northstar help
 

Hi all, I gust completed my first northstar and am having trouble getting it to break free from the surface of the water. I followed the building instructions as close as any serious model builder could have. I did do some mods as far as the fuel tank being relocated to the c of g allowing servos to be installed in the nacelle for the throttle and elevator. I planed to use a os 46 that I have but cant get the darn thing running proper, so I installed a os 40 la gust to see if this is worth buying a new engine. I'm guessing the weight to be about 7-8 lbs, is this engine to small? Is there any thrust angle that may cause problem with breaking free from the water? any help would be greatly appreciated. Thanks, Bart (man)

RE: northstar help
 

Try reflexing the ailerons down a bit. This should help to get the wing out of the water then build up speed before easing in elevator. The 40LA wouldn't be my choice. It's not enough power. Not for me anyway although I can get the plane airborne with my Webra 50 well throttled back to about what I guess would be a similar or less power level. If you knew the plane well you might get it into the air (I think LA used to stand for Lame A**) with a struggle if you are not cruising around with a death grip on the up stick. ;)

Put a strong 46 in. It will fly. Thousands do. It's fun. :)

RE: northstar help
 

I don't think I'd drop the ailerons, they are too far back on a Northstar and may cause more trouble than help.

But there is no doubt in my mind that the 40LA has to go.

Get a good Ball Bearing 46 - Even a cheap one like the TT or Evolution. They are great engines for around 80 bucks.

RE: northstar help
 

I've been flying them drooped for a dozen years Mike. No trouble at all. Can't tell you how much. I have a hard enough time remembering what I did yesterday let alone that long ago.

RE: northstar help
 

The plane should get off the water with a 40 LA. If not --- is the engine propped correclty? What rpm with what prop? Is the plane balanced according to the plans - 16" ahead of the TE of the wing - not of the ailerons? If you moved the tank forward, why in the world did you put the additional weight of servos back in the rear? That defeated the entire purpose of moving the tank forward. In addition to not knowing what your balance point is (CG) I would think that putting a 40LA and its tank that far apart - and therefore the tank well below the engine (much less the carb) - has got to have a significant negative effect on the engine operatiopn.

RE: northstar help
 

Then I take back what I said - It's not the first time I've been wrong (And sure as hell won't be the last! )

But I still think it needs, or at least deserves a bigger engine.

RE: northstar help
 

No doubt a better engijne will give improved performance - I normally use either OS 46FX or ST51 on mine - but a 40LA will get it up and flying if it's built correctly. My most recent one came in at 6# 9.6 oz., so if his is close to the 8# mentioned he may well need a different engine. I'd also be concerned about the CG - there may be too much nose weight keeping it from rotating. Also, some folks smooth out (round off) the step, when it needs to be a sharp edge. A rounded step causes significantly higher drag.

RE: northstar help
 

The 40LA would be fine..............as long as you had two of them. :):)

RE: northstar help
 

I'll clear a few things up, The plane is balanced at 16 inches from the trailing edge of the wing not including the ailerons. I moved the fuel tank to the c of g and installed a mini servo for the throttle and a standard servo for the elevator so I could make the elevator link as strong as a 4 inch piece of piano wire. Try getting any deflection out of that! I also installed a perry pump directly behind the carb, so fuel is no problem. I have a 10-7 prop on a 3 year old la that came from the avistar I learned to fly with. Ok the method to my madness is to move the fuel tank to the c of g and place the servos in the nacelle for the stronger elevator link and the comfort that as fuel burns off my plane wont change it's balance. All I basically did is move the weight around a bit to make make (in my mind) a more user friendly air craft. I'm not looking for a speed demon, I'd get another shrike for that. I think I'll be buying me a new engine. I thought I would let you know that I have a set of kyosho ducted fans from a lear jet kit and am going to scratch build an electric version af the arrow (corporate style). I might be looking for some speed out of that. Thanks for all input. Bart (man)

RE: northstar help
 

While I understand the reasons for the fuel tank and servo placements, the following is for anyone else who is reading this thread that's in the process of building a Northstar...

The movement of the tank is, in my opinion, not needed. With the tank in the nacelle I have never had a problem with trim change during a flight, and the addition of a pump adds some degree of complexity and another place for a fuel system problem.

The placement of the elevator servo in the nacelle is also - again in my opinion and after having built four Northstars - not needed. First of all, proper support of Sullivan Gold-N-Rods keeps the elevator control surfaces completely tight and with absolutely no slop. See pictures for a way to ensure this as well as a similar way to eliminate rudder sloppiness. As with the movement of the engine and addition of the pump, the running of long servo leads from the front (nose) of the plane to the nacelle adds a level of uncertainty due to the length of the wiring, connectors, etc. In addition, whereas the radio compartment of the plane – the cockpit area – is pretty much water tight on my planes, the nacelle area isn’t and when/if the plane is dunked the servo in the rear will get soaked.

But, if it works for you, fine. As I mentioned in my earlier post, if your plane is at or above 7# it’s heavier than it needs to be. Hope you get it off the water.

RE: northstar help
 

Not wishing to hijack this thread, but I just bought a Northstar kit myself, having seen one flown a few years ago at the Island Lake Park event here in Michigan. (Second-hand, and missing the building instruction set, but that won't stop me.)

I am curious to know if anyone has successfully electrified one of these. Given the current state of the art I'd reckon it to be just possible. Rule of thumb says 600 watts at 80% efficiency ought to do it, but any other experience would be useful.

I'm especially concerned with determining what prop-speed it needs. If I could know what RPM a nitro-burner produces on what prop to sucessfully fly the beast, it would help a lot.

RE: northstar help
 

I fly with 10 x 6 rpms are around 15,000 with an ultra-thrust muffler :D

RE: northstar help
 

The Island Lake Float Fly is a good one for getting information regarding the Northstar. See the picture from RCM a few years ago ( I built the second and third ones from the right) as an example of what is there most years and you'll notice that Laddie - the designer of the Northstar - is normally there. Since the float fly is this coming weekend, http://www.skymasters.org/events/mid...nal/index.html why not drop by (since it's so close to you) and ask around for the info you want? I'll bet that by now some of the Northstars there will have been electrified - maybe even one by Laddie since he does a bunch of electric plane building and flyng.

RE: northstar help
 

[:o]Sorry to say that I've missed it. Not because I didn't check the thread, but rather because my creaky old repiratory system was introduced on Thursday to a rinovirus it hadn't met, and they just HAD to get aquainted. Consequently I've been nearly comatose on cold medication for the last 72 hours. All the more frustrating because ILSP is less than a mile from my office.

Obviously that's static RPM at full throttle, and that gives me an idea of the HP required. I get the idea that 10" is about all the prop diameter you can swing without raising the thrust line?

RE: northstar help
 

In a (successful) attempt to allow the use of a larger diameter prop on one of my Northstars, I cut out a 'divot' in the fuselage section right where the prop would strike it. Works fine.

RE: northstar help
 

Hi all, It's been a while. (all winter and then some). Any how, I replaced that old 40la with a 46 ax and what a difference! I went to the lake on memorial day and by the timeI got the plane and all my flying gear out of my truck, There must have been 50 spectators gathering to see what I was up too. This being my second try to get this thing off the water, I taxied into the wind for about 50 feet and roled up the throtle. The plane was on step in gust a few seconds. I put some up elevator in and the plane lifted off the water at about a 30 digree angle of attack and was climbing fast. I figur I had about 25 to 30 feet when I started to center the elevator stick and the instant I let off the stick the plane porpoused comming down and smacking the water about as hard as any belly smacker I have ever seen. To my supprise The plane appered to be intact and floating well about 100 yards off shore. After all of the spectators were done going (OOOoooo) I noticed the engine was still runing, so I thought what the heck and roled up the throtle again. She got write up on step and a little up elevator we were climbing off the water again at about the same angle os before. I let it climbe to about 100 feet this time and as soon as I let off on the stick it was on it's way back down. I regained control and after putting all up trim my tx could give I could fly with what I call a heavy thumb. I did a few basic roll's and loop's for the crowd and a few approach runs in all about 10 minnuts of flight I settled her down on the water and taxied upto about 20 feet from shore when the engine stalled. (still resulting in to a giant HOORAAA. one of the kids swimming went out an brought it back for me). The reason for the stall was empty fuel tank sindrom. I'll be doing a center of neutral test and split the differance for the next flight. Any ways, I'm verry pleased with the way she fly's.

RE: northstar help
 

She sounds a little nose heavy,mine flew nose heavy too. I ended taken out 4 oz. out of nose and now she flies great.
If your elev.has a lot of up trim take an oz. at a time out and fly it.What I do is get to safe altidude and stall it. throttle back and pull back on the stick gently with nose up attitude. AS long as when you come to complete stall,the nose drops foward you have a stable plane.do this until your elev. is level with stab.
Note;If she starts getting real squirrelly stop and maybe add an oz.-Good luck-Jeffo

RE: northstar help
 

I did a center of neutral check by hanging the plane level from a string attached from nose to tale,and the result is 14 inches from the trailing edge of the wing. Thats a 2 inch difference. I'm going to rebalance at 15 inches and see what I get in lead reduction from the nose. If it only a few oz I'll go with it as it felt realy nose heavy. I would like to thank every body that gave input as knowledge is power. Once again THANK YOU!!! Bart (man)

RE: northstar help
 

When you fly hands off do you have to fly it with the elev. in an upward postion?If so it is nose heavy.It makes a stable plane,but you could have trouble taking offand if you have to deadstick you will have a heck of a time trying to get the nose up.-Jeffo

RE: northstar help
 

With the CG 2" rear of what it is supposed to be (16" from TE), the plane is tail heavy (not enough weight in the nose), not heavy in the nose as you imply from the above. You will need to add weight, not remove weight, in the nose to get the balance right. Strongly suggest that you balance it as Laddie recommends, and simply marking the 16" under the wing (I always use small strips of Monokote to mark my CG locations) and then placing your fingers at those spots will easily tell you if the balance is correct. Not sure that the method you mention is accurate with the design of this plane.

RE: northstar help
 

Newc, Hows it going? Apperantly you got side steped someware in this topic. The plane is balanced at 16 inches as stated in the plans however, with the mod's I made such as relocating the fuel tank and moveing the throtle and elevator servo's to the engine pod the CofG has shifted back towards the tale. The equipment in the pod are lighter than the fuel tank, and the 16 inch location also acount's the weight of the fuel. Hope this makes sence to you. Thank's Bart (man)

RE: northstar help
 

Moving components has nothing to do with where the CG is supposed to be, only where it is. In other words, no matter what components you have in any locations, the CG should still be 16" in front of the TE.

Also, CG should be at 16" (as above) when the fuel tank is empty, not full. In the design of the plane and the establishment of the proper CG Laddie made the recommendations as stated and they have worked well - with none of the issues you have stated - when the CG is as stated on the 4 Northstars I have built and flown.

Add some weight - even temporarily - to the nose to get the CG where Laddie established it and fly it. I bet you find your issues are gone and the plane flies well.

Good luck.

RE: northstar help
 

Newc, I sugest you check out a poast that was poasted on 4-21-07 in another northstar topic and you might want to take back that bet. As stated before. with the mod's I have, the northstar balance point shifts back to app a half inch infront of the step.

RE: northstar help
 

Putting the tank just ahead of the C/G is what my Northstar has. You hit it right on the head when you mentioned that you can take almost a pound off the weight. I have gone so far as to have mine balance right on the step and it flies great. It cures one of the criticisms of the North Star having a soft elevator. I used the Perry diaphram pump mounted just behind the firewall and ran 1/8" hard nylon tubing for a fuel line from the tank compartment to the pump. Just hold your finger over the venturi when starting and release it when you see fuel starting to come. Runs are very reliable, good idle and top end. A Supertiger 51 motivates mine.
Peter I hope this gives you some ideas Newc. Thanks, Bart (man)

RE: northstar help
 

I'm truely amazed how you guys can build the Northstar at 6 1/2 lbs. I'm not a Northstar expert but I'm on my 2nd season with one and having a great time with it but mine weighs 8 1/2 lbs dry. The only additional weight I can think of was the 1/16" plywood on the bottom after I tore open the bottom on a hard landing. Surley that doesn't weigh 2 lbs. I too put my tank on the C/G with a mini servo in the tail for the throttle. All other servo's are as far forward as possible. I had to add 1 1/2 lbs of weight in the carved out nose to get it to balance on the correct C/G. Mine is powered with an OS SX 50 swinging a 11/8 prop.

As for flying it requires a long take off run, but once airborn its pretty fast and pretty much a handfull to fly : ie very touchy on the roll axis. My greatest joy is touch and go's on water thats glass smooth. Its an easy plane to land and when you greese them in, its a real crowd pleaser.

K.O.