Champ Control Surface Specs

gusc · Post by **gusc** » Sun Nov 02, 2008 21:04

I just checked all the control surface limits on my Champ. All were within specs except the Down Elevator which is 23*??

The book says this should be 15*. Is this correct? It sure looks normal at 23*.

I realize that an airplane doesn't need much down elevator and I don't see how this excess can lead to any harm but I would like to get it set at the proper amount.

Nathan K. Hammond · Post by **Nathan K. Hammond** » Sun Nov 02, 2008 21:21

How are you getting 50* of motion? Better check into that, or see if there's a math error somewhere.

That extra 10* can become a problem if you go full deflection at cruise speed or higher. The added negative G from the extra deflection could exceed the load envelope.

I know it's a far fetched possibility, but stranger things have happened and remember; you become a test pilot if the TCDS is not followed.

nkh

Post by **joea** » Sun Nov 02, 2008 23:53

Mine on the last two airplanes were within .5 of the TCDS and glad that they were. Set the limits as per the TCDS and enjoy the plane. More or less and you are not sure what you have.

Joe A

David Johnson · Post by **David Johnson** » Mon Nov 03, 2008 07:36

Don't forget all the bellcranks, cables, guides and such are all designed to work within the specs. If some nut gets ahold of it and shoves the stick under the dash over the top of some strange move and it sticks or binds it would be real bad. Major brown out...David J.

gusc · Post by **gusc** » Mon Nov 03, 2008 21:55

Nobody said if 15* is the correct number? I really want to verify if that is correct since all I have to go by is the Univair manual reprint.

Yep, that is the measured full movement all right! I was shocked to say the least. Needless to say I measured it a half dozen times!! It is pretty hard to misread the inclinometer since the tail is raised up to level the airframe.

It doesn't really look that gross just eyeballing it.

I don't really understand why the down stop bolt is not set to prevent that much but the bolt isn't even long enough to adjust that far. Obviously a new bolt and spacer are in order.

Additionally, today I found that the down cable is grossly slack so something is amiss in the whole system. That really got my attention.

The elevator cable system is so simple that there isn't much to go wrong. Now I'm beginning to suspect slipped nicopress fittings, that is scary. I know the cables were all new at the 2003 rebuild but I don't know the source of the cables.

Getting everything opened up is taking much longer than I expected for such a simple airplane, but this is my first time so next time will be a bit more organized, I hope.

Dennis · Post by **Dennis** » Mon Nov 03, 2008 22:13

Gus,

The following is from my 7AC Service Manual and my Buzz Wagner 0200 STC.

For the 7AC: the elevator travel limitations are 25* plus 0* minus 2* up, 15.5* plus 2* minus 2*down.

For my conversion to a CCM per the STC: the elevator travel limitations are changed to 24* plus 0* minus 2* up, 24* plus 2* minus 2*down.

There is also a change in the trim tab.

For the 7AC: Trim tab travel limitations are 20* plus 2* minus 0* up, 34.5* plus 2* minus 0*down.

For my conversion to a CCM per the STC: Trim tab travel limitations are changed to 17.5* plus 2* minus 0* up, 37.5* plus 2* minus 0*down.

The rudder does not change.

Maybe someone attempted to adjusted your elevator to CCM specs. I suspect there are other models which use the "greater" specs.

Dennis

gusc · Post by **gusc** » Mon Nov 03, 2008 23:04

Dennis,

You probably just solved the mystery! At one time it was a BCM, but only for a short time, so the change to a BCM must require the same elevator down setting as for a CCM.

That explains the short elevator stop bolt.

I suppose higher power pulls the nose up more but I never would have guessed it would make that much different.

It is still listed with the FAA as a BCM but has an A65-8 now.

It also had an A75-8 not too long ago!!

The really weird thing is that when I removed the baggage comp today a piece of paper fell out with all the control specs written by hand and it shows 15.5*??

Thanks.

Jody Wittmeyer · Post by **Jody Wittmeyer** » Tue Nov 04, 2008 10:22

Down is 15.5

Jody Wittmeyer · Post by **Jody Wittmeyer** » Tue Nov 04, 2008 10:40

The adjustments are inside the inspection panel in front of the rudder.
You get the tail up quicker with more down elevator. They are on a horn at the rear of the elevator

aeroncafan · Post by **aeroncafan** » Tue Nov 04, 2008 15:07

Gus, you're solving the problem all wrong...don't re-rig the airplane, put the bigger engine back on!

Now, if there just happened to be a nice C-85 sitting around your hangar somewhere???

If you find an extra one, I'd love one on my Champ too.

gusc · Post by **gusc** » Tue Nov 04, 2008 20:58

I checked the TD Sheets and the BCM elevator specs are the same as for the CCM. Dennis was right, that was the whole problem. When the A65 was reinstalled the elevator wasn't rerigged.

Easily solved with a longer bolt and spacer.

I'm one of these guys who loves the A65, it reminds me of a tractor engine.

I never lift the tail, I let it fly off when it's ready.

I also tightened the aileron cables from 20 lbs to 40 lbs and now the stick feels like it is in molasses? I oiled every hinge, pulley and the bell cranks but it made no difference. Any ideas on this?

It really is no problem but it seem quite stiff, not so much that it is too hard to move, but seems to have more friction than most I remember. I haven't flown one of these little guys in a long time so this may be normal.

gusc · Post by **gusc** » Thu Nov 06, 2008 20:01

My AI said yesterday during the Annual that the ailerons were too tight. I loosened the turnbuckle until he said they felt right. He said the cables would cut through the pulleys if left so tight.

Not surprisingly, I was back to the original tension of around 30 lbs. This was all done on the idler cable turnbuckle.

What is going on here? These cables must be misrouted too, otherwise why can I not get them up to the correct tension?

aeroncafan · Post by **aeroncafan** » Thu Nov 06, 2008 22:02

I've heard or read somewhere that the specs for aileron tension in the 7AC's manual (45-55 pounds in my copy) is way too high; same concerns your IA has. Can't remember who told me or where I read it though...anyone come across the same information?

t7275tr · Post by **t7275tr** » Thu Nov 06, 2008 23:40

I used to have an L16A. When we bought our 7AC it was difficult to bring the tail up on takeoff roll, compared to the L16. Checked the down travel on the elevator, it was correct for the 7AC, 15 degrees as I remember and reset it for L16 specs, 24 degrees . Tail now comes up with Billy Bob on the back seat but still can't climb like an L16.

gusc · Post by **gusc** » Sat Nov 08, 2008 22:27

t727,

When you use elevator to bring up the tail on takeoff you transfer the tail load to the main gear. Billy Bob in the rear just makes it worse.

In my opinion this increases the TO roll considerably. The tail will lighten as speed increases. Some TDs are so blind that you need to raise the tail but a Champ has such good visibility over the nose that this isn't necessary..

I've always let the airplane tell me when it is ready to fly and usually only need a tiny bit of forward pressure to keep the climb from being too steep if I don't have enough nose down trim.

A lot depends on where you have the elevator trim set before the TO roll starts. If you get it set just right the airplane will take off and climb at the proper angle without any elevator input at all.

National Aeronca Association Bulletin Board

Champ Control Surface Specs

Champ Control Surface Specs

Champ control surface specs