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Old 01-12-2013, 01:26 PM   #1 (permalink)
rdlohr
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Join Date: May 2006
Default Ricks Rush 750 build thread

Finally started my build. Figured I would start a thread to keep track of my questions, answers, notes, tips and such. I also plan to mark up my owners manual and make it available.

First observation. The nicely machined parts all came separately packaged with associated hardware separated in 2 squares of foam with slots cut out for each. I like that because it protects the parts and keeps them in place for me while I build.


The only nit improvement I could think of would be to individually mark each slot or bag and reference them from the manual so that you don't have to pull parts out to see if they are what you need.

Assembly 1 Flybarless Head:
The manual calls out an M3 x 10 screw for the Head Button. It seems to bottom out early, but it is the correct length, so apply a lot of pressure to get it completely seated. (Edited)

The manual calls out Gray or White Dampers but I was provided Gray and Black. I assumed the Black replaced the White as medium stiffness and used them.

TIP: There was a note to install the pinch screws first. They have to be installed first since they can't be put in once the Radius Arms are installed. I would recommend doing page 2 first which installs the main shaft (including these screws) prior to doing page 1. That way you can loctite the screws prior to installing them (as normal) rather than have to slip in the loctite after the fact.

This is the first time I have ever used Red Loctite for screws that might need removal in a crash so I am a bit worried that they will be hard to remove. I'm sure the designers had good reason so I did it.

Assembly 2: Flybarless Head:

TIP: Clean the screws M6x16 screws and feathering shaft threads with alcohol to remove the machining oil. I guess this is standard practice but especially important here.

NOTE: The Damper Spacer and Thrust Washer are brass.


So far, so good. I love that the Radius arms attach to the head rather than having to attach them to a movable sleeve that has to be placed properly! I assume that allowed them to simplify the design and only require the upper grips to be adjustable.



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Assembly 2 Flybarless Head (Continued) Swash Plate:
Swash was pre-assembled. I removed each screw one by one to loctite, but I didn't disassemble it.

For the upper swash balls, only two were called for but I put in all four.

Nice touch that you can rebuild the swash plate.

Assembly 3 Frame Systems:
The flat washers came in a different bag with other stuff.

The pinion and set screws shown on this page are in Main Bag 7 with the Main Gear.
I didn't install the motor yet since I like to know which direction the wires on the motor should go for the cleanest install.

Assembly 3,4,5 Frame Systems (Continued):
Sliding motor mount with shaft support. Awesome!

I found the picture very difficult to use for mounting the components. Look at the next page to see where the components should go then come back.

The break away CF canopy mounts are another nice touch. The larger hole was milled a bit small so just ream them out with a rat tail file till Center Washer fits.

NOTE: Look now for the screws each canopy mount is installed on because they are not dedicated to the mount. Frame screws also hold the canopy mounts. I say this because I had to take two screws back out to install the canopy mounts on them.

TIP: I recommend building all four breakaway canopy mounts at once now so they will be ready to be install as you build the frame.

Assembly 4,5 Frame Systems (Continued):

NOTE: The Tray M3 Spacers are about .4" long and they are threaded inside. The Tray standoffs are about .65" long and they are not threaded inside.

NOTE: The longer 28 mm screws go through the Frame Doubler along the bottom, the shorter 25mm screws go on top. Don't mix them up. Only 4 Center Washers are used, not 6 because the Landing Gear mounts don't require them.

TIP: When installing the front canopy mounts, use the Frame Doubler to line them up.


Assembly 5,9 "A" Arm and Bell Cranks:

NOTE: The cylindrical Spacer 90 that comes in one of these bags will be used later when the Bell Cranks are mounted (Assembly 9).

Assembly 6 Boom Mount Assembly:
NOTE: Two of the Button Head Screws M3 X 6mm had to come from an unrelated bag.
NOTE: The Ball Bearing 12 X 18 x 4mm shown between the Boom Mount Rear and the Boom Mount Front was not only not in this bag, but I'm not sure it belongs there at all. I guess I will find out later. I would like to know if that bearing really goes in the boom mount.

Update: It does, but it is preinstalled and it is toward the back flush with the center part. Based on the manual drawing I was expecting a separate bearing that slipped right in front. That was a wrong assumption.


Assembly 6 Frame Assembly:
No comments.

Assembly 4 Frame Assembly (Continued):
No comments.

Assembly 4,5 Frame Systems(Continued):
The Servo Mounts that tack in place with the small Phillips Special Screws are a nice touch!

Assembly 3,4,5 Frame Systems(Continued 2 pages):
No comments.

Assembly 9 Bell Cranks:
Watch Scott's vid prior to doing the bell cranks:
http://www.youtube.com/watch?feature...&v=hJlv-i1XSy0

Assembly 8 Landing Gear Assembly:
I considered using nylon screws in place of the 4) M3x8x1 screws to allow the landing gear to break away in a crash, but with a heli this big, I decided to use the stock screws.

NOTE: I CAed the Landing strut tube caps in place.


Having completed the frame, I have to say it is a well thought out design and very sturdy. The battery tray area is different than any heli I have ever built and I look forward to seeing how it works out. Other than minor problems finding parts in different bags and hidden in the little slots, I'm very happy with the build so far.

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I'm skipping Assembly 5,9 Servo Installation for now. *I will do it later when I install all the electrical components.

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Assembly 7 Drive Gear:
This Main Gear is awesome. *The OWB spins more freely than any I have ever had.

Head Installation:
First heli I have had with 3 main shaft bearings. *I have to say that just seems like good design practice, especially with a heli this size.

The collarless design is a nice touch. *If you are going to have a third bearing, why not make it adjustable and not require a collar. *Cool. *Everything spins smooth as silk.




This is the first 90 size heli I have built so I don't know what the other main stream designs are doing, but I have to say that the designers seemed to go out of their way here to add value. *Lots of "Nice Touches". *


On the down side, the head linkages/grips/swash are not quite as smooth as I would like. *Hopefully they will free up a little with usage.

Edit: Watch this video on head tightness:
http://www.youtube.com/watch?feature...&v=DWSKk9YOYRc


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Assembly 10 Tail System:
I removed, cleaned and loctited all the screws.
The tail is sturdy and smooth.

Assembly 11 Tail System (Continued)
Watch Scott's video first:
http://www.youtube.com/watch?feature...&v=GB3EeRSROZA

The slider arm went together easily and it is very sturdy.

I notice the pin screws contact the black plastic groove on the slider assembly snugly and cause it to not slide as smoothly as it could. Is this OK as is or should it be lubricated with something?
Edit: I sanded down the pins a bit, and added a little Tri-Flow Oil. I kept at it until the the blades drop under their own weight like Scott's video shows.


Assembly 11 Tail System (Continued)
Nice sturdy design using screws instead of links and balls.

Assembly 12 Tail Linkage Rod
No comments.

Assembly 12 Torque Tube Shaft 2 pages
22 mm equals .866"
250 mm equals about 9"

When you put the rubber doughnuts on the bearings, when they are fully seated, the rubber comes down over the bearing and it should look evenly seated on both sides of the bearing. Sometimes the rubber gets stuck up on the edge of the bearing and does not come down the whole way. Keep working it and it will come down.

There are two main options here:
Option 1) CA the bearings to the TT as the manual shows. Use an exacto knife to score a line the whole way around under each bearing to give the CA something to grab on. Make sure the CA is completely cured prior to pushing the assembly into the boom. Be careful because I hadn't fully scored each bearing and one came loose as I pushed it in.

Option 2) Use the clear plastic tube that came with the kit to slide the bearings/doughnuts into the tube. Mark the tube with a sharpie at the correct depth to push in them in. Then slide the TT through the bearings. (I didn't try this, but I may next time)

Assembly 12 Tail Rod and Guides
I spaced my guides 200 mm apart starting about 27 mm from the boom block.

Assembly 4,10 & 11 Tail Systems (Continued)
I was unable to screw down the pin screw once my Tail Fin was installed, so I used a rat tail file to file the inside of the U to just bigger than the pin screw head.

I then was able to install the cap screws snug and turn the tail to be parallel with the frame of the heli. I used my digital pitch gauge to make them parallel. Then I installed the pin screw. I then tightened down the cap screws. (with loctite on them)

Assembly 12 Tail Systems (Continued)
Install the large cap screws using Red 271 or Green 290 loctite. Do not use Blue 242 because people have had problems with these coming loose.

Assembly 2,11 Rotor Blades
I used the thickest spacers with my Curtis Youngblood blades. I placed the spacers on top the blades.

Swash Leveling and Main Blade Zero Pitch
This part is just unbelievably cool.

I installed the two provided zero pitch rods to hold the Bell Cranks and Elevator Assembly at a perfect 90, then made up the linkage rods with 28 mm between heads like the Head Installation page showed.

I installed my Underswash Leveling Tool just under the swash at the height dictated by the Elevator link. I turned it a few times to allow it to level itself then I turned the main shaft a few turns to make sure it was level. Finally I lined up my swash level with the tool.



I then put my links up against the balls to determine how much I need to adjust them, and they were BOTH exactly right. The swash was perfectly level using the lengths called out by the manual. NO WAY. They were just right.

Next, I pulled my blades to the side to see if they matched and they also were right on. I used my digital pitch gauge to compare the pitch at zero to the boom and they were right on. NO WAY. That was just way too cool!

I realize that I had been a bit lucky and any of the links could have been off by a turn or so but I am just amazed at how nicely designed this is!


All the links are quite tight on the balls. Scott says they wear in after a few flights so I won't size them.


Hope these posts help someone.
Rick
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Last edited by rdlohr; 01-23-2013 at 08:51 PM..
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