GrandRC
Heliman
Location: San Jose, California
| (Updating with new pictures and build for final production version of the Kasama Srimok head. Original build thread was based on a prototype)
Howdy all
Thought I would take a second and write up my overall experience with the brand new Kasama Srimok head for the Raptor 90. I have 3 Raptor 90's currently. All are identical with respect to power plant and electronics. Each runs an OS91SZ with OMI/Cline modified 60M carburetor, Hatori SB18L pipe, CSM 720 gyro, CSM RL10 Revlock and CSM CarbSmart. (For more info on the CarbSmart, see this thread: http://www.runryder.com/helicopter/t412562p1/)
Grand RC is my supplier of choice for all of the CSM gear, including the CarbSmart http://grandrc.com/goveners?start=15
2 of my R90's run the full Thunder Tiger SE head, bird cage, updated flybar to get the new mix ratio, infinavation dampers, and all the other goodies. These two fly very well. R90 #3 has a full Top Dragon head on it and for me it just never felt as good as the SE config. I was in Grand RC a month or so back and wound up spending a Saturday out at the flying field watching Ed and his son and a few of their friends tearing it up with a few nice TREX 600, a beautiful Synergy and an awesome Stratus. Both the Stratus and Synergy had all kinds of Kasama goodies. I was talking to Ed about potentially updating my #3 R90 to the new 903D config to get it as crisp and precise as my first 2. Ed mentioned that Kasama was releasing a new Srimok head for the R90 that would look essentially identical to the Kasama head on the Synergy I had been watching in awe... Since I already have 2 Raptor 50's running full Kasama heads, that part was an easy decision. And since my R50 Kasama heads and pretty much all of the CSM toys on all of my birds came from Grand, working with Ed and family was no question at all.
The head build is pretty straight forward, with only a few minor things to look out for.
Kasama has a very good illustrated parts break down available at: http://kasama.com/kasamafile/ASSEMB...RAPTOR%2090.pdf
So let's get started. Assume we are going to use Locktite Blue on every bolt.
The head arrives in 2 bags, with all parts sealed nicely.
   
The first thing I did was to assemble the grips. The grips are absolutely beautiful as far as machining, and have full radial and thrust bearings installed from the factory. When you assemble, notice items numbers 12 and 13 in the Kasama drawing. You need to be careful here as the two bolts for the grip arm have a different length. They will go in either way, but if you place the the long bolt in the hole closest to the blade bolt it will bottom out into the thrust bearing and kick the thrust bearing slightly out of alignment. Very easy to notice when you try to slide the spindle in and the thrust bearing binds up a little!
Next I installed the bell/hiller mixers on the end of the grip arm. The mixer comes pre-assembled. All there is to do is run in the stainless bolt. Every bolt that passes through a bearing is perfectly machined stainless, and has the correct length shoulder to remove the need for those pesky aluminum sleeves used on the TT parts.
This is the grip with the grip arm and mixer installed.
Next came the head block itself. This is a simple matter of assembling and installing the dampers. The dampers are very similar to Infinivation or other O-Ring style. 3 O-Rings slide over the damper support. The damper assembles with the larger flange on the damper support to the outside. I gave the dampers a shot of Tri-Flow and slid them into the head block.
 
Next piece is the flybar carrier. This is very simple. It slides into the head block, and is attached using two M3x7 bolts through the pre-installed bearings in the head block. Once the carrier is in place, you can add the ball links. Kasama calls these the "Srimok linkage double ball" (part number 23). These go on the inner holes, on the back side of the carrier with respect to head rotation.
The inner holes provide more flybar tilt for greater cyclic pitch.
The next piece to assemble is the flybar and flybar control arms. Slide the flybar into the carrier from the side facing you. The flybar control arms sit in the two slots cut in the carrier close to the head block. The control arms are to the rear with respect to rotation. This means the one closest to you will face to the right, and the far side to the left. Another way to make sure you have it right is the flybar control arms are on the same side as the linkage double ball we installed earlier.
The flybar is secured using two flybar collars (part number 25). Centering is pretty easy. The stock Raptor flybar has two machined flats used with the stock flybar arms. These flats will be partially exposed on each side of the flybar carrier. Center the bar visually using the amount of flat spot exposed on each side of the carrier. Slide one of the collars over and tighten the grub screw. Check that all is still centered well using the exposed flat on the remaining side. If it all looks good, slide the other collar in against the carrier and tighten the grub screw.
The next step is to align the control arms. The goal here is to have the control arm grub screws 180 degrees apart. This puts in the correct "droop" on the control arms to give maximum control throw on the flybar. This is actually quite simple. First tighten up one of the arms so the arm is centered side to side in the slot. It does not matter where on rotation you are, just get the arm centered in the slot so it does not rub on either side. (Don't forget the locktite!) Now we need to get the other arm aligned. With a hex driver in the tightened arm, align the hex driver in the arm you need to tighten so they are exactly parallel by eye. The picture shows it better than I can explain.
At this point you can install the grips and spindle in the head. This is essentially identical to a stock Raptor configuration with a 5mm bolt and washer at each end. Locktite the bolts when you assemble and tighten it up. You may feel a little drag against the dampers here as you move the grips, but as soon as you pull outward on the grips (centrifugal force), they are smooth as glass.
Moving forward, it is time to install the headblock onto he main shaft. Remove the old head assembly everything above the washout. Drop the new headblock onto the main shaft. Install and tighten the main head bolt (jesus bolt). Next add the two M3x18 lower pinch bolts (part number 31). These you want to snug back and forth so you get an even compression from both sides. Notice these bolts come in from opposite sides.
Now it is time to put the linkages together. The Kasama instruction sheet gives exact length of the 2 different control link sets. I used Fortune Model Products Ultra Link ends and the supplied link rods. Assemble your linkages to the correct length and size the link ends using your favorite methods. Install the links on the head as per the Kasama drawing.
Assemble your linkages to the correct length and size the link ends using your favorite methods. Install the links on the head as per the Kasama drawing. 
Ok, so now we have the head installed, and the control linkages setup. Time for basic radio setup. First we need to reverse the collective servo. The Kasama runs an opposite collective direction than the stock R90. Now when the swash goes up, collective goes positive. Reverse your collective and center your servo arm using sub trim. With the collective servo centered (center stick) and the swash level, adjust the collective rod length until you get the washout arms parallel. This is your baseline for collective adjustment. At this point the washout should be pretty much centered in it's travel range, and if you measure pitch you should be very close to zero degrees.
The flybar angle has a major effect on pitch measurement, so make sure you get it perpendicular to the shaft. For precise zero on pitch, I use a 11/32 drill bit between the top of the flybar carrier and the head block. This lets me lock the flybar level and get both blades zeroed exactly when measured over the boom. Done properly, you won't have a hint or tracking issues.
The last thing to complete on install is paddle alignment. With zero pitch and a level swash, paddle alignment is easy. I use a Robbe paddle alignment set. With zero pitch all around, the paddles should be directly in alignment with each other, as well as the exactly parallel to the main blades. In this picture, I would align the top of the paddle gauge to the dead center of my SAB blades.
This thing is one beautiful piece of machinery!
Depending on linkage setup, the Kasama head is capable of +15/-15 degrees of pitch!!! Using the outer holes on the mixer gives a monster pitch range. I am currently using the inner hole on the grip side, along with inner of the dual ball setup. This gives me an easy +12/-12 with plenty of swash travel left. 
After a test flight today, I will move to the outer hole on the mixer to see what is possible!!
Finally my chief quality control inspector had to give the new bird a final QC stamp of approval. My grandson Bly thinks Raptors are way cool, and Kasama is "whoa" 
The Kasama Srimok head for the R90 is in stock at Grand RC! http://grandrc.com/inc/sdetail/128609 |
, what is the weigh of complet kasama head??
Dude, that's two directions!
