HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jun 07, 2012, 01:41 AM
Fixed and rotary wing flyer
United States, CA, Newark
Joined Sep 2011
161 Posts
Steve, thanks for chiming in and providing a clear picture of what's going on. I'd be willing to try decreasing the incidence of the rear stab, but it's already glued onto the tail. Is there a clean easy way to get it off?

The hor stab slides into a cutout/slot on the tail where it is now glued. If I'm able to remove it, should I just shave out the front part of the cutout/slot opening - basically enlarge the leading edge of the gap to get the hor stab to have zero degrees of incidence relative to the wing? Then just use gorilla glue and let it foam up to fill in the gap?
fabric8 is offline Find More Posts by fabric8
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 07, 2012, 02:10 AM
Registered User
Joined Sep 2006
592 Posts
Steve,

Thanks for your analysis. Your insight is much appreciated.

Bob
bob93447 is offline Find More Posts by bob93447
Reply With Quote
Old Jun 07, 2012, 02:15 AM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,616 Posts
Happy to help, guys. fabric8, I'm not familiar with this kit but what you describe certainly sounds like it could work. If anyone tries this mod, I'll be eager to hear how it works out.
jetset44 is offline Find More Posts by jetset44
Reply With Quote
Old Jun 07, 2012, 09:17 AM
Registered User
DUNDAS CANADA
Joined Feb 2006
566 Posts
fabric 8.
With the location of the propeller right over CG, giving the down thrust will do nothing except push whole model down. The stabilizer should be between zero to -2 degrees.
LADDIE is offline Find More Posts by LADDIE
Reply With Quote
Old Jun 07, 2012, 01:40 PM
IAMCANADIAN
Grejen's Avatar
Canada, BC, Squamish
Joined Jul 2002
4,744 Posts
Interesting stuff. I've been flying my stock Seawind RxR off of grass and it's just fine by applying full power and full up to get it sliding then ease off both and manage rudder as it accelerates. A little bump in the turf or back pressure and it's off and flies well.

ROW is another story - skippity-do-dah. I was chalking this up to my own inexperience on water (ne'er mind my avatar).

Stab incidence is preset by that big slot and I'd not thought to try adjusting it although twice the stab was ..er... removed... in rough fashion. Next time that happens I'll adjust it for some negative incidence if the rest of the model survives it .

btw - Steve the wing on this beast is semi symetrical (there's an oxymoron). A very slight overall camber I would say. Also, the model flies well with the stock stab setting and, for my model at least, the elevator is trimed pretty much flat.
Grejen is offline Find More Posts by Grejen
RCG Plus Member
Last edited by Grejen; Jun 07, 2012 at 02:17 PM.
Reply With Quote
Old Jun 07, 2012, 06:08 PM
Fixed and rotary wing flyer
United States, CA, Newark
Joined Sep 2011
161 Posts
Quote:
Originally Posted by LADDIE View Post
fabric 8.
With the location of the propeller right over CG, giving the down thrust will do nothing except push whole model down. The stabilizer should be between zero to -2 degrees.
When you say it "should be", are you stating the kit should come that way? Or I need to make sure I modify the kit to be that way? Because per Steve and Bob, the Seawind has the stab at about +5 degrees of incidence relative to the wing. I haven't actually checked mine.
fabric8 is offline Find More Posts by fabric8
Last edited by fabric8; Jun 07, 2012 at 06:39 PM. Reason: I meant +5 - not -5 degrees
Reply With Quote
Old Jun 07, 2012, 06:12 PM
Registered User
Joined Sep 2006
592 Posts
Quote:
Originally Posted by fabric8 View Post
When you say it "should be", are you stating the kit should come that way? Or I need to make sure I modify the kit to be that way? Because per Steve and Bob, the Seawind has the stab at about -5 degrees of incidence relative to the wing. I haven't actually checked mine.
My 71" Seawind has the stab at +3 deg. relative to the wing. The Polaris, that Steve designed, has the stab at -2 deg. relative to the wing (and flys the way it should). Both Seawinds have the prop behind the CG whereas the Polaris has the prop well behind the CG.

Bob
bob93447 is offline Find More Posts by bob93447
Reply With Quote
Old Jun 07, 2012, 06:40 PM
Fixed and rotary wing flyer
United States, CA, Newark
Joined Sep 2011
161 Posts
I corrected a typo on my previous post. I meant to say "+5 degrees" - not "-5 degrees.
fabric8 is offline Find More Posts by fabric8
Reply With Quote
Old Jun 07, 2012, 11:54 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,616 Posts
Oops, I looked back at the note Bob sent me a couple months ago and it said he measured the stab incidence at +3 deg relative to the wing. I then said that because the wing has a semi-symmetrical airfoil, it probably had an angle of zero lift of -2 deg. So the total aerodynamic incidence difference is +5 deg. But if the thrustline is zero, that still means the prop slipstream hits the stab +3 deg angle of attack, which is probably what is causing the strong thrust-induced pitching this model exhibits.
jetset44 is offline Find More Posts by jetset44
Reply With Quote
Old Jun 08, 2012, 01:40 PM
Fixed and rotary wing flyer
United States, CA, Newark
Joined Sep 2011
161 Posts
So I flew another pack today to confirm the flight characteristics. The slight upthrust angle I've set with the motor doesn't cause the plane to dive or dip when I go from 1/3 to full throttle as its flying level.

I flew by a few times repeating this to make sure.

The plane just flies so nice now But if it will fly nicer with the stab setup with some negative incidence, I'm going to be even happier. I'll probably try messing with the stab after this weekend, as I'm really looking forward to trying it on the lake on Sunday.

FWIW, I get about 5:30 minutes of flight time, with my 1400kv motor with an APC 8x4e prop, and 2200mah 3S lipo. My cells are about 3.86v each when I land. I fly around varying throttle from 1/2 to full, and play around doing occasional loops, rolls, flybys and casual cruising. I can get 30min with my Bixler, but that's with soaring it high, cutting power, gliding, climbing back up again, catching thermals or wind, etc. Is 5:30 a decent amount of flight time for this sport plane? Should I try an 8x6e prop? I don't want more speed, just more flight time would be nice.
fabric8 is offline Find More Posts by fabric8
Reply With Quote
Old Jun 08, 2012, 06:52 PM
Registered User
Joined Sep 2006
592 Posts
Unless you have a wattmeter, you might want to approach the 8x6 gradually. Start by going to an 8x5 (EMP makes one) fly a few minutes, then check the motor temp. If its too hot to touch, then its too hot. If its cool, try the 8x6 with the same tests. If you don't spend too much time at full throttle you can probably use the 8x6 without frying your motor.

You're also being fairly conservative on your battery use. You can probably run them down to 3.7 volts/cell without worrying about damaging them. Below 3 volts is where they face death. I'd try adding about 30 sec./flight until you run them down to 3.7 volts (effectively storage charge).

Bob
bob93447 is offline Find More Posts by bob93447
Reply With Quote
Old Jun 08, 2012, 11:08 PM
Fixed and rotary wing flyer
United States, CA, Newark
Joined Sep 2011
161 Posts
Thanks for the suggestions, Bob. You were right about the voltage. By the time I got home and re-checked, they were reading over 3.9v each.
fabric8 is offline Find More Posts by fabric8
Reply With Quote
Old Jun 08, 2012, 11:11 PM
Registered User
Joined Sep 2006
592 Posts
Battery

Sounds like you should be good for 8-10 minutes. I once got close to 15 on mine with a 2100 mah battery but it ran out of juice over the lake and I had to swim for it. I charged the battery as soon as I got home and its been no worse for the wear.
bob93447 is offline Find More Posts by bob93447
Reply With Quote
Old Jun 11, 2012, 01:00 PM
Registered User
BJM-Maxx's Avatar
Joined Sep 2007
643 Posts
Servo failure in flight

My Seawind has been my cottage plane for over 3 years now. Early on there were some nasty failures as the stock ESC burned up causing a crash, the stock motor was always quite feeble, not like the videos show. The stock servos gave up quite soon as well. That was year one. Since then it has been very reliable and I even did some FPV flights with it.

Yesterday I discovered that the shed I keep it in had leaked water in my plane, the electronics were in water for ~ 2 weeks. I drained and dried it and the plane seemed fine except the elevator servo made a weird rhythmic clicking unless it was active. I almost flew it as is. I decided to swap the rudder and elevator servos (my spare parts were all at home). I flew 6 batteries through it with not issue. On the last flight just before the last turn to land, the plane swung full left rudder and stayed there. It was harder to fly but I landed and had to use ailerons to steer and get it to shore. The servo could be forced straight and it would just snap left after a brief delay. I got lucky.

I noticed that the Seawind has almost no rudder to roll coupling. Most planes would be a real fight to keep it level but the Seawind was quite easy to control even with the jammed rudder.

It looks pretty rough after all the abuse but still flies nicely, I have always enjoyed this plane.
BJM-Maxx is offline Find More Posts by BJM-Maxx
Reply With Quote
Old Jun 11, 2012, 09:17 PM
Registered User
Joined Apr 2012
9 Posts
How big a motor is too big?

On my Seawind EP RxR the stab incidence is -3 degrees. I have found pitch stability to be influenced more by CofG location than up- or down-thrust angles on the motor. This is probably because I am flying the model heavy, at 32oz. When the CofG is moved further aft than 28mm is where I really start noticing pitchyness with throttle changes.

My motor mount front plate seperated on my last flight in October of 2011. It was still glued in one corner, but for the most part it was wedged in place by the cowling and kept on providing thrust. Although the prop had some serious down angle there was no prop strike. (The scars on the turtle deck are older war wounds.) Other than the strange sound, handling was nominal.

This plane has taken a lot of abuse as a test platform and it keeps on flying. During my first season with it I've reinforced every known structural weak point, including the motor pod. In April I flew it with a custom mount and AEO Tech CR28M contra-rotating motors. Climbed like a bat out of hell with no torque roll or P-factor. For 2 flights. The front bell spit 5 magets on the second flight. AEO Tech has a reputation for dubious quality control. I won't be using their products again.

Next up I'll be trying Himax 2816 contra-rotating motors and a custom 60 inch wing. The increased surface area will keep the wing loading at around 20oz/sq.ft. but my biggest concern is that this setup may be too top heavy. I'm considering increasing dihedral on the wing, as well as using 2 batteries to bring the centre of mass down.

FWIW I've had some fun testing this in RealFlight with a custom profile integrating a 60 inch wing and a 0.30 gas motor weighing twice as much as the Himax. Makes for some very amusing slow flight.

So, what's the biggest motor tested on the Seawind EP?
FrancoisSabourin is offline Find More Posts by FrancoisSabourin
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Seawind By great Planes postusaf Fuel Plane Talk 9 Jun 03, 2012 07:08 PM
Rant Electrifly C-50 Brush ESC by GREAT PLANES guapoman2000 Power Systems 24 Mar 02, 2009 05:32 AM
Question Seawind by great planes postusaf Waterplanes 1 May 15, 2006 12:32 AM
Great Planes ElectriFly PT-Electric Trainer Kit 56" markmm Electric Plane Talk 14 Oct 04, 2005 04:08 PM
F/S Electric Cub by Great Planes Wing 59" Butch777 Aircraft - Electric - Airplanes (FS/W) 2 May 25, 2005 05:58 PM