2-Blades Flybarless T-Rex Experimental

[Super-Hornet]

Information:
This is an experimental. I don't mind sharing the design if anyone interested.

Day 1 (Mar 08, 2005)
--------------------
Feeling bored so decided to do some experimental on my T-Rex. Purchase some parts for the T-Rex Rotor Head.
Design version #1 2-Blades Flybarless Rotor Head. Found out the Stock Plastic Bushing at the feathering shaft is the same diameter as brass bushing used in main blades. So, replace the stock plastic bushing using brass bushing.

Setting: 28% for Aileron and Elevator in Swash AFR setting. Dual Rate 100% & Exponential of 35%.

Tested: Hovering in 2.5m x 2.5m open space in living room ok.. Confident to hover. Much Much better than my previous Hornet 2 Flybarless (Which I mod it myself). Bring out to Yishun Ave 9 open field to fly (Night time) but not good in forward flight. OK in hover but when u start to move, it roll to any direction. Tried different AFR and Expo but still don't like it. Decided to replace back my flybar type head later on when reach home.

[Super-Hornet]

Day 2 (Mar 08, 2005)
---------------------
Really like the look of flybarless head so decided to try again. I feel that the reason the heli not stable is because it lack of Gyroscopic effect. Since T-Rex are using feathering shaft type, it act like a real heli teeter (Or See-Saw at the center of the hub). Then decided to play around with the feathering shaft to mimic the real heli teeter. Tried using softer O ring to create softer damping effect. Result Not good. Worse then yesterday in Hovering mode. Then try using back stock O ring but with extra washer to make the damping effect higher (Stronger).

Tested: Hovering in 2.5m x 2.5m open space in living room are much better than yesterday nite. Bring to Ave 9 again but tonite got a lot of people playing soccer, so very limited airspace. Open space hovering and a bit of forward flight much better. I can now use higher Swash AFR setting (More cyclics throw).

Current Settings: 42% in Aileron and Elevator. 33% in Expo. 100% in Dual Rate.

[Super-Hornet]

{ Day #3 Mar 9, 2005 and More pictures coming soon }

[Super-Hornet]

2-Blades Flybarless Head:
All parts are actually from T-Rex Original parts or spare parts.

Swash to Blades linkage (Pitch/Cyclics).
--------------------------------------
Notice that I use the mechanical linkage for 2 reasons:
1 - To reduce/or having higher resolution movement for the cyclics/pitch
2 - To increase the servo strenght (Trade big movement to small movement and u gain strenght)

[Super-Hornet]

Inner Swash Plate AntiRotation Lock
-----------------------------------
Again.. from trex spare/stock parts.

This is to prevent the inner swash plate from turning when applying cyclics/pitch.

[Super-Hornet]

Here is my T-Rex Flybar-Paddles Head. If I anytime decided not to go flybarless, I can just swap back to this head.

[Super-Hornet]

Day 3 (Mar 9, 2005)
Modify the inner swash plate anti-rotation linkage to a shorter version. Other than that, no changes in mechanical. Tried different AFR value and Expo. So far so good. Still... don't have the chance to test forward flight. I went downstair void deck to test hover and with some wind condition. Only hover and a small forward movement in void deck. Also, complete hovering in my living room for 1 pack of battery.

Result so far: The cyclics is really faster than before.. Like instantaneous or no lag. Cyclics can be as fast as stock configuration or higher....depend your choices. Hover wise, it is close or the same as with paddles. Flight characteristic slightly different from paddles but still can handle it. More sensitive to wind as compare to previous but that could be due to lighter weight now. (No paddles, flybar see-saw and flybar). I would like to do more testing on it.

Just before I took the above pictures, I try hover in my living room again with this time using Stock Wooden Blades (315mm). Heck!! I works! Some of u might notice that if using Carbon blades, the cyclics is slower than using wooden blades. It is true in this case also. Finish hovering for 1 full pack the flight time is around 12+ minutes. Using this wooden blades, I can really hear that the headspeed is very fast!

Things intend to do/try if got time and mood:
1 - Individual Blade flapping hinge.
2 - Semi Flybarless (Or using Stabilizer Arm) like UH-1 Huey
3 - 4 Blades?

Super-Hornet

[X34]

SH,

Really respect u for your effort. I know your fly bar is missing, u can make it more stable if u can add or install your washout lever at the pitch arm. Helps in the cyclic.

[Super-Hornet]

Hi James... Can u elaborate a bit more on washout? Are u refering to "swash to washout to blade grips"? If so, then doing so is actually amplified the cyclics movement. Cyclics will become too sensitive and weak. If u refering to "swash to washout to mixer to blade grip", then it maybe possible. I can try but I suspect it may have problem when u increase pitch. (Cyclics is ok but pitch may have problem)

Super-Hornet

[X34]

Hi SH,

Right now with your setup, your cyclic transition is very sudden, if u add an equal mixer on the blade grip arm, both ends of the mixer connects to the swash, u get smoother transition or less sensitive.

Make sense 2 u?

James

[Super-Hornet]

Sounds interesting but I still can't visualize your design. Can u show me a rough schetch?

Thanks

Super-Hornet

[X34]

Sounds interesting but I still can't visualize your design. Can u show me a rough schetch?

Thanks

Super-Hornet

Sketch file too big cannot attach. can email 2 u, pm your email add.

[Super-Hornet]

PM u my email liau.

[X34]

u got mail

[Super-Hornet]

Thanks James.

This is what u email to me...