N5/N5c Tips & Tricks

N5c Manual v3.0

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Stainless Steel Bolts – (Added 8-8-2011)

Do not use stainless steel bolts on portions of the kit that utilize a pinching mechanism. Examples below.

  • FBL Head Block
  • Main Shaft Pinch Collar
  • Engine Fan Hub

Why not use stainless steel bolts?

Stainless steel screws are much softer than hardened steel screws. When used in a pinching application the bolt may stretch and cause the pinching mechanism to not securely grip the mating part. Recently a customer complained of the main shaft collar slipping, after inspecting his helicopter I noticed he had replaced the 2.5mm hardened steel bolt with a stainless steel bolt. I immediately changed the main shaft collar bolt back to a hardened steel bolt and the problem was gone.

 

Manual Corrections -

Page A9 – Clutch Bell Assembly, Lite part number should be 200-404

Page A22 – Tail blade grips for belt drive tail system should be leading edge controlled, not trailing edge controlled

Page A22 – Tail Blade Grip Bolts and Nylock Nuts not shown. Part numbers are 100-316 M3x16 and 100-351 M3 Nylock Nut

Page A24 – Main Boom Clamp, Lite part number shown as 115-111. Correct part number is 115-112.

Page A38 – Crown Gear part number not shown. Crown Gear part number is 610-136

Page A50 – Head Block Jesus Bolt Part Number shown as 100-320. Correct part number is 100-320A

Page A56 – Blade Grip Bolt part number displayed as 100-435. Part number should be 100-435A

Tail Output Shaft Positioning -

Screw in 3mm cup point set screws so they are very close to contacting the flat spot on the tail output shaft. Slide the tail output shaft all the way to the left side of the tail box and secure the set screws. Doing this assures you will have the correct 5 degree offset in your tail blades when all tail bell cranks are set to their correct 90 degree position.

** Note ** – You do not need the entire throw range in order for the tail to counter act torque correctly. With the Futaba CGY750 my throws are set to 130% on both sides.

Canopy Mounting -

If you mount the N5c canopy without modifying the canopy mount holes you will notice there is a small amount of tension to allow for clearance of the main gear. If you do not like the look of the canopy while mounted like this you can trim 2mm of material from each hole to relieve the tension and the main gear will still clear the canopy as long as the trimming is done correctly. See picture below.

Carbon Tail Push Rod Assembly -Page A23 & A30

Carbon tubing consists of glue and stranded carbon fiber. If you put too much force on the ends of the tube you will fracture the tube and the threaded rod will come out during flight. The key to building this correctly is to use a brass collar (4mm ID x 5mm OD usually come with 690 or 710mm blades) as a support for the carbon tube ends. Glue the brass tubing over the ends of the carbon rod and you will never have an issue. I’ve seen other Synergy owners use shrink wrap with success. In the future I do plan on offering a rod which travels the entire length of the carbon tube in order to make assembly easier.  I apologize for not including this in the kits.

CGY750 – Want Faster Cyclic Response out of N5c?

If you find the cyclic percentages are very high and the roll and tumble rate are still not fast enough, there is an option! Instead of using the short ball(107-106) on the inner swash, try using the long ball(107-108). These are the balls that connect to the pitch links.  IMPORTANT!! If you perform this modification, make sure you trim approximately 1mm of threads off the long ball with a file or Dremel Tool. If you do not trim the threads they will bind with the swash ball housing causing the swash to feel very still.

Another option is to try different set of blades. Unfortunately not all FBL blades are created equally and some have their limits to which no matter how high you turn the swash AFR’s the helicopter will not move any faster.

Building the Tail Box -

Specifically the tail box flange bearings. Due to normal machining tolerances, the tail box flange bearings are either a press fit which will required an arbor press to install or they are an interference fit which you can just press in with your thumb.  If the flange bearings require an arbor press to install you do not need to glue the bearings into place. If the flange bearings are easily installed/removed you will need to use thin CA to create a press fit. In order to do this, simply apply thin CA to carbon hole and let it wick into the layers of carbon. After the CA is dry, test fit the bearings into the tail box plate and vertical fin to see if you have a proper press fit.

 Original N5 Tips and Tricks -

Below you will find information concerning the equipment I use, my personal rotor head setup, and some build tips.

My rotor head setup is geared toward a balance between smooth tracking and quick cyclic response. Below are the mechanical settings I use on the N5 programmable head. Settings in the manual will give the novice to intermediate pilot a very nice and stable helicopter.

  • Bell Mixer – Both Bell and Hiller on the inside position (illustration below)
  • Seesaw/Flybar Carrier – Center Position (illustration below)

Main Shaft Pinch Collar -**CRITICAL**

Some of the Main Shaft Pinch Collars are tapped on both sides. This will cause the pinch collar to not grip the main shaft tight enough. Please check your pinch collars to make sure that the front side is a 2.5mm through hole and the back side is tapped. If not it is very easy to run a 2.5mm drill through the front side of the pinch collar.

The pinch collars are anodized from the factory, this is good and bad. The aluminum will not oxidize but the coating can allow the pinch collar to slip under heavy loads. If you find your N5 has a small amount of up/down movement in the main shaft, sand the inside of the pinch collar to remove the anodize coating. After sanding your pinch collar should never slip again.

Head Axle Sleeve

I’ve noticed quite a few people with low head speed wobbles and there are a few reasons for this. The stock dampers are very tight in the head as well as on the spindle. The main blade axle must be greased so that it can center properly during flight.

Stock from the factory, the N5 head dampers are compressed by about 1mm. To remove this compression, replace the 1mm shims in the head (between thrust bearing and radial bearing inside the blade grip) with either .5mm shims or .75mm shims. This will allow you to run lower head speeds without the wobble.

I’ve found a few helis out there where the head button bolt was pressing against the main blade axle sleeve! If you are going to run the main blade axle sleeve make sure you do not over tighten the head button bolt, it will run into the sleeve if tightened too much. I personally have stopped running the sleeve because I didn’t see a difference in performance with the sleeve and it can actually hurt your performance if not centered properly. My suggestion….. ditch the sleeve!

Pitch Slider Lock Washer Tips-

The lock washer works very well if you follow these simple tips.

  1. Flatten the lock washer in a vise or arbor press.
  2. Press the lock washer on to brass pitch slider using a socket with the same outer diameter as the lock washer. Be careful not to press the lock washer on too far as it will make the bearings bind.
  3. Apply medium CA in between the teeth of the lock washer.

Things to check if you have a high frequency tail vibration?

  • If you’ve had a crash or touched the tail on the ground, check your tail hub and tail output shaft to see if they are bent.
  • Make sure your bearings are tight in the vertical fin and opposing tail plate, use CA to secure them.
  • Do not over tighten the rear boom clamps. These clamps are very strong and the gap does not need to be closed.
  • Tail output shaft should not have excessive play within the flange bearings. If you think there is too much play then I would recommend green or red loctite to secure the shaft within the bearings. Make sure you take the tension off the belt before securing the shaft into the bearings.
  • Tail Blades – I can’t stress using quality tail blades enough. The N5 has a 4.66:1 ratio which means at 2150 on the head, the tail is spinning 10,000 RPM. If your tail blades are slightly out of balance or the CG is off, it will show up as a vibration in the tail.
  • Through experimentation, I have found that slightly longer boom supports can make the tail rotor a bit less susceptible to high frequency tail vibrations. We will include these in future kits.
  • Engine vibration can transmit high frequency vibrations to the tail. If you’ve had a crash, make sure you dial indicate your crank shaft to make sure it is still straight
  • Most importantly if you hear a high frequency buzzing coming from the tail at higher RPM’s do not fly the helicopter! Land and figure out the cause. This type of vibration will lead to other part failures.

Belt Tension -

Too much belt tension will create a lot of drag in the tail drive system. Too little tension will create belt slapping on the boom. The N5 does not need an ultra tight belt, try to achieve a medium belt tension that does not cause boom slapping or create excessive drag. The N5 belt has an XL tooth profile so skipping teeth and slipping should not happen. If the belt is setup correctly you will not even know you are flying a belt driven tail. After flying a belt driven tail on both my Logo 600 and my N5, I never want to go back to a torque tube. The simplicity and durability are unbeatable.

Engine & Clutch Stack Alignment-

If the clutch stack is not aligned properly you may damage your start shaft. Typically the 8mm portion will crack due to stress from misalignment. Mount your engine and clutch stack into the frames as shown in the instructions. Leave all bolts lose at first. First tighten down the four engine mount tab bolt. Next you will want to check your main gear mesh. You can rock the engine slightly toward or away from the main gear to achieve a slightly better mesh. Once you are happy with the main gear to pinion mesh, tighten down the eight motor mount bolts to the frame. Once the engine is secured you can now check the start shaft for free rotation. Move the clutch stack slightly fore or aft until you feel the start shaft is free within the one-way clutch bearing. Tighten down the four clutch stack bearing block screws and you are done.

Auto Hub-

Do not try to remove vertical play, this play was designed into the unit to allow the auto hub to float and spin freely. Removing this play will affect your auto-rotation performance. Also the auto hub can be installed as it appears in the manual or flipped upside down in case the one-way is installed in the opposite direction.

Auto Hub locking up – This is a known issue, some people are experiencing this and some are not. If you are experiencing this, here is a list of things to try.

  • Clean all of the grease out of the one way and apply a light oil
  • Lightly sand auto hub inner sleeve until OD is between 11.96-11.98mm
  • Loctite inner sleeve to main shaft (helps close the gap between OD of main shaft and ID of auto hub sleeve).

Metal Bearing Blocks -

Be sure to lightly heat the bearing blocks before inserting the main shaft bearings. If properly heated the bearings will slide right into the blocks without any force. Once cool they will be perfectly seated. Using an arbor press will make life much easier when installing these bearings.

Elevator control arm set screws -

Either use flat point set screws or grind a flat on the included cup point set screws that come in the kit. Cup point set screws may allow the elevator control arms to rotate slightly after an aggressive flight. I am working with the factory to make sure the correct set screws are included in the future.

Most recently I have started tapping my inner and outer elevator arms out to 4mm. The 3mm set screws will work but as soon as a blade touches the ground, you will notice the helicopter is out of trim on the elevator.

Clutch Liner Installation – All current kits come with clutch liner installer

Follow these installation steps -

  1. Trim an 1/8 inch of clutch liner off the end of the material
  2. Insert the clutch liner into the clutch bell to test the fit
  3. Wrap the clutch with one layer of electrical tape
  4. Use Medium CA or JBWeld to secure the liner
  5. Insert clutch into the clutch bell
  6. Let glue dry
  7. Remove clutch from clutch bell
  8. Sizing may be needed in order to allow the clutch bell to spin freely on the clutch. Use a Dremel tool with a large fine grit sanding drum to remove material. A lathe would be ideal but I know most people do not own a lathe.

Start Shaft Hex Adapter -

  • Some of the start shaft hex adapters are a little tight on certain starting wands. If you have one of these, take a measurement with your calipers and send me the details.

Engine Removal -

  1. Remove the muffler
  2. Remove fan shroud
  3. Remove four engine tab bolts
  4. Drop motor down until it clears the clutch
  5. Rotate motor left or right and remove from main frames.

Tail Pulley -

Please remember to Thread lock on the Black tail pulley set screws.