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HomeScale✈️AircraftScale HeliScale Helicopter Main Discussion › TRex Electric 600CF in a Thunder Tiger MD500E
08-02-2007 03:20 AM  13 years ago
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Daniel Reese

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Urbana OH

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TRex Electric 600CF in a Thunder Tiger MD500E
I'd had this Trex for about two weeks before putting the fuse on- it just seemed too naked and the MD500 is the coolest helicopter ever!

After all the reading on this and other forums, I expected this to be alot harder than it was. The fuse is designed as a drop-in for the Raptor but fitting a Trex was nearly as easy!

The Raptor gets mounted to the fuse skid arches in place of the stock skids (in front). in the back, they give you a pair of brackets to fit those arches behind the mechanics. None of those line up on a Trex. So, I used 1/8" ply to make a full floor, reinforced it with two carbon fiber rods, then secured the mechanics to that. Amazingly, that allowed the mechanics to line up nearly perfectly with the fuse.

I secured the fuse landing skid arches to the plywood floor with supplied self tapping screws. Then I CA'd a pair of carbon fiber rods to bridge the space between the front and rear arches. The TRex mechanics line up almost perfectly with the front arch but the holes are offset just enough that were I to drill new ones, they'd run through into the old and make the whole thing useless. So I adjusted the position of the mechanics forward 1/8" and drilled down from there. That new hole was just barely in the skid arch so I laid a bead of JB Weld putty along the arch to reinforce where the new holes are and ensure the screws had something to bite into. The carbon fiber rods were spaced so as to fit as far apart as possible yet remaining under the mechanics- there's a small gap molded under the baseplate that was just the right space for those rods. I wanted to use CF to bridge that gap since the mechanics weren't going to reach to the back skid and I didnt trust the plywood to hold all the weight alone. The rear skid mounting holes on the Trex mechanics bolted through the plywood and into a CF cossmember thereby sandwiching the plywood between layers of CF rod.

THe fuselage supplies a pair of brackets to relocate the Raptor's canopy mounting holes and these fit the Trex perfectly. I used the Elevator servo's mounting screw position with a longer screw to secure the bracket on the right side, and used a similar screw with a spacer on the left side. These brackets lined up with prespotted (not drilled) holes in the fuse and were secured with self tapping screws.

The tail on a Trex is about 2" shorter than the Raptor Titan for which this fuse is made, (V1 and V2 will fit just as easily) so I had to cut off about 1/5" of the fuse's boom to clear the gearbox. I dismounted the gearbox to mount the mechanics- slid the boom through then mounted the tail gear box again. I moved the rudder servo forward; eliminated the forward servo mounting clamp and instead used a longer bolt with nyloc nut threaded through the unused hole in the frame's boom clamp with a spacer to maintain alignment. I made a longer pushrod from hollow CF rod and epoxied threaded ends on. The fuselage's boom tented to push up on the bottom of the mechanics boom, interfereing with the pushrod. THe supplied foam rubber spacer was intended for the very end of the boom and since I cut a bit off, it was too loose to be useful, besides, the hole for the pushrod was WAY too small. So, I cut a 2" x 3/16" groove from the bottom at the very end of the boom to clear the pushrod and secured the mechanics boom to the very top of the fuselage boom. This ensured enough space for the pushrod.

The mainmast lined up perfectly with the fullsize helicopter positioning with plenty of space for the antirotation bracket. I did have a tiny bit of interference from the front edge of the fairing that needed whittled out. Once sanded and repainted, it'll be hard to notice.

Many people have expressed concern that the flybar will hit the raised fairing at the rear of the rotor mast. Two common solutions are an extended mainmast or conversion to a Raptor head to put the flybar on top. My installation ended up having the flybar less than 1/4" below the fairing when lowered to full downward deflection. At lowest pitch (-2*)and full rearward cyclic, the flybar juat barely touches the body. In actual flight, with the dual rates on cyclic at 60%, it never comes close. Not even when doing full speed forward followed by full throttle rear, not when doing left and right turns as hard as I can. Now, Im not doing 3D but its flying a heck of alot harder than any REAL helicopter would and it never comes close. I was in the process of trying to find a raptor head or ordering longer mainshafts when I took it for a test flight. That was 4 days ago and after 4 days of flogging the crap out of this thing, the flybar never comes close to the fuse. Im going to pass on the raptor head and the extended mainshaft until I decide (if I ever do) to increase negative pitch- bringing the flybar closer to the fuse.

I also installed a Revolution micro antenna and a wireless color camera in the cockpit. This is the camera setup on my TRex 450

The only thing left is the upgraded wireless downlink with better camera and blackbox telemetry overlay...and paint. I had always inteded to make this a civilian model sice the olive paint makes it terribly hard to see below treeline!

For most of the flights, I strap in my HP digital camera over the battery inside the canopy for a pilot's eye view of the flight.

So, enough talking- heres the pictures and videos!

Here you can see the flybar issues

This thing is HUGE!

Fitting the batteries is done through the front doors. A bit tight but doable.

Here's the HP camera in position

And here's the videos:
Initial testflight with onboard camera
http://video.google.com/videoplay?d...150984126125040

Just hovering
http://video.google.com/videoplay?d...530157304684491

Doing flybys on my camera man
http://video.google.com/videoplay?d...920421061703779
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08-02-2007 04:10 AM  13 years ago
w freeman

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Mt.Pleasant, Texas

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cockpit video is great
Except for a couple of fingerprint smudges showing up at the nose of the cockpit, your video is remarkable. I have seen a lot of flight videos from r/c helis, but yours was perfect. Realistic sound too.
I am a scale heli guy. I was a flight medic for several years, and the approaches over the buildings, are very realistic. Brought back memories, landing on heli-pads / hospitals, and from an R/C heli at that. Suggestion, make yourself a heli-pad to approach for your landings, and you will have icing on the cake.
Good job.
w freeman
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08-02-2007 05:01 AM  13 years ago
Daniel Reese

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Urbana OH

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Thanks!
I cleaned the window later, after seeing those smudges. That's not real high quality plastic so there's a fair bit of distortion around the molded window frames but it'll do fer now.

The sound was one of the first things that shocked me about the 600 Electric- it sounds just like a turbine- not as loud as a real RC turbine but alot less fuss! I just picked up the helical main gear and pinion and torque tube tail drive. When my lights arrive (this weekend I hope) I'll finish off the details and paint it. Should work out pretty well.
Thanks again for the compliments.

For anyone considering an MD500 body, I highly recommend the Thunder Tiger version. Its not as finely finished but any basic modeler can do that. It fits easier and costs alot less than most others. Its weight is remarkably light as well! I didnt have a scale with me at the LHS when I was comparing them but this was significanly lighter feeling than the century and funkey bodies.

I'll have better pictures of the internal construction when i tear into it this weekend.
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08-03-2007 11:56 AM  13 years ago
doorman

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Sherwood, Arkansas

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Nice Conversion......
Looking real good and a clean installation.... that is a real good thing....it shows that you thought it through prior to mounting everything solid... Very nice and thanks for the info....

Stan
AMA 2918-Team Spin Blades,,Castle Creations, Unique Aircraft
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08-20-2007 07:50 AM  13 years ago
Edwardp

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Malaysia

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Glad you went ahead and did it, Daniel!! And nice vid as well! Congrats!
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08-20-2007 03:34 PM  13 years ago
Daniel Reese

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Urbana OH

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Updates on the MD project.
After proving the fuse & mechanics combination I took it all back apart, added the lighting, the telemetry sensors and paint.

Here's the latests flying video
http://video.google.com/videoplay?d...661875332192839

Also working on a co-pilot driven on-board camera. The wireless camera used in this test has very poor image quality but did prove the concept.
http://video.google.com/videoplay?d...142124849849925

Here's a test video of onboard video taken with the RCA SmallWonder digital video camera, with the ACT Labs Blackbox telemetry overlay. The video sux cause I didnt have a fully charged battery on-hand for the wireless transmitter and its taken through the plastic window of the cockpit. If the weather holds, I'll test it again tonight and should have much better results with a full battery.

I found a better micro camera with comparable image quality that could be mounted beneath the fuselage in an "IR Camera" housing or on an outrigger in the same scale appropriate housing but at the moment, Im having camera / blackbox compatability problems with it.

However crappy the video (because of low battery voltage) it does show the feasability of barometric altimeter, rotor RPM, wireless tx voltage and helicopter rx voltage monitoring and recording during flight. Barometric altimter is only accurate +/- 10' but in actual performance, accuracy seems to be within +/- 5'. The speed is not feasable to measure- the sensor is a pitot tube but since a helicopter seldom travels far in a true nose-truely-forward attitude, air is seldom being pushed directly into the tube. On some real helis,that tube is on a swivel to keep it properly aligned- thats impractical at this scale. I guess I can do without knowing airspeed. Rotor RPM is detected with a photocel mounted inside the "cockpit" looking up through the rotor disk and appears to be accurate based on mathmatical calculations of what it aught to be. Wireless TX votage is handy, as is helicopter rx voltage for obvious reasons.

Anyway, here's the video
http://video.google.com/videoplay?d...668152020998056

Nearly done! Once I get the camera bugs worked out I'll be considering one of the attitude holding units out there ("autopilot" and a 5 bladed main....but that's down the road a bit.
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08-20-2007 07:32 PM  13 years ago
jetscan

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Netherlands

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Fantastic job! The lights are without a doubt the finishing touch

Looking forward to more photos and videos
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08-21-2007 12:01 PM  13 years ago
Daniel Reese

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Urbana OH

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Went back up for three packs testing the telemetry & onboard video. (I'll upload the video as soon as I can). There's still a small bit of video glitching but I think I can blame that on HighFreq. vibrations from the rotorhead. (blade grip tension & blade alignment issue)

The telemetry overlay was performing perfectly (except for airspeed of course) and the video quality (other than the occasional glitch) was improved over the first test.

Reached 107' over my apartment yesterday. In a better location, I could easily go much higher. Once above ground-level obsticles, it looks like this system could be used for FPV flying....but Ive got to resolve the video glitch problems first.

The vibration problems are either in the telemetry device or the wireless transmitter as Ive used the camera mount for many previous flights with no problems. Earlier versions of wireless video tested on this helicopter had the same glitch problems with vibration that were solved by a solid mount of the wireless tx. At present, the tx is secured on a velcro pad- I'll try a solid mount to the cabin floor and retest when the rain stops.
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08-23-2007 11:55 AM  13 years ago
Daniel Reese

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Urbana OH

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Couple of solutions and a few new problems on the MD500.

I got the airspeed working- turns out I had the internal tubing going through a sharp bend. That, coupled with what appears to be a 3-5 second delay from start of forward motion to displayed airspeed. Before yesterday, Id never had the space (courage) to be flying straight forward for more than 3-5 seconds- I was always getting too close to the treeline. Yesterday I worked out a different flight pattern and had the guts to let the TRex600 off its leash a bit more and it finally started registering airspeed. On average, I can get it up to about 30mph before I have to make a turn back inbound. Still not comfortable above 100'AGL.

So, while the telemetry has been resolved, a vibration issue has reared its ugly head.

Previously, id had a vibration issue in the main rotor due to the blade grips being too loose- allowed the blades to flap too much never holding them in place firmly enough. After adding a fraction of an ounce to the the blade bolt torque the vibration went away. Ive noticed the grips getting a bit loose again and suspected that was the source of the vibration. However, in this case, it is not the only vibration.

There appears to be a "notchiness" in the torque tube take-off gearbox. I'll have to do a full overhaul to track it down and Im NOT looking forward to that. Ive only had about 5 hours on the torque tube- it shouldnt be worn out yet...maybe its something else.

We'll see.

The 2.4ghz downlink is glitching pretty bad still too. I had suspected it was due to vibration but I did a hand-carried range test with different power sources and they all had similar results- glitching, or rather break-up/cut-out of the video signal happened as little as 50' from the reciever. Seems to be a tx/rx signal strength/clarity issue. Im gonna look into some patch antennas- there's a nice low profile (3" circular) one that should amp the signal from the tx nicely and would look pretty scale-like under the fuse. The rx patch antenna 98" square) would add even more clarity to the signal. That should help clear out the video problems. The two antennas would only be about $100. Not too bad if it works.
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08-23-2007 11:57 AM  13 years ago
Daniel Reese

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Urbana OH

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EDIT....rx patch antenna ( 8" square )...dumb-thumbed the keyboard...
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08-24-2007 12:44 PM  13 years ago
Daniel Reese

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Urbana OH

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Some stills from telemetry testflights

Here I was altimeter and RPM sensors

Both are accurate, I just wish the weather had been better- cloudy rain-threatening days make for poor photo ops.

These next two are from the airspeed testing. I hadn't bothered to calibrate the alitimeter so disregard those readings. The other fields are accurate though.

Still need to sort out a vibration problem that I suspect is in the torque tube take-off gearbox and make a prettier spotlight mount and remote camera mount. A micro camera housed inside a ball will be modeled to look like the IR or HD camera balls on full size helicopters. Will be pan & tilt capable, driven by a copilot and monitored on a seperate monitor. Ive sorted out the mechanics of it, just need to sort out this video cut-out problem before I continue
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08-24-2007 02:14 PM  13 years ago
Heli_J

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Kannapolis, NC - USA

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all i can saw is AWSOME!!!!!!!!!!!!!!!!!!---> Blade CP, T-Rex, MX-400, QJ-8, QJ-16 No Gass, only Electric!
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08-25-2007 04:54 AM  13 years ago
Daniel Reese

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Urbana OH

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Thanks...
Still struggling with this vibration problem...it didnt do this before the torque tube and I dont think it did it right after installing it...sorta crept up on me since then. Ive only got about 5 hours on that torque tube and helical main conversion but there is definately a problem in there somewhere.

I tightend the blade grips and that reduced the vibes but only marginally so I tore it all down again. I suppose it doesnt hurt to have a full overhaul every once in a while.

There's a faint dusting of white powder on the torque tube take-off gear housing. Looks like the gear that meshes with the lower main and the tail driveshaft is grinding a bit. Im starting to suspect a combination of problems.

Now that its torn down, there's definate play (0.25mm?) in the mainshaft bearings so those will get replaced and when I spin the take-off gear, the output end of the torque tube drive shaft is wobbling...bent drive shaft? How the hell does that happen?

Thinking about going back to belt drive and flipping the tail rotor while Im at it...maybe. The thought of having a belt driven tail when I cant visually check that belt for wear and tension scares the crap out of me. Especially considering all the money wrapped up in this bird.
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08-25-2007 08:39 AM  13 years ago
Daniel Reese

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Urbana OH

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Fixed it.
The three main bearings were shot. Those, a new mainshaft, main gear, lower gear and one-way and she runs smooth as glass again.
I love this helicopter!

Only the bearings were bad but I have a bunch of em so I swapped out the mainshaft. The gears and oneway were a pain in the arse to get in the first time and that may have contributed to some of the problems so I just went ahead and pulled them out & replaced them too.

I had to completely disassemble the heli for this overhaul so I made the best of the opportunity and checked every nut,bolt and screw on it. Should be fine for a while.

I chickened out on the belt-drive tail and just kept the torque tube even tho there's a pronounced wobble in that driveshaft...yeah, yeah, I know...I'll just order a new driveshaft and carrier bearing and change it out when it gets here.
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08-31-2007 04:21 PM  13 years ago
Pyrock

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SF Bay Area

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Great stuff...does anyone know if the 530 adapts to the Trex600 as easily as the 500?Trex 500, Stretched Logo 10 3D, Ion-X, Gaui 200
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09-01-2007 06:09 AM  13 years ago
Daniel Reese

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Urbana OH

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um....thunder tiger calls this heli a "MD530". The rest of the world calls it an MD500....your choice I guess.

Yer talking about the same thing.

Yes, the fuse you asked about, the same one I used, WILL fit a TRex600CF as described above.
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09-05-2007 11:16 AM  13 years ago
toast

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Taranaki - New Zealand

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Daniel - Cheers for taking the time to write all this down. Ironically I have just started work on exactly the same project after killing two scale hielis in a row due to engine failures (Caliber 5 in a Funkey Airwolf and Raptor 50 in Funkey Jet Ranger). I figured it would be nice to convert to electric power for the reliability, cool sound, and lack of smoke and oil! You have really given me the push I needed. Now with a reliable platform to work with I can get into some interior detail and weathering. I will also be running JR/Spectrum for added peace of mind...TT50, TT90, Cal5/Airwolf, TT50/Jetranger, Zoom400/H500, Trex600/Apache, SSM UH-1, and more!
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09-05-2007 08:05 PM  13 years ago
Daniel Reese

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Urbana OH

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If there's anything I would do different, it would be with paint. I used a primer over the factory paint and then my own paint. That's alot of paint and alot of weight.

Next time..maybe this winter, I'll strip it totally down and repaint it.

Weight is the only problem Ive had with this build. All up its pretty heavy, near double that of a stripped TRex600. The 600L motor, 75A ESC and 6A BEC with 6cel batteries seems to run ok. Flight times are about 5-7minutes.

I have two DN 22.2v, 6S2P 4400mah 20C batteries that give about 5min
Two Align 22.2v 6S20 4600mah 20C batteries that give about 5min too
One Align 22.2v 6S1P 4600mah 20C battery that gives about 5 min

Best of all is the AirThunder 22.2v 6S2P 5000mah 25C battery that gives over 7 minutes.

I run all these batteries with a Lipo alarm that triggers when any single cell reaches 3.75v, and I land immediately. I use a timer only to track battery performance and use.

At the end of a flight the 600L motor is pretty hot but the ESC never has been. Its got plenty of power and has never let me down. Ive reached speeds upwards of 47mph and altitude in excess of 115' AGL.

A rock solid performer on a budget. I love Align and AirThunder! And God Bless GrandRC.Com!!!!
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09-06-2007 07:10 AM  13 years ago
Edwardp

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Malaysia

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...I run all these batteries with a Lipo alarm that triggers when any single cell reaches 3.75v, and I land immediately. I use a timer only to track battery performance and use....
Great going there, Daniel!

Yeah, a lipo alarm! Got to get me one of those!! But 3.75V? Isn't that a little too high?

My 5400mah on my heavy scale A109 Rex600 gives me 8mins. The same batt on my other MD530 Rex600 will provide 10mins flightime. Both cutoffs at 3.0V per cell. Pack seems ok after 40 or so cycles.

I've just ordered 2 new Aplus 6S1P 22C 4500mah packs(abt 400gms heavier) to run in parallel and I'm expecting these to provide an easy 12mins of fun on the A109!
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09-06-2007 05:14 PM  13 years ago
Daniel Reese

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Urbana OH

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3.75 is indeed VERY high for a cutoff but I like it that way. Lipo's are WAY to expensive to risk damaging them and Id rather land and swap batts than risk ruining one. 5-7 minutes is about all my nerves can handle sometimes- I fly it awfully hard, especially the AirThunder 5000mAh battery...

When you double the packs, you're adding significant weight to the airframe, wont that seriously impact your flight time? I wonder what the point of diminishing returns is. There's a point, somewhere, when the increased capacity of mulitple batteries is not sufficient to overcome the increased weight of those batteries.

On my setup, I dont think I could fit another 22v battery in there. Maybe the DN batteries- they're the smallest ones Ive found but then the nose would get awfully heavy...You'll have to let us know how that goes! Include some pictures of how you placed those batteries.

Here's some videos of the MD500 gettin flogged around FT Belvoir, VA
http://video.google.com/videoplay?d...680848700471234
http://video.google.com/videoplay?d...505767122406363

Here's one with the video run through a telemetry sensor package, then wirelessly transmitted to a groundstation where I recorded it.
The video quality aint all that good but the telemetry data is interesting enough
http://video.google.com/videoplay?d...631037266144887

Still having video cut-out problems. They're related to vibration but not entirely caused by vibration...I put a 7db gain ant on the rx end but still might need something on the tx end.
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HomeScale✈️AircraftScale HeliScale Helicopter Main Discussion › TRex Electric 600CF in a Thunder Tiger MD500E
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