Official Freewing B-2 Spirit Bomber 86" Twin 70mm EDF Jet

[Evan D]

Excellent post, I agree 100%!

The smoothness of the air has a lot to do with how much, if any, control action / slight wiggles will occur as well as altitude.

In calm air without turbulence regardless of speed….she’s rock solid and plenty fast at max throttle.

Bring her by low and fast or even moderately fast when the air is rough and you will see the control action and perceive slight wiggles.

Do the same pass again up high, and you can barely see the action.

Hit a BIG turbulent bump, she may jump as she fights it!

It’s all in what one wants to see and in what air conditions one wants to fly in and how fast.

if the slight (and it is slight) wiggle bothers you, then fly in calm/smooth air. Or spend the time experimenting with the gyro / control box set ups.

To each his own. Tweak away! Part of the challenges of the hobby that some like to do.

IMHO, she’s fine stock, and I accept the slight wiggles when flying in bumpy air or windy conditions. I have elected to NOT mess with the setup. My other birds wiggle too in windy and rough conditions. Said another way and after making many, many B-2 flights, I don’t perceive that there is a design/setup issue. She’s good!

I’m simply glad I have a B-2 that is well designed, and flies well to have fun with and enjoy watching fly by.

-GG

[GliderGuy]

The smoothness of the air has a lot to do with how much, if any, control action / slight wiggles will occur as well as altitude.

In calm air without turbulence regardless of speed….she’s rock solid and plenty fast at max throttle.

Bring her by low and fast or even moderately fast when the air is rough and you will see the control action and perceive slight wiggles.

Do the same pass again up high, and you can barely see the action.

Hit a BIG turbulent bump, she may jump as she fights it!

It’s all in what one wants to see and in what air conditions one wants to fly in and how fast.

if the slight (and it is slight) wiggle bothers you, then fly in calm/smooth air. Or spend the time experimenting with the gyro / control box set ups.

To each his own. Tweak away! Part of the challenges of the hobby that some like to do.

IMHO, she’s fine stock, and I accept the slight wiggles when flying in bumpy air or windy conditions. I have elected to NOT mess with the setup. My other birds wiggle too in windy and rough conditions. Said another way and after making many, many B-2 flights, I don’t perceive that there is a design/setup issue. She’s good!

I’m simply glad I have a B-2 that is well designed, and flies well to have fun with and enjoy watching fly by.

-GG

[Aros]

Regardless of nomenclature or semantics, it seems like at top speeds there is a shudder - gyro induced or not - that has been reported. Not that I proclaim to have the answer but just as a comment I would simply say this is not a model meant to be flown like a F-18 or any other fighter. This is a model meant to be flown scale-like...Half speed, 3/4 speed tops...Just enjoy her for what she is meant to be. (Not pointing fingers, simply a statement from what I have read and seen so far).

[kallend]

Higher speeds the aircraft is oscillating. The gains are maybe a bit high. Some one took out 50% and in the video the aircraft flies pretty good.

That is not flutter. Flutter is an aeroelastic instability, not a gyro induced oscillation.

It really helps to use the correct nomenclature.

[mshagg]

There are gyro oscillations in some scenarios which are obvious in the videos where that is ocurring. I've bumped the roll gains down 10% as a starting point and increased stick priority (changing gain drop curve to 'sport') but also have remote gain on a dial. Also bumped yaw gains down to 85% (from default 100%).

The pitch axis gain is so low that it is effectively an unstablised axis. It will be interesting to see how it responds to any increase.

[MeyerVW]

Higher speeds the aircraft is oscillating. The gains are maybe a bit high. Some one took out 50% and in the video the aircraft flies pretty good.

[GliderGuy]

Has anyone solved the flutter issue? I do have the programming card as well. What all is done?

Do you mean control surfaces moving and working to keep cockpit in front and wheel side down?

There’s no reported flutter issues.

-GG

[Evan D]

Flutter? I haven’t heard that there’s a flutter issue.

[MeyerVW]

Has anyone solved the flutter issue? I do have the programming card as well. What all is done?

[avanti127]

[mshagg]

The E52 has the same servo travel limiting feature, but it is unaware of the mixing board which applies mixes *after* the stabilisation loop. So you'd end up dialling down your throws quite a lot on the individual axis to make sure the combined output didn't exceed the mechanical limit which arises from shortening the drag rudder control rods.

I think the best solution would be replacing the gyro and mixing board with your own, and then replicating the mixing in the transmitter. That way you could set a total travel limit for the servo which is aware of the mixing. Or you could leave it as it comes from the factory...

[Evan D]

Assuming that is the 130% setting in the E52...

p37 of the A3S3 manual (Servo setup) describes how to set servo travel limits on that gyro with its programming card.
https://www.manualslib.com/manual/13...page=37#manual

Maybe this can be done with the E52 as well; the "Servo settings" section of the E52 manual (p10) is not at all helpful.
https://cdn.shopify.com/s/files/1/10...ion_Manual.pdf

[kallend]

While it may be rare it will happen, you also have to consider that the extremely high gain on roll and yaw will be adding in more movement even if the pilot poesn't knowingly do it.

p37 of the A3S3 manual (Servo setup) describes how to set servo travel limits on that gyro with its programming card.
https://www.manualslib.com/manual/13...page=37#manual

Maybe this can be done with the E52 as well; the "Servo settings" section of the E52 manual (p10) is not at all helpful.

https://cdn.shopify.com/s/files/1/1052/4162/files/E52_Instruction_Manual.pdf

[Evan D]

While it may be rare it will happen, you also have to consider that the extremely high gain on roll and yaw will be adding in more movement even if the pilot poesn't knowingly do it.

Admittedly it's probably rare that you're giving full stick input on both axis, but the gyro has its own authority over the servo... and it just seems like good practice to *not* set a control surface up such that a servo can be over driven like that, even in unlikely scenarios.

[Colorc]

Admittedly it's probably rare that you're giving full stick input on both axis, but the gyro has its own authority over the servo... and it just seems like good practice to *not* set a control surface up such that a servo can be over driven like that, even in unlikely scenarios.

I get what you mean and saw this when settin up the drag rudders. I did the 45 mm open and found that i could completly close the rudder with a nice tight snap of the clamshells with rates set at 70. If i also did full rudder and gave it full aileron, i could see the servo trying to close them even further. I bumped my rate down to 63 on the rudder and that was a good compromise of just barely closing the clamshell (with full rudder and not overdriving the servo as much because when commanding full aileron. I decreased expo 10 points and didnt see any adverse change to the way it flies. I agree the the likely hood you would be doing both full aileron and full rudder commands is not likely for the 95% of us

[GliderGuy]

I finally settled on 50 mm wide as close as I could get without a lot more tweaking. I bet 70 mm wide will be fine.

I did not check for the full rudder + full aileron servo overdrive condition as I don’t plan on doing that control input. But, I see your point.

If you are balanced slightly nose heavy, mix in an additional 4 mm of up on the inner surfaces when in the landing configuration. Helps avoid having to hold back stick in the pattern. From 8 mm inner and 4 mm outer suggested to 12 mm inner + whatever on outer for landing.

Slow her way down on final. Float her in.

-GG

[mshagg]

Are you thinking that FreeWings setup is right and the changes told to us by Motion are wrong to do?

I cant comment with authority because I havent flown it. Hopefully this weekend, and I'm inclined to leave it as is. Out of the box the clamshells close with full ail and rud stick - you can check this yourself. With the recommended/suggested setup that shortens the control rods, the servo would be trying to force the clamshell shut further than it physically can.

The few video setups I've seen set the drag rudders to fully close with rudder stick only and I havent seen anyone then feed in roll input.

Admittedly it's probably rare that you're giving full stick input on both axis, but the gyro has its own authority over the servo... and it just seems like good practice to *not* set a control surface up such that a servo can be over driven like that, even in unlikely scenarios.

[Evan D]

Are you thinking that FreeWings setup is right and the changes told to us by Motion are wrong to do?

With the recommended setup physically shortening the drag rudder control rods, such that the drag rudder fully closes with rudder stick alone, are we not over-driving the servo quite significantly when the roll mix from the aileron channel then tries to move that servo even further?

Out of the box the clamshells close fully with full aileron and rudder (at 65% weight) inputs, but leave a neutral position of 70mm open.

[Hugh Wiedman]

I ordered up:

Two Nose Wheels:
BenchCraft 55mm (2.2") x 15mm Treaded Ultra Lightweight EVA Foam Wheel for 2mm Axle
BCT5016-098

Two Main Wheels:
BenchCraft 64mm (2.5") x 24mm Treaded Ultra Lightweight Rubber PU Wheel for 3.1mm Axle
BCT5016-077

Two Main Wheel Struts:
Freewing Stinger 90 Main Landing Gear Strut
FJ305110811

Two Main Wheel Axles:
Freewing Stinger 90 Main Landing Gear Wheel Axle
FJ305110812

Two Main Strut pins (Just in case):
Freewing Stinger 90 Main Landing Gear Connecting Pin
FJ305110810

I have not dissasembled the main retracts to see what size the main strut pins are....betting they are 5mm. If they are the 90mm Singer struts may need drilling out for 5mm.

Will report back on what parts interchange or need cutting drilling......

Hoping to have good luck as a couple pilots have reported with thier own hacks for Grass Operations (Short nap well manicured grass runway)

TwistedGrin

Gave RudyD54 today at the field my spare Stinger 90 struts and stock 65mm wheels that Icarus the 2nd used in his video but the strut hole was slightly smaller than the B2's connecting pin, so he'll have to enlarge the hole a bit to make them fit. That's probably a better idea than using the Stinger connecting pin as that may give you a little too much play. I'm sure he'll chime in on this to give more details, but's he's fighting to keep the stock wheels and not upset the scale police He has gotten off our grass 4 times now, but needs a slight 5-10 mph headwind to do it, which we had most of the day except every time he got ready to take-off, it died to 0 (never does that for me, I get crosswinds) and he had to wait on the runway until it came up.

[mshagg]

With the recommended setup physically shortening the drag rudder control rods, such that the drag rudder fully closes with rudder stick alone, are we not over-driving the servo quite significantly when the roll mix from the aileron channel then tries to move that servo even further?

Out of the box the clamshells close fully with full aileron and rudder (at 65% weight) inputs, but leave a neutral position of 70mm open.