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Old Feb 13, 2009, 08:30 AM
We shall serve the Lord
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United States, TX, Kingsland
Joined Sep 2005
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Swice - The motor you've listed is heavier than my 50-55-500, has a very low kV rating of 250, and your motor takes a 20" diameter prop. Even with a 10 cell pack, you are going to need a lot of prop to load this motor. There is a 3-blade 13.5x13.5 that will barely fit the airframe that may come close. Your modified 13.5x14 may be a better choice. The Seawind motor pylon will flex on hard landings, so you may have blade strikes with the 13.5" prop.
Mike McD
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Last edited by kingsflyer; Apr 08, 2009 at 08:50 AM.
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Old Feb 13, 2009, 03:03 PM
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Joined Jan 2009
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I am new in this rc and make many mistskes. I was 73 years old when I started the hobby so I am prone to not supplying all the facts when I have a question or make a statement. The 13.5 x13.5 is a 3 blade prop. Thank you so much kingfish. God bless you chas swicegood
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Old Feb 14, 2009, 08:39 AM
We shall serve the Lord
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United States, TX, Kingsland
Joined Sep 2005
5,136 Posts
Chas,

Glad to help. I flew my 1st RC plane in 1954 when I was 5. My Dad had a single channel plane and he let me hang on to the push button for a bit. I started flying RC for real in 1965, so I've been at this for "over" forty years. After turning 60, my forgetter started working better than my rememberer. CRS is a terrible thing (Can't Remember Stuff). But I've found that folks here on RCGroups are very helpful and don't mind answering questions so I get a lot of information on lots of topics. I learn something new every day!

Blessings,
Mike McD
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Old Feb 14, 2009, 03:27 PM
Ozzie Express wiggy pilot
SON OF PALEFACE's Avatar
YANKALILLA , SOUTH AUSTRALIA.
Joined Nov 2002
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I have about the same history , turned 64 in January .....been flying propo since 1972 Down here we call that "The Here After Disease".....thats when you get to the shop and say........
What did I come..."here after"
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Old Feb 21, 2009, 09:52 PM
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Fairfield, Iowa
Joined Dec 2008
6 Posts
Dear Kingsflyer,
I'm building a GP 71 Seawind with electric conversion. I'm also using retracts. Do you know why they recomend diabling the retracts for water flying. Granted the front retract door must be a close fit and seal but it would be neat to drive the plane in the water, retract the gear and fly and do the reverse at the end. The real one can do that, we should be able to do that with the model. What do you or anyone think?
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Old Feb 22, 2009, 08:05 AM
We shall serve the Lord
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United States, TX, Kingsland
Joined Sep 2005
5,136 Posts
I'm not sure, but I think there would be several issues with the retracts that would need to be solved before you could operate off of water. The front gear door would become an important part of the hull and it would not only have to form a water tight seal, but be able to take the physical abuse of water flowing past, and it would have to provide enough structural strength to help lift the hull in the water.

Once you solved the door problem, you would then need to solve the problem of sealing all the hull penetrations when the retract "stuff" makes its way from the hull to the retracts.

Then I think you would have to address the issue of protecting the retract gear and mechanisims from rust and fouling.

If the retracts were to fail and come down in flight, you would not be able to make a safe landing on water without damaging the plane usless you also have a hard surface runway nearby.

I don't think it would be impossible, but it would be a lot of work to make the system work safely and reliably.

Let us know how it works out and please post some pictures and video of your Seawind.

Mike McD
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Old Feb 22, 2009, 08:50 AM
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Fairfield, Iowa
Joined Dec 2008
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Thanks Mike for your reply. Your thoughts on this are what I thought. Maybe not worth the trouble but I'll consider it as I build.
Anyone else have some ideas?
Robert
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Old Feb 24, 2009, 08:58 PM
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Fairfield, Iowa
Joined Dec 2008
6 Posts
Dear Mdennis,
I'm building a 71" GP Seawind with electric power and retracts. I'm considering various motors and have studied your Motocalc posts. I wonder if you would mind doing a Motocalc on the Ramfire 50-55-650 motor with the 71 Seawind. Could you do it with the 13x8 prop and also a 3 blade 13.5x13.5 prop or what ever prop would be appropriate. I would guess my plane will be 10 to 12 lbs with retracts. If you have the time to do this, thanks for your help in.
Robert
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Old Mar 01, 2009, 04:15 AM
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Wald, Austria
Joined Nov 2001
85 Posts
Flies great !

Some days ago I had the maiden flight with my Seawind starting on snow.
If the snow is powder-like it gets off very easy, but if it's heavy-wet snow it is neccessary to pull full elevator (as Kingfisher said also on water).

The Seawind flies really great, has a great speedrange and can get very fast.
It looks very impressive and also loops and rolls are no problem.

This is my final setup:
Kontronik KoraTop 20-16 (460 kv)
Kontronik Jazz 80-6-18 BEC
APC-E 14x8,5
XCell 3900 6s
Max. current about 50A
Weight 4100g

Very impressive model !

Thanks for all advice !
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Old Mar 04, 2009, 06:53 AM
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Joined Jul 2004
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Hi guys well I finally got to take home my sea wind on Saturday night and spent the next few hours fitting the hinges to the flaps and ailerons. I found a picture of a full sized seawind that confirms my suspicions that the step is way too far forward and should be just infront of the C of G, this makes Great Planes out buy about 3", this in turn would cause the model to drag it's bum in the water and rotate prematurelty and richochet like a pig on landing unless dragged in on the stall.....all in all not pretty! I also noticed that the hull is rediculously thin around the step which is right where the most abuse takes place, to help overcome this and the dreaded splitting of the seams, I have laid some 3k carbon cloth about an inch up the side walls an accross the bottom of the hull. To overcome the dodgy step location I will be extending the step 3" rearward with blue foam and have laid carbon cloth an additional 1" behind the new step so as not to create a stress riser.
To help reduce the requirement of lead in the front I will be using a short pushrod on the rudder and be remotely driving the elevator with a pushrod and be mounting both servos in the engine pod.

I have also decided to use mechanicle retracts because there sitting on the shelf and heaps lighter than the robarts although they do look pretty trick, just not the price tag! I'll also be fitting nose doors so I can taxi into the water pull the gear up and take off and visa vera after landing..... it's going to be relatively easy to do and will really add to the scale appeal.
last night I made up my blue foam step extension that was rough cut to size on the bandsaw and glued it in place with silicon adhesive. The gaps were filled with lightweight filler and will be sanded to match today. In order to fit the mechanacle retracts, the original mounting blocks in the wheel bay had to be removed to allow the retract to fit up inside the well with a new mounting plate and some minor glass work still to be done.

Being a stickler for a neat and tidy model I absolutely hate with a pation the rudder servo hanging out the side to get drowned in the spray. Given the thickness of the rudder my solution was to drive the rudder via the leading edge half way up the rudder with a 2-56 pushrod and clevise, the servo will be mounted inside the fuel tank bay along with the elevator servo. This not only makes things neater but will alos help to address the tail heavyness that most other builders have noted.

cheers Rossco.
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Old Mar 04, 2009, 12:22 PM
Ozzie Express wiggy pilot
SON OF PALEFACE's Avatar
YANKALILLA , SOUTH AUSTRALIA.
Joined Nov 2002
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Good work Rossco , these mods are in line with my thoughts also , will be really keen to see how the step mod does (video)
Ian
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Old Mar 04, 2009, 12:34 PM
Electric Airplane Junkie
bhchan's Avatar
United States, CA, San Mateo
Joined Jun 2000
5,597 Posts
Yes, I would like to know how the extended step works.

Brian, an EAJ
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Old Mar 04, 2009, 08:45 PM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
1,137 Posts
Quote:
Originally Posted by vedoham
Dear Mdennis,
I'm building a 71" GP Seawind with electric power and retracts. I'm considering various motors and have studied your Motocalc posts. I wonder if you would mind doing a Motocalc on the Ramfire 50-55-650 motor with the 71 Seawind. Could you do it with the 13x8 prop and also a 3 blade 13.5x13.5 prop or what ever prop would be appropriate. I would guess my plane will be 10 to 12 lbs with retracts. If you have the time to do this, thanks for your help in.
Robert
I think you will find your answers back in posts 36, 38 and 99. Your plane weighs a little more, but the thrust the motor puts out will be the same. The Rimfire with the 2 blade 13x8 prop puts out about 119 ounces of thrust and your plane will weigh 160 to 192 ounces, (10 to 12 lbs). It will fly, but it just won't accelerate quite as quickly. The additional weight also means your wing loading will be higher, so you will have to be going faster to get it off the water.

Mark
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Old Mar 05, 2009, 09:22 AM
We shall serve the Lord
kingsflyer's Avatar
United States, TX, Kingsland
Joined Sep 2005
5,136 Posts
Nice looking mods Rossco. Looking forward to your takeoff reports and hopefully some videos.
Mike McD
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Old Mar 05, 2009, 03:41 PM
Ozzie Express wiggy pilot
SON OF PALEFACE's Avatar
YANKALILLA , SOUTH AUSTRALIA.
Joined Nov 2002
5,234 Posts
DONT forget the RED Corrosion X........
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