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Dec 13, 2010, 01:53 AM
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Northstar Pusher?


Has anyone tried a pusher arrangement on the Northstar? It seems like it would allow a much larger prop for an electric version.
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Dec 13, 2010, 07:15 AM
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Not that I'm aware of and I don't see why anyone would. Biggest issue with the North Star is the weight in the tail, and moving a motor farther back, with the prop and attendant weight farther back than that, would only exacerbate the problem. Not saying it couldn't be done but see no realy advantage. To get a bigger prop can raise the pylon or if you plan ahead for it, install a groove for the prop arc in the fuselage. Could easily set up for a 13" prop if desired, and that should be big enough for any motor you might want...Pete M
Dec 13, 2010, 07:18 AM
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Maiden flight--unfortunately, not yet. Have not had a chance to take it to a large enough water area and I am hesitant to do it on land due to lack of wheels. I really wish I had installed a landing gear option, as I am concerned about belly flopping 5.5 lbs onto the ground. It seemed like a good idea at the time but now I am unsure. Too much trouble to retrofit gear as the wing was never prepped for it. Still, will eventually take it out, maybe when there is some snow on the ground. Thanks for interest...Pete M
Dec 14, 2010, 09:24 AM
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Try to fly it from the snow. You will like it. Good luck.
Laddie.
Jun 19, 2011, 08:19 PM
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Any flight data on your Northstar yet? It looks like a really nice setup.
Jun 20, 2011, 06:37 AM
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Shamefully, I have to say no. I STILL have not flown it yet, but it does look good in my shop. The plan is to get it in the air over the next week as I want to have it for my 4 Jul weekend in North Carolina. Will be sure to post results here once I have some...Pete M
Jun 21, 2011, 02:04 PM
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Pete,

I am about to tackle a Northstar Kit from the 80's. I have been trying to get the 6mm square carbon tubes from HK (but they are constantly out of stock) to use in place of the spruce spars. I do have a supply of the round carbon tubes; how did you put them in? With a long drill after wing assembly or with precut holes before assembly?


Bob
Jun 21, 2011, 02:59 PM
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I have a framed up Northstar that I still need to cover and configure for an electric motor. I didn't build it but got it framed up.
Jun 22, 2011, 06:12 AM
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Quote:
Originally Posted by bob93447
Pete,

I am about to tackle a Northstar Kit from the 80's. I have been trying to get the 6mm square carbon tubes from HK (but they are constantly out of stock) to use in place of the spruce spars. I do have a supply of the round carbon tubes; how did you put them in? With a long drill after wing assembly or with precut holes before assembly?


Bob
Bob, I predrilled them, just have to be careful to keep the ribs square. The design of the wing is such you just line up the ribs on a table, keeping the ends square (I used a right triangle against a vertical block that I had the ribs against), then pin them. Since I had foam ribs I used a piece of brass tubing with teeth filed in the end to "drill" the holes--if you plan on using the balsa ribs, use a drill press. Since I had the CF rods I didn't see a need to use the spruce spars so I replaced them with balsa, to save weight.

Hopefully will get mine in the air this weekend--it certainly has been a long time coming, as I have had it at the 99.9% point for a long time (just need to mount the cowl and balance it). Pete M

PS--I used white polyurethane glue to install the CF tubes, that stuff is great and it expands to fill in gaps. Way I did it was insert the tube, back it out 1/4", then put the glue on the CF rod and push it back into place, giving it a twist to evenly distribute the glue...
Last edited by pmisuinas; Jun 22, 2011 at 06:30 AM.
Jun 22, 2011, 10:20 AM
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Quote:
Originally Posted by bob93447
Pete,

I am about to tackle a Northstar Kit from the 80's. I have been trying to get the 6mm square carbon tubes from HK (but they are constantly out of stock) to use in place of the spruce spars. I do have a supply of the round carbon tubes; how did you put them in? With a long drill after wing assembly or with precut holes before assembly?


Bob
The greater the distance from the center of the wing ribs the spars are placed, the more efficient they become. Thin carbon strip bonded to the stock wood spar located at the outside edge of the ribs will be more efficient than round tubes in the center of the ribs.
Jun 22, 2011, 01:42 PM
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I would think that would be true only if there is an opposing spar...then I would agree. Otherwise, I am sure a round CF tube in the middle will be better than a single spar with a carbon strip on the outside of the ribs. The thickness of the strip is also going to come into play.

I am also pretty sure the single CF tube will be better than a pair of wooden spars--and a pair of CF tubes (as I put in this model) even better.

But to each their own...
Jun 22, 2011, 04:59 PM
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I had originally hoped to use 6x6mm square, hollow, carbon fiber pieces from Hobby City in place of the spruce spars. Unfortuneately they depleted their stock before I ordered and they have not had any available for months. It seems like my best option would be to laminate 6mmx1mm strips to the spruce spars and use those with possibly one carbon fiber round near the trailing edge. The goal is to maximize stiffness without adding too much weight.

I'm planning on flying this as an electric and I am looking for some ideas on minimizing the weight of the motor mount. It seems like there is a whole lot of weight and structure up on the tail that isn't necessary for an electric version. I'm looking for ideas on redesigning the motor mount to minimize it. The heaviest motor I will use is 330 gms but I am trying to keep it even lighter than that.

Bob
Jun 22, 2011, 09:34 PM
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Bob, look at Laddie's Arrow for a different way to do the motor pylon. I have one of those at the covering stage and I really liked the way the motor pylon was done--has a pillar stongly attached to a fuselage former that takes most of the stress. The pylon that is built around it does not have near the mass of the North Star pylon, in my opinion...Pete M
Jun 23, 2011, 07:17 AM
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Can you direct me to a post that shows the Arrow Pylon or do I need to buy a set of Arrow prints to figure it out?

Bob
Jun 23, 2011, 12:09 PM
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Quote:
Originally Posted by bob93447
Can you direct me to a post that shows the Arrow Pylon or do I need to buy a set of Arrow prints to figure it out?

Bob
Here's a link to a construction thread.

http://www.rcuniverse.com/forum/m_15..._1/key_/tm.htm

I'd often thought about addressing the cg issues of the Northstar by mounting the engine on a pylon forward of the stock position. I'd also use twin vertical stabs with a horizontal stab mounted high at the engine thrust line, to maintain some of the "thrust vectoring" ability of the original design.


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