Talk:External Cargo Proposal (Slung Load)

From FlightGear wiki
Jump to navigation Jump to search

Related forum discussion

Hi, we did have a few discussions about doing this kind of thing using a little Nasal addon, and several people offered to get involved and contribute various parts to this - but ultimately nobody cared enough to orchestrate the whole effort. For details, see [1]:

Cquote1.png That looks like a lot of fun, I think if we could replicate this in FlightGear, it would be an awesome addon to FlightGear, sort of a challenging gaming element based on real life

I think we should have most ingredients for this ready in FlightGear, i.e. the bo105, support for external loads and -of course- Nasal scripting. I am volunteering to help with the scripting side of things, now we only need guys familiar with FDMs, helicopters and 3D modeling/animations. Any takers ? I think JSBSim has better support than YASim for modeling external loads and external forces, right ?
And this could help convince some of us that flight simulators (and especially helicopters) should not be flown with just a keyboard :P

— Hooray (Thu Dec 12). Re: Seriously skilled heli pilot.
(powered by Instant-Cquotes)
Cquote1.png Yasim has the better payload support + Yasim Choppers are also better as the fuselage is taken into account. I believe JSB chopper FDM's dont do that.

Not sure how you would go about including a payload thats basically flexing and changing position with the relevant forces in ether FDM though.

— StuartC (Thu Dec 12). Re: Seriously skilled heli pilot.
(powered by Instant-Cquotes)
Cquote1.png The payload gets its position updated by an equation of motion computed in Nasal.

It feels its intertia and the gravitational pull, based on last and present position we have a velocity vector on which to operate drag, and the distance between load and helicopter is pushed into a rope force equation - when the rope is tight, it exerts a lot of force propertional to the tension, when it's not then there's no rope force. Oh, and we need to check if it touches the ground of course... Assuming the payload is approximately symmetric that should do the trick - we have frame spacing, so we have a Delta t, we have present and last position, i.e. a Delta x, which combine into a Delta v - that's all we need to solve a discretized equation of motion. It's not actually that complicated

— Thorsten (Thu Dec 12). Re: Seriously skilled heli pilot.
(powered by Instant-Cquotes)


Status - Reinventing the wheel needed?

Hooray, I'm aware of it and this are all nice statements. But I'm not a fan of reinventing the wheel. 2007/08 we had a first serious try to simulate this, and all the stuff is still there. In the last past months I played with it again and now I'm convinced that the used way is still the way to go. Everything we need is already in FlightGear and waits to be used.
It is quite late here and I have to get up early next morning, so my code snippets and proposals, avantages and disadavantages will come probably monday/ tuesday. Please stay tuned.
--HHS (talk) 21:35, 21 September 2014 (UTC)
It will be interesting to see what those issues were - but a scripted/XML (Property rules) approach should be sufficiently flexible to augment or re-implement such a feature without requiring changes to the C++ code, i.e. would be possible to prototype even if you shouldn't find any C++ developers interested/willing to help with this, which I assume is the reason for this write-up. For something like this "to fly" (pun intended!), it will need to be aircraft agnostic, i.e. a lightweight framework that people can easily integrate, and maybe even using on multiplayer. The degree of XML markup/code required on the aircraft side should be minimal and be just declarative. --Hooray (talk) 03:22, 22 September 2014 (UTC)