Hughes 500D Mechanism: T-Rex 600e or Raptor E620SE ?

[Lon33]

The Hughes 500D is designed to be fitted with a gas or nitro mechanism. But I want to build it with an electric mechanism. I know some folks have fitted it with a T-Rex 600e, with some modification necessary, in part because the T-Rex has an underslung flybar which could be too close to the top of the body. The Hughes Mechanism Mounting Template shows exactly how to mount a Raptor 50 (which has a flybar above its rotorblades), and I'm wondering whether:
- anyone has mounted a Raptor E620SE in the Hughes 500D? or
- anyone knows whether the Raptor 50 is so close in size to the E620SE that it too ought to fit in the Hughes 500D?

[skyhunter357]

I have my raptor install on MD500E with raptor e550, I have extend the boom to 620 to fit nice and tial wont look short. it fly great.
Now in the proses of installing trex600E.

see my video http://www.youtube.com/watch?v=GuGIytC84WI

skyhunter357
www.fly.to/dangel

[Lon33]

Thanks for your response skyhunter. Your video looks great.

When you installed your eRaptor
- did it fit just the way it would have, if it had been a gas Raptor 50 instead of an eRaptor?
or
- did you have to modify the fuselage in order to get it to fit?

[stevehonn]

I've just test flown my E550 with a Funkey Hughes 500E fuselage fitted, although unpainted so far. The Funkey fuselage has holes for the Raptor 50 frame mounts but I found that the E550 frames are shallower than the Raptor 50, measured from the top of the upper main bearing to the skid mounts the E550 (and E620) is around 20mm shorter but there were sufficient spacers in the fuselage kit to mount it. The upper body mounts are mounted to the rear engine plate screws and are lower than the Raptor 50 so I added plywood plates to drop them down. I've used a Raptor 50 tail boom and belt so the boom is long enough, the 620 should be fine as I believe the 620 boom is 20mm longer than the Raptor 50 boom (the Titan boom should be the same) and you need to cut 38mm off the end of the fibreglass boom to fit the shorter length. The fitting was actually pretty easy and it certainly copes very well with the additional weight. I'll try and post some pictures later.

[Lon33]

Thanks for that information and for the photos.

How will you change the battery, while you're in the field flying?

Others who have used a T-Rex 600 rather than an eRaptor have said that one reason they've done so is because the T-Rex battery is easily to get at through the Hughes window, while the eRaptor battery is difficult to change in a Hughes fuselage. The battery-access issue may just affect the E620SE, which needs a 10s battery and carries it under the main rotor rather than in front where the T-Rex battery rides.

[stevehonn]

The front section of the canopy is mounted using 10 spigots around the perimeter of the joint. The two spigots at the middle on each side have been drilled through and I use two buggy body 'R' clips to retain it, easy to remove & refit and secure enough that there are no vibration problems.

[daniel reese]

as a side note about putting TRex600E in either the Funkey, Century or Thunder Tiger MD500 variant fuses; the flybar clearance is not an issue.

Before you blow your top, let me say that I currently fly an unmodified TRex600 electric in the Thunder Tiger MD530 (remodeled into a civilian variant) with no problems.
http://i129.photobucket.com/albums/p232/daniel_reese/T%20Rex/CIMG0666.jpghttp://i129.photobucket.com/albums/p232/daniel_reese/T%20Rex/HPIM1421.jpghttp://i129.photobucket.com/albums/p232/daniel_reese/T%20Rex/HPIM1304.jpg

And I aint putzing around doing flat ovals with it either!
Video from 15 October
http://video.google.com/videoplay?docid=-7997865585192019239&hl=en

True enough, when sitting on the bench, you can tilt the flybar below the "doghouse" but in flight it will never go nearly that low, no matter how hard you fly. Try this experiement. With the mechanics in the fuse and the swash at it's lowest point of travel, measure the distance that the flybar will have to move in order to contact the "doghouse".

Now, apply that same measurement to the main blades. Notice, that in order to drop that far, the mainblades will have to have intersected the tailboom. Since the flybar operates in a virtually parallel plane to the main rotor, it cannot deflect sufficiently to contact the doghouse without having first suffered a mainblade to tailboom srike. In other words, the main rotor disk will have to deflect rearward and literally cut through the tailboom in order for the flybar to even touch the doghouse.

In actual flight, even extreme 3D flght, the rotor disk seldom deflects more than 2" at the tips, let alone far enough to have a boom strike. When flogging the crap out of my Trex600/MD500 the flybar has never come anywhere near the fuselage.

The only caveat to that clearance issue is to be sure the flybar is mostly level before you spin up as there is a slight chance that if the flybar is tilted all the way over, you may get the flybar to tap the doghouse on its first pass but by that time the rotor is usually sufficently up to speed that the flybar has leveled out.

There is no need to modify either the TRex mechanics, the mounting system or the fuselage in order to fit it to any of the current MD500 variants

[Lon33]

That's encouraging. I decided to use the T-Rex 600e, in part because there's so much online guidance and advice -- like yours -- on building the mechanics and installing them in a Hughes fuselage.

An article in the latest issue of Rotorword magazine suggested attaching a small bracket beneath the flybar, just to be certain it doesn't touch the fuselage even on spool-up. It sounds as though you avoid the need even for that simply by tipping the flybar into place, just before spool-up.

On another topic: What sort of camera do you have in your cockpit? It's an excellent video.

[daniel reese]

I read that bit about the bracket thing...that's a bit over redundant, even for me! Its too easy to just level out the flybar before you spin up. A well balanced head will naturally "lean" that way anyway and as soon as it starts to move it levels out on its own. Too easy.

Thanks for the video comp but Im still not satisfied with it...there's too much distortion when looking through the canopy...more on that later.

The camera is one of those "Flip" cameras. This particular one is the RCA Small Wonder from Overstock.com. I see the same cameras in walmart for about $100 but I got this one for $40 from overstock. Its almost exactly like the CVS disposable ones but its reuseable and has a USB port to download the videos it takes. (has about a 20 minute capacity)
http://i129.photobucket.com/albums/p232/daniel_reese/T%20Rex/HPIM1474.jpg

I accidentally discovered that, while it doesnt normally have a live-video output, if you have a video in it's memory, then insert the av cable, THEN delete the movie, it will start sending live video. Thats how I got it to send video out through the wireless transmitter to be viewed live and recorded on the ground. Its amost capable of first person piloting but for that distortion.

Ive tried a few other miniature cameras- id love to be able to downsize this thing a bit- but none of them seem to work with the On Screen Display telemetry that Im using (ACT Labs "Black Box"). The RCA camera has an NTSC video out signal of 1.05vdc but all the mini cameras that Ive tried have an NTSC video out signal of less than 1vdc. I can only guess that the output signal voltage is the problem. Until I solve that, im gonna have to continue to use the RCA camera. Yeah, I could mount it on the outside of the heli but that would ruin the scale look of the thing.

Any ideas?

[Lon33]

I have a camera just like yours, and it takes remarkably good videos. Because it's tall, I couldn't figure out a good way to fasten it to my T-Rex 450, so I bought an Oregon Scientific "helmet cam" as well. I then built a camera cradle out of light-weight plastic Tinker-Toys (actually, a competing company's product). And I strap the whole thing to the 450's landing skids. Works great, though the 450 isn't a scale model so I wasn't concerned about maintaining a realistic look.

In your case, I'm sure you've already considered all the possibilities. There really are only a few. Remove a section of the fuselage window, so the camera lens has a clear shot at what's in front and below. Mount the camera outside the fuselage, even though it'll ruin the scale look. Or buy a different and smaller camera -- especially because you like to transmit images to a base station on the ground. On the video.google page that hosts your video there's a link to another video that shows a very small, ball-shaped camera that's attached to the side of a scale heli in a way that looks quite "real."

[daniel reese]

Yeah, that ball camera is mine too. I used a micro wireless camera mounted inside a ping-pong ball. The only problem with that setup was that the camera's output voltage was too low to work with my telemetry and OSD unit...still hesitant to buy a new camera...need another wireless tx too so I can mount a camera in my rc airplane