Search This Blog

Wednesday, December 26, 2012

MXS Flight Test __ 60 Inches Of Awesome


 
Some of you might remember our last big MXS article, which was titled "MXS Flight Test __ 64 Inches Of Awesome" and are now wondering why this one is titled nearly the same, only with the wingspan shrunk to 60." For this report, we merely removed the MXS' optional "racing" wingtips, and now we have a completely different airplane, all 60" of it, that is.

The reason I am so late in following up on the original report is that while warming up to shoot video of the MXS without the tips, I flew the plane straight into the ground. It had been a beautiful flight. I was just starting to get the feel for the plane and was really digging it, and a simple snap roll just somehow went wrong and that was the end of my beautiful 60" MXS. Rest assured, the problem was all me. I just got too relaxed with the plane, got sloppy, and got dead.

Making things worse, 60" MXS sold out while I was actually at the field, so I had to wait until the next shipment. A month is a long time to be without your best plane and thinking about what you did wrong, but it was a good lesson.

The first MXS came out pretty close to perfect, which is why it hurt so much to lose it. However, the second one is even better, partially because the second production run us usually a little better after the factory learns so much from manufacturing the first one. The same is true of the build because I knew exactly what to do when I got the kit and it almost fell together for me.

Flying
As you may have read in the first flight report, the tips dampen the roll rate and generally slows the plane down a bit over all. Like this the MXS is a smooth and docile dream to fly. I am almost of the mind that it would make a nice 3D trainer this way. However, for me personally, I want my MXS' to be wild airplanes.

Without the tips the MXS comes alive. The roll rate goes up about 20%, and you'll see that in the videos when I roll it in a terminal velocity dive. If you take the tips off, be careful with the ailerons until you get used to it or you could very well over roll it. It is faster enough that all the timing is going to change on just about every maneuver. The MXS goes from a 3D trainer to a 3D beast. Roll rate is now super quick, much like the 60" Extra EXP.

 Also improved are snaps and spins. I was able to hit my snaps much cleaner like this and it was easier to make it come out exactly where I wanted it. With the tips I did not feel like I could snap it as precisely.

 Knife edge spins are almost too easy, much like they are with an Edge EXP. With the tips you have to finesse the entry, but without all you do is put the sticks at full left, full down, 1/8th left aileron, and about 20% throttle. Like this she will just fall in all by herself and KE spin beautifully. With more power the tail gets whipping around the nose pretty violently. We'll try more of those after the airframe gets scuffed up a little and becomes more eligible for abuse.



The biggest improvement was in Pop Tops. With the tips I could hardly get a full turn out of it, and I can't imagine how Daniel Holman makes it look so effortless. I tried carrying more speed, changing the timing.....everything I knew how to do, but she just didn't like Pop Topping with the tips on. Without it was a completely different story, and now does them with maybe ever greater authority than the 48" MXS, which does them rather impressively.


 
Without the tips I would say the 60" MXS has a perfect balance for me. With the added pitch authority I like this plane even better than the 60" Extra, which I truly love. It snaps and spins and rolls and harriers just right.
 
I  am as comfortable flying this plane as I am the 48" Extra EXP, which is really saying a lot. Obviously the bigger size makes it more smooth and solid, but the added pitch authority is something new in this size plane, and the increased agility really gives me a lot of confidence when I get it down on the deck.
 
I've said it before that I think this is the best plane ever, and I still think that.

I have not had nearly the opportunity to fly this plane as I would like, and I am really hoping to change that right after the first. I need to get out there and get some time on it before the 60" Lasers come in. We usually lose about two weeks in late January to could, wet weather, so I've got to get busy with this plane.


Workhorse Of The Year: 60" Extra EXP

 

While we got off to a slow start with the 60" Extra, she made up for it with a blistering summer. I tried to save the big Extra for special occasions, because I just love the thing too much. I intended to keep the wear and tear to a minimum because I wanted it to last forever. I am a bit weird for Extras, and with this one being so big and so beautiful, I didn't want to be beating it up every single day.

Of course, this had to change when I became fortunate enough to be included in the testing program for the new Torque 4016/500 Mk II motor, which meant lots of hardcore, wide open torture testing. At this point my best airplane had become expendable for the cause.

While I really did not want to wear this plane out, I think I was also reluctant to tear it up transporting it, taking it apart and reassembling it, etc. We all have a plane that we treasure, and this one is mine. Eventually I realized this was ridiculous, because I can build another one in seven or eight hours and enjoy the process anyway.


 
So, I just hammered the hell out of this plane all summer long. It routinely went out four to five times a week and put in six to eight flights every time. During the July break for eye surgery, I kind of lost track of how many flights we had done, but I gotta believe it was upwards of 200 or so,  maybe more....and that was just up until July. We still had All of August through October to hammer the crap out of the motor before it was approved for production.

In  the beginning this was not so hard on the motor because Florida spring is not too bad. The telling part was May through early September when temperatures would generally hover around 92-95 degrees with 90%-ish humidity. During August, stepping out my front door is like walking into a blast furnace, so you could hardly ask for a more torturous environment in which to test a new motor.



My job was to run the motor super hard and try to blow it up. This was a really good opportunity to flip to low rates and blast off some slow and point rolls, and do some big sky maneuvering. The Extra is the perfect plane for this sort of thing because it tracks like a pattern plane. I got my low rates dialed in just right for this and my precision maneuvers got much better as the program progressed.

The Extra will make you a better pilot anyway, and working on the precision aspect really tightens up your entire game. I flew pattern in the 80s, and you can't believe how much your precision game will fall apart if you don't stay on top of it. Having a good precision airframe also really helps with your 3D because it trains you to put the plane exactly where you want it to go, and to do it smoothly. Admittedly there's still a long way to go, but I think the Extra really helped me improve my flying all the way around this summer.

I took the big Extra out day after day and flew it harder and harder. This airplane was easy enough to get crazy comfortable with to begin with, but after flying it over and over I am so confident with this plane that I sometimes feel like I can set the transmitter down and will it to go where I want it to!



The 60" Extra was easily my hardest working plane in show business this summer. Generally I show a bit of reverence for the 60" class planes, but that had to go by the wayside to get the job done. I had to hammer it hard and often, and in the end, this plane turned out to make every bit as much sense as a 48" plane. There is the slight inconvenience of having to take it apart to get it into the car, but outside of that, the 60" Extra is dead solid reliable and doesn't really cost all that much more to put together.

Wear, Tear, And Restoration
Initially I intended this to be my special plane. I was going to be really nice to it and baby it and all, but it didn't work out that way, or even come close. It became an every day beater that I try to treat a little better than that.

I recently took it all apart, checked and cleaned everything, and put it back together for another year's worth of special abuse. Except for the scrapes I put on the SFGs doing slow rolls on take off, It looks like a brand new plane.
 
Oddly enough, the underside rear of the wheel pants are scraped up a bit too. In really hard tumbles and such, sometimes the wheel pants will swing down on the axles, and then they drag on the ground when you land! I just need to check the nuts that hold the axles on a little more often and keep them tight so the pants won't move around. It's just that I have gotten a little bit lazy with maintenance because the electrics require so little. It's too easy to just fly and forget about it.

Outside of that, this plane has never so much as seen a hard landing, simply because it is so easy to land. That, and I generally try to wheel land it because it does it so gracefully. She is still capable of sweet, smooth harrier landings as you can see in the videos, but it's still a lot easier on the airframe to slick it in on the mains. I like this plane so much that I never forget to take care of it and I never get careless and let it bounce off the ground.
 
You might notice the Extreme Flight decals on the wing. Those were left over from my 48" Laser EXP when I had B and E Graphix make up a special package for it. The blue was a near perfect match for the Ultrakote and it gave me a chance to try Rapic Tac decal application fluid for the first time. It's a little different and I like it.
 
 
The 60" Extra is a righteously wonderful airframe. I've hammered the crap out of it for a whole year and all it took to put if back into near new condition was a bit of Windex and a few touch ups with the trim iron.

Essentially, its just damm good airplane.


Check back soon for the build report on the red one.


Monday, December 3, 2012

Charging The Lithium Polymer Beast


Generally I try to stay away from technical articles about electric chargers and such because this is not my area of expertise. Mostly I try to keep the blog just fun, but you do have to charge your batteries and you do need to know something about it. I came into electrics knowing absolutely nothing about how brushless power systems,  Li Po batteries and chargers worked, and it's been a bit of a learning experience. Mostly I didn't bother memorizing all the formulas and math, and simply tried to learn what works in the airplane and at the field, and the following is how I have learned to do it, so far, that is.

Chargers
For years I have used the Thunder Power 610C AC/DC chargers, and those have served me really, really well. I can use either a 110V outlet, or even use my car battery to power this charger, so it is a very versatile unit.
 

 I also used the regular TP610C that was strictly a 12 volt unit. I still have two 610C AC/DC chargers, and I keep one under the seat of my car just in case I need it or one of my friends needs it. I've also got a second one I keep on the bench if I need to top a pack off real quick and don't want to go to the trouble of hooking up my more powerful system.
 
Both were reliable, hard working little chargers, but in the end they were still just that ....... comparatively little chargers without big power. For a lot of folks this is still just fine because the most common battery I see at the field is something like a 3s 2200 to 2700 mah. I can charge a 65C 2250 pack in about 12-15 minutes on a 610C, and this size battery is so inexpensive that you can almost have enough of them to fly all day anyway.

Where you need a lot of power is when you get up into charging something like a 6s 3850 pack. It takes my 610C about 1.5 hours to charge one of those, which is clearly too damm slow. I put up with that for about two days and decided it was time to get a fire breathing monster to charge those packs.

Having liked my 610Cs so much I wanted to stay with a Thunder Power charger (And so did Thunder Power!). I talked to my buddy Mark in service and he put me on to the Thunder Power TP820CD charger.

 

Now we are talking about a serious charger, but surprisingly the programming is very similar to the 610C, which itself is pretty easy to learn. As such, I was comfortable using this charger right away. I plugged it in without even opening the manual and understood it as soon as it lit up.
The primary difference, at least externally, is the TP820CD can charge two packs simultaneously. The difference internally is just how powerful this charger is, capable of feeding each battery a whopping 20 amps. Like this I can charge two 6s 3850 65C packs in 14-16 minutes, depending on how low the pack was beforehand. I can also charge my 4s 2700 65C packs in 12-14 minutes and 3s 2250 65C packs in about eight minutes! And remember, this is charging two packs at a time, and that includes charging different size and voltage packs at the same time.
 
Charging the packs fast like this means I don't need to take as many to the field, or even better I don't have to buy as many to begin with, which adds up when you are flying expensive 6s 3850 packs.  In fact, I now only need two of them instead of four. The difference would have more than paid for this charger.
 
Of course, there is a lot more to it than that because the charger does much more, and I am still discovering it. I just today played around with it a bit and figured out to use it to measure the internal resistance of the packs, and the good news there is that all they made it through the hot summer still in really good shape.
 
So, while I am still learning about this charger I am definitely loving it more and more.
 
The Solid Hobby Power Supply 
Initially I was powering my TP820Cd with a Feathermerchant 24 volt power supply, and it served me extremely well. It's a really good unit, though I have often wished it only needed one power outlet (instead of two) to operate. When I saw that Solid Hobby was manufacturing a Y-harness complete with on/off switch, I had to get one. I liked the unit a lot, except there was an awful lot of wire there. I suggested to Jeremy at Solid Hobby that the two cords coming out of the power supply be shortened, and then the switch could be velcroed to the top of the power supply. Jeremy swapped out my unit for the improved one at no charge, so I was pretty pleased with how I was treated. I believe all the switches now come this way.
 

 
Now I only needed to take up one outlet, and with the switch I wasn't having to unplug it every time I was finished. This new arrangement also tidied up all the wiring and made the whole thing much neater, which is exactly how I like things.
 
Later when talking to Jeremy via PM at RC Groups, he mentioned he would be manufacturing a 24 volt power supply, and incorporating a few improvements.  As pleased as I was with the other product, I knew I was going to want one of the The Power24+ supplies too.
 
Unpacking the The Power24+ today I was delighted to see how nice the thing is. Ok, I get it that no one goes to the field and says "Damm, you got a pretty power supply," but the truth is this thing looks real nice. It is a very well finished product. Initially I thought they had made an outer case, but later found out that each one is individually hand covered with black Ultrakote!
 
 
 
It did not take long to realize this charger was built for married men. My wife noticed right away the unit has little rubber feet on the bottom, and she remarked it's nice the thing won't scratch the kitchen counter! While that's practical enough, it is also nice this could keep the thing from sliding off the work bench. It also gets it up off the ground enough that it is much easier to get your hands around it to pick it up. This might seem insignificant until you get arthritis in your hands, and then it is a bit of a godsend.
 
Upon firing the unit up I could hear right away how much quieter it is. This will come in handy for guys who have to charge inside the house and don't dare disturb the Wifey's TV time. The fans also run at slower speed until more cooling is needed, and then they crank up.
 
Having been around racing and model airplane engines all my life, I have a bit of hearing loss. When there are too many noises everything seems to turn to mush, Around the field with the traffic and other noise, the cooling fans on a power supply make having a conversation around my pit very difficult for me. With this new unit I am sure that will become a lot easier.
 

As you can see, there are dual outputs, meaning you can use two chargers. In this picture, you will use the black outputs and the red outputs on the very left to run the power system as a 12 volt unit.

 
Here you can see the red jumper wire used to hook the two power units together and make a 24 volt supply. This is the way I will be running it with my TP820CD. Also note in the above pic the nice little shields over the cooling fan intakes. Every so often I accidentally stick one of my fingers in the fan on my other power supply while it is running, but you can't do that on this unit.

So far I have charged a few packs getting ready for tomorrow, but the real test for this power supply will be in the field. So far I am really pleased with it and look forward to seeing what she's got tomorrow.

Units will be going into production shortly. List price will be $110 for the power supply including the on/off switch + $15 for US shipping, so the total out of pocket will be $125.

 Also worth noting is that the Power24+ system comes with a one year replacement warranty, so you'll be making a safe investment in powering your models.