NickRehm
Member
I felt really terrible stripping the v1 for electronics, but it had to be done, so I did that today and got her all ready for flight! You can see the significant drop in size from v1, mainly to reduce weight and squeeze out some better flight performance. GTOW is about 18oz or ~500 grams. I got all the surfaces trimmed, made some updates to my code, and took it out for a quick flight--no video yet. I was trying out full stabilization in forward flight with a 4x4 setup. My thought was that the motors mounted on the ailerons/flaps would give some crazy maneuverability. Flew like it was on rails, but still felt a little sluggish--I think it was the controller holding it back. So I think the new game plan is augmented controls in forward flight: some degree of deflection purely from radio commands, but with some stabilization mixed in. I also flew a bit nose heavy because battery placement turned out to be tricky with the front lift fan in the way. Maybe I'll try flying way tail heavy with the full stabilization first
Since this one is a little smaller, it needs to takeoff from a small box to get the rear props out of the way of the ground, so landing gear looks to be necessary. Any good methods for a sturdy mounting point on these foamies?
Since this one is a little smaller, it needs to takeoff from a small box to get the rear props out of the way of the ground, so landing gear looks to be necessary. Any good methods for a sturdy mounting point on these foamies?
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JasonK
Participation Award Recipient
RE: attaching landing gear:
Take a look at some of the FT builds were they put in landing gear (FT Scout, P-40). There is a bending shape that they do with the wire, so that it gets a very large area of contact in 2-3 dimensions.
RE: flight controller fighting forward flight:
you probably need to tune your flight controller and set higher max roll/pitch rates. if your in rate mode, your telling the flight controller what rate you want it to roll/yaw/pitch at, so setting the max higher for that will have the flight controller make your do so faster.
Take a look at some of the FT builds were they put in landing gear (FT Scout, P-40). There is a bending shape that they do with the wire, so that it gets a very large area of contact in 2-3 dimensions.
RE: flight controller fighting forward flight:
you probably need to tune your flight controller and set higher max roll/pitch rates. if your in rate mode, your telling the flight controller what rate you want it to roll/yaw/pitch at, so setting the max higher for that will have the flight controller make your do so faster.
NickRehm
Member
Thanks! I'll take a look at that. Just need something to elevate off the ground for the props, so doesn't need to be super sturdy, though I am always scared of it just ripping the foam out.
I was flying rate mode in hover and forward flight with max rates at 160 deg/sec, so yea kinda slow. I like those for hover, so will probably change them only in forward flight mode. Just moved the battery location back behind the front fan. Unfortunately the only reasonable place for it is on top of the wing, so it ruins the looks a bit. With it there, the cg is about an inch behind where I'd like it to be (it was about an inch forward with original battery placement). I'll take it out tomorrow pending weather and hopefully get video with these changes!
I was flying rate mode in hover and forward flight with max rates at 160 deg/sec, so yea kinda slow. I like those for hover, so will probably change them only in forward flight mode. Just moved the battery location back behind the front fan. Unfortunately the only reasonable place for it is on top of the wing, so it ruins the looks a bit. With it there, the cg is about an inch behind where I'd like it to be (it was about an inch forward with original battery placement). I'll take it out tomorrow pending weather and hopefully get video with these changes!
JasonK
Participation Award Recipient
@JasonK - I know there are a number of folks like me, diggin' on that. I know little about FC programming, but If I can help count me in.
@Rcjetflyer2 - that will be amazing. I have an eyeball watching this. Keep at it, you're doing great. The project I am starting I was planning on using a Pot to control the angle of the thrust, and tie it in to the flight modes. something like 15 deg below level, is stabilized flight - similar to a tricopter, and the rest just normal flight mode. Likely mixed like a flaperon.
JasonK
Participation Award Recipient
NickRehm
Member
Hey everyone, I've finally released my flight control code and complete documentation that I used for this project. The released code is the generic version, though I do plan on releasing a version with my F-35 mixing along with the plans for the smaller f-35 parkjet. Check out the master thread over on Rcgroups for more info: https://www.rcgroups.com/forums/sho...OL-Teensy-Flight-Controller-and-Stabilization
Github (code and documentation): https://github.com/nickrehm/dRehmFlight
Github (code and documentation): https://github.com/nickrehm/dRehmFlight
the rc project
Well-known member
Hey rcjet flyer, I’m looking at trying this project out(I replied to the thread on rc groups) are you still working on plans? Build log?
the rc project
Well-known member
So I got a bit trigger happy on Amazon and I have the parts to assemble drehm flight coming in the next few weeks, I pretty much have all other components and I’m starting to work on a tricopter testbed. I see a slew of questions from me coming this forums way. Sorry 😬
NickRehm
Member
Yea just dropped what I have on rcgroups: https://www.rcgroups.com/forums/showthread.php?3580135-Profile-F-35-Tricopter/page5
If you need help with dRehmFlight code you can direct questions here: https://www.rcgroups.com/forums/sho...OL-Teensy-Flight-Controller-and-Stabilization
the rc project
Well-known member
SICK! Imu and teensy come tomorrow, still gotta wait a bit for the pins and wire
CampRobber
Active member
I'm building a tiltrotor right now. According to my research the options are:
- big fancy flight controller with Arducopter which has actual tiltrotor support.
- literally any cheap f4 flight controller with inav/betaflight with some odd collection of servo mixes and global variables.
- some vtol/tiltrotor specific system like openaerovtol/kk2/your stuff/etc.
NickRehm
Member
Yep those are your options.
Ardupilot/px4 - Pros are that some VTOL types are already implemented for you, cons are you need to wrestle with their immense architecture to get it working (and figure out how to flash code to your board / figure out which board is supported / have necessary support hardware). You'll also be heavily constrained to the way they handle transition mixing, basically following someone else's instructions to copy their build
betaflight - don't even think about trying weird control mixes...
inav - I actually like inav's control mixer options, not sure if it supports multiple flight modes though so might take some hacking in the code. Not my cup of tea but could be yours
Openaero VTOL - has been the standard VTOL flight controller for years now (NASA used it on their greased lightning VTOL demonstrator LOL), lots of documentation (some would argue too much fluff, not enough basics, disorganized etc...), very dated hardware (kk2 board) that's a pain to flash. I gave up before even trying honestly
dRehmFlight VTOL - a flight controller built like a simple arduino project, modern hardware, requires a little bit of coding basics but no excessive features--just bare minimum. But I'm very biased on this one
CampRobber
Active member
How do they do it and what's wrong about that? Is there a description of your mixing algorithm someplace?
It does. I'm currently using inav on an f411wing and it's hovering in bicopter mode well enough. It supports multiple modes... I'm just not sure how smoothly it will transition between them.
But I'm very biased on this one
Once you get past the brief learning curve of f4 flight controllers, they're actually pretty awesome. And it seems a lot easier to change a dozen lines of inav and flash a custom firmware to an off the shelf board than to develop a controller from scratch.
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