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CDE vs HDE?

Old 10-13-2006, 02:59 PM
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gsk11740
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Default CDE vs HDE?

I'm thinking about getting a T-Rex 450 XL after reading the reviews in a RC mag. What's the differences and Pros/Cons between CDE and HDE types? Also, where's a good place to get one?
Old 10-13-2006, 04:57 PM
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NVSFlyer
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Default RE: CDE vs HDE?

The HDE is a bit heaver but for me it was the easiest to set up, since the servos aren't linked together. The CDE uses 3 servos together to move the swash up and down, they circle the swash plate. Where as the on the HDE it uses 1 servo to move a platform that the other 2 servos sit on. The CDE uses the TX to mix the signals so that all 3 servos move different amounts depending on which way the heli to go. If this is your first heli then I would try and find a LHS that sells them and see what type of support they will give you in the set up. This is also a good place to start and compair prices for extra parts.
Old 10-13-2006, 07:45 PM
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WhtBronco
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Default RE: CDE vs HDE?

They both fly the same once setup properly. IMO the HDE is easier to setup, some of that is from having flown a Raptor 50 for a while and the HDE is nearly the same. I still think setting 1 servo is easier than 3 at a time, but that's just me.

All in all go with the 1 you like best. If you look around this forum you will find links to videos made by Finless and he did a very nice job of explaining how to setup the T-Rex helis. You'll also find lots of posts on the CDE vs HDE.

Whatever you do get good electronics. Helis can't get by with cheap electronics like servos.
Old 10-14-2006, 08:37 AM
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gsk11740
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Default RE: CDE vs HDE?

ORIGINAL: WhtBronco
Whatever you do get good electronics. Helis can't get by with cheap electronics like servos.
Yeah, I learned that lesson the hard way (and lots of others). I bought a Walkera 36 a while back and made the mistake of trusting the stock electronics. I'm now a survivor of "The Rabid Dragonfly Attack"

I plan to run a Spektrum DX6 (eventually for all my stuff) which I read somewhere doesn't handle T-Rex CDE too well. Something about slower cyclic response. Since most of what I plan to do is just flying around (no 3D) I guess HDE should do fine. I'm curious though can HDE be converted to CDE in the future or are they totally different frames and all?
Old 10-14-2006, 05:16 PM
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Default RE: CDE vs HDE?

Align does sell a HDE to CDE conversion kit. I think it sells for around $30.
Old 10-14-2006, 08:07 PM
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Default RE: CDE vs HDE?

ORIGINAL: ultraviolet

Align does sell a HDE to CDE conversion kit. I think it sells for around $30.
Cool. While I think the HDE version would be good for me it's nice to know I can change it in the future if I need to. Thanks!
Old 10-18-2006, 08:16 PM
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Default RE: CDE vs HDE?

Newbie here and was wondering what is CDE and HDE?
Old 10-19-2006, 04:59 AM
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Karyn
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Default RE: CDE vs HDE?

ORIGINAL: redhotzx9

Newbie here and was wondering what is CDE and HDE?
HDE
On a standard fixed wing aircraft you have one servo to work the elevator, one servo to work the ailerons. HDE is the heli equivalent, but you add a 3rd servo for collective pitch. It is easy to setup the TX as each function operates just one channel, but the mechanics on the heli can get a little complex. You usually end up with a see-saw (teeter totter?) setup with some of the servos mounted in one end. The collective pitch servo tilts the see-saw to move the swash plate up/down along with the elevator/aileron servos.
Simple TX setup but lots of moving parts.

CDE
Still uses 3 servos like HDE, but each servo is connected via pushrods and levers directly to the swash plate. Levers are required because of the servo placement. In order to alter collective pitch all 3 servos work together. To alter elevator, 2 servos work together and the 3rd turns opposite direction. For aileron the 2 servos attached to the sides of the swash move opposite ways while the 3rd stays still. The mixing required to make the servos move like this is done in your TX. The advantage is better control response as you have the power of 3 servos for each control, (2 for aileron).
More complex TX setup, less moving parts.

A variation on CDE is used in the Trex SE where the servos are mounted in such a way that they can be directly connected to the swash with just a single push rod each and no levers.
Same TX setup as CDE but very simple mechanical setup (no levers, just one push rod).


Advantage for HDE is simple TX setup and the fact that you can use a mix of servos as they're independant of each other. CDE requires all servos to perform equally and 3 cheapo specials from ebay, even if they look identical, are not guaranteed to move at the same speed.
Old 12-07-2006, 09:55 PM
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Default RE: CDE vs HDE?

I got a many questions about the motor setup and how tight should the set screw be on the blades? Any help would be appreciated
Old 12-08-2006, 12:59 PM
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Default RE: CDE vs HDE?

First off the HDE will fly aeobatics and 3D just as well as the CDE.

The main blades should e just tight enough that holding the chassis of the heli in you hand with the heli on it's side it takes a light bump to the skids to make the blades fall.
Old 12-08-2006, 01:46 PM
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Default RE: CDE vs HDE?

Some have said that the eCCPM mix in the SPektrum DX6 is slow and that the DX7 has fixed this. I have a DX6 and one eCCPM heli (blade cpppro) and one mechanical mix heli (MX400Pro/TRex mods) and I certainly can't tell the difference in speed of control response--but that maybe because the BCPP is very fast anyway and the MX400 is a bit slower to respond--maybe they cancel out.
Let you know when I get a DX7...

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