110 MPH Taylorcraft !?!?

[jCandlish]

Re: 110 MPH Taylorcraft !?!?

Apologies to the millions of downtrodden T-craft owners who have had to hear this same lengthy ranting from me already...

Still flying flippers? Is your trim system at all effective?

I've been thinking about the possibility of putting a bellcrank on the inner hingepin that would transfer the torque moment from the flipper-rod to a servo tab on the elevator,

That would be way easier than retro-fitting the b12 trim.

Cheers
jCandlish
.

[flyguy]

Re: 110 MPH Taylorcraft !?!?

Kevin, I think you may have answered one of my questions. I have been curious as to what a 74 inch (46-45 or so) would do on an -85, not for floatplanes, but for cruise on normal gear. That figures out to about 2-1/2 square ft of additional thrust area, and it is all out at the tip where it does the most good. That is a BIG additional chunk of air.

Do you know, or does anyone know why the 72 inch limitation on the -85 BC12D? I thought it might have to do with supersonic tip speed, but it doesn't even come close, if my calculations are correct.
What is that all about, if the longer prop works better?

I have heard 1. Long (74) props will not turn up on an 85. To which I said, "Well flatten the pitch," and someone said, "It will not cruise good if you do that." Makes some sense, but apparently neither is true----??
What is the haps on the 72 bit?
Darryl

[crispy critter]

Re: 110 MPH Taylorcraft !?!?

Kevin, I think you may have answered one of my questions. I have been curious as to what a 74 inch (46-45 or so) would do on an -85, not for floatplanes, but for cruise on normal gear. That figures out to about 2-1/2 square ft of additional thrust area, and it is all out at the tip where it does the most good. That is a BIG additional chunk of air.

Do you know, or does anyone know why the 72 inch limitation on the -85 BC12D? I thought it might have to do with supersonic tip speed, but it doesn't even come close, if my calculations are correct.
What is that all about, if the longer prop works better?

I have heard 1. Long (74) props will not turn up on an 85. To which I said, "Well flatten the pitch," and someone said, "It will not cruise good if you do that." Makes some sense, but apparently neither is true----??
What is the haps on the 72 bit?
Darryl

The longer props will not turn up on the 85 unless it is a really strong 85. I have found that a 72/46 or 72/48 makes for a good cruise prop on a C85-8 and a little less pitch on the -12.

[crispy critter]

Re: 110 MPH Taylorcraft !?!?

How much wash and aileron droop do you suggest?

When we assembled the ribs on the new spars we lowered the ribs on the front spar about 1/8 of an inch leaving about 1/8 of an inch clearence between the rib and top of the spar. Then we basically rigged both wings flat and added just a tick of washout at the tip(very little). The ailerons were a very tight fit all the way around with very little clearence after all the fabric was on and we rigged them so that in level flight they were perfectly flush with the wing(about 1/8" droop with 20lbs of cable tension). Hope this helps.

[VictorBravo]

Re: 110 MPH Taylorcraft !?!?

Still flying flippers? Is your trim system at all effective?
.

Well, as they say in the music business... my flippers are bigger than your flippers

I repaired my damaged flippers so well and so neatly, that they may be a wee bit larger. My craftsmanship with them was sadly slightly sub-par, so I had to add a few layers of filler, which accidentally resulted in a better airfoil shape than they were in 1940.

With these larger flippers, I have enough trim force to hold the nose level at speeds up to and exceeding 110 mph IAS. They allow me to trim it down to about 65 MPH on the slow end, which is better than before.

If I ever were in a position to repair pre-war trim flippers again, my workmanship would probably be so sub-par as to require several more layers of filler on the bottom, resulting in an inverted Clark Y airfoil which would likely be able to slow the minimum trim speed even further.

If you search the Forum for some of the previous posts on the subject of pre-war trim flippers, you may even see some sketches and p[hotos.

[Guest]

Re: 110 MPH Taylorcraft !?!?

I recall looking up those flippers 40 years ago (when I had a BL-65 that had one) I they called them "flettners".

Anyone else ever here them called that?

Flettner was a famous aviation engineer.

I did find this;

http://history.nasa.gov/monograph12/ch6.htm

http://en.wikipedia.org/wiki/Servo_tabs

Dave

[VictorBravo]

Re: 110 MPH Taylorcraft !?!?

Anyone else ever here them called that?

Flettner was a famous aviation engineer.

I never heard Taylorcraft trim tabs called Flettners, but I also remember hearing of Flettner as a famous engineer. I remember his name associated with ailerons and trim tabs of one sort or another.

The trim tabs on pre-war T-crafts were marginal with 40 HP and 65 HP... but then they became somewhat less than useful with the enclosed cowl upgrade. MY guess is that the faster speeds available with the closed cowl (less drag) put the airplane beyond the capabilities of the trim tab. T-craft soon went to the "normal" elevator trim tab and simply forgot about how to deal with 100 mph speeds on the old external tab.

Larger trim tabs are far more effective. My airplane will slow down to 65 MPH power off trim speed on the larger tabs, and will hold speeds of 120 MPH power on at the high end. At least one other local pre-war airplane at my airport has modified tabs (riveted extension), and I suspect many many others have some kind of improvement made.

Anyone wishing to do such an improvement should be careful not to create a situation where the aerodynamic forces are unbalanced compared to the pivot position. If you add any area in front of the pivot, make sure you are adding a little more than the same area behind the pivot. A friction washer (leather, sanded phenolic, etc) at the forward control arm (pilot lever) will greatly help against slipping. This is an instance where smooth easy operation is bad, and friction is good.

[flyguy]

Re: 110 MPH Taylorcraft !?!?

This is a non-technical thought from personal experience only. The first Taylorcraft I owned had a "home-made" wood trim tab on the elevator. (what did I know about light aircraft then) The first time I flew in formation with a friend his comment was, "You had best get back on the ground as soon as possible, your tail assembly is fluttering."
I am speaking generally, but you may wish to avoid adding MASS to the trailing edge of (any?) trim tab.
My lay understanding (well, maybe a little better than that) is that you want to keep the area to mass ratio high, ie mass lower, area larger, downwind of the pivot point. Best check it out really well before modifying trim tabs.
Darryl

[VictorBravo]

Re: 110 MPH Taylorcraft !?!?

you may wish to avoid adding MASS to the trailing edge of (any?) trim tab.

He's 100% right, and I forgot to mention it. In addition to making sure the trim tabs have a little more area behind the pivot, you should also make sure it is nose-heavy around the pivot too. Sorry for the forgetfulness and thanks to DC for pointing it out.

The external trim tabs have the advantage of giving you an extra emergency control to use if you lose a main elevator cable.

Pop Quiz: Any of you post-war T-craft owners ever thought about how you would get control of your airplane back if you lost the elevator and the post-war elevator trim?? Any of you thought about how you would get it back if you lost the entire A-arm (or H-arm) main control column??

[astjp2]

Re: 110 MPH Taylorcraft !?!?

He's 100% right, and I forgot to mention it. In addition to making sure the trim tabs have a little more area behind the pivot, you should also make sure it is nose-heavy around the pivot too. Sorry for the forgetfulness and thanks to DC for pointing it out.

The external trim tabs have the advantage of giving you an extra emergency control to use if you lose a main elevator cable.

Pop Quiz: Any of you post-war T-craft owners ever thought about how you would get control of your airplane back if you lost the elevator and the post-war elevator trim?? Any of you thought about how you would get it back if you lost the entire A-arm (or H-arm) main control column??

Parachute!

[Ragwing nut]

Re: 110 MPH Taylorcraft !?!?

110 mph is a realistic number with 85hp or 100hp. I have had multiple 75hp conversions cruise around 105 with a metal prop.

74-43 prop is too flat for an O-200 if you want speed out of it. I never liked the 43 pitch on my DeLuxe, it would not keep the tail up. 45 pitch should be perfect on an O-200. I ran a 71-48 metal on our 85 hp L-2M with good results. I have also built quite a few 74-44 wood props for 85's with good numbers as well.

[astjp2]

Re: 110 MPH Taylorcraft !?!?

110 mph is a realistic number with 85hp or 100hp. I have had multiple 75hp conversions cruise around 105 with a metal prop.

74-43 prop is too flat for an O-200 if you want speed out of it. I never liked the 43 pitch on my DeLuxe, it would not keep the tail up. 45 pitch should be perfect on an O-200. I ran a 71-48 metal on our 85 hp L-2M with good results. I have also built quite a few 74-44 wood props for 85's with good numbers as well.

Well I had a 74-46 and could only get 2550 rpms redline, and 99 kts and I had it repitched to 43 and got 2700 and 106 kias/gs (not mph) with the same prop. I climb at 1500 fpm from sea level to 6000, I would rather have the long prop, Borer does it and does it well with the long props. Tim

[VictorBravo]

Re: 110 MPH Taylorcraft !?!?

Parachute!

In the early days of radio controlled model airplanes, it was found that using the rudder only, you could not only climb and dive and turn, but you could actually complete most of the basic aerobatic maneuvers, stalls, rolls, loops, etc. In fact, aerobatic competitions were held for models with nothing other than a moveable rudder.

This OF COURSE required the model airplane to be set up to do that.

But, if you have a conventional configuration airplane that is flying more or less in stable level flight, by using and modulating the inherent yaw-roll coupling against the pitch stability of the airplane, you can keep it right side up, change direction, counteract stalls, etc. enough to crash land it someplace with the wheels on the bottom.

Now if you have the luxury of a working throttle, this gets quite a bit easier, and you could even have a good chance of not seriously damaging the airplane.

Like I've always said, model airplanes saved the world

[T.Taylor]

Re: 110 MPH Taylorcraft !?!?

He's 100% right, and I forgot to mention it. In addition to making sure the trim tabs have a little more area behind the pivot, you should also make sure it is nose-heavy around the pivot too. Sorry for the forgetfulness and thanks to DC for pointing it out.

The external trim tabs have the advantage of giving you an extra emergency control to use if you lose a main elevator cable.

Pop Quiz: Any of you post-war T-craft owners ever thought about how you would get control of your airplane back if you lost the elevator and the post-war elevator trim?? Any of you thought about how you would get it back if you lost the entire A-arm (or H-arm) main control column??

How about a right proper inspection before flying ?

[crispy critter]

Re: 110 MPH Taylorcraft !?!?

He's 100% right, and I forgot to mention it. In addition to making sure the trim tabs have a little more area behind the pivot, you should also make sure it is nose-heavy around the pivot too. Sorry for the forgetfulness and thanks to DC for pointing it out.

The external trim tabs have the advantage of giving you an extra emergency control to use if you lose a main elevator cable.

Pop Quiz: Any of you post-war T-craft owners ever thought about how you would get control of your airplane back if you lost the elevator and the post-war elevator trim?? Any of you thought about how you would get it back if you lost the entire A-arm (or H-arm) main control column??

I lost up elevator once in my dad's 1948 Cessna 170(cable broke at the control horn in the fuslage).I was still a student pilot and I was practicing t/o's & lnds. It wasn't as bad as I expected. I simply trimmed full up elevator and done a gentle wheel landing. I taxied up the way,jumped out and dad complimented me on a beautiful wheel landing then busted my chops because I taxied all the way in without holding full up elevator......he was not so PO'ed after I told him why,in fact he was very impressed.