Northstar mods - Tell me what you think
05-22-2013, 11:52 PM
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RE: Northstar mods - Tell me what you think
Hi Lionel,
That is one of the nicest looking NS I have seen! Well done! Please please let us know how it flies- ideally with a video.
I like the curved turtle deck look and the engine pod- any plans or pic of the build under construction?
Do you have two servos for the elevator? I had not thought of splitting the elevator- I wonder if it would improve low speed banking due to the prop wash or is there not enough torque due to the elevator halves being so close to the longitudinal axis?
All the best, keep us posted,
That is one of the nicest looking NS I have seen! Well done! Please please let us know how it flies- ideally with a video.
I like the curved turtle deck look and the engine pod- any plans or pic of the build under construction?
Do you have two servos for the elevator? I had not thought of splitting the elevator- I wonder if it would improve low speed banking due to the prop wash or is there not enough torque due to the elevator halves being so close to the longitudinal axis?
All the best, keep us posted,
05-23-2013, 12:12 AM
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RE: Northstar mods - Tell me what you think
Hi Goldenduff,Thanks, as you probably know, F3A is as much a fashion parade as a flying contest, so the bling has washed off onto my Northstar. The anhedral tail has benefits when the tail is located directly behind the wing in the vertical plane, ensuring that there is always a part of the tail plane outside of the shadow of the wing. On the Northstar I integrated the anhedral for purposes of styling. The attached pics show how I used a single servo with short Nyrods to connect to the elevators, also a couple of pics of the planking. There are no drawings, I made it up as I went.
05-23-2013, 12:33 AM
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RE: Northstar mods - Tell me what you think
Perfect Lionel.
Do you think a servo per elevator half would imrove roll at slow speeds? I'm thnking of high alpha stuff when descending. The prop wash would lend authority to the horizontal tail surfaces but then they are close to the axis of rotation so wouldn't have a lot of leverage......
05-23-2013, 01:33 AM
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RE: Northstar mods - Tell me what you think
Goldenduff,
Sorry, I misunderstood your question.
Ailerons mixed back to split elevators would have to make some difference when the power is turned up, the leverage is small as you have suggested but the elevators are very close the prop, and if you lower the stab to the thrust line as I have done you will be right in the centre of the prop wash.
If you added another rudder above the stab and mixed all rudders and elevators to ailerons it should spin like a turbo lol, just kidding, but you never know :-)
05-23-2013, 03:33 AM
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RE: Northstar mods - Tell me what you think
Hi Lionel.
You created one of most attractive looking NS. I hope that the changes you incorporated into the design work for you. I am sure you will let us know your experience with the model once on the water. I am glad when my design is modified for whatever reason.
Good luck. Laddie.
You created one of most attractive looking NS. I hope that the changes you incorporated into the design work for you. I am sure you will let us know your experience with the model once on the water. I am glad when my design is modified for whatever reason.
Good luck. Laddie.
05-23-2013, 09:24 AM
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RE: Northstar mods - Tell me what you think
Wow! That is amazing. Good luck and I look forward to hearing how it handles.
ORIGINAL: Aussieflier
Hi,I have been following this thread and thought I might bring something to the table.I think that it should be said that good design in modelling also includes the ease of which the model can be built. The designer of the Northstar has taken this into account and as such many modellers over the years have comfortably started, completed and have successfully flown their Northstars. For the more experienced modeller the Northstar's simplicity encourages one to make a few modifications if for no other reason than to build a little bit of ones self into the model. In my opinion I think it a little bold to suggest that Northstar is or was lacking in it's original design. If you were to approach any designer of full sized aircraft and tell him that you intend to build his design 40 to 50% heavier the his specification he would tell you in no uncertain terms that it will not fly. It also needs to be said that since the Sea Dart ,no aircraft company ( that I am aware of )has even tried to get this formulae for an aircraft to work, I think this clearly indicates that some very expert designers have decided that a delta wing flying boat is not an easy task. The Sea Dart design required water skies to get enough airspeed and AOT to lift off, this was all about weight.A few months ago some friends of mine encouraged me to build a Northstar, my background is F3A and so I decided to upgrade the look of the model a little. I would not dare to say that I have improved the model, perhaps I can say that I have prettied it up a little. I have built the model with an electric power plant as was suggested by my friends, this turned out to be the heavy option but I think the power to weight is OK, as I have a great deal more power than a 0.46.The motor is Turnigy 600 1100 1.1KV 50mm, I am running 6S and turning an APC 10 x 7 at 19,000 rpm while drawing 105 amps.The fuselage sides and lower fin are boxed up as per the original plan, the turtle deck, canopy and nose upper are all planked in 1/8 balsa, as is the engine pod. I incorporated the 1/8 balsa fuselage bottom and then fitted a 1/8 ply keel, I then planked the Vee bottom with 1/8 balsa to form a very strong triangular box hull. i.e. All of the Vee hull is extra depth to the model. I also added hardwood strakes to give the hull more lift out of the water as well as better shock absorbing on landing. The canopy is 45mm taller than the original lines of the fuselage. I have more than doubled the height of the step in the bottom of the fuselage, I also lengthened and tapered the wing floats.The Elevator servo is in the engine pod.The fuselage, fin and engine pod are all finished in 1/2oz glass and epoxy, the bottom of the fuselage and floats have the recommended 2 layers of 2oz glass and epoxy. The wings and tail plane are covered in Solartex.The entire model is painted in Createx Auto Air and covered with 2 coats of 2 pack acrylic clear.The entire airframe (including all control surfaces) prior to glassing, covering and painting weighed 1.5 kilos this includes also the elevator servo and 150 grams of cable running from the battery compartment to the motor.After glassing, covering and painting the airframe weighed 1.9 kilos. So all of the finishing including covering and glassing the bottom added 400 grams total. I think I could get that down to less than 300 grams if I did it again.The total weight of the finished model including the 800 gram battery is 8Lb exactly. So it is comparable to a 7 1/2Lb glow model with a full tank of fuel. There is no lead in the nose.A good 0.46 develops about 850 watts at the shaft. This electric setup given an efficiency of only 85% should develop about 2000 watts at the shaft. In the end I think I am about a pound over the ideal weight but with more than double the power.I have yet to fly the model but I should have the opportunity to fly it in a few weeks.CheersLionel
Hi,I have been following this thread and thought I might bring something to the table.I think that it should be said that good design in modelling also includes the ease of which the model can be built. The designer of the Northstar has taken this into account and as such many modellers over the years have comfortably started, completed and have successfully flown their Northstars. For the more experienced modeller the Northstar's simplicity encourages one to make a few modifications if for no other reason than to build a little bit of ones self into the model. In my opinion I think it a little bold to suggest that Northstar is or was lacking in it's original design. If you were to approach any designer of full sized aircraft and tell him that you intend to build his design 40 to 50% heavier the his specification he would tell you in no uncertain terms that it will not fly. It also needs to be said that since the Sea Dart ,no aircraft company ( that I am aware of )has even tried to get this formulae for an aircraft to work, I think this clearly indicates that some very expert designers have decided that a delta wing flying boat is not an easy task. The Sea Dart design required water skies to get enough airspeed and AOT to lift off, this was all about weight.A few months ago some friends of mine encouraged me to build a Northstar, my background is F3A and so I decided to upgrade the look of the model a little. I would not dare to say that I have improved the model, perhaps I can say that I have prettied it up a little. I have built the model with an electric power plant as was suggested by my friends, this turned out to be the heavy option but I think the power to weight is OK, as I have a great deal more power than a 0.46.The motor is Turnigy 600 1100 1.1KV 50mm, I am running 6S and turning an APC 10 x 7 at 19,000 rpm while drawing 105 amps.The fuselage sides and lower fin are boxed up as per the original plan, the turtle deck, canopy and nose upper are all planked in 1/8 balsa, as is the engine pod. I incorporated the 1/8 balsa fuselage bottom and then fitted a 1/8 ply keel, I then planked the Vee bottom with 1/8 balsa to form a very strong triangular box hull. i.e. All of the Vee hull is extra depth to the model. I also added hardwood strakes to give the hull more lift out of the water as well as better shock absorbing on landing. The canopy is 45mm taller than the original lines of the fuselage. I have more than doubled the height of the step in the bottom of the fuselage, I also lengthened and tapered the wing floats.The Elevator servo is in the engine pod.The fuselage, fin and engine pod are all finished in 1/2oz glass and epoxy, the bottom of the fuselage and floats have the recommended 2 layers of 2oz glass and epoxy. The wings and tail plane are covered in Solartex.The entire model is painted in Createx Auto Air and covered with 2 coats of 2 pack acrylic clear.The entire airframe (including all control surfaces) prior to glassing, covering and painting weighed 1.5 kilos this includes also the elevator servo and 150 grams of cable running from the battery compartment to the motor.After glassing, covering and painting the airframe weighed 1.9 kilos. So all of the finishing including covering and glassing the bottom added 400 grams total. I think I could get that down to less than 300 grams if I did it again.The total weight of the finished model including the 800 gram battery is 8Lb exactly. So it is comparable to a 7 1/2Lb glow model with a full tank of fuel. There is no lead in the nose.A good 0.46 develops about 850 watts at the shaft. This electric setup given an efficiency of only 85% should develop about 2000 watts at the shaft. In the end I think I am about a pound over the ideal weight but with more than double the power.I have yet to fly the model but I should have the opportunity to fly it in a few weeks.CheersLionel
05-24-2013, 04:51 AM
#434
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RE: Northstar mods - Tell me what you think
Aussieflier, I was wondering how you had the esc set up for cooling in that beautiful bird. I know with the polaris we had to put the esc close to the battery and had to have a heatsink though the fuse or some cooling vents in the fuse to run air by the esc. I would imagine with the kind of amps you will be running, you will need some good cooling. With all the work you put into that northstar, I wouldn't put it past you to have already installed a radiator.
05-25-2013, 10:14 AM
#435
RE: Northstar mods - Tell me what you think
FWIT, here is how I cooled the ESC without letting air or water inside.
It is a 30x30x6 mm 5 volt cooling fan plugged into a spare Rx socket (find them on Ebay)
It is a 30x30x6 mm 5 volt cooling fan plugged into a spare Rx socket (find them on Ebay)
05-26-2013, 07:31 PM
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RE: Northstar mods - Tell me what you think
Hi Flybyjohn,
I have to say that I spent a few hours pondering the question of how to handle heat dissipation. I didn't want to cut vents into the model so I chose to go with a fan cooled ESC, I also made sure that the current rating of the esc was well above the 110 Amps that the motor can handle.
Below is the spec for the ESC that I chose, as you can see I paid a penalty in the weight department.
I ran the following test:
I put the ESC and battery in a card board box 100mm x 100mm x 200mm and ran the motor for 5 minutes. I moved the throttle between half and full power in 30 second intervals. I used the same 900mm of 12# Noodle wire between the ESC and the motor (as is built into the model) and I allowed the air from the prop to flow over the outside of the card board box with the motor mounted 1metre away. . The air inside the box never exceeded 45Deg C and my ambient temperature during the test was 32Deg C. I also ran the 900mm of 12# Noodle wire through a card board tube and sealed the ends to prevent air flow ( simulating the route to the motor in the model) The wire did reach 70DegC toward the end of the test. At worst, if this particular ESC gets too hot it will start to dial down the available power rather than cutting out or catching on fire. I monitored the RPMs and current drain during the test, full power was always available.
I was a little disappointed that the fan on the ESC is about one mosquito power and moves very little air, however it does seem sufficient and the fan is thermostatically controlled and as such only turns on as required.
SJ PROPO 120A HAWK PROGAMMABLE BRUSHLESS OPTO ESC WITH FAN (4-12 CELL LIPO)
• Load Current : 120A
• Peak Load : 150A
• Dimensions (mm) : 73.40 X 56.2 X 31
• Weight : 166g
• Super Programming System : YES
• High Motor Frequency : 32 KHz
• Power on Reset : YES
• Cooling fan System : YES
• Thermal Protection : YES
• RX Filter : YES
Sorry I was unable to upload a picture of the ESC from the Wholesalers website, I will take a picture of the installation in the model and upload here soon.
Cheers
Lionel
05-27-2013, 10:05 PM
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RE: Northstar mods - Tell me what you think
Skywagn180,
Just reading your original post and note that you are using elevons as well as elevators.
I have been reading up a lot on delta designs and I came a cross some interesting observations.
I think that your elevons are working against you on take off. Up elevon causes loss of lift before it causes the AoA to increase. It also causes drag. Added to the problem is the fact that the tip floats limit the achievable AoA until the hull rises from the water.
I think that your elevons are acting to reduce your lift as well as to increase the drag of your wing as well as tpo increase the drag of your tip floats by pushing them deeper into the water.
Evidently it is a well documented fact that application of up elevon on a delta will cause the aircraft to sink just prior to lifting the nose.
If you have not done so already, it may be worth experimenting on flat water comparing take off characteristics with and without elevons
Cheers
Lionel
05-28-2013, 12:29 AM
#441
RE: Northstar mods - Tell me what you think
ORIGINAL: Aussieflier
Skywagn180,
Just reading your original post and note that you are using elevons as well as elevators.
I have been reading up a lot on delta designs and I came a cross some interesting observations.
I think that your elevons are working against you on take off. Up elevon causes loss of lift before it causes the AoA to increase. It also causes drag. Added to the problem is the fact that the tip floats limit the achievable AoA until the hull rises from the water.
I think that your elevons are acting to reduce your lift as well as to increase the drag of your wing as well as tpo increase the drag of your tip floats by pushing them deeper into the water.
Evidently it is a well documented fact that application of up elevon on a delta will cause the aircraft to sink just prior to lifting the nose.
If you have not done so already, it may be worth experimenting on flat water comparing take off characteristics with and without elevons
Cheers
Lionel
Skywagn180,
Just reading your original post and note that you are using elevons as well as elevators.
I have been reading up a lot on delta designs and I came a cross some interesting observations.
I think that your elevons are working against you on take off. Up elevon causes loss of lift before it causes the AoA to increase. It also causes drag. Added to the problem is the fact that the tip floats limit the achievable AoA until the hull rises from the water.
I think that your elevons are acting to reduce your lift as well as to increase the drag of your wing as well as tpo increase the drag of your tip floats by pushing them deeper into the water.
Evidently it is a well documented fact that application of up elevon on a delta will cause the aircraft to sink just prior to lifting the nose.
If you have not done so already, it may be worth experimenting on flat water comparing take off characteristics with and without elevons
Cheers
Lionel
Well apply UP elevator and you get a down force at the tail anyway.
The only way to help get the nose up on takeoff, without applying a down force is to use a canard foreplane.
I have found that elevons made a huge improvement to the manoeuvrability of my Northstars, and would not be without them.
Maybe Laddie agrees? His next model, the Arrow, did away with the tailplane.
05-28-2013, 12:38 AM
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RE: Northstar mods - Tell me what you think
Would up elevons at take off reduce the high pressure build up under the wings caused by ground effect (water effecti n this case) and there for decrease lift?
I would be interested to hear the effect of decoupling the elevator and ailerons for take off has. Water handling might suffer but if you get up on step quicker it might be acceptable?!
05-28-2013, 01:07 AM
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RE: Northstar mods - Tell me what you think
Up elevator does not change the lifting characteristics of the wing, it changes angle of attack.
If you draw a symmetrical aerofoil wing section and then give up aileron to it what have you achieved.
1, you have reduced the incidence.
2, You have created a semi symmetrical air foil section which now has the lifting bias to the bottom which in turn requires a greater
angle of AoA to achieve the same lift.
3, You have created extra drag.
These are the results of NASA wind tunnel testing, I am not qualified to argue with them.
Non of these effects are achieved when giving up elevator. Up elevator applies a downward force well behind the C of G. in order to increase the angle of attack. Up Aileron applies a downward force much further forward, the area that we are trying to get out of the water.
I was suggesting that up elevator only may be better on take off, elevons added during flight I am sure would be beneficial.
Cheer, Lionel
05-28-2013, 01:34 AM
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RE: Northstar mods - Tell me what you think
If you would like to see some very interesting testing by the experts, Google " Langley Tank Testing " you will see that many transonic jet seaplanes designs were tested.
Two very interesting things can be noted from the testing. Firstly that all of the designs have tails. And secondly that none of the designs ( that I could find) were manufactured.
Cheers
Lionel
05-28-2013, 05:09 AM
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RE: Northstar mods - Tell me what you think
ORIGINAL: Goldenduff
Surely up elevator reduces the ground effect that would aid take off?
Surely up elevator reduces the ground effect that would aid take off?
05-28-2013, 06:11 AM
#448
RE: Northstar mods - Tell me what you think
The Model Aero Polaris Ultra is larger and has a moulded airfoil and reshaped fuse:
http://modelaero.com/Merchant5/merch...tegory_Code=AM
Just picked one up at Toledo this year and maidened it a week ago, (gave my original, flat-winged Polaris to a friend a while ago). Have a float fly this Saturday, weather permitting, so it will see water for the first time. Expect it to work as well there as it does off grass.
http://modelaero.com/Merchant5/merch...tegory_Code=AM
Just picked one up at Toledo this year and maidened it a week ago, (gave my original, flat-winged Polaris to a friend a while ago). Have a float fly this Saturday, weather permitting, so it will see water for the first time. Expect it to work as well there as it does off grass.
05-28-2013, 07:39 AM
#449
RE: Northstar mods - Tell me what you think
ORIGINAL: Cougar429
The Model Aero Polaris Ultra is larger and has a moulded airfoil and reshaped fuse:
http://modelaero.com/Merchant5/merch...tegory_Code=AM
Just picked one up at Toledo this year and maidened it a week ago, (gave my original, flat-winged Polaris to a friend a while ago). Have a float fly this Saturday, weather permitting, so it will see water for the first time. Expect it to work as well there as it does off grass.
The Model Aero Polaris Ultra is larger and has a moulded airfoil and reshaped fuse:
http://modelaero.com/Merchant5/merch...tegory_Code=AM
Just picked one up at Toledo this year and maidened it a week ago, (gave my original, flat-winged Polaris to a friend a while ago). Have a float fly this Saturday, weather permitting, so it will see water for the first time. Expect it to work as well there as it does off grass.