Wing Twist, Polishing Aluminum and the Disease

[GAHorn]

About two years ago I was assured (anecdotally) from Cessna Technical support that the C-170B wing was a direct development of the L-19/O1 wing, sans the hardpoints and flap system. Similar economies were utilized by using common tailfeather components. (Example: the elevator-tips are identical except that the right L-19 elevator-tip has the incorrect counterweight for a 170B, due to the difference between the two types trim-tabs. The rudder is identical except for the dual nav/formation tail lamp installation of the L-19. I've seen several 170's which have had their rudders replaced with L-19 rudders,...the giveaway being a blanking-strip installed in lieu of the lower nav-lamp holder.)
I've got a position letter from Cessna which a member kindly sent me, authorizing the replacement of 170 wings with any similar wing from a model of equal or higher gross weight. This would indicate/include 175, 180, 182 aircraft. There are sometimes differences which appear minor but that are in fact quite large, between the types. Example: fuel systems, fuel indicating systems, flap operation and flap cable routing, etc., etc.. But the basic wing is the same, at least in the early models. Later, changes were made in leading edges, etc.
(Going the reverse direction is not in the cards however. Structural components are in some cases lighter/thinner in the lower gross-weight types.)

[zero.one.victor]

I've never heard of a Bird Dog with manual flaps, I believe they're all electric. This seems kinda unusual to me, for a non-complex airplane designed around 1951. And undesirable, I'd much prefer a Johnson bar.
But I like the 60 degrees!

Eric

[N2218B]

We have three bird dogs here on the field. The two I have flown had manual flaps. I have ridden in the third one which has electric flaps and a constant speed prop. I believe I was told it is an E model. I don't know enough about them to say what model has what. If I think about it I'll ask one of the local owners when the switch was made to electric.

[zero.one.victor]

I'm learning a lot about Bird Dogs here for a 170 forum! Great!

[170C]

I have very little actual knowledge of the technical items of an L-19. They are, from what I have observed from the ground and been told by pilots, a heck of a performing plane. As most have seen at flyins, etc, they can be really good looking too. I have been told by more than one owner that their L-19 orginally had manual flaps, but had been converted to electric ones. Regarding which is best probably depends upon the pilot and his likes & dislikes. Would be nice to have one. Two place with limited baggage room, but I'd make the sacrifice!

I know there are some (don't know how many) members with L-19's. Maybe they can add a bunch to this discussion. I remember one at the convention in Tehachapi this past summer.

[Metal Master]

I have been following this thread with some interest as well. I have had the opportunity to look at a couple O-1's in the recent past and even worked on one in the US ARMY trade school at fort Eustis Virginia Airframe school back in 1971 before going to Viet-Nam. The instructors used to punch holes in it that we would have to make parts for and then patch. It is most heart wrenching to think about now. I have always coveted these airplanes and had always made some assumptions that I now realize were wrong. I did learn a lot while in the school and have always appriciated the oportunity. I now wish I had been able to go to more of the training sections the ARMY had at Ft. Eustis. The training was much better than any A&P school that I have had experiance with.
· I thought they had the same type of flap that the Cessna 170B has but that they went down to 60 degrees. They do not. They are hinged flaps like the 170 A that go to 60 degrees.
· I thought they all had manual flaps. The earlier models do the latest models had electric.
I went on line to try and find some pictures of the flaps to confirm what I now believe to be true as stated above which I would not claim to be the facts. But what is interesting is that there is an International Bird Dog Association much like the 170 Association. I spent two hours yesterday morning reviewing there maintenance section on the web sight which has some things that would be pertinent to Cessna 170’s and there owners. There are some nice pictures of restored Bird Dogs as well as some good insights to be gleaned on the web sight. Here is the web address:
http://www.l-19bowwow.com/toc.htm

[blueldr]

Be advised that the hinged flaps on the L-19 (O-1) and the hinged flaps on the C-170A have absolutely no similarity to each other except that they're pivoted on a point rather than trailed on a track. The A model has a split type flap on the under side of the wing whereas the L-19 has a flap very similar to the B model in that the whole trailing edge pivots back and down.

[n2582d]

I built a 100 series wing jig years ago from plans I purchased out of Trade-A-Plane.

I'm in the process of building a wing jig but have some questions. The three degrees of washout--does the axis of that twist rotate around the front spar or some point in back of it like half way between the front and rear spar? It's probably a moot point (assuming the twist is correct) as the wing will be put in the jig before I start drilling out rivets. Do your wing jig plans duplicate Cessna's jig? Any chance of buying a copy of those plans?