Why is tail rotor on right side of T-Rex?

[PilotSmith]

I ordered a MD500E body for my T-Rex 450. I noticed that the real helis have the tail rotor on the left side. The T-Rex has it on the right side. Does it make any difference what side the tail rotor is on? I'm putting the body on just for fun so I doubt I will swap the direction of the tail unless it is an easy modification. Curious if it makes any difference in flight characteristics if you swap it around? Seems like it would make no difference.

[saltyzoo]

I ordered a MD500E body for my T-Rex 450. I noticed that the real helis have the tail rotor on the left side. The T-Rex has it on the right side. Does it make any difference what side the tail rotor is on? I'm putting the body on just for fun so I doubt I will swap the direction of the tail unless it is an easy modification. Curious if it makes any difference in flight characteristics if you swap it around? Seems like it would make no difference.
Ideally you want the tail rotor to turn up into the downwash from the main rotors so that they don't lose effectiveness by traveling "with" the downwash. It's not a simple change, though I don't have time to go into all the details of pusher vs tractor tail rotors and clockwise vs CCW main rotors. If someone else doesn't do it later today I'll have time. ;)

[saltyzoo]

Ok, more info that you wanted to know coming up. ;)

The trex (450 at least) uses a pusher tail rotor that rotates up into the main rotor wash. If you moved the rotor to the other side of the boom you would be making it a tractor.

Pusher meaning that it pushes the tail boom, while a tractor "pulls" the tail boom.

Tractor tail rotors are typically less efficient due to the boom and vertical fin obstructing airflow.

Also, if you switched sides on the trex you would be rotating the tail rotor down with the main rotor wash, which would further compromise it's efficiency. Though the Trex boom is arguably long enough to keep the tail rotor out of the wash anyway, in forward flight it could be an issue as the main rotor wash would be blown back toward the tail rotor.

All in all, it's not as simple as just flipping it around, and unless you are really serious about scale, it's probably not worth the effort and or risk of reducing your tail response.

I have to give footnote credit to an ancient tomb I read years ago, written by Ray Hostetler. Not sure if this guy is even still around the hobby anymore. "Ray's Complete Helicopter Manual" 3rd Edition, 1991.

Hope there was something useful in this post.

[Rodan]

All in all, it's not as simple as just flipping it around, and unless you are really serious about scale, it's probably not worth the effort and or risk of reducing your tail response.


Atually, it is very simple to flip the T/R...

All of the above regarding tractor/pusher tail rotors is correct, and it is possible to suffer some loss of tail authority when you flip it. The Align EC-135 is a perfect example because the vertical stab blocks most of the t/r. The main reason most r/c helis' T/Rs are on the starboard side is due to the right hand rotation of the main rotor, allowing them to rotate up, into the downwash as saltyzoo noted, and be a pusher for max efficiency. This is a requirement for hard 3D.

On a scale ship, you don't need the absolute authority to counter 14 deg of collective pitch, so you can get away with a little more. 'Flipping' the T/R entails rotating the entire tail case on the boom (and the servo), and twisting the belt the other way to maintain a rotation up into the downwash. You will then have to flip the tail blade holders to maintain the pitch control on the leading edge. Check everything and make any necessary reversals in the gyro or TX to get it all working right.

On my MD500E Raptor, after doing the above, I didn't even have to make any changes in the servo or gyro directions, and it flies like a champ. I'm doing the same with a 60 size JetRanger based on stretched TRex600E mechs, except it's TT drive, but the main rotor has been converted to left hand rotation (correct for scale), so the tail rotates in the proper direction. It's also flybarless...;)

Don't be afraid to flip the T/R, it's really not that big a deal, and really makes a difference in the appearance of a scaler.

[Wyldman]

OK, I'm wondering, if flipped to the port side, why can't you just also flip the belt on the drive pulley in the frame and then just turn over the blades in the grips?

Wouldn't this still give an upward rotation into the rotor wash, providing the same control as the opposite setup on the starboard side?

You might have to reverse your tail servo direction in the radio, but would this work?

[Super-Hornet]

Like what Rodan said, flipping to the other side is easy. When u flip over to the other side, the rotor spin downward. If u want it to spin upward, u flip the belt as well and all the tail linkages and tail blade grips need to flip over as well. For tail rotor, having trailing edge controlling don't seems to effect anything (that is what I experiences). What u need is to make sure both side of the rotor pitch (+ve and -ve tail rotor pitch) has enough travel.

I have TRex450 of:
MD500E, Main rotor = CCW, Tail on the left, spin downward.
A109, Main rotor = CCW, Tail on the left, spin upward.
UH-1C, Main rotor = CCW, Tail on the left, spin upward.
Schweizer 300C (in the process of building), Main rotor = CCW, Tail on the left, spin downward.

and Mini-Titan of:
AH-1W, Main rotor = CCW, Tail on the right, spin upward.

All this is for scale purposes.

SH

[PilotSmith]

Ok, thanks for the info! Sounds simple enough. Should have the 500E fuselage by tomorrow. Once it arrives I will decide what to do. If I don't have to modify the fuselage, and it is just a matter of rotating the boom, twisting the belt in the other direction, and reversing the tail blades, it sounds like a 15 - 30 minute job.

I saw the MD500E fuselage today at the LHS. Man, that thing is BIG.

I didn't even think it was a T-Rex 450 fuselage when I first saw it. I thought it was some larger heli. Only after taking the nose off to look inside did I realize it was a 450. I can sure use the extra size. The 450 gets small in the sky pretty quick during FFF.

[Mr-C]

I think the tails on these helis are so powerful that you can pretty much do whatever you want within reason. Only the extreme pilots need to worry.

[PilotSmith]

After I did the mod to the tail (added counterweights to the blade grips) it has plenty of power to react to even the dumbest of things I can come up with. Since I won't be doing anything more than some occasional flips, rolls and loops, I don't think I need nearly the power the tail currently has.