How do I tame the T-Rex 450?

For questions regarding the models and airports / Bei Fragen zu Modellen und Airports
Post Reply
dmulligan
Posts: 20
Joined: 20 Mar 2009 01:30

How do I tame the T-Rex 450?

Post by dmulligan »

My personal HK450, an align v1 clone, is very very tame. I've got a 200mm flybar, weights on the flybar, a 2400rpm headspeed, slow cyclic servos and 30% expo programmed into my DX7. All of this makes my 450 very very tame and stable to fly.

I took the T-Rex 450 that came with Heli-X, called "TRex," and adjusted the following:
RotorRevPerMin100 = 2400
NickExpo = 30
RollExpo = 30
MassPaddle = 0.030
LengthFlybar = 0.20

After all of these changes it is closer to mine but it is still very twitchy in comparison. By twitchy I mean that the cyclic controls are still sensitive and fast. What is the best way to tame the model further?

Thanks,
David
dmulligan
Posts: 20
Joined: 20 Mar 2009 01:30

Re: How do I tame the T-Rex 450?

Post by dmulligan »

I moved the headspeed up to 2600 rpm. This helped to stabilize the heli some and it is closer to my real heli other than my real heli has a max headspeed of 2400 rpm. The cyclic speed is still a too fast, now the throttle is just more stable.
User avatar
Michael
Posts: 1825
Joined: 25 May 2008 16:11
Location: Germany
Contact:

Re: How do I tame the T-Rex 450?

Post by Michael »

Hello David,

you have several options:

1. Increase the mass of the fly bar further
2. Decrease the area of the paddles
3. Decrease the min/max degrees of the paddles and the blades
4. Use the expo settings
5 Decrease the PaddlePitchFactor (This defines how much a roll of the paddles transfer to the baldes)

Hope that helps.

Michael
dmulligan
Posts: 20
Joined: 20 Mar 2009 01:30

Re: How do I tame the T-Rex 450?

Post by dmulligan »

I will try some of those when I get home. I've discovered that my paddle mass should be closer to 5g which would make a big difference I would think.

Is MassFlybar the mass of the flybar rod itself or the weights on the flybar? Or do they amount to the same thing?

Thanks again,
David
User avatar
Michael
Posts: 1825
Joined: 25 May 2008 16:11
Location: Germany
Contact:

Re: How do I tame the T-Rex 450?

Post by Michael »

MassFlybar is the mass of the bar itself. And I forgot, you can also change the mass of the paddle.

And please note: all units are SI units, i.e. m, kg

Michael
dmulligan
Posts: 20
Joined: 20 Mar 2009 01:30

Re: How do I tame the T-Rex 450?

Post by dmulligan »

Yes I've been using the MassPaddle already, I just underestimated the mass of the paddles and weights that I have on my real model.

Thanks,
David
dmulligan
Posts: 20
Joined: 20 Mar 2009 01:30

Re: How do I tame the T-Rex 450?

Post by dmulligan »

Increasing the MassPaddle parameter to 0.060 did the trick. The heli still doesn't feel quite right but it is significantly better now.

For one thing, it lands way too easily. My real helicopter bounces and/or threatens to tip over if I do not set it down gently. Also the helicopter seems to be too small or perhaps it shrinks too quickly as I fly away. Not sure. It just doesn't seem to look as big as my own.

For the rest I need to tweak some more settings and fly my real model to compare. If I feel motivated perhaps I will publish my results as a new heli.
User avatar
Michael
Posts: 1825
Joined: 25 May 2008 16:11
Location: Germany
Contact:

Re: How do I tame the T-Rex 450?

Post by Michael »

dmulligan wrote: For one thing, it lands way too easily. My real helicopter bounces and/or threatens to tip over if I do not set it down gently.
For this, they are parameters which define the stiffness and the viscosity while hitting the ground. However, the collision part of HELI-X has completely changed in version 2.0. Thus I would wait, before putting to much effort in this part.
dmulligan wrote: Also the helicopter seems to be too small or perhaps it shrinks too quickly as I fly away. Not sure. It just doesn't seem to look as big as my own.
In HELI-X, the physics is completely decoupled from the appearance of the model. So you can increase the model by changing
<SizeOfScaleDeterminantPart> while the pysics is unchanged.

Have fun,

Michael
dmulligan
Posts: 20
Joined: 20 Mar 2009 01:30

Re: How do I tame the T-Rex 450?

Post by dmulligan »

Thank you for your help Michael. I got some side in hover practicing last week using Heli-X before heading to the gym with my local heli club. While side in hovering my real 450 model I started drifting forward by accident and let it continue as I had the room. I then turned around and flew forward on purpose. I might have done that 6 to 8 times! This was the first time I've gone past just hovering side in. I could not have done that without the practice I got with Heli-x.

After some consideration I don't think that the model is that much smaller from my perspective. I think it is that there is not enough resolution to make the heli look clear when it is 3 or meters away. I have a 1440x900 15" display on my MBP but that seems insufficient. I will try it again on my 21" 1920x1200 display on my linux box but I don't see that as being a huge step up. I think I will just have to make the model a little bigger and see if that helps.

Thanks again,
David
Post Reply