Pre-production Twinn-Rexx build pictures

[sokal]

yes
iv just put the 401 and thr 3400g in and trying to understand it
i fly the blade 400 the cheaper trex but have all the same servos and gyro as one
im doing ok can do trafic circles hover (not to well nose in) but otherwise im zipping all over. just need to get a handle on this tail thing
if you have answers my ears are open im going to rebind been told thats a thing to do. well thanks

[Gra55h0pper]

Sokal - sounds to me that given you're experience with the blade 400 you'd pretty much ready for the Twinn-Rexx! One thing you could do is get a regular Trex first, and then when you get the Twinn-Rexx, use the complete rotor-head, gyro, speed controller, servos, etc. as a starting point for it...

What's the problem you've been having with the tail on the blade 400?

[Gra55h0pper]

My three bladed heads have come in (see pic)...
In general, looks pretty good! The machining of the swash and blade holders seems nice. One thing I don't like though is the linkage balls (they don't seem as smooth as the ones I have on the Twinn-Rexx) and the linkages themselves. I think I'm going to swap these out for Align ones. That's an easy job though.

Too many plans, too little time! Guess I'll finish the fuselage first before starting to fiddle around with these...

Any recommendations which blades would be best to use with these heads?

[chinookmark]

Awesome! I can't wait to hear how they fly! I'd start with 325's (or whatever you're already using) and go from there. There's a bunch of good information about multi-blade heads on Scalerchelis.com. Super Hornet has a lot of experience with T-rex size multis.

Is there any articulation or damping in the heads? How about crash repairability ... are the feathering shafts easy to replace? What's the radius from center to blade pivot? Where is the blade height in relation to stock T-rex?

I've got my own design hub being machined this weekend. It's the first prototype after the balsa mockup. I only had one made, since I'm betting it's not going to work -- I just need to find out why, and then work on ver.2. If it works, two heads will cost me about $100 worth of oem Trex parts plus hubs and swashplates.

[sokal]

well i tor the crap they put on it off and got real servos and gyro
not used to the speed of them but i seem to have the tail installed right i guess
it holds in a hover but what seem funny to my is say i add a right yaw movement
when i center up it seem not to stop dead but like a spring back action
its been 1.5 weeks since i was able to fly her due to the crapy tail servo it came with (burnt out) that is why the new gyro and servo.

[sokal]

still wondering why fully articulating rotor heads arent used in rc

[v22chap]

grass hopper
Yep the blades are on right ,,but have done worse than that before ..... one on right and the other backwards .,,not on a rex but a larger bird with no markings on the blades ...that really causes a problem

Sokal

Love the V pix ,,,was that pax river or new river ,,, I have been to pax and meet the guys down there ...what a great group ,,,and what a neat bird . Hope I can get mine going again soon .

[sokal]

v22chap,
not sure its the one in North Carolina had to been atlease several 100 of them

[v22chap]

Sokal
And they all look alike too ,,It don't quite look like the one I was to ,,,but that has been 5 yrs ago and I wasn't looking at the building at all
Thanks for more pix

[Gra55h0pper]

Finally, made a video... I realized my wife has a digital camera with the capability to make short video clips. I wasn't able to show forward flight at this point as it's taken in my backyard next to the swimming-pool... Wind was moderate. It shows: stable hover, pitch changes, yaw control and some "messing around"

RC Tandem Chinook Helicopter - Twinn Rexx (1 min 27 sec)

[v22chap]

Cool Grass hopper
That baby is really reved up .... ever put one in your pool ??

[chinookmark]

That sounds awesome! You're blades make a really cool sound. What pinion/headspeed are you running?

[Gra55h0pper]

Yeah, it sounds pretty cool in the video. I need to check the head speed, but I don't think I have it up that high. I think it's more the sound bouncing off the walls of the house. As my wife made the video she was standing in the sliding glass door opening which may have distorted the sound somewhat.

[v22chap]

Ya ,,like the one I did in the garage ...

[Gra55h0pper]

We're getting there! I finished applying the decals (except for a Grasshopper which I still plan to put on the tail) and did another test-fit. See pictures!

[v22chap]

looks really good grass hopper

[MadDogDan]

h0pper,

I don't have my fuselage yet but will soon and was thinking about leaving the windows clear. Are the windows well defined? If they are, I was thinking of masking them off so they would be clear when I remove the tape after painting. Did you use the flybar limiter in the back? I have blow up the pictures in the video manual to 400% but still can't figure out how it is rigged up.

MadDog

[chinookmark]

MadDog,
The cockpit windows are well-difined, and are the round windows on the cabin door (not shown on Gra55h0pper's bird). The rest aren't molded, so you can easily do either airline style or military style.

[Gra55h0pper]

Originally Posted by MadDogDan

I don't have my fuselage yet but will soon and was thinking about leaving the windows clear

MadDog -- Only the cockpit windows and the round window in the door behind the cockpit are "defined". See: http://www.tech-mp.com/Twinn_Rexx/TRB1.jpg. I was happy about that as it made it easier to create a version with "civilian" windows. I used liquid masking film, "scribing" with an X-acto knife around a window template I created from a piece of spare body plastic. It worked out great but the whole procedure is a bit of a pain as you need to mask the windows before you can sand and prime the body which means you need to carefully sand around and in-between the windows. Also, as the liquid masking film is soluable in water, I couldn't just wash the whole fuse with water and soap in order to degrease it which I only realized after applying the masking film.

Given my learnings, I'd recommend the following "window procedure":
- after prep, wash the whole fuse with water and soap
- from this point on: wear gloves when handling the body (or at least: wash you're hands "all the time")
- apply liquid masking film
- scribe around the window template
- remove the liquid masking film around the windows
- sand the body staying away from the windows
- use a rag to remove any dust
- prime -> sand -> paint -> apply decals -> apply clear coat

The result looks great but it's a bit of work. The alternative (much less work) would be to simply apply the windows as printed decals.

Note that I used transparent black window paint on the inside of the windows which -in hindsight- I probably wouldn't do again as it made the windows a little too dark. Then again, I haven't looked at it in bright sunlight yet.

Can you post pictures of your progress?

[MadDogDan]

hopper,

I am not even finished with my build yet, in fact my TH2 mixer just came in today. I have done quite a bit of automotive painting and I was thinking of using auto grade masking tape and an Xacto to mask and trim the windows. For the porthole windows I was going to use circular price stickers in the proper diameter. They would then be pulled off when the paint dries. To reduce weight, I was going to use a lacquer that doesn't require primer or a clear coat. I am going to paint mine like the NASA helo and have Callie from "Callie Graphics" do all of the dry transfer decals. On another note: After looking at this mixer board, I am going to have to call Joe on Monday to get through the physical hook up of this thing.

MadDog