Raptor .90 SE
First one should know what the difference is when comparing the Raptor .90 SE to the Raptor .90 std. The SE is basically a fully up-graded Raptor .90. Included in the kit is a full metal head (with the exception of mixer arms), metal upper and lower mast bearing blocks, carbon fiber upper and lower frames, carbon fiber/metal collective arm, a carbon fiber tail boom, carbon fiber fins, carbon fiber rear mount for tail rotor servo, carbon fiber tail boom supports with metal ends, metal tail boom support/fin clamp, a metal fan and a metal tail pitch fork. In addition the carbon fiber sideframes have metal reinforcing doublers in the vicinity of the engine mount.
One might ask why the model doesn’t fly exactly as they like well right out of the box, after all it’s an SE. I have yet to see a perfect model helicopter, so if you want the best performance out of this (along with any other model) you will need to do some minor tweaking. I have had one issue with boom support bolts shearing off and on one occasion sending the bolt through the rotor blades while inverted. The fix for this is to file the boom support end fittings at the sideframe on an angle to relieve stress. A boom support bridge is also a good idea. This small inexpensive up-grade distributes the load from one boom support to the other minimizing fatigue on the bolts. This combined with the angled sideframe attachment fitting area has solved the problem for us.
I also suggest using green loc-tite (sleeve retainer) on all sleeves supporting any part of the control system and rotor head, this gets rid of any possible slop in the model. You can also file the sleeves to create a better overall fit if you’re a perfectionist. This is a good practice to follow on all of your models as it makes for a much tighter system. Also use caution when building the tail rotor grip and hub assembly. Use blue loc-tite on the new type longer grub screws and tighten them down into the grooves on the shaft with moderate force. DO NOT over tighten the nuts!! The new grub screws now included in all kits are 19mm in length and be sure not to use ones less than this length. When you feel the nut hit the hub go just a tad further and then stop. Over tightening these nuts will stress the grub screws causing a failure. Over tightening the grub screw will stress the aluminum hub. If you work the machine really hard in flight and find that the hub gets a tiny bit loose on the gearbox output shaft from time to time it can be bonded with sleeve retainer. When securing the gear pin (BK0414 | 2×12 pin) in the tail rotor gear box make sure not to apply too much torque. Use some blue loc-tite and again, apply moderate force on the screw, you don’t need to come down on these really hard and bend them but you don’t want them too loose either. These pins can use loctite sleeve retainer to add holding security to the shaft. The one way auto hub also comes with grease in it for preservation purposes, this needs to be cleaned out with a solvent and the bearing should be lubed with a light oil. These bigger helis are not meant for beginners, an experienced builder will have no problem with this model. The above is just a reminder. If this model is built properly there are no major problems. While fits are of a high quality a DTI should be used to at least check fan and clutch runout.
Now that you’re confident that the model is assembled correctly go break the engine in
Out of the box this model is not setup for wild 3D, it’s more of an FAI/F3C helicopter. The model proved to be very stable and smooth from the box to the flight line. All links were measured prior to flying and no tracking adjustment was needed. After running 3 or 4 tanks through the TT.90 I was confident that it would not quit or do anything strange in flight. 3 tanks of hovering and FF gets boring pretty quick so up I took it for some mild 3D. It did just that, very mild 3D and FAI with the stock paddles. I added throttle to cyclic and tail rotor mixing and engaged a new device from Model Avionics called an RPM limiter. It’s sort of like a governor but better in having no lag in response time. The model flew better like this but the cyclic is still a bit slow. I slapped some white MA 20g paddles on the machine and it became better, but still not what I was hoping for. While the 95mm V-paddles normally give exceptional performance and are an improvement over the MA20g units, it was still not up to my expectations powering 710mm 190 gram carbom blades. With 710mm blades and the wide blade bolt spacing we end up with a rather massive and stable rotor disk.
A flybar ratio change was next on the agenda. The stock flybar ratio is 1:1. Our modified mixers offer a 0.75 ratio when moved into the inner hole on the flybar carrier. This means that for every one degree of flybar tilt the blades tilt ¾ of a degree. This also gives a broader collective and cyclic pitch range allowing for about -/+7.5 degrees of cyclic pitch (with no binding in the corners) and better than -12/+12 degrees of collective pitch (stock is -11/+11). This small modification is necessary for 3D when using longer, heavier blades because as you know the raptor head is wider than most. The extra collective range is not needed, but is rather a result of acquiring larger cyclic blade angles. It does however, add pop. The stock mixers must be cut shorter on the longer end and a new hole needs to be drilled. This is what offers a larger cyclic pitch range. The stock arms will not fit the inner hole as they also hit the bolts securing the flybar carrier so some grinding must be done to the stepped part on the inside of the mixer. Grind it down just enough to clear the bolts or use pan head bolts at the carrier teeter bearings.
I also think anyone with a .90 size engine should treat themselves to a Muscle Pipe-II. This tuned muffler/pipe works very well. It’s quiet, runs smooth, puts out good power and does not cause the engine to hang up in autos. One cannot acquire all that in a tuned pipe or a regular muffler!
All in all the raptor .90 SE does not need very much TLC, a bit of caution when building and a few simple mods really make this model come to life! In my opinion it’s a well made heli and with the above modifications it has met my expectations.