High altitude t/o with stock 170

[buzzlatka]

I am assuming the part is the
Ratchet ?
Part number 0510171-1?

[GAHorn]

Fourth notch of flaps-----------George, there goes that orginality

Actually..its the replacement part Cessna sent .. they are out of the earlier part and approve the later. (It's even on the revised TCDS) I replaced mine due to the discovery of the 20-deg notch being worn. I guess I could have filed/dressed it.....if I'd cared to keep only FOUR notches of flaps.... with the new part I get FIVE notches.

Yes...Buzz.... it's called a "ratchet" in the IPC .... however the part Cessna sent had a picking tag with it which called it a "sector".

[buzzlatka]

What is the new part #?


Glad to see the fires didn't get you george!!!

[GAHorn]

What is the new part #?


Glad to see the fires didn't get you george!!!

The part no remains 0510171-1. It's a bit steep for what it is....$140.... bluEldr would likely open a modification-center if he could get more than a few orders. (Hint: A surplus dealer who bought from service centers going out of business sold it to me for $22 including postage....unfortunately, I bought it in 2000 along with some other parts from him when Austin shut down Mueller and he's no longer in business. ) But I have good news as well.... see the MX LIbrary:
http://www.cessna170.org/forums/viewtop ... =26&t=8901

Re; the fires: Thanks! The one off to our North was finally brought under control with a Skycrane helicopter. It was interesting to watch him work. It's the exact same one as in this picture (I don't know if this pic shows him dropping retardant...or muddy water....but I watched him suck up plain, clear water from Lake Travis and lay it down ahead of a fire-line to prevent further advancement of the flames..and he was GOOD!
:

s_t34_05029911.jpg

[cessna170bdriver]

I was watching a couple of Skycranes and a DC-10 work our fire Monday; impressive! The Skycranes emptied a small local flood control reservoir (our wet winter and spring was the only reason it had ANY water), and had to start going to a small lake a few miles away.

[buzzlatka]

And now back to the topic

At 4400 ft elevation, 90 degrees, and gross weight the 170 uses less runway when the flaps are at 20 degrees than flaps up. As for obstical clearance.....it didn't matter cause I had to circle anyway to get over the sierra.

[canav8]

Hey Buzz, so I am curious. I want to know if you had someone watching the instruments or did you observe yourself the speed. The next question is, is your aircraft IFR? Since you dont want flight instruction, I am not offering any. I am just curious if you knew what your rotation speed was? The only thing I will say is even though someone else would like to have a technical discussion, Not every 170 is the same and that Owners manual numbers lie. I am glad you did not have to use super hero pilot skills. regards, Doug

[buzzlatka]

I used runway distance markers. I did 2 takeoffs with flaps up and 2 with 20. I seemed to lift off about 2-300 ft shorter with the flaps 20. The airplane is IFR. I normally lift off in the 40 knot range on my airspeed indicator at gross flaps 20 and somewhere near 45 knots flaps up. When I am light I don't even have indicated airspeed for liftoff and initial climb.

[GAHorn]

IAS can be disregarded in takeoff ROLL measurements. For one thing, the indications are unrelieable in that range and for another, I doubt any of our 170s are equipped with sufficiently-long probes to accurately sample, nor are connected to instruments sufficiently accurate or calibrated to be worthwhile.

The best method likely available to us when making such comparisons is a full-up elevator takeoff in any given configuration and an observer to mark the point of main-gear lift-off.

And now back to the topic

At 4400 ft elevation, 90 degrees, and gross weight the 170 uses less runway when the flaps are at 20 degrees than flaps up. As for obstical clearance.....it didn't matter cause I had to circle anyway to get over the sierra.

The relationship of flaps-deployed/un-deployed take-off roll to clearing the Sierras by circling is not germane to the discussion, in my view, because it does not take into account the theoretical engine-failure after takeoff situation when the maximum effort might mean getting back to the airport or not. In other words, theoretically at least, it's best to utilize the method which gives the shortest distance to clear obstacles near the takeoff path at the airport....not a geographical obstacle miles away. (Using the latter instance would be like using only flaps-deployed for every takeoff because I usually takeoff in the Houston area even though the destination is Salt Lake. If I stuck with that philosophy leaving the Westheimer airport (O07) I mightn't ever get farther into my trip than the power lines at the west end of the runway! A flaps UP takeoff gives better clearance of those obstacles even though the takeoff roll is greater.)

In other words, Buzz..... when that valve sticks shortly after lift-off.... whether or not that takeoff was made flaps up or deployed might be very important indeed....clearing the Sierra may be the least of your worries!)

[canav8]

George wrote: IAS can be disregarded in takeoff ROLL measurements. For one thing, the indications are unrelieable in that range and for another, I doubt any of our 170s are equipped with sufficiently-long probes to accurately sample, nor are connected to instruments sufficiently accurate or calibrated to be worthwhile.

The best method likely available to us when making such comparisons is a full-up elevator takeoff in any given configuration and an observer to mark the point of main-gear lift-off.

Finally George we agree on something. That was exactly what I was thinking and why I asked! Doug

[GAHorn]

...Finally George we agree on something.... Doug

Whaat...???

I thought we agreed on a LOT of things! (Women, beer, Cessna 170s .... all being great subjects ...)

[buzzlatka]

Back to the original question.
What gives you the shortest takeoff roll.
Answer.
20 degree flaps in my 52 170b.

The theoretical engine-failure after takeoff situation when the maximum effort might mean getting back to the airport or not was not part of the discussion.
IAS or groundspeed or TAS was not part of the discussion. I mentioned it only as an answer to Doug's question.

Sidenote/thread creap Today I returned alone with full tanks and 68 degrees. 2 takeoffs with 20 degree flaps and 2 clean there was about 300ft difference in the roll. Clean being longer. They were using the north runways today with a south wind so I had about a 7 knot tailwind for my takeoffs. Shorter rolls but my groundspeed was a lot higher and I noticed my tires vibrating a bit. The tires are pretty new but I wonder if it is a balance issue or a combo of high speed, 8 inch tires, and 180 gear. It was probably my fastest ground roll to date. Anyway I guess that could be a new topic also.


More Thread Creap.
I really have enjoyed the discussion on flaps. I am going to try and find a flap rachet with the 10 degree notch. I am interested in testing out the 10 degree setting vs the 20 degree setting at my normal place of operation and then starting another thread.



That thread will be entitled 10 degree vs 20 degree flaps. Which one gets me out of a very bumpy 1200 ft strip with big trees a the end the quickest shortest and best. Note I'm screwed at this place if anything happens on takeoff. At reno I had 9000ft of runway. I could have lost the motor, landed, started it up, taken off, and repeated the cyle a few times.

[Bruce Fenstermacher]

That thread will be entitled 10 degree vs 20 degree flaps. Which one gets me out of a very bumpy 1200 ft strip with big trees a the end the quickest shortest and best.

Buzz I can assure you I would never use less than 20 degrees out of that strip. I may have been the one to introduce the 10 degree flap position to this discussion. I used the 10 degree position to get a more positive rate of assent and maybe slightly less ground run than no flaps. And it is less drag than 20 degrees so I'd leave them in till I might be 1000 ft agl. I would not be trying to get of the ground quick and or clear a 50 ft obstacle.

In other words if I found myself hot high or heavy but had a long enough runway I'd use 10 because it was better than O and 20 was just to much for the accent profile I wanted.

If I didn't have the 10 degree position I'd have to get it. Because if you don't have it, you can't use it, but if you have it, you don't have to.

[Jr.CubBuilder]

That thread will be entitled 10 degree vs 20 degree flaps. Which one gets me out of a very bumpy 1200 ft strip with big trees a the end the quickest shortest and best. Note I'm screwed at this place if anything happens on takeoff. At reno I had 9000ft of runway. I could have lost the motor, landed, started it up, taken off, and repeated the cyle a few times.

My money would be on starting with 20 till the wheels leave the grass, then easing it down to 10 and climbing out with that. Of course I would practice this on a longer runway first

[c170b53]

Gee, thanks now I've got 10 degree notch envy.