Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Edwin-0]

Regarding the VT, is it beter to use à gyro wen flying whit VT? Is it flying bether?

[Evan D]

TVs should not add to your need for a gyro. If you need a gyro, or want one without then add it.

[xviper]

Regarding the VT, is it beter to use à gyro wen flying whit VT? Is it flying bether?

Perhaps if you want to hover it in true 3D style but I don't think the thrust to weight ratio of this very large jet would permit that to happen. You need at least 1.1 to 1 (preferably more) like in the SebArt Mig 29 to achieve a zero airspeed hover. Actually "flying" a plane with VT requires a gyro no more than on a plane without VT. The need for a gyro is purely up to the pilot desire or to resolve some flight characteristic like the tail waggle on the FL OV-10.

[janmb]

Regarding the VT, is it beter to use à gyro wen flying whit VT? Is it flying bether?

If configured correctly, a gyro is pretty much always a plus, VT or not.

VT does not really add to the need though - if you have a non-VT model that is tuned properly and not overly sensitive, it will not become harder to fly once you add VT. VT has a pretty dormant authority in most parts of the flight envelope. You need low speed, lots of thrust, and lots of input for VT to really kick in and overwrite the aerodynamics.

[Jacckall]

How to build this beautiful Mig-29:

https://www.youtube.com/watch?v=UhOxQ2IP1bw

[Evan D]

Darn, click and I get Biden...

[Gringotuerto]

Regarding the VT, is it beter to use à gyro wen flying whit VT? Is it flying bether?

This raises a question of how you would set up gyro on a plane with thrust vectoring. Has anybody done this before, and if so, how? Here some options I can think of, and there are probably others:
1. You can have gyro operate on both TV and on elevator/rudder. Depending on your gyro setup, this might not be easy to do. One was is to mechanically tune the TV to use exactly the same signal as the ele/rudder (same trim, same travel...just Y cable the signal). Another way is to have a gyro function that can operate before a mix.
2. You could have the gyro operate on the ele/rudder, but not on the TV.
3. You could turn off gyro when TV is engaged. This might make sense if you engage TV only to do crazy maneuvers that might not play well with a gyro anyway.

Anyway, the point is, there are multiple ways to set this up. Anybody have experience there?

[xviper]

I have two SebArt Mig 29s. These were the first mass produced "3D" EDFs (made by Freewing for SebArt). One uses one gyro to affect both the control surfaces and the VT nozzles. The other Mig uses two gyros - one for the control surfaces and the other for the VT nozzles. The two Migs are wired slightly differently. Once set up and the gains are optimized, the gyros always stay on, even though I have a switch to turn it OFF. Remember that most gyros stabilize primarily when the sticks are at center. Stick movement supersedes gyro response, hence, the only time the gyro needs to be turned OFF is during the set up and flight testing stage. Gyros are very helpful when hovering and during normal flight, they make maneuvers much more precise and crisp, landings smooth.

[Wrthog]

Have these shipped yet I’m impatient as all heck hahahahhahah

[T-CAT]

I found this just now on FNRC's YouTube.

[Airguardian]

This raises a question of how you would set up gyro on a plane with thrust vectoring. Has anybody done this before, and if so, how?
[...] Anyway, the point is, there are multiple ways to set this up. Anybody have experience there?

I do. Done a lot of flying on thrust vectoring Su-35 and Eurofighter, with and without gyros in different configurations.

1. You can have gyro operate on both TV and on elevator/rudder. Depending on your gyro setup, this might not be easy to do. One was is to mechanically tune the TV to use exactly the same signal as the ele/rudder (same trim, same travel...just Y cable the signal). Another way is to have a gyro function that can operate before a mix.

Not ideal as:
1- This means you can't trim them independently, which is very important for TV jets in my opinion.
2- You will have to apply same gain to VT nozzles and control surfaces which, is far from ideal. You usually want high gain on nozzles and lower gain on control surfaces, and the gain distributes different over the axis for one and the other, so better add two gyros. (Or use one gyro just for nozzles or just for tailerons + rudders).

2. You could have the gyro operate on the ele/rudder, but not on the TV.

This is fine if you only want the gyro to smooth the jet's reaction with respect to wind gusts, and to make flying easier overall, but it doesn't help as much in post-stall maneuvers.

3. You could turn off gyro when TV is engaged. This might make sense if you engage TV only to do crazy maneuvers that might not play well with a gyro anyway.

That doesn't make any sense. The main reason I see to use a gyro on such a jet is precisely to have better control and predictability when executing post-stall maneuvers. If you are turning it off at that point you may just as well skip on the gyro thing entirely.

You didn't list what for me would be the most obvious option that I'd go to by default.
That is, gyro only on the vectoring nozzles.

It's the easier to do as you can detach nozzle control from transmitter trim (so that adjusting trims won't mess up neither your thrustline nor your center-points for the gyro), will mostly feel like it's not there during normal flight as the dynamics of the stabs take over the nozzles but you will notice the jet is much, MUCH easier to control when slowing down, doing high alpha and performing post-stall stunts. Recovery from bad scenarios is much easier too. Of course, you need a bit of throttle so that the nozzles act, if you cut throttle, the plane will fly as if the gyro were off.

Finally, if you really want the extra benefits of both conventional aerodynamic surfaces and vectoring nozzles all stabilized, you can either install two separate 3 axis gyros, or get a high-end gyro that will offer enough separate stabilized outputs to make all channels stabilized.

Here's some footage of my Su-35 and Eurofighter flying with gyro only on the nozzles (EF does have a separate gyro on the canards for a different -scale- reason though):

Hope that helps! :)

[Gringotuerto]

You didn't list what for me would be the most obvious option that I'd go to by default.
That is, gyro only on the vectoring nozzles.

Ah thanks, I have never done TV, this is very helpful. Do you have a switch to enable/disable TV, or you just always have it on? If you are able to turn it on/off, then it would be ideal to have the gyro switch over to ele/rudder when TV is off, but that could be easier said than done.

[Airguardian]

I do have a switch to kill the gyro yes. I maiden my jets unstabilized and get them dialed out as best as I can before engaging the gyro. Once the gyro is proven and works as I intend to, I leave it always on. Will usually power the jet with gyro off, set the plane on the runway and toggle it on just before take-off and killing it off afterwards. Also if for any reason gyro is not working correctly, you can just switch it off. ;)

A single gyro switching from one set of surfaces to another? That's weird and would require quite some custom programming (say arduino board or something like that), I don't see the point.

[sfcfury]

So yea... I succumbed to the peer pressure... I'm waiting on the boat to come in now too.... also ordered a set of the centerburners from Chris aka theRCGeek!

[janmb]

This raises a question of how you would set up gyro on a plane with thrust vectoring. Has anybody done this before, and if so, how? Here some options I can think of, and there are probably others:
1. You can have gyro operate on both TV and on elevator/rudder. Depending on your gyro setup, this might not be easy to do. One was is to mechanically tune the TV to use exactly the same signal as the ele/rudder (same trim, same travel...just Y cable the signal). Another way is to have a gyro function that can operate before a mix.
2. You could have the gyro operate on the ele/rudder, but not on the TV.
3. You could turn off gyro when TV is engaged. This might make sense if you engage TV only to do crazy maneuvers that might not play well with a gyro anyway.

Anyway, the point is, there are multiple ways to set this up. Anybody have experience there?

I prefer having gyro on everything, but that clearly puts fairly high requirements as to which gyro(s) to choose.

For my part, I have used a jeti assist receiver with up to 12 stabilized channels on my eurofighter. 6 stabilized channels for pitch (canards, elevons, both nozzles), 4 channels for roll (elevons and nozzles), and 3 for yaw (rudder, wheel and nozzle yaw). 11 total (yes, 6+4+3 = 11 because of overlap)

For the MiG I will be using two jeti satellite receivers through a Cortex Pro in serial mode, into a Jeti CB200. Will provide 15 stabilized channels with the best gyro in the world.


As Alejandro said, any sort of Y-connection between VT and control surfaces is something I would highly advise against, since it makes it impossible to tune your thrust line and trim surfaces independently - and that is a must, simple as that.

[Airguardian]

11 total (yes, 6+4+3 = 11 because of overlap)

That's quite some Orwellian stuff you have going on ritght there!

[Gringotuerto]

...I'm comfortable showing a bit more "Behind The Scenes" of an Upgrade Option for the MiG-29 which is *NOT INCLUDED IN THE PNP*, but instead is *Sold Separately*. We'll publish pricing, model photos and video, and installation instructions over the coming 3-4 weeks, as we tidy those details...

So it seems like MotionRC is going to both release STL files, but also sell the part? I wonder what material will be used for the "store-bought" version, and if PLA would be strong enough for this. It seems large ABS parts often suffer from a bit of warping. And if PLA is infused with strengthening material (like carbon fiber), it then requires a hardened nozzle (or wears out the nozzle).

[janmb]

So it seems like MotionRC is going to both release STL files, but also sell the part? I wonder what material will be used for the "store-bought" version, and if PLA would be strong enough for this. It seems large ABS parts often suffer from a bit of warping. And if PLA is infused with strengthening material (like carbon fiber), it then requires a hardened nozzle (or wears out the nozzle).

I've been pondering the same.

PLA may very well have the required strength if careful with layer orientation. My main concern would be that any sort of large, sliding contact surface similar to the old nozzles would be very difficult to achieve with FDM printing

[mshagg]

I didnt see anything in Alpha's comments that implied the STL files would be available for home use? That's a fairly mission critical component to have people printing...

[Airguardian]

Nothing of the sort, I asked Alpha about this because I was concerned the ruggedness of a conventional 3D print wouldn't be suitable for the 'gimbal operation' of the nozzle, but he told us they manufacture these with SLA. ;)