Pre-war Trim Tab Upgrade Report

[Dano"T"]

Re: Pre-war Trim Tab Upgrade Report

We approach at 50 when operating off Field or tight strips for short landings.
60 is perfect at an airport...it gives a nice soft flare and 3 point landing. I don't typically trim for an approach at 50...I just trim it to where it feels good and then hold a little back pressure to slow to my desired speed on final. Typically these approaches are tight patterns and quite short final and usually involve a side slip. I make sure I'm at no less than 55 in a slip though and I slow it back down when I roll out of the slip with a little back pressure. When I fly into an actual airport I fly a normal pattern and approach at 60 and I trim it in for that speed. I was taught that not only is your stall speed slightly higher while slipping, but your a/s indicator can give erroneous readings because of the unusual attitude and airflow across the pitot.

[VictorBravo]

Re: Pre-war Trim Tab Upgrade Report

We approach at 50 when operating off Field or tight strips for short landings.
60 is perfect at an airport...it gives a nice soft flare and 3 point landing. I don't typically trim for an approach at 50...

I can hear my old crusty instructor now, shouting across the Cessna 150's cabin... "EVERY landing is a short field landing!... EVERY runway is only twice as long as the length of the painted numbers!!"

Actually that's not true at all, my instructors were mostly kids building time toward an airline job, but in my mind I SHOULD have had a tough old instructor like that

Glad to say that I still try to hit the numbers on every landing, and hit them about than half the time.

Dano I appreciate the clarification, but if you're bombing down final 20 mph over stall speed, where do you scrub off all that extra energy? It would appear that you'd have to "aim" for a point 2 or 300 feet before the numbers, and float that 20 mph off to land at 40.

The times I have tried to come down short final at 50, the airspeed is not very stable and the airplane can easily gain or lose several miles an hour in normal, small gusts. In other words, airspeed control at 50 is a little more difficult to maintain when you're holding back-pressure on the yoke.

It also may just be plain old incompetence on my part, there is a bit more rust on my flying skils than I care to admit these days. I gotta go back out to the dry lake and set up some cones or something.

[Dano"T"]

Re: Pre-war Trim Tab Upgrade Report

Bill,

You're right...it's a good idea to keep up those skills up so if at some point you have to land short...you'll be relatively comfortable doing so. I guess I'm guilty of getting lazy when there is 5000' of ribbon in front of me. 90% of my landings are either on a lake or my 1000' farm strip. My hangar is at a little strip that I bulldozed and it is short and not necessarily as smooth as it could be. I have woods on one end and small power lines at the other. My dad landed there other day and he didn't settle down until about halfway down the strip or better...I said "have some trouble getting her to quit flying dad?" He says " I was just trying to decide if I should go under or over the wires on the go around when she finally settled in". We laughed....he wiped his brow and He said he came in a little fast and sped up a little more in a side slip.

[TimHicks]

Re: Pre-war Trim Tab Upgrade Report

VB,
Very cool experiment. Thanks for letting us follow along. I know you're not planning further iterations until you get more pressing tasks done, but just for discussion while this thread is alive I thought of a couple of things:

You mentioned possibly trying negative camber surfaces in the future. Might a quick-and-dirty way to achieve this be to put the current left tab on the right and the right tab on the left?

Or, since you have more nose-down authority than nose-up authority, what about adding a fixed tab to the elevator to offset your range towards nose-up. Of course doing this may add enough trim drag to take away your hard-won cruise speed gains.

[taylorcraftbc65]

Re: Pre-war Trim Tab Upgrade Report

Bill,
The "flappers" that I have on my BC65 stay put at pattern speeds after I followed the advice that I recieved on this site right after I bought the plane and tightened the through bolt on the lever bracket under the seat, along with oiling the leather washers on either side of the lever. It runs out of authority at about 97 IAS, and flat out at 105 I'm shoving forward on the yoke and even then, the bird is climbing. Talk about an efficient wing.
It's OK though, I like cruising around at 95 IAS, and the trim still works at that speed.
Having a set of "wings" back there that developed downforce without having to be deflected to near maximum at 95 would sure be easier on the engine and fuel burn though. Brie

[VictorBravo]

Re: Pre-war Trim Tab Upgrade Report

Tim, you're right on the money about inverting (swapping) the trim tabs. I was thinking about that as I was writing that post. If the holes line up I'll do it in a heartbeat. these trim tabs are now firmly in the "multi-patch interim version" arena, and there would definitely be a pretty set built for the long run. If I had to give up the 1 or 2 mph cruise speed to get the ability to trim it for 50 on final, I'd do it gladly.

Brie, you must have gotten the deee - luxe version, because there ain't any leather washers on my trim tab lever bolt. There was only a bolt and a wing nut, and there was no wire or loctite or Cotter pin to hold it. I turned the wing nut another quarter tuen tighter and safety-wired it, and now it has plenty of friction.

For what it's worth, you might think about making a slightly larger set of tabs (but still the stock shape and construction). You can get probably 80% of the benefits I got, with 20% of the effort. They go on and off with three screws in 15 minutes, so if anyone looks at you the wrong way you can just go back to stock. Just make them so that there is another 25% more total area, and leave the pivot point at 25% of the new chord line for safety. Make the curve around the leading edge to the tip so the tab does not interfere with the lower stabilizer lift wire. For best performance, do NOT taper or curve the tip at the trailing edge of the tab. The trailing edge of the tab should go straight all the way to the very tip, with a 90 degree angle straight forward at the tip for a few inches, then the rounded radius toward the leading edge. Make the leading edge "fold" radius as large as possible, which in this case should be 3/8". If you want, I'll send you a sketch of what I suggest, but you will need to get a wink and a nod from your IA to "repair" your broken trim tabs in this way.

[taylorcraftbc65]

Re: Pre-war Trim Tab Upgrade Report

Bill,
Thanks for the clarification, yes I would like the drawings. I think my plane might have been a Delux model because it has both doors, and the right wing tank as well as the cowl tank. Brie

[VictorBravo]

Re: Pre-war Trim Tab Upgrade Report

Bill,
Thanks for the clarification, yes I would like the drawings. I think my plane might have been a Delux model because it has both doors, and the right wing tank as well as the cowl tank. Brie

Nahh, I was referring to the deluxe leather washers Just being a smart ass. If I'm not mistaken, the pre-war deluxes had a rear fuselage tank under the baggage sling, not a wing tank. I actually had one of those once, with a hand operated pump to transfer the fuel back into the nose tank. Kinda cool, but not as idiot proof as gravity.

I'll try to make up some sketches with a pen and paper, scan them into the PC, then trnsfer them to the Mac, then post them. Ain't technology grand?

[taylorcraftbc65]

Re: Pre-war Trim Tab Upgrade Report

Bill,
Thanks, I would really appreciate the drawings. Hey Forrest, is that true about the under sling tank? are they still available? If not, how about the drawings?? Brie