Cleaning up the drag??

[Robert Bradbury]

Hi all

I'm trying to clean up the drag on my float plane and am wondering what is
the list of concerns worst to best so that I clean up the worst areas first. I am cruising
at 75 whereas many on the list with floats cruise between 85-95 especially with the
C90 that I have. If I could get to 90mph I would be so much happier .

My list of areas, best guess, are as follows:

1) 36 feet of 5/16" flying wire on the floats has to be a whole lot of drag. I have access to streamlined flying wires that I'm sure if replaced would be a big help.

2) I don't have fairings over the 6 attachment areas, 4 on the floats and the two wing attachment points.

3) My doors don't fit snug and the sliding window on the left side is recessed such that there is a pocket created almost 1 inch deep at the aft part of this window. A flush window and tight sealing doors must be better. Oh and my doors are heavy, is there a lighter wooden alternative or otherwise just plain lighter door?

4) My wing root fairing were hand made for me and really do not fit great. You can easily see some waves on the long runs and the wing leading edge doesn't have a good tight fit.

5) The tail flying wires also being round could be changed out to streamlined
wires though 16 feet of 3/16" wire is not the end of the world.

6) Unique to my home built floats ( like aqua ) is a square spreader bar that I covered with an al. envelope. The envelope is now pushed back forming a not so streamlined shape. about 2 feet of the square spreader bar is exposed also contributing to the drag. I'm thinking about cutting the square off leaving a one foot stub at each point so that I can slip a streamlined spreader bar over as a permenant replacement . What would be ideal is a new float c/w fluted bottoms however this is not feasible at this time and too time consuming of a change.

Any thoughts , experiences would be appreciated .

Robert

[flyguy]

Re: Cleaning up the drag??

Robert,
Doesn't that 74x39 run out of stuff pretty quick at cruise?
Darryl

[Robert Bradbury]

Re: Cleaning up the drag??

Robert,
Doesn't that 74x39 run out of stuff pretty quick at cruise?
Darryl

Could be part of the equation but it still does not explain why similar aircraft
get better performance.

I think my floats are a key problem here too. I am thinking that the floats perform so poorly than I cannot get to the step and thus am compensating
by lowering the pitch. I have a friend with a Champ C90 and 1800 floats with
fluted bottoms. The floats are as light as 1400's so he is getting the best of both worlds. He's taken off at 1900lb, whereas I could not even attempt that.
He also cruises on this setup at 90 or so. Problem is these custom floats are
18,000US .....ouch!!

[flyguy]

Re: Cleaning up the drag??

I know zip from floatplanes, but I am curious, what is the break water airspeed for a Taylorcraft?
Darryl

[MNJoe]

Re: Cleaning up the drag??

Robert,

Have you weighed your floats? you said before that they are 1650 are they not EDO's Does the airplane get on step by it self or do you have to give it forward elevator? I have a set of 1420 Baumann's that I have not flown on yet but last summer I had 1320's and a small prop and it took 50 seconds with two people and 20 gallons of gas I probably did around 85-90 mph

Joe

[Robert Bradbury]

Re: Cleaning up the drag??

I know zip from floatplanes, but I am curious, what is the break water airspeed for a Taylorcraft?
Darryl

Once on the step( the first goal) I accelerate to about 40MPH and at that time I can pluck her out of the water. Mine will immediately accelerate to
50MPH out of the water and then I can establish a climb as necessary.

Robert

[Mark Julicher]

Re: Cleaning up the drag??

FWIW, a round object (i.e.wire) produces approximately the same amount of drag as a streamlined object of 10 times its diameter. You should see a speed increase if you swap out your brace wires, although that can be an expensive gain in speed given the price of streamline wire.

All the other spots you mentioned are causing some drag and each item you clean up will help a bit. I like cleaning up fairings and connecting points, although I will say I did not see any speed change when I put my strut cuffs on.

[flyguy]

Re: Cleaning up the drag??

Thanks Robert. T's sure are amazing planes. I've done soft-field T.O.'s but truthfully never checked the airspeed at ground break.
DC

[VictorBravo]

Re: Cleaning up the drag??

You should see a speed increase if you swap out your brace wires, although that can be an expensive gain in speed given the price of streamline wire.

Here's a way to do it on the cheap, as well as protecting your tail wires from water and impact damage. You would have to do it in clear plastic to allow visual inspection.

[Robert Bradbury]

Re: Cleaning up the drag??

Robert,

Have you weighed your floats? you said before that they are 1650 are they not EDO's Does the airplane get on step by it self or do you have to give it forward elevator? I have a set of 1420 Baumann's that I have not flown on yet but last summer I had 1320's and a small prop and it took 50 seconds with two people and 20 gallons of gas I probably did around 85-90 mph

Joe

Joe

do you still have the 1420 Bauman's and what about the 1320's ??

[Pearson]

Re: Cleaning up the drag??

Robert,

I agree with Mark about the round wires verses the streamlined stuff.

Have you checked your airspeed indicator? A GPS, or just flying alongside a buddy would tell you if you are really only doing 75.

I don't know anything about floatplane rigging. But in order to get a 15 mph speed increase you are going to have to do more than clean up the fairings and a side window. I would be looking at the big stuff like the float rigging, wing rigging, prop pitch, etc.

[Robert Bradbury]

Re: Cleaning up the drag??

Robert,

I agree with Mark about the round wires verses the streamlined stuff.

Have you checked your airspeed indicator? A GPS, or just flying alongside a buddy would tell you if you are really only doing 75.

I don't know anything about floatplane rigging. But in order to get a 15 mph speed increase you are going to have to do more than clean up the fairings and a side window. I would be looking at the big stuff like the float rigging, wing rigging, prop pitch, etc.

If I keep the plane and floats I will cut a foot off the back of the floats, install steamlined spreader bars ( rectangular at present with streamlined envelope that is not efficient) streamlined flying wires( or do as Mark suggests) and clean up all the other points of drag. Next is to REALLY check the washout on the wings
as I think even though I tested and rigged per the book I may have introduced some error in my interpretation of the instructions. Next will be
addition of 15 ponies by way of high compression cylinders and a twist of the
prop back to 74X72 or 73 .
If I sell the ship first I'll be into a 180HP Bushmaster on 2350 Wiplines before the spring .

[Pearson]

Re: Cleaning up the drag??

Robert

Adding horsepower is an expensive way to gain speed. Fifteen horsepower may get you a few mph, but even that isn't going to get you up to 90-95 mph. I think if I were you, I would be searching for someone that is very knowledegable in float rigging.