Aircraft Speed on floats

[Robert Bradbury]

I know I've been down this road before, but it bothers me that
some guys are getting 105 mph with a 100 hp on floats and I
with a 95 hp C90 can only get 75-80 at best . Could it be the
rigging, angle of the float deck ( I'm using 3.5 degrees of opening
relative to the aircraft centerline), drag of the rigging etc.??

On a scary note: I somehow got into a spin while practicing
stalls about a week ago. The aircraft did not want to come out
of the spin it seems until I applied power . I've practiced stalls
without issue many times before and I'm perplexed at why
this happened . Anyone with any comments or experience
doing spins on floats . I know they are illegal and have no desire to practice the same however, obviously they can happen and
one should know how to recover if the procedure is different
with float equiped aircraft .

[Jim Hartley]

good opporutunity to compare notes!

Hi Robert!

I have a BC-12D with a C-85 and a Sensenich 74ck-0-40. Pretty flat pitch from what I gather from discussions with others.

I think it is a good set up for getting off the water as quickly as possible with proper technique,however my cruise performance suffers.

I do not have a GPS but I have done time-speed -distance computations and I show about 80 mph +...close to what you show. The airspeed indicater shows 90 mph or better.

Hey Dick Smith!! Reply if you would. You have a prop similar to mine. Perhaps even finer or flatter pitch right? What are your ground speed numbers?

On the "scary note" Robert, I would like explore that a little more.
Would you describe how you entered the stall? Do you have a inclinometer or a slip or skid indicator. I did not until last year and although I concentrate on seat of the pants flying,nothing beats an instrument reference that shows me that I am succeeding in coordinated flight.

[matsuthunder200]

hi jim long time Robert , I also have bc12d with a c-90 cont with a 74-38 sens, prop at cruse i get 80 mph but the performance is at its best for getting on and of the water. I have a good gps and am always checking my groundspeed. When i first got my floats installed i had a 72- 48 mc. prop. i crused between 90 and 95 mph but it realy lacked the performance on and off the water . Personally i realy need the perf, and i find myself smiling just as much at 80...

[Dick Smith]

Float prop

Jim, with a 70.5 X 39 Sensenich, I'm at about 80 mph. Will do some more checking, using GPS, as soon a these winds lay down. Like you guys, getting off the water is the main concern. (C-85 with 1400 floats)
It's getting to be fall here for sure, after an unbelievably nice summer. Saw a big flock of geese yesterday and 8 trumpeter swans were feeding in front of the house yesterday. Plus a big cow moose with two calves waded in front of the plane. A friend gave me about 65 pounds of moosemeat...some of the good stuff off the hindquarters! We've got plenty of heat...and we'll soon be into ski conditions...life is just pretty good! Dick

Robert, I sent you a private email through this list.. Lance, here is a pix from over at "The Mudhole" on the Kustatan.

[matsuthunder200]

Nice pic. dick..Thats where we have our pick ups for our raft trips. We drift from sibs lake to the mud hole what a blast for silvers!!!

[Dick Smith]

First Taylorcraft flight

Lance, this is a pix of my 12 year old nephew, with a Kustatan silver. He had just had his first ride in a Taylorcraft on floats.The biggest fish he had ever caught was a 5 inch trout! This is what makes flying a lot of fun...look at that grin! Dick

[Grant S. Bailey]

Dick,

Do you have an electrical system in your T-craft? If so, what is the empty weight of your plane?

[matsuthunder200]

like the pic dick.. I need to figure out how to post a pic on this thing one of these days.. I should be in kenai in a few days haft to fly the t-craft back to wasilla. Its at the kenai float pond....

[Dick Smith]

weight/elect.?

Grant, I'm 890# on wheels and 1005# on floats. No electrical other than wiring for nav. and tail lights. With lexan skylight, lexan door cutouts, beefed-up gear, big baggage, straight axles, rear sidewindows, float fittings, individual seats, hyd. Cleveland toebrakes, antennas, etc., ...everything adds up. We operate near sea-level and in cooler wx than most folks, so these smaller engines (C-85) are putting out more power than some might get in other places. Wish I was lighter...but I like the utility provided by the layout. Dick

[Robert Bradbury]

So it appears I am in the range( 80 MPH ) that others are in tho
I hear from time to time of someone doing 100 MPH . I guess
these folks are using a coarse pitch and sacraficing their takeoff
performance.
My C90 has a Sen. 72 X 39 at present and I may even go to a
38 pitch which i am told is the ideal pitch for a C90 .
I don't mind the 80 MPH cruise, but not being able to take a
good load on those warmer days , or wondering if I'll be able to get out of those smaller ponds can be bothersome .
I'm considering a NSI Subaru engine as a replacement with variable pitch prop. The engine is 110 HP or 150 in the turbo version and the same weight as my C90 burning less fuel too .
Oh and B.T.W., my ship is 1040 empty on the 1650 floats and I
have all the gadgets like Dicks plus an electrical system and every
instrument one can think of. Yes.................................too much !

Jim Hartly,
thanks it is nice to be back. And about this spin. I was
doing normal power off stalls with the stick back picking up the wings with the rudder . I did intend to hold the stall for a bit instead of an immediate recovery. The left wing dropped first I
picked it up then boom, the left wing then snapped and we were looking at Terra Firma . I do have a bank/slip indicator but was not
looking at the same . Straight ahead stalls with a slight tailwind if
I recall .

[Steve Long]

slow on floats

Robert, Jim, Dick and group.

I fly an F-21 with an 0235 Lycoming on 1500 Aqua floats. It doesn't do much more than 80 mph on floats either! My gps usually shows groundspeeds between 69 all the way up to 109 depending on winds. I have a pretty flat prop also.

Good to hear from the rest of you Alaska guys. Great photo of the Kustatan, Dick. I wondered about flying over there for and landing in that mudhole for silvers. Next year. I used to go in there a lot with my C120, though I always landed on the grass strip further down. One day I took a friend over there and we got a our limit of silvers and it was kind of hot. I started out down the strip and went right out into the grass at full power. I cut the engine real fast then and came back and found a longer runway! It sure didn't perform like a cub, or even a T-craft for that matter.

I'm waiting now to take the floats off, but have to get good enough weather to fly to Willow to do it. Steve.

[Jim Libenow]

Floats, Spins

If you look at the log of Taylorcract accidents, spins with floats is right up there. The additional side area reduces rudder effectiveness. That is why cessna 206's have the strike mounted under the tail whenever they are on floats. Some taylorcrafts can have the same thing. I would not practice stalls anymore while you are on floats. Back in the 90's a favorate highschool teacher and friend lost their lives in an f19 on floats because of a spin. The addition of floats can dramatically change the aerodynamics. Do you have a climb prop on your plane? Mine has one a that I use whenever I am on floats and I only get 85-90 mph cruse.

[Robert Bradbury]

spins on floats

Jim,
I too have a sea plane prop, it is a Sen. 74 X 39 on a C90 .
I certainly do intend to not stall the plane again, but at least I know that using a blast of power will regain control of the aircraft . I will fabricate an additional ventral fin and insall next
year. This year is almost over for float flying here, I may have
six weeks left at best .

85-90 is faster than most of us are doing unless a tailwind was involved . I have seen 0 mph on the gps while flying into a low
level jetstream, and I have seen 135 ground speed one day flying with a 55mph tail wind . I would guess that I average
77 mph in no wind conditions .

What prop are you using ?

Robert

[Dick Smith]

speed on floats

Just came in from running a few speed checks with a Garmin 195 GPS. Running at 2350 rpm indicated on a C-85. Did 3 sets...2 times flying upwind(about 4 mph wind) and downwind on reciprocal course. One set in a crosswind, one way and then back on reciprocal. Also did 1 run going straight downwind just to see if my other downwind speeds were the same for my calculations. Took 56 readings during the 3 sets and 7 during the one separate downwind run. Averaging the 3 sets gave 86.51 mph. I only had about 6 gals in the nose tank. and about 40 pounds of survival gear and stuff. I'm about 190 with hipboots and floatcoat on...so the plane wasn't very heavy. But the wind was almost flat and this is the first decent bit of wx to come along, so I just got after it. Have had this plane since mid 70's and have always had other guys say that it was "fast". I know on wheels and skis it was often necessary to throttle back some to stay with other Taylorcrafts, when it had the C-65 with a Macauley 73 x 43. Everything being considered...I'll stick with "about 80 mph"!! Dick

addendum: On 10/17/04...ran some more GPS runs...nearly flat calm...Averaged out at 83 mph indicated.

[Robert Lees]

Jim is right: floats add a lot of side area ahead of the cg. The dorsal or ventral fin often added to some aircraft at the tail is to put some more side area back where it needs to be for longitudinal yaw stability.

In the power-off stall, prop wash over the fin/rudder is reduced, so that side area ahead of the cg can have a greater effect in trying to upset the aircraft. I would, however, expect the floatplane design to have been approved in terms of adequate longitudinal stability in the stall configuration (this is how aircraft designers determine the area of ventral or dorsal fin addition that is required).

Rob