skywagn180

Question...Any wing rock at half the wing loading with the Polaris? I just envision this much cleaner, slower and more friendly water handling with a moderate V on the main hull and aggressive V on the tip floats. I see all three surfaces having significant steps or tapering to a point like almost all real flying boats. I see a touch of toe in on the tip floats too. I really think your tip dragging issues would go away too. Has anyone at all tried V hulls on the NS or similar platform?

aa1a

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I suspect that if you went on any thread, Kaos thread, Ultra sport thread, Spitfire thread etc. and proposed ten radical "improvements" to the design, you would get a chilly reception. People on the thread are there because they are fans of the airplane. When I go to a float fly, no one cares about an apprentice on floats but everyone wants to see the Northstar fly. They don't care about wing rock or prop clearance. My 2 cents
Jim

Charlie P.

I'm with aa1a:

I don't have a Northstar but have flown one and watched dozens of flights. I'd say any design that's been around 25 years and has the following the Northstar has doesn't need to prove anything.

Sure, you can modify the design. Ireally like Yak Dude's canopy modification (the Coast Guard scheme two pages back). That's what bashing a model is all about. But your "improvements" may not appeal to the majority.

Yak Dude

Hey, I finally got a video of my Coast Guard Northstar. Several touch and goes with a very high AOA at the end for a landing. I call it the stop and plop. Last winter I flew at Bakersfield and did about 22 touch and goes in 10 min. Just wanted to see how many I could do. Anyway, I've had no bad habits with this plane. I've pulled off the water and instantly in a turn with a tight pattern to a landing.
Thanks for the comment on how I did the canopy. Here is the link to You tube. Wes.

http://www.youtube.com/watch?v=AezI3yF5UPQ

Cougar429

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Love the vid. Nice flying bird.

My Polaris floats were not toed in at all and I don't remember the instructions or plans showing any either.

Glad to see action on this thread again. Was starting to seem a bit stale for a while.

Quikturn

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Nice video Yad Dude! Like the paint scheme too.

A friend of mine gave me a finished Northstar a few years ago. It's built, covered with a fabric like material and primed. I recently noticed the engine pod is slightly angled to the left. I havent measured the angle yet but I think I may have to remove the pod and straighten it. For power, I have a Webra Speed 50 for it. It has great power and is light. I may even put a Macs muffler on it if I can save more weight. I figure the less weight in back, the less weight I'll need up front. I want to keep it as light as possible. Now I just need to settle on a good paint scheme. I really like the Coast Guard scheme (fitting too). I also like the Thunderbird scheme from the 60's with a silver body.

flybyjohn

My Feedback: (2)

The Polaris wing rocks pretty good but only in high alpha. On the straight and fast it will tail waddle (wag its tail back and forth) if there is any wind to speak of. I think this is coming from the crosswind wanting to blow the tail over and then it corrects and then gets blown again. As for the v bottom, I have flown float planes with V bottoms and flat bottoms and the flats always get off the water quicker, so if your having a problem getting up off the water then the V will probably just exaggerate it more.

Cougar429

My Feedback: (3)

The only difference I've found is flat bottoms require more finesse on touch down or you can almost guarantee a bounce or two.

LADDIE

I am delighted with amount of discussion around the NS.
I never installed V shape bottom. If I remember correctly Scott, producer of the Polaris Ultra ARF told me that he had first version produced with V shape hull. The plane was dog on the water.
I do not see any benefit in putting toe in on the tip floats. In a way, there is the toe in created by the shape of the bottom on the tip floats.
Again, I do not see any need for the step on the tip floats.
The height of the step on the hull is fine as long as the model’s weight is less then 8 Lbs. If heavier, then I would increase the depth of whole bottom up to the step by 1”. This will allow the model to sit at higher angle preventing the water from spilling over the leading edge, specially at the wing tips.
Important thing is location of the CG. The optimum place is on the step, with the fuel tank FULL.
The skipping when landing can be eliminated with practise. The NS can be slowed down so much that the model is hardly moving forward when touching the water surface.
In the video YAK in post 404 is showing us, clearly shows how smoothly stock NS can fly and land.
I love seeing experimentation. Someone might come up with perfect NS.
Laddie.

skywagn180

My thinking with the step on the tip floats is related to the manner in which a normal NS rotates in the videos I'm seeing. I'm leaning toward shaping them to a point as an alternative though. During rotation, I'm seeing a lot of spray off of the squared off and flat rear portion of the normal tip floats as the AOA is increased enough to fly out of ground effect. That indicates unnecessary drag and I feel a step or aft taper to a point could reduce the effect. Yes, it is just fine on a light plane, but as you know I'm trying to get a heavier one to handle better. This is the point where my NS starts slowing and prevents rotation on smooth water. Please don't freak out on me fans. I know your 6 lb. NSs are powering through all this just fine.

I doubt a properly constructed V hull would decrease water performance. That is like saying a jon boat or sled handles and accelerates better than a v bottom ski boat. If the V hull is not shaped correctly and did not allow the craft to rise out of the water with speed, drag would actually increase due to the greater surface area contacting the water. That could have happened, but I doubt it. Interesting. I just haven't seen a flat bottom flying boat or float plane built after the 30s. I understand the NS is a model and a very unique one at that. Just because I want a V hull doesn't make me a criminal or anti-NS.

I see your point on the toe in. Looking at my tip floats I can see the shape you referred to in mine. The shape on the botton of a V would probably amplify the effect though. My idea is that with an aggressive V shaped tip float, drag will decrease throughout the TO run as the tips rise while still providing enough bouancy at rest. Also, the V with slight toe in should tend to raise the low wing and provide stability and better directional control on the takeoff. As far as landing, my NS lands very well, but any extra speed causes a bounce. Any slow landing slaps the water kind of hard. A V hull would allow for a soft landing in a wider touchdown range in theory.

I don't appreciate the lack of support from some of the fans in this forum. I do appreciate feedback such as this. If you don't agree with me tell me why. Please don't tell me how long the design has been around and it is perfect because a lot of people love it the way it is. This is probably one of the most modified RC planes ever designed, so give me a break for wanting to enjoy making mine my own. And please don't make the mistake in thinking I am not a loyal fan of the design. Thanks for the input.

skywagn180

What a great plane! What is your weight? That thing handles very well. I've yet to see a rotation that slow in any videos. What's your trick?

skywagn180

I get the tail waggle with the NS too. So apparently the wing rock is not as wing loading related as I thought. Thanks.

skywagn180

Oh... And how did you go about getting a 12x6 APC on there? I wish I had that option. I can only use a 10 inch prop. Don't tell my wife. Lol. I bet my .46 would turn enough RPMs in high speed flight to blow up with a 10 inch APC 2-blade. The three blade I run is killing me. Do those wing tips help with wing rock and/or tail waggle?

[email protected]

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get a balsa usa enforcer with a os 61 engine will do what evere you want it to do>> ive had 2 of them>> also had 2 with a byron fan unit and a os 91 fan engine os 91 fan engine both ways it will do what you want out of it

Quikturn

My Feedback: (12)

Skywgn180, I'm no hydro expert but I think a V hull will want to sit deeper in the water. V's probably provide a smoother ride and have better directional control but you want a nice flying airplane not a boat, right? Most if not all seaplanes tend to be high wing designs. If you really want a V hull, I would add it to the bottom of the original airframe so it can sit higher off the water rather than modify the original hull. The flat bottom John boats get more hull out of the water at speed which is what you want in an airplane so it can break free and lift off.

I agree with no toe in on tip floats as this would add drag.

LADDIE

Here is my electric NS with 11” prop.
The wing tip floats were tapered for looks.
I am enclosing some pictures of my electric NS. Notice amount of space between the trailing edge and the water. Notice amount of angle of attack when resting. Notice amount of spray on take off.
One photo is showing the version with long nose. Idea was to move servos and the receiver battery forward so no lead was needed to balance the model. The model was 16 oz lighter, but I did not liked way it was flying. One major fault was when landing. I could not land the model like original NS. When attempts were made to land at angle as with the original NS, unexpectedly the nose would shoot up and model would stall and fall down tail first.
My guess is that at higher angle of attack the centre pressure was traveling too far forward maybe even in front of CG causing pitch up.
If I was to build new NS with the long nose, I would eliminate the leading edge extensions to reduce the wing area in front of ihe CG.
Laddie.

[email protected]

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very nice northstar can you tell me how to post pictures on this site thanks allen

Cougar429

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skywagn180, can't tell you which pages, but if you start from the beginning of this thread there are quite a few suggestions, including what was required to fit the larger props. The quick and dirty is possible later by a bit of hacking, (ie, cutting off the pod and building up the stab) but it's best accomplished during the build. In that you can also shorten the tail and move the motor forwards. These mods solve two problems, but unfortunately also seem to amplify power pitch changes.

I had also posted about my reverse cut floats, something you saw later on the Polaris and Ultra. With mine the intention was to reduce drag and also alleviate some of the wing rock tendency. Since I upped power to the OS55 I don't really notice any drag reduction in flying, but it definitely cuts suction at the start of water accel. Here's a pic of mine again. That bit of black is a rubber cap on the end of the plastic antenna guide tube running from the front compartment along the leading edge of the wing.

skywagn180

I own three boats. One is a jon and two are v hull. Trust me, a flat bottom has waaaaay more drag. The only reasons boats have flat bottoms is for resting stability and clearance in extremely shallow water. I'm confident in the acuracy of those statements. V hull boats, planes and floats are nearly completely out of the water on plane reducing drag significantly. I'm surprised people are arguing against this concept. You are very correct about the depth issue. I get the agument that a light NS doesn't really need a v, but I think it is a very strong possiblity it could improve takeoff, longitudinal plane stability and landing. If I do add a v, it will begin at the stock side edges and extend further down into the water. This will also increase step height allowing for a higher AOA during rotation. A v hull would be a very easy mod.

V shaped tip floats with toe in would create very little drag in theory. As the float gets on step, the exposed surface is very minimal and so would be the effects of drag. I could see if the design of the v shaped tip floats had them running fully in the water on plane that could be an issue. My thought is to position and design them so that on plane only the very back tip would run in the water. If the wing dropped, more area would be exposed to the water and the very mild toe in and natural angle on the v would force the wing back up and also counter the increased drag on that side with a force toward the faster wing. The two tip floats would work together to create a positive static and posive dynamic stability in all three axis as the plane accelerates. This is all theory and demands some testing though. Thanks for the input, hopefully you kind of get what I'm thinking about doing. I know it's complicated.

skywagn180

Thanks,
I'm starting to get motivated to rip the covering off my NS and get crazy with a rebuild. I have a lot of ideas now and want to try some things that will require starting over. I would love to get my .65 AX on there somehow. I would definitely have to rebuild the tail and may do so. Of course the pitch and power thing is an issue, but my radio can take care of all of that. Thanks..

skywagn180

Very nice Northstars. The pitching up is interesting. Thanks for the info. This all helps.

Cougar429

My Feedback: (3)

That problem of uncontrolled pitch is what I believe is called "Control Reversal". Been out of the classroom far to long to remember the proper terms, but I think the longer nose places more surface area ahead of the center of the pitch axis. With high AoA you will get that surface area forcing the nose even higher, overcoming any compensation from the horizontal stab or control from the elevator. You can see the same effect when installing floats on a conventional aircraft layout and is the reason supplemental yaw control is required, (the extra vertical surfaces added to the tail). With the NS the same problem would occur if we extended the strakes too far forward or made them too large.

skywagn180, there are a few tricks you may try before going full hog on a rebuild to help get it to launch. Along with the formentioned aerators we tried years ago perhaps simple spray rails formed from light ply or plastic sheet to conform to the bottom/fuse intersections from about 1/3 back from the nose to the step may help break suction and add some hydrodynamic lift at speed. Try them angled out 45 degrees from vertical. This would be akin to what is designed into boat hulls for lift and stability, (I basically grew up on the water and had lots of experience with many different hull designs. My father and I were interested very early on in the Sea Knife concept).

An even easier attempt could be to bond and trim foam sheet to the front bottom, tapering it from the surface of the existing bottom to thicker at the back to deepen the step. This would add bouyancy to the fuse, (to lift the floats higher as well) and increase your static AoA. Again, the key would be to keep the intersection between the bottom and sides as sharp as possible.

skywagn180

For those of you that might be interested in the official weight of my painted Northstar that has had trouble taking off from smooth water, I found an accurate scale to weigh it today. I haven't had time to work on mods yet though. Dry weight is 8 lbs. 1 ounce. That includes 15 ounces of ballast in the nose cone. The previous plane this .46 fx was on was a 6lb. 12 oz. Extra 300. It seemed like it would go to the moon on this motor. So it isn't as heavy as I thought, but still a little fat. When I get time to work on it I'll report back with the results.

skywagn180

Here is my NS.

Aussieflier

Hi,I have been following this thread and thought I might bring something to the table.I think that it should be said that good design in modelling also includes the ease of which the model can be built. The designer of the Northstar has taken this into account and as such many modellers over the years have comfortably started, completed and have successfully flown their Northstars. For the more experienced modeller the Northstar's simplicity encourages one to make a few modifications if for no other reason than to build a little bit of ones self into the model. In my opinion I think it a little bold to suggest that Northstar is or was lacking in it's original design. If you were to approach any designer of full sized aircraft and tell him that you intend to build his design 40 to 50% heavier the his specification he would tell you in no uncertain terms that it will not fly. It also needs to be said that since the Sea Dart ,no aircraft company ( that I am aware of )has even tried to get this formulae for an aircraft to work, I think this clearly indicates that some very expert designers have decided that a delta wing flying boat is not an easy task. The Sea Dart design required water skies to get enough airspeed and AOT to lift off, this was all about weight.A few months ago some friends of mine encouraged me to build a Northstar, my background is F3A and so I decided to upgrade the look of the model a little. I would not dare to say that I have improved the model, perhaps I can say that I have prettied it up a little. I have built the model with an electric power plant as was suggested by my friends, this turned out to be the heavy option but I think the power to weight is OK, as I have a great deal more power than a 0.46.The motor is Turnigy 600 1100 1.1KV 50mm, I am running 6S and turning an APC 10 x 7 at 19,000 rpm while drawing 105 amps.The fuselage sides and lower fin are boxed up as per the original plan, the turtle deck, canopy and nose upper are all planked in 1/8 balsa, as is the engine pod. I incorporated the 1/8 balsa fuselage bottom and then fitted a 1/8 ply keel, I then planked the Vee bottom with 1/8 balsa to form a very strong triangular box hull. i.e. All of the Vee hull is extra depth to the model. I also added hardwood strakes to give the hull more lift out of the water as well as better shock absorbing on landing. The canopy is 45mm taller than the original lines of the fuselage. I have more than doubled the height of the step in the bottom of the fuselage, I also lengthened and tapered the wing floats.The Elevator servo is in the engine pod.The fuselage, fin and engine pod are all finished in 1/2oz glass and epoxy, the bottom of the fuselage and floats have the recommended 2 layers of 2oz glass and epoxy. The wings and tail plane are covered in Solartex.The entire model is painted in Createx Auto Air and covered with 2 coats of 2 pack acrylic clear.The entire airframe (including all control surfaces) prior to glassing, covering and painting weighed 1.5 kilos this includes also the elevator servo and 150 grams of cable running from the battery compartment to the motor.After glassing, covering and painting the airframe weighed 1.9 kilos. So all of the finishing including covering and glassing the bottom added 400 grams total. I think I could get that down to less than 300 grams if I did it again.The total weight of the finished model including the 800 gram battery is 8Lb exactly. So it is comparable to a 7 1/2Lb glow model with a full tank of fuel. There is no lead in the nose.A good 0.46 develops about 850 watts at the shaft. This electric setup given an efficiency of only 85% should develop about 2000 watts at the shaft. In the end I think I am about a pound over the ideal weight but with more than double the power.I have yet to fly the model but I should have the opportunity to fly it in a few weeks.CheersLionel