There is one other possibility. You may have a Frankenbird. When they did the off books repair, they may have substituted some parts from other aircraft, like the stabilizer. A quick glance at my parts book, which only goes back to 1961, shows a different part number for early stabs. You may actually have the wrong stab or elevators. I don't know, without looking at two side by side if the forward or rear attach brackets are not of different sizes on early ones. Or they may have changed the brackets and used the incorrect parts, or finally there is the rear pivot for the stab. It does get wallowed out and sometimes it is replaced or bushed. If it is not located correctly, well you see where this goes.

Thanks dog. Even if it were a different model stab or horizontal I dont think it would weigh 30+ lbs more. The 185tail doesnt even weigh that much more. And even if it we're not aligned right; which I'm pretty sure it is; it would definetly change the flying characteristics, but not the actual weight. I have my 56 in pieces to compare to and so far nothing seems crazy. And i did put the elevators of my 56 onto the 55 since they were in better shape. I wasn't able to make it back out this afternoon like I thought so hopefully tomorrow after work.

I tried to read all your post 55 but may have missed something. Rigging, Have the book out and another mechanic double check it. W/B, you only weighed the tail and still to have questions. Do a real weight and balance on the mains and tail. (I would say only un-usable fuel) + or - 10 lbs at that arm is a big moment. A buddy of mine still cant find his hammer. The STOL mods wont do this.

Did you weight it with the tail elevated and a level on the door frame? If not that 150lbs may be inaccurate. An extra 50lbs (from rob's control specimen) that far out on an arm is significant.

This is an interesting mystery (sorry your bird is at the center of it.)

I have service and parts manuals in PDF I could email to you if you want them.

You stated in a previous post that the tail is slow to come up, Forward trim lifts the front of the stab, so... Either it is rigged with the front of the horizontal stabilizer way too low, (most likely) or there is a gold brick back there that you haven't found. The weight sounds reasonable to me though.

Checked my 55 and tail weight at recent weighing was 117 lbs, overall weight was 1736 (wing-x, sportsman, float kit, R engine, aux tanks...). If I calculate what tail weight would be with 50 gallons fuel as you said, I get right at 150 lbs. So your tail weight doesn't sound like the issue to me.

My trim behaves normally, just a little nose heavy. Have to hold a little back pressure when slow on short final, even with full nose up trim. At 50 mph, the negative lift of the tail is a bit weaker relative to the higher lift of the larger wing with wing-x and sportsman, and so I run out of trim, or so goes my theory. I've thought about tail VGs to get more (negative) tail lift. But anyway, I don't think the STOL kits are the issue either based on my own experience.

Yours just seems backward...

Zzz wrote:Did you weight it with the tail elevated and a level on the door frame? If not that 150lbs may be inaccurate. An extra 50lbs (from rob's control specimen) that far out on an arm is significant.

This is an interesting mystery (sorry your bird is at the center of it.)

It is interesting.....

If I read his earlier post correctly the quoted weight was with 50 gals of fuel. Gas sits at +48, tailwheel at +260. Therefore assuming a hinge point 14" behind the firewall where the datum is, the gas would have a net effect of approx 41 pounds at the tailwheel. I looked and couldn't find the station for the ground contact point for the forward swept gear, but it is I'm guessing say 14 inches behind the firewall. If someone has that handy we can calc it pretty accurately. Anyways, what's in the plane when you weigh it makes a significant difference.

Rob's 53 with the straight leg gear is light because the mains are farther back. It doesn't take moving the balance point much to lighten the tail considerably..... You have that 400+ pound engine hanging on a longer moment arm. You can't really use Rob's plane as a reference in this case.

55, you might think the tail weight I mentioned was heavy, turns out it was higher than I remembered. Took a look at the recorded weights. With full fuel and tools/spares/survival kit stuff in baggage it was 164#. I wasn't there the day they weighed it and had some other concerns about the procedure they followed, like not removing all of the extraneous stuff. They may have left the tail down. I tossed the W&B data because there were too many uncertainties.

All I am saying is the 150# with 50 gals of fuel is definitely in a reasonable range. My plane runs out of nose up trim in 3 point in all but very aft CG scenario, and the tail flies at 25-30 kts with full baggage. Go figure.

Also, make sure you have a copy of the TCDS when checking the rigging. The older 180's have a larger "up" angle on the stabilizer of 1.5 deg versus the 0.75 deg quoted herein for the later models.

Good luck with figuring this all out. I still can't fathom what would cause a condition where a wing would need less nose down trim at higher speed than it does in slow flight. That defies all aerodynamic theory I bothered to learn.

Flynengr

Skyjeep and others with not enought nose up trim. The tail doesnt run out of lift because the increase in lift by the wing with the Sportsman and Wing-X. You are probably flying 10mph slower than before, reducing the lift (down force) of the horizontal. I tried my own VG design on the bottom of the small horizontal on my 63 182 Sportsman to increase slow speed pitch authority when fwd CG. I didnt get the result I wanted. #50 tool box strapped to the O2 rack worked great and was my best result.

Terry. That would be great man! I'll pm you my email and if you have time that would be greatly appreciated.

oldtech. the trim is tapped out hitting the stop. Theres nowhere else for it to go..

skyjeep. The crazy thing is is that it behaves pretty normal with zero in the back and two front seaters. seems to fly a little more trim forward than should but slow flight and landing its trimmed way back. not all the way back but a good ways.. I do have vgs on wings and tail to.

flynengr. Thanks for those weights. If its not to far out on the weight then I definetly have a problem thats way over my head because the tail seems completely right and working properly. I have about 5 inches of travel from top to bottom in the trim range. That seem right? Has to be some type of rigging, bent, or twisted problem I guess. I have been looking in every nook and cranny from the backseats to the tail looking for extra weight. Nada.
I cant figure out either what in the world would make it act like it does. full forward trim until I get it up to around 100 indicated. from there up i can start trimming back a little. level flight 140-145 indicated mph it rides about halfway between normal level flight and full trim forward. when i slow down it gets a little tail light until about the 100 mark and then start trimming forward the slower i get till full forward. Landing with full flaps requires full forward trim and a bit of forward elevator. touching down a little faster than i like as soon as i release the pressure the tail falls out. It "feels" really heavy.

Thank all of you for taking the time to help. I cant get over the amount of help everyone has been. really awesome.

55wagon wrote:Thanks dog. Even if it were a different model stab or horizontal I dont think it would weigh 30+ lbs more. The 185tail doesnt even weigh that much more. And even if it we're not aligned right; which I'm pretty sure it is; it would definetly change the flying characteristics, but not the actual weight. I have my 56 in pieces to compare to and so far nothing seems crazy. And i did put the elevators of my 56 onto the 55 since they were in better shape. I wasn't able to make it back out this afternoon like I thought so hopefully tomorrow after work.

You're right about the weight but the required angle of incidence may be slightly different. Somebody said the tailwheel is at 260", at that distance an incidence error of 1/8" would make quite a difference.

Check you engine mounts. Is it possible that the mount is tweaked, or broken allowing a variable thrust line? It does not take much movement in the engine to really hose up the thrust line and make trimming impossible as your chasing it with trim and various power settings. Just a WAG since you seem so certain that the trim is getting full range of movement.

Someone correct me but you have 2 Hoz trim jack screws, Chain against gears on the jack screws. Is the chain the stop at the cable or what is the stop at the horizontal? The initial jack screw setting controls the pitch of the horizontal to the waterline? I have rebuilt those systems but it has been a while. Do you have the maint manual? You state Forward / back trim. You mean Nose down / up trim?
AKavid, I think you may be on to something. From his description power seems to have an affect on his pitch. Maybe that is why I was having a hard time following his description.

Forward trim meaning nose down.
My motor mount is new. But possible it could be off at the firewall?? I noticed it seems the like the prop, or motor, appears to ride high in the cowling. Could just be how it lines up tho. Where would I take a measurement to check that?
Ill be looking for a good rigging guy and one who can check all these things if anybody knows of any. Hopefully not a terrible distance away. Remember hearing about a guy in Dallas area that's supposed to be excellent but can't remember who.

just got off the phone with john efinger up at hicks in dallas. supposed to be a cessna rigging expert. he can see me in about 2 months!!

Oops. Posted too late. Looks like you already contacted John.

Flynengr

akavidflyer wrote:Check you engine mounts. Is it possible that the mount is tweaked, or broken allowing a variable thrust line? It does not take much movement in the engine to really hose up the thrust line and make trimming impossible as your chasing it with trim and various power settings. Just a WAG since you seem so certain that the trim is getting full range of movement.

This is a good lead. You'd think enough movement/displacement to affect thrustline would be obvious, as the crack would have to be pretty bad; there'd be vibration like mad. Maybe not with a crumbled/collapsed Lord mount. Maybe it's not a failure at all, but a poor installation on the "new" motor mount.

flynengr wrote:

Zzz wrote:Did you weight it with the tail elevated and a level on the door frame? If not that 150lbs may be inaccurate. An extra 50lbs (from rob's control specimen) that far out on an arm is significant.

This is an interesting mystery (sorry your bird is at the center of it.)

It is interesting.....

If I read his earlier post correctly the quoted weight was with 50 gals of fuel. Gas sits at +48, tailwheel at +260. Therefore assuming a hinge point 14" behind the firewall where the datum is, the gas would have a net effect of approx 41 pounds at the tailwheel. I looked and couldn't find the station for the ground contact point for the forward swept gear, but it is I'm guessing say 14 inches behind the firewall. If someone has that handy we can calc it pretty accurately. Anyways, what's in the plane when you weigh it makes a significant difference.

Flynengr

weght! wait! weight!

Agreed... sorta, kinda

22" is the number you're looking for. Which shrinks that 41#s up by about 30%... Pull out the back seat, hang the battery on the firewall along with a heavier motor mount, and I think you'll find that my reported t/w vs empty gross weights are gonna be pretty close... unless... the rest of the plane is a porker...

'55, a poll wouldn't cost you any time, and might be useful. Kevin recently weighed his, although like mine, it wasn't a feather weight, it was a good close example to compare to (fwd gear and long wings). Glidergeek was doing a Pponk recently and in corresponding with him I seem to recall his plane being very close in weight to mine (on scales), even with the fwd gear...

The tail weight seems excessive to me, because based on the little I have read about the airplane I *think* it should be nose heavy. Consequently I *think* slowed up like a 180 can be slowed, empty and light that airplane should be landing with nose up trim, or the trim wheel cranked pretty far back. But, I don't think that is the whole deal, because as we all know, you can get a 180 tail to weigh 500#s and it will still fly reasonably well.

I believe it is a new motor mount, so the thrustline *should* be good, and since the problem existed at least to some degree, before the engine swap, I don't *think* the motor mount is the culprit.

The reskinned tail cone is highly suspect, but without measuring who knows?

If it has been in a groundloop involving firewall replacement, it would not be far fetched to have that installed poorly, again leading to a bad AOI (thrust line). But I don't *think* it could be so screwed up it would go un noticed. Also I *might* know of several 180's that have longer bottom motor mount lugs to alleviate some of the motor sag we see and get a little better AOI, it works, but not to the extent we are talking about here.

I don't like 'stop to stop' assumptions much unless they're measured and prove accurate. It doesn't take much error to screw things up. I once had the stick aileron stops on my cub work there way loose. They angle down, and begin to diminish the stick travel. You always feel like your going stop to stop, but pretty soon you find out your roll has been chopped in half

I don't put much faith in performance tests with a very light wing loading and high power, so don't let the empty performance fool you. How many times have you flown an ag plane empty that flew just fine, only to load it up and find out it was a pig compared to one right next door that flew just the same empty?

Here's a thought... Have you looked in the motor mount channel / lugs at the firewall (inside)? Is it just me or does anyone else recall something about an A/D on the 175's that involved those cracking out and letting the engine essentially sag fwd and down, and in a couple instances completely off the airframe I don't know how their firewall attach compares to ours, but it is worthy of inspection... DId you guys use the rubber or aluminum bushings? Although again if it was that far out I would think someone looking for a problem would have found it by now. Spinner rubbing on the lower cowl?


Good luck!

First, I know nothing about Cessna horizontal stab design or attachment. But, a while back I was talking to a mechanic who said he had worked on a plane (I don't recall the type) and found the horizontal stab was installed upside down. They were flipped over and put on the opposite side of the tail. The mechanic said the difference in appearance was very subtle so easily missed. it had been flying like that for quite a while. Sounded screwed up to me and I don't know if that's even possible on a 180/185. I took a quick look at a 185 tail and couldn't see an obvious difference between the camber on the upper and lower surface, nor could I see how it was attached at the root. Maybe the sides are interchangeable and the airfoil is symmetrical. Maybe not.

It sounds like you've considered everything else, maybe consider the bizarre. Good luck.

Rob I checked those channels your talking about. I helped on the firewall forward. Theyre in good shape.
Another piece if the puzzle after talking to the rigging fellow. He was curious if the fat part of the excentric was towards the cabin. Apparently those need to be between 12 & 6 o'clock facing the cabin. Right side is close to 6 leaning to the outside a little (least lift). Pilot side is about 3-4oclock pointing out. How much significance?...idk yet. The sad part is the more I dig and look the more things I see that I know we're known but not recording or told. Major expensive sickening lesson. So sad when you think your dealing with someone honest and this happens. I have found several discrepancies that I'm am fairly certain the a&p owner knew of or did. Like logging removed controls stripped, painted and balanced. Plane was painted all together. Not stripped. Paint stacked on paint. Those kind of things let you know the kind of person your dealing with. Who knows what all will be uncovered. I continue to thank everybody for the ideas and help. I check or have checked every suggestion that comes in even if I don't remember to adress it specifically.