Cleaning up

[flyguy]

Anyone here done a airframe "cleanup" and made a careful check of any improvements in performance? I'm thinking simple changes such as going back to smaller stock tires and adding strut end covers. Maybe wheel pants at some point if they make a significant difference.

Any solid information appreciated.

DC

[Hank Jarrett]

Re: Cleaning up

As far as I can find the NASA stall study is the only real data and they were only looking at improved stall performance and the plane had mods that made it questionable as to representing a stock plane.

I have all the drawings and information to put a data probe on the wing strut and gather REAL data from a stone stock plane and then measure the impact of changes, but it was something Chuck and I were going to do when he moved here to the residential airpark we were going to build. The land for the airpark keeps falling through so we never did it. Someday I HOPE!!!! I really want to do this on our planes and get REAL NUMBERS for best range, lowest sink and the impact of different clean up mods.

From the THEORY we used while I was at NASA the biggest problems with our planes might surprise you. The tail wires have as much drag as a rear strut alone! The gap between the stabs and fuselage is another bad area, the tail wheel and springs are a real anchor but the second worst on the whole plane is the gear to fuselage and strut attach. Even tiny gaps and bumps close to the fuselage to strut/gear intersection have a huge impact, as do air leaks around the windows and doors.

All of these pale compared to the cooling drag. The estimates are that up to 50% of the total drag comes from engine cooling! The cooling outlet is NOT optimized. Leaking baffles are TERRIBLE and the inlet design is not sized right for drag! There are many areas that could be cleaned up easily (and some not so easy) but the real problem is how do you figure out which changes are the best bang for the buck. For that we need a baseline which is what I wanted to do.

So many projects and so little life span to do them all!

Hank

[flyguy]

Re: Cleaning up

I have see the video on testing the tail wire vs a streamlined strut. Really hard to adsorb that one as true.

Anyway I'm not going any distance with the 12D anymore so I'm considering some little projects to play engineer/test pilot with as I have always enjoyed that kind of activity in the past.

I can see doing something with the trailing edge of the landing gear arms for example. A German authored old book, that we had in the library were I worked, spoke of trailing edge importance. Wish I could remember the name of the book---sure would like to have a copy.

[N95334]

Re: Cleaning up

I was wondering if I could put SS streamline tail wires on my Taylorcraft BC-12-D ?
I added some simple cuffs to the forward struts at the wing junction. Could not tell and difference.
What about adding cuffs to the struts at the fuselage?

[Ragwing nut]

Re: Cleaning up

wheel pants and strut cuffs don't really make much difference. Your better off making sure the airplane is rigged properly and I usually run slightly less incidence in the wings. You legally can't run streamline tailwires and you probably don't want to pay for them either.

[Hank Jarrett]

Re: Cleaning up

I have see the video on testing the tail wire vs a streamlined strut. Really hard to adsorb that one as true.

Anyway I'm not going any distance with the 12D anymore so I'm considering some little projects to play engineer/test pilot with as I have always enjoyed that kind of activity in the past.

I can see doing something with the trailing edge of the landing gear arms for example. A German authored old book, that we had in the library were I worked, spoke of trailing edge importance. Wish I could remember the name of the book---sure would like to have a copy.

Any chance you are talking about "Theory of Wing Sections" by Ira H. Abbott and A. E. von Doenhoff? Great reference that every Aero Engineer I know has a copy of. Still widly available and one of the more affordable reference books. https://www.ebay.com/itm/Theory-of-W...YAAOSwY~1aENpw

Hank

[LostnSpace]

Re: Cleaning up

I picked up an X-Cub from CubCrafters and while they were talking about it, a guy there said they picked up near 15 MPH when they got rid of the cub type gear legs and went with the spring steel design, now the FX3 is out and they wanted better performance than the CarbonCub without going for more HP, they changed the design of the prop and went with fuel injection and probably more stuff and got 22 percent more acceleration than the CarbonCub, very neat stuff, like the sign in the speed shop many years ago stated "Speed costs money, how fast do you want to go", gary

[Hank Jarrett]

Re: Cleaning up

The most expensive way to go faster is HP. The cheapest is lowering weight and drag. Most practical (on planes as aerodynamically dirty as ours) is drag reduction. The lowest cost MPH you can gain is probably plugging up leaks (makes the cockpit quieter and the passenger comfort better too).

Trammel your plane and make sure it is STRAIGHT! Crooked planes will have much higher drag. If you have tabs on surfaces and they are bent, you are probably out of rig. I trammeled mine really carefully because I am anal. I also forgot to put the rudder tab back on and didn't notice for several years. She didn't need ANY yaw trim! Once I rigged the ailerons right she also will fly wings level without any trim. If you see a Taylorcraft with sheet metal tabs on the control surfaces that are bent, so is the plane.

Other easy fixes are shape of the tail wires (but that comes with some stiff problems with certification). Streamlined wires have unknown vibration qualities and the FAA HATES the word "unknown". Streamlined wires are expensive but NOTHING like the vibration testing the FAA would require!

Cleaning up the strut to fuselage and strut to wing areas is also pretty easy (and you don't need paperwork, it was there on most planes from the factory and people threw them away).

DO NOT try to seal up the control gaps!!! That WILL reduce drag but will also require a full test series to prove you didn't screw up the controlability. Cheap to do, expensive to prove it is safe. Down right dangerous to do to the ailerons. Air is SUPPOSED to go through the aileron gap!!!!!

Cooling drag is VERY effective, but hard to figure out how to do it well. Clean up the airflow through the cowl as much as you can. You will go faster and your engine will run cooler.

Now for the bad news. If you do EVERYTHING you can, you probably won't be able to quantify how much faster you go. Taylor actually did a pretty good job, especially with what he had to work with.

You can also put a steeper pitch prop on. Works great to go faster but is a direct trade of climb for speed. Got a 5,000' runway? Use a course pitch prop (the steepest you can legally use) and you will go faster. Want to enjoy flying, use a reasonable one and climb better. I am actually not in a big hurry. If I was I would buy a ticket on Delta. I DO like to see how fast I can go on the lowest power setting. It is fun to try to be as efficient as you can be.

One FREE speed trick is to go to a glider club and learn to fly the weather. I REALLY enjoyed flying to Kitty Hawk one time with a full size pilot with me on 65 HP and walk away from a Cessna 150 with one aboard. We cruised well ahead of him and he would dive to catch up. Then he would try to climb up to us and would fall behind. He did it several times and never could catch us. I had to prove I only had 65 HP against his 0-200. What he DIDN'T see was I was flying under a Cloud Street in a powerful lift area, He was in the down draft part of the rotor the whole way. He was basically having to CLIMB the whole trip while I was in a constant dive. Know your local weather! Sometimes you can move to the side a quarter mile and fly much more efficiently.

Hank

[likeTs2]

Re: Cleaning up

Forrest responded to a thread on this site regarding wheel pants and their effect on speed. He said that with wheel, strut and gear fairings a 65 should be able to get 100 mph.

AMEN to the glider flying. I started working on a glider rating a couple of years ago after I decided to get back into aviation. I believe it has made me a much better pilot than if I had just started flying power again.

[Robert Lees]

Re: Cleaning up

I get 100mph on 65hp without wheel pants, and they're a pain in the backside when you need to pump the tyres up or fill the wing tanks.

Plus they just look wrong...it's not a Pitts Special after all.

[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

[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

[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

[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

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.