Turning radius

[54170b]

I was talking to an old pilot. We were talking about extra fuel options for a cessna 170B. The subject of installing 175 wings on the airplane came up, and he said: "If you install 175 wings onto a cessna 170b, the turning rtadius will be much wider than a normal 170b, witch turns well inside a cessna 175. the turning radius wioll be that of a 175 because of the 175 wings, because of the diehedral."
Is there any truth to this atall? I always thought they were the same slick wing, with extra metal, and a larger fuel tank. (old enough to have manual flaps)
The reason I was talking to him about this, is because my wings ned to be rebuilt, and there are some 175 wings that I know of that could be for sale at a good price. I was also wondering if anybody knows where the 337 or stc is. If the turning radiuse is messed up by this, I wouldent do it for sure.
Also would it just be the 175 wing strut compaired to the 170b strut that changes the turning radius? thanks- Kyle
(there will be a sportsman stol kit on this airplane, and there might be micro vgs)

[bagarre]

I don't fly inside canyons much and I rarely dogfight in my 170. Where would a larger turning radius be such an issue?

I was taught that speed and weight (thus, G force) impacts turning radius the most.
Could he be referring to the greater quantity of fuel (thus weight) the 175 wings can carry?

[54170b]

Because im going on floats, and tighter is always better. He is referring to the difference in diehedral in the 170/175 wings.

[runerider]

I might be having a senior moment, but turning radius is turns on the ground taxying. Which a tail wheel would turn in a tighter circle. Is the wing span of a 175 greater than that of a 170? On floats it shouldn't make any difference.

[54170b]

To clairify, The turn in the air.

[Robert Eilers]

I have always understood that speed and weight had the greatest affect on turning radius. I find it hard to believe the 175 wing would result in a significantly greater turn radius. The addition of the STOL kit and VGs you mentioned will contribute positively to a short turn radius. There is a good discussion of turn radius in the link below.

http://www.canyonflying.com/canyonturns.html

[runerider]

excellent book for lite reading. FLY THE WING for Naval aviators.

[Bruce Fenstermacher]

The 175 wing and the 170B (and the 172 and the L-19) wing are the same other than gas tanks and of course there is probably different structure. You would use the 170B struts which set the dihedral. I'll bet the 175 struts are the same in length anyway and would set the same dihedral.

Besides being able to carry more gas you wouldn't know which wings you had. Besides the added gas, there is no benefit or shortcoming to the modification. In short you either missunderstood the old timer or he didn't know what he was talking about.

If you read any of several threads on the forum about installing 175 wings you will find out there is no STC available for you to use to install 175 wings. In the old days this was done it seems with no real thought. That was the old days. There have been reports of folks having difficulty getting the FAA to approve this change but there have been reports of folks with recent success as well.

[54170b]

I sent a pm to "velvet" he told me to talk to headquarters about getting a 337

[blueldr]

This thread is becomming ridiculous!

[minton]

I was talking to an old pilot. We were talking about extra fuel options for a cessna 170B. The subject of installing 175 wings on the airplane came up, and he said: "If you install 175 wings onto a cessna 170b, the turning rtadius will be much wider than a normal 170b, witch turns well inside a cessna 175. the turning radius wioll be that of a 175 because of the 175 wings, because of the diehedral."
Is there any truth to this atall? I always thought they were the same slick wing, with extra metal, and a larger fuel tank. (old enough to have manual flaps)
The reason I was talking to him about this, is because my wings ned to be rebuilt, and there are some 175 wings that I know of that could be for sale at a good price. I was also wondering if anybody knows where the 337 or stc is. If the turning radiuse is messed up by this, I wouldent do it for sure.
Also would it just be the 175 wing strut compaired to the 170b strut that changes the turning radius? thanks- Kyle
(there will be a sportsman stol kit on this airplane, and there might be micro vgs)

Who the heck told you that?? Cessna has always tried their best to keep it simple. Same wing airfoil design from 170B through 185. Wing struts the same length 170B through 185. The STOL kit and VG's have to be evaluated as to their collective impacts on the wing performance. Stay away from "Flap Gap Seals" if you go the STOL route.

Just my humble opinion

[minton]

Read A/C 23-27 With that and someones completed (approved) paperwork package as a basis it can be done without much hastle. The wings will cost you some $$$ and you must address the C-175 fuel quantity indication, (Mechanical 170B vs 175 Electric) also fuel tank venting is different but EZ to overcome.

[minton]

This thread is becomming ridiculous!

Dick,
I agree. I thought that part of pilot training was afoil design vs performance.

[Bruce Fenstermacher]

I sent a pm to "velvet" he told me to talk to headquarters about getting a 337

Headquarters does have one or two completed 337s covering the approval of 175 wings. These were done in the days of old when knights were bold. The 337s have no detail and other than showing that at one time a representative of the FAA thought the change was OK, which might be of interest if you are counting those numbers, today their barely worth the paper they might be printed on. Don't waste your time thinking they will be of any help.

The subject of field approvals is often debated, and little understood by most. Because in my opinion today very few jump through the hoops, or perceived hoops, to get a field approval. Most mechanics will usually shrug their shoulders and say it is impossible to get a field approval and won't want anything to do with it. This probably comes down to money. It is easier and a safer bet to get paid for something you know you successfully complete, like an oil change, than it is to get paid for a project that may not ever be completed due to regulatory requirements.

Kyle. Minton is pointing you to all the information you need. AC 23-27 Parts and Materials Substitution for Vintage Aircraft describes the procedures need to qualify the 175 wings for the 170B wings. Then following AC 43-210 - Standardized Procedures for Requesting Field Approval of Data, Major Alterations, and Repairs, you would request a field approval.

What he is saying about a persons completed approved package is this. There are people who have jumped through the hoops and have, at their expense, gathered all the necessary documentation. This documentation will obviously have some value to those that want to do the same thing. So with their documentation, which you likely will have to pay for, following the procedures in AC 23-27 and the field approval process in AC 43-210 you should also be successful receiving your own field approval. You wouldn't have to use their "package" you at your expense can develop your own.

It would seem to me that unless there was a reason to use the 175 wings, like the additional fuel, that you could probably repair your 170B wings cheaper than getting the 175 wings approved and therefor that would be the best way to go. But it would be very educational for you to investigate each avenue and decide for yourself.

[KG]

Getting back to the original question.....
Turn radius, if you are talking about a track across the ground as if you are in a canyon, is a function of the ground speed. Doesn't matter if you are flying a cub or a Learjet. Fly fast and you will have a wide turn. Fly slow and your turn will be tighter. Turn into the wind and your groundspeed is reduced, thereby keeping the turn tight. Turn downwind and your turn will eat up more real estate. Dihedral has nutton to do with it (other than some wing designs will allow flight at a slower speed, i.e. the cub vs. the Lear).