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Seawind conversion

Old 09-20-2005, 09:33 PM
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76.ta
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Default Seawind conversion

I live by a pond that is smooth as glass most of the time. I can fly my electric planes there with no problems and am sure I can fly an electric off the water with no problems. Although I have some brushless 3-D planes, I have never converted a Glow plane to electric. Can you give me some suggestions of brushless motors, speed controls , props and light poly battery combinations? Building this plane electric will allow me to fly it whenever I feel like at the pond near my house instead of whenever I can get to a float fly plus I love the way it looks.
Thanks for any advice in advance.
Roy
PS This will be a strictly off-the-water plane.
REQUIRES: Engine: .60 cu in (10cc) 2-stroke
OR .70-.91 cu in (11.5-15cc) 4-stroke
SPECS: Wingspan: 71" (1805mm)
Wing Area: 676sq in (43.6 sq dm)
Weight: 10.25 - 12.25lb (4620 - 5555g)
Wing Loading: 35 - 41 oz/sq ft (106-127 g/sqdm)
Length: 56" (1410mm)
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Old 09-21-2005, 08:03 AM
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Walt Thyng
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Default RE: Seawind conversion

Give Kirk Massey at New Creations R/c a call. he'll give you very reliable information, good prices and quick service. Dave thacker at Radical r/c would be another possibility.

I'll be watching for more as I have my eye on the Seawind for a conversion, but haven't given it much thought. Since I already own several Maxcim motors that's probably the route I'll go. Actually Tom Cimato of MaxCim would be another good source of info.
Walt
Old 09-22-2005, 08:21 AM
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Greg Covey
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Default RE: Seawind conversion

I had hoped to get one of the initial Seawinds for a conversion article but Hobbico wanted the first wave for glow-powered reviews. Hopefully, I'll get to start one next month.

Without knowing the size of the pod dimensions, it is difficult to make the best choice. My preference would be to use an outrunner like an AXI 5320 motor or Actro 40-4 or 40-5 depending upon prop clearance. A 3-blade prop is a definite possibility here.
Old 09-22-2005, 11:07 PM
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gwh
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Default RE: Seawind conversion

Greg,

It appears that prop clearance is going to be around 13" dia. It looks like most outrunners will be hard to use. A 3 or 4 blade Vario prop might work. The is one plane that may have to use a inrunner with a low ratio gearbox and higher rpm to get the required thrust.

Wendell
Old 09-24-2005, 07:53 AM
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Default RE: Seawind conversion

Wendell,

Thanks for the information. I suspected as much and wanted to make suggestions with caution until I actually have one in my hands.

The geared Kontronik 600 brushless motor would work well here since the gearbox is in-line. I don't recommend using the 600 Brushless Set that comes with the Jazz-55 ESC thought due to the over-current shutdown kicking in prematurely around 45amps. I have had great success with this geared motor using a 13" prop with a Jeti 77-amp Opto ESC and a 6s or 7s Lithium pack of Kokam 3.2AH cells.

The [link=http://www.hobby-lobby.com/jetibrushless.htm]Jeti Phasor 45-3[/link] motor may work as well. On a 4 to 5 cell Lithium pack you could use an 11" or 12" prop. A 5s pack at 50 amps burst would provide around 900 watts.

Ideally, the more expensive Kohler Actro 40-4 would be perfect due to its thinner profile and near 2000w burst capability but Hobby Lobby is discontinuing sales of this motor due to its high price.
Old 10-05-2005, 08:08 AM
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c-grain
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Default RE: Seawind conversion

76,If you haven't bought the Seawind yet,I would recomend you take a look at the Northstar by BUSA.I just can't imagine how a plane with less than 700sq.in. ever ended up weighing between 10.25-12.25 lbs.The Northstar weighs about 6.5 lbs. and has 750 sq. in. area!Of course,you'll have to build it,but it's one of the best water planes ever designed and just perfect for electric conversion.Also, that pond had better be at least 150'long for a plane with that high a wing loading.I'm sory if I sound so pessemistic about the Seawind,but it seems at least 3lbs. too heavy to be a good flier.
Old 10-05-2005, 09:57 AM
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Greg Covey
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Default RE: Seawind conversion

The Seawind is heavy due to all the fiberglass and sheeted wing. It is a true scale model that you can see [link=http://www.seawindsna.com/]here[/link].

Although Laddy's Northstar is indeed a great design for the ages, the balsa kit should not be confused with a true scale model molded from fiberglass.

We'll see how it flies soon enough as I am now scheduled to convert one for Great Planes.
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Old 10-05-2005, 05:08 PM
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76.ta
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Default RE: Seawind conversion

Greg,
Do you have any idea what motor, battery, speed control, prop...that you are planning to try on the Seawind? I appreciate c-grain's input and I do agree with him on the weights but just can't get over the looks of the Seawind. Very few planes catch my eyes but this is definitely one.

Thanks
Roy
76.ta
www.hppilots.com
Old 10-05-2005, 06:43 PM
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Default RE: Seawind conversion

My four choices for extreme power would be the following:
[ul][*] Actro 40-4[*] AXI 5320/28[*] Hacker B50L geared[*] Kontronik 600 geared
[/ul]

An outrunner is always my first choice due to the simplicity and low maintenance. Since Hobby Lobby discontinued selling the Actro line due to high price, I will have to wait to have a Seawind in my hands to see if an AXI 5330 has any chance to fit. A smaller AXI 4330 may fit and keep the weight down with only a 6s Lithium requirement. We have many 10lb scale glow conversions using a 4130. It depends on how aerobatic you need the plane to be.

Since the Seawind does have flaps, they will help slow the plane for landing.
Old 10-06-2005, 09:05 AM
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c-grain
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Default RE: Seawind conversion

Hi guys,It seems that the real challenge with this plane is the prop diameter limitation.I tend to agree with Wendell.Most all of the large outrunners have low KV's and are designed to twist large props at lower rpm which will produce lots of thrust.With a 13"limit for the prop,you need to be turning well over 10,000 RPM in order to produce enough thrust for takeoff.If I were to try a conversion such as this,I'd start by using the new AXI 2826/8,a CC phoenix 60,12X8-13X6 on 3s-4s and shoot for 60A WOT for no more than 20 secs. or so.This combo will weigh around 1.5-2 lbs. less than the AXI 4130 system and that would lower the wing loading considerably!The Seawind is not an aerobatic plane,and needs to be as light as possible in order to overcome water drag to get up on step.I realize the smaller motor will be borderline on power for takeoff but is lighter and a lot less expensive to try.If it flies-great,it will be a lot more forgiving in the air and easier to land.If it won't get the plane off the water,then it will give you a real world idea of just how much more power is necessary.You can always use the motor and ESC. in another plane.Do you guys know what the empty airframe wt. is???If the Seawind is truly scale,then it probably has rather small control surfaces and I think you could save some wt. on radio gear.I remember when I was competing in scale contests back in the early 80's,the general rule of thumb for wing loadings was 29-30 oz. sq.ft. for models of 600-800 in. area.That was for land planes and the 30 oz. was absolute max!anything over that limit was considered an accident waiting to happen.I could be wrong here,but one thing I do know is "the lighter they are the better they fly"I will be very happy to find that the conversions you folks are working on do indeed fly well!! Good luck
Rich K.
Old 10-29-2005, 04:19 PM
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Default RE: Seawind conversion

Guys:
Keep in mind the projected weight of the Seawind is 10.25 to 12.25 lbs. Lets assume 100 w/lb for a sea plane to get off the water comfortably. Lets do the math. That becomes 1025 to 1225 WATTS! 1.025 to 1.225 kilowatts.

An axi 413016 on lipos can run at 1.0 to 1.2 kilowatts if propped properly. If you use 8s then you get the speed for a smaller diameter prop as required by the Seawind. or maybe.....wait a minute!

A blinding flash of Aeroengineering insight:

A four bladed prop!!!!! But made up of two regular two blade eprops. Has anyone ever tried stacking two props to make a four blader? It would need to be pinned or CAed or lock washered to keep a 90 deg. spacing. But it might work real good. You would need a custom prop adaptor to accommodate the double thickness of two prop hubs. And balancing should not be a major problem.

HEY, I might have something here. How cool would that look with two prop disks. Maybe paint the prop tips different colors. Selection of pitch at the required diameter, times two props will directly effect the torque requirement and so the current draw. WOW I think this may really be promising.

Thinking outside of the box is really fun. Come on you experts, what do you think?

best regards, Ray Foley
Old 10-31-2005, 11:31 AM
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P-51B
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Default RE: Seawind conversion

Why not just buy a four bladed prop? APC makes some.
Old 10-31-2005, 10:37 PM
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Mad Skill
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Default RE: Seawind conversion

How about an axi 5320/28 on 10S.
Old 11-03-2005, 04:10 PM
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dirkstr
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Default RE: Seawind conversion

Greg,

Jsut wanted to follow up with you about the seawind, my buddy and i were looking at doing the same aircraft. we have one on order and were hoping to get some insight as to the conversion from gas to electric.

we just are in the final stages of converting a 72" j-3 cub and have used an axi 4120/14 with a jeti 70 opt plus esc and the ultimate bec. we aer very excited about getting on the lake.

look forward to reading more
Old 11-10-2005, 07:33 AM
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c-grain
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Default RE: Seawind conversion

Hi guys,Has ANYONE out there built this plane and flown it yet,reguardless of power type-glo or E ??????????
Old 11-14-2005, 06:16 PM
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Default RE: Seawind conversion

It looks like a number of glow versions have been completed and successfully. Look in the seapalne forum here on RCU. It sounds like it's working out good. Greg - any updates? I was just going to start a big Cub float plane, but might wait and do this instead.
Old 11-23-2005, 10:03 AM
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gouda
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Default RE: Seawind conversion

Anyone made a progress yet? Mine should show up in a day or so. I'm going through the motor choices now. I have a Hacker C50-14XL, a AXI 2826/12 and a Axi 4120/14 available at the moment. I think the Hacker is a bit of overkill. I guess I'll run some motocalc numbers and see what happens. [8D]
Old 12-01-2005, 10:36 AM
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Default RE: Seawind conversion

gouda, have you made a decision about he engine youare going to use? my kit will be here tuesday and am really looking forward to hearing about your trials
thanks
Old 12-01-2005, 11:03 AM
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Default RE: Seawind conversion

dirkstr;

No I have not. The plane just showed up on tuesday and I have been away on business. My first order of business will be to make sure nothing is damaged as received. As far as the motors, I did try running it all through Motocalc. That was a disaster, Motor calc could not identify a motor/battery system that would work. I suspect because of the possible high wing loading. I don't think a AXI motor will work because it seems you're limited to about a 12" prop. Typically they need large diameter, high pitch props. It seems the slimer guys are using 3 bladed props with some good success. So that may be a possibility, so a lower ratio gear drive might be the way to go. If that holds true, the big Hacker would be the best choice. I'll do some moreMotocalc work and see what I can come up with.
Old 12-01-2005, 11:07 AM
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Default RE: Seawind conversion

Greg, any updates on your Seawind?
Old 12-01-2005, 02:44 PM
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dirkstr
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Default RE: Seawind conversion

HEY THANKS, LOOK FORWARD TO HEARING.

F Y I I DO KNOW THE FIRST NAME OF OUR UPS DELIVERY GUY, IN FACT HE STOPPED ME ON THE STREET THE OTHER DAY BECAUSE I WAS NOT HOME AND HE HAD STUFF FOR ME
Old 12-03-2005, 10:43 AM
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Default RE: Seawind conversion

Well, I unpacked my Seawind this morning. Everything was fine except some minor damage to the canopy. I have already written to Tower, so hopefully there will not be any issues with getting a replacement. Dang, this is a big airplane with almost no wing. It's really a nice piece of work. GP needs to hire a packaging Engineer however. Helloooo....

Cgrain, I don't believe a 2826 would even come close to flying this plane, I just to big/heavy with to high a wing loading. A 4130 would even be marginal IMO. But I'm going to do more motocalc work and see what I can come up with. Now at least I can weight the bits and have a better idea of the empty weight.
Old 12-03-2005, 10:44 AM
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gouda
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Default RE: Seawind conversion

Damage....
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Old 12-03-2005, 05:58 PM
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Default RE: Seawind conversion

I just got my Seawind this week. I am planning on putting an AXI 4130/20 in it with a 2 Thunder Power 3S 4200Mah packs. I believe I can save weight by not putting retracts or the fixed gear in. I really am looking for more input on what power system to use, especially the battery choice. Any thoughts?
Old 12-03-2005, 06:14 PM
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Default RE: Seawind conversion

6.47 lbs is what the basic airframe weighs without any landing gear. Add in a estimate of your radio equip and linkages etc and you can use motocalc to get a estimate of performance and motors required. I mentioned I would do that and post some results, just have not gotten to it yet, maybe by tomorrow morning.

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