VTOL fixed-wing UAV

[Ali F]

Ali F
Don't assume a glider is the most efficient configuration. Efficiency depends on what you are trying to achieve.
A modern high performance glider is designed to do one thing really well - to fly as far as possible for a given loss in height. To do this it has to sacrifice strength so it has a very limited payload capacity and restricted manoeuvrability.
Broader shorter wings may be a bit less aerodynamically efficient but structurally are much better so for the same weight as a glider wing it can carry a 'proper' payload and with a bigger area means it flies slower which for a power plane means less power is required.

If you look at a Skywalker in this light it is actually more 'efficient' at what it does than if it had a high performance glider configuration.
There is no simple 'one solution fits all' but just finding the best compromise to met requirements if indeed there is one.

So now, if I can pick a RTF Skywalker, with an FPV and an Autopilot (pixhawk + mission planner) will be great, and after successful flights, I can add sensors and all the measurement instruments, that will be good?

 

[quorneng]

Sounds reasonable but remember a 'good' outcome does depend on the skill and expertise both in setting up the plane and its the electronics.
Just assembling all the bits is no guarantee of instant success. Take it one step at a time.
First get good simply flying the plane to understand its limits and most important fly within the law.

 

[FDS]

You will still need to be able to fly line of sight to safely take off and land as well as to prevent fly away if you have a setting or GPS problem.
Building hardware knowledge incrementally is also beneficial, fully understanding some of this complex stuff takes the average person a lot longer than you might assume just watching videos of flights. If you really understand your gear and it’s capabilities you will get more out of it and have more reliable, successful flights.

 

[evranch]

That's the Skywalker, all right. As Quorneng and FDS say, your first flights should probably be without your Pixhawk until you get it all trimmed up and used to its flight characteristics.

Ardupilot has to be trained to fly it by taking it through banks and climbs (AUTOTUNE mode) and auto takeoff/landing are definitely a weakness of any autopilot system. That's why pilots take off and land our highly automated commercial aircraft. The better you can fly, the better it can fly. I have had Ardupilot do some strange things on sensor failures/bad data, and you always need to be ready to take manual control.

 

[Ali F]

That's the Skywalker, all right. As Quorneng and FDS say, your first flights should probably be without your Pixhawk until you get it all trimmed up and used to its flight characteristics.

Ardupilot has to be trained to fly it by taking it through banks and climbs (AUTOTUNE mode) and auto takeoff/landing are definitely a weakness of any autopilot system. That's why pilots take off and land our highly automated commercial aircraft. The better you can fly, the better it can fly. I have had Ardupilot do some strange things on sensor failures/bad data, and you always need to be ready to take manual control.

You will still need to be able to fly line of sight to safely take off and land as well as to prevent fly away if you have a setting or GPS problem.
Building hardware knowledge incrementally is also beneficial, fully understanding some of this complex stuff takes the average person a lot longer than you might assume just watching videos of flights. If you really understand your gear and it’s capabilities you will get more out of it and have more reliable, successful flights.

Sounds reasonable but remember a 'good' outcome does depend on the skill and expertise both in setting up the plane and its the electronics.
Just assembling all the bits is no guarantee of instant success. Take it one step at a time.
First get good simply flying the plane to understand its limits and most important fly within the law.

Ok guys, now, what do you suggest as an airplane and all its electronic devices?

 

[clolsonus]

Here is my skywalker setup with 2 insect traps for an entomology project:

After this I repurposed the aircraft as a camera ship and slung a 1 lb sony a6000 below the wing right next to the fuselage. I offset the imbalance with weight on the opposite wing tip, but later discovered the weight of the camera package was twisting the wing. Despite a few challenges, I got a *lot* of useful flying and mapping out of that bird. I logged 100 flights on it before I set it aside. It's still in my basement and could be made flight ready at any time.

We were flying with an in-house developed autopilot, but I would recommend grabbing a pixhawk if you want to do autonomous flying. That's probably the easiest and best supported for the average user.

 

[Ali F]

Here is my skywalker setup with 2 insect traps for an entomology project:

View attachment 159234

After this I repurposed the aircraft as a camera ship and slung a 1 lb sony a6000 below the wing right next to the fuselage. I offset the imbalance with weight on the opposite wing tip, but later discovered the weight of the camera package was twisting the wing. Despite a few challenges, I got a *lot* of useful flying and mapping out of that bird.

We were flying with an in-house developed autopilot, but I would recommend grabbing a pixhawk if you want to do autonomous flying. That's probably the easiest and best supported for the average user.

Its really just awesome to see it *__*
GOOD JOB my friend.
So, you propose to go with the pixhawk from the beginning?
Skywalker with a 1 lb sony a6000 and pixhawk + mission planner.
the camera cannot offer an FPV, right?
and for the motor and the propeller?

 

[clolsonus]

Its really just awesome to see it *__*
GOOD JOB my friend.
So, you propose to go with the pixhawk from the beginning?
Skywalker with a 1 lb sony a6000 and pixhawk + mission planner.
the camera cannot offer an FPV, right?
and for the motor and the propeller?

Just to be clear, all I am doing is sharing what I have done as best as I can, and offering my perspective and opinions. I had to do a lot of extra work to get a COTS camera triggering from my autopilot and configured for quality pictures. The a6000 isn't for FPV, but you could easily mount an FPV system on just about any air vehicle of just about any size if you wish. This is something I've never done personally though. I don't have personal experience with the pixhawk, but I think that is a good path if you are just starting out and hoping for successful flights.

For what it's worth, I crashed that skywalker on the first flight ... it went in nose first full throttle due to an autopilot misconfiguration. I intended to fly 100% manually on the first flight so never paid attention to the autopilot config, but by chance bumped the autopilot switch when I hand launched it. The elevator was reversed so it was below it's target altitude (full throttle) but reversed elevator so full nose down. It went in hard before I had a chance to sort out which switch I bumped.

 

[Ali F]

Just to be clear, all I am doing is sharing what I have done as best as I can, and offering my perspective and opinions.

Yes and Im very thankful for all what you shared in this discussion.

I had to do a lot of extra work to get a COTS camera triggering from my autopilot and configured for quality pictures. The a6000 isn't for FPV, but you could easily mount an FPV system on just about any air vehicle of just about any size if you wish. This is something I've never done personally though. I don't have personal experience with the pixhawk, but I think that is a good path if you are just starting out and hoping for successful flights.

For what it's worth, I crashed that skywalker on the first flight ... it went in nose first full throttle due to an autopilot misconfiguration. I intended to fly 100% manually on the first flight so never paid attention to the autopilot config, but by chance bumped the autopilot switch when I hand launched it. The elevator was reversed so it was below it's target altitude (full throttle) but reversed elevator so full nose down. It went in hard before I had a chance to sort out which switch I bumped.

Yes I see.
so, I think Im gonna go for a ARF Skywalker kit, with a pixhawk and spektrum transmitter and receiver + FPV.
I think its a good package for a first plane.

 

[FDS]

You don’t need a Spektrum transmitter, they are expensive vs an OpenTX set up like the Jumper T16 and don’t work with long range radio like TBS Crossfire. You will be limiting your development with most of the mid price Spektrum sets.

 

[evranch]

Seconding the utility of a LRS-compatible transmitter. You really don't want to be failsafing while flying autopiloted mapping missions, throwing an unintended return to launch will mess up your whole flight and your data points.

You can fly with a regular receiver at the start but you want a transmitter with a module bay and compatibility with TBS Crossfire/FrSky R9/Dragonlink for future long range development.

I like my OpenTX transmitter (Taranis but others are available like Jumper) with R9 LRS as its full passthrough telemetry link works nearly out of the box with Ardupilot/Pixhawk.

Using FlightDeck or yappu telemetry software on the transmitter, you can get your full avionics readout on your transmitter screen and avoid carrying a separate laptop for telemetry. Look up FlightDeck and after seeing the screenshots you will want this system

 

[Ali F]

Seconding the utility of a LRS-compatible transmitter. You really don't want to be failsafing while flying autopiloted mapping missions, throwing an unintended return to launch will mess up your whole flight and your data points.

You can fly with a regular receiver at the start but you want a transmitter with a module bay and compatibility with TBS Crossfire/FrSky R9/Dragonlink for future long range development.

I like my OpenTX transmitter (Taranis but others are available like Jumper) with R9 LRS as its full passthrough telemetry link works nearly out of the box with Ardupilot/Pixhawk.

Using FlightDeck or yappu telemetry software on the transmitter, you can get your full avionics readout on your transmitter screen and avoid carrying a separate laptop for telemetry. Look up FlightDeck and after seeing the screenshots you will want this system

You don’t need a Spektrum transmitter, they are expensive vs an OpenTX set up like the Jumper T16 and don’t work with long range radio like TBS Crossfire. You will be limiting your development with most of the mid price Spektrum sets.

Yes I see.
So I think i m going to pick just the airframe of the Skywalker, its about 130$, and pick all the electronic devices separately, this is the right choice??
What do you suggest guys?

 

[FDS]

Usually if there’s a bundled deal with servos, motor, props and some electronics but no receiver, it will be cheaper than fitting out a bare airframe.
You will need to add your choice of camera and autopilot etc but the core systems are best bought with the air frame.

 

[CarolineTyler]

Have a look at http://myflydream.com/products/ their airframes and electronics cover a good deal of your requirements at reasonable prices.

 

[clolsonus]

Buying a nearly ready to fly system is great if that's available, especially when you are just getting started and finding your way into the field. It will definitely save costs and time.

Later though if you start getting more serious and putting expensive cameras or other sensors on board, you might want to consider buying higher quality servos and motor/esc. I've had two hard over servo failures on my skywalker (with the original cheap servos I installed.) One was relatively easy to handle, but the one where the aileron servo failed (and melted) hard over was something where I just barely got it back home with some luck, and could have easily caused a flyaway.

Here is when the elevator servo failed (and melted itself) in the full up position (jump to about 9 youtube minutes into the movie):

I saved it by trying to roll into a 90 degree bank as the aircraft picked up speed after the stall so that energy was applied horizontally not vertically. I kept my turns in the direction that brought me closer to home, and was able to mostly time the last pitch up to plop it right now in the grass <whew!> I don't have video of the flight where the aileron servo failed, but the return home and landing wasn't quite so elegant.

 

[Ali F]

Buying a nearly ready to fly system is great if that's available, especially when you are just getting started and finding your way into the field. It will definitely save costs and time.

Later though if you start getting more serious and putting expensive cameras or other sensors on board, you might want to consider buying higher quality servos and motor/esc. I've had two hard over servo failures on my skywalker (with the original cheap servos I installed.) One was relatively easy to handle, but the one where the aileron servo failed (and melted) hard over was something where I just barely got it back home with some luck, and could have easily caused a flyaway.

Here is when the elevator servo failed (and melted itself) in the full up position (jump to about 9 youtube minutes into the movie):

I saved it by trying to roll into a 90 degree bank as the aircraft picked up speed after the stall so that energy was applied horizontally not vertically. I kept my turns in the direction that brought me closer to home, and was able to mostly time the last pitch up to plop it right now in the grass <whew!> I don't have video of the flight where the aileron servo failed, but the return home and landing wasn't quite so elegant.

Nice save my friend.
What if I make a 3D CAD Model and build it myself (of course using conception machines)

 

[clolsonus]

What if I make a 3D CAD Model and build it myself (of course using conception machines)

My best advice is to point out that if you do everything from scratch, you will have a couple years of work before you get anything to fly reliably. There isn't a right answer or a good or bad approach, but decide where you want to focus your efforts and be realistic about how long things will actually take. If you want to design an airplane, then design an airplane, but make the project about that, and not about all the other things. Just my 2 cents ...

 

[Ali F]

My best advice is to point out that if you do everything from scratch, you will have a couple years of work before you get anything to fly reliably. There isn't a right answer or a good or bad approach, but decide where you want to focus your efforts and be realistic about how long things will actually take. If you want to design an airplane, then design an airplane, but make the project about that, and not about all the other things. Just my 2 cents ...

Ok I understand.
Look at this offer (aliexpress):
PNP for $202.34
ARF for $297.34

 

[Hondo76251]

I've lightly skimmed through the posts here so sorry if I'm repeating too much of what has already been said, but I'll sum up my opinion by saying that trying to learn to build and fly by starting with an autonomous fixed wing VTOL craft is like saying you want to learn fight by trying to box Mayweather. In my opinion it's best to start simple and build on your experience from there. But that's just my $0.02...

 

[Ali F]

I've lightly skimmed through the posts here so sorry if I'm repeating too much of what has already been said, but I'll sum up my opinion by saying that trying to learn to build and fly by starting with an autonomous fixed wing VTOL craft is like saying you want to learn fight by trying to box Mayweather. In my opinion it's best to start simple and build on your experience from there. But that's just my $0.02...

I totally agree with you.
I just want the autopilot option to be in my plane, so I can use it once I can control the plane.