Bob93447

Good luck! And don't hesitate to ask if you have questions. There are plenty of people both here and on the RCG thread that have had experience with converting the Seawind to electric.

ALO 111

Thank you , some suggestions as to what motor , esc and lipos will be very welcome as i am dumb in the electric game. I really dont want it underpowered.

Bob93447

What is the altitude of the body of water you're going to use? That makes a difference in what to recommend. How clean is it that tells you how much CorrosionX you will need for the receiver and esc.

Bob93447

If you don't want to be underpowered, the key thing is remember that you are pretty much constrained to a 13" diameter prop. Additionally, wood props pretty much get shredded by the water spray.

So, my recommended power setup is:

1) 13x8 Standard, not electric, APC prop
2) 540/- KV Scorpion or Hyperion high efficiency motor (4xxx class of motor)
3) 100 amp Castle edge controller I particulary like the edge series because you can tie a disable switch to one channel of the receiver. This allows you to have a method of arming and checking all functions of the aircraft before you close the hatch, then disable the motor via the controller until you are finished.

4) 6s, 4000 mah battery. 20C is sufficient.

This setup should produce about 1200 watts at 500 meter altitude, or about 120 watts/lb. for the airplane and a pitch speed of about 78 mph. You could go to a 13x9 for more speed. I would stay away from higher pitch props until you get familiar with the aircraft because of prop stall issues.

There is a motor calculator on the Castle creations website that will let you fine tune motor/battery/esc combinations.

If you want to save money on the motor you could probably use something from HobbyKing but you probably will pay in terms of weight and efficiency.

There appears to be an esc heating issue for flights longer than 5 minutes which might be solved with a YEP (freewheeling) esc but I have no experience with these esc's. I am considering using a small computer fan.

Bob

JoeR

My Feedback: (2)

This is the motor I bought for my conversion. I haven't flown it or even installed it yet so Ican't tell you how well it will work.

http://www.hobbyking.com/hobbyking/s...dProduct=22035

Bob93447

Should work. Why don't you test it on a 13x8 with a 6s pack and see what rpm you're getting. You can plug the number into the Castle calculator and see how much thrust you're getting and what sort of pitch speed.

They did not have the NTM motor on the Castle calculator but they had a Turnigy SK5055-5 (580 KV). It looked good on 6s with a 100 amp esc.

ALO 111

I am at 1350 m and its clean fresh water .

Bob93447

Hopefully you're starting with a fresh airframe that can be configured for water only flying. Because the Seawind has such a high wing loading, my recomendations are to keep it as light as possible given the altitude, 1350m, that you're flying (I'm at 1900m).

The weight goal, with batteries and ready to fly, is <4.6 Kg (10lbs).

The motor should be capable of >1200 watts for at least 15 seconds (takeoff). Without fixed landing gear, the Seawind is very aerodynamic and requires much less than full power to fly. Ideally, the motor will weigh < 310 gms but the 350 for some of the turnigy motors is not out of the question. Motor should have a KV>540.

With a 75 or 100 amp esc, and a 6s, 20c, 4000 mah battery the setup should be capable of spinning a standard APC (not an e-prop) 13x8 prop at >10,000 RPM. That will give you a pitch speed of 80mph, a an actual top speed in the neighborhood of 65 MPH and a static thrust of >4200 gms. If you want more speed, you can prop to 13x9 but higher pitches run into prop stall issues. I would recommend going to a higher KV motor before going to very high, >9", pitch props.

I would recommend going to www.castlecreations.com to use their motor calculator site.
I have also started using the Phoenix edge controller in my Seawind. It has an independent throttle cut function, a huge safety factor in my mind insofar as you are in front of the prop after you hook up the batteries and while you are securing the canopy for flight.

Bob

ALO 111

Thanx for all the info really helps a lot, going to go do some pricing.

Bob93447

Good luck. Glad to answer questions.

Bob

Bob93447

Taming the Seawind

Up until two weeks ago my Seawind had a terrible issue with porpoising. A typical takeoff consisted of three progressively increasing jumps off the water; the only way to get airborne was to substantially reduce power on the third bounce, let the beast stabilize, and then add enough power to start a gradual climb before losing altitude and hitting the water.

The formula that works for me is the following;

Alignment - align the horizontal stabilizer to about 3 deg negative to the wing incidence. Align the motor to the horizontal stabilizer. A quick note here, with this motor alignment the motor shaft comes out in the bottom half of the cowl opening. When I add the spinner back I will try to realign the cowl. For now it just looks ugly.

Power A motor/ battery/ prop combo that provides > 1000 watts on takeoff and a pitch speed of > 75 mph

Prop - A pitch of < 9". With a pitch of > 9", the prop is coming "unstalled" at about the same speed as the aircraft lifts off, providing a large downward force on the nose as the prop gains "traction". This is for a 13" diameter prop. Smaller props will require less pitch.

Flaps - about 50% for takeoff, 100% for landing.

Insofar as I get few chances to fly my Seawind, my unscientific approach was to apply all of the above simultaneously so I can't say which has the biggest impact. Together they have turned takeoffs into a non-event, requiring almost no up elevator to leave the water.

JoeR

My Feedback: (2)

Since it looks like this thread may be getting a little activity... I'll ask-  anyone have an extra wing joiner?  I need one for my GP Seawind.  Thanks

HUNTERANDJEFF

Joe,
Do you have a bandsaw or know someone that has one? Bandsaws cut through aluminum like butter - no kidding. Anyway, if you know someone that has a seawind have them pull the wing joiner out and trace it. Now use that patterrn to make yourself a new wing joiner. Sand it smooth and it will work better than the stock one. The stock one was a bit narrow (not in thickness) but in depth so alot of guys were complaining about their wings being a bit loose. If you make your own, you can correct this and stock aluminum is cheap at lowes or home depot.
I think there are alot of people that will pull their plane apart and trace that joiner for you. They could just send the pattern to you in the mail.
Jeff

JoeR

My Feedback: (2)

Jeff, thanks. I don't know anyone close with a Seawind. I think the only one I've ever seen in person is the one Ihave. Someone did provide me with dimensions for the joiner and I made one out of wood to confirm. I bought a piece of aluminum at Hoome Depot but its .125" thick rather than the .100" (if I remember correctly) of the joiner. So I'm most hesitent about commiting to filing down the thickness of the joiner after I've got it cut out. I know aluminum is soft but I'm not sure its going to be manageable to take it down to the right thickness. Still, Iwill if Idon't have an alternative whenI get to the project.

ALO 111

Bob how do you think a power 60 will cope ?

[email protected]

Hi Bob and ALO and other Seawind enthusiasts,

I was recently near water in the 1000 Islands and was able to get my Seawind off the water. This is the eighth year I’ve campaigned this airplane and it shows all the marks from climbing the learning curve. I’ve put a video of one flight on Youtube at: http://www.youtube.com/watch?v=C0KWAUHwrZ8 . You get to see the whole Seawind saga: the tendency to porpoise on takeoff, which is suppressed by 100% flaps and up elevator, a successful touch and go, and a splashy landing. Hope you enjoy.

Tony Loomis
AMA #76638

Bob93447

Nice video Tony. What engine and prop are you using?

When mine used to porpoise, the bounces were roughly 10' into the air and got progressively higher. Unsuppressed, the plane would eventually end up nose first into the water.

Bob

[email protected]

Hi Bob,

Thanks for the comment. Likewise on being in the water. I have a >15 yr OS FS91 with a Graupner 3 blade prop which I may(?) have cut down. I think the prop is 13x6 but I can't check it right now.

Bob93447

ALO 111

The Power 60 is only 400KV so you will need to go to an 8s battery to get enough rpms to make it flyable. I would resist the temptation to use a high pitch prop until you get accustomed to getting your Seawind off the water. A 13x8 APC or G-sonic prop should do fine. The 13" prop diameter limit of the Seawind really limits the amount of power you can get out of the motor, but the low current draw means you can stick with 20C batteries. If you feel the need for speed you might try a 13x9; going to a high pitch might make takeoffs "touchy". If you haven't purchased the motor yet you might consider something on the order of 600 KV with a 6s battery or 800 kv with a 5s battery (4s Min).

Basically, the stall speed of the Seawind is on the order of 40 KPH +/-. You want to prop it so that it can fly at least twice the stall speed. Assuming the plane will fly at roughly 80% of it pitch speed, then a 13x8 with a Power 60 motor and an 8S battery setup should fly at >90 KPH.

Bob

jrf

My Feedback: (551)

Bob, correct me if I am wrong, but I get a pitch speed of 95 Mph (not Kph) from the 8 cell 8 pitch setup you describe. It seems to me that a 6 cell, with a pitch speed of 71 Mph might work OK in the Seawind. I flew mine on a glow .61 with a pitch speed of 66 to 72 Mph and it flew very well.

Jim

Bob93447

Jim,

I'm quoting numbers from e-calc on the Castle Creations website. The Power 60 is a 400 Kv motor and needs more cells to get reasonable RPM. Also, ALO 111 is flying at 1350 meters, about 4500', and may want a bit more speed. When I use the Castle calculator for the Seawind, I never use a battery voltage higher than "normal". Typically one loses a bit of voltage getting to the motor due to the long leads necessary to get the battery power up to the motor. That said, I get an rpm of about 9600 using the Power 60 and a 13x8 APC prop. That gives a 76 mph pitch speed or 122 km/h. At best I figure flight speed to be about 80% of pitch speed so at takeoff the aircraft will have a max speed of about 61 mph. I'm flying off Lake Tahoe at 6230' using similar number for what I consider to be a reasonably comfortable flight envelope. Backing off to 6s only gives a 59 mph pitch speed or about a 48 mph top speed which seems a bit low to me. But the key assumption I'm making is to only use normal voltage, vs full voltage, when doing the Seawind Calculation because of the long electrical leads. This assumption is pretty well supported by my own test data from my Seawind.

Bob

jrf

My Feedback: (551)

Bob:

I will not argue with your analysis. Given the altitude and the long leads, I suspect your mph numbers are closer than mine.

The primary reason for my post, though, was your use of Kph instead on Mph, which made your numbers look unrealistically low. As I am sure you know, 90 Kph is about 54 Mph.

Jim

ALO 111

I Also flew mine on a 61 glow for a while and then a 91 2 stroke, very fast. Iam just trying to cut costs a bit as the some setups get very pricey. My reason for going to electric is the drop in weight plus the added advantage of no having a motor stall in the middle of the dam

Bob93447

ALO 111

A good setup to start with for "electrifying" you Seawind is to look at the prop you were flying it with using either the .61 or .91. If you can, bench test your favorite setup to get an RPM for that particular prop. Use the Castle calculator to tell you what battery you need to achieve the same performance with your Power 60. It shouldn't cost too much for a set of batteries. For the 8s setup I suggested you can put two 4s batteries, 2700 mah capacity, in series to achieve 8s and the price for both batteries is < $40 US plus shipping from HobbyKIng. That pack will give you 6-7 minutes of flying.

Bob

ALO 111

Just wondering with the battery in the hull are you guys opening the canopy every time to charge or and do you use the hatch behind the motor for access to the wires and speed control?