High altitude t/o with stock 170

[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.

[GAHorn]

Back to the original question.
What gives you the shortest takeoff roll....

That was not the original question. Here's the original question:

Wondering what the wisdom is for a stock 170 takeoff at high density altitudes. ....

(Just keeping an eye on you, Buzz....as I know you do on me.)

Bottom line of this discussion is still:
Flaps hurt any climb toward clearing obstacles...regardless of whether they are used during takeoff roll or during initial climb...and even if they are reduced from 20 to 10 degrees after lift-off (in fact, that is an even WORSE performance situation. Flaps, if deployed, should not be retracted until AFTER obstacle clearance or you will have had the worst of all possibilities.)
Flaps will increase total takeoff distance (brake release to obstacle) an inordinate amount at high density altitudes. Cessna has used new airplanes and professional test pilots to determine and document that.

[Jr.CubBuilder]

Flaps will increase total takeoff distance (brake release to obstacle) an inordinate amount at high density altitudes. Cessna has used new airplanes and professional test pilots to determine and document that.

You are right George.....of course.....except for situations in which the runway surface creates enough drag as to prolong (in some cases indefinitely) the part of the takeoff during which the undercarriage is in contact with the grass, snow, or water. In these exceptions the surface drag can, and will, extend the takeoff. Flaps can be used to lift the plane into ground effect, and more acceleration can then be obtained while the flaps are slowly retracted. This technique isn't in the book, but it can be advantageous in some situations.

[buzzlatka]

I think I narrowed or clarified my question in the second post to include just distance.

Anyway I don't want to get into an argument with George because he will probably win and he is to valuable as my personal online 170 maintenance adviser.

I agree completely with jrcubbuilder on the flaps point. I did some testing on rough grass with the flaps/ no flaps and the "pull the flaps just prior to takeoff" methods. I found that having the flaps at 20 on initial roll got me lighter on the gear (reducing the surface drage) and I accelerated quicker.

I should have flaps 10 installed during the october annual. No more flap envy.

[GAHorn]

[...except for situations in which the runway surface creates enough drag as to prolong (in some cases indefinitely) the part of the takeoff during which the undercarriage is in contact with the grass, snow, or water. In these exceptions the surface drag can, and will, extend the takeoff. Flaps can be used to lift the plane into ground effect, and more acceleration can then be obtained while the flaps are slowly retracted. This technique isn't in the book, but it can be advantageous in some situations.

YES... I agree...and perhaps that is the real variable in this conversation. It's difficult sometimes to accurately convey the finer points of discussion on-line. We may all realize the same thing...yet think we are disagreeing when we really aren't.

Buzz...I never (or rarely) think of these discussions as real "arguments". It's difficult to remember that with the online-written-word sometimes, I guess. I know you're not arguing...and I hope no one thinks I am either. (Although, an argument...should not be a problem for friends anyway. I think that word has achieved increased meaning-of-furor in recent decades. To "argue" a point used to mean simply describing the advantages/disadvantages of differing viewpoints...but recently has come to include instances of loss-of-temper.) I certainly never think of you in that latter definition.

[cessna170bdriver]

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.

Buzz,

If you want do some hands-on evaluation of 10 vs 20 degree flap settings before committing to modifying yours, you're welcome to come down to Tehachapi and give my '55 a try. You can also compare a range of altitudes, as we're at 4000ft with 6-7000 ft density altitude this time of year, and Bakersfield Muni is under 400ft, only 20 minutes away.

[GAHorn]

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.

Buzz,

If you want do some hands-on evaluation of 10 vs 20 degree flap settings before committing to modifying yours, you're welcome to come down to Tehachapi and give my '55 a try. You can also compare a range of altitudes, as we're at 4000ft with 6-7000 ft density altitude this time of year, and Bakersfield Muni is under 400ft, only 20 minutes away.

You can also simply place a book or brick under your flap handle with it deployed to the ten-degree position.

[cessna170bdriver]

You can also simply place a book or brick under your flap handle with it deployed to the ten-degree position.

George, you're such a killjoy! Your suggestion does nothing to help me put faces with names on this forum.

[GAHorn]

Sorry about that. Maybe he'll bring a few books to place under YOUR flap handle to find which one will calibrate the ten degree position?

[runerider]

What is the hand dance on a go-around, is that let go of the flap handle grab the throttle all before the flaps go to zero or do you have a friction lock on your flap handle?

[n2582d]

I was just looking at the AFM for the C-170B in the documents section of the Maintenance Library. All you guys with the 10 degree notch have got to quit using it! It is not listed in that document as the document was written for the early C-170B which didn't have the 10 degree notch. Is there a later version of the C-170B AFM? If so, maybe someone could e-mail Bruce a copy of this later C-170B AFM for inclusion in these documents.

Thanks Bruce for starting that documents section, it's invaluable for those of us with incomplete documentation. I've sent some Javelin aux fuel tank documents to your gmail address to be added to that section.

[Bruce Fenstermacher]

Gary,

That section is just gettng started. Those are the things I could quickly think to put there.

I (as well as George I'm sure) have been collecting stuff when I find it. George of course put some of it in the MX area and we've got stuff all over. George and I also have our associations 337 library which has been scanned but in need of reorganizing and cleaning. This is a project I started a few years back. I'll be placing the 337s and stuff as I can find the time to go through each piece.

There are lots of things we could use. A later B model AFM would be welcome and anything else. I've actually got older versions of the AFM for the A and 48 but didn't post them as they aren't current and really only interesting for historical value. I'll probably post them somewhere eventually.

The Owners Manual we have for the 56 could be much better. Anyone have a good one I can scan? Also looking for earlier B mode owners manuals. The one I have Cessna did later which combined the 52-55 models into one, is copyrighted by Cessna. I elected not to post that. But earlier individual years won't be copyrighted.