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martyt
07-12-2004, 13:00
I fly the club's 1965 Skylane (182H) and have scoured the POH (or at least, the booklet that passed for a POH back in 1965) and there's no mention anywhere of what the best engine-out glide speed is.

During my checkout, I used about 88 mph, mostly because that's what the CFI told me to. But also because it's close to Vy.

So two questions:

*What is the proper best-glide speed for a 182H, and where is it documented?

*If the POH offers no guidance, is Vy or Vx a good guess?

ted teodoro
07-12-2004, 14:01
well, climb out in a warrior is 80 kts and the glide
speed i have used in training is also 80 kts. actually,
i think the vy is very slightly lower than that, like
78/79 kts...but i cant tell differences of one or
two knots on the airspeed indicator. when i
use the 172, i assume 80 kts as well. i know that
i will be in the neighborhood and i would be more
concerned about the ball being centered during
climb than whether i am at the exact vy.

another thing...v speeds assume gross weight.
so, even if the book says 80 kts, you are
flying alone or with a friend, what happens
then? your figures are again off the mark unless
you know the formula and you can do the math
in your head.

hmmm...
wasnt the plane placarded ?

ted

midlifeflyer
07-12-2004, 14:05
In the absence of a POH entry I wouldn't know where to look. Vy is a pretty good approximation, although Vglide tends to be a bit lower. I'd shoot for somewhere halfway between Vx and Vy.

Best way to find out is to go up try a series of airspeeds and see which one results in best glide. Of course, that will (a) only be an approximation because the prop will be windmilling and (b) be the best glide at the weight you flew at and will go up and down with gross weight.

Chances are it will be whatever speed the airplane settles at with the nose in a normal cruise level flight pitch attitude.

This is really one area where close really is good enough. With the variables that go into best glide speed (like weight) and the real glide range (like wind), close is all you really get anyway.

Jeff S KDTW
07-12-2004, 14:12
I'll check the 182P manual I have at home.

However, in the meantime, I checked the 177RG manual and found the data in the Emergency Procedures section (as a listing of airspeeds vs. gross weights); checked the 172P manual and found the data in the Emergency Procedures section; and finally checked the 172M manual and found it in the Operational Data section (as a graph).

It doesn't look like Cessna ever figured out where they wanted to put it. :)

crosswind
07-12-2004, 14:15
Look under "drop like a brick" in the POH.....found that out in my first hour in the 182. :)

midlifeflyer
07-12-2004, 14:16
Jeff's mention of other sources made me think. Some of these old manuals were very skimpy and assumed far more basic knowledge than the modern POH.

In addition to the type of chart Jeff mentioned, maybe there is a lift/drag/airspeed chart for the airplane?

gkrangers
07-12-2004, 14:21
Rent, the plane, cut the engine, and experiment :)

ilh
07-12-2004, 14:35
My school has an online W&B program for their planes. I just tried it for the 182S at find the following (KIAS):

(3100): Vx 63, Vglide 75, Vy 80
(2500): Vx 57, Vglide 68, Vy 72
(2100): Vx 52, Vglide 62, Vy 66

From this, it appears Vglide is about 0.3*Vx + 0.7*Vy (70% from Vx to Vy) in a 182S.

For a 172M-S, Vglide is generally 1-3kts lower than Vx.

--Lee

martyt
07-12-2004, 15:19
Originally posted by Jeff S KDTW
However, in the meantime, I checked the 177RG manual and found the data in the Emergency Procedures section (as a listing of airspeeds vs. gross weights); checked the 172P manual and found the data in the Emergency Procedures section; and finally checked the 172M manual and found it in the Operational Data section (as a graph).

"Emergency Procedures" section? I don't think they had emergencies back in 1965. At least not in a Skylane. ;)

I know the chart you're talking about - shows altitude on the left, distance on the bottom and a diagonal line for glide range. But that chart doesn't exist either in a 1965 POH.

The only data the POH gives is the standard cruise speed/fuel consumption/range at various altitude and power settings, plus takeoff and landing distances at various altitudes and weights. And that's it.

Jeff S KDTW
07-12-2004, 16:15
Marty -

From a 1976 182P Op. Handbook, Maximum Glide at 2950 lbs is 70 KIAS (80 MIAS), with flaps up and propeller windmilling.

Ridefree
07-12-2004, 16:39
The 182N I fly is 72 mph. Don't remember if it is in the POH or on the SURECHECK checklist I have for the plane. When I can get to the airport I'll look and let you know.

Bryan

jerryp
07-12-2004, 17:13
Originally posted by martyt
"Emergency Procedures" section? I don't think they had emergencies back in 1965. At least not in a Skylane. ;)

Correct. Anything built before 1979 had a non-standard POH, Now they're called AFMs and follow the GLENPWAAS format.

In the meanwhile Google produced a few sources for a "manual"

http://www.pilotshop.tv/pilotshoptv/98267.html

http://www.flightessentials.net/browseproducts/Aircraft-Flight-Manual.HTML


and a list of aircraft not required to have one
http://www.casa.gov.au/avreg/business/flightman/no_afmlist.htm

I've given up my cessna pilot's assoc. membership or I'd post a Q on the forum.

If the manual has lift to drag curves, it's where the 2 intersect.

Buzo
07-13-2004, 09:23
If you use full nose trim up at idle, you should get best glide. I was told at one point, that at full nose trim up that a single engine piston airplane will achieve best glide. Every airplane I have tried this in has worked.

ted teodoro
07-13-2004, 09:29
buzo

" full nose trim " please explain...

ted

Buzo
07-13-2004, 09:31
If you level the nose at idle and and put the trim wheel at the full nose up trim position you should achieve best glide speed.

As you slow down, you need to keep the nose level and prevent the plane from porposing, once achieved fly it hands off and you will be where you want to be.

midlifeflyer
07-13-2004, 10:18
Doesn't full trim nose up give you minimum sink rather than best glide?

Buzo
07-13-2004, 10:35
Originally posted by midlifeflyer
Doesn't full trim nose up give you minimum sink rather than best glide?

I don't know, but if you try it in a piston single the airspeed indicator indicates the published best glide

ted teodoro
07-13-2004, 11:34
oooooookay...

if a ( full nose trimming) = b ( speed on the ASI), and b =c ( published best glide ), then a =c !

an empirical truth, as presented by buzo...
i'll try it out next time i am up...

ted

pc
07-13-2004, 11:53
Buzo's formula is exactly what I was taught during my PPL flyinga 172. I haven't tried it in the Cherokee I fly now.

HIGHwing
07-13-2004, 12:31
I think full nose up trim is taught as an IMC to VFR conditions below as the plane will mush albiet stay level. I remember doing this manuver, but certainly not in connection with obtaining best glide. Seems to me best glide would be (cleanest config. feathered if possible) at between Vx and Vy as stated. It certainly makes sense to me.

[Warning no data in front of opinion maker, I'm typing off the cuff at work.]

midlifeflyer
07-13-2004, 13:00
HIGHwing, that's what I thought also. Guess I'll have to try full aft elevator on my next few flights and get some empirical data.

Ridefree
07-13-2004, 17:45
According to my 1971 Cessna 182N POH engine out set glide speed to 70 knots / 80 mph.

Bryan

HIGHwing
07-13-2004, 19:19
Ridefree -
What are the references for Stall Speed, Best Rate and Best Angle of Climb?

Jeff S KDTW
07-13-2004, 19:22
Originally posted by HIGHwing
Ridefree -
What are the references for Stall Speed, Best Rate and Best Angle of Climb? For 1976 182P:

VS0..... 48 KTS
VS...... 53 KTS
VR..... 50 KTS
VX..... 59 KTS
VY ..... 80 KTS
VA ..... 100 KTS
VFE ... 140 KTS

Ridefree
07-13-2004, 20:16
Originally posted by HIGHwing
Ridefree -
What are the references for Stall Speed, Best Rate and Best Angle of Climb?

Jeffs numbers above are close to the 182N, within 3 kts, but I do not have the poh at hand to give exact. If I can get away in the morning and get to the airport I will post the exact numbers, otherwise it will be next week. Due to the weather I am driving to the Cape instead of flying, so I will be leaving tommorrow evening on the 10 hour drive.:mad:

Bryan

HIGHwing
07-13-2004, 21:13
I used the 182S in MSFS 2002 for waaay to long now [Mother in law visiting] and came up with 61 kts, clean for a 590ft/min descent.

snaz
07-13-2004, 21:35
Originally posted by midlifeflyer
HIGHwing, that's what I thought also. Guess I'll have to try full aft elevator on my next few flights and get some empirical data.

i think you mean full aft TRIM.

full aft ELEVATOR will just make you stall.

I was taught the same thing in a 172 - that in an engine failure you can attain best glide speed (65kts) just by trimming back all the way.

the only problem is that when/if you do a go-around or touch and go, you have to push the yoke forward really hard on climbout to prevent an elevator trim stall.

Jedi Nein
07-13-2004, 21:57
Full nose up trim in a Cessna Single-Engine is Minimum Sink Speed per their Tech Guys that run around to the various mechanic seminars. This is a few knots slower than maximum glide. However, usually we do have a place to land, we just want to get the engine restarted again. I also find minimum sink lets the pilot stop having to fly the airplane and start working on the problem. The time it allows is phenominal.

Also, try pulling the prop back when gliding. You'll feel the airplane accelerate, and if you were watching the VSI, the sink rate will decrease from 800-1000 to 500-700 fpm down.

Per Ron at C.P.A.: 1.3 * Vs1 (CAR 3 & Aerodynamics for Naval Aviators). Vs1 is in the TCDS or in the Owner's Manual.

Fly SAFE!
Jedi Nein

midlifeflyer
07-14-2004, 07:04
Originally posted by snaz
I think you mean full aft TRIM. I think you are correct. Somehow my fingers refused to type out "trim" after the word "elevator".

And you are correct about the trim stall. But, if in fact, full up trim produced best glide, wouldn't you end up in that trim position anyway?

Jeff S KDTW
07-14-2004, 07:22
In anything other than a late model aircraft, how can we reliably know that the rigging (i.e. cables) is adjusted properly to produce best glide at full aft trim? In my non-A&P mind, it seems that cabling will stretch in Cessnas and will most likely not get adjusted unless it is grossly out of sorts.

snaz
07-14-2004, 15:43
Originally posted by midlifeflyer
But, if in fact, full up trim produced best glide, wouldn't you end up in that trim position anyway?

if you trim to relieve control pressures, then yes you would end up with full aft trim. but some CFIs I know don't want you to trim in that particular case specifically to avoid a potential trim stall - instead, they make you do the whole simulated engine-out simply pitching for 65 without any trim. that way your set for the go-around.

HIGHwing
07-14-2004, 19:35
In MSFS full trim produces a repeated trim stall. I found 62kts to be the best glide with repeated practice and some good old math.

Terry L in KY
07-14-2004, 20:46
Haven't chimed in lately, but I'm with Jeff, I wouldn't bet on full "nose up trim" would give you best glide...every time, in every plane. How close is your "neutral" or "take off" indicator in your aircraft (the ones I rent aren't even close).

As a side note, I'd personally hate trimming full nose up and then working a checklist only to find my knee knocked the ignition switch...turn it to both, the throttle was already firewalled. What a way to get in trouble.

Just food for thought

midlifeflyer
07-15-2004, 08:18
Originally posted by snaz
but some CFIs I know don't want you to trim in that particular case specifically to avoid a potential trim stall - To each his own, but I can't imagine not trimming for hands-off flight, potentially giving myself more to do while I'm handling a emergency.

martyt
07-15-2004, 09:05
Planning to take the Skylane up to about 12500 next week just to see how it handles way up high, and should have a *lot* of time in the way down to play with engine out scenarios. I'll try the full up trim business and see what happens...

ted teodoro
07-15-2004, 09:29
the one thing that doesnt fit well in my mind about
this " full nose trim equals glidespeed " scenario
is that it doesnt take into account the air quality.
i would think that glidespeed would also be a
function of the day/weather. it is hard to believe
that a certain nose up trim would produce the same
airspeed on the indicator in both the thin and humid
air of summer and the cold and heavy air of winter.

ted

Buzo
07-15-2004, 10:00
It is something for you all to experiment with. I have doen it in about 25 airplanes. It worked in summer heat and in Alaska winters. Just remember that best glide speed changes with weight. It will be slower if you are not at gross weight.

snaz
07-15-2004, 11:43
Originally posted by midlifeflyer
To each his own, but I can't imagine not trimming for hands-off flight, potentially giving myself more to do while I'm handling a emergency.

If it were a true emergency then I probably would trim it for the reasons you state. (and because i'd be landing to a full stop)

however, in a practice environment when you're going to end with a go-around or touch-and-go, what would you do with the trim? quickly take the trim out on your roll-out (T&G) while you're cleaning up? or after you full throttle it for go-around while holding the yoke hard forward?

probably wouldn't end being a big deal either way (i've done it both ways - not that big a deal if you just know what to expect) - just saying there are valid reasons for either way.

john1200c
07-15-2004, 15:40
The DE told me on my checkride that if you use full nose up trim after an engine out it would essentially get you to the best glide speed in the Warrior we were flying. We tried it and it worked great. Not sure if the same would hold in a 182, but, you may want to give it a try.

Edit: I see that somebody else told you this too.

HIGHwing
07-15-2004, 19:44
Marty,
Can I put $1 on a trim stall. Oh, and don't forget to breathe up there.

dan07usc
07-16-2004, 00:02
haha it sounds like you've all become test pilots.

cheers for pilots solving their own problems through safe and thorough expirimentation. emphasis on safe .

and watch out for that full trim stuff...if you forget about it on your go-around it can lead to an awful lot of unexpected sky in your windscreen.

Jedi Nein
07-17-2004, 14:34
Even better than producing the same airspeed every time, full nose-up trim in the Cessnas produce Minimum Sink Speed, whatever that may be for the aircraft's current weight, loading, and balance.

Fly SAFE!
Jedi Nein