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Northstar mods - Tell me what you think

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Old 02-18-2011, 04:17 PM
  #301
Cougar429
 
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Default RE: Northstar mods - Tell me what you think

Interested in the bracing from the wintg to the tail. I have a form of it on my Seamaster, (known for some problems when maneuvering) but have not seen it used on the Northstar before. Laddie has the tail area up to the tail/engine box glassed up for strength and I have not heard of anything extra required there. I've upped mine from the EVO 46 to an OS 55AX and there is some low RPM vibration from what I suspect is a natural airframe resonance, but throttling up dampens that out.

Since I wanted a bit less noticeable reinforcement, I sandwiched glass fiber between the ply bracing and outer skin and ended up with an extremely strong and clean structure.

I agree with the high vis scheme. That's why I did the Polaris, Seamaster and Northstar all up with the USCG pattern and it works well.

Lil' Hoss, you brought up one point that has me wanting to ask a question and hope for a bit of input. On my initial flight I found I too needed a bit more left aileron trim than I thought was necessary and suspect it could be due to the upper vertical stab installed perfectly straight. Some real aircraft actually have the stab installed slightly off to account for prop wash and wonder if that could be required here, as well. I'm hoping to pick up more C/F rod at the Toledo show and one option was to build a lighter removeable tail flight group. Could incorporate the offset at that time.
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Old 02-18-2011, 06:41 PM
  #302
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Default RE: Northstar mods - Tell me what you think

Hi Cougar
I don't think the vertical stab had anything to do with the trimming.. Just about every thing I ever flew need a bit of trim.
If you look close at my tail section. It is removable. This is to service the servo's if needed.
The reasons for the bracing is a friend of mine was taxing on the snow and hot dogging with the throttle and the mast let lose and damaged the wing. I was advised by him to support the vertical tower. What I did was a simple setup with little weight. (yet strong)

Hoss
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Old 02-18-2011, 08:25 PM
  #303
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Default RE: Northstar mods - Tell me what you think

Your removable tail looks identical to mine. I had to come up with it since there was no way to fit the plane intact in the car, (still looking for a Minivan). Even so, have to drop both back seats and it's a tight fit. Dut to that the Northstar usually goes to the field alone.
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Old 03-05-2011, 04:46 AM
  #304
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Default RE: Northstar mods - Tell me what you think

Need more snow.....
With only about a inch of snow on the ground the rudder doesn't sink deep enough into the snow.
Bring it in for a nice landing and than chase the plane half way across the field to get it.
I'm not complaining about "not enough snow" Just means that spring is on the horizon

Hoss
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Old 03-05-2011, 06:49 AM
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Default RE: Northstar mods - Tell me what you think

Know what that's like. I have an RC snowmobile on the way. What was I thinking?

Actually, brushless conversion................
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Old 03-05-2011, 11:23 AM
  #306
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Default RE: Northstar mods - Tell me what you think





Hello Northstar Lovers,

I am from Scotland and still getting all my ducks in a row regarding building the Northstar (I have a polaris). I have the plans and manual for the NS.
Balsa USA do the kit for the NS. A UK firm also do it from lazer cut plans. Due to currency conversion (benefit slightly reduced due to postage) the Balsa USA is about $100 cheaper. The UK firm offer lazer cut parts reportidly stronger due to constuction modifications (spar and rib joints etc) and light ply throughout. Their version has the wings sheeted in 2.5mm balsa whcih I like because it should reduce torsion and makes painting a custom finnish easier. The weight of each kit is supposed to be the same (hmmm, the guy from Balsa USA said not to sheet his version because it would be uneccessary heavy so I can only ASS U ME that the UK's kit is either heavy or offsets the sheeted wing with savings elsewhere.

Anyhow, I guess my questions are; is the Balsa USA kit strong? For an extra $100 bucks I could get light ply, supposed increasd strength from different joints/material and sheeted wings without weight penalty.

To summarise is the Balsa USA kit stong, (I know to build to fly not to crash but some wiggle room is always good!). The strengthening mods above (fibre glass motor mount) sound good. I was going to go with a seamaster strengtheing system with CF rods.

Any input appreciated. thanks, Adam

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Old 03-05-2011, 11:39 AM
  #307
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Default RE: Northstar mods - Tell me what you think

There are some weak spots that are dependant on the type of flying and environment. The sheeted balsa bottom was too thin and puncture prone for my intended snow work unless I glassed it, so I sheeted it with lite ply, (NOTE: since then water based laminating compound has made glassing fuses and structures much lighter than even thinned epoxy). Only error I found was the paint I used there does not seem to be fuel proof.

One other I found was the forward pylon. Instead of depending on the leading edge and outer skin I also added a lite ply brace running between the leading edge and main pylon support.

From some other failures of the wing at or near the fuse when working on rough water I added a spar brace. Would have been lighter stronger to use a C/F tube, but the wing had already been framed by then.
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Old 03-05-2011, 11:49 AM
  #308
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Default RE: Northstar mods - Tell me what you think

Thanks Cougar, do you trailing edge?

I like the northstar design as i fly out back from a ROUGH fied so no wheels are a bonus (considered seamaster but bored of plank wings). To that extent I plan to fibre glass bottom.

The Polaris is prone to snapping the motor nacelle where it joins the fuse.' Ergo I was going to use CF rods to support it and/or possibly CF from Trailing Edge to motor mount.

Is the USA kit strong (with some CF "seamaster" tail reinforcement). The UK is more expensive but has light ply construction, sheeted wings and different joints. However with the USA kit I could afford a perry pump and negate nose weight.....

Cheers
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Old 03-05-2011, 01:28 PM
  #309
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Default RE: Northstar mods - Tell me what you think

The North Star produced by Balsa USA is strong enough for normal flying using landing gear for land operation. If flown from hard surfaces without the landing gear, then glassing the bottom is required or use the lite ply for the fuselage bottom in front of the step. Since I designed the model over 25 years ago and build about twenty or so North Stars I did not find need to change the design to give it more strength. In case of crush, the fin and the nacelle will come off. I feel that no amount of reasonable reinforcement will prevent that. Over the years I did some cosmetic changes and I placed the elevator and throttle servos inside the nacelle, made the stab with top fin removable and extended the firewall by 1”.Sheeting whole wing will do nothing to strengthen the model, but will add un-necessary weight behind the CG.
I do not discourage anyone to improve the design, just make sure that you do not add more weight to the back of the model.
Good luck.
Laddie.
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Old 03-05-2011, 01:40 PM
  #310
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Default RE: Northstar mods - Tell me what you think

Hello Ladie, thanks for the info. I am leaning towards the Balsa USA kit- price is good and sounds like you think it is strong enough which is good enough for me! More materials are available today- is it worth using CF spars TE of wing and/or in tail fin? Anywhere else?

I think I will order the kit from Balsa USA shortly. Will do the servo mods. Also have decided to use a perry pump as it's weight will be more than offset by reducing nose weight. Also the motor nacelle will be lighter (no fuel tank) and therefore relatively stronger (unless you have any objections!?)

Thanks, Adam
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Old 03-05-2011, 03:31 PM
  #311
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Default RE: Northstar mods - Tell me what you think

Laddie, is that firewall extension now changed in the BUSA kit?

Goldenduff, if you are planning on moving the fuel tank away from the nacelle do not use silicone fuel tubing. It will eventually break down and be difficult, if not impossible to replace. For that I found aquarium air tubing the perfect diameter and easy to form with a bit of heat.
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Old 03-05-2011, 04:55 PM
  #312
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Default RE: Northstar mods - Tell me what you think

This North Star mod should peak someones interest. I enjoy being by the water and recently got struck by the R/C jet bug so my natural progression was to build a 125% turbine powered North Star. I'm hoping to have it in the water late this spring. Power is by a Jet Cat P70 turbine.
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Old 03-05-2011, 05:20 PM
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Default RE: Northstar mods - Tell me what you think

VERY NICE Square Nozzle
I too fly turbines. I like to fly Jetcats as I see you do too.
Please keep us in touch with your progress.
I now have a P120 SE and a P80 SE. If your project works out I won't mind trying something like this off the snow next year.
Again........ Keep us in touch and good luck

Hoss
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Old 03-05-2011, 07:25 PM
  #314
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Default RE: Northstar mods - Tell me what you think

I want a video of that one!!!!!!!!
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Old 03-06-2011, 03:44 AM
  #315
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Default RE: Northstar mods - Tell me what you think

Goldenduff
When and if you buy a Balsa USA Northstar, Just build it according to the plans. You will have great results.
I DID make a small change though. I did as Laddie said,,,, I mounted the elevator and throttle servo's in the nacell.
Works perfect and look at my picture. It is removable.
I also supported the tower with a couple metal rods in case the torque of the motor snaps the tower. The tower is very strong. "Just in case"
Good Luck
Hoss
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Old 03-06-2011, 04:24 AM
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Default RE: Northstar mods - Tell me what you think

Very nice.

I thought with the Perry pump I could carry more fuel- what are average flight times (with few touch and goes and aerobics) will be using a JEN 57.

What size of tank does the balsa usa kit take?

Lil Hoss- are those tension wires supporting your nacelle? Nice touch.

Are the ailerons opperated via torque rods?

Basically I should stop over researching things, get the balsa USA kit, put servos in nacelle, CF rod in vertical stab and don't' bother with perry pump? Glass fibre its hull and go fly?!

As for radio installation I have a decent digital one. Was going to have ailerons (ailervators) mixed with elevator- ?better low speed response and less movement due to combined surfaces therefore less drag.

This arrangement would enable up or down flaps- do these work with deltas or is it best to maintain reflex?

Cheers

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Old 03-06-2011, 04:32 AM
  #317
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Default RE: Northstar mods - Tell me what you think

Now that is some A-1 quality design bashing!

Great job Square Nozzle!
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Old 03-06-2011, 04:38 AM
  #318
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Default RE: Northstar mods - Tell me what you think

I don't think a Carbon rod is nessary in the vertical stab. It is very strong already. The reasons for the tension wire are because a friend with a Northstar was "hot dogging " on the snow and throttleing up and down and ripped the vertical stab off and the running motor tore up his wing.
I am using a 10 oz fuel tank
Don't mess with the perry pump.........Keep it simple.
I did glass the bottom up to the step and painted it. If it scratches,,,I'll just paint it again.
I also went with Ni rod for the ailirons. The yellow tube with the blue one that slides through the center.
Ailvons are nice........But again,,, keep it simple. Build according to the plans.
This is just my opinion, But I had GREAT results

Again,,Good Luck

Hoss
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Old 03-06-2011, 07:36 AM
  #319
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Default RE: Northstar mods - Tell me what you think

Quote:
ORIGINAL: Cougar429

Laddie, is that firewall extension now changed in the BUSA kit?

Goldenduff, if you are planning on moving the fuel tank away from the nacelle do not use silicone fuel tubing. It will eventually break down and be difficult, if not impossible to replace. For that I found aquarium air tubing the perfect diameter and easy to form with a bit of heat.
No. It is still in the same place which is OK.
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Old 03-06-2011, 12:48 PM
  #320
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I am enclosing some old photos I scan from my albums showing just minute portion what was done to North Star design by modellers around the world. Most of the scans are of poor quality, by it give you idea.
First scan at the top is showing 150% version built in Ivory Coast Africa. As you can see, two bottoms are twin powered NS.
Second scan is showing my long nose NS and several NS at the Skymaster Float Fly.
Third scan is showing me digging out what left of my NS. The middle picture is showing 200% NS built by the club member Peter Baab and my 100% un-covered NS and my 50% NS sitting on the top. The bottom picture is from England. I think it is 150% NS.
Two and half years ago the new kid on the block showed up in the form of 29” wingspan all foam version on the NS, designed by Steve Shumate of Washington State. He calls it the Polaris which is still other name for the North Star.
I hope that my NS and his Polaris will continue bringing enjoyment.
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Old 03-06-2011, 01:25 PM
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Default RE: Northstar mods - Tell me what you think

Don't know if I like the mods done to the top one in that last pic![&:][&o]
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Old 03-28-2011, 08:39 AM
  #322
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Default RE: Northstar mods - Tell me what you think

Procastination is coming to an end! I am going to use the J'en 56 from Just Engines (1.9bhp standard silencer, AUW 480g- could inc. output with tuned pipe, are these less reliable and/or harder to tune?). Going with perry pump as the 1.5oz to avoid 16oz in the nose is worth it in my opinion.Will engineer a way to be able to replace the fuel lines (a good tip on here was to use aquarium type tubing and heat to form).

The turbine 150% NS rocks but is outwith my skill and budget, another NS had a rounded top fuse'- looked good and within my limits!

Micro servo for throttle
Standard servo in tail for elevator
Digital servoS for aelevators (torque rods to keep things sleek). May inc. elevator size too.
Standard servo in nose up front for rudder.
Perry pump in nacelle
2cell lipo and regulator to 6v up front for radio.

Had conflicting advice re: perry pump but I cannot and will not but 16oz in the nose (thats 15% of a 7lb bird!!!)



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Old 03-28-2011, 09:05 AM
  #323
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Default RE: Northstar mods - Tell me what you think

I'm the one that recommended the aquarium tubing. Great stuff and easy to form. I used it last a few days ago to install a third line into my Harvard tank for fill/defuel as it had to make a tight curve to the front bottom of the tank, (to prevent interfering with the clunk). Brass would have been extremely difficult to form and even harder to fit into the tank with the clunk and vent lines heading in different directions. The plastic is flexible enough to bend that little bit to go where needed.

It also reduces any possibility of chafing a hole in the tank.

Are you going with a Perry pulse or shaker?
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Old 03-28-2011, 10:40 AM
  #324
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Default RE: Northstar mods - Tell me what you think

Thanks for your tip couger (what bore aquarium pipe works best).

Re: Mr Perry, am going to tap the crank case as have been advised that the two stroker (J'en 56) will not vibrate enough to power the pump. That was the advise of a manufacturer ( I would rather not compromise the crank case by tapping it but if it is the most reliable way then I will).

Any thoughts Perry Vibration v's Pulse on a 2 stroker?


Secondly I have no experience with tuned pipes. The J'en 56 is 480g with silencer and puts out 1.9bhp. I could go with a tuned pipe as power is always good and it shouldn't be much heavier (esp. as I could shift the fuel tank further forward so wouldnt require more nose weight). One of the best things about the tuned pipe is it would increase the chance of the exhuast being the furtherest real point i.e. less cleaning after flying!

Any thoughts on what a tuned pipe does for reliablility, idling, starting, tuning etc
(p.s. whats the difference between tuned pipe or muffler?!)

Love the thread as the nearest club is 50miles away! I fly out back because I crash several times in the time it would take me to get to the club! I mean fill the tank several times!
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Old 03-28-2011, 08:31 PM
  #325
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Default RE: Northstar mods - Tell me what you think

I think you should have enough vibration for a shaker to work. I was lucky with the OS 40 as the rear cover had a boss for tapping a pressure fitting for the pulse pump. A bare rear cover would likely be too thin otherwise.

A tuned pipe is great if you plan to run the motor balls out. By design it is set so that an exhaust pulse flowing down the pipe creates low pressure to help feed the following charge into the cylinder. That increases the power. Unfortunately that only works at one set RPM and you adjust the length of the pipe to "Tune" it to that RPM. Anywhere else in the RPM band and performance suffers.

Besides that, on a front mounted engine you could have the pipe along the fuse. Kind of difficult with the pod mounted arrangement on the Northstar. My advice would be to look at a MACS type muffler as they do give a power boost without being excessively long. I have one on my Harvard II/PC9 with an EVO 46 and it screams.
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