Aileron spar lightening holes

[GAHorn]

Thanks, Del. That was what I meant when I said the two models wings were the same.... I meant there was no twist inboard of the strut...and except for flaps they were essentially the same....the twist differences occur outboard of the upper strut attach.

My comments regarding the half-inch difference at wingtips between ailerons and tip-fairings are merely repetition of the official Cessna rigging instructions. I doubt very many of these older airplanes have their original, unrepaired ailerons and/or their original riggings unchanged, therefore I am suspicious of any claims that an existing airplane or existing 50-year-old aileron is still in original alignment.

(We certainly know that MY airplane, despite my slogan, isn't original in that regard.)

[jatkins]

My 1952 C 170B serial # 20292, has 27 holes in the aileron spars.
My wings have been , changed ( by me ) but as far as the records slow not the ailerons.

[ginbug92b]

My 1955B serial 26836 8 hole ailerons both sides

[wingnut]

Thanks, Del. That was what I meant when I said the two models wings were the same.... I meant there was no twist inboard of the strut...and except for flaps they were essentially the same....the twist differences occur outboard of the upper strut attach.

My comments regarding the half-inch difference at wingtips between ailerons and tip-fairings are merely repetition of the official Cessna rigging instructions. I doubt very many of these older airplanes have their original, unrepaired ailerons and/or their original riggings unchanged, therefore I am suspicious of any claims that an existing airplane or existing 50-year-old aileron is still in original alignment.

(We certainly know that MY airplane, despite my slogan, isn't original in that regard.)

I knew what you meant. I just thought it may have been confusing to others, and wanted to clarify what I had previously said, because what I said was not detailed enough.
We both know that trailing edges lining up perfect rarely affects how an aircraft flys, but wing twist (washout) does because of the surface area involved, a small difference makes a big difference in flight characteristics, versus the smaller surface areas of control surfaces.

[johneeb]

Del,
What is involved in taking a set of Ailerons that do not match up at the wing tip end and correct the alignment?

[wingnut]

Del,
What is involved in taking a set of Ailerons that do not match up at the wing tip end and correct the alignment?

Wow, That's a BIG question.
It would depend upon MANY factors, and I can't answer that with a simple reply.
Most control surface alignments (trailing edge alignment) does not affect flight characteritics.

George is completely correct when he mentioned the aileron " droop". That is typical of factory specifications. However, that does not mean that is right. I have found that when an aircraft is rigged right, it doesn't matter if those trailing edges line up perfect. What does matter is if the entire system is rigged correctly

If you are asking what it would take to align your flight control trailing edges, I would ask if you have a flight rigging problem? It would be impossible for me to dertermine your problem without more infomation.

If you are concerned about the cosmetic appearance of your aircraft , we (me and you) can maybe do sonething about that, but I have to see the problem.

Give me more info please

[johneeb]

If you are asking what it would take to align your flight control trailing edges, I would ask if you have a flight rigging problem? It would be impossible for me to dertermine your problem without more infomation.

If you are concerned about the cosmetic appearance of your aircraft , we (me and you) can maybe do sonething about that, but I have to see the problem.

Give me more info please

Del,
Concern about the cosmetic appearance is right on, the rig is fine, the miss match at the wing tips keeps me awake at night. I recall reading one of your earlier posts that when you rebuild an aileron you leave out the last several trailing edge rivets to accommodate aligning the end of the aileron with the wing tip. If I am recalling correctly can this process be followed retroactively?

[Bruce Fenstermacher]

John, what are you trying to do. Change that last half SUV decal on your cowling to a full one?

I suggest you invest in some sheep to count at night rather than tear into your plane.

What Del doesn't know is that your plane won "Peoples Choice" this year at the convention. And had you been able to have your plane at the convention for the required judging period it would have been in the running for "Best Custom" as well.

Bottom line you have a very nice plane. As a judge I'm not given you any more points if your ailerons match the wing tips.

[c170b53]

You might make something more pleasing to the eye but in fact it may not accomplish what you think the outcome will be. As an example you would think that a smooth surfaced golf ball would look better and perform better than one with all those dimples (and those balls don't help my game either). I doubt that there would be a measurable improvement or degradation in performance if you altered the ailerons.

[wingnut]

If you are asking what it would take to align your flight control trailing edges, I would ask if you have a flight rigging problem? It would be impossible for me to dertermine your problem without more infomation.

If you are concerned about the cosmetic appearance of your aircraft , we (me and you) can maybe do sonething about that, but I have to see the problem.

Give me more info please

Del,
Concern about the cosmetic appearance is right on, the rig is fine, the miss match at the wing tips keeps me awake at night. I recall reading one of your earlier posts that when you rebuild an aileron you leave out the last several trailing edge rivets to accommodate aligning the end of the aileron with the wing tip. If I am recalling correctly can this process be followed retroactively?

Yes, it can be corrected on wing, but I am hesitant to recommend doing it because you do not have a rigging problem and I'm guessing you don't need an aileron reskin for any other reason. If the droop is equal on both sides, and as George says "approx 1/2 inch", I would except that as a common situation. As I said before, perfect alignment is probably the exception rather than the rule.
If you insist on perfect alignment, we can do it.

[GAHorn]

I will "chime in" on this and remark that if your ailerons are equally-disposed on both sides and within 1/2" of the tip fairing....to leave well-enough alone. If, on the other hand you just HAVE to see them aligned perfectly with the wingtips.... Del can probably take care of that. (I don't want to say what it wil cost, that's his job.... but I'll bet you'll be very pleased.)

Let me give you an example: My own airplane. My flaps were poorly re-skinned during it's previous reconstruction. They both had "twist", trailing-edge-upward in a left-to-right direction....exactly the same. The result was that even tho' the airplane flew perfectly well, (they were equally wrong on both sides) my ailerons BOTH perfectly matched my wingtip fairings (just as you seem to desire).... and my right flap matched the aileron....BUT.... the right flap was about 1.5" below the shoulder-fairing at the fuselage, while my left flap exactly matched the shoulder-fairing...with the left flap 1.5" below the left aileron.

Like yourself, it kept me awake at nights despite the fact my airplane has won "Best Original" when it was submitted for judging at Las Vegas and Wilmington. It drove me nuts, yet the airplane flew perfectly level, hands off, and faster than any green 170. (He's up there laughing.)

I took it to Del. In two days he removed my flaps, drilled off the upper skins and placed the flaps in his flap-jig and re-rivetted the upper skins. He then re-rigged my ailerons/bellcrank/actuator-rods and now my flap/aileron alignment is as Cessna intended it. The flaps match equally at the fuselage and at the ailerons...with the ailerons 1/2" below the wingtip fairings. Del only had to adjust my right eccentric bushing slightly after one test flight. The next flight confirmed his correctness. He and Tony worked past closing the first night in order to assure my planned departure time, but as promised, he had me off-and-flying in two days and he more than met all expectations.

[170C]

With all the posts on this subject, I had to check mine to see what it has. My '56 172 ailerons both have 8 lightening holes in the spar. Gee, I can't imagine why one would have 27 holes. That would either make for a very light spar or a weak one I can't speak with authority, but I suspect the early 172 ailerons, flaps, wings, and most of the fugelage are identical to the late model 170's. My ailerons are about 1/4" - 1/2" below the wing tip (the fiberglass wing tips), they line up with the flaps and both flaps are about the same drop of 1/4" - 1/2" inch below the fairing at the fugelage. With the air passing under the flaps (in flight) they come up even with the fairing. I don't know if this is normal or good or whatever. Fortunately in smooth air, with the plane trimmed, there is no tendency for the plane to wonder off left or right. In that situation one can sit there with feet on the floor & arms folded---almost like an autopilot, BUT--wiggle in the seat, lean forward or any other movement and the stability is upset to varing degrees. Trouble is there isn't too much of that kind of conditions in day-to-day flying. OH FOR A 3 axis AP.

[voorheesh]

I was looking at a late model Cessna 172 that I rent at work and the ailerons do not ine up with the wing tips. They line up with the flaps ok but they are both slightly lower than the outboard edge. My 170A (ailerons have been pronounced airworthy but have seen better days) has madras droop down wing tips and left aileron is about 1/2 " below the left wing tip and right aileron is less than 1/4" above the right wing tip. The airplane flies very well hands off. I wonder if it really matters.

[GAHorn]

With all the posts on this subject, I had to check mine to see what it has. My '56 172 ailerons both have 8 lightening holes in the spar. Gee, I can't imagine why one would have 27 holes. That would either make for a very light spar or a weak one I can't speak with authority, but I suspect the early 172 ailerons, flaps, wings, and most of the fugelage are identical to the late model 170's. My ailerons are about 1/4" - 1/2" below the wing tip (the fiberglass wing tips), they line up with the flaps and both flaps are about the same drop of 1/4" - 1/2" inch below the fairing at the fugelage. With the air passing under the flaps (in flight) they come up even with the fairing. I don't know if this is normal or good or whatever. Fortunately in smooth air, with the plane trimmed, there is no tendency for the plane to wonder off left or right. In that situation one can sit there with feet on the floor & arms folded---almost like an autopilot, BUT--wiggle in the seat, lean forward or any other movement and the stability is upset to varing degrees. Trouble is there isn't too much of that kind of conditions in day-to-day flying. OH FOR A 3 axis AP.

The lightening holes do not weaken the spar or the aileron. They decrease unnecessary weight. The later, 8-hole spars reduce labor costs, while adding weight.
It sounds as if your flaps/ailerons/tips are correctly aligned. Its fine for the flaps to be slightly below the fuselage fairings when at rest. (As you noted they likely align in-flight.)

I rarely wiggle in my seat when I'm asleep, so I don't need an autopilot. But you can get one installed up at Mineral Wells for about $16K if you like. (It amuses me to think we all spend a ton of money to pursue our dreams and hobby of flying airplanes....then complain that we must do so manually.)

[flyguy]

I will "chime in" The flaps match equally at the fuselage and at the ailerons...with the ailerons 1/2" below the wingtip fairings. ---------------- - - - Del only had to adjust my right eccentric bushing slightly after one test flight. The next flight confirmed his correctness. He and Tony worked past closing the first night in order to assure my planned departure time, but as promised, he had me off-and-flying in two days and he more than met all expectations.

EVER TING LOOK GOOD SO WESA TAKE OFF TO LOOSYANA COME INNA TOLEDO BEND INNERNACHINAL AIRTSTRIP AN DEN DE FLOPPY FLAP HANEL BROKE INSIDE, GEORGE 8 SOME BEAN AN BACON WIT ME AN DEENIE DEN WANT ME TO GIDE HIM BACK TO MEENA BUTS I GOTS TOO MEENY TINGS WAITIN ON ME SO DINT GO. HE FINE IT OK BY HISSELF AN NAOW HE GOTS A MODIFY FLAP HANEL AN 4 NOTCH PAUL PLATE IF IT AINT 1 TING ITSA NUTHER 5 TINGS