Posted by Old_Pilot |
Nov 22, 2023 @ 09:49 AM | 9,241 Views
I built this to try to confirm the theoretical thrust of this motor/prop combination....3536-1450kV with a Master Airscrew MR 8x4.5 prop. eCalc predicted 78.5 oz of thrust. Measured thrust was 74.5 oz but I was getting some buffeting and probably a few ounces of back pressure because the motor mounting plate is too big (3" square). I'm going to build a new pivot arm with a 2" diameter mounting plate and re-test.
Simple build...all 6mm ply and a 1/4-20 nylon pivot screw. I'll publish the drawings once the design is finalized.
Built a new pivot arm and motor mount.....got 79.8 oz of thrust for about 5 seconds and 78.5 oz for another 10 sec..which is when I need that thrust the most....No buffeting
eCalc tolerances are +/- 10%, so anywhere between 70.65 and 86.4 oz is what they guarantee.....79.8 is a pleasant surprise.
Posted by Old_Pilot |
Nov 16, 2023 @ 05:23 PM | 8,679 Views
Down to push rods and control horns...tomorrow morning....she'll fly Sunday
Posted by Old_Pilot |
Nov 09, 2023 @ 07:14 PM | 8,520 Views
I know I said that I wasn't going to build another swept and tapered wing aircraft, but my flying buddies and my wife almost shamed me into building this thing again. The first one flew great until I lost a servo arm.....broke her all to pieces....anyway, I cut her out yesterday morning and just finished the fuselage and feathers a minute ago....I'm going to cover her in white/orange/black trim. Not going to try to fly a gray aircraft against an overcast sky.....I'll start on the wing tomorrow.
Here's the spec's:
AUW = 37.5 oz, Wing Loading = 37.5 oz / 3.08 sq ft = 12.16 oz/sq ft
Motor: DYS 3536-1450 kV 655 Watts - 279.5 W/lb, 75.5 oz thrust / 37.5 = 2.01 Thrust to Weight
Prop: Master Airscrew MR Series 8x4.5
Servos: Freewing 17 gr metal gear digital
Receiver: AR6210 w/ satellite 6 channel DSMX/DSM2
ESC: 60A Hobbywing with 5V-5A BEC
Airfoil: PW-51
Posted by Old_Pilot |
Nov 05, 2023 @ 06:35 PM | 7,854 Views
While I was waiting on my machine to cut out the "Flying Tiger" foamie for my students, I put my 3D printer to work and extruded some gimble guards or stick savers for my DX 8 and DX 9 transmitters. Here's a pic and I've included the .STL file....They fit the standard Spektrum sticks.
Posted by Old_Pilot |
Nov 02, 2023 @ 06:19 PM | 5,920 Views
My (4) engineering students and I have spent the last month or so coming up with a preliminary design for the STOL DBF Challenge. AIAA has limited us to a 60" wingspan, 30" wide parking width (we're going to pivot the wing), with a cargo of Peg Dolls and crew. The biggest challenge is the maximum take-off roll of 20 ft.....yep, 20 feet. Hence, the articulated rotors. We plan on building (2) aircraft; a foamie to test all the theories, and a standard built-up for the competition. I've taken their design and picked out all the pieces to be cut on my CNC machine. (Due to liability issues, I'll have to cut the airframe).
Construction to start next week with a planned maiden 2 weeks later
Here's what they came up with:
Posted by Old_Pilot |
Oct 21, 2023 @ 12:48 PM | 5,936 Views
I know it's not new, but it's new to me.......once you figure out that there are two backing strips, it's a snap to apply. I got the generic stuff on Amazon.
https://www.amazon.com/Transparent-A...%2C107&sr=8-15
And here's a pic.
Posted by Old_Pilot |
Oct 15, 2023 @ 08:49 AM | 10,860 Views
Been a while since I posted because I'm recovering from cataract surgery on my left eye. Surgery on the right eye will be this Thursday. Can't really make any dust in the shop until November, but I can play with my 3D printer. The engineering students I'm mentoring for the AIAA DBF challenge think that the motors need to articulate because of the 20 ft max take-off roll, but it can't be VTOL. They came up with this......and I wanted to see if I could still solve a 3-bar linkage problem (90 deg travel at the servo - 45 deg travel at the firewall pivot). The biggest challenge is trying to adapt standard components to a custom assembly. But the concept works. The nacelle is a bit clunky and it's heavy, but those problems are easily addressed.
Posted by Old_Pilot |
Sep 27, 2023 @ 02:02 PM | 11,621 Views
I'm excited ! One of the professors at The University of Memphis' Mechanical Engineering Department has asked me to mentor (4) of his kids for the Fall and Spring semesters while they compete in the AIAA Design, Build, and Fly Competition. This year's fly-off will be held in Wichita KS sometime in the middle of April.
The DBF aircraft must satisfy (3) mission profiles that were determined by Cessna, Raytheon, and AIAA......should be interesting. Stay Tuned !
Posted by Old_Pilot |
Sep 20, 2023 @ 07:08 AM | 11,767 Views
Got all the banjo work done yesterday afternoon.....hopefully she'll fly this weekend
Final configuration:
AUW = 37.5 oz, Wing Loading = 37.5 oz / 3.08 sq ft = 12.16 oz/sq ft
Motor: DYS 3536-1450 kV 655 Watts - 279.5 W/lb, 75.5 oz thrust / 37.5 = 2.01 Thrust to Weight
Prop: Master Airscrew MR Series 8x4.5
Servos: Freewing 17 gr metal gear digital
Receiver: AR6210 w/ satellite 6 channel DSMX/DSM2
ESC: 60A Hobbywing with 5V-5A BEC
Posted by Old_Pilot |
Sep 15, 2023 @ 01:38 PM | 11,718 Views
Here's a link to the detailed build log over on Balsa Builders:
https://www.rcgroups.com/forums/show...uite-Build-Log
Posted by Old_Pilot |
Sep 10, 2023 @ 01:11 PM | 12,195 Views
I couldn't be more pleased.....easy launch, lots and lots of power, and she'll glide dead stick like a cub...The chase video was shot using a racing drone with a top speed of ~ 60 mph....I kept the Not Quite at ~ half throttle except for the entrance to the cuban 8 and once just to run off and leave the chase drone. Consensus is she's an 80+ mph hotliner.....probably not up to pylon racing standards, but she's quick, easy to fly, and no bad habits....
Posted by Old_Pilot |
Sep 08, 2023 @ 12:59 PM | 11,527 Views
Just finished this thing except for control horns and push rods.....that's for tomorrow....Video when she flies, hopefully Sunday
Change of plans - she's flight ready - AUW is 38 oz - 12.32 oz/sq ft wing loading...she outta slow down for landing...I'll find out tomorrow.
Posted by Old_Pilot |
Sep 06, 2023 @ 11:47 AM | 12,945 Views
Finished the wings, hinged all the flight surfaces (sewn), but I've made a couple of changes. Trailing edge is now 5/16" (up from 1/4") and the ailerons are 5/16" x 1 1/4" (up from1/4" x 1"). I've also "juiced" the motor and prop to a 3536 1450kV (up from a 2836 1400kV) so I could use that Master Airscrew 8 x 4.5 MR series prop. The little motor wouldn't swing it..well, it would but only for about 30 seconds before I let the smoke out. 48" WS x 9 1/4" (444 sq in) PW-75 airfoil, 1/8" fuselage, 1/8" ply formers, 3/16" feathers. Servos are Freewing 17 gram metal gear digital, AR6210 receiver with satellite, T/E/A conrol. color scheme is going to be yellow wings and feathers with an insignia blue fuselage and a red and white stripe tail flash....kinda sorta like a PT-19. Cowling will be black with a yellow 2" spinner. Speaking of which, the other reason I've gone to a bigger motor is because that little Sunnysky motor's prop adapter isn't long enough to accommodate a spinner back plate/prop/nut.
Hope y'all like it
Posted by Old_Pilot |
Sep 04, 2023 @ 11:03 AM | 13,501 Views
Well, I learned one thing......no more little servos on fast airplanes......she was flying fine, I rolled her up on edge and pulled on the elevator to turn.....and then I had no elevator response at all..I wonder why......See Pic
Of note....The main wing spar didn't break, but that flimsyass servo arm did. The servo has enough torque, but the arm wasn't strong enough.
I'm going to build her again and take what I learned from Bullit I to build Bullit II
Posted by Old_Pilot |
Sep 03, 2023 @ 11:55 AM | 12,910 Views
Here's a short video of the Bullit....The prop (7x3) wanted to either stall or flutter or both at full throttle, so that needs to change. I have plans for that. Also I'm not sure why there's some out of focus spots in the video.....have to figure that out.....but she's quick, even at half throttle, and she'll slow down nicely to land. No bad habits at all.
Enjoy
Posted by Old_Pilot |
Sep 02, 2023 @ 03:16 PM | 10,058 Views
Spent all day yesterday and most of this afternoon building the left wing. Had a change of plans.....decided to build the wing without dihedral. I'll wait until I join the wing halves to start sanding, but she's coming along nicely. And yes, it's my standard I-section spar, D-boxed, V-boxed, and rib caps. Airfoil is a Peter Wick PW-75. The washout is built into the trailing edge/sheeting/ailerons.
I'll post the right wing here when it's done, sometime early next week.
Posted by Old_Pilot |
Aug 31, 2023 @ 09:00 AM | 12,061 Views
I cut her out yesterday and spent the morning separating the parts and sanding all the fur off the edges. Guess I need to start building ! Same technique as always: I'll build and square the plywood formers and trays (tab-in-slot) and then attach the fuselage sides, top and bottom. Shouldn't take too long.
Haven't decided on a color scheme yet, but I'm leaning towards transparent red for the wings and feathers, and a white fuselage. Black cowling and spinner. We'll see
Posted by Old_Pilot |
Aug 28, 2023 @ 02:59 PM | 14,987 Views
This thing was a piece of cake to design and detail. Should be just as easy to build, a welcome respite from that swept and tapered wing on the Bullit.
Just for grins, I ran a tag matrix search on OZ for similar sized and configured aircraft (
https://outerzone.co.uk/advanced/sea....asp?SpanTo=50 ) and lo' and behold, there's about 50 of them that are similar, but "Not Quite" the same,,,, hence the name.
Here's what I'm going to cut and build from. Probably write the NC code tomorrow
Posted by Old_Pilot |
Aug 28, 2023 @ 07:27 AM | 14,472 Views
As I said before, I'm still in balsa mode, thanks in part to the National Balsa sheet bundle sale and the fact I'll be out of commission this fall with cataract surgery...so I'm going to build as much as I can, while I can.
I call this one "Not Quite"....she's not quite a glider, but she'll fly pretty slow, not quite a sport aerobatic, but one can increase the flight control surfaces, not quite a hotliner, though you can always juice the motor and prop, and she's definitely not hard to build.
Preliminary spec's: 3530-1100 kV motor, 40 A ESC, 8x4.5 MA prop, and 17 gr metal gear digital servos
Posted by Old_Pilot |
Aug 26, 2023 @ 07:15 AM | 13,588 Views
Next on the list is my favorite scratch built EDF...the Einzpfeil....I've probably built over 100 of these things over the years, in all configurations and sizes. My favorite is the 27 with a 12 blade 70mm fan, 3400 kV motor, and a 3D printed nacelle.......
Changed my mind....I'm still in balsa mode....only because I'm going to have cataract surgery soon and I don't know how long I'll be down.