Some Flight Sim Stuff

I was playing FS2004 last night and decided to try flying the pattern the skydiving airplane takes when climbing to altitude (13000 AGL), which is basically just a box with the last side being right over the airport.
I took off in a King Air 350 and realized on takeoff that the scale of the terrain is WAY off. The distance between the end of the runway of KTVY and the Great Salt Lake seems WAY too short. Is incorrect scale or distance of terrain or objects something you notice in FS a lot?

Also, could somebody please explain gyroscopic precession to me as it applies to an airplane?

fs is super accurate uless you have an aftermarket terrain than all bets are off. i would expect the aircraft configuration is off more than i would expect the terrain is off. you can edit the flight characteristics of a plane in notepad, but editing the terain mesh is far more complicated. so if there is an error and i doubt there is, i would suspect the plane or flight sim settings before i would think the terain was messed up. i have my graphic settings very low for high frame rates, and there are lots of errors like rivers flowing up and over small hills, but when i slide the details to max its super accurate but i cant fly at 7 fps. in max settings they are accurate to less than a meter, and show over 1million polygons at a time on the screen.

as far as gyroscopic precession you need to have a gyroscope and hold it in your hands and it will explane itself to you. or a bicycle wheel while you stand on a lazy susan same idea. its also why when you ride a bicycle once you get moving you stay upright without falling over like you would at slow speed.
basicaly hold the gyro straight out in front of you like a chip stick, and flick it up 90 degrees, it wont do it,it will twist right out of your hand 90 degrees to one side or the other depending on which direction its turning. so as you speed up or slow down as far as the gyro is concerned you are changing and it turns 90 degrees from the direction you want it to go. its not important that you know how it does it, or how gravity works, its just that you know that it exists and can anticipate what it will do.

While the above is true…

Gyroscopic Precession is not very apparent to most student pilots. It is the least noticeable of the 4 left-turning tendencies that most training aircraft exhibit. (the other three are P-Factor, Spiraling Slipstream, and Torque) Torque causes a rolling moton, the rest are yawing motions.
It is MOST noticeable during two specific manuevers, 1.)to pilots of tailwheel aircraft during takeoff; and 2.) during stalls.

I’ll explain the first one.
When the aircraft begins the takeoff roll the aircraft sits with the tailwheel on the ground, nose high. As the aircraft gains speed, the pilot pushes forward on the yoke, raising the tail off the ground. This moment is precisely when the Gyroscopic Precession rears it’s ugly head.
As the aircraft pitches forward to raise the tail, the propeller disc is imparted a force on the upper and lower parts of the disc. Basically, it’s like someone is pushing on the rear of the prop when it’s at the top of it’s arc and pushing on the face of the prop when it’s on the bottom of the arc.
This force, though, is acted upon the aircraft 90 degrees in the direction of rotation due to gyroscopic precession.
For most training airplanes, the propeller rotates clockwise when viewed from behind. So the forward force on the top of the prop actually acts on the right side of the prop. And the rearward force acts on the prop on the left side.
That is why the aircraft wants to yaw left very strongly at the moment the tailwheel is raised.

The same happens during a stall, when the nose drops quickly the airplane wants to yaw left.

The above is backwards if you’re flying a Yak or a Nanchang.

FS Dreamscapes mesh with Intermap’s data is very accurate, but you need a fast gaming system to run it.

I was a physics major, and I still get paid for doing physics, and after 30 years of it, I still don’t have a gut-level understanding of gyroscopic precession. I like cfijames’s valiant swing at it, and he’s got it right, but if you still don’t understand it, don’t feel bad. I still handle it just by the mathematics, because my intuition fails me on this topic.

I looked around for a while to find an explanation on the web. There are YouTube videos that show it happening, but don’t really explain it. The Wolfram site and several others show the mathematics but with no figures, and that also comes out opaque. After 30 min of searching, this is the one I liked the best.
It comes pretty close to making it seem reasonable. :wink:

Translating that to the airplane case…
The angular momentum of the propeller and the engine (crankshaft etc.) is an arrow pointing along the shaft, either straight forward or straight aft. If the propeller turns clockwise as seen from behind it, the angular momentum arrow points forward. If the propeller turns counterclockwise, arrow points aft.

The torque from lifting the tail is like another tiny arrow pointing always to the left, and that torque makes the angular momentum arrow change in that direction. (If the tail drops, the torque arrow points the opposite way – to the right.) If the angular momentum arrow was pointing forward, the plane veers left; if it was pointing aft, then the plane veers right instead.

Clear as mud?

Gyroscopic precession is far more pronounced in large radial engined single engine aircraft due to the spinning engine mass. I would guess the OP is trying to “fake fly” some old war bird. :slight_smile:

Edit: And as CFIJames stated, precession affects the lateral axis of the AC.

I would guess the OP is trying to “fake fly” some old war bird.

Heh, nah. I actually was just cranking the realism settings on FS2004 and noticed that it said gyroscopic precession is something you can turn on or off. I looked it up on Wikipedia and learned that if you have a gyroscope and set it on a table while it is spinning, it will wobble around its axis due to gyroscopic precession, but I wasn’t entirely sure how that applied to an airplane.
I read some more and now I think I sort of understand. If you pitch up or down, you are pushing ‘against’ the gyroscopic motion of the propeller turning clockwise (from the pilot’s perspective) which imparts a force to the right or left depending on pitch up or pitch down.
Here’s a way to feel it for yourself: Find something that rotates that you can hold in your hand. Turn it on (or start it rotating, which ever) and hold it so the shaft of the spinning object is perpendicular to you (parallel to the ground). Turn the object on that same axis in the direction it is rotating. You probably won’t feel anything.
Now try to move it all around. You should feel force fighting against you wobbling the spinning object.

Same thing with an airplane. When you bank the wings, you are turning the plane on the same axis the engine is rotating. When you pitch the airplane up or down, you are turning it against that rotational inertia which imparts a force which banks the plane left or right, depending on if you are pitching up or down.

At least that’s what I gathered from what I read from you guys here on the forum and a few sites. I admit I could be wwaayy off. :smiley: … ne&f=false

My first thoughts when first reading this was the effects of gyroscopic precession on the heading indicator. In a nutshell, the effects of precession will cause the heading indicator to lose accuracy after a period of time. The more you turn the airplane, the more it will lose accuracy within a given time. I think turning the setting off in Flight Sim will keep you from having to worry about resetting the heading indicator every now and then. You will lose realism if you do that. :wink:

I used to explain to my students what is happening and what you might notice in the plane, with the caveat that they shouldn’t get hung up on the physics of it, other than being able to explain it in a few sentences. “Why does this happen?” I’d say, “Because it’s the law. If you don’t like it, take it up with Newton!”

Needle is right as far as flight sim goes. It relates to the heading indicator. I practice instrument approaches on mine, and keep it turned on so that I have to reset it to the mag compass. I don’t get the feel of flight from the sim , but I can keep the procedural side of it fresh in my mind.

I have the terrain settings a bit low, so that is probably why it is a bit inaccurate.

As for the gyroscopic precession, I think gyroscopic precession is only for the heading indicator, but there ARE gyroscopic forces and torque that act upon the airplane. I was flying a Mooney M20 and noticed whenever I bank up, the airplane pitches to the right, which I believe is caused by those two things. You can turn them off in the realism settings, but I just leave the realism at 100%.

I am using the keyboard since I don’t have a flight yoke yet :frowning: It is really annoying because there really is no fine adjustments. I end up having to use elevator trim way more often than is probably necessary in a real airplane :slight_smile:

To counter the gyroscopic turning of the plane, should I trim rudder or ailerons?
I also noticed the Mooney seems to require a LOT of throttle to get it to move on a taxiway (parking break is confirmed off!). Is that a Flight Sim thing?
I really really just need to get my PPL so I can fly in a REAL plane :smiley:

I hear ya! I wish I had the yoke, throttle quadrant, and pedals. Do you have FSX?

I do have FSX, but I use 2004 instead. My computer is in desperate need of an upgrade and FSX runs just a bit too slow, even at the lower end of the graphical settings. 2004 seems to run better and look a bit better. My brother has a Macbook Pro that will run FSX on pretty high settings at 40-50FPS (sometimes more). That looks GREAT.

I, too, wish I had the yoke, throttle quadrant, and pedals. If I was going that far, it might be worth it to find the front end of a scrapped Cessna 152 or something and modify the panel to use screens to simulate the instruments and use a projector to project the rest onto a screen outside the cockpit. …That’s getting a bit expensive.
Anybody have any idea how much the scrapped front end of a Cessna (or any other plane for that matter) would cost?

quake if you enjoy fs without a stick, you will enjoy it 1000% more with a stick. its like watching a black and white tv and moving to a color tv.

do you know how to do ils aproaches and landings? using the needles on nav1? to be honest i can take off then start using auto pilot fly to my destination using the vor’s then landing using the autopilot and ils guages and never touch the joystick and never look out the windshield, i set clouds at max overcast and rain and visibility 1/8 mile and hit the numbers every time using the ils procedures.

Yeah, my brother has a flight yoke. It makes it 100 times easier to fly. With the keyboard, it’s damned near impossible to land right. It’s like if I’m just above the runway and I want to flare, I press the up arrow to pitch up a bit, but there is no fine control, so I pitch up WAY too much. I’ve messed around with the sensitivity settings a bit and have gotten it to be okay, but landing is still very difficult.

I generally fly VFR, navigating using VORs (Or is that IFR? :slight_smile:). I just flew from KU42 (Salt Lake Airport #2) to KLAS (McCarran Airport, Las Vegas) in the Mooney Bravo using VORs the whole way. 1 hour, 50 minute flight! I wish I had my PPL, complex airplane endorsement, and that plane…It takes 4 1/2 - 5 hours to drive to Vegas from SLC. I can only imagine being able to get there in less than 2 hours. I’d go and get lunch in Vegas with some friends and come back.
Another hard thing with the keyboard is trimming. I end up ‘steering’ with the trim while trimming, which I’m sure isn’t how you are supposed to do it.
Not going to lie, I don’t have an especially firm grasp of landing procedures. I do follow the in-game checklists for each aircraft, but still…
I’ve noticed it takes a LOT of throttle in the Mooney to get it to taxi (And yes, the parking brakes are off.)

Can anybody recommend a good joystick/yoke? Probably don’t want to spend more than around $150 at most.

I’ll have to try an ILS approach.

I don’t know how to do the ILS. I like flying VFR, but sometimes I set it on “stormy weather” where it is raining, high wind, and a high overcast. Could you give me some pointers on the ILS?

Nope. You can navigate using instruments while flying VFR. The difference between IFR and VFR go waaaaaay beyond navigation.

I have THIS YOKE. It’s great. All the various buttons on it can be set to operate flaps, landing gear, autopilot, window views, etc. Well worth the investment!

Try reading THIS
Also, search youtube for videos - I’m sure you’ll find quite a few.

OK, thanks! That looks like some good stuff. :smiley:

that tutorial is good but you can search youtube and find a ton of them.

here are a few also im not sure but if you create a flight using ifr instead of vfr, the CT will talk you all the way, just as you turn to the runway heading you can switch on appr hold button on the AP and glide down to the airport.

also you will be able to learn how to read the approach plates. here is my favorite nav site, and i will link a few ils approaches from youtube, where they walk you thru everything needed to do.

- YouTube)

almost every flight i take now involves either night or instruments.
and i have fine tuned the Lancair Legacy to make it as accurate as possible, thats why i use it so much.