Electric vs Gas [Archive]

JettPilot

Sep 30, 2005, 09:09 PM

That is an awesome picture Dan, I didnt know there were other UAV people in your area...

For very small planes electric is the way to go... But for large UAV's, gas is better ;) I typically fly for about 2 hours flying time in an afternoon that I fly my plane. I have a Zenoah G-45 on my UAV which has LOTS of power and will fly my 20 pound plane around with authority for an hour. To do the same thing with electrics, the cost of the motor is about the same, but I would need at least 4 very huge LIPO packs which would cost around 500 dollars a peice. I wouldnt enjoy flying as much either because with electrics you always have to be careful with the throttle so you dont drain the batteries to fast :( . So that would be around 2000 bucks EVERY YEAR in batteries alone, because LIPOS just dont last that long :mad: Every time you even look at a LIPO wrong it swells or goes bad :eek: My Zenoah is trouble free, I never have to touch it once it was set up, and will last longer than I will live :)

Electric is the future, and I look foward to the day when I can stick a big electric motor on my plane at a reasonable performance and cost, but we are not there yet....

Myron

Sep 30, 2005, 09:52 PM

Hey Guys,

We'll chat here as to not hijack Scotts thread!

Dan,
Adding lead ballast to dampen vibration... EEEK!!! Using an O'scope to find the root of vibration...EEEK!!!.. Actually my large Slipstream will fly 2 flights at 12 minutes each and that is only on a 5000Mah pack... Now I do have two configs for that aircraft.. the 70" version flies the two 12 minute flights at an auw of 12.xx lbs.. The 87" version has flown at an auw at well over 15 lbs.. Keep in mind they use the same modular fuse so the power system is common as are all the electronics.

As for Pros and Cons, there are plenty to both and it is a matter of having the right tool for the job IMO.

The Key difference is that the energy density is way higher for gas or glow over a battery... However, keep in mind that an AXI 41xx series motor will put as many or more watts to prop than a G26 IF..IF..IF..you run a monster 37 volts to it.. that AXI motor weighs only 12 oz... the G26 is around 55.... This is where it gets sticky.. You have decide what works best for your APP...

PROS in electric for MY usage.. Please note the "MY"

NO tuning involved.. Ease of use basically
NO worries of a flame out.. Motor decides to go lean when you hit climb out
NO Mess. this one is self explanitory
NO CG change..exact same flight charateristics while your in the air..
NO vibration, considering you balance your prop and hopefully everyone does that
NO cumbersome gear to carry with you.. starters, fuel, spare parts
Deployment time... basically you can plug and go
You can shut it completely off in flight...
QUIET!!! Stealthy, less obtrusive
You can test run and configure in your house AT NIGHT!!!

there are probably more!

CONS:
POLY's!!!!
COST... We all know that big poly's and ESC's are pricey!
Life expectancy of polys is 1000 charge cycles or less... still cheaper than glow fuel in a long run though...
Polys' are NOT very forgiving.. hard crashes and mis-use kill them
Endurance.. BUT there is a breaking point.. Anything under 1 hour and less than a 17 lb model I will take E anyday.... Once you need long run times gasoline becomes the clear winner...
Interferace.. You e-model is quiet on the bench but power is hot.. you get a hit and you could be in for a BIG surprise..

There are probably more!

BTW: I also fly a 73" glow KATANA and a 82" Glow Cessna 182.. I love all my models!

Myron

LukeZ

Sep 30, 2005, 09:53 PM

Geez Dan, I don't know how you guys fly in such a confined space. Must be tough. ;) I can't wait until I save up enough pennies to leave the city and head back out to the country - even though I just got to the "big" city from the country two months ago. :rolleyes:

My preference really is for electric power for a whole host of reasons: torque, noise, no-slime, finer control, etc... Maybe also I was turned off as a kid by fiddling with those :censored: Cox engines for hours on end, trying to get them to run. Though I will say the smell of fuel really does take me back to that excited kid feeling...

I haven't built my UAV airframe yet as I'm doing the avionics first, but I think when I do it will probably have to be gas. My goal is long distance, about 2,500 miles, and although I have pie-in-the-sky dreams of doing it electric, I just don't think it's going to be feasible for a price I can afford.

But talking about people who see the benefits of both, an argument can certainly be made for a hybrid vehicle much like we have with cars now. The technology for hobby use isn't quite nearly as good yet, but especially for long distance I think that will become a more and more attractive option.

Luke

Myron

Sep 30, 2005, 10:01 PM

LUKE!

You bring up a very interesting point!.. Look at the work AZZA and Son are doing.
I think they are talking about using wet fuel to get them to a certain point, but then kicking in the E to get them to altitudes where fuel tuning and efficeincy become tricky..

Myron

kd7ost

Sep 30, 2005, 10:01 PM

Don't forget the credit for that pic goes to IVspark. He's actually about 250 miles away but drove out to meet and greet with UNAV folks as well as myself on a recent field demo day. Thanks IVspark.

I agree.

For the little stuff electric is great. For in town, over houses doing things like getting some low altitude video of a hazmat situation, etc, electric is it. I think it shines in the low range, low altitude, 30 minutes tops missions profiles.

But if you need to haul big stuff with power and do it all day long without having to take out a second mortgage, gas is the way to go. At three dollars a gallon it's still a lot cheaper than anything else. I get, hmmm, lets see, about 240mpg. If I run low I can land, top back off and go back up. I run NiMh battery packs and they can be charged at extremely fast rates. After accumulating 8 hours or better of flying I have to spend 40 minutes recharging before starting over for another 8 hours. I don’t think you could do that with electric if you had 10 grand to spend. Oh, And I can pretty well keep flying in up to and above 30 mph winds. It'll knock me around though and abuse the airframe quicker.

Dan

kd7ost

Sep 30, 2005, 10:14 PM

Dan,
Adding lead ballast to dampen vibration... EEEK!!! Using an O'scope to find the root of vibration...EEEK! Myron

Whats your point? The little 5mp camera was so light that it lacked inertia so it didn't compress the foam for vibe absorption. My camera mount, camera and lead added to it weigh less than a high end camera. I have many pounds of cargo capacity so a few ounces is not a big deal. It's certainly much less weight than a 5000mah battery pack. And while your 5000 mah battery pack might give you double your short flight time, the few ounces of lead I fly don't take any away from my long flight time. ;-)

I use an O'scope for many things. I'm just a geek that way.

Dan

kd7ost

Sep 30, 2005, 10:34 PM

Here's a recent picture of my Gasoline powered plane. No fuel residue.

Dan

typicalaimster

Sep 30, 2005, 11:36 PM

The only residue I'm getting on my Glow powered plane is on the tail. This is because it's in direct path of the exhaust. As for the rest of the plane, I spent more time wiping the dust off of it! I'm still trying to figure that one out.

Electrics have great benefits in the smaller versions. I prototyped with an electric one before moving up to the glow version to the plane. Electric is portable and is very 'plug and fly'. However I didn't like the whole wait for an hour to charge thing. Lipo's are very expensive. A normal day of flying for me now involves 4 - 15 minute flights. To do the same with electric I would have to invest in 4 Lipo packs @$100 a pop. The plane now has a high lifting wing. This would allow me to run a 3200 or 4000 mah pack for the main supply, and a separate 11v 1300 pack for the gear. I could do an electric conversion, but don't see the need right now.

Glow or Gas offers a technology that has been around for years. While I was flying my plane today, I had a guy come up and say wow I thought it was electric until you came down. The 4 stroke I'm using is very quiet. I'm thinking about adding the Genesys to the system to create power from the engine. This would allow me to charge my flight packs or run optional equipment. Most UAS's run video cameras in them. I don't see where vibration is an issue in this concept. If the camera is properly mounted then vibration is not an issue. The only reason I'm getting vibration is because I have my camera rubber banded on.

Having flown both, I don't see much of a argument of Gas vs Electric. I think alot of it now has to do with airframe and pilot. I draw my own personal line at '40' size. I think the electric technology is great for under that size. Above a '40' sized plane the up front cost of starting is out of my budget.

--Scott

CenTexFlyer

Sep 30, 2005, 11:38 PM

Glad you got all your business together, Dan... hope we helped in some way. My many discussions with executive managers in many areas has given me greater insight into what we are trying to produce and sell since we last talked in Reno.

The way we/everyone sees it, time is money. You tell me that you need a picture of XYZ, at this specification. I line up several "XYZ's" in a coordinated fashion and use an electric to go up and shoot said "XYZ" in the space of 10 minutes... not one hour. A LiPo can be charged and left in that state for a long period of time so if I have 5 missions per day (which is optimistic) I can probably pull off two missions per pack. If I am running intelligently, the packs are all on charge while I move from mission to mission. I know your saying, "but I don't even have to top my tank either...." but you still have more "fiddle factor" to deal with arrive on site and then we are back to that "time is money thing".

We need to think much further than just flying a plane on this level. Our end product is "data". Granted it is visual data, but nonetheless, it is still data. The ability to gather that data may require the use of a plane, heli, blimp or even mast. You have to look at it from a corporate standpoint and what is expendable and tax reducible. It goes much further than the debate of "gas vs. electric".

The marketing data we have gathered is that electric is "perceived" as being a more "green" method of gathering our data. I know, I know... all BS, but that is the perception. And it does play well. I'm not carrying a quart of flammable liquid that could torch my already parched corn/wheat/barley field if there is a crash. No denying it. You do NOT build a plane to crash, you build a plane to FLY, but you factor in that liability AFTER you reap the benefit of gathering the end product. With the aircraft we are capable of producing, covering 5 square miles just doesn't require the hosses most of us are putting in the air.

I'm not just putting my 2 cents in here, I'm betting the farm on this one. I can make like a Marine and "get in and get out" quicker and more economically in most situations than a gasser can on a "per mission vs. time" basis.

Gene

typicalaimster

Sep 30, 2005, 11:40 PM

Oh, And I can pretty well keep flying in up to and above 30 mph winds. It'll knock me around though and abuse the airframe quicker.

I'll agree with this. The first two days of flying was such abuse on the airframe. The wind would have blown my little electric plane away. I like how stable this larger craft is. I've had quite a few comments on its stability.

Myron

Sep 30, 2005, 11:42 PM

Dan,

Care to give us a close up of your tail system after you land? how about a pic or video of you carting all you gear with you and trying to get that motor tuned?

Quote "It is easier to keep the vibration down in the stills with electric. But, vibration from an internal combustion engine is easy enough to resolve once you learn a couple of things. Big gas planes have some drawbacks thats true. But your big electric twin tail boom slipstream for example gets what, 12 minutes or so of flight with good throttle management? Ouch. Thats a lot of high cost stuff for such a small return in such a big plane. When you balance the pro's and cons it's hard for me to compare the two systems"

This statement IMO is somewhat antagonistic in nature. Your barbing our large electric models under the premace that gas is better and vibration is not an issue.
"once you learn a couple of things"..

I think its best that we call the barbing a draw based on the fact that IC vibrates and poly's are pricey. These are the two main factors/differences or pros and cons however you want to look at it...

Lets compare facts...

So how big is the tank in your model?.. 20oz? how long can you fly on 1 tank? The motor is a Fuji BT32 right?.. How much does it weigh 3.7 lbs? how many watts does it put out? 1700MAX! What is max payload of this model? How often do you have to fly all day for an AP job?.. I think its safe to say that for the average (non military) job you only need to be in the air for a MAX of a few hours a day...

Fuji BT 32.. 299.00... 3.7 lbs....1700 watts
AXI 53xx 219.00... 1.1x lbs...1494 watts

If your using such a small camera, why use such a large model that requires so much effort to get off the ground?

30 MPH is NO PROBLEM for our Slipstream...

Myron

kd7ost

Oct 01, 2005, 01:21 AM

Gene and Myron,

I started this thread so guys who have preferences and ideas about the differences in a specific powered platform can air them out. I don't like gas because.... I like electric because........A combination is better because.....

Myron, the antagonism came from you who knew specific details about what I did while I was trying to openly share what I was working through, and where I was at with Gene so we could advance a proprietary business project. Gene evidently thought the information I shared with him while I was being open and honest with him was OK to let you in on, and permit you to post it in a public forum. You then used that privileged information to help argue your point. My vibration, My O'scope, I had trouble getting the digital camera stilled. That wasn't for public knowledge any more than me posting pictures of the gas plane you guys sent me would be. That’s no good sir. My antagonism was really a defensive posture. If you're going to dish it out.... well you know the rest. This thread is not about you or me or Gene or Aerial photography or anything else we all said we would keep to ourselves.

Gene, I have no argument at all with your reasoning in the mission you describe. None at all. However I'm not commenting here, nor did I start this thread to relate to what you and I talked about in any private business sense. I'm talking about flying UAV's here and not aerial photography. This is the UAV area. I have visions of having a voice repeater on station over Search and Rescue area's or other emergency situations where getting up and down and gone in 20 minutes isn't the game plan.

Let’s keep the private business we discussed out of here. You both have my email address if you need to cover that.

Electric is cool and has a place. I know it's your strength. I hope to learn more and fly it more in certain applications.

The little camera is a technology demonstration. It's nice to know I can load in the professional camera and it will all be OK though. And it will weigh more than my 5mp wide angle Fuji finepix E510 so won't have to add in the inertia.

You guys build very mission specific. That’s OK by me. I learned that early on. I build with versatility to adjust to different cargos as needed. I would rather have extra space on board than not enough for my applications. That’s OK by me too.

My platform cannot compete with yours in all areas. That goes both ways. I could put one of your wings inside my plane and my plane wouldn't even know it was there during the flight. I'm not here to compare that. I have no trouble with electric. I simply don’t think it’s an end all to AP and certainly not UAV's.

Myron, Gas engines are not like glow engines. How many times do you have to screw with your lawnmower or gas weed eater when you use those? Once a season? Never? That’s about it. If you're screwing with a RC gasoline engine all the time you either don't know what you're doing or something is not working right. And gas fuel residue isn't like glow fuel residue. Again, look at your two stroke lawnmower. It doesn't blubber out unburned synthetic and castor oil lube.

Minus the outer wing panels which plug in, I put the whole plane in the back of my vehicle. It takes me about 10 minutes to be ready to fly. That’s putting in the fuel too. The fuel tank sits under the aircraft center of lift under the wing. There is no trim change throughout the flight. I can't beat you guys there I know. You can also use a small car. I need a mini van with rear seats out at the very least.

My plane can fly autonomously via GPS for 60 miles if I so chose. (I can open that up by plumbing in another tank). Not too good yet. It will also hold altitude using BP. It will return to me if I get interference or in many catastrophic failure scenarios. You see, we can't compare these two platforms to each other. They aren't in the same class of planes. You got a T38. I got a C130. It's all good.

Dan

kd7ost

Oct 01, 2005, 01:50 AM

Geez Dan, I don't know how you guys fly in such a confined space. Must be tough. ;) I can't wait until I save up enough pennies to leave the city and head back out to the country - even though I just got to the "big" city from the country two months ago. :rolleyes: Luke

You aren't in Kansas anymore eh? Yep, we like to push the envelope out here with our huge crowds just to see everyone panick.

My preference really is for electric power for a whole host of reasons: torque, noise, no-slime, finer control, etc... Maybe also I was turned off as a kid by fiddling with those :censored: Cox engines for hours on end, trying to get them to run. Though I will say the smell of fuel really does take me back to that excited kid feeling...Luke

I remember the cox PT19 with the .049 for Christmas. I remember freezing fingers from glow fuel and.. well... it was freezing outside. I remember the "Thwack" of the prop on the finges because I didn't move quick enough. Ah, fond beginnings.

I haven't built my UAV airframe yet as I'm doing the avionics first, but I think when I do it will probably have to be gas. My goal is long distance, about 2,500 miles, and although I have pie-in-the-sky dreams of doing it electric, I just don't think it's going to be feasible for a price I can afford.Luke

Holly smokes. 2,500 miles is ambitious. I hope you pull it off. Let me know if you need a builder.

But talking about people who see the benefits of both, an argument can certainly be made for a hybrid vehicle much like we have with cars now. The technology for hobby use isn't quite nearly as good yet, but especially for long distance I think that will become a more and more attractive option. Luke

It will be neat to see what technology trickles down once it's more available at the top.

Dan

kd7ost

Oct 01, 2005, 04:09 AM

I'm not carrying a quart of flammable liquid that could torch if there is a crash. Gene

Gas won't spontaneously combust when exposed to air. Lithium Ion and Lithium Polymer chemistry does.

Dan

typicalaimster

Oct 01, 2005, 04:50 AM

I'm not carrying a quart of flammable liquid that could torch my already parched corn/wheat/barley field if there is a crash.

I've been around models since I was born. In that 28 years I have NEVER seen a glow powered plane catch on fire after a crash.

starcad

Oct 01, 2005, 09:46 AM

Glow starter attached flip the prop to prime and fire! Yes it can happen even with lower nitro fuels. On the other hand a short, or the wrong contact to a lipo and there again fire. Either way you have hazzards in both gas and electric bringing the disscussion to a mout point. Most UAV's are designed mission specific and that probably will not change to much. There in brings up the point "Why not design for mutipule missions", requires a little more though. Both the large gas and the small electric have there place and both have there pros and cons.

Myron

Oct 01, 2005, 10:16 AM

Dan

I mereley took the first defensive posture when I perceived that you were attacking the electic nature of one of our aircraft.. If you would have read closely the 12 minute flight was on a grossely underpowered expirament.. (13 lbs model, 6 oz motor) with a 11.1 volt pack... Then you commented on the Slipstream thinking it was the model that was the expirament. This is where the whole thing started to go downhill fast.. I also beleive that you openly discussed vibration problems on this site in a different thread. If you will also look at the first long post I made here.. It was NOT AT ALL directed at your aircraft and there were plenty disclaimers in there to indicate these were my opinions... I never attacked your aircraft... yet shortly after you attacked the Slipstream....

I am willing to offer the olive branch and call it a draw based on mis-understanding. There is no good reason to let this one go down like some of the other threads that we all know and love..

Deal?

Myron

CenTexFlyer

Oct 01, 2005, 10:25 AM

Gas won't spontaneously combust when exposed to air. Lithium Ion and Lithium Polymer chemistry does.

I've been around models since I was born. In that 28 years I have NEVER seen a glow powered plane catch on fire after a crash.

You know that and I know that. You guys seem to have missed the point I was trying to make. This forum is "Gas vs. Electric" and you have to look at the perception the unwashed masses will have concerning your UAS. Applicability for a particular airframe goes well beyond the cargo it can carry or the distance it can fly or who controls it. Now if you change the forum to "Cargo Capacity & Duration : Gas vs. Electric" we'd be talking apples and apples. I guess my FOV was bit broader :)

As for "private" issues, I was unaware that any were exposed that hadn't already been publicly discussed. Materials to damp vibration and the tools used are many and if you have them at your disposal give you quantitative data. I apologize if your perception is we exposed something of that nature.

Gene

kd7ost

Oct 01, 2005, 11:01 AM

Sounds good to me. We certainly see different starting points where it went down hill and read differently into what has been posted now or on different threads. It's all splitting hairs though to try and say what I meant was this and that and what I heard from you was ... and on and on. Thanks to all. I can and will let it go. Lets move on.

Dan

CenTexFlyer

Oct 01, 2005, 12:31 PM

So with that said......

Vibration is the primary issue with gas and it can be dealt with. For cargo + duration, it's gotta be gas - there is no contest. At least for the time being.

For "guerilla UA" in a confined area with light payload, get in and get out - electric - hands down.

This is strictly from a propulsion system standpoint. I can make ANYTHING fly with just about ANY propulsion system, but what you want it to do when it gets in the air is a whole 'nother subject.

Gene

kd7ost

Oct 01, 2005, 12:46 PM

I agree with all those statements. Sounds like this won't be much of a debate after all. ;)

Dan

JettPilot

Oct 01, 2005, 01:05 PM

This forum is "Gas vs. Electric" and you have to look at the perception the unwashed masses will have concerning your UAS.
Gene

If you are worried about public perception, then you would not be flying UAV's at all, you would be playing soccor. The public does not like UAV's, gas or electric, they will be afraid of either one. :eek: Luckily, I dont have build a UAV to impress a bunch of public idiots, nor do I care what they think :censored: In the end, weather I fly a gas or electric UAV is going to have ZERO effect on what laws are passed concerning them. And BTW, LIPOS catch on fire MUCH more often than gas does, due to crashes, charging, over discharging, in all phases of flight. If you are worried about fire, then gas is 100 times safer than electric ;)

As far as "messing with a gas engine" We are not talking glow powered .049's here, we are talking GAS engines that you set once and basically never have to touch again. How ofetn do you see people adjusting the mixture on their weedeaters that they use every weekend, never right ???? Its time to get over the emotional " I was traumatized as a child with a .049 story " and look at todays reality with gas engines. The electric guys spend a hundred times the amount of time chargning, recharging, balancing, and maintaining thier their packs than I do filling the tank on my gas engine and flying :p

So in the end most of you miss the point entirely. I can easily fly my 20 pound UAV an hour at a time, all day long with a 400 dollar gas engine, no mess, no fiddling, no charging, no fires, and no vibration problems.

Some have managed to get a 15 pound UAV off the ground for for 20 minutes having to be very "careful" with the throttle, have spent big bucks doing it, and then have to wait who knows how long to recharge and mess with batteries :mad: Talk about having to constantly mess with your power plant, electric guys are constantly spending time at the feild messing with batteries instead of flying :mad: The electric guys will also be spending big bucks again next year as they replace thier LIPOS have gotten weak :( I have not seen any post here where larger electric UAV's compare to gas either performance or cost wise.

I have seen some " this could be done.... " pie in the sky dreams. Bottom line is we have big UAV's right now that we need to power... No one here is NASA, and we dont have NASA budgets and technology. So when advocating a means to power our UAV's, keep in touch with reality and talk about stuff that is actually practical for us to use and afford today.

JettPilot

Myron

Oct 01, 2005, 01:12 PM

Great..

Its too bad some of the other debates cant be handled this way!... I think one of the most interesting points brought up is the whole hybrid aspect.. If you could take an IC engine and run a small light generator to Li-poly charge system and a bank of poly batteries you could get quite a bit more flight time.. Use a switching mechanism to switch between the two. An airframe similar to the Cessna O2 would be ideal....Also if you could wire in a small wind turbine type generator that could easily power some of todays telemetry gear and maybe even throw on a few solar panels to augment the RX batteries.. I could build the plane, but I am not a wire head to make the rest of it work!

Myron

kd7ost

Oct 01, 2005, 01:45 PM

I would also pass along that I use several technologies in one plane. Obviously you guys know my plane is a little large, 102 inch wingspan, 87 inches long and 22 pounds, and is flown with a Fuji BT32A two stroke gasoline engine.

But I use Nimh batteries for my flight systems. They outperform Nicds and can be really fast charged. They don't suffer memory effect so you can keep peaking them. Nicds have their place but not in my plane.

I use a couple of LiIon packs though too. First is a single cell 3.7 vdc 1400mah, feeding a 3.3vdc fixed LDO regulator and feeding my garmin geko GPS unit. This little battery powers the geko for close to 20 hours without needing a recharge. I'm also using a 3 cell LiIon pack at 1400mah to run my video downlink. It runs the 12vdc camera, GPS overlay board, 2.4ghz transmitter and microphone.

The LiIon's were purchased from a surplus source, (Like these ones but a sold out version) http://www.allelectronics.com/cgi-bin/category.cgi?category=160&item=LBAT-43T&type=store.
The Lithiums have a much higher energy to weight ratio than other types of cells. I have several made up for the downlink because they only last about 2.5 hours each and take several hours to recharge with my Maha charger. Thats my shortest lived battery pack in the plane. I could put several in the plane in parallel to resolve that though.

Here's another cool thing about the battery choices. The LiIon's continue to pack a whallop when it freezes outside. NiMh cells do too. Nicds and alkalines don't work well at all around freezing and below. They shut down till they warm back up. I fly in the winter when it's below freezing and you can't afford to have power systems freezing up on you. AAA Lithium cells don't exist so you can't run the geko off of internal batteries when it's that cold.

So even in a gas plane with no generator, I use various battery chemistry technologies to get the best performance and duration.

Dan

CenTexFlyer

Oct 01, 2005, 03:02 PM

If you are worried about public perception, then you would not be flying UAV's at all, you would be playing soccor. The public does not like UAV's, gas or electric, they will be afraid of either one. :eek: Luckily, I dont have build a UAV to impress a bunch of public idiots, nor do I care what they think :censored:

Good marketing approach....... ;)

JettPilot

Oct 01, 2005, 03:29 PM

Good marketing approach....... ;)

If had to make my living as a salesmean, I would proabably starve to death ;)

typicalaimster

Oct 01, 2005, 03:34 PM

I'm also using a 2100 Lipo pack to feed all my electrics. Their nice to use since they hold such a large capacity for such a long time. Right now the problem is my transmitter battery! That runs down before my planes run down.

kd7ost

Oct 01, 2005, 03:42 PM

Right now the problem is my transmitter battery! That runs down before my planes run down.

That's why you need to put in the autonomous parts with a failsafe style of receiver. You can get to altitude then just turn off the transmitter to save its power. ;)

Actually I put in a 1600mah Nimh AA pack from Tower Hobbies. I also keep the stock Nicd pack charged and in the transmitter case. In an emergency I can have the plane loiter overhead while I swap out the pack. The Futaba transmitter I use has the plug right inside the battery compartment. It makes it really easy to swap out. Some styles have the plug burried somewhere that you have to use hemostats or needle nose pliers to get to.

With a dual charger that can operate off 12 vdc I can field charge those NiMh's real fast too. Man, The more I think about it, the more I realize why I'm broke anyway. I got a lot of stuff but it's still never enough. :D

Dan

LukeZ

Oct 01, 2005, 03:44 PM

In fact then it really would be fair to say that everyone is already using BOTH, regardless of their position on the question. The issue is just how much of one or the other. ;)

Luke

JettPilot

Oct 01, 2005, 07:46 PM

In fact then it really would be fair to say that everyone is already using BOTH, regardless of their position on the question. The issue is just how much of one or the other. ;)

Luke

Not at all. Its pretty clear the topic here is electric versus gas engine to fly the airplane with.

We are not talking about gas powered radios, nor has this even ever been an issue... Get real...

That having been said, I do not have any electric powered UAV's or airplanes. I like big airplanes and electric is just not practical for big airplanes yet. (it can be done with great limitations and great expense, but that does NOT mean its pracitcal.... )

Given the facts presented here, and all over the electric forums... Bottom line is that electric is great for very small planes, but electric its not practical and does not give as great an endurance as gas does for big planes....

typicalaimster

Oct 01, 2005, 08:31 PM

Bottom line is that electric is great for very small planes, but electric its not practical and does not give as great an endurance as gas does for big planes....

Actaully after playing with Motocalc a bit. I can find a very simple AXI / Lipo combination that will be equal to power and durration.

JettPilot

Oct 01, 2005, 08:50 PM

Actaully after playing with Motocalc a bit. I can find a very simple AXI / Lipo combination that will be equal to power and durration.

Ok, lets hear it... The electric motor is easy, thats obvious... So lets hear what size pack of LIPO it takes to equal my G-45 in power output for an hour, or even Dan's Fuji 32.... Now multiply that by several hours we fly in a day... And how many thousands of dollars each year to buy and replace LIPOS as they get weak ???

You seem to be missing the difference between "can be done" and "practical".

CenTexFlyer

Oct 01, 2005, 10:06 PM

You seem to be missing the difference between "can be done" and "practical".

Jett..... back atcha! Come bring your big Z45 out to my ranch and take it off on the rutted logging road that turns left in 60 feet between the 100 foot pines. You ain't gonna do it! It just isn't practical. Sure you can probably find a road several miles away to get set up on so you can make your 100 foot take off roll, then get to altitude and come find my location, then return and land with your 200 foot roll out. But I've already been up, flown the mission and collected my data, got down, packed up and down the road....... before you have even reached the target zone!

So there's a "can be done" and "practical" for you.....

typicalaimster

Oct 01, 2005, 11:02 PM

Well even with the gas side let's look at the current practical applications. Alot of UAV's out there use some sort of launcher. This gets people out of the parking lot. As far as recovery... Most current things just 'crash'.

Myron

Oct 02, 2005, 08:59 PM

Hey guys,

I think it REALLy depends on the mission parameters... I wouldnt use a monkey wrench on a swiss watch nor would I try to move a mountain with a wheel barrow.
If you look at the actual watts to prop and the weigh of the motor alone.. I feel electric is the winner... There is a write up in last months RC Flyer about an Eindecker that was flow with a G26 and an AXI 41xx-xx motor.. The flying characteristics were near identical on a 17lb model and it was flown with heavy and cheap nimhs ,yes nimhs that you can have enough packs to fly all day without breaking the bank. I agree with Jett(and pretty much everyone else) that Poly's the aquilles heel of very large models...
My preferance for sub 1 hour flights with up to say that 17 lb model, I would do it with electric. It doesnt matter how many flights because I would have enough packs for that mission...

I was a die hard gas/glow guy for the first 22 years of my modeling hobby... Since my local club was way overcrowded and very kid UNFRIENDLY, I was forced to find an alternative to flying my big IC stuff... I tried a small AXI motor and a parkflyer that I could fly anywhere.. That is all it took for me to go deepside into electric.. I Can see that this topic is heavyly debated anywhere you go... Having been on both sides I encourage the die hard gassers to give it a try.. YES it is pricey to "try" but once you get your feet wet it is really alot of fun and the pros quicly start to outweigh the cons.

Jett: take a look at the specs...

AXI 5330/18

For up to 32 Nicad/NiMH cells or 10 Lithium Polymer cells, 19x12 to 20x13 props.

Examples of output for 533018:

Cell
Count Prop RPM Current Watts
to prop
10S LiPo 19x12 6250 79.0A 1941
10S LiPo 20x11 6080 84.0A 1999
10S LiPo 20x13 5780 91.0A 2088

G45:
ZEN G45 Engine 2.8 ci G45, Zenoah ADD IN STOCK
Prices With * Include Ground Freight (48 States).

Warbirders, take note! The G-45 has long been considered the premium choice for 20-26 lb, 80-85 inch Jugs, Spits, Bearcats, and similar replicas of the past.

Turning a 20 x 10 prop at around 7200 rpm, the 2.75 cubic inch G-45 provides the speed and sound for that "just right" scale appeal.

Naturally, its reputation for flawless reliability has helped make it a popular choice among modelers who might put a year into building a detailing their craft. To these modelers, having an engine that's happily thumping away at the mission's end is a paramount importance.

While the provided muffler is perfectly suited for sport or radial cowl situations, in-line engine installations are best served with manifolds available from J-Tec, Bisson or Bennet

There isnt much difference in the size of the prop and RPM.. But look at the overall weight.. For your average 15 minute "sport" flight you gonna come out much lighter with the AXI...

Myron

JettPilot

Oct 02, 2005, 10:05 PM

Hi Myron,

Very good information you have there. I do look foward to the day when I can get a big brushless motor and have enough packs to make it fly as much as I do in a day :) I agree that NIMH is probably a better choice for very lage models than LIPO... Do you know where to get 3000 maH NIMH cells cheap ??? I need to make some more packs...

As far as hand launching, all I need to do is find an olympic class javlin thrower and im all set :p The landing in the forrest I have not worked out yet :confused:

Myron

Oct 03, 2005, 10:42 AM

Hey Guys,

Its interesting to note that when AXI started it advertising campaign comparing E to glow they chose a motor similar in weight.. They were comparing a .45 Glow and the 41xx-xx motor because both would fit in the palm of your hand.. I think they were also using an 11.1 volt 4000 Mah pack... In actual testing and watts to prop and thrust the AXI outperformed the Glow motor... It was lighter than the Glow with a full tank and just a bit heavier after the glow motor ran out of fuel and flight times were similar... Now the good part.. that same AXI motor on 10S pack (yes expensive lipo) it will easily fly a 17 Lb model.. I think the versatility of E is one of its best virtues.. I also beleive that it wont be long before Lipo's really start dropping in price... The Key driving factor is that the advancing discharge rates forces the 8-12C units way down.. Also a key is the fact that you can fly a large model on a relatively low amp draw.. The heaviest plane I have flown with E power was between 15 and 16 lbs and that was at less than 40 AMPS..

Myron

kd7ost

Oct 03, 2005, 12:04 PM

kd7ost

Oct 03, 2005, 12:21 PM

I don't recall where I read it but I've heard rumblings of a new battery chemistry technology. Remember when Nicds were the only rechargeable cells. You paid through the nose for them. NiMh came along and the Nicds dropped in price. NiMh made some C improvements and then they were the real high cost cell. Double the current supply over nicds cost 4 times the amount. Each type of chemistry continued to evolve though. Manufacturers had chemists and engineers tweeking them to make them stronger, faster etc. When Lipo technology came along it was novel at first but quickly improved so you could get current in and out fast enough to run powerful motors with. The efficiency of brushless motors and switching speed controlers made it easier for any battery technology to perform better at lower current consumption levels. The NiMh cost came in line with Nicd cost. But I don't think the Lipo's as the power cell of choice will drop much in price as long as consumer supply and demand stays high and no one has flooded the market. (Like barrels of oil.) However, if some new fangled chemistry comes along that boasts better power to weight and density ratio's than the Lipo's, I would expect they would soon drop in price for the consumer and more closely match the cost of the other previously developed technologies.

Dan

typicalaimster

Oct 03, 2005, 01:01 PM

Myron,
When you use the electric (brushless) motors in a pusher configuration, what do you use for a prop? I mean, can you use the motor running backwards to keep using standard tractor props or do you have to run it one direction and go to a pusher prop?

Dan,
That's actually what I was doing. I flipped the prop around so it was pushing in 'tractor' mode. Brushless motors do not have brushes so you can spin them in any direction. So you no longer have tht flaw with the older brushed motors spinning the wrong direction and causing premature brush wear.

--S

typicalaimster

Oct 03, 2005, 01:05 PM

I don't recall where I read it but I've heard rumblings of a new battery chemistry technology.

Right now I believe we're up to Gen 3 of Lipos. I'm sure someone will correct me here. As newer generation LiPos come out, the cost of the older ones goes down. There is a big push not only from the model industry, but also the computer and cell phone industry as well. People want to be able to use their laptops for 12 hours, or talk on their phones for 2 days.

Myron

Oct 03, 2005, 03:33 PM

Hey Dan,

You are correct.. Electric brushless motors a actually AC and 3 Phase.. Changing the rotational direction to suit your needs is as easy as switching any two of the three wires.. You no longer have to worry about pusher or tractor props.. Another advantage is the prop technology.. E props are much lighter and thinner than their IC counterparts... I dont think they look as cool though!

Myron

kd7ost

Oct 03, 2005, 04:16 PM

OK,

So if I'm in the market for a motor that will fly a 5 to 6 pound plane, what are my options? Good and bad. Brushless only. With or without gear boxes. What are the different brands that are decent motors?

Thanks in advance

Dan

edited to include

Actually, I think I'll just get the AXI 2820/10 with 40 amp speed controller and radial mount. It looks like just what I need. Any sources for those cheaper than Hobby Lobby?

Dan

LukeZ

Oct 03, 2005, 05:01 PM

Ahh, Dan. You're crossing over to the dark side now...

kd7ost

Oct 03, 2005, 05:32 PM

Damn Luke, Leave me alone. ;)

Actually I've argued all along that there's room in my stable for both styles of platforms. You've seen where I fly so I'm sure most guys can see the validity of larger gasoline powered platforms out here. Runways? Every road is one. I got more runways than you can shake a stick at in most locations. But I have a couple of Huge grass parks near by where I live. I can't fly there unless I get something smaller and quieter. (I got something up my sleeve)

I'm actually looking more at the AXI 2820/12 now. Exact same cost, fairly comparable battery requirements but operates with a little less power consumed. I can get better endurance out of it with a smaller prop. That will fit a little better with my new project. I'll give some off the top end as my new platform isn't going to be a fast one anyway. More power won't speed it up. It would just drain the batteries faster.

I'm not hearing any arguments about the AXI yet. Those things look like Brick outhouses. Not the can type motors. I've found some cheaper brushless motors but these things are pretty solid looking. That radial mount is slick too.

(There goes my big new Zenoah :( )

Dan

Myron

Oct 03, 2005, 05:56 PM

Dan,

I have run AXI, Mega, Jeti, and Eflight both direct drive and geared.. You definately want to go direct drive!.. Geared is good for the real small stuff or the real big stuff.. For mid range size go for the AXI line.. If your 5-6 Lb model needs to be a 3D type go with the 4130-12 on say 14-18 volts.. If you want more of a leasure type bird the AXI 2826-12 would be a good choice.. I have one of these and it will swing a 14x10 prop at 5500 RPM at 38 AMPS on 11.1 volts. Any .40 size trainer would fly great on this motor and it will have plenty of power on a single 5000 Mah pack... For your notes, a 5000 Mah pack weighs 11 oz.. the motor weighs 6.6 oz.. the ESC is about an ounce... Making this leap you will gasp at first when you add it up BUT once you fly it a few times you will be looking to buy a few more packs so you can run for hours...

Do some research on Hobby-Lobby's site and when you decide let me know. I can probabaly get you a few bucks off their price...

I would like to offer this advice.. when shopping for your ESC, consider spending the big money on that part... they are all downward compatible with all the motors and the weight difference between a 25 AMP and a 77 AMP is less than an ounce. I have 25's, 35's, 40's and 45's... for the money I should have just purchased 2 of the Jeti 77 AMP Opto+.. This ESC will fly anything you want up to probabaly a 20 LB model...

BTW: I am just starting a new 90" Wing that I will use this motor on.. If you are hesitant on spending the money up front, I have a Mega 45-3 and a 30-3 that I may be willing to let you try out.. Look at the specs on HL to see what it says and see what you think may be the best option to try out..

Myron

kd7ost

Oct 03, 2005, 06:26 PM

Myron,

It looks like that’s a higher torque motor (2826/12) and for bigger props and they allow almost double the cell count (voltage) from the 2820/12. Efficiency looks about the same but at the cost of a higher voltage. I'm going to be making a smaller plane and would rather not have the high cell count and don't want to have to swing a prop that big. For what it's worth on their site they rate the 2820/12 for larger planes than they do the 2826/12. I'm not really looking for mongo power. I want enough power to get to altitude but then would like to throttle back and loiter longer. I know a big prop turning slow is better than a small prop turning fast, but this project won’t be a plane that is all that big. I’m thinking it will be in the 4 to 5 pound range. The 2820 line should work out as an upper size for that weight I’m thinking. I don’t mind having a little more motor than I need but I don’t want to go real big. Also, if I have the space for double the cell count, I would rather put them in parallel with the other pack to double the duration. Can you see any holes in my reasoning that I'm not thinking of? You’ve had good luck with the AXI motor’s then? Are they as solid as the pictures make them look?

Dan

kd7ost

Oct 03, 2005, 06:30 PM

Oh,

And do you use the Radial mount with that prop adapter AXI has? It looks like an easy way to keep your motor in front of the firewall so you don't have to vent the heck out of it (firewall) for cooling. Just the wires need to pass through. A vented cowl could then be added to help protect it and keep it somewhat clean.

Myron

Oct 03, 2005, 06:56 PM

Hey Dan,

No holes!.. The good thing about the AXI motors is the flexibility.. When I was running the 2826-12, that was on 11.1 volts.. Yes you can increase cell count for more power. With the AXI line the last 2 numbers are for how many winds the motor has.. the less winds the more RPM per volt swinging a smaller prop, the higher the # of winds is for less RPM but more torque.. I havnt looked at the 2820 just yet... HL has pretty good info on their site when it comes to choosing the best E power system for your model.... Yes, get the radial mount, it makes things easier!

Myron

typicalaimster

Oct 03, 2005, 11:40 PM

I would personally go with a 2826. The 2814 is what I was using to fly my little bird around. I was looking at the 2826 and a 4000 mah pack for my bigger bird. I had a 2820 and its less efficent according to their specs. I didn't get a good test since I haven't invested in a watt meter. I couldn't figure out a good prop/battery combo. I gave the 2820 to my dad and he's going to give it a whirl with a 10x6 or bigger prop and a 3000 mah pack.

typicalaimster

Oct 03, 2005, 11:49 PM

I would like to offer this advice.. when shopping for your ESC, consider spending the big money on that part... they are all downward compatible with all the motors and the weight difference between a 25 AMP and a 77 AMP is less than an ounce.

The guy at my hobby shop always hooks me up with a speed controller that will shut down before frying my motor. I figured it's safer to shut down on that bleeding edge than frying a $100 motor. Some of these motors say you can run X seconds at Y watts before you become a smoke bomb.

kd7ost

Oct 04, 2005, 12:02 AM

I looked that over pretty well. I agree except for one thing. It just takes a lot more cells for those new big magnet torque monsters to become their most effecient. Up to 5 Lipo's or up to 12 to 14 NiMh or Nicd cells to hit them with their full rated electromotive force. Dropping the cell count drops the efficiency. Thats with the 2826/12. The lower winding versions are hotter and faster and consume higher rates of current.

I do see that the 2826 series are new and have more power. But it takes more cells to operate with the stronger magnets. That means more cost and less cargo space. Is this a deminishing return when you're trying to build a sub 6 (really sub 5) pound plane? Thats a huge cost and power cell difference. Then you have you're charger ability. It's easier and cheaper to get a charger that will field charge 3 LiPo's than 5 Lipo's.

I'm still wanting arguments both ways. I'm going to commit to this purchase by wed.

Dan

CenTexFlyer

Oct 04, 2005, 08:32 AM

Is this a deminishing return when you're trying to build a sub 6 (really sub 5) pound plane?

Depends..... what is your airframe : cargo ratio?

Jim T. Graham

Oct 04, 2005, 09:18 AM

For a 5 to 6 pound plane that is not for 3D the 2826 is as small as you will want to go. I have flown the 4120 and 4130 pretty extensively. I always opt for low winds, you get more power from fewer batteries. The 4120 low wind is almost the same power as a .40 to .46 size two stroke. I flew the 4130 on a 4.6 pound 3D plane and it was close to .90 size two stroke power.
I flew electric 5 pound planes exclusively for the last 2 years. I recently pulled all of my glow planes out (the same kind) and gave glow a try again. I have to admit that the ability to just fill up a fuel tank with glow fuel and get back into the air immediately is great. I really missed the ability to fly again as soon I landed. I also think I was "babying" my electric planes. I knew if I went full throttle with my E powered planes I ran the risk of really cuttting down my flight time. With the glow motor I could fly as hard as I wanted from start to finish.
The benefits of E flight are obvious but now that I'm back on the glow fuel I see the benefits there as well.

kd7ost

Oct 04, 2005, 10:22 AM

It is to be a rogallo wing with up to a few pounds of cargo.

I would like to fly longer than a few minutes and I simply don't have hundreds to invest in battery packs to do it with mongo 3D power. I'm an endurance, fly it on the wing not on the prop kinda builder. The rogallo wing is very draggy so giving it more power isn't going to make it go faster. It's terminal velocity will be quite slow. I need to balance the endurance aspect. Naturally, lighter is better and I'm listing the weights as upper extreme's. If I only put a digital camera and a downlink with it's battery power, I should make 4 pounds easy. I plan on putting in a pico pilot.

Dan

RedlineUSA

Oct 04, 2005, 12:51 PM

Hey guys...

Thought you might like to know... We have some very high performance Lithium Polymer batteries coming out in about a month. They are capable of providing 15 or 20 C continuous current depending on the cell. We currently offer them in sizes up to 18.5V and 6000mAh, but we can provide larger configurations if you need them.

The prices are very reasonable.

(@ 15C, a 6000mAh pack would provide 90 Amps continuous current with bursts up to 120+ Amps)

Myron

Oct 04, 2005, 01:36 PM

Hey Dan,

The good thing about that 2826 is that you have the option of adding cells beyond the standard 11.1 volts for more power if you NEED to.. Trust me on this one. go with the 2826-12.. It runs great on a 3 cell pack with anything from a 10-6 to a 14-10. The Rogallo is very "draggy" and your gonna want a lot thrust/volume of air from a larger diameter low RPM prop... When I had my Seagul Telemetry System in my first expiramental TBP plane that little 6.3 oz motor flew 13 lbs at 38 AMPs. I dont have the formulas handy, but it would swing that 14x10 at 5500 RPM and move alot of air.... This I do beleive was at the outer limits of the motor on 11.1 volts, however your only looking to fly 5-6 Lbs.. If you go with the 2820 your limiting yourself to a 11.1 volt system.. What happens if decide you do want to carry your full size camera on a gimballed mount?.. With the 2826 you can do it.. With the 2820 your pushing your luck.. The weight savings is neglible between the two, but the aircraft size range is way better with the slightly larger motor...

Myron

kd7ost

Oct 04, 2005, 02:11 PM

kd7ost

Oct 04, 2005, 03:05 PM

Hey Dan,

If you go with the 2820 your limiting yourself to a 11.1 volt system.. What happens if decide you do want to carry your full size camera on a gimballed mount?.. With the 2826 you can do it.. With the 2820 your pushing your luck.. The weight savings is neglible between the two, but the aircraft size range is way better with the slightly larger motor...
Myron

All good points Myron and thanks for keeping plugging away. I may end up going that route for the reason you state but will likely never know what the best motor of the two for my application is. The size range of the aircraft isn't as important to me as duration range. Simply put, Given an 11.1 vdc pack of 2000 mah, which of the two motors will fly my craft for a longer time? I'm confident either will fly the plane and the 2826 will have more power. Niether one of them will cause high speed in a rogallo. (Heck rocket assist won't help a rogallo go fast. But thats what is a good trait in some applications) So the extra power would only be for heavier lifting if I need to. Heavier lifting is secondary to light lifting and longer run times in this new build for me though. The question most simply stated is, will the 2826 give longer run times on the same battery pack than the 2820 will? Or will the 2820 give longer run times? Lets leave out the being flexible part and say with a 5 pound rogallo period.

Dan

Myron

Oct 04, 2005, 04:44 PM

I hear you.. I think that if your planning on running a small pack(2000maH) you will not be satisfied with either motor! Or maybe you would be for about 12 minutes. Mind you this is all based on AMP draw.. Say you have a 2000 Mah 10C pack(This pack is most common for 2-3 lb park/sport models).. The most your gonna be able to SAFELY pull from it is 20 AMPS maybe a few more for a short burst... That is not going to get you where you need to be.. Go for a 4K-5K Mah pack.... they weigh 10-11oz each so your at about 17 oz total for a power system good for 20+ minutes of flying.. Add a pack and double your run time. Yes your startup cost are gonna be high with Epower BUT also consider the cost of Glow Fuel at 17 bones a gallon...

For a 20 minute flight with a GLOW .40-.45 your gonna need probabaly 10oz of fuel.. you can fill your tank 12.8 times for 4.26 hours of flying at a cost of 17.00.. Lets say you fly 100 hours per year... Thats 23.47 Gallons of fuel at 17.00 is 399.00 per year in glow fuel... To fly the same amount of hours with an E platform you will spend 130.00
per 4200 Mah pack to get you your 100 hours flight time.. That is 390 dollars in big packs...

This being said: for 100 hours of flying per year

Glow: .45= 99.00
Fuel: 399.00
Tank: 5.00
plugs 10? @ 4.00 each
Starter 59.00
Glow driver 19.00
fuel pump 19.00 640.00 per year

E-Power

AXI: 282x-xx 98.00
ESC: 113.00
3 Packs 390.00
Charger 119.00 $720.00 So you loose $80 in the first year BUT you get it back and some after your second season.. And If you dont crash your packs then you get a free 3rd season!

Its about effiency and run time for you.. DO not spend tons of money on 15-20C discharge rate batteries.. Instead, take RedlineUSA up on his offer and see what he can do for you on high capcity packs of a lower discharge rate.. Keep in mind that the AXI motors whichever you choose is most efficient between 25-35 AMPS.. My guess based on size and weight of your Rogallo you will probabaly pull 18-23 AMPS cruize...

There may be a little fuzzy logic in there so correct me if i'm wrong..

Myron

kd7ost

Oct 04, 2005, 05:16 PM

Hmmm, Sounds good. I have two full cases of power master fuel so thats licked.

But, I'm not going to use it for this. To maintain versatility and allow for future expansion, I'm going to go with the AXI 2826/12 motor. This is probably closest to both worlds but will certainly be big enough to get the job done. I'll just close my eyes when I buy the batteries and charger. It's not painful if you don't see it eh? ;)

Thanks all. It's a big chunk for me and a little outside the norm for my applications. I didn't want to rush into it. I can certainly see the virtue of having weightless dragless aircraft. (Not what I'm doing this time out) Again, thanks Myron and Scott for you valuable insight.

Dan

Myron

Oct 04, 2005, 05:41 PM

No problem!

I again cant stress enough how much you need to really get familiar with the different ESC's that are out there.. BEC, non BEC and what the servo limitations are, OPTO vs non OPTO, programable via USB or hard card or the PITA "beep flash Cryptography", Hard & Soft start, BRAKE, and Timing, ect.... I was an Impulse buyer when I started E-power.. After buying alot of the wrong stuff I got real good at researching before I purchased anything...

JETI and CASTLE are the leaders of the pack... SHOP WISELY!

The tried and true charger is the Great Planes Triton... Its 119. bones but worth the money.. There are other chargers for less and some for more but you cant go wrong with it.. Be prepared to get a 12 volt power supply to run the Triton because it doesnt work off 110 AC...

Myron

kd7ost

Oct 04, 2005, 06:11 PM

They sell the motor with speed controller in a combo deal. It's a 40 amp unit but it looks like there are a few choices with those. I definately want the one with BEC and it looks like the program card is pretty dirt cheap too. It looks liek this will do the trick. Would I be going wrong with this?

http://www.hobby-lobby.com/jetiblue.htm
JESAP40W

Dan

Hovertime

Oct 04, 2005, 06:17 PM

I think one of the most interesting points brought up is the whole hybrid aspect.. If you could take an IC engine and run a small light generator to Li-poly charge system and a bank of poly batteries you could get quite a bit more flight time.. Use a switching mechanism to switch between the two.

Actually thats not practical.

Lets say you have an internal combustion engine.
You have x power needed to fly at the shaft. Then you produce and convert additional power to electric power, with associated loss and then again from electric to mechanical power, again loosing a lot.
Much better is to simply use mechanical power provided by engine. Small alternator is a good idea to recharge radio pack, for long flights only.

Ground vehicles benefit some and not too much if you calculate the difference and throw away hype. They benefit only because they reuse energy of deceleration. Hybrid vehicles use more gas on the highway (constant power usage-same as plane in cruise) than same car with just the same gasoline engine would use.

Oh - another idea floating here-especially for UAV use I would use ONLY geared motors, with as large prop as possible. That translates to efficiency. which is not something a DD motor can be proud of ;)

Hovertime

Oct 04, 2005, 06:34 PM

Regarding brushless ESC's - in my humblest opinion - Castle Creations is the best choice for many reasons, especially for USA buyers.

ElectroLawndart

Oct 05, 2005, 12:14 AM

Actually thats not practical.
Oh - another idea floating here-especially for UAV use I would use ONLY geared motors, with as large prop as possible. That translates to efficiency. which is not something a DD motor can be proud of ;)

What about an outrunner DD brushless. I was under the assumption that outrunners were more efficent at turning larger props than an inrunner and gearbox because of the losses in the gearbox. Granted most of this is through the opinions of others and not because of much direct research from me. <Bad me!>

Dart

Myron

Oct 05, 2005, 10:55 AM

Hey Dan,

Be careful if you go with a controller with a BEC.. Yeah, you save some weight, but you have to be careful how many servos you can use. You will probabaly be OK with a Rogallo because you dont have a bunch of servos in the wing.. BUT, if you decide you want to build something different down the line you may be in for another ESC or you would have to use a back up power source to run your additional servos..

Hovertime,

My thinking is somewhat old.. Similar to a WWII submarine.. Start off with large IC engine on an electric start system and have a small generator on it as well.. Launch a twin "Cessna O2" type aircraft with E power and fly until you hit LVC where you then fire the IC motor... once it is running use it to charge the Lipos.. then switch back to Epower when the batteries are charged... Yes, you will run out of gas eventually but is seems that it could be done... I know its not practical now because it takes too long to charge the Lipos, but technology, she is a changin! I was at the LHS the other day and they had some small solar panel kits that were good for .5 volts and 1200 Mah.. It was small and light.. I know nothing about solar panels but I am assuming you can serial stack them right? I may pick up a few and wire them into my next bird and use my Seagull Telemetry system to monitor their output in real life..

Myron

kd7ost

Oct 05, 2005, 11:02 AM

kd7ost

Oct 05, 2005, 11:50 AM

Geez Dan, I don't know how you guys fly in such a confined space. Must be tough.;)Luke

Luke,

Here's the other pictures Ivspark sent me. These are all in Idaho just north of the Owyhee mountains and South West of Boise. These are all pictures of my plane in flight taken from IVsparks SS in flight.

Dan

Myron

Oct 05, 2005, 12:22 PM

Hey Dan,

You should look into the "Opto" line.. They allow for a much higher voltage to power the motor. To to BEC or not to BEC?.. This is the question!.. I think the BEC's are best suited to park flyer models and ones that dont have any real amp draw from the servos.. I think with the types of models your building a 3oz RX battey is not going to make a difference.. The hardest part of this decision is what ESC to get.. Being I have been there done that and learned that its better to get more than you need over enough to get you by. On the low end you gould get a Advance 40+, BEC.. this will get you by up to 11.1 volts.... Get you by for a while the Advance 40+, OPTO..(supports higher volt systems) Never have to buy another ESC get the Advance 77 OPTO +.. If you want the bare minimum to get you by get the Castle CC35 with BEC.. this is a great BEC ESC and it is super light but your really on the edge of your performance envelope.. If you go with the Castle make sure you get the USB programmer..

Myron

icebear

Oct 05, 2005, 01:09 PM

Hey Dan,

Really nice pictures - impressive to see A2A pics of an UAV!
And I thought MY field was vast...

/Icebear

JettPilot

Oct 05, 2005, 02:12 PM

Yeah, those pictures are really incredible and beautiful :D I wish I had a place like that to fly from :(

kd7ost

Oct 05, 2005, 02:45 PM

Thanks guys,

I credit IVspark with the pictures. I have places a lot more desolate than this to fly at. I know I'm very fortunate. I promise to take advantage of it. :D

Dan

kd7ost

Oct 05, 2005, 03:45 PM

Hovertime

Oct 05, 2005, 04:20 PM

What about an outrunner DD brushless. I was under the assumption that outrunners were more efficent at turning larger props than an inrunner and gearbox because of the losses in the gearbox. Granted most of this is through the opinions of others and not because of much direct research from me. <Bad me!>

Dart
In medium size variety outrunners and geared inrunners have similar efficiency at output shaft. That said if you want most efficient plane - it will be on a slow side, and with large slow turning prop. To turn same size prop outrunner would need MUCH more power than geared motor. if it uses smaller prop - prop efficiency is lost.

If you got to large or small motors differences change, and is also different if you want fast plane such as fast wing. Fast is not the best for video use.

But both geared inrunner/outruner and DD outrunner/inrunner motors would find their optimal place in different planes and match different desires of builders:) DD is nice since there is no gearbox to maintain.

Hovertime

Oct 05, 2005, 04:31 PM

Hovertime,

My thinking is somewhat old.. Similar to a WWII submarine.. Start off with large IC engine on an electric start system and have a small generator on it as well.. Launch a twin "Cessna O2" type aircraft with E power and fly until you hit LVC where you then fire the IC motor... once it is running use it to charge the Lipos.. then switch back to Epower when the batteries are charged... Yes, you will run out of gas eventually but is seems that it could be done... I know its not practical now because it takes too long to charge the Lipos, but technology, she is a changin! I was at the LHS the other day and they had some small solar panel kits that were good for .5 volts and 1200 Mah.. It was small and light.. I know nothing about solar panels but I am assuming you can serial stack them right? I may pick up a few and wire them into my next bird and use my Seagull Telemetry system to monitor their output in real life..

Myron
Submariners did not use dual power to increase range, rather they were forced to use it since they were not able to use diesel engines while submerged.
I have described my thinking in post #67, but to summarize here it is:

You would fly much shorter distance if you convert energy 4 times (fuel -> mechanical->electrical->electrochemical->mechanical.

And you would fly much further if you convert energy just once: Fuel->mechanical.

Every conversion robs energy.

Plus there are other bad side effects such as associated weight gain, cost, complicity lower reliability .

Solar panels would provide very little power per weight/cost. Don't bother.
There was a hobby aircraft - ultralight glider with tiny components powered by Sun, barely flew on good sunshine. Cost a lot. Solar panels are not ready yet, and there is not that much solar energy "in the air";)