This hot air balloon is available as an add-on from flightsim.to .....

https://flightsim.to/file/4344/hot-air-balloon

The creator freely admits that it flies like an aeroplane, and he suggests modifying the flight_model.cfg file to make it behave more like a hot air balloon.

I could make a few educated guesses myself about what needs to be changed, but I thought it might be worth throwing this open to suggestions since there must be many people here who have far more relevant knowledge than I have, (My degree is in physics, but I don't know how to relate that knowledge to the parameters in the CFG file.) I suppose the obvious thing to change for starters would be the cruise speed etc - maybe down to about 10 to make it more realistic - but something similar could be achieved by simply reducing the sim rate, so that's pretty basic! The next thing might be to make sure that the balloon aways remains vertical - ie doesn't pitch or roll. (Yaw doesn't matter so much, and might even be realsitic.) But obviously the thing I really want to happen is for the balloon to rise vertically and be carried by the wind. Ideally then the "engine" would be the burner. When the throttle/burner was applied there would be a lot of lift for very little (preferably zero) horizontal speed. Also my feeling is that there ought to be a lot of horizontal drag so that wind has a big influence on the horizonatal speed. I think the vertical drag would also have to be large so that the balloon didn't drop like a stone. I appreciate that all of this would a lot easier if you were starting with a helicopter CFG, but I'm not sure I can find one for MSFS.

Any thoughts?

airforceproud95 will be very happy about this

I kinda thought about it myself but then went on another project. My guess was maybe reduce to the weight to where just the wind could move you. Then possibly add a prop parameter that would point upwards. Reduce every pitch, roll, yaw input to basically zero. 

Havent got the time to experiment, too busy on the Beaver. But maybe someone else will figure it out. 

Edited December 7, 20205 yr by leprechaunlive

1 hour ago, leprechaunlive said:

I kinda thought about it myself but then went on another project. My guess was maybe reduce to the weight to where just the wind could move you. Then possibly add a prop parameter that would point upwards. Reduce every pitch, roll, yaw input to basically zero. 

Havent got the time to experiment, too busy on the Beaver. But maybe someone else will figure it out. 

Yes - I was thinking about the weight too - effectively making it like a piece of thisteldown. I guess I should just do a bit of trial and error and see what happens.

This would be a great use of of some simple WASM modules to track the temperature/density of the air in the balloon, heat loss, burner on time/heat input, and to look at the effective wind and buoyancy and apply forces/accelerations accordingly.

Personally that's the approach I would take vs trying to do it with a .cfg file.

This would also be a great example of a "custom flight model" where all of the math to determine the rigid body accelerations on the balloon would be done outside of the MSFS flight model.

Edited December 7, 20205 yr by marsman2020

2 hours ago, marsman2020 said:

This would be a great use of of some simple WASM modules to track the temperature/density of the air in the balloon, heat loss, burner on time/heat input, and to look at the effective wind and buoyancy and apply forces/accelerations accordingly.

Personally that's the approach I would take vs trying to do it with a .cfg file.

This would also be a great example of a "custom flight model" where all of the math to determine the rigid body accelerations on the balloon would be done outside of the MSFS flight model.

Sounds good - but probably something beyond my capabilities unfortunately. Maybe others reading this may take up the challenge.