Solved FTFC20 Classic to Modern Forum Challenge!

[Vimana89]

Change or add an additional entry? This one looks cool and should go pretty quick!

Change please. If I revisit the bipe at a later date I'll let you know, but doubt it, because I have flown a lot of RET and want to get more into learning ailerons. I chose this one to start because it's a quick but cool build to learn KFM airfoils and AET. I'll take on a tougher AET build at a later time if this goes well.

 

[TooJung2Die]

If possible, I'd like to change my second entry from the Double Decker Biplane to this; the T-Tray

Looking at the way the rudder is curved I'll bet that is a control line airplane design. It will be very interesting to see if that design can be made to fly in a straight line and turn.

 

[hotwax]

hotwax

FB Trixter Beam

https://forum.flitetest.com/index.php?threads/ftfc20-fb-trixter-beam-designed-by-hotwax.60000/

 

[TooJung2Die]

FB Trixter Beam

That's what I call "Classic". Airplanes like that were designed to carry pounds of radio gear and batteries. Built out of foam board with modern RC it will fly even better. Good choice!

 

[Horseman3381]

I have completed version one of the build and initial test flights. See the build log for details

FTFC20 Martian Space Ship designed by Horseman3381

 

[Vimana89]

Awesome to see everyon's progress! The T-Tray prototype went very bad for me. That build is on the back burner now, but will likely take another try some time. Instead of blabbing on here how I'm going to try something else...I tried something else! Still got ailerons though...https://outerzone.co.uk/plan_details.asp?ID=3718. I'll link a pic at my desktop please add All Wing Wonder to my entires! The sloppy prototype flies well but has a few issues with weird stalls if you don't treat her gentle and give enough throttle in banks.

 

[Vimana89]

I have the footage, including a few of the bad stalls and issues happening. I would appreciate any advice and constructive criticism. I have not done much building and flying with ailerons. Most of the planes I fly well are RET. I'm not sure if these stalls and issues are limitations of the design combined with bad piloting habits, or if they are things I can actually address and improve with the build. The problems seem to happen most often when trying to bank at low speed, the more drastic the bank, the worse the stall. I think this double delta is more stable at high speeds and not a great low speed design?

So those more experienced, how much is piloting error and how much can be addressed with the build? This is a sloppy prototype, the 1.0 will have a nose box and through wiring.

Stalls and Issues

Just cruising around

Higher speed(not quite full throttle), more aggressive flying

 

[Vimana89]

I think I'll ask my build and handling question in the newb section. There really needs to be a board for flying and aerodynamics. Here's a link to my All Wing Wonder thread https://forum.flitetest.com/index.php?threads/ftft20-all-wing-wonder-by-vimana89.60028/#post-494258

 

[Morgajus]

I was looking at Peter Tribe's Razorblade. (The original version, circa 1958.) The pdf plans are available on aerofred [https://aerofred.com/details.php?image_id=83569]

The straight-edged, plank, single wing design seems simple enough to convert to DTFB from control-line. Given that I've never designed a plane before, it feels like an appropriate level of challenge. I should be able to hand draw everything because I can't figure out inkscape to save my life and my solidworks subscription won't renew until september 24th.

I'm thinking 30 inch span, folded foam spar, single-ish sheet, whichever power-pack and battery will fit CG-wise (an a or f pack would probably be plenty, but I don't have either yet.) Probably gonna try to fit a 1600 3s so I don't have to buy a smaller battery.
Possibly adding verticle stabilizer/rudder(s) to compensate for the control-line/stability loss and lack of wing sweep/dihedral.

Literally all of my free time to do anything but quick sketches has gone out the window recently, so I'm attempting something new.

All of this being said, before I officially submit an entry, does anyone see any glaring issues with this idea? As stated above, I have ZERO experience designing planes and any helpful advice would be greatly appreciated!

Would elevons be preferable to rudder/elevator for any reason besides what people tradionally see on flying wings? I don't know the science.

 

[TooJung2Die]

All of this being said, before I officially submit an entry, does anyone see any glaring issues with this idea? As stated above, I have ZERO experience designing planes and any helpful advice would be greatly appreciated!

Why try to re-invent the wheel? It's a control-line airplane. You should be the first in the Challenge to build an electric motor foam board control line. Use a transmitter to control the motor speed while flying in a circle.

 

[Morgajus]

Why try to re-invent the wheel? It's a control-line airplane. You should be the first in the Challenge to build an electric motor foam board control line. Use a transmitter to control the motor speed while flying in a circle.

Valid point but I, currently, don't want to learn control-line. Also, i think the lines would be heavier than the airframe. Which going 60-100+ mph would be scary for me, but I would imagine a little like casting in fly fishing (throw the line, not the lure). LOL

 

[Vimana89]

The All Wing Wonder and T Tray are kind of touch and go right now if anything, but the Floating Kidney is flying extremely good. It handles smooth for a RET plane, loops easy, glides, and is basically impossible to crash unless you force it into the ground. For how easy it is to build, it delivers big. Edited flight footage coming soon!

 

[SlingShot]

Valid point but I, currently, don't want to learn control-line. Also, i think the lines would be heavier than the airframe. Which going 60-100+ mph would be scary for me, but I would imagine a little like casting in fly fishing (throw the line, not the lure). LOL

I have flown control-line. I flew as little as an .09 engine with steel lines. No problem whatsoever. The weight of the line was never an issue. The line does create drag as it goes through the air, but that's ok.

 

[Morgajus]

I have flown control-line. I flew as little as an .09 engine with steel lines. No problem whatsoever. The weight of the line was never an issue. The line does create drag as it goes through the air, but that's ok.

I have many semi-technical questions... but most are frivolous. Here are a few.

What is a .09(litre?) engine approximately equivilent to in electric? How fast did it get going?
How heavy was the plane/rigging?

I imagine you would compensate for the line drag in your "trim" adjustments? Or do you just power through it to maintain the centripetal forces?

So far, the only thing I've flown successfully had a self-leveling (altitude maintaining?) gyro and "newbie-mode." So swinging a motor around at high speeds sounds like a laceration waiting to happen (either to me or a bystander.)
I can't even get my FTcrusier in the air...

 

[SlingShot]

I have many semi-technical questions... but most are frivolous. Here are a few.

What is a .09(litre?) engine approximately equivilent to in electric? How fast did it get going?
How heavy was the plane/rigging?

.09 cubic inches. The rest I don't know. Maybe F pack size?

I imagine you would compensate for the line drag in your "trim" adjustments? Or do you just power through it to maintain the centripetal forces?

There aren't any trim adjustments except that you can adjust your handle for the elevator. The elevator is the only control unless you have a throttle or something really fancy like a scale model.

I have many semi-technical questions... but most are frivolous. Here are a few.

I imagine you would compensate for the line drag in your "trim" adjustments? Or do you just power through it to maintain the centripetal forces?

This is handled by some combination of the following standard control-line features: engine offset, right rudder, the position of the lines coming out of the wingtip (far enough aft to get good leverage or is it forward? have to think about that) and a little weight on the outside wingtip. I believe that some models might use an asymmetric wing as well.

 

[Morgajus]

.09 cubic inches. The rest I don't know. Maybe F pack size?



There aren't any trim adjustments except that you can adjust your handle for the elevator. The elevator is the only control unless you have a throttle or something really fancy like a scale model.



This is handled by some combination of the following standard control-line features: engine offset, right rudder, the position of the lines coming out of the wingtip (far enough aft to get good leverage or is it forward? have to think about that) and a little weight on the outside wingtip. I believe that some models might use an asymmetric wing as well.

.09 cubic inches? That's itty-bitty! What was the wingspan?

I see... that makes sense. They spin ccw around the pilot traditionally, right?

I would also imagine that some things might have changed in the past 60 years as far as the line placement/configuration/rules go. The Razorblade seems to have the anchor point for the lines right on the CG line, so one line on either side about equidistant. But it doesn't have any rudder either so maybe there is some interplay involved that I'm missing.

 

[SlingShot]

.09 cubic inches? That's itty-bitty! What was the wingspan?

I see... that makes sense. They spin ccw around the pilot traditionally, right?

I would also imagine that some things might have changed in the past 60 years as far as the line placement/configuration/rules go. The Razorblade seems to have the anchor point for the lines right on the CG line, so one line on either side about equidistant. But it doesn't have any rudder either so maybe there is some interplay involved that I'm missing.

Dunno on the wingspan. But you can search for some designs to get an idea.

Yup. CCW.

That combat model has engine offset. The plans probably show washers under the forward engine mounting screws. It probably has wingtip weight as well.

Trust me. With a .35 engine, it pulls hard and you have to hold on.

 

[Piotrsko]

.09 Cubic inches piston about the diameter of your pinkie, twice .049 ( picture on my glider over on the pre 2000 section), swings a 7-4 or 7-6 prop at 15,000 rpm makes an amazing 1/2 hp that is totally unuseable except for airplanes. Equivalent to a B electric. Could hang a C for controlled lunacy appropriate to control line. That would make an excellent combat plane (DUH) to go against the bloody series, down side is: which way is up. 30 " span is perfect. There will be 1extra wing rib bay on the left side looking down, (inside of circle) wont make much difference, just loops crooked, controlled by aileron trim. Symmetrical wing, fast and sensitive as needed figure 80 to 100mph. DON'T make me build a toothpick or voodoo, not sure DTFB is strong enough..

 

[TooJung2Die]

So far, the only thing I've flown successfully had a self-leveling (altitude maintaining?) gyro and "newbie-mode." So swinging a motor around at high speeds sounds like a laceration waiting to happen (either to me or a bystander.)
I can't even get my FTcrusier in the air...

A combat airplane is not easy to fly, RC or control line. Combat airplanes are not stable, fly fast, turn extremely fast, and go where they are pointed. Keeping track of the airplane's orientation is always an issue. I built one. It flew great, very exciting, but I was not a good enough pilot to keep it in the air long enough to deplete a battery. I still have the wing.

 

[Morgajus]

A combat airplane is not easy to fly, RC or control line. Combat airplanes are not stable, fly fast, turn extremely fast, and go where they are pointed. Keeping track of the airplane's orientation is always an issue. I built one. It flew great, very exciting, but I was not a good enough pilot to keep it in the air long enough to deplete a battery. I still have the wing.

Thank you for the insight! Sounds like
I might not be able to make the 5 minute flight time requirement then LOL

I'll make adjustments as necessary (read; give the sticks to someone who knows how to fly.)

.09 Cubic inches piston about the diameter of your pinkie, twice .049 ( picture on my glider over on the pre 2000 section), swings a 7-4 or 7-6 prop at 15,000 rpm makes an amazing 1/2 hp that is totally unuseable except for airplanes. Equivalent to a B electric. Could hang a C for controlled lunacy appropriate to control line. That would make an excellent combat plane (DUH) to go against the bloody series, down side is: which way is up. 30 " span is perfect. There will be 1extra wing rib bay on the left side looking down, (inside of circle) wont make much difference, just loops crooked, controlled by aileron trim. Symmetrical wing, fast and sensitive as needed figure 80 to 100mph. DON'T make me build a toothpick or voodoo, not sure DTFB is strong enough..

Thanks, that's a lot of info! Hopefully I understood enough of it.
Is the 1/2 hp not usable because the motor shaft is to small to transmit the torque with any kind of resistance?

You're suggesting a b-pack (2212 1050kv) with a 7040 prop for the "slowest" flight?

I am planning to eliminate any asymmetric features in favor of stability, but the plans didn't look to be offset... EDIT: the motor is offset a little to the outside. But nothing about changing the thrust angle. It just shifts the cg to the right.

By toothpick and voodoo I am assuming you mean the balsa twin-boom control-line combat planes? I tried building a twin-boom flyer previously. It looked terrible, (in my opinion,) I wouldn't do that to you.

I am also leaving space in my sketches for carbon fiber reinforcements at the leading edge and/or spar and planning a way to reinforce the tail segment with skewers since it will probably only be a single layer of DTFB sticking out the back to the elevator.



A futher question: stick to the original design and go bank and yank with ailerons or add vertical(s) and rudder(s), for a 3-channel?
With how short the airframe is I'm afraid a rudder wouldn't have much authority. I've only got about 3 inches sticking out the back of the wing to work with, if my math is correct... maximum of 6" if I just tape on the elevator from scraps.