Aussieflier

I mean to say wing rocking.

skywagn180

The takeoff run varied as I changed the tab angles. The shortest was about 200 feet in a light 2-3 knot direct crossword. I have a feeling that a different prop will improve that further. It's a high pitch three blade and low speed thrust is not its strong point. I am definitely changing the airflow off the tip floats and that might have something to do with the wing rock improvement. At first I tried to convince myself I was being optimistic, but others that saw it fly before were noticing the improved stability in high load turns and loops.

Cougar429

My Feedback: (3)

I'll second both the congrats on your successful water ops and that the squared off floats are the prime suspect for the wing rock. Have no real comparison since it has been a long time since I flew even a moderately stock NS, but you should encounter wing rock even on one with the tips modified when you increase AoA.

This seems to be normal with wings of high leading edge sweep angle. If memory serves it's the reason the Avro Arrow and F-4 Phantom have "Dog-Tooth" leading edges and the Falcon 20 works with fences, (although from what I read Marcell Dassault always felt and resisted add ons as they meant the original design was faulty). Both are methods to deal with spanwise flow and separation. Now that I think of it, fences can be added to the Polaris Ultra very easily. Will test them out and if they are a benefit will perhaps incorporate the idea in a future NS build.

One thing I found with the NS I built was it was always difficult to be consistent with the long leading edge profiles, some turning out sharper or blunter than prior sets. I believe that will have a large effect on how the wing performs at different speed regimes.

skywagn180

My next stunt will be removing some nose weight. The CG is now located an inch or so forward of the step without fuel. I added weight slowly until I found it comfortable and reasonably stable to fly. The primary reason I had to continue adding weight was to tame the violent wing rocking which worsened the further aft I was in CG. Now that the wing rock is better I may try to get away with a few less ounces of led and see what happens. I want to stress that I am not recommending any of the mods I am working on. There is clearly no substitute for building a much lighter airframe than mine. I am throwing a band aid fix at a plane that is outside of its design weight limits. I really love flying the NS and might just build an ultra light custom version when I get some time.

skywagn180

My next stunt will be removing some nose weight. The CG is now located an inch or so forward of the step without fuel. I added weight slowly until I found it comfortable and reasonably stable to fly. The primary reason I had to continue adding weight was to tame the violent wing rocking which worsened the further aft I was in CG. Now that the wing rock is better I may try to get away with a few less ounces of led and see what happens. I want to stress that I am not recommending any of the mods I am working on. There is clearly no substitute for building a much lighter airframe than mine. I am throwing a band aid fix at a plane that is outside of its design weight limits. I really love flying the NS and might just build an ultra light custom version when I get some time.

[email protected]

My Feedback: (1)

a balsa enforcer is a much better p[lane ive had 3 now and sold them all had os 91 engines number one flyers

SBOT

I am building a Northstar; I'm thinking of leaving the ailerons full width instead of tapering them as shown on the plans. Are they tapered for any particular reason. I can't think of any reason why they should be tapered. Anyone have any thoughts.
Thanks,
Oscar
I had posted this Question in Seaplanes as a new post, but after a full day did not get 1 view; so I will try posting here.

LADDIE

When I was designing NS, I drew the tapered ailerons for two reasons. I like the look of tapered ailerons and I was concerned that without the taper, the ailerons might be too sensitive. If you want, build them with no taper. You can always cut the taper to them later on.

Laddie.

Cougar429

My Feedback: (3)

Surprising there has been no action here lately. Mind you, this winter has been absolutely horrid, with cold temps and winds making any attempts at this "Hobby" a bit of a stretch.

sbot, any progress on yours? You will find tapered ailerons are more than effective. The floats prevent leakage at the ends when deflected downward, so much so that to get a relatively axial roll I built in differential.

SBOT

I was covering, almost done, when a move into a new house has had me sidetracked for weeks. Had to build a new shop. Then the shop got filled with stuff; so now I have to build a storage building because I can't get into my shop. Then I had to build a front porch. Next is grass and flower beds, landscaping. The only free time I have is at work; thank god my job gives me alot of free time. Right now I'm building an RC Rascal with a new NV .061 I got for Christmas. Glad I have a job so I can pay for all of this.

Aussieflier

Hi Guys,

Somebody sent me an e-mail asking about my Northstar and I managed to delete the e-mail before replying, Sorry. Hopefully you will see my reply here.

My finished weight ready to take off with a 6S 5300mha battery is exactly eight pounds without the wheels fitted, I have never weighed it with the wheels on.

The motor is 1100 Kv, and draws 105 Amps while turning an APC 10 x 5 Glow Prop at 23,000 RPM. Yes that's not a typo.

All of the information regarding the motor and speed controller can be found on my original post. The speedy which is good for 120 Amps continuous and 150 Amp burst has a build in fan and does not get hot even though the model is fully sealed.

The balance is at 1.5 inches in front of the step and the model has ZERO wing rock. I had a theory that an anhedral tail plane and a fully profiled fin may help the wing rock problem as these modifications work to make the tail act as if it were longer that it really is. I also tapered off the back of the floats for reduced drag and there was a theory going around that this may also have make an improvement with wing rock. Whatever argument people may put forward against the theory, the fact is that I have ZERO wing rock at any speed. The front of my model is much cleaner that the original design which would provide less turbulent flow of air to the wing when pulling a high G turn, perhaps this also helps. I have made too many modifications to really nail the cause of the wing rock fix.

Despite the models 8 pounds, it will take off the tarmac in a little less than 25 metres and climb vertically for 1000 feet no problem at all.

I have yet to fly off the water. I made a fatal error when programming the speed controller and set the low voltage power down to instant. The result was that I had an outfield landing into some scrub. Fortunately the model suffered only a cracked fin and I have about 4 inches of leading edge smashed back to the spars.

I have been slack in repairing the model but this has reignited my interest and I will get it fixed and onto the water very soon.

I only get about 5 minutes of flight time at full power, but full power is equivalent to a very very good 60 with a pipe. At half throttle the model is still going like a bullet and flight times of 7 to 8 minutes are quite achievable.

Cheers

Lionel

Goldenduff

Thanks Lionel, it was myself (and possibly others?!) that requested the information. Glad to hear she flies well.

What do you folks think of this petrol engine for the NS? http://www.nvengines.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=159&category_id=1&option=com_virtuemart&Itemid=65

306g without muffler and apperntly performs like a .40-.50 and the prop clearance fits.

I have had a NS kit sitting for years! Got it when I got married, 2nd kid on the way and am working on building a shed next to my new house so it might get started this year!!
Will definately make one brushless but am going to duplicate all parts so I can make another one.....

Cheers, Adam

LADDIE

Hi Adam. That is interesting engine. From the engine specifications, it should work on the NS. Just try to keep the area behind the C/G as light as possible, so the least amount of lead will be needed in the nose to balance the NS.

Cougar429

My Feedback: (3)

Adam, since I have no idea of your experience or history, don't feel the following is condescending in any way. This is just my own take on things and advice I find goes a long way to every level.

They are a bit long in the tooth, but if you can find a RINGED version of the OS 40-45FSR you'd have a bulletproof powerhouse that would outperform anything else in this class. I've run many 2-strokes in the 40-60 range and in some cases it would also do that on half the fuel consumption.

The ringed SF was nearly as good. Has been quite a while and I cannot remember if that one had the 2-piece case, but splitting the housing made bearing changes far easier. I believe this allowed them to port the engine more efficiently. As well, building in the extra bosses to allow for that option made the case far stronger.

At one point I had 4 of the 40 FSR's, including tuned-pipe apps and even after 20+ years of storage they were honkers. In fact, even though I am nearly all converted to 4-strokes, I refuse to lose the last examples of a few gems, (Fox being the other maker hidden below the radar).

You can still find bearings and rings, (Bowman Rings) and since the rest of the motor is nearly indestructible can give years more service. My only advice on modding pretty much any 2-stroke was to add a remote needle setup which usually only ran in the $10-15 range. I see that one at least is similar to the OS55AX in that they slant the needle away from the prop. Good idea.

I had a look at the specs and unfortunately they don't list the sleeve type. This can go a long way towards durability as far too many motors, (from even top names in the business) suffered peeling or relatively fast wear. One other thing to watch for is when they list the HP output, but not the fuel used to get that rating. If you need to run 30% nitro to match their numbers then things are RADICALLY different. I'm of the opinion if you require anything over 10% to get the power needed for you craft then you have mismatched the two, (engine size too small).

p.s. Regardless of the option you finally choose, proper break in is key to performance and life in any engine. For some, Fox being the most extreme example I worked with due to the very hard cylinders, that break in was considerably more time consuming than most.

andypilgrim

I was asked to join this forum by one of your members. I have been building northstars for years and have built about 15 of them. I have been trying out different scales of the northstar. In the picture is a 3/4 scale with a evolution 40 on it. I have a few spare 3/4 kits cut out also if anyone is interested. Anyways just thought it would be nice to chat with fellow northstar fans.

Cougar429

My Feedback: (3)

Welcome Andy and good to see you here. Sent a PM regarding the 3/4 version.

Strykaas

Nice Andy ! So many Northstars and only one single pic ?

andypilgrim

andypilgrim

here is a really nice 1.25% turbine northstar, len bosvert from alberta built probably the coolest northstar ever!!!

Bob93447

I'm at the stage in the building of my Balsa USA Northstar kit that I need to make a decision regarding the canopy. Given the size of the working space, I'm thinking that a simple hatch, rather than a canopy, might be a lot easier to fabricate and just as useful. Is there any reason not to build the Northstar with just a hatch and not a canopy?

balsatermite

I built a Force 1 . years ago. It had a hatch and I never had a problem. I loved flying it.

Cougar429

My Feedback: (3)

Thinking back I estimate the canopy one of the most difficult parts of the build. Compound curves were a pain to fabricate with enough rigidity to retain the shape when removed.

A hatch would likely be a LOT easier, but may be more difficult to access if you have large hands like me.

Lamoilleriver

If I were to build another Northstar, it would be built using a hatch. Remember having a "bear" of a time building the hatch to have it come out half decent. Also would be prone to less chance of water leaking when flown from water.

LADDIE

The hatch is fine. Only reason I designed the NS with the cockpit was for looks. Good luck.
Laddie.

Lamoilleriver

When covering the Northstar, trim around the hatch and sides to make it look like a cockpit, because it does look cool with a cockpit.