This is a short article previewing my latest design, ""One Sheet No Waste Simple Fold Speed Delta".
The key word is "speed". I have not designed an airplane before where the primary concept was speed so this is new ground for me. I also wanted to stay within the "Single Sheet No Waste" and "Simple Fold" design concepts. Stuck in a rut I am! (and digging my way out).
One of the peolpe who built one of my earlier designs asked if I had any suggestions for using the same motor and getting to as high a speed as possible, possibly even 100 MPH. I thought he would get more speed from the earlier delta design but probably not close to 100 MPH. I started thinking about what would go in that direction.
My thoughts were to stay as similar to the design concepts used in my last article as posssible but modify it for maximim speed. My first thoughts were to make it longer and narrower. I started playing with a sheet of paper simply turning the axis 90 degrees and the mock-up came together within a few minutes.
Here is the plan:
To Print: First left click on the drawing to select it then right click to print.
Here are a few pictures of the completed prototype. The paper mock-up appears in the foreground of the first picture:
You might want to move some of this on top for belly landings.
I do like the clean topsides though.
Juxtiposition fo tail plane and winglet angles.
The motor I used on this is the same as the other builder had used on one of my earlier one sheet designs with good results. It is a Turnigy D2826-6 2200 KV. This is a great motor. It has a great thrust to weight ratio and is reasonable. The maximum pull rating is listed on the manufacturer's spec sheet at 960 g. I have tested mine with a 7060 cut down to 6" and got numbers approaching 900 without topping the battery off.
If the pitch of the prop is 6 then (assuming 100 % efficiency) it travels 1' in two revolutions. The thearetical number of revolutions per minute would be the KV (2200) times the voltage (11.1). That would be 24420 RPM. The travel would be half the RPM in feet since the prop travels 1' in two revolutions. That would be 12210' per minute. Times 60 minutes per hour 732,600' per hour. Divided by 5280' per mile equals 138.75 MPH. I do not know how efficioent propellers are but I would guess at least 60%. (I have seen average figures for full sized aircraft at 50% to 85%. So it vafies pretty widely. I am sure it does in the hobby as well.) 60 % of 138.75 is 83.25 MPH. If the propeller is 75% efficient the speed would be 104 MPH. I know there are a bunch of other factors that affect the actual efficiency and speed but it seems to me that 100MPH might be possible.
Update 3-14-15: Final weight ready to fly 539 g. Anticipated thrust 900 g+
Motor: Turnigy 2826-6 2200 KV; Rated 342 W, 960g thrust
Prop: 7060 Orange cut down to 6" (may change to lower pitch after testing)
Servos: (2) Tower Pro SG90 9g
ESC: Red Brick 30A (may change to 40A after testing)
Radio: FlySky FS-T6
Receiver: Hobby King HKGT2R 3 channel (only 7g - less than $6)
Well, that is it for now. I plan to do a build article within the next two weeks. I am also working on an article modifying the "Simple Fold Delta" to and EDF. I am not sure which will be out first but I hope to have both within two or three weeks.
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Spirng is close. The big thaw is on in Westerrn PA. I hope to be flying soon. Good luck on your flying season.