Oil Cooler Info for 48 C-170

Jim Brann · Post by **Jim Brann** » Wed Dec 21, 2005 12:30 pm

Hi Tim, yes I do. There are four 12 1/2 gallon tanks all together. I don't know about being a better pilot, I think it might be more because of the greater surface area of the metalized wings and maybe a little more lift. Thanks for responding and best regards, Jim

zero.one.victor · Post by **zero.one.victor** » Wed Dec 21, 2005 6:28 pm

I wouldn't think that metalizing a ragwing would do anything plus or minus as far as lift is concerned. I do think it would add some weight.
The ragwing and the A/B wings are obviously different, the earlier wing is constant-chord ("hershey bar") and the later wings are tapered chord. I don't know which airfoils they use, or which one produces more lift. Maybe the same airfoil is used for both-- anybody know about this? I believe that the ragwing and the A&B all have the same amount of wing area, about 175 square feet.

Eric

Post by **Bruce Fenstermacher** » Wed Dec 21, 2005 6:38 pm

A popular belief among PA20-22 owners is that a metalized wing on their aircraft creates slightly more lift as the average airfoil is thicker than the fabric covered wing. This is because the fabric shrinks down in between ribs causing a thinner airfoil in those areas.

From what I recall this isn't so much the case on the 170 and so I'd expect the difference to be even less than the Piper products.

Jim Brann · Post by **Jim Brann** » Wed Dec 21, 2005 11:04 pm

I'm not sure about the technical data or the math that goes with all this, but I do know that my Dad has a 56 B model (N3525C) and I've flown both mine and his. I like his barn door flaps better than mine, but I can get off quicker, haul more of a load, and I can fly faster than him, with the same prop and same continental six cylinder engine. I see that the fabric wings were figured at 204 pounds and the metal wings 231 pounds, so it's and extra 27 pounds for the metal, I don't know about the lift. Also, My Dad always said that the straight 170 had straight wings, I'm not sure what is meant by that, I always thought that it meant that the wing went straight out from the cabin so it had no "V" shape at all. But my plane does have a slight "V" just like the B model, only the wing is straight across from the flaps out to the tips not swept back from the tips to the flaps like the "B". Anyway, that's all I know, best regards, Jim

Post by **Bruce Fenstermacher** » Thu Dec 22, 2005 1:20 am

Jim what your Dad probably meant is your plane has less dihedral than his B model. Or it's straighter.

Dihedral is the angle the wings are bent up at the tips when viewed from the front. If you look at an A model and a B model side by side you will see the difference easily. I'm not sure where your rag-wing stands comparatively.

A wing that is otherwise identical but has less dihedral will be more efficient at creating lift and therefor will fly with less angle of incidence and less drag than the wing with more dihedral. less angle of incidence equal less drag.

If you hang around here long enough you may pick up on some good natured ribbing between a fellow with a red B model and another with a Green A model. The difference in dihedral is supposed to be the major difference between the planes.

Earlier in this post someone referred to you wings as Hershey Bar shaped. That is in reference to the relatively rectangular shape of the wing when view from above. The A and B models have tapered wings meaning the tip is narrower in width (cord) that the root.

Your fabric wing really has little in common with the A or B model wing and will behave differently in the amount of lift and drag it will create. Even if it's metalized.

Jim Brann · Post by **Jim Brann** » Thu Dec 22, 2005 4:37 am

Hi Bruce, Thank you for the explanation, I have been a working man all my life like my father before me. My lack of formal training and education has caused me a lot of ribbing from my many stupid questions over the years. I appreciate your kind response without making me feel like a real dope. I'm learning little by little and I'll get there after a while. I bought my plane out of a field where it sat for over 11 years. I took it apart, stripped it, repaired everything I found broken or bad and when I started, I didn't know a bellcrank from a floating nut plate. After a year and a half, I put it back together and after getting over the wonder of getting it to run, I climbed in and wondered if it would fly. I have been told that I have more balls than brains and it's probably true, but it did fly and I am having the time of my life! I just love flying, and my plane is a poor man's machine, but it serves me well and I don't know if I'll ever get over just climbing in and lifting to the sky. Best regards and thanks for writing, Jim

Post by **Bruce Fenstermacher** » Thu Dec 22, 2005 2:47 pm

No problem Jim. I'm no aeronautical engineer but over the years of designing and building RC models and owning and maintaining 3 aircraft and flying helicopters for a living, I've learned a thing or two about aircraft and aerodynamics. And some of it I can remember and explain to someone else.

Don't worry about any lack of technical training here. Sounds like you have actual experience repairing and maintaining your airplane and that can't be said for many an aircraft owner.

zero.one.victor · Post by **zero.one.victor** » Fri Dec 23, 2005 1:55 am

Jim, I'm wondering if the reason your airplane gets off better, etc than your dad's might be just because it's lighter. You say the prop is the same, but I was gonna guess that maybe the prop pitch was different between them also. I do think that airplanes are individuals, your ragwing may outdo your dad's B model, while his B might kick my ragwing's butt.
Regarding dihedral, the rawing had 1 degree, the A model none, and the B model 3 degrees.
I've read alot about other airplanes and the airfoil used: as I recall the T-Craft used the 23012,Cub used the Clark Y , I've also heard of the USA 35. Don't know too much about the differences. But I have never read anything that referenced what airfoil(s) Cessna used on the 120/140, the rag 170, the 170A/B,or anything else. Deep dark trade secret, I guess. I would guess that the ragwing airfoil is maybe different from the 170A/B, but it seems logical to me that the ragwing used a bigger version of the same airfoil as the 120/140.But that's just a guess.Anybody have any information of this sort?

Eric

thammer · Post by **thammer** » Fri Dec 23, 2005 5:13 pm

The Historical Aviation Album drawings of the 120-140 show that an NACA 2412 was used for the wing and the NACA 0006 airfoil for the horzontal and vertical stabilizers.

I looked through the Paul Matt drawings I have and don't see that he did a 170.

tye

Post by **GAHorn** » Sat Dec 24, 2005 6:54 am

I believe it was stated in WD Thompsons book that the metal wing is a NACA 2412, and that it weighed 12 pounds LESS than the ragwing because it did not require internal bracing. (But I might have the weight thing as a memory item from elsewhere.)

auxtank · Post by **auxtank** » Fri Dec 30, 2005 10:55 pm

Eric said:

I have never read anything that referenced what airfoil(s) Cessna used on the 120/140, the rag 170, the 170A/B,or anything else. Deep dark trade secret, I guess. I would guess that the ragwing airfoil is maybe different from the 170A/B, but it seems logical to me that the ragwing used a bigger version of the same airfoil as the 120/140. But that's just a guess. Anybody have any information of this sort?

Eric, I found an Incomplete Guide to Airfoil Usage at:

http://www.ae.uiuc.edu/m-selig/ads/aircraft.html

Obviously, I cannot vouch for the information. However, the page is hosted by the Department of Aerospace Engineering at the University of Illinois at Urbana-Champaign.

The site gives airfoil usage for both the wing roots and wing tips of hundreds of models...including the Cessna line. Also, there are links at the top of the page to the websites of many of the individuals or agencies that have produced airfoil designs over the years, including NACA - the US National Advisory Committee for Aeronautics.

Bottom line, Cessna used/uses NACA 2412 almost exclusively for the wing root design of the C120 through the C207.

There was a link published recently in the forum for a site that has .pdf versions of Cessna parts manuals. If you check out the parts manuals for the C140 and the C170, you'll see the wings of those two models use many of the same ribs and other parts, including the wing root.

Gordon Sandy
Ragwing - N4002V

zero.one.victor · Post by **zero.one.victor** » Sat Dec 31, 2005 5:14 am

NACA 2412, great, thanks! Now we know.

Eric