Cleaning up

[PA1195]

Re: Cleaning up

One mechanic was good and knew streamlined wires. He believed that where they crossed required some sort of connection better than the usual wraps of electrical tape and away you go kid. He made something out of wood or rubber (?) that separated the wires yet held them from banging together. Over the years in that plane some wires had to be replaced due to metal to metal contact from vibration.

The 336/337 sound is different. Never flew or rode in one but the props must have disturbed the one behind I guess. My first flight instructor flew them and an L-19 over SE Asia as spotter 50 years ago. I think that was his story while sitting a C-150 with me.

Gary

[LostnSpace]

Re: Cleaning up

Years ago on a C-185 with EDO 3430 floats I had periodic issues with streamlined cross wires that were part of the EDO installation rigging. Different scenario than a tail wire setup of course. Unless they were oriented just right and tensioned properly they'd vibrate and hum at certain power settings and airspeeds (the frequency deal Hank notes?).

Mechanics would set the wire tension per their personal specs on yearly installation and use an adjustable wrench against the streamlined flat to turn the wires to tighten. Sometimes they'd end up facing the wind differently at one end of a wire than the other. I never had one break but often wondered if and when. There's four per crossed per float installation so maybe if one did break the rest would still hold the assembly together. Getting the wire's streamline oriented in the right direction with the airflow under the plane's belly and correct tension was important.

Gary

I used to fly Stearmans for ag work in So. Cal. and when a wing panel would get replaced, I was often picked to do the check flight, several times one of the wires were off alignment and it would sound like a Cessna 336/337 SkyMaster was real close to me, gary

[Ragwing nut]

Re: Cleaning up

besides rigging, cooling drag is the only other biggest increase you may see. Anything else I think is negligible short of clipping wings. Taking a lot of the wash out of the wings will make a huge difference, but is gnarly on stall if it snaps.

[PA1195]

Re: Cleaning up

Years ago on a C-185 with EDO 3430 floats I had periodic issues with streamlined cross wires that were part of the EDO installation rigging. Different scenario than a tail wire setup of course. Unless they were oriented just right and tensioned properly they'd vibrate and hum at certain power settings and airspeeds (the frequency deal Hank notes?).

Mechanics would set the wire tension per their personal specs on yearly installation and use an adjustable wrench against the streamlined flat to turn the wires to tighten. Sometimes they'd end up facing the wind differently at one end of a wire than the other. I never had one break but often wondered if and when. There's four per crossed per float installation so maybe if one did break the rest would still hold the assembly together. Getting the wire's streamline oriented in the right direction with the airflow under the plane's belly and correct tension was important.

Gary

[Hank Jarrett]

Re: Cleaning up

The thing about reducing drag is it is NOT cumulative. If you put ten mods on that are proven to reduce drag for a one knot speed increase INDIVIDUALLY, you will NOT get ten more knots! Kind of like those mileage increase changes you used to see for cars that "guaranteed" a 10% mileage increase. If you put 10 of them on your mileage doesn't go to infinity.

That said I am really looking forward to the 45 being done so I can play with drag reduction with instrumentation to see where real improvements can be made. I think streamlined wires on the tail wouldn't be cost effective, but want to see what a streamline plastic fairing over the wires would do. I DO NOT suggest anyone try this until they have an instrumented plane! One side effect of turning round wires into streamlined is they will vibrate at some frequency. You DO NOT want that wire vibrating fast enough to fatigue the threaded area and breaking! You might hear or feel it, but you might not. If I did it I would have a sensor on it and do a full spectrum test to prove it WILL NOT vibrate and I suspect the FAA would require it if I wanted to go past an experiment (with a temp change to the registration to do it!) and get an STC.

Drag reduction is a great idea, but needs to be done CAREFULLY if you start changing things that could kill you if they fail.

Hank

[Robert Lees]

Re: Cleaning up

... Is it legal to change the tail wires with streamline ones?

It is if you have an STC to that effect. I don't believe one exists.

The difference in drag is minimal, so much so that if you were in so much of a hurry to warrant the expense of changing them, buy a Cirrus or an airline ticket
Rob

[N95334]

Re: Cleaning up

As Hank pointed out the tail wires have just as much drag and the rear lift strut. I asked this before. Is it legal to change the tail wires with streamline ones?

[PA1195]

Re: Cleaning up

I was told that by Old Timer pilots. Might be true especially after it's done with lots of hard work. But except for the leading edges of the various airframe components and propeller, dirt, debris and water from rain in flight tend to collect and flow slowly back along the airstream-surface boundary layer interface.

Perhaps just a good de-lousing and wash would achieve the same result? At 100 mph how much is to be gained? Maybe with fast planes that's important.

Gary

[N95334]

Re: Cleaning up

Just wondering if you wax your entire aeroplane what would that due to cruise speed. My guess not much and waxing the entire aeroplane is a very long tiring job.

[Ragwing nut]

Re: Cleaning up

I used to run a 72-46 prop on my 85, and would get 115 all day long with 2 in and full tanks. One thing about a Tcraft is that if you put more power on, it goes faster as well as climbs better.... unlike a J3 that just jumps off the ground a little quicker and uses more fuel.
The one thing I'd love to do to a Tcraft is to put a moveable stabilizer like a Cub has. I think that'd really show some speed and handling improvements!
John

I ran a 71-48 and would get similar numbers. And I have considered the same thing on using a piper jack screw. My clipwing just might end up with it.

[flyguy]

Re: Cleaning up

Tim, my first BC12, that I later referred to as the "deathtrap" one, didn't have wing root fairings when I bought it. It caused noticeable shaking/vibration of the rear of the aircraft. It was at its worst during the flare. Don't remember if I figured it out before I ordered fairings and installed them or realized the problem went away with the fairings installed. My conclusion was that the open wing roots were causing turbulent air flow over the tail assembly.
DC

Pre or post war? the angle of incidence is different...maybe that is what could cause a difference in flight characteristics.

[astjp2]

Re: Cleaning up

I have streamlined farings on my gear, no wing root fairings and can fly 106 Knots at 2500' msl at 2600 rpm with my old prop. Having covered gear was more beneficial than the wing root fairings. I do plan on putting good strut fairings, wing root fairings and cleaning up the gaps at the horizontal to fuselage intersections. Tim

[flyguy]

Re: Cleaning up

Hank, that book was one probably written after WWII by a German engineer who worked on aircraft before and during the war. I remember it having a part about the effect of dirt and mud on BF-109 (right designation?) wings.
Some very interesting info on using small thin airfoils to correct turbulence behind poorly streamlined shapes.
I might look around some, you never know.
DC

[PA1195]

Re: Cleaning up

Clean versus big tires, open gear legs, skis, and floats. I don't know clean in a Taylorcraft. Mid to upper 90's GPS with a 74-40 in front of a C-85 Stroker @2300-2350 burning 5-6/hr. They must be fun light and clean but up here the idea is go off airport with every flight so all the gear changes. My first T had a Beech-Roby prop and C-85. I never flew it but the owner said it helped. Maybe one of those new Sensenich adjustables (http://www.sensenich.com/products/item/138) would be good?

Gary

[N96337]

Re: Cleaning up

I used to run a 72-46 prop on my 85, and would get 115 all day long with 2 in and full tanks. One thing about a Tcraft is that if you put more power on, it goes faster as well as climbs better.... unlike a J3 that just jumps off the ground a little quicker and uses more fuel.
The one thing I'd love to do to a Tcraft is to put a moveable stabilizer like a Cub has. I think that'd really show some speed and handling improvements!
John