Gauges question

[liquid_rockface]

Hi, I just have a few questions:

A) Flight Simulator 2004 doesn't really model fuel mixture very well, right? I mean, you cannot damage your engine by putting your mixture very low, and nothing will happen if it's too rich either. Did FSX improve on this?

B) Some aircraft (e.g. the Cessna Grand Caravan, which is kind of my favourite little plane) do not have an exhaust gas temperature gauge. Thus, it is impossible to know when and how to adjust the fuel mixture. From what I see, the real plane does not have this gauge either. Could anybody tell me what real Grand Caravan pilots do to lean the mixture in planes such as this?

C) There is also not outside air temperature gauge. How do you know whether it's a good idea to de-ice and turn on pitot heat? I mean, even the Cessna 172 has the OAT gauge, why not the C208 Grand Caravan!!??

There are some gauges in the Grand Caravan, like the Gas Generator RPM and Interstage Turbine Temperature gauges which I haven't seen on other planes. How do they help exactly?

I find it confusing sometimes how some planes have certain very specific gauges, and others don't have those, but have other ones. I mean, the Grand Caravan also doesn't appear to have Cowl Flaps, which are apparently so essential to the Beech Baron 58 and many other planes. The list goes on...

Help would be much appreciated!!

[Vampyre]

Hi, I just have a few questions:

B) Some aircraft (e.g. the Cessna Grand Caravan, which is kind of my favorite little plane) do not have an exhaust gas temperature gauge. Thus, it is impossible to know when and how to adjust the fuel mixture. From what I see, the real plane does not have this gauge either. Could anybody tell me what real Grand Caravan pilots do to lean the mixture in planes such as this?

There are some gauges in the Grand Caravan, like the Gas Generator RPM and Interstage Turbine Temperature guages which I haven't seen on other planes. How do they help exactly?

I find it confusing sometimes how some planes have certain very specific guages, and others don't have those, but have other ones. I mean, the Grand Caravan also doesn't appear to have Cowl Flaps, which are apparently so essential to the Beech Baron 58 and many other planes. The list goes on...

Help would be much appreciated!!

Pssst....It's a Turbine so therefore doesn't need to adjust the mixture. The gages you are talking about are typical of turbine engine guages you will normally see in just about any Turbine engined aircraft... well western turbine engined aircraft that is.. not sure about the others. The components of a turbine engine are effected by thermal stress. The repeated heating and cooling results in creep. The turbine uses an EGT (Exhaust Gas Temp) gauge and an ITT (Interstage Turbine Temp) gauge to measure thermal changes. The turbine section is exposed to the greatest amount of thermal stress which causes creep. Creep is the gradual elongation of blades as they are heated and can lead to catastrophic failures. Heat is a result of the combustion of the fuel air mixture. High pressure is a result and used to turn the turbine. No cowl flaps are required for a turbine engine. A turbine engine is very different from the reciprocating engines you are trying to compare it to. They are very different animals.

Tomcats Rule! Anytime Baby!

[liquid_rockface]

Well if it doesn't need fuel mixture control, then why is there fuel mixture control!? And what should it be set to? I normally pull it all the way back to about 16% mix when I am cruising.

Also (off-topic) the plane takes AGES to reach 18000 feet, the cruising altitude (thus I prefer 17000 as my cruising altitude) and I have no idea how it's supposed to reach some 22000 feet because from about 15000 feet I'm getting maybe 100ft/min climb rate! And this rate fluctuates quite a lot (including sometimes the plane dropping!)

Vampyre, you say it's a turbine engine, and therefore it has an EGT and ITT gauge, but that's the thing, it doesn't have an EGT gauge at all! (Did you mean Gas Generator RPM gauge maybe?)

Anyway, good to get an answer from a pilotting pro! I appreciate the help, and I hope I can understand this better. Are there any good websites that explain the difference between different engines?

As a side note, I was thinking how generally flight simulators are very unrealistic for the simple fact that they take the plane as being a perfect model. I imagine that planes are at least as quirky as cars. Some cars prefer things done one way, others another way. And depending on each situation you know your car and can adjust. In flight simulators everything is just so predictable!

E.g. starting a car. I had one car which was very difficult to start in the mornings (an automatic). You had to first pump the accelerator a few times, then turn the ignition, and then GRADUALLY and very accurately press the accelerator to add JUST the right amount of fuel so that the engine would catch and not die out due to fuel starvation or flooding. It was a very fine line. This is something not written in any car manual, but it was essential to drive my car. I am sure that planes are like this in many ways, and it is a pity that there are no "quirks" ever in Flight Simulator (even maybe just an engine taking a little longer to start on a cold foggy morning). I don't know how much this happens in planes though, because I guess they're much better maintained than cars.

[Vampyre]

Heres a good read on the different forms of reciprocating engines that are available.

http://www.ec.erau.edu/cce/centers/edwards/AMT280/Topic1p.htm

And an overview of the different types of aero engines.

http://www.allstar.fiu.edu/aero/flight60.htm

The gas generator on a turbine is also known as the compressor section. It's the part of the engine that recieves incoming air and compresses it and converts it to high pressure before sending it to combustion section of the engine.The letter "N" is used to abbreviate rotational speed, therefore the guage that reads Ng is showing gas generator rotational speed (also known as N1,N2,N3... up to however many stages are in the engine). The Gas Generator RPM guage the rotational speed of the turbine itself.
Different engine manufacturers measure turbine temps at different spots in the engine, and the instruments are labelled for the different areas that the temperatures are taken as listed below.
TIT (turbine inlet temp) is measured ahead of the first stage turbine
TOT (turbine outlet temp) measured just aft of the last stage turbine
EGT (exhaust gas temp) rather than measuring the temp within the turbine stages, some manufacturers opt to measure the temp further down the exhaust stream.
ITT (interstage turbine temp.) is just that, it is the temperature between the high pressure and low pressure turbines in the engine.

It has been my experience that, while there are aircraft with small quirks, there will not be much difference between the flight characteristics of two aircraft of the same type. There is very little tolerence for variables in how an aircraft flies. If an aircraft flies noticibly different from the others of its kind it is noted and judged to be either in or out of the normal operating range for the system involved. If it is out of range, a discrepancy is written and the "quirk" is fixed. If you have to do anything extraordinary to get the plane to do what you want then it is a safety hazard and needs to be repaired.


Tomcats Rule! Anytime Baby!

[liquid_rockface]

OK by quirky I also meant like that in condition A B and C you will need to de-ice and put on pitot heat, or do some other preventative measure, or you forgot to lean the mixture and the engine is running rough, or it's too lean and you have knocking. Or maybe there is something strange happening and you need to run a checklist for abnormal occurences. Yes, possibly it does need maintenance then!

You still didn't explain why the Grand Caravan has a fuel mixture control lever, even though you claim it doesn't need it. And how can you measure how lean you need your mixture when none of the gauges change when you change the setting!

Thanks for those links I'll look through them now!

[Vampyre]

OK by quirky I also meant like that in condition A B and C you will need to de-ice and put on pitot heat, or do some other preventative measure, or you forgot to lean the mixture and the engine is running rough, or it's too lean and you have knocking. Or maybe there is something strange happening and you need to run a checklist for abnormal occurences. Yes, possibly it does need maintenance then!

You still didn't explain why the Grand Caravan has a fuel mixture control lever, even though you claim it doesn't need it. And how can you measure how lean you need your mixture when none of the gauges change when you change the setting!

Thanks for those links I'll look through them now!

You had me scratching my head on this one. There is no carburetor on a turbine engine and no reason to adjust the fuel/air mixture going to the non-existent cylinders. Then I thought about it a little and am wondering if you are talking about the fuel control lever. All the fuel control lever does is set a minimum fuel flow into the engine so you don't accidentally shut it off or stall it in flight. No mixture lever at all. I did find a checklist for the C208 while searching vainly for a fuel mixture control lever for a PT6A-114 engine in a C208. Took only about an hour on the internet...

http://www.feelthere.com/caravan/caravan.doc

Tomcats Rule! Anytime Baby!

[liquid_rockface]

Wow I think you're right! I feel like a real clot now! I think I was thinking all along that the Fuel Condition (not control) Lever was a Mixture Control!

So anyway, when you cruise should you lower the fuel condition lever to a low percent? Or keep it plugged at 100% the whole flight? I don't quite understand its purpose really...I mean, there is a fuel cut-off switch to cut off the fuel...

[liquid_rockface]

Another, totally unrelated gauges question:

The VOR needles in FS are almost impossible to set exactly on the correct point for the exact number of degrees that you need. I always (on the HSI) have to hover to check the exact heading, or on the VOR OBS I just have to estimate that it's about where I put it.

My question is: In real planes, do the rotating knobs for VORs and similar devices go click click, so that you can count the clicks to work out how far between the 5 degree marks you need to move? Or do you also pretty much just guess whether you're on 133 degrees or 134 degrees?

[Vampire14]

Wow I think you're right! I feel like a real clot now! I think I was thinking all along that the Fuel Condition (not control) Lever was a Mixture Control!

So anyway, when you cruise should you lower the fuel condition lever to a low percent? Or keep it plugged at 100% the whole flight? I don't quite understand its purpose really...I mean, there is a fuel cut-off switch to cut off the fuel...

There is a seperate lever just to simplify things really - and leave it at max position while flying - can move to low when taxiing etc.
You will notice that there is no condition lever in a jet but there are still two seperate lever inputs into the FCU, as ground idle and flight idle are controlled automatically. For instance you will see two seperate levers into the FCU on the Viper 680 that move in different parts of the total throttle lever travel to control fuel shutoff etc. But once past idle (flight or ground decided by the FCU) then the 'condition' lever doesn't move, just the throttle lever to tell the FCU you wanna go fast!...and I can tell you that setting this lever travel for both levers and the right overlap, back pressure etc etc with ur feeler guages is a pain in da assss!!

There will mostly always be a mechanical way to isolate or cutoff the fuel supply directly also, so to complement ur fuel cut-off switch.

In the C-130 you don't even control fuel flow, you just effectively tell the engine how hot you want it,or controlling TIT, and the TD valve does the rest by adding some gas which results in more power.
Now to really confuse you - you will notice in the C-130 there is a seperate condition lever and throttle lever for each engine, while in the P-3 there is only a single lever per engine.......and they both have the same basic engine - T-56:bigeyes: ....lol.

[Vampire14]

Another, totally unrelated gauges question:

The VOR needles in FS are almost impossible to set exactly on the correct point for the exact number of degrees that you need. I always (on the HSI) have to hover to check the exact heading, or on the VOR OBS I just have to estimate that it's about where I put it.

My question is: In real planes, do the rotating knobs for VORs and similar devices go click click, so that you can count the clicks to work out how far between the 5 degree marks you need to move? Or do you also pretty much just guess whether you're on 133 degrees or 134 degrees?

No clicks in my experience - if there was I would be worried. Nice and smooth to rotate.
Remember the res in real life is a bit better that in MSFS so it is nice and easy to set it tight :bigsmile: