Wind simulator fans

That looks nice, @dododge! I can't print in one piece since my print volume is small, but I hope to do something very similar.

I just got out of my trusty Lotus 49 at Monza classic in Project Cars 2. In that setup I can accelerate faster than the fans can ramp up, but it's not noticeable for me unless I'm looking for it. Once again, the quietness of the fans tops the lag. I did hear just a little fan whine but barely. I run with the sim volume down a bit to not wreck my hearing any more than I already have so the higher sim speeds and higher fan speeds did get me to where I could hear the fan noise. But it was just noticeable and not bad.

And fan acceleration isn't that far behind a Lotus 49 at least. How big a deal it is for someone will just depend on how much they look for it I guess. For me I just settled into the rhythm of Monza and enjoyed the ride. Also, the effect is going to be less noticeable at certain tracks. Especially with a rolling start, Daytona will be a total pleasure with only pit stops to annoy the sticklers. But again, the quiet is where these fans shine. I'll trade some lag for that. The quiet is that noticeable.

Also, I got the anemometer. Wind speed at the outlet of the 6" to 4" reducer is about 33 mph and out of the elbow, just a few mm away from the flow straightener is 36.8 mph (slightly smaller diameter). I checked Avenga's video of his flow straighteners and he hits 29 km/hr at what looks like a couple of feet from the air outlet. It's really hard to say if this is accurate or not but about the same distance I get about 35 km/hr. () I get 39 mph at the outlet of the SeaFlo at full speed so the wind speed is actually pretty comparable after necking the TerraBlooms down to 4" but the SeaFlos are also much louder at 65 db about the same distance from the inlet and up around 105 db the same distance away from the outlets but no flow straighteners now. But head to head, the SeaFlo fans are definitely significantly louder with a lot more native fan noise that drowns out a lot of the "wind" noise. Wind speeds seem comparable with a slight edge to SeaFlo.

Lastly, I checked with and without the TerraBloom tail cone and that only makes for an additional 2 mph at full speed. Not a huge difference but it's at least a bit more flow. Those numbers in the comparison were without the tail cone.

And one more difference between these setups is the SeaFlo fans still have the velocity stacks in place and there aren't any yet on the TerraBloom fans. Avenga saw a noticeable difference with his so when I get them onto the TerraBloom fans, numbers may get better but no guarantees. It will be easy to test when I get them in place so will update.

Overall, the quiet is the big in your face difference. Wind speeds seem about the same but may tip to the TerraBloom favor with velocity stacks. Not far to go to get that but the difference will still be slight and probably not noticeable. I really thought I was getting more wind from the TerraBloom fans but it could just be the quiet accentuated the wind? I do not know but I trust the numbers more. I am not bothered by the lag at all and in an airplane don't even notice it. Those doing catapult launches might, though. I can notice it in a car but those not changing their speed by really large amounts really fast are less likely to be bothered with it - I think. That's obviously very much an individual response.

So that's it except for the velocity stacks and if those make a difference. I have no trouble recommending these fans. I'm loving mine.

@dododge - I was looking back through posts and I would bet at least some of the inlet noise in that SRS kit is from the spiders that hold the cone over the motor hub. They are right next to the blades and where wind velocity will be highest. Have you tried one without cone or spiders, or without spiders and the cone double-stick taped or similar to where you reduce inlet turbulence with the cone but not have bars in the airflow? Or are they airfoil shaped to help smooth flow around them?

I did give them a cross-section shape similar to the center cone, though now that I check the part again I can feel a small protruding lip at the bottom because it was printed right on the glass and I tend to get a bit of "elephant foot" on the first layer.

Just based on the sound, though, I suspect it the extra noise was more due to general airflow. As I recall, when just holding the part in place for a quick test I could feel it being pulled toward the back of the fan by the air movement. If/when I get around to the redesign I could try something that moves the spiders farther from the fan and gives them a canoe-like cross section.

Hello, I’m Martijn from the Netherlands and new here. I’ve ordered two terrabloom fans (220v) version to try this out. Could you perhaps explain which other equipment I would need (ideally with links) and which Arduino code you’ve used? Great project, by the way, looking forward to getting it to work!

Hi Martijn, the code I use is in this post: https://www.xsimulator.net/communit...rmoto-and-arduinouno.6876/page-31#post-190754

I use an Arduino Uno to run it. You can find those all over the place. I would guess the knock off versions would work too but can’t guarantee that though.

You also need a level shifter to interface between the Arduino and the fans. The fans are 10V on the control circuit and will fry the Arduino if you don’t use a level shifter.

The level shifter I used is described here: https://www.xsimulator.net/community/threads/wind-simulator-fans.14124/#post-190062

There are lots of level shifters out there. People working with Arduinos and Raspberry Pi’s etc use them a lot so places that sell those should also generally sell level shifters. This one has extra channels and is bidirectional. You don’t need that but it was easy and Adafruit stuff is good quality. Since you’re in the Netherlands, you probably would want to get that somewhere else but use the Adafruit page to make sure you something with the same kind of level shifting capabilities.

The only thing about the Terrabloom fans, as mentioned above, is they don’t speed up as fast as the SaeFlo fans. Not bad, though. Very workable for me but one guy here preferred the responsiveness of the Sea Flo’s. That said, where the TerraBloom fans really shine is in sound levels. They are quieter and that is so nice especially if you have open headphones.

As to longevity, I was going through a set of Sea Flo fans each year. Still on my first set of TerraBlooms. It’s not quite a year yet but they run like the day I got them.

Thanks very much, @Zed, for your reply! Do you also have some information on which things I need to solder? I saw your photo's, which already help, but just to see it in text as well. The plugs from the fan which go in the Arduino case are included with the fans, or do I need to purchase these separately (and where)?

Those plugs are included with the fans stock. You just need to salvage and reuse the jacks in the speed controller (just a potentiometer) boxes.

I can’t tell you how to connect other level shifters, but for the one I used from Adafruit, the A side are the low voltage inputs and the B side are high voltage outputs. You just connect the two PWM outputs from the Arduino to the A side along with 5V and Gnd from the Arduino (LV and GND, respectively, on the level shifter with both on the LV side). The level shifter outputs go to the blue wires in the TerraBloom jacks salvaged from the speed control boxes. Just match them up - if you run PWM outputs to A1 and A2, connect the blue wires to B1 and B2. The black wires from the jacks both go to GND on the HV side. It’s not totally kosher, but I only connected one fan red wire to the HV terminal on the high voltage side. The yellow wires are tachometer outputs from the fans and I just secured those with some hot glue to keep them from ever getting away and shorting against anything. Same for the other unused red wire. You don’t want to connect both red wires as those are both power. Connecting them together could cause unwanted currents to flow if for some reason they both aren’t the exact same voltage.

The reason it’s not quite kosher is each fan should have its own level shifter so each can be referenced to its own fan’s power circuit. But they are both 10V and the speed control circuits are just looking for voltages with a small amount of current. One fan circuit can easily supply both level shifters on one board. You just need both grounds connected so they are referenced the same. The photos should help.

Whatever boards you use for level shifting, they should have a low voltage side (LV) and that’s the Arduino connections. The outputs are on the high voltage side (HV) and are what connects to the TerraBloom speed control circuit. This level shifter is meant for SPI interfacing and is inherently bidirectional. We don’t care about that and are only using it to change a 0-5V PWM square wave into a 0-10V square wave with the same duty cycle. Simpler circuits could do the same thing.

The design would be similar whatever level shifter you use. You can use the data sheets at the Adafruit web site I linked to extrapolate to other level shifters. Those little level-shifting boards using the same parts are all over the place. If you find one using the same BSS138 ICs, it will probably be identical. Just don’t short the 10V lines to ground and the most you should blow is the Arduino if you manage to connect up 10V to one of its outputs.

But that’s the flow. You just need to change a 0-5V square wave into a 0-10V square wave. You could also use optoisolators if you wanted.

The fan speed control circuit is really just looking for a level (you can turn a 0-10V PWM square wave into a variable 0-10V level with a resistor and capacitor). PWM is just really easy to use as a control method and is built into the Arduino. The fan circuit converts the square wave into a level but you can also just feed them a DC voltage and they will behave the same. You could also use a DAC if you wanted to, but PWM is cheap and easy.

First photo is from the Adafruit product page and should get you oriented. The other two should help to explain the connections. Just remember the LV side is Arduino. The HV side is TerraBloom.

@Zed any chance you know how to program wind speed for video recorder creator??

Sorry, I don’t even know what video recorder creator is. If it’s replaying a sequence with heave, surge, sway, etc, I think it might be included automatically due to replaying the other motion cues. Just guessing, though. And that’s strictly a guess. I’m unfamiliar with that.

But if all you need to do is make the wind sim understand different commands from a software package, that should be very doable. Just need to know the command format to have the Arduino understand it.

Hi - new to this; looking to add wind to my racing rig. Seems like the Seaflo blowers aren't the way to go if starting from scratch. Any reason why I shouldn't go with a single larger 8" TerraBloom (ECMF-200) if my plan is to split that into two 4" outputs? I'm assuming the reason @Zed went with dual 6" units is because that was what you had with the bilge blowers

Hey @Zed Do you know of hardware that can accept telemetry data that can control or regulate fan speeds? We can write telemetry data using the VRCI plug in. How we interface that data through sim tools is another question in addition to what hardware can regulate power based on it. You mentions a servo type...?? Can you elaborate. This seems like an awesome option when trying to write our own wind data to be able to play back.

@lbwski - I don’t think it’s a forgone conclusion to not go with standard DC blowers. There is a significant lag in the TerraBloom style blowers since that’s not really a factor in their design application and not needing to change speed fast makes their circuitry cheaper. I think auto racers probably won’t like TerraBloom setups since the lag will get real apparent. Airplanes don’t tend to change speeds near as fast so TerraBlooms can be more appropriate but there is lag. For more faithful simulation of rapid speed changes, the SeaFlo style may be a better choice.

That said, I was also looking to not grow the rig too much longer. I’m also stuck with a relatively small build volume on my printer and 6” was just what I could do. There’s really no reason not to go with another size. It’s whatever works. One larger fan may be a lot cheaper too. (I don’t know pricing but bet.)

@Ola Shaw - The TerraBloom fans take a number of different analog and even digital control signals right out of the box. I used a level-shifted PWM signal from an Arduino to make it interface to SimTools. Servoing the fans wouldn’t be too tough but would take a slightly different control I think so the fan speed could be fed back. But the Arduino control scheme the other guys came up with works great as is. The TerraBlooms just have some lag and then coast. Just like race cars can out accelerate the TerraBlooms, they can also out brake them. That’s where I thought servoing might be handy. Not sure what the best hardware would be for that, though.

@Zed That is awesome for Realtime playback from a joystick or controller but how can you record that output to replay without the controller using game dash and sim tools? We are trying to write programing to our own go pro footage....

@Zed so we can experience first person feeling of go pro capture.

@Ola Shaw - Apologies. I didn’t understand your question. There is a replay mode in SimTools but I’ve never used it and am not familiar with what it can do and how. That might be better asked in the SimTools support forums here. Just a guess but I don’t see any reason wind wouldn’t be included. I don’t know about the GoPro angle, though. You might have to manually create wind values if you can’t somehow derive them from the GoPro (maybe using GPS coordinates?). The dead simple version would be to build a table of fan speeds and play them back but that isn’t very flexible.

The TerraBloom fan adaptation I did is just a modification of what others here did with the SeaFlo fans with the control part being basically identical. Whatever can be done with the “stock” SeaFlo and Arduino setup can be done with the TerraBloom version because of that, but unfortunately I don’t know how to do what you are asking.

@Zed - thanks, that makes sense. I'm going to give it a try and see how it goes. I plan on always running the fan at some baseline level (I need at least some airflow or I get car sick - even in a real car), so maybe the lag won't be as pronounced going from 33%->100% as compared to starting at zero. The noise from the SeaFlo is a concern for me.

@lbwski - I actually put an idle fan speed in my Arduino code so that until it gets valid commands (i.e. a plugin starts sending wind data) it runs just above idle. Not for motion sickness but for comfort since in VR headsets can get warm if there is no wind. As soon as it gets a wind command, though, it can drop to zero when commanded. Pressing reset on the Arduino gives it a no-input idle speed again. Wind is nice. ;-)

Thought I’d post an update since I installed the wind gear this weekend. Working great so far; I feel like the single 6” split into two 4”s puts out a good amount of air.

I use SimHub to drive it. It doesn’t have any flight sim compatible plugins though; I mainly race cars. It does have an option for “static wind” built in, so you can easily set a low baseline speed that’s always running (as discussed above). May need to research software that supports wind and shakers in MSFS.

What about SimTools? The MS FS 2020 Plugin supports Game Dash (for wind) as well as Game Vibe (for shakers).

Thanks, just the box I was looking for. Will be interested to hear if the narrow air outlets work better than the circular shape. I've got mine mounted on top but the thin outlets mounted lower down would have a cleaner look.