VL3 - Rotax 915 mod

Microsoft Flight Simulator / JMB Aircraft VL-3 915

splash screen

This project is a realism and conversion mod turning the stock VL-3 912 into the versatile JMB Aircraft VL-3 915 top-of-the-line edition. This sporty composite plane is the fastest Ultra Light side-by-side in the world, able to sustain 370kph / 200kts cruise speeds at FL180 yet requiring only 180m / 590ft of runway.

She’s a sports car with wings, and yours to fly!

The Project

We are a team of like-minded enthusiasts that loved the VL-3 from the beginning and turned it into the best 915 we know how. In doing so we have made extensive modifications - always supported by factory data and pilot feedback - to the engine, propeller, flight model, various systems and flight controls.

The Engine

We have upgraded the default Rotax 912 to the more powerful Rotax 915 iS engine. Fuel injected and turbo charged, it delivers a massive 141HP to an airframe that only weighs 600kg / 1322lbs at MTOW. A superb power to weight ratio that is guaranteed to turn the VL-3 into a pure joy machine!

We have gone through great lengths to simulate every aspect of this powerplant, including oil temperatures, cooling temperatures, pressures, gearbox ratio, RPM ranges, critical altitude, compression ratio and a lot more.

The Propeller

The real VL-3 915 comes with an upgraded propeller, and so does ours. The 3 bladed constant speed and variable pitch 173.8cm / 5.7ft Woodcomp KW-31.

While updating the actual 3D model is currently beyond our project scope (you will still see 2 blades), the KW-31’s performance is simulated in excruciating detail.

The Flight Model

Many hours have gone into creating the refined flight model as you experience it today. We have carefully analyzed factory data, observed videos, conducted hundreds of test flights and processed feedback from certified pilots (including a real test pilot) in order to give you the most authentic flight experience possible.

You can be assured that cruise speeds and climb rates (at all altitudes), taxiing, takeoff and landing behavior, clean and landing config stall speeds, roll rates, fuel consumption and so much more is closely or exactly matching POH (Pilot Operating Handbook) specifications.

The Cockpit

The G3X has seen a major overhaul. The engine panel has practically been recoded and now accurately covers the gamut of white, green, yellow and red ranges for all engine information.

Since updating the main display itself would affect all other planes with a G3X as well, we made this a seperate (Working Title) project so you can choose to install it. It comes with a fully functional autopilot, wind data, and various helpful alerts (parking brakes, fuel inbalance, overspeed, pitot heat, low voltage, the list goes on).

It is still in alpha status right now, and any bugs are likely already known (no need to report anything at the moment):

For instructions on how to use it, you may watch a demo on a real G3X AP.

The speed steam gauge has been converted to knots in order to align with data presented in the G3X.

The Liveries

Our project includes an ever-growing and diverse collection of liveries, contributed by various team members. Surely there is something to suit your taste!
All our liveries are updated with authentic VL-3 915 performance placards inside the cockpit.

  • Our current liveries


Download and Installation

1. Download the Mod

Choose from one of these two:

  • Download the Latest Release (fully tested and verified before publication)

*** Update December 2021 - also try the flightism.to link if Github is inop: VL-3 915 Rotax (Improvement Mod) for Microsoft Flight Simulator | MSFS

In addition, we also HIGHLY SUGGEST downloading the Working Title G3X Mod: Working Title G3X - Intro for improvements to the G3X Touch, including Autopilot integration!

2. Locate the Community Folder

On your computer, search for the Community folder of Flight Simulator 2020. The location of this folder depends on whether you have installed it from the Windows Store, Steam and also if you have changed the folder where the packages are located.

  • If you changed the location of packages, it’s the simplest because you should find a Community sub folder in it.
  • For Steam, it should be located in C:\Users\[Computer Name]\AppData\Local\Packages\Microsoft.FlightDashboard_8wekyb3d8bbwe\LocalCache\Packages\Community
  • For Windows Store C:\Users\[Computer Name]\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Community

To access the AppData\Local folder directly, type %appdata% in the Windows search bar to open the folder quickly, then navigate back to Local .

3. Extract and Install the Mod

  1. Delete an older version of the mod if you have it
  2. Extract the downloaded ZIP file
  3. Drag the folder named community-vl3rotax915 directly into the Community folder

If you are not sure how to Extract / Unzip a ZIP file, download and install 7-Zip, copy/paste the zip file to the community folder, right click on it and select “7-Zip => Extract Here” then delete the zip file.


The Team

  • ryanbatc for starting it all and the first Rotax 914 engine mod
  • GotGravel flight model and several liveries
  • CodenameJack447 for multiple improvements to the mod
  • TalonHawk several liveries and various modifications on the model & G3X
  • Garfield for multiple improvements on the mod
  • kaosfere for extensive G3X modifications
  • PongRaider for multiple improvements on the mod

Special Thanks


No-one here is affiliated with Rotax or JMB Aircraft. This mod is purely the work by passionate fans of Microsoft Flight Simulator and the VL-3 915.


Yes, you’r right, the VL3 is slow.
i reduced the drag to 0.68 in flight_model.cfg file
parasite_drag_scalar = 0.68

I don’t think many of the planes released were properly tested and developed to real world specs. Maybe the 152. As always the zendesk report seems to be the best way to share your findings. However I’m sure they know about it and just haven’t gotten around to fixing it. Probably won’t for a while.

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Also the MTOW is hundreds of pounds off.

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After doing more research the 915 is turbocharged and fuel injected…might be a stretch to get that working. I’ve settled for the Rotax 914 for now…which I’ve got the TAS pretty close at 11000 ft…169ktas. 167 ktas is book value. I’ve also setup basic controls for autopilot and changing the CDI source, so I can have a simple 2 axis AP while I’m flying. It’s definitely a quick climber on takeoff (those values will have to be tweaked - it’s got a lancair legacy climb rate at the moment haha). Book is 1600 fpm but I’m almost double that… tradeoff for cruise speed accuracy.

Let me know if you’re interested in numbers… I’m trying to figure out how to make the files work in the Community folder but that’s beyond me right now.

Ah yes I noticed that as well. I think the sim has it around 1000ish lbs MTOW. Book value (converted) is 1322lbs.

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Following. I’ve been mainly flying the VL-3 (love this plane) and would love to have a “closer to reality” model =)

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Theres settings in the engines.cfg for injection type (I think) and you can set whether the engine is NA, Turbocharged, or even supercharged.

Can someone help with the Community folder structure?

All I’m doing is modifying two files. engines and flight_model.cfg. I want a simple user install in the community folder.

So I’ve copied the json files and made a folder structure similar to the default. What do I actually need to do to make this work?

EDIT: deleted dropbox link

This is the Rotax 914 - does about 165 KTAS at 11,000 and about the same at 8000 ft. There is some more drag with the gear down so it needs to come up pretty quickly after takeoff. You will be into the yellow arc as I haven’t adjusted the speed tapes yet. Climbout I figure Vx to be around 90 kias…nets you 2500-3000 fpm initially. Otherwise I like a cruise climb at 120 kias. For cruise setting set prop RPM back to 5400.

Also I recommend setting up basic autopilot kb commands… I think “Z” is default engage/disengage. I use A for hold altitude, H for heading, and Ctrl+N for NAV/GPS. X to change CDI source from GPS to VOR1. I also program buttons on my joystick for changing the HDG and OBS. Ctrl+Home/End will change VS as well.

The community folder structure should match the Official one.

I did this and just added the two edited files. I did see VL3 as an option but with no livery and then in sim when it loaded there was no model etc. So I must have screwed something up.

If you touch the HSI, you should get an onscreen menu to select bearing pointer functions.

I think the autopilot itself is supposed to be controlled from the touchscreen, but we’re missing that page so keystroke assignments are necessary for the modes and settings.

I love the VL-3, but yes, it`s very slow. Maybe it comes the better Rotex 915? And another painting?

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Ok I’ve now done a better mod (using the preferred Community install method).

Install: Extract the zip to your Community folder: https://www.dropbox.com/s/pa4m38ks0ytwpnr/ryanbatc-VL3rotax914.zip?dl=0

Cruise speed at 11,000 ft approx 165 ktas (book says 167) PER Rotax 914 engine
Drag when landing gear extended increased.
Airspeed tape on G3X yellow arc set higher

Known Issues:

  1. The analogue ASI in KM/H will not be the same…disregard that one. I’d probably have to modify the artwork which wouldn’t be impossible…but not at this time.

  2. Plane leaps off ground if you apply too much back-pressure. I try to gently rotate around 40-45 kias depending on weight.

  3. Landing gear extended introduces a lot of drag - bring it up on departure as soon as practicable.

One more note: I can’t guarantee it will be done, but Rob Young (of old Realair) told me he may be able to do the Rotax 915 - it’s fuel injected and turbocharged. That engine will do 199 KTAS at FL180.


Hey thanks a lot for your work. I hope Rob Young will make the 915 as soon as possible :slight_smile:

My community folder (STEAM Version) is here: C:\Users(name)\AppData\Roaming\Microsoft Flight Simulator\Packages\Community

But it works great with your mod! Great work… thanks a lot!

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After a few research on internet I have found that the model we have in FS2020 is the VL-3B which has a maximal IAS of 210 km/h (113 knots) which fits perfectly with what I’m getting in FS2020.

I was able to push it to 120 KIAS at 5500 RPM and it gave me exactly the 130 KTAS in the airplane details given in game.

This is the detailed flight manual of the model : http://www.vliegclubmoorsele.be/docs/VL3/POH-VL-3B-3%20sn%20VL-3-71.pdf

The airspeed indicator marking also fit with what we have in game + the MTOW (1042 lbs / 472 kg from the manual flight).

We got ourself a 2010 plane instead of the brand new ones :stuck_out_tongue:

VL-3B is fixed landing gear, so it’s not what we have. The retractable landing gear versions are different models.

The performance we’re seeing in the sim is about on-par with it, though.


Which is why I modded the engine. I know that plane isn’t a a lancair but I can’t figure out why they made the smallest engine verison. There’s too many UL LSAs in this sim. I want to fast!


Good point I missed that one !

The Rotax 915 and the silver, orange, black paint is great.