Engine Swap

[Goofyfish]

I am toying around with swapping an engine into an existing model and would like to get it as accurate as possible. Is there a reference (or references) you all would recommend explaining the config files and how they relate to the "real world"?

Rick

[Brett_Henderson]

I've done more than a few virtual engine swaps. Editing the cfg file is easy and straight-forwad, but getting realistic results are not easy.

Rather than me list a volume of possibilities, just post details about the swap, and I'll try to help.

[ShaneG_old]

On this note, I have a nice C150 I would like to add just a little more kick to without drastically upsetting other performance factors.
Would swapping in the default C172 or C182 do the trick? I'm only looking to boost the cruising speed by 25-30kts. It's currently at around 90, and I would like to  have it at 120 or so.

[Brett_Henderson]

Oh man, Shane..  I mean, you can do anything you like, but that would be quite unrealistic. A 6cyl Lycombing bolted onto a C150 just wouldn't work. The CG would be a mess.

Now, I suppose it would be "kinda" realistic to turbo-charge that little 4cyl for extra HP. That would be do-able on a real one (though getting FAA certification would be impossible).

If you're not familiar with realistic cfg modifications.. just email me the aircraft.cfg, and I'll email back a "modestly" turbo-charged C150, along with a copy of the original aircraft.cfg file for backup.

Just remember that you're TBO will be cut in half..  

[ShaneG_old]

They didn't seem that different really, except for the lines I've posted here, the rest of the engine data in the .cfg was identical. Maybe I want something in between these two then? The one I'm wanting to use is only a 4cyl. also, I figured that would be reasonably realistic, at least within the bounds of do-ability. I think engine swap was the wrong terms to think in, it's more like a cylinder bore job.
Would a 6cyl even fit under the hood of a 150?

This is the engine section of the C150:

[piston_engine]
power_scalar=1.00000
cylinder_displacement=50.00000
compression_ratio=7.0000
number_of_cylinders=4
max_rated_rpm=2750.00000
max_rated_hp=100.00000

And this is from the default FS9 C172

[piston_engine]
power_scalar = 1.0                              //Piston power scalar
cylinder_displacement= 90.0                  

[Brett_Henderson]

Oh Geez.. you're right..

[Brett_Henderson]

Ok.. here's what I'd do:

Swap the key engine elements...

Add 150lbs to both the empy weight, and max weights, but leave the CG alone (pretending that your sandbag is the perfect weight, placed perfectly)...


Increase the prop MOI slightly and and icrease its fixed pitch by a few degrees (this would be the custom prop you'd probably need)(the extra HP would run wild on the light, 150 prop)

Test and tweak

[ShaneG_old]

Sounds good to me. Will do!  [smiley=thumbsup.gif]

[ShaneG_old]

Flies like a dream, and got the little bit of extra speed! Thanks for the help. I think it's even easier to land now also.

[Brett_Henderson]

Excellent !  :)

And what's really neat about it, is taking the time to do it realistically.  8-)

You could have gotten the same results by simply increasing the prop-thrust factor. But what's the point of realistic simming if you do stuff like that.. ?

Heck, you can edit the C172 so that the damage speed is 800knots.. and increase the prop-thrust ridiculously, and have a super-sonic, single-engine prop plane  ::)

[Goofyfish]

[quote]Lastly, edit the paint-job to have "EXPERIMENTAL" posted clearly near both doors..

[Brett_Henderson]

This stuff is a blast, when you take the time to do it realistically.

I'll research more later.. but right off the top of my head, I see that your cylinder displacement is way off.

The '360' and '540' engines have the same cylinder displacement (90)..

Consequently, a 4cyl engine has 360 cubic inches total (4 X 90)

The 6cly engine has 540 cubic inches total (6 X 90)

You've upped the per cylinder displacent to 130.. AND added two cylinders.. What you've got is a mythical

[Goofyfish]

Gotcha on the displacemen and thanks for the link!
The FAA Type Certified Data Sheet for these engines lists them as:

6 cylinder, - horizontally opposed air cooled direct drive,with fuel injection,
tuned induction, downdraft cooling and bottom side exhaust ports."

http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgMakeModel.nsf/0/FFAE5A2BB5506DCC8625747A00650001/$FILE/1E4.pdf


Look forward to your other thoughts and will make some changes when I get home.


Rick


(edit for better link)

[DaveSims]

There is a 150 hp version of the 150/152 in real life.  

[Goofyfish]

So I'm fiddling with the cfg file and reading more about the engine and the 130mm question kept nagging at me.
your explanation of 90x6 = 540 is perfectly reasonable to me. But the data sheet on the AEIO-540 engine is:

"Bore and stroke, in.