This article was submitted to me by Kent Wien of New Jersey. Kent is a field representative for Hirobo and an extremely capable Tsurugi pilot. It was his demonstration of the model to me over two-and-a-half years ago that got me hooked on helis again. Kent asked if I would like to hover his Tsurugi to which I eagerly answered yes. Less than a minute later I was swooping around 3 feet off the deck in tight high-speed figure-eights while Kent tried not to let his anxiousness show. Two months later, I was also an owner of a Tsurugi and finally on the road to being a decent pilot myself.
Everyone who has seen a Tsurugi fly comments on the smoothness with which it moves. It looks solid in the hover and appears to groove like a pattern ship in forward flight. I feel confident in handing the transmitter to relative neophytes for a test hover of my machine, knowing that it is not going to bite them with twitchiness.
Additionally, this kit cannot be assembled improperly. You do not need a hammer for construction and certainly no grinding. The components are extremely reliable: no chewed up main gears, no fractured tail rotor control rods, no engine alignment errors. If you follow the additional information given below, you can build a Tsurugi with the same level of performance as if an expert custom built it.
Finally, a big thank-you to Kent for taking the time to share his thoughts with everyone. It takes an effort to "put pen to paper," and every secret shared means a better chance of success for everyone.
OK, here goes...
I made this generic so I could post it on Chris's web page. There are some items which I may have already mentioned with you guys but I wanted to include them here. Let me know of any typos or something that is not clear. You guys are the editors!
The long awaited step by step notes of the manual...
Get out the manual and follow along... :-) Shades of Romper Room
First a general note: clean all new screws with alcohol and a paper towel before using them. You can do this as you go. This removes the cosmoline (a rust preventer) which really allows the Loctite to stick. Also buy some hardened allen drivers (not WIHA or any ones that are black). KSJ makes a good set. You will NEED the 1.5mm, 2.0mm and 2.5mm drivers. The 3.0mm driver is good for the blade and engine bolts but it is optional if you want to save some money. They sell for around $10-$15 each.
Each step has the time listed that it took to accomplish the entire step. Note--I was also watching TV while doing this and cleaning every single screw with alcohol. Your times may vary :-).
Do not epoxy the paddles onto the flybar. Just screw them in an equal number of turns until they become nearly bottomed out, but don't go too far. Also, if you intend on doing some 3D flying, pull both weights out by drilling and tapping the weights and then inserting the appropriate tap (I use a 3mm tap from Dubro). If you elect not to pull the weights out the machine is very stable and is great for AMA Class 1,2 and 3. You would need to pull them out for FAI due to the new rolling stall turn. It is still very stable with the weights out, even in fast forward flight.
If you are running an O.S. .61 SX or RX you will notice how smooth the engine is in a Tsurugi compared to the X-Cell with the same engine. However, to make it even more smooth, a friend in Ireland has come up with the following based on vibration testing he did with some special equipment. He was using a WC motor but the same mod works well with a non WC SX or RX. Take a 3mm x 14mm bolt and replace one of the 3mm x 8mm flush-head screws that come in the kit to hold the fan on the hub. Use a 3mm locking nut on the other side and bolt it together. When mounting the fan to the engine align the keyway at 12 o'clock while looking at the front of the engine and put the heavier side of the fan at 3 o'clock. This will give you a smoother Idle and transition... It works, believe me! It helps offset the heavier unbalanced crank. I also raised the exhaust timing of the SX to the top of the engine case which provided more power and a smoother running engine. If you have the original SX and want to tackle that let me know and I'll explain in greater detail. The WC engine already had this done. (email Kent at veryjr@aol.com)
Before threading in the balls pre-tap the plastic swash plate with a 3mm bolt. This makes it much easier. Also, pay attention to the sizes of each ball. Glue the radius pin and the short balls into the plastic portion of the swash plate assembly with Polyzap (CA) or a small amount of JB Weld. It will loosen over time if you don't.
See step two about installing your new balanced fan. Take the carburetor off and insert a toothbrush (the tail-not the head) into the opening to prevent the crank from moving while tightening the nut. Do not Loctite the nut. Just tighten well and you won't have a problem.
follow the instructions about trimming. They want you to trim the piece that holds the fan together nearest the carburetor. This makes it much easier to get the shroud on and off. There are still plenty of screws holding the shroud together. Part 2 (4 minutes): A dial indicator is not necessary for this machine. You may want to use some green or blue Loctite at the base of the clutch shaft to hold the bearing of the clutch bell to the shaft. Be forewarned however that it will be difficult to get the clutch bell off in the future. The advantage is that you will never have the bearing spin on the shaft and (over a long period) cutting into the shaft. The disadvantage is in disassembly. It's up to you. I prefer to do it here and on the bearings that support the tail shaft (you have to disassemble the tail case to do this). I don't Loctite the main shaft however. Just the fast moving shafts AND the 10 bearings that support the levers between the side frames. See steps 8 and 9. These don't have to be disassembled often and I highly recommend green Loctite here (Loctite 290). It eliminates play since the levers can't move side to side. Green Loctite is a very runny type that is used for shafts and bearings. You can even Loctite a bearing that is already on a shaft by using a small point (like a needle) and the Loctite will wick between the bearing and the shaft. This Loctite can also be used in place of blue Loctite for screws if you just want to buy one type.
I definitely Loctite this shaft and the gear on the shaft (important) since it almost never needs to come apart. I've never bent or damaged this shaft. And you won't wear out that gear.
Pay special attention here to the little indentation circled at the top right of the page on the bearing blocks. If you put it in backwards you will have too much play in the main gear to clutch bell gear and strip a main gear in the first 30 seconds. If you put it in correctly the gear will almost last forever (except in a very bad crash).
Loctite these shafts to the bearings like I mentioned in step five. You may also want to JB weld the 2.6 X 6 flush head screw to the lever shaft A. Some people do this. I simply clean the screw really well and use Loctite here and I have yet to have a problem. Again, I've never had to take this part apart, even in a bad crash. At the bottom of the page be sure to understand the difference between the EX balls and the standard balls. The EX balls are countersunk and must go where shown to clear the start shaft one-way bearing.
This tip will save you some grief. Mount the throttle servo on the outside of the frame so you can remove it easier. This will prevent you from having to split the side frames to get the throttle and collective servos out.
The collective servo should go where the instructions say-on the inside. You can still remove it now that the throttle servo is spaced apart slightly.
I assembled everything using Loctite without doing a dry run like it says. I hate to do anything temporarily because it is too easy to forget to Loctite something. The alignment turned out fine. Ever so slightly off when put on a flat table but nothing to worry about. You can't build a shake into this machine. It has yet to be done (tracking of the blades excluded).
Always use Polyzap (CA) glue on bolts that go into plastic. No glue needed on the 4 screws that hold each servo on however.
No comment here. Just clean the screws.
Clean the screws that hold the 3x22mm and 3x33mm posts and Loctite well. It's a pain when these come loose because it is hard to get to the lower 33mm cross members when you have a gyro sitting right there. When you get to installing the radio take note of the following: I mount the gyro up front which sits partially over the lightening holes. I don't mount it on the gyro tray for balance purposes and to keep the gyro away from the oil, dirt and vibration of the engine. In front of the gyro I mount a Strong Box from LDM technologies. It holds the gyro controller if you have one, the receiver, a battery monitor and a bunch of wires. Your U.S. hobby shop should be able to get it. It's the small one (they make two for the airplane people).
When using a piezo gyro don't worry about stripping this gear. You can't do it! At least I haven't been able to break it. This is a very strong part, so spin away!
I highly recommend the slipper clutch for autos even if you are a beginner. It doesn't rob power and helps keep your tail straight when doing autos. I use a bolt with a long shank on it (I think it is a 3 X 25) and then I ground the tip to a point which makes it easier to get through the hole. After it makes it through, I cut the bolt off with my $49 cordless Dremel and Dubro cut off wheel.
Again, I make sure the bolt holding the head on has enough of a shank (non threaded part) to hold the head on. I've never seen a Tsurugi head come off but I've seen a couple of other helis "lose their head" because of a non shanked bolt.
Don't spend too much time getting these perfect. Each one is going to be adjusted at the end of these tips under "Optimum Setup for 3D". Remember, when putting a ball link on a ball the Hirobo label faces outward. This is not mentioned in any Hirobo manual but it increases the life of the ball links.
Don't make the clunk too long. Have it rest in the middle of the tank. Make sure your vent is as close to the top of the tank as possible. You may need to add a 1/4" of tubing to get it really to the top.
PLEASE mount your skids so they angle backwards. This helps the heli from tipping on its tail with the blades folded backwards and it looks good! Note that the center of gravity for the model is at the main shaft so with the skids angled backwards this puts it right in the middle of the gear.
No gluing involved here--really simple eh? If you have to replace the shaft heat up the bearings and slide the bearings off (be sure to take the rubber grommets off first). If you have trouble getting them off, put the bent up assembly in the oven at 450 degrees for 15 minutes. When putting it back together on the new tube use a little bit of green Loctite. (The amount you decide to use is directly proportional to how hard it was for you to get the previous tube drive apart!)
These control guides shown are from the original Tsurugi. Note that you now have two holes in each control guide. Use the outer hole. I don't glue these on the boom--they are tight enough.
I unscrew the tail case and Loctite the shafts to the bearings. Check to make sure there is enough grease. The RC car guys use this kind of grease if you need more. See the little box in the middle of the page? Put these screws so that the heads are near the center of the tail rotor. This is so that centrifugal force will only hold them in--not tend to fling them out. Also make sure you take the pitch change mechanism completely apart and Loctite where the short funny looking screws go into metal (after cleaning) and Polyzap or CA where the screws go into the plastic. This is very important!
I polished the boom supports when I first built it. I now use some carbon supports that are amazing. Very nice. Get in touch with Chris to find out where to get them.
This is self explanatory.
I did not find the tail balancing to be necessary.
See step 27.
Disregard and follow the setup instructions at the end of these notes.
Trim the 14 inch flange down to about a 1/16" or less on the back side of the canopy which is not glued. This will help keep the canopy from cracking. I also trim the flange after it has been glued together with Zap-A-Dap-D-Goo down to 1/8th of an inch. You can paint the inside (before gluing) or the outside (after gluing). I wouldn't use the black outline decals. I paint that portion instead.
Follow the instructions.
The Tsurugi Web Site
Copyright © 1998 Chris Berardi. All rights reserved.
Revised: November 25, 1999.
