Low-hanging stability weight for FPV

[Dane]

Low Fuselage for FPV Stability

Notice: Excuse my crudeness, I am not very technical. I apologize in advance if you read it and please don't laugh at me! Just brainstorming stability solutions

Notice 2: I've pretty much scrapped the idea of the secondary weight. But I still like the idea of the lowered fuselage.

The Idea: To lower the fuselage further below the wings, to improve stability, create a nice platform and view for FPV rig. The wings and tail would be attached to the main fuselage with carbon fiber rods, or another material, that wouldn't increase wind-resistance from other directions (Like a crosswind)

Excuse my bad drawings, wacom tablet is broken.

Maybe this will make more sense? Very rough idea.

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Original Post:

Spoiler!

This is really geared mostly towards high altitude FPV and improved stabilization. The idea is simple: A controlled, low-hanging weight to balance out uncontrollable forces (wind, mostly). I know there are some systems out there that make minute auto-adjustments to your ailerons and such to counter any outside forces, but what if we reduced them at the source, instead of after the fact?

I got the idea from home-made steady camera systems which incorporates 1 balance to either side, and a camera mounted on top. A very stable triangle. Like depicted in image 1:

Now with a plane, we already have 2 factors stabilizing either side of the camera, the wings... so where is our third point of stability? The fuselage weight and position. But the fuselage can only extend so low for aerodynamic purposes (maybe I am wrong, I am assuming) So this is essentially, an upside-down homemade steady-cam, with the camera position replaced with a weight, and the camera is placed between the 2 main balances (wings)
Image 2:

Now I think a static weight would only do so much ... You could float around straight, and do some basic rudder movements... but any bank maneuvers would perhaps defeat the purpose of the system. I propose that the system be controlled, such that when it banks, the system would move the secondary weight appropriately.
Image 3:

These movements couldn't be made such that X amount of ailerons = X amount of "secondary balance" shift.. because if that worked... Then you are already such a perfect flier that you wouldn't need this stability. The system would have to be operated with some kind of gyro, which kept the "secondary balance" pointed towards the ground at all times (at least in my head)

But who knows... as stated, I am no engineer, and maybe a static weight WOULD work, since the center mass is being pushed outwards on a bank turn...... and maybe a plane like this with a low-hanging fuselage would work!

It could look really cool, have plenty of space for the fpv to move around, the prop could be in front or behind the wings. It sounds nice.

Things to consider:
1. Top speed in relation to flexability of material used to extend weight below fuselage. Pendulum effect is the last thing you would want.
2. Landing with this junk hanging off the bottom (maybe a retractable system?)
3. Weight of the secondary balance in relation to its distance.

If anything, I hope that this will spark some kind of conversation about stability... whether my idea is useful or not.

Thanks for reading and happy sailing,
-Dane

 

[earthsciteach]

It is not difficult to make an airplane inherently stable. Any decent trainer will be inherently stable, accomplishing this with wing dihedral. Your diagram above includes dihedral. This wing configuration is inherently stable because when the aircraft banks to one side, the low side wing is more parallel to the ground than the high wing as can be seen in your third diagram. In this configuration, the low wing is producing more lift than the high wing and therefore, without aileron or rudder input, will cause the airplane to return to a level roll position. Your idea of the weight swinging toward the low side wing would counter this natural stability.

Your idea is looking at stability from a roll standpoint only. An airplane has two more axes to consider - pitch and yaw. So, using the idea of a stabilizing weight, it would have to be controlled through all three of those axes, compounding complexities. Also, this adds weight to the airplane requiring more power, which, in turn adds more weight to the aircraft.

I'm not saying that your idea doesn't have validity. I've played around with the idea of a shifting mass in a rocket to control fins for stabilization. It always gets stuck somewhere in my brain and I never have quite gotten the idea worked out.

With the availability of flight stabilizing gyros at low cost, I'd go with those over a mechanical system. It would not be difficult to add gyros to a camera gimbal system to really remove the "bouncing around." due to wind, vibrations, etc.

Just my thoughts. Don't take them as discouragement!

 

[Dane]

Just my thoughts. Don't take them as discouragement!

Not at all! In fact I scrapped the idea of moving the weight soon after I posted it! I do however still like the idea of a lowered fuselage, it could make for some interesting looking planes.

The real application for this would be high altitude FPV, or any type of fpv that is subject to persistent or unpredictable winds. I think that if some kind of solution like this could be found to reduce movement, then the addition of a gyro on TOP of that would mean far less micro-maneuvers the gyro would have to perform.

My drawings are terrible of course but the fuselage would be fixed to the wings and tail via minimal surface area. Like carbon fiber rods. This would allow you to lower the fuselage weight downwards, without creating counter-productive wind resistance.

Correct me if I am wrong please!

EDIT: Dropped an edit into my original post. Hopefully we can talk on the lowered fuselage subject now without having to make a new thread! Thanks again for your response.

EDIT 2: Bear with me a bit, gonna change the original post around.