1002g without battery; 1420g AUW with a 3S 5000mAH battery.
After drawing it out I see what you mean. Its funny how the circle center and the X center were two wrong extremes. The true CG is roughly in between those.
no, you need to draw lines between the front two motors and back two motors and look at the half way point between the two lines.
Oh I get it now. You basically have to place the FC as if its an X-frame. Basically drawing diagonal lines from the motors to find the intersecting point.
What a great design! Any thoughts on adding spring plungers and modifying the design to accept them for rapid deployment of the arms? Here's an example of what I'm thinking of using, or something similar: Spring Plunger at McMaster
Unfortunately, I can't find a weight specified for these, but other than that, I think it should work with a little modification like replacing the slot cut in the lower plate with two holes at each end of travel, and possibly a spacer just outside the arm's swingpath to help rigidity since the clamping action from the previous locking method is lost, and I guess I have to figure out a way to secure it in the arm... to the CAD machine! This is one of the reasons I love this site: a bunch of really talented people contributing their thoughts, designs, and results. Thanks for the inspiration!
I can confirm Murray's statement there. The CF needs to be on the center of lift.
@Murray and @Jeff: maybe you are correct about the CG. I balanced it on a bottle without the battery (see the picture with the NON-alcoholic bottle); it is almost exactly in the middle of the flight controller. Weight without battery is 936g so it is not too heavy. When I have the battery on I positioned it so the CG did not change. Measured from the yellow nosepiece the CG is at between 12 and 13cm (see picture with folding rule). If a circle is drawn through all motors the midpoint is at about 14cm (see draft in previous post, this position was shown).
Is this what you meant that my CG is off; does it make so much difference if the “propulsion midpoint” and the mass midpoint are off 1,5cm of quad this size?
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