Seaplanes Aircraft that typically take off and land on water...radio control seaplane discussions are in here.

Arrow and Northstar (Again!)

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Old 07-20-2016, 07:35 AM
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bigR
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Default Arrow and Northstar (Again!)

Hi all,

I know these planes have been discussed many times on this forum but I have a question. I have the opportunity to obtain a partially completed or crashed (I don’t remember which) Northstar and wonder how to proceed.

The Arrow seems to be a simplified Northstar but without the tail. What difference does the absence of a tail make? I would think that the Northstar would have more control with the extra flying surface. There are many copies of this basic design (Polaris, etc.) with the elevator/horizontal stab. Is there a good reason for this added surface?

From what I have been reading, the Northstar needs a lot of speed to take off relative to other planes of the same wing loading. The wing cannot rotate to a high angle of attack. At higher speed the vehicle planes on the step and tip floats and sort of takes off in a sort of flat attitude. Is this right? Does the added lets call it, moment arm, of the horizontal elevator aft of the wing help with rotation? The Arrow elevons would seem to be less effective at low speeds. Any experienced flyers here to explain the takeoff characteristics of both planes?

Reason I'm asking is that I want to build one or the other and use a heavy four-stroke motor. Yes, I have many two stroke and electric power plants but don't want to use them. The Arrow doesn’t have the horizontal tail. The amount of needed nose weight could be reduced without having to compensate for the elevator/stab mass and associated controls.

Would it be a good idea to make the pylon/fin with provisions for a removable tail? That way one could do a comparison of the “pure” delta wing and the delta with a tail planforms.

Some food for thought.

Thanks,

John in Kalifornia
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Old 07-20-2016, 09:04 AM
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jeffo
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I've had both Arrow and the Northstar,both are great fliers,it all depends what you want.The easier to fly is the Northstar.The faster is the Arrow.If you use a four stroke,make sure you have prop clearance,you may have to raise engine box,you should use a perry pump,with the gas tank on the C.G.. If you do build the Arrow,put small wing tip floats,it will make it a lot easier to take off water.I fly mine right off the grass,no wheels.Once you get used to the Northstar,you'll want the Arrow.I have a thundertiger .45 on mine,and it's wicked.My buddies who have Northstars wish they built the Arrow.Two things on setting up the Arrow,3/16 reflex on the elevons,and use 2-56 steel rods to evelons.Once you find its sweet spot,hang on.
On the Nothstar you definetly have to make it more rigid as the plastic nyrod extends from the engine box to the elev. control horn. jeffo
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Old 11-17-2016, 02:06 AM
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Strykaas
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Thank you Jeffo for sharing your experience.
I am also preparing to build an Arrow.
Did you build it exactly as per the official plans ?
Some here modified the pylon centerline to increase downthrust. Is it something you have also modified or is yours perfectly stock ?
Thanks !
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Old 12-27-2016, 09:06 AM
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Having had Northstars and having flown a couple of Arrows all I can say is most of the Arrows have ended up in the dumpster and we still have Northstars that are 10 - 15 years old. My advice; forget the fourstroke and put in a honking 46 - 55 and live with it. These are both fast airplanes and don't take to put-
putting around the sky. If you want four stroke power look towards a laker or a more conventional layout.
Can't say I agree with tip floats on the Arrow; they are very sensitive on the water and any tip drag will induce a spin out. Both planes need to get up to speed and on the step and then allowed to fly off. Once in the air the worlds your oyster.
Peter
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