oxyfx

Hello,

I am in the middle of building my 1st Northstar from Laddie's kit. The past weeks I spent so much time on this forum - going back to 2002 and reading all the possible information on the Northstar, construction, flight, performance, etc. I really think almost everything was covered, and for some the following questions may seem duble posting - but the technology changed so much over the years, new engines came to existance, etc.

First question:

I read that the mostly prefferred engine is the Webra 50. I plan to use an OS 50 SX Ring, which has the same performance, but 50 grams (about 2 oz.) heavier. Does anybody has experience with the Northstar and this engine? I use this engine in a GP 40 size ultimate, with a 12x7 prop and it works well. This kit however calls for a 10" prop and the only recomended 10" prop is a 10x8. Will it not spin on the higher RPM range with this prop?

Second question:

In some posts I read that it may be a good ideea to use separate servos for each of the ailerons. Does this still stands? In this case how is the extra sevo connected to the receiver? Through a Y cable or on a separate channel?

Third question:

I plan to use Futaba 3151 Digital Servos. Is this an overkill?

Fourth Question:

When fibergalssing the bottom of the hull, (I will use 30 min epoxy) do you first fit the cloth on the surface, and then apply the epoxy over it till it wets the cloth or it is preferable to apply one layer of epoxy on the surface, wait till it cures, fit the cloth and apply a second layer of epoxy?

So far my model is built as per the instructions, I thought a lot of moving the gastank to the middle of the plane, but finally I decided against it, I will build it just as the description says with an 8oz. tank. The only modification I made was epoxying the inside bottom of the hull to give it additional strenght and possibly water resistance.

Thank you,
Oxy.

jeffo

My Feedback: (68)

Ox-
Your O.S. 50 will be great with a 10-8 prop,I'm running a Magnum 46 with a APC 10-7 and it hauls.The biggest thing is you want the most powerful 46/50 size engine you can find.If you go to a 60 you'll have to add nose weight to counter it and it defeats the purpose.
Servos is just preference,I got Futaba standard servos and they worked well for years.Don't use Hobbico-my experience is water ruins them,Futaba,JR,Hitec are a better sealed servo.
I like all my servos internal,I really don't like them being exposed to water out on the wing..If you set it up like the plans show (internal nyrods to all control surfaces)you'll be smiling.Some guys set up the gas tank on the C.G. with a perry pump works great,but not necessary.
As for fiberglassing the bottom of the hull-Do your self a favor and use 1/8 lite ply no glassing.If you fly your plane in the winter and land some icy snow you destroy the bottom of the hull.Happened to me and a couple guys in the club.I lite plyed the bottom of my hull and never had a problem since.
What ever you do on your Northstar is what you want.There is a lot of opinions out there and there really is not a right or wrong answer.The main thing is to build it and have a ball.
I love mine so much I'm building a 150% Northstar with a O.S,160 and should be ready by spring.
Good luck OX
-Jeffo

Newc

I agree with everything that jeffo says - based on my experiences with four Northstars built and flown with various mods - including the use of something other than fiberglass on the hull. I use balsa cross grained in two layers - sort of a balsa plywood - to save a bit of weight, but his use of lite ply in that area is probably just as good. Good decision to use epoxy inside for water resistance. Do it everywhere you can get to inside, including the inside of the sponsons and the inner hull before putting the top sheeting on.

Couple of other suggestions I have are….Since nose weight will be required, I hollow out the nose cone and fill it with molten lead to get the weight as far forward (And therefore requiring less), and then bolt and epoxy the nose cone on. Bolt isn’t a problem, since weight is needed anyway. Also, put the servos as far forward as possible and reinforce the bottom and rails of the servo area, again keeping in mind that weight needs to be added in the front anyway. I have included a couple of pictures that show how I ensure that the controls are very precise by placing Nyrod braces as close to the control surface as possible. And take a look at the additional two attached photos that show a couple of other mods that I think are beneficial.

simhatus

Hi

In answer to question 2 yes use separate servos into (i'm assuming your using fubtaba as thats what servos you mention) 1 and 6 and use the flaperon mix, leave the flap trim inhibited. then use elevator - flap mixing (2-6) to use the ailerons as elevons. This vastly improves its handling as the elevator dosn't always work to well at certain attitudes.

I used 3001 servo for ailerons and elevator which seem fine.

Simon

LADDIE

OXY

I designed the North Star 21 years ago. Since then lot changed, but I feel that basic design is sound since over the years, hundreds and hundreds were built. Any .49-.50 engine is fine. My original N/S was powered with OS .35 plain bearing glow engine. Replacing front balsa bottom with 1/8� lite ply is good option. The weight penalty is minimal since you will not have to use as much lead in the nose. Mount the servos as close to the nose as possible. Here is the picture of mine two N/S. One with .45 glow engine and other with AXI 4120/18 electric motor. On the electric powered model I raised motor thrust line by 2-1/4� with no ill effect on handling qualities. The flying weight is 6.5Lbs. The electric version is slightly slower then glow version, but not much.
The modes done by News are good ones. Specially, adding sub-rudder at the bottom.

oxyfx

Thanks, guys, I feel honored by the quick responses. You deserve some pictures. Please click on the link below to see some pictures of the construction:

[link=http://www.ngctech.com/photoalbum/thumbnails.php?album=51&page=1]Northstar Construction[/link]

For some of the mods above it is already too late. I already sheeted the bottom with the 3/32 balsa. Regarding to this mod, I could probably buy from the local hobby store some 1/16 birch ply and I would probably be able to cut a one piece front bottom to epoxy it on the already sanded balsa. If I do this (since it is only 1/16) will it change any of the flight performance?

Also if I apply this ply on the balsa, will it still need fiberglassing, or painting it with epoxy for waterproofing would be enough?

I already cut and sanded the ny tubes for the aileron and rudder - so I can't do that mod. I've seen the triangle under the nacelle, and thought that I will apply that.

How about the question in the original post - using a fifth servo to have a separate servo for each aileron?

Tahnks again,

Oxy.

Newc

Laddie - Good to see you putting in some comments on these boards about the plane you designed. Thanks for the comments about the mods that I have been doing. You may recall from the 2002 Skymasters Float Fly at Island Lake, MI that my brother Bob and I were pitted right next to you and I was the one that had the folks take the picture (attached) of you with all of the Northstars there. The camouflage one and the yellow and orange one are the ones that were in the pictures in my earlier post. At one time you commented that you hadn't seen a Northstar do some of the stuff that mine did, and the reason is due to the increased rudder and ailerons.

jeffo

My Feedback: (68)

Ox-
Go ahead and put the ply over the balsa,no glassing will be necessary.you basically want a hard shell.5th servo is completely up to you.If your into servo mixing
go for it.I'm not that sophisticated.
Laddie if your out there-I was wondering how much effect does the upper fin have.I'm building a 150% northstar and have a height issue in transporting.I wondered if I put vertical wing tip stabilizers on will it produce the same effect.My guess it helps in low speeds.I have seen a Northstar pic with the upper fin completely eliminated.

LADDIE

NEWS. That was great photo. I had it enlarged and framed. I can not believe it has been over 4 years since that event. See you at next float fly.

LADDIE

jeffo
I would prefer if you keep top fin, but make it removable for transportation. You can eliminate top fin if you want, but more likely at the low speed the wing will start rocking from side to side. Adding the fins to the wing tips will definitely help.
Laddie.

oxyfx

Ok,

So, the 1/16th ply is on the forward area of my Northstar - before the step. It is in one piece, and the grains are going by the lenght of the craft. I figured since the Balsa's grains are across, going by the lenght with this would add to the strength. I don't believe this is birch, because it is really strong. I barely was able to sand it flush with the 100 sandpaper. It is in one piece and I extended it to go and cover the bottom of the nose cone. That should give extra strenght to that joint as well.

Now the question - Should I cover the same way the back of the bottom as well, behind the step?

Simon, thanks for the mixing notes, I am using Futaba, and I am yet to decide which way I go. I am still thinking that this plane will give housing to an onboard wireless camera where the camera should sit in the coockpit. The transmitter, camera, battery probably would be extra weight, so I may go with 5 servos only. This is something I still have to decide.

evan-RCU

Mine, which was a pre-updated version used aircraft ply forward of the step and I put two layers of lightweight glass over that with proper fiberglass resin. 6+ years later and it's still in excellent condition, though I have patched some deep scratches.

Newc

The plywood over balsa ahead of the step is a good modification, and doing the same behind the step is not needed. In fact, I wouldn't, as it would only add unnecessary weight where you don't want it - in the rear. Keep in mind - since you mention the grain of the plywood - that it consists of layers of wood with the grain of each layer perpendicular to the next one.

I have built a number of Northstars and have never felt the need or perceived a benefit to individual servos for the wings. I make that modification on other planes, but not on the Northstar. I do, however, make the ailerons the same width the entire width of the trailing edge, not tapered to the outside as in the plans, as in the photo. This gives a greater roll rate and enhanced control.

MalcolmL

Hi - came across your post in error (I think !) but found it interesting. I can answer some of your queries as follows :-

1. I used an OS SX 50 ring engine - it flew great with that - maybe needed more weight in the nose than with the Webra
2. Separate servos for ailerons are better
3. Nothing wrong with using digital servos - this plane deserves the best
4. You can also use super glue on the cloth - quicker but smelly - take care not to glue yourself to the model - then a thin film of epoxy. But DO toughen the bottom - I hit a submerged branch once in a landing; and often nudged the "bow" onto the bank after a landing for retrieval; so the bottom does get worked hard.

MalcolmL

jeffo

My Feedback: (68)

Here are some pictures of me and my buddy Davey flying our Northstars in action.I could never understand why put landing on.I take right off the grass.Mine is the Gateway computer box scheme.
-Jeffo

Newc

jeffo - Love the pictures! As a result I am also posting one from 4 1/2 years ago, and they are all still flying. Is your buddy an old motorcycle rider? I ask because he seems to be giving his a kick start!

oxyfx

Simon,

I used 5 servos as you described. What ratio did you set up the Elevator-Flap mixing? Is something around 30-40% enough or sould one go higher? Also on the futaba radio I am using allows me to set up airbrakes as well. Would that make any difference in landing? Slowing down the craft for landing? In the manual it says that this craft doesn't really want to slow down....

Thanks, Ox.

Newc

The Northstar wil slow down to the point that it will do an excellent elevator all the way to the water. Simply reduce power and apply up elevator and the plane will almost stop in the air and then flutter down like a leaf if properly balanced. I have landed on water with an angle of attack that's close to 45 degrees.

simhatus

Hi

When i took the pod off my north star i decided to experiment with a vtail twin engine version, which so far hasn't been a great success, but i will try it again, think it was just so far out of trim the as soon as it took off it dived back into the water.

Just looked havn't still got the origonal set up the default for that mix is 50% on my transmitter, i don't think i altered it. But i am sure it was about 1/2" movment each way.

The north star does need lots of room to land but can be flared out almost to a standstill by keeping the nose up with the tail just out the water and then gently drops into the water, it will land at speed fine also.

Simon

cjdscratch

I would like to build a scaled down electric version of the North Star. Has anyone tried this? I would like to build one that came in at 20-26oz AUW with a 480 brushless motor and 3 cell lipo. Any input would be appreciated.

Chris

werlec

cjdscratch,

Take a look in park flyers at rcgroups.com - do a search on twinkle - you might see something you are interested in. It's a little smaller than 20 oz - but you could scale it up. I've built one - but I haven't flown it yet.

Erle

LADDIE

The North Star does not need lot of room to land. There are several ways to shorten the landing. When there is not that much room to set up for landing in the straight line, I reduce the power and initiate the landing while going down wind maybe from the 100 ft. high. When the model is straight in front of me going down wind, I cut the throttle to idle and initiate the turn into the wind. I continue turning until the model is line up with the runway. I the turn, the model slows down much faster then in the straight line. By the time model is 3 to 4 ft. high above ground it is lined up with the runway.
Even when there is enough room to land, I go for landing in the straight line but instead of using the elevator by it self to control the descend I cut the throttle and start raising the nose. The model will slow down nicely and if it looks like I will be too short I just add the throttle and lower the nose. This way I am controlling the landing angle precisely until the model in on the ground or on the surface of the water.
Below is my electric North Star.

griz

I saw somewhere in a post to use Kevlar instead of glass on the bottom of the Northstar. I have yet to get to that point on mine, but I have used it to patch cracks on some of my other planes. What a difference there is. I felt is was easier to work with either with epoxy or with resin. Obviously epoxy would be lighter. I didn't weigh the two to compare but I could feel the difference just holding the two in my hands. With the properties of kevlar in mind I don't think there would be any problems on any surface. Kevlar is easy enough obtained at the junk yard and for free. I just went down and asked and they gave it to me. I didn't even have to cut it out of the car!

Flipper

My Feedback: (3)

Newc, I bought one of the new OS .55 AX's that is the same size and bolt pattern as an OS .46 FX or AX. That should make mine scream this year at the lake. It has a huge muffler but I think if I use the Macs pipe that I have on the .46 it should weigh about the same. Should be up at the lake flying more this summer and hunting Muskies! Jeff

Newc

Flipper - Sorry for the delay in responding, but was out of town for a couple of weeks. Are you the Northstar flyer on the other side of the lake at the home that I know so well? (OOOPPPSSS! Just saw the 'Jeff' signature, so now know for sure who you are) Don't recall seeing any of your earlier posts on these forums. We have snow on our pier right now, but hopefully I'll have my retrieval boat in soon and then can get back to flying. I'm converting a bunch of planes to the Spektrum system to ensure no interferrence at the lake (at least one more flyer in our area these days), but haven't yet done so on my Northstars. It's almost time for the first flight of the Nomad!