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Old Sep 27, 2008, 02:01 PM
Time for another motto!
Utrecht, The Netherlands
Joined Jul 2006
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@onewoo: you will very likely need an elevator in the propstream, to counter the nosedown moment of the off-axis prop.
@Thomas: you will need to increase the downthrust of the prop, and probably also the incidence of the horizontal stabilizer. The big problem with these types of planes is the off-axis thrust that needs to be compensated somehow. It will be much easier to get another motor (or 4 blade prop) than to change the thrust position/angle.
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Old Sep 27, 2008, 02:54 PM
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Sweden
Joined Mar 2006
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Quote:
Originally Posted by walt b
Tomas
Have you considered a three blade prop?
Walt
Good idea! What 3 blade size correspond to a 2 blade 8"x3,8" and where can I buy them?
/Tomas D.
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Old Sep 28, 2008, 09:18 PM
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Joined Jan 2007
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Quote:
Originally Posted by lebardemelon
Hi Larry,
Is it still possible to provide "ScaleAndTile3" overseas...? I checked that the dédicated thread is moreless outdated (2007...)
Thanks
Eric
It is not outdated. There was simply nothing more to say, as there were no new developments, except for a lot of people signing up for it.

Just follow the instructions at about message #41 in the ScaleAndTile3 thread, and you'll get it, as long as the Internet con be found in your location. You are here, so I deduce you've found the Internet. ;-)

Cheers,
Bill Segraves
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Old Sep 28, 2008, 11:21 PM
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Seattle, WA
Joined Jun 2002
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Tomas,
I hate to say this, but I'd be a little worried an 8" prop would cause pitch problems on the 100% Polaris--but on a 75% Polaris I'd be VERY worried. That prop is just too big for this model. I think it will put the thrust line so high that it will cause lots of trim problems. It'll no doubt fly, it just probably won't handle well since you'll constantly be fighting the trim. If at all possible, I'd suggest using a different motor that can spin a lower diameter prop. This is exactly why I picked the Grayson motor for my model--it only spins a 6" prop, which is quite small for the 100% model and thus results in excellent handling qualities.

If you do try this motor, you'll need to add more downthrust to reduce the pitch change with throttle. I used 2 degrees nosedown on my model, and you'd probably want at least 4 degrees if not more on your smaller model with the 8" prop.

Steve
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Old Sep 28, 2008, 11:28 PM
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Seattle, WA
Joined Jun 2002
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Quote:
Originally Posted by onewoo
Has anyone used just rudder and elevons rather than elevator, rudder and ailerons?
You could modify this design to fly with just elevons and it could certainly work, but I think you would lose a lot. Having the rudder AND elevator in the prop blast gives this model excellent controllability, and is a big part of the reason this model is such a joy to fly. With elevons only, you'd want to delete the horizontal tail, move the vertical tail forward, and make the vertical tail bigger to compensate for the loss of moment arm. This would probably result in an airplane that flies OK but has significantly less pitch stability and pitch control than the original design--you certainly couldn't horse it around in the air and on the water like I did in the video at the beginning of this thread.

Steve
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Old Sep 28, 2008, 11:30 PM
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tpfing - Cool look on that wide nacelle! Definitely gives the model a general aviation look, sorta like a Seawind.
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Old Oct 03, 2008, 09:23 AM
Retired and Lovin' it!
United States, KY, Sturgis
Joined Jul 2007
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Steve, this is really a super little airplane. Maidened it this morning. It was really a total non-event. Take off from grass is great. Tracks straight as an arrow. The lift off is very realistic looking and climb out is nice. It cruises around at 1/2 throttle with no problems. I must have shot at least 6 touch and goes. I love being able to do touch and goes in the grass in my back yard. Low and slow is a dream.

The power setup is as follows:

Motor - Grayson 2212-10
Prop - APC 7x5
ESC - RichModels - 18A
Battery - Electrifly 1500 mAh 15C
Receiver - GWS 4 channel
Transmitter - Hitec Optic 6
Weight ready to fly - 17 oz.
Just in case you can't tell, I'm all

Now I guess its time to put on a finish. If I don't chicken out, the finish will be a sort of Coast Guard scheme with white base color and orange trim and black accents.

Tony
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Old Oct 03, 2008, 03:05 PM
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Seattle, WA
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CONGRATS, Tony! Very glad to hear it flew well for you. And 17 oz is a very nice low weight!

Can't wait to see how it looks with that Coast Guard scheme.

Steve
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Old Oct 03, 2008, 04:55 PM
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Northwest Ohio
Joined Jan 2002
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Quote:
Originally Posted by tpfing
Steve, this is really a super little airplane. Maidened it this morning. It was really a total non-event. Take off from grass is great. Tracks straight as an arrow. The lift off is very realistic looking and climb out is nice. It cruises around at 1/2 throttle with no problems. I must have shot at least 6 touch and goes. I love being able to do touch and goes in the grass in my back yard. Low and slow is a dream.

The power setup is as follows:

Motor - Grayson 2212-10
Prop - APC 7x5
ESC - RichModels - 18A
Battery - Electrifly 1500 mAh 15C
Receiver - GWS 4 channel
Transmitter - Hitec Optic 6
Weight ready to fly - 17 oz.
Just in case you can't tell, I'm all

Now I guess its time to put on a finish. If I don't chicken out, the finish will be a sort of Coast Guard scheme with white base color and orange trim and black accents.

Tony
I was wondering how the 2212-10 would do on the Polaris. That's a potent combo with the 7/5 prop. Lots of thrust which might be a good match for this plane.

Plus, with the 2212-10, you could drop down to a 1000 or 1320 mAh 20C battery and save even more weight. Steve or Tony, do you feel it would balance OK with a 3 oz. battery?

Congrats on your successful maiden!

Scott

www.ModelAero.com
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Old Oct 03, 2008, 05:08 PM
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DUNDAS CANADA
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Steve.
I agree 100% with everything you said her.
Laddie.
Quote:
Originally Posted by jetset44
You could modify this design to fly with just elevons and it could certainly work, but I think you would lose a lot. Having the rudder AND elevator in the prop blast gives this model excellent controllability, and is a big part of the reason this model is such a joy to fly. With elevons only, you'd want to delete the horizontal tail, move the vertical tail forward, and make the vertical tail bigger to compensate for the loss of moment arm. This would probably result in an airplane that flies OK but has significantly less pitch stability and pitch control than the original design--you certainly couldn't horse it around in the air and on the water like I did in the video at the beginning of this thread.

Steve
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Old Oct 03, 2008, 06:11 PM
Retired and Lovin' it!
United States, KY, Sturgis
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GG, my Electrifly battery weighs about 5 oz. I also have built some extra weight in the rear end. I don't think there would be any problem balancing with a 1320. There is a world of room in front for battery placement. I really love the 2212-10. I have three of them right now. I used one on my 6mmflyrc Skyray pusher and I have one on my Shumate F-18. My planes are not speed demons but they fly very realistically. With a 20 Amp ESC and a 1500 mAh battery, nothing gets hot. In fact, things are just barely above ambient temperatures. So, my planes are easy on my nerves and the power setup is easy on my equipment. Win-win.

Incidentally, I got in two more flights today. This morning in just a slight breeze, you can just hang this plane in a high alpha hover. This wings will rock back and forth and you just balance the drag against power and she just hangs there. Amazing. And touch and goes on the grass are a 'hoot'. Maybe I should say 'slide and goes'.

Tony
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Old Oct 03, 2008, 11:02 PM
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Seattle, WA
Joined Jun 2002
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Laddie - Thanks for chiming in. Didn't you design a tail-less North Star-like seaplane some time ago? I think I remember seeing it but can't remember where...

Scott - I'll agree with Tony--the Polaris should balance just fine with a 3.0 oz battery. The 5 oz battery in my plane is still quite a ways from the nose, so simply sliding the lighter battery all the way forward should do it. And if you used a lighter motor like the Littlescreamers Super Park Jet, it would balance even easier with the lighter pack.

Tony - Boy, you're making me itch to get my Polaris out again (haven't flown it since I shot the video). I had a blast doing "slide and goes" off the grass at my local schoolyard, too!

Steve
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Old Oct 04, 2008, 05:33 AM
everything with RC
Brest..."grand ouest"
Joined Nov 2004
156 Posts
Hi,
I will start soon the 75% Polaris. What do you think about an edf approach? with GWS 55 or GWS 65?
According to you, how high should we have to place the ducted fan?
Thanks
eric
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Old Oct 04, 2008, 09:18 AM
Retired and Lovin' it!
United States, KY, Sturgis
Joined Jul 2007
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This is such a fun flying airplane. I'm really surprised that it is not getting more attention here on RCGroups. I realize that not everyone is interested in float flying but you don't need water, just grass will do fine. I had been flying pusher prop jets but I really missed not being able to do touch and goes. And this airplane gives me that opportunity plus it just handles so nicely. Also, with its jet-like looks, well, you get both worlds.

I've included some photos to illustrate the range of placement for the battery pack. There is at least 10 inches fore and aft of allowable movement.

Last two photos illustrate my treatment of the nacelle. And I haven't even added the tip floats yet!!

Tony
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Last edited by tpfing; Oct 04, 2008 at 09:35 AM. Reason: spelling
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Old Oct 04, 2008, 09:31 AM
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Looks great Tony!

It WILL be getting more attention around here for sure!
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