Beauty and the Beast!

[crewchief]

Now that we've all had a chance to see bullaculla's new "Beauty", here's the BEAST!

Of the two Varios I'm refurbishing, this one has about 15 hours on it and so is probably the more "dialled in" of the two. This will reduce the learning curve since I haven't set up a gasser before. In the first two pics you can see the layer of dirt on the exposed surfaces with the canopy removed. The third pic is after I'd gotten it cleaned up, and pulled the exhaust & carb to check to piston for scoring,etc. Except for a bit of normal-looking discoloration on the exhaust side, it looks perfect.

I "reverse engineered" the electrics and besides upgrading to 2.4GHz, I think I will be able to simplify things by using the AP2000i for mixing, since it has a 4-servo 90-degree configuration that the Varios use. The way these are set up, the nick & yaw channels from the Rx are first routed through the FMA CPD4 Co-Pilot 2-channel IR stabilizer, the output of which is combined with the Rx Aux 1 collective pitch and run into the Vario mixer, which converts raw nick/roll/pitch signals into CCPM 4-servo 90 degree setup. The AP2000 should combine the CPD4 and the Vario mixer into one unit, and will be a more modern setup. [Right, Mark? More AP2000 orders coming up!]

The previous owner said flight times were limited by the NiCd Rx battery. I hope to go to a high-capacity LiPo 2S2P or 2S3P with a BEC and get full 30 minute flight times.

The Beast weighs about 16 lbs right now without fuel or battery. The last picture shows the relative size of the semi-symmetrical 820mm Vario blade with a T-Rex 600 blade. The Vario blades have a complex NACA airfoil design.

The previous owner had the tuned exhaust specially built, but never flew it. Can't wait to hear that THAT sounds like! Any expert advice greatly appreciated!

[bullaculla]

Wow! now thats a monster :D
you got to get some video up when you get it running. I really want to hear that pipe! :)
You could wire up an eagle tree between your RX and Lipo to figure you flight pack draw. Must be nice to have that kind of flight times.

[Cryofix]

What about a generator system?

[JWatson]

I myself just finished going through a 8300 Benzin and Refurbing it to a 8301. While it was an expensive endeavor, I learned a lot about the machine and its in's and outs. It probably would have been cheaper just to buy a new kit!

I use it for AP work and I have since completely retired the Predator. It is truly a beast and It fits the Mission quite well!!!

Enjoy!

Jarrett W.

[kgfly]

The previous owner said flight times were limited by the NiCd Rx battery. I hope to go to a high-capacity LiPo 2S2P or 2S3P with a BEC and get full 30 minute flight times.
You could go with 2s2p 4600 A123 and avoid having a regulator (fewer failure points) and lower fire risk too.

[Wbird]

A rig like that my first thought was "Generator" and then as I scrolled down I see Cryofix has already suggested the same idea. Why bother adding a heavier battery and still have to charge it. A generator will likely not be much heavier than a bigger battery and then it is just gas and go.

My $0.02

[crewchief]

Thank you all for your suggestions about the batteries, regulators, etc. I'd heard about the gasser generator, but I haven't seen any specifics on it yet. I can see why they came up with the idea. My concern is that it would have to be installed as you build up the engine and frame?

[Jay]

Very nice, those Varios are bullet proof, one of the best designed gassers on the market.
Would like to see a video posted when you get it flying, and let us know how you feel about the performance with the pipe.

[crewchief]

I spoke at length with Joe Howard at East Coast Vario/Joker-USA today. He said the generator mounts behind the engine and tends to interfere with the standard exhaust/muffler, but it othewise works well. It wouldn't affect a side pipe. They probably extend the jack shaft and add another drive belt below the primary pulley to drive the generator.

But he said what they normally do with their big scale models, like the 36-lb Sikorsky Sky Crane, is run 2 x 2400mAh NiCd battery packs in parallel, both with their own off-on switch. The first one connects to the normal Rx battery in, and the second one attaches to any spare channel out. I hadn't thought about that approach! Guess you can put power in just as easy as getting it out of the channels. He said this gives them redundancy (although I would think a diode in each circuit would be needed to keep a failure in one battery pack from draining the other). They're also running extra gyros for the flybarless head and 140 oz. servos all around. He said this setup gives them 45 minutes of flight time and it only takes 15 minutes to recharge.

[kgfly]

(although I would think a diode in each circuit would be needed to keep a failure in one battery pack from draining the other).
You might find the topic on parallel packs on this page interesting:
http://www.rcbatteryclinic.com/
http://www.rcbatteryclinic.com/parallel.html

[crewchief]

You might find the topic on parallel packs on this page interesting:
http://www.rcbatteryclinic.com/
http://www.rcbatteryclinic.com/parallel.html
Thanks!

[jascamera]

Don't A123 have a quick drop in voltage near the end of the pack. I have seem some graph of the a123 on a Heli, toward the end, the voltage drop very fast. I am planning to use a Western Robotic Hercules 5A, (people cliam it's one of the best BEC) with a 11.1 v lipo. I am sticking to what I know best lipo and BEC and all the electric guys are depending on BEC and Lipo, so I think it should be fine. Unless generator, which I don't know much, with my luck, I probably get into more troubles.


Can someone explain more in depth on how to correctly parallel 2 packs for added protects?? What parts needed etc?

[Wbird]

Interesting findings about the generator. I guess running redundant batteries with 45 minute flight times and 15 min charge is almost like having a generator. Sounds like you are on the right track. Can't wait to see pics/videos.

[kgfly]

Don't A123 have a quick drop in voltage near the end of the pack.
Sure, when you are down to the last 10% of capacity! So do NiXx. However all LiXx (including A123) have a much flatter discharge curve at the low drain typical of an Rx pack than NiXx.

They also have much, much lower impedance than NiXx which means no risk of brown outs. You can pull 40A from a 2s A123 pack and still be above 5V. With 2s A123 you can run your electronics without a BEC or regulator and so eliminate all the associated risks.

If you leave your heli turned on and run them dead flat there is no problem as A123 tolerate 100% discharge without damage. If you overcharge them by a few volts there is no problem. They don't care about being partially discharged or frequently topped up and should give you about 1000 cycles.

A123 have very low self-discharge so can be put away charged and pulled out months later ready to go. They can be charged in minutes if needed.

Plus, if you get stuck you can use a handy 4s A123 pack to start your car ;)

[crewchief]

First milestone today - I overhauled the fuel system w/ new tank, lines, filter, etc., and with just the throttle and T/R+Gyro channels temporarily connected, I started Beast #1 today for the first time. After 3-4 years of sitting, it fired on the third pull. I ran some idle/low speed tests and tightened up the exhaust system. Later I ran some high speed tests with the head loader. I'm running it pretty "fat" (32:1) right now with Blue Marble Oil, so it's smoking a lot, plus burning out all that oil I sprayed into the cylinder beforehand. My next job is to get the needle settings dialled in.

http://youtube.com/watch?v=OtUF72Mj_mo
http://youtube.com/watch?v=ZiTQte6m4t0