Cessna 172SP Antennas and Static

[Stainless Skills]

The 172SP's I fly at flight school have two static ports. One in front of the cabin on the left side of the fuse and one behind the cabin on the same side. One is for the instruments and the other, autopilot. Which one is which? I am supposed to find out. I have an information manual but after looking through it for 10 minutes I have gotten nowhere.

Also the 172SP has several antennas and I need to know what they do. The two directly behind the cabin are for com1 and com2, that is pretty obvious, then there is a smaller black one that is for the emergency locator transmitter. Then there is a bigger one on top of the wing and a small dorsal fin under the fuse. Which ones are for the transponder or other things?

I would love some answers but what I really need is a good resource to find out what antennas go where. The internet is of no help right now. I have searched for 15 minutes.

Also, what does alt static on the check list mean? And where could I find a checklist description of what every thing is you are doing. For example, before the 2nd lesson I was going through the checklist and ran across the Tach and Hobbs, I did not know what those meant and had to ask my instructor.

Thanks, John.

[Mokken]

All depends on the equipment:

The two antennas on the tail, on the upper part of the vertical stabilizer where the rotating beacon is, they are the NAV antennas for the VOR's and Localizers.

Two antennas on the wing right in the middle, they are the Communication antennas. and in the middle of those two if it has a GPS installed you will see like a small rectangular box, that's the GPS antenna and if it also has a small metallic tube sticking out that's the Outside Air thermometer.

on the tail behind of the rear windows you'll find the ELT antenna.

and on the belly of the plane you'll find the antennas for:

the NDBs if the airplane is equipped with an ADF
marker beacon antenna... for the ILS approach
and the little fin is the transponder antenna

[hpapilot]

The 172 I fly has no autopilot, and the only static port (for the instruments) is on the left side in front of the cabin / right behind the cowl. I'd assume on your plane the one behind the cabin is for autopilot.

Alt Static is the Alternate Static source for the instruments, used in case the main static port is clogged, and usually comes from inside the cabin. To check it, simply pull out the alternate static source handle. If it works right, you should see a "spike" on the VSI.

Hope this helps.

RJ

[hpapilot]

Oh, the other items. Tach is short for Tachometer, the instrument that shows engine RPM. The Hobbs is the instrument, normally on the far right side of the panel, that shows the amount of time that the electrical system has been turned on in the life of the plane. The POH may have some expanded explanation of the checklists, but some of these basic items you just have to ask about. Hard to go wrong that way.

[BreadBowl]

The transponder antenna is usually a small antenna with a "ball" on top of it, and all the ones I've seen are usually located on the bottom of the fuselage.

I think on the checklist, the references made towards the Tach and the Hobbs may be regarding the time shown on both. Since not all airplanes have a Hobbs meter, the Tach will also record elapsed time that the engine has been running. When I used to work out at the airport near my house a few years ago, we recorded time using both the Hobbs and the Tach time. It's awesome that you're learning to fly, though. I started taking lessons when I was 10 and it's something that I can't imagine myself ever not doing. I literally have physical effects from not flying. But anyway, I hope you get your license. You won't regret it, I know.

And RJ, I have nothing to say to you. You better be out at the field when I get out there in 20 minutes.

[Stainless Skills]

No kidding I can not wait to finish. I have already read through the whole manual that came with the 25+DVD's for the ground school that you are supposed to do the DVD's take way to long and take 10 minutes to say something that could be picked up in 10 seconds, oh well. I pretty much understood everything but the weather here in Texas is not very understanding toward me getting hours in. I have actually made 10+ appointments with my instructor in the past and have only been able to follow through on 2 of them because of clouds / weather.

I have got 2 flights in so far though. Flying is awesome, last flight I got to taxy/fly the whole trip, take off and land, it was pretty sweet.

I am always finding myself reaching down to use that trim wheel because it is so frustrating not being able to have a center of pitch like we can with our aerobatic plane when we climb, dive, or change throttle settings. Its weird how the cessna's have that down thrust elevator geometry cg thing going that makes them horizontally stable. Using the rudder during turns is pretty sweet, but I dont like how you cant just point the nose in one direction, up or down, and fly there. Oh well, guess its better that way...

[jack01]

[quote=Stainless Skills;258753] Its weird how the cessna's have that down thrust elevator geometry cg thing going that makes them horizontally stable. quote]


Along those same lines, Cessnas don't use right thrust. The vertical stab is crooked.... Just seems like angled engine mounts would have been much simpler.

[GremlinX]

Ha, Yeah, a local goob was screaming that the rental 172 we use a lot has a bent vertical stab. I said huhh? Hee hee... The 35% Godfrey is the same way, some angle built into the stab itself... This is good to know. Good question SS...

[Stainless Skills]

No kidding, it does not make any sense because the speed of the engine does not change with the speed of the air over the virt stab. And then you get lots more right turning tendencies on take off. Oh well.

[krashmaster81]

Hey Skills,

I did most of my flight training in Oklahoma so I know exactly what you are experiencing with weather! I've gone for months in the winter where I couldn't fly, very discouraging...

With regard to the "stability" of the Cessna, you'll find this to be a SUPERDUPER nice feature when you are doing your instrument training! Imagine looking away for a second to change a freq. or find a chart... and you come back and the plane is now pointed 30 degrees down and 30degrees to the right... not fun when you are in the clouds! I think you'll find that the Cessna handles just how a small general aviation plane should handle! They weren't always this way, however. The early (50s and 60s) Cessnas had a different airfoil and wing incidence and lots of other geometry. They fly completely different.

When you come up with a question like the ones you posted here earlier, take it to your instructor as well. Asking for his help is why you pay him! And it shows him that you are really willing and eager to learn. Judging by your questions so far, it seems to you are. The more you ask of him the more you will get in return, and he will be able to tailor his teaching to your learning style. But to do that effectively he'll need some feedback from you. So don't rely entirely on internet for all your answers! BTW, I totally agree that the DVD's take WAY too long to explain some things, text can be so much quicker!

One of the best things you can do for yourself is study up for the next day's lesson. Have a general idea as to what topics will be covered, and the layout of the lesson. You should have a training syllabus that will outline the entire course for you. This way you already have it in your head what you will be doing that day during the lesson. It makes things go much smoother for the student and the instructor! Stick to it and you'll have a blast!

-Matt

[GremlinX]

	Quote: Originally Posted by Stainless Skills
	No kidding, it does not make any sense because the speed of the engine does not change with the speed of the air over the virt stab. And then you get lots more right turning tendencies on take off. Oh well.

You think the same amount of air is coming off the prop and is going over the stab does not change? I am baffled at what you mean.......

[vernonf]

What I have done for every plane I've ever checked out in was buy the specific Operators manual for the plane. It will have the info you want. Your cfi can show and tell also.
good luck

Forrest