Carenado PA28RT (Turbo Mod?)

[iflysioux]

Hi all,

I was wondering if anyone had done a mod on the .cfg or .air file to give this airplane a turbocharger? I'm not complaining about realism at all, as a matter of fact it barely climbs and glides like a refrigerator just like the real thing! But I've always wonder how much better it would do with a blown engine. I'm not really confident in my editing skills to try it myself so I was hoping someone else had done it, though I guess I could just make a separate aircraft folder for the turbo and play with it until it works.

Thanks

[Jim Robinson]

I've done it with the 182RG, there's really not much to it. Like you say, make a copy the PA28 folder so you don't mess up the original. When you do this you'll need to change the title= line of each variant in the acft.cfg as no two installed aircraft can use the same title regardless of which folder they're in (they won't show up in the select aircraft menu if they don't have unique titles). Obviously you'll also need to change ui_variation=White blue & blue sky to something like ui_variation=White blue & blue sky Turbo for each variant as well. With that done it's just a matter of modifying the [piston_engine] section of the acft.cfg as shown below:

[piston_engine]
turbocharged= 0 //change the "0" to "1"
critical_altitude= 0 //this is apparently the altitude that the engine will start loosing power, change it to 12000 or so
max_design_mp=35 //this is already set to "35" on the Arrow, probably OK at that value

I think that's about it, you may want to experiment with the critical altitude and max_design_mp in the sim and set them where you like them. I didn't make any modifications to the .air file, I don't think there's any need to.

Jim

[iflysioux]

Ok cool! That's easier than I thought. I do know that the max MP is 41" so I'll have to find a new gauge since the one installed in the Arrow only goes to 35, but the Saratoga is Turbo right? So that should have it

[Jim Robinson]

I don't have the Saratoga so I'm not sure, but that sounds reasonable to me. Wow, 41" is a lot of boost, be careful you don't blow the jugs off that puppy .

Jim

[iflysioux]

I know, I think the only other engines I know of that went up there were the huge round wasps on like DC-3's and stuff. In the checklist it says you have to let the turbo cool for 4 minutes, so that thing must be the size of a watermelon!

[shanwick]

I've done it with the 182RG, there's really not much to it. Like you say, make a copy the PA28 folder so you don't mess up the original. When you do this you'll need to change the title= line of each variant in the acft.cfg as no two installed aircraft can use the same title regardless of which folder they're in (they won't show up in the select aircraft menu if they don't have unique titles). Obviously you'll also need to change ui_variation=White blue & blue sky to something like ui_variation=White blue & blue sky Turbo for each variant as well. With that done it's just a matter of modifying the [piston_engine] section of the acft.cfg as shown below:

[piston_engine]
turbocharged= 0 //change the "0" to "1"
critical_altitude= 0 //this is apparently the altitude that the engine will start loosing power, change it to 12000 or so
max_design_mp=35 //this is already set to "35" on the Arrow, probably OK at that value

I think that's about it, you may want to experiment with the critical altitude and max_design_mp in the sim and set them where you like them. I didn't make any modifications to the .air file, I don't think there's any need to.

Jim

Jim

I've tried this on Flight 1's C172 Skyhawk which was interesting! However, one thing I did notice and that was when taxiing even with the throttle fully closed the aircraft would slowly increase speed and I had to be constantly applying the brakes. Do you have any idea why this should be so? It seems to be something to do with turbo aircraft as it also happens with Lionheart's Quest Kodiak.

David

[Jim Robinson]

Hi David, I wouldn't know why that happens unless turbocharging somehow increased the idle horsepower somewhat. It sort of depends on how the developer set up the engine modeling, they may have used an unconventional approach to engine modeling to achieve a certain power quality they were striving for, this isn't an uncommon practice in payware aircraft. It's not really supposed to do that, the idea is that it just maintains sea level power at higher altitudes.

Note that "turbocharged" and "turbine" are two different things. The Kodiak is powered by a turboshaft engine (a "jet engine" that drives a prop shaft rather than making thrust by accelerating hot gases rearward) and they do tend to require braking to keep taxi speed under control, you can pull the condition lever back to 10% or so to minimize or eliminate this effect BTW.

The turbo Arrow uses a turbocharged reciprocating engine (piston engine), the turbocharger is a device plumbed into the exhaust system, the exhaust gasses spin a small turbine which is connected to a small compressor via a shaft. The compressor rams air into the induction system under pressure, simulating the denser air found at lower altitudes, and therefore allowing the engine to maintain sea-level power at 12,000 feet for example.

I don't have the F1 Skyhawk so I can't check it out, but you might reduce the max_design_mp= value and see if it reduces the taxi speed runaway problem.

Jim

[shanwick]

Hi Jim

Many thanks for your comprehensive reply. I'll do a little experimenting and see what happens. I do have a taxi speed gauge - quite unrealistic, really - which I can set so that a constant speed is maintained whilst taxiing, thereby eliminating braking. I do like a turbo charged C172 as it enables me to climb at around about 1,200 fpm which is very useful in some parts of Norway and Switzerland!

David

[jgf]

With a little more idle power perhaps the brakes aren't up to holding the aircraft. Increase the brake power in the aircraft.cfg

[brakes]
toe_brakes_scale=0.6 <<<<< higher value = stronger brakes
parking_brake=1

[shanwick]

With a little more idle power perhaps the brakes aren't up to holding the aircraft. Increase the brake power in the aircraft.cfg

[brakes]
toe_brakes_scale=0.6 <<<<< higher value = stronger brakes
parking_brake=1

The problem is not that the brakes don't hold the aircraft as they do. Once stationery the brakes will stop the aircraft from moving. It's the fact that once the brakes are released and a small amount of throttle is applied the aircraft will start moving but then will continue to accelerate even though I have returned the throttle to idle. Applying the brakes will slow the aircraft but as soon as they are released the aircraft will accelerate again even though I have not moved the throttle out of the idle position.

David