“Fun” with Simulations

By lex, on July 4th, 2009

So, the 1976 Cessna 177RG ** Cardinal operated by the flying club is back in service after a lengthy maintenance interval, and – having allowed other club members the privilege of putting the first dozen or so hours on the machine after the layoff – your correspondent is all set to get reacquainted with her tomorrow, with a club CFI riding shotgun only for the safety that’s in it.

It’s a so-called “complex” aircraft by general aviation standards, having wheels that come up and a constant speed propeller. Operators of the Cardinal are graced with an active forum of support known as the Cardinal Flyers Online, producing everything from expert opinion to earnest conjecture on such arcana as after-market exhaust systems (Power Flow Systems tuned exhaust for the 177 is considered quite the thing, providing airspeed increases that would amount to pointer error on a fighter, as well as certain specific fuel consumption efficiencies) and cabin door hanging. A quite bewildering degree of technical data is provided daily – sometimes more often – in the form of a digest sent out to members in good standing.

Having registered, a couple of local Cardinal operators from Gillespie Field graciously offered me the opportunity to bounce questions off of them, which I was certain to do whenever the plane came up again. One even offered a cautionary tale.

Seems the club had a different retractable Cardinal back in the day, before a relatively low time, but certificated private and instrument pilot with 18 hours in the C177RG flew his family up to South Lake Tahoe on a warm summer’s afternoon. The airport is high, the day was hot, the aircraft overloaded and the flight sadly abbreviated * . High, hot and heavy is quite literally no way to go through life; the plane was destroyed, there were no survivors.

Well, it’s all quite a lark until the trees and terrain loom up on you with no excess airspeed and the VSI needle trembling around zero, which is something you scarcely had to worry about in aircraft where performance charts were only consulted for annual check rides. But, perhaps out of morbid curiosity, I determined to set up the same scenario as the Tahoe tragedy on a desktop simulation and see what was what.

I’ve got two simulators on my machine, X-Plane, by Austen Myers for the Mac side, and Microsoft’s Flight Simulator X ** (FSX for the cognoscenti) on the dark side. I booted up X-Plane, set up a 177RG on Runway 18 at South Lake Tahoe (not the preferred departure routing, but the way the mishap flight took off), over-loaded the machine with fuel and cargo, dialed the density altitude up with altimeter setting and temperature and adjusted the winds for a quartering headwind.

Even with the engine running full rich on the mixture control (not recommended for high density altitudes), I got the simulation airborne with room to spare, and – although it would have been hair raising – easily cleared the terrain and trees on the departure end. (Although it was not possible to replicate the characteristic downdrafts at KTVL’s RW18 departure end.) Not as who should say “easy”, but definitely in the realm of “wouldn’t do that again” do-able.

Switched over to the dark side, loaded up FSX and chose AOPA’s Cardinal 177 fixed gear simulation, since I couldn’t find a (free) RG on line. The fixed gear Cardinal apparently climbs better than the RG, although it trues out a little slower in cruise, both on account of the increased weight and decreased drag of the retractable gear.

Made the same changes in weight (keeping all things in proportion), winds and density altitude for the FSX simulation, took RW 18, ran her up and promptly – well, agonizingly – flew her into departure end terrain with the stall horn blaring. She just wouldn’t climb.

Those had to be some awful moments for the pilot in command.

Made a second attempt with the throttle leaned out, full brakes on until the manifold pressure had topped out and held the machine on deck until achieving not just rotation speed but best climb angle and just barely cleared the trees and terrain at the departure end. Which I can tell you would be a damned hard thing to do with family in the machine, since it took nearly the whole runway with the departure end terrain and trees growing ever closer to get to Vx prior to raising the nose.

There are no real conclusions on the relative merits of X-Plane vs FSX to draw there, since the Cardinal model used by X-Plane was provided – free of charge – by a third party outside Myer’s domain. Nor yet would I recommend hanging my hat on the accuracy of any desktop flight simulator when it’d be my own bacon cooking, no matter how advanced. Although I do have to admit it is good, cheap practice for IFR procedures for those of us pampered in days gone by with gratuitous quantities of excess thrust, GPS-aided inertial navigation systems, digital moving maps and ejection seats, worse comes to worst.

Still, I found it interesting. And a good reinforcement of the notion that there are certain things cannot be taken for granted in a normally aspirated piston-engine single. Nor are performance charts the kind of thing you only break out annually if you want to spend any time at all flying them.

 

* 09-08-2018 Links Gone; no replacements found – Ed.

** 09-08-2018 Original link gone; replacement found – Ed.

                      

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Filed under Best of Neptunus Lex, by lex, Carroll "Lex" LeFon, Carroll LeFon, Flying, Lex, Neptunus Lex

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