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FTCC'18 WWII Vought V-173 "Flying Pancake"

#21
So I did some more research, and the V-173 had exceptional slow speed performance and STOL capabilities. In fact, the Navy was so impressed by it's carrier-based opportunities that it even considered pursuing VTOL capabilities (I guess the ship's speed added enough lift?). But the planes max speed was a mere 138 mph, making it impossible to be used as a fighter unless it's power plant is improved (the XF5U, the upgraded fighter ordered by the Navy, had Pratt and Wittny engines and 4 bladed props).

Scaled down, this plane would be pretty slow (64 mph would be a little fast). Also I read somewhere that it seemed to fly in level flight with a high angle of attack, as if it was in a perpetual high-alpha. I will have to keep these things in mind when testing the prototype. If the plane has too high of a stall speed and can't fly slow enough to look scale, I will change to the symmetrical airfoil.

And I also realized it had elevators in between the vertical stabs and elevons as well, so I will have to add them in to the design (before I only had elevons on the horizontal stabs). :p
 

PsyBorg

Wake up! Time to fly!
#22
I would suspect the elevons were the control surfaces and the pure elevator would double as a flap as well as "Trim" for more level flight but still having full control with the elevons.
 
#23
So I did some more research, and the V-173 had exceptional slow speed performance and STOL capabilities. In fact, the Navy was so impressed by it's carrier-based opportunities that it even considered pursuing VTOL capabilities (I guess the ship's speed added enough lift?). But the planes max speed was a mere 138 mph, making it impossible to be used as a fighter unless it's power plant is improved (the XF5U, the upgraded fighter ordered by the Navy, had Pratt and Wittny engines and 4 bladed props).

Scaled down, this plane would be pretty slow (64 mph would be a little fast). Also I read somewhere that it seemed to fly in level flight with a high angle of attack, as if it was in a perpetual high-alpha. I will have to keep these things in mind when testing the prototype. If the plane has too high of a stall speed and can't fly slow enough to look scale, I will change to the symmetrical airfoil.

And I also realized it had elevators in between the vertical stabs and elevons as well, so I will have to add them in to the design (before I only had elevons on the horizontal stabs). :p
The V-173 reminds me of a twin nutball. I bet you could make yourself a "trainer" while you're working out your final design.
 
#24
I would suspect the elevons were the control surfaces and the pure elevator would double as a flap as well as "Trim" for more level flight but still having full control with the elevons.
Yeah I see what you mean. They would make good flaps! Although, in one of the pictures I saw, I remember seeing them slanted up. Also, one website (Military Factory I think?) described them as elevators.

Erospace said:
The V-173 reminds me of a twin nutball. I bet you could make yourself a "trainer" while you're working out your final design.
You know, that's true. It does share some similar flight characteristics. Thanks for the idea!
 
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#25
Practicing in SketchUp and Taking a Pause

Hello all,

So first: To practice, I created a chuck glider of my own design in my.SketchUp.com (online, browser-based Beta version of SketchUp) based on Jason Anderson's Youtube tutorials. I am very pleased with how it turned out. The glider is easily balanced and uses modeling clay in a "power pod" in the nose to center its CG. I originally planned for it to be a low-wing Mighty Mini Combat plane, but the tail was too small, I forgot to design slots for pushrods and control rods, and there's no room for servos or a battery! :eek:

Also, there is no way to export a 2D graphic in the version of my.SketchUp now available (it's in open beta), so I had to take a screenshot, scale it in Microsoft Publisher, and then print to a PDF. That is why it prints kinda funny...but it still works! ;)

Obviously this is not the "Flying Pancake," but I thought before I start designing that I should get some experience working with Google SketchUp. I still have to add the red to the half-cut lines for the hinges and airfoil, but if it's a chuck glider they're not really needed. I can probably just do that next time in MS Publisher. If anyone would like the plans they can be found below. (Note: .png file not to scale; use .pdf file)

View attachment MightyMiniCombatPlane_PLANS.pdf

MightyMiniCombatPlane_PLAN.PNG

20170728_104226.jpg

20170728_104306.jpg


Second: I still have a major project in the works that has been pushed to the back burners recently. That project being finishing my Dad's Balsa P-40, I really have to devote more time to it. So I am taking a break from this project until I finish the P-40. I should still be able to have enough time to finish designing by the competition deadline. You can check out the P-40 thread here: http://forum.flitetest.com/showthread.php?34678-Build-Log-Building-My-Dad-s-Uncle-s-Guillows-P40

 

rockyboy

Skill Collector
Mentor
#26
I love how that P-40 is turning out too! Just make sure your family knows that you are not available over Thanksgiving break while you finish up your Pancake project :p
 

JimCR120

Got Lobstah?
Site Moderator
#29
David, regretfully I think you slipped by without me getting the pleasure of meeting you face to face, sir. I hope to rectify that in 2018.

Twin Nutball. I think you're on to something. I might have to do a conversion after seeing how the Flying Pancake goes.
 
#30
Designing in SketchUp

So I made enough progress on the P-40 to begin designing the Pancake in Sketchup. I used a reference image and got most of the general geometry except for the engine nacelles. When I reached designing the cockpit I wasn't sure which design to go for. One is a more accurate, "geodesic" style design and the other is a simpler, rounded-top design. The geodesic design will probably be simplified somehow before the plans are finished, but it gives an idea of what it will look like. I am not sure which one is better, so your guys opinions are appreciated.

Geodesic Cockpit Style.PNG

Simple Cockpit Style.PNG
 
#31
So I have thought about it more and I am going to go with the geodesic cockpit, just because it looks nicer. I'll have to simplify it later when I make the plans.

Meanwhile, I have run into another issue. Unfortunately, those massive props don't scale down well to a mighty mini size, which is the only sized power packs I have at the moment. You can see in the attached pictures that the props are not to scale with the rest of the aircraft. I scaled the aircraft to the engine nacelles to fit the mighty mini sized power pod.

Scale Props Issue.PNG

So now it is basically choosing which parts to keep scale and which to "fudge." Should I lose the scale props and keep the engine nacelles the same or make the props to scale and make the engine nacelle larger? Any feedback would be appreciated. :confused:
 

localfiend

I like 3D printers...
Mentor
#33
So now it is basically choosing which parts to keep scale and which to "fudge." Should I lose the scale props and keep the engine nacelles the same or make the props to scale and make the engine nacelle larger? Any feedback would be appreciated. :confused:
I'd bump up the scale of the whole aircraft just a bit so that your nacelles can handle larger motors if someone wants to do that. Or just make the nacelles slightly bigger to give you enough room to bolt o. Something bigger.

The flapjack is sized to work with 2 C pack motors, but will also work with some much larger motors that can swing big props.

These round fuselage wing things have a ton of lifting area, so motor compatibility range will be huge.


How hard would it be to fit a blue wonder on your plane now? Or maybe even some of those short fat low of quadcopter motors that can spin props above 10 inches.
 

localfiend

I like 3D printers...
Mentor
#34
#35
Take a look at those. Most would probably let you run 10" props. Maybe a bit bigger on some with 2 cell batteries. Remember, you're not gonna need a lot of speed to stay in the air, so you can go light on the throttle. The Pancake wasn't a high speed fighter after all.

https://hobbyking.com/en_us/2210n-1000kv-brushless-motor.html

https://hobbyking.com/en_us/ax-2308n-1100kv-brushless-micro-motor.html

https://hobbyking.com/en_us/turnigy-multistar-2209-980kv-14pole-multi-rotor-outrunner.html
Wow localfiend! That's a huge help. And yes, with a max speed of 138 mph in a dive, the Pancake was definitely not designed for high speed performance! ;)

What is the equivalent of these motors in FT Power Packs?
 

rockyboy

Skill Collector
Mentor
#36
Meh! If the design hasn't been shown to fly with an FT power packs, it'll miss a few points on the score. Having props and nacelles closer to scale will add a few points.

I'd say build it cool and how you love it, and if you have a chance to test it and prove it works with a power pack motor too that's all good too. :)
 

localfiend

I like 3D printers...
Mentor
#37
Wow localfiend! That's a huge help. And yes, with a max speed of 138 mph in a dive, the Pancake was definitely not designed for high speed performance! ;)

What is the equivalent of these motors in FT Power Packs?
There is no equivalent for those I listed. They're reasonable lightweight, though slightly bigger than the mighty mini sized motors and lower kv which will allow for a bigger prop.

That's the thing about this plane. The big props were about efficiency and drag reduction by blanketing the whole airframe. For RC, it doesn't much matter. At the size you have it pictured, it would probably fly with any motor flitetest sells. Well, excepting the gremlin motors. But those are new and don't count lol. :cool:
 
#38
There is no equivalent for those I listed. They're reasonable lightweight, though slightly bigger than the mighty mini sized motors and lower kv which will allow for a bigger prop.

That's the thing about this plane. The big props were about efficiency and drag reduction by blanketing the whole airframe. For RC, it doesn't much matter. At the size you have it pictured, it would probably fly with any motor flitetest sells. Well, excepting the gremlin motors. But those are new and don't count lol. :cool:
Ok I see. I just want to make sure that it could still fit on a power pod. That way I can use it for any other planes that I might need it for.

So with the scale issue take away I will go ahead and continue with the design process. Thanks for the help guys!
 
#39
Finished the wing design and scaled up the props to 10 inches for reference. I did design the airfoil to be flat on the bottom just for ease of build. If don't get the kind of performance I would like from the traditional airfoil, I'll redesign and change it to a symmetrical airfoil. Now I just need to make the wing spar and make a BUNCH of tabs and slots to fit everything together. :p

Wing Shape Done!.PNG