Author Topic: SHOCKING the Oriental (Read 25333 times)

Dennis Adamisin · « **on:** September 12, 2007, 08:43:55 PM »

OK, if I keep modifying these ARF's like this the folks at Brodak's are going to get CHEEZED! However, its like cooking; you get a little of this and some of that, you wonder how it might go together and... GOULASH!

This story starts back at this year's fly-in. I got a chance to fly John Paris' (actually Frank Carlise's) Super Clown with the Brodak electric system in it. The experience was eye-opening and a power system followed us back home. Discussions with Mike Palko indicated he was pessimistic about using the power system outside of its intended use, however, we were convinced that the power available would handle a larger, draggier bird and set-out to find a test bed. Upon further review, we came back to an Oriental. Dad had one nearly RTF, seemed
like the fastest way from there to here was to "borrow" that bird, gut it and stuff the electric power package in it.

So that's what I did. Also blunted the leading edge, shortened the flaps, and sealed the hinge lines - like the OTHER Oriental I am flying - see that post for details.

Anyhow, the key to this mod was adding a nose ring off the end of the existing engine mounts. To this some lite ply side panels were added then aggressively shaped so the cowl would fit over them. Finally, the fiberglass cowl is glued on with silicone seal, tying everything together and reinforcing it all. Purpose built this could have been
lighter and stronger. Because the cowl is glued on, the existing cut-out in the cowl (for the slimer engine) was made symmetrical and the engine installs from underneath and slips forward to the firewall.

The Brodak battery ALMOST fits perfectly in the tank compartment. If the wires came off the front instead of the side corner (or if the fuse was a tad wider), the battery would fit on the mounts where the tank normally sits. However, the web between the mounts, then the mounts themselves were removed and the battery easily fits to the top of the fuselage. Lots of room for airflow too. A hole was cut in the rear bulkhead to channel air out under the wing, and two holes cut in the top to vent heat there.

The engine controller, timer and arming switch were a bit more perplexing. Besides this is a test bed and it is better to make FUNCTIONAL installations rather than pretty ones. That's my story and I'm sticking to it. Desire was to get the controller where it would cool. The timer and arming switch pretty much have to be exposed to
power up the system. Anyhow, the ESC was siliconed into a hole cut in the tank, uh, I mean battery hatch, the timer up on the fuselage side where it can be seen and activated, and the arming switch on the side.

Several folks have posted that their best luck came with the 9x4.5E APC prop - so that's where we started. Sounds small, but historically there is precedent. Folks like Kostecky & Gierke used to use 9-6 three blades
on larger/heavier birds than the Oriental. I rationalized that their 3 bladers running around 8k-9k "filled the disc" about the same as the 9" 2-blade at the expected 12k output. My flight with the Super Clown also demonstrated that the little flatter pitched prop had a LOT of recovery in it if the bird got stalled.

Going in I was more afraid of TOO MUCH speed rather than too little. The Brodak system is purpose built and not tunable - so any tuning would have to be with props, aerodynamics, and line length. The SLimer Oriental flies on 63' lines so thats were we started.

Test flight showed lap times around 5.0 sec ON 63' LINES, with LOTS of power to do anything! Near end of run it slowed down quite a bit, and shut off on cue at 5 minutes. Opened up the fuselage and discovered the battery had ballooned! Second flight started off around 4.8 sec lap times and got (I think) a low voltage shutdown short of 5 minutes.

In an effort to slow down the bird and maybe lighten the battery load, my brother Arch the "propellor artist" tricked out the 9x4.5 by narrowing the blades substantially. Got us a couple tenths of a second lap time, so we went extreme. Flight 4 was with a stock 9x4 PowerPoint wood prop. Starting lap time was 5.3 sec - about the same as the LA40 Oriental! Then a bout 1.5 minutes into the flight the motor gave a shut down signal. Then did it again at roughly 1 minute intervals until it finally shut down at 5 minutes. Discussion with John Paris indicated he had a similar experience and determined the ESC was bad, so we got a replacement. BRODAK STANDS BEHIND THEIR PRODUCTS!

Figured we had it nailed, but subsequent flights showed the thrust was just too far off to accept, so went back to the modified APC.

My plate is full and my experience lacking, so the bird was packed up and sent home with my nephew Archie, the RC Electric pylon racer. A couple days later he calls and says all the smoke got loose from the charger! So he used his Hobbico charger. Took it out to fly, set the timer for 6 minutes and did a full pattern. Reports more than enough power & duration. Second flight like the first except he added a few extra laps here and there. He has a Triton on order and a box of alternative new props to try. The Triton will really let him see ho hard he is working the battery. Figure if we can get it flying on a 4 pitch with diameter to suit we'll pretty well have it licked. As it is, Archie reports (and I concurr) that he would not be afraid to take it to a contest.

Summing up, we are able to EFFECTIVELY fly the 47 oz bird with the stock Brodak system using a modified APC prop. If we can do some more prop tweaking I think the system will be pretty much good to go!

Archie Adamisin · « **Reply #1 on:** September 13, 2007, 08:15:41 AM »

I would first like to thank my Uncle Dennis for the opportunity and the good faith in my abilities to grab a hold of this project. I am very excited by what I have seen so far and think the sky is the limit for electric powered stunters.

After flying this system, I went home and did some severe number crunching on some spreadsheets (even made some new ones to correlate to CL use to see what the power to weight ratio was, current draw, & rpm. It seems odd to me that with as little power (wattage) as this system has, how efficient it is in delivering that power to thrust to overcome the drag of the airframe & lines. Mike Palko's formula's have been very helpful in seeing what this system or what any system is capable of delivering with some set parameters. (THEY WORK!!!!!)

The hard data collected so far is as follows for the APC 9 x 4.5 (narrow):

Static rpm = 12,800
Static current = 32 amps
Lap Speed = 5.0 SEC.
Airframe weight = 47 ozs (2.94 lbs)
line length = 63 ft.
Airspeed = 56.5 mph
Calculated thrust = 28 ozs
Static watts = 320
watts/ lb (static) = 109

My next test session will include a new modified APC to 10.5 x 4.1 narrow blade to slow the lap times to 5.4 seconds & increase the thrust to 34 ozs (calculated). The current smaller dia prop has enough thrust, but it would be nice to have more (especially when flying in the Muncie calm

). I don't like to fly fast. I set-up my stunters to fly 5.6 to 5.8 lap times. This is very different from the norm, but in my opinion gives a better corner and a sharper flight. The Oriental may not be capable of these slower speeds, but a more modern stunt design with this powersystem would be. (Like an Orange Crate or an Eclipse!!!) This powersystem would also be ideal for most classic airplanes and believe me the wheels have been turning in the Adamisin stable for some applicable designs with 550-600 sq in.

An Eagle Tree system would be very beneficial to tweak my spread sheet formulas and see the effects of a stunt flight on current, rpm, and average wattage. When I get the Triton charger and JMP timer, I am going to try one of my Kontronik 3SL40-6-18 ESC's on it so I can use governor mode to see what effect it has. That would probably be the last bit of adjustability needed to get this system where it needs to be for CLPA.

I'll post more with pictures as my results come in.

Mike, what are the design limits of the Brodak Motor, controller, & battery?

Archie Adamisin

Muncie, Indiana

Mike Palko · « **Reply #2 on:** September 13, 2007, 10:00:20 PM »

Hi Dennis & Archie,
I am VERY surprised you have gotten this far with the Brodak power system!! I almost need to see it to believe it

. It is by far the lowest watts/lb that I have heard of flying the pattern. I look forward to hearing more in the future of how things come together (or apart

). I would love to compare it to other electric ships I have flown/seen. Does it slow up hill? What are the temps after the flight? What kind of wind have you flown in?

A thought on your lipo batteries. Before your first use "break-in" your packs by charging and discharging them ~5 times at 3-5C (12-20amps). I wrote about this in the last issue of CLW. And also when you charge use a balancer, if you are not doing so already. (I apologize if this is over simplified! I know Archie flies electric already)

The Brodak power system is limited to the following:

Motor- 400watts max, 14volts max

ESC- 45amps, 4S lipo or 12 round cells (I am fairly certain the max voltage is correct)

Battery- 40amps constant, 48amps burst (10-12C discharge)

Congrats

, Mike

Archie Adamisin · « **Reply #3 on:** September 14, 2007, 05:45:38 AM »

Hello Mike,

Thanks for the specs. I am quite surprised that this system is as close as it is to working as well. I flew it yesterday in the wind (10-15 mph) and it flew with even more authority. I really noticed the speed yesterday though:o. My first flight session was in calm conditions (1-3 mph) I believe that we will outrun the abilities of the Oriental airframe before we come even close to outrunning the potential of this system.

I haven't noticed a slow down up hill, but I know that a larger dia, lower pitch prop would benefit the system greatly. I am currently working on a 10.5 x 4.1 narrow blade prop to up the current 2-3 amps and increase the thrust, but slow the pitch speed/lap times to a more reasonable 5.4 sec/lap. I don't believe the airplane will fly very well slower than that.

Battery temp is barely warm and the motor is surprisingly cool. The electrics I flew (way back when) were speed 400 pylon racers to FAI pylon F5D which the power-systems were pulling 75-125 amps on 7 to 10 NimH cells. I am used to batteries being Nuclear HOT

after a one minute 180 mph flight. I was lucky enough to represent the USA at the electric world championships in San Diego in 2000. I learned there how far behind at that time we were to the Europeans in electric model technology. The Germans (Rainier Hacker & Harold Konrath especially) are very good people, and very ahead of their game. And that was 7 years ago.

I have been flying Li-poly's in some RES sailplanes and foamy fun flies for the past 3 years. I can't believe how far they have come in such a short time. They have solved so many problems with heavy electrics. After having some charging issues with the supplied charger, I am using an Accupro quick field charger I got for my small Li-Poly's. I can only charge @ 1 amp, so it takes a while. I always use the balancer while charging. I have a Triton 2 on order so I will soon be able to charge at a more acceptable rate. Do you have any suggestions on different chargers? Have you tested different charge rates and how they effect loaded voltage and capacity? I could adjust how my F5D motors ran by changing the charge rate. If I wanted a fast first 5 laps, I would charge @ 7.0 amps, but if I needed the runtime, I would charge @ 4.5 amps. This also worked well on my speed 400 racers (my trade secret

) The discharge curve for NiCads & NimH changed drastically. From what I have seen with Li-Poly's, they have a very flat discharge curve which for stunt is perfect.

I had tested a power system 5 years ago using (2) 12 cell packs in parallel with one of my Astroflight 2t brushless 05 on a super box. Plenty of power, but it was going to very difficult to build an airframe light enough to carry 24 cells and fly competitively.

I will continue to report my findings on this system as soon as I get more props to try. I have taken some pictures of the installation and have some in-flight action shots from yesterday's session that I will post tonight.

Archie Adamisin

Muncie, Indiana

Mike Palko · « **Reply #4 on:** September 14, 2007, 04:30:58 PM »

Archie,
Great info so far. Congrats on making the USA team back in 2000! That is always something to be proud of no matter what aspect of the hobby it is.

It is true NiMH cells perform drastically different when they are hot and cold. When I flew NiMH cells in precision aerobatics it was hard to time the charge cycle to the flight order. To get the most from the cells I needed to pull them off the charger (HOT) and fly them within 5min.

There is no gain or loss when charging lipos. The majority of lipos are still charged at 1C (some of the high discharge 25C + can be charged at 2C or more "supposedly"). And lipos do have a much flatter discharge curve (to our advantage).

The best charger I know of is the Astro Flight 109. It is affordable, VERY user friendly and works great. The Thunder Power 1010C is also an excellent charger, it is costs more, is more complex, but it to works very well. There are others (Triton, Schulze), but I feel the first two are the most popular.

Mike

PS: Check the current levels in todays F5B and F5D events. CC doesn't make a 300amp ESC for nothing!!!

Dennis Adamisin · « **Reply #5 on:** September 15, 2007, 07:14:58 PM »

After putting the pieces togehter and flying, it quickly became obvious that we needed more brainpower on refining the system - thus young Arch got in the game and has taken it farther/faster than I was.

Mike:
Just how much interchangability is there in the Brodak system; can the ESC & timer be used with a different motor? Can the timer be used with a programmable ESC? & etc?

Alan Hahn · « **Reply #6 on:** September 16, 2007, 08:43:24 PM »

I couldn't get the JMP-2 timer to work with the Brodak ESC--my guess is that it wasn't being armed right. But without documentation I am not sure. Since the Brodak timer is an entry level timer (with one throttle setting---max), I went ahead anf bought a Castle Creations 35Amp Phoenix ESC. There sound like there may be better ones for CL out there now---I am not sure, but I think the next step from the E-Super Clown requires at minimum a ESC and timer change. I have been running the Brodak Motor on the Castle Creations ESC and JMP2 timer.

Archie Adamisin · « **Reply #7 on:** September 17, 2007, 07:47:02 AM »

Alan,

Thanks for sharing the info on the Brokak controller. I just got a JMP-2 timer and was going to try it out to see if I could get a handle on the lap speed. I did do some initial set-up/playing with the timer last night and found it to be very user friendly and very flexible. I can't get over the size of this thing and what it does. Very deceiving @ first glance. It did successfully arm my Kontronik 3SL40-6-18 controller, so I will go that route in my next trials this week. The Kontronik controller has governor mode so it will be interesting to see what affect it has on the system. I am concerned about running the @ partial throttle setting for an extended time though because I have had bad experiences with this in the past creating excess heat and letting out the factory smoke. But I am going to try it @ see what happens.

As a side note question, running more than 3 cells disables the BEC in all the controllers I have seen. Is everybody running reciever packs in their (4) & (5) cell set-ups? If so, what size cells? My Kontronik controllers don't have BEC, so I will have to run a rx pack which is easy to do with the JMP timer. Any thoughts??

Archie Adamisin
Muncie, Indiana

Alan Hahn · « **Reply #8 on:** September 17, 2007, 02:35:32 PM »

The problem with the BEC's and >3 Lipos in series is that when you load down the BEC with lots of servos, which can draw a lot of current, is that the BEC has to drop the battery voltage, >15V, down to ~4.8V or so. Since most of the BECs are linear, that means they have to dissipate the watts (=(BattVolt-4.8V)* Amps)internally--usually in the regulator. However for our timers, the draw is really small, so I doubt there is a problem in overheating the BEC. However the ESC may still turn off the BEC if that's the way it is setup. Since I am trying to standardize on 3s Lipo's (cheap-cheap!) I haven't had that problem.

It is true that the ESC works somewhat harder at partial throttle than at full, and that the battery current draw you measure on a watt-meter is only the average current over both the on and off cycles. However the Castle Creations say it is "ok" and the circuits are able to handle the higher instantaneous current during the "on" stage of the cycle (within the limit of current ratings and cell counts). I've been running my SuperClown setup at ~30-40% throttle settings with 10-6 and 10-6 props and haven't seen any problems with average current values in the 20A range (35 Amp rated CC Phoenix ESC and a 3s lipo). But maybe I am not stressing things enough!

We will see with my electrified Nobler. Coming soon.

Igor Burger · « **Reply #9 on:** September 17, 2007, 03:34:20 PM »

Quote from: Alan Hahn on September 17, 2007, 02:35:32 PM

It is true that the ESC works somewhat harder at partial throttle than at full, and that the battery current draw you measure on a watt-meter is only the average current over both the on and off cycles. However the Castle Creations say it is "ok" and the circuits are able to handle the higher instantaneous current during the "on" stage of the cycle (within the limit of current ratings and cell counts). I've been running my SuperClown setup at ~30-40% throttle settings with 10-6 and 10-6 props and haven't seen any problems with average current values in the 20A range (35 Amp rated CC Phoenix ESC and a 3s lipo). But maybe I am not stressing things enough!

It is not big problem with ESC or its efficiency, bigger problem is current in motor winding. If you have twice the voltage necessary for used rpm (8 cells instead of 4) the the PWM will make average current in battery may be half of the average current in winding ... because the average current in winding is only slightly less then peak current of pulses in battery, means the motor must be able to work at approximatelly 1/4 more power compared to well matched battery.

Dean Pappas · « **Reply #10 on:** September 20, 2007, 12:48:08 PM »

Hello Dennis and Archie!
Glad to see you playing with E-Stunt. let me list a few points that could take days to fully discuss.
1) You do want to run an RPM governor.
2) You want a governor with the fastest response time and highest gain practical without causing wild RPM oscillations
3) You will eventually need a prop brake that works in governor mode, but for the ESCs that don't have it, this is just upgradable software.
4) Though Igor correctly points out the thermal load downsides, you want to run the governor with lots of headroom in order to improve the airspeed maintenance of constant airspeed.
When all this is done, you would see better than a 2:1 peak:valley current ratio in the various parts of the maneuvers.
5) Diameter is king: the more diameter you turn at a constant RPM & pitch, the more constant the airspeed of the rest of the airframe that is tagging along for the ride, irrespective of where the nose is.
6) Lightness is next to ... Awww, you knew that already

looking forward to it,
Dean P.

Dennis Adamisin · « **Reply #11 on:** September 20, 2007, 03:59:43 PM »

Dean:
THANKS for the feedback! I guess the point of this whole excercise was a big ole "what if" using dirst simple components. The Brodak system is pretty basic, we put it into a far from optimised ARF yet it delivers surprising results. Young Arch is going to a tricked out a prop (per your item 5) Items 1- 6 are in the works...

Archie Adamisin · « **Reply #12 on:** September 21, 2007, 07:38:34 AM »

Dean,

Thanks for all the great tips. We are making progress very quickly with this system. I hope to have it all worked out by the end of the month. As I said in earlier posts, we are quickly outrunning the abilities of the Oriental airframe. It has been a great test bed to gather information.

The controller I have is a Kontronik 3SL-80-6-18 which I used in my F5D's in 2000-2002. I have (4) of these so I will be using them until I see the need to upgrade. They are fantastic controllers!! Harold Konrath was ahead of his time with the first of what is now the norm of sensorless controllers. The governor mode in this controller seems to react quickly in bench tests and when used in some helis I have seen. The motor runs amazingly smooth with this controller as well. I am going to go out and test tonight with this controller and with my new JMP timer. I am waiting on some props from APC, but if the hobby shop has a 10x5, 10x6, or 11x5.5 I will try those. The JMP will allow me to throttle back and control the current. I am going to up the static current from 32 amps to 35 amps to get a bit more power. I have plenty of run time right now. I am shooting for a 5.4 lap time & pull up on top. A larger disc should give the pull, and less pitch or less rpm will slow it down. I should have some more results by the end of the weekend.

Archie Adamisin

Muncie, Indiana

Dean Pappas · « **Reply #13 on:** September 21, 2007, 02:08:13 PM »

Hi Gang,
Oh, this is gonna get to be fun! Archie, if you are not running a governor, then of course you will be running a fixed throttle setting.
The best of all fixed throttle settings is FULL. Why?

The ESC runs cooler, the motor will also (assuming the prop pitch and load produce the same lap time)
The subtle bit is that torque vs RPM curve (actually a straight line) will be steeper at full throttle (voltage) and the appropriate low pitch prop, than with a higher pitch prop and partial throttle.
As you know already, it is in the nature of a DC motor with a fixed input voltage to make more torque if the load is increased, and a small RPM loss results. So even without a real governor the DC motor has semi-decent self governing characteristics. This means having a couple of props with slightly different pitches. Of course you will still get slowdown during the flight. Maybe a bit less than 2 tenths. This is actually how Bob was set up for the 2005 Team Trials, though by the 2006 Worlds we were on the governor. By this last TT, we had biased the setup to give the governor more headroom to allow higher peak currents under transient loading, and had more closely optimized the governor time-response.

The Genesis is presently using only 2600 mAH average per flight from its 4200 mAH batteries, and I think that 60 ounces could be flown with this setup.

later,
Dean

Igor Burger · « **Reply #14 on:** September 21, 2007, 02:29:34 PM »

Quote from: Dean Pappas on September 21, 2007, 02:08:13 PM

The Genesis is presently using only 2600 mAH average per flight from its 4200 mAH batteries, and I think that 60 ounces could be flown with this setup.

Does he use AXI? and what prop?

Dean Pappas · « **Reply #15 on:** September 24, 2007, 09:23:57 AM »

Hi Igor,
It's an AXI 2826/10 on 4 cells with an APC 12-6 E.

later Friends,
Dean P.

Igor Burger · « **Reply #16 on:** September 24, 2007, 02:19:35 PM »

Thanx, nice to know.

Rudy Taube · « **Reply #17 on:** September 25, 2007, 12:12:09 AM »

Hi Dean,

RE: your statement: "The Genesis is presently using only 2600 mAH average per flight from its 4200 mAH batteries, and I think that 60 ounces could be flown with this setup."

You are absolutely correct. This system flys my P-40 at exactly 60 oz. This is with my Eagle Tree test equipment on board that reads RPM, Watts, Amps, V, Motor temps, Battery temps, and then prints a graph of everything for the whole flight. This added 3 oz to my 57 oz plane. I have HD 5/32" gear, with 2 3/4" wheels to fly off of very rough grass.

At 60 oz. the plane flys as good, or better, than every plane I have seen at a contest this year. (The plane, NOT me! ;-) That includes some BIG iron here in the SW. The only planes that have the same "flys like a freight train on rails" quality are the Russian RTF, and Igor's big plane powered by a 4S, and the .75 TP planes. My system uses 3,200 mAh per flight, but I am too Conservative yet and have my time at full power set at 5min 45sec. I could reduse this and save some mAh, but then it would just add more grey hair from worrying about running out of time for the pattern!

I am on 62' E to E .015 lines with 5.0 lap times. My RPM in level flight is 9,180. It varies from 8,900 to 9,350 during maneuvers. I am in Gov mode.

I have been using the APC 12 x 6 for the last 50 flights. IMHO It is the perfect all around prop for this setup. Will Moore, and Linhart both recommended this prop to me a long time ago. I am glad to see you and Bob are now using it too. It really seems to help in the wind.

Thanks again for all your help with ECL.

Regards,

Dean Pappas · « **Reply #18 on:** September 26, 2007, 02:12:31 PM »

Hi Rudy,
Thanks for the confirming data.
I would even consider adding maybe 3/8" to 1/2" of diameter (12.5 X 6) when flying the slightly heavier ship.
That should up battery consumption to maybe 3000 ~3100 mAH.

Dean P.

Archie Adamisin · « **Reply #19 on:** September 27, 2007, 10:27:21 AM »

Well, after a few days of digesting numbers and relating them back to make sense from what happened this weekend, I am happy to report that the Oriental with the Brodak SC motor has shocked me back.

I took out the Brodak timer & ESC and replaced the timer with a JMP2 and the controller with a Kontronik 3SL 80-6-18 non BEC controller. I used a (4) cell 110 mah rx pack to power the controller & timer, and a micro on/off switch to power on the controller. The motor and batteries (4000 mah 15C) are stock from the SC setup.

I did a static test with a 10 x 5 APC -E to establish the timer's throttle position and static current. 100% throttle yielded 12,100 rpm @ 48 amps. I throttled it back to nearly 50% and got the current down to 35 amps with an rpm of 11,000. I have calculated that the required rpm for 5 pitch with 67.5 ft radius center to center to be 11,100.

I set up the JMP timer to spool up for 15 seconds @ 15% throttle, then run @ 56.3% for 2:45 and then ramp up to 60.9% from 2:45 to 5:30. Flight resulted in a 5.8 second lap time that I had enough power to do the pattern, but the airplane wasn't happy at that speed. The surprise came when the final lap speed was 5.35. So the batteries didn't fall off as expected. So I adjusted the timer for 59.4% (26 steps from 100%) for both the first flight speed & the final flight speed. The result was a 5.5 lap time through the flight. I have flown it this way 4 times in a row with no changes and it has repeated.

Notable things about these flights were that the Kontronik has a governor and that the flight speed through the maneuvers and in level flight remained constant. I had pull in the overheads!!!

I flew in dead calm and in 15 plus wind. Downwind maneuvers never whipped up. The even more surprising conclusion was the motor and battery were cooler after the windy flight than they were after the dead air flight. This meaning to me without in flight data that the motor was working less in the wind. I confirmed this when I discharged the packs after getting home from (2) different flight sessions and saw that it took 2300 mah to fly in the wind & 2550 to fly in the calm. (These results were from the same battery pack)

I don't know what the parameters of the Castle or even for that matter the Kontronik controller, so the throttle position may be dependant on controller choice.

My results show that over my 5:55 total run including spool-up averages 24 amps @ 266 watts. This would give an average of 90.6 watts/lb. The airplane flies with authority and performs better than I thought an Oriental could. But what is the underlying message here; How much power does it really take to fly a stunt pattern?

To all those who own the Brodak SC setup, get a new timer and a governing controller and you have a set-up that will fly a 550-600 sq in stunter weighing less than 48 ounces. (3) cell setups are viable solutions for Classic sized airplanes and should be considered to keep the wing loading down. I would put this setup in a Talon built for electric in a second. I have every expectation it would do a great job.

Archie Adamisin

Muncie, Indiana

Dennis Adamisin · « **Reply #20 on:** February 05, 2008, 11:38:57 PM »

Just wanted to dust off this old thread one more time. Young Archie has been vying for a break in the weather - for the past couple of months - to prove-out the "final" power systems in this bird. Since the test plane is the same size/slightly heavier than my pending "Swinger" (see that thread in the Classics forum) and he was proving out the system I intended to use I was GENUINELY interested in this session!

* Looks like I'll be using the 35-30-1250 Rimfire motor with Phoenix controller, JMP timer and 4Sx3000 pack, all to turn a 10x5E APC. Indications are that the pack MIGHT be a little over-sized but that will have to wait until we get "campaigning" and really start to live/work with the system to determine whether we can use the next size smaller (2500's???).

* The Motor is only 2.5 oz, the battery around 11 oz. Thus the total package is not unlike a typical 40 size unit typically used in a classic sized bird.

* Our experiences seem to parallel the E-Nobler from Germany that Bruno talked about a few months ago. I am intrigued (maybe bewildered is a better word!) that we are achieving the success we have with such small components. Time will tell whether it is truly successful.

* Nearest analogy I can draw is the early "Speed 600"/ 7-cell nicad power systems our RC friends pioneered - only to discover that they could get comparable performance from smaller "Speed 400" components still using 7 nicads but of smaller capacity and weight. Probably the lesson is that the power & weight spiral works both ways (and weighs!)

* Meanwhile along with the Classic "Swinger" I am commiting myself to build a "real" CLPA bird using the next size larger Rimfre 35-36-1200 which will enable me to comfortably use an 11x5.5E prop. For the intended design that will be a solid power-up versus the last slimer version of that design.

* BTW Archie also proved out the Brodak motor, reversed for firewall mounting, and using 3 cells. 3 cells actually looks viable in this power range (10x5E) - but the battery must be of higher capacity, and the tie-breaker may come down to simply the size & shape of the battery!

Dean Pappas · « **Reply #21 on:** February 06, 2008, 08:12:33 AM »

Hi Dennis,
So what was the all up weight in the most recent test

That would be for the package that looks like ...

quoting from Dennis "Looks like I'll be using the 35-30-1250 Rimfire motor with Phoenix controller, JMP timer and 4Sx3000 pack, all to turn a 10x5E APC. Indications are that the pack MIGHT be a little over-sized but that will have to wait until we get "campaigning" and really start to live/work with the system to determine whether we can use the next size smaller (2500's???)."

And how much battery capacity did the first flights actually use? Consumption will hardly change from cool to warm weather, even though the RPM setting will change.

Sounds exciting!
Dean

Thierry SAUNIER · « **Reply #22 on:** February 06, 2008, 03:29:48 PM »

.....Consumption will hardly change from cool to warm weather, even though the RPM setting will change.

Hi Dean,
Can you please give your experience on those differences in A/h between cool and warm weather? can you quantify this? I would appreciate to read about that - and compare to what I noted.
Rgds, Thierry

Dennis Adamisin · « **Reply #23 on:** February 06, 2008, 06:45:40 PM »

Hi Dean

The Oriental has been flying between 47-49 oz depending on which motor & battery are on board. Battery usage info has some "noise" in the data. Do not have several repeated flights using the SAME setup. Latest flights where somewhat fast (5.1-5.2 sec lap times versus target 5.4) With the 4-cell were using between 1900 & 2100 mah--- a little snug on the 2500 pack! However it is safe for the 3000 pack. Frankly until we get really flying this thing in different conditions and getting more repetitive data data I'd have to say the 2500's are tantalizing! Put another way, we have "committed aviation" but there is a LOT of learning and experience to go!

My Nephew plans on posting some of the Eagle Tree data. That is good to know but I am relying more on my assometer evaluations - i.e. having my... (tail) in the center of the circle hanging on to a PATTERN. Those "tests" suggest that the e-powered Oriental is at least as powerfull as the LA40 powered Oriental I flew last summer.

One thing of interest is that the Oriental really does not like to fly with an 11" prop! There's lots of thrust available but the short coupling and small tail are much happier steering a 10" prop. A pleasant surprise was that 10" prop still does a nice job of preventing wind-up in the wind. That is why I have described this as a "classic" sized power system - because it should happily replace what ever engine you were using to turn a 10x6 prop - like most of the classic era birds.

BTW it looks like test flights with the Eagle Tree on board will be part of the trim regimen. Not sure its needed once the set-up is dialed in. Probably should get in the habit of logging charge current on used packs.

My first application will be in the Jack Sheek's "Swinger". Building this was a good excercise; I left a lot of wood on the table - and should have left a whole lot more! The next bird, a "real" airplane will be a straight-forward update of a bird I know is not power hungry... The challenge will be for me to leave out more wood...

Archie Adamisin · « **Reply #24 on:** February 07, 2008, 06:26:45 AM »

Here are the Eagle Tree plots for (3) different motors. All plots were using the Phoenix 60 controller in governor mode. The 35-30-1250 plot had trouble on the RPM curve and I have omitted it from the curve because it really throughs it all off. The lap time on all these plots were 5.15-5.2. The only difference that I could tell between all these flights were the Brodak motor sounded different because it is 10 pole versus 14 pole on the Rim-Fires. The overall power was the same. It flew the best with the Rim-Fire 35-30-1250 because of the lighter weight. The 35-36-1200 plots were taken on a day that it was windy 10-15 mph & 45 degrees. The Brodak and 35-30-1250 plots were on a perfect stunt day 3-5 mph, but 35 degrees. You can see the effect of the cold weather on the voltage as it increases over the flight. I used hand warmers to keep the packs warm, but I had limited success with it.

The amazing points of interest here are the plots from the 35-36-1200 & 35-30-1250. They used they same amount of power! The motor geometry is completely different.

I have also attached a plot of the 35-36-1200 on a 11 x 5.5 APC which it used the least amount of battery, but almost made the Oriental un-flyable. It wouldn't turn!!! It pulled the hardest of the bunch.

With all this being said, there is still a lot to be fine tuned in this system to drop the capacity used by slowing the lap time, and possibly shortening the lines to 61'. A lighter airframe would also help to save power. Regardless, the 35-30 (2808 AXI) platform is viable for classic models and if I can get the capacity down, system weight would be in the 12 oz range which will make it completely interchangeable with glow power in models of this size. The 35-36 (2814 AXI) platform is also a great size, but it has much higher output capabilities than the 34-30. It would be better suited for 600 to 630 square inch birds up to 52 ounces. Something like my Gemini Mk1 would be a perfect candidate for that motor size.

Enjoy!!

Archie Adamisin

Muncie, Indiana

Archie Adamisin · « **Reply #25 on:** February 07, 2008, 06:31:37 AM »

Here are some pictures of the Oriental with the Rim-Fire installed. The cut-off spinner really helps to cool the radially mounted motor. We have converted the Brodak to this mount type as well and is interchangeable with the Rim-Fires.

Archie Adamisin

Muncie, Indiana

Archie Adamisin · « **Reply #26 on:** February 08, 2008, 07:13:27 AM »

Now for the Million dollar questions:

1.) What is the relationship of motor performance to stack length & diameter?
2.) What is the relationship of Kt (in-oz/amp) to stack length or diameter?
3.) Do out-runners suffer from iron losses like in-runners do?
4.) Has anyone reached a maximum efficient rpm for an out-runner?
5.) What is the magic Kv number for 4S?
6.) What effect does the Kv have on Kt and current for given rpm?

Here are some pictures of the Brodak installed using the backplate mount. Conversion was simple. We lossened the set screws and moved the shaft until enough was left to put a wheel collar on. The shaft sticking out the other side is sufficient to use the supplied collet assembly. Big Art

made the (3) bolt mounts for the Rim-Fires & the Brodak so that all are interchaneable. The Oriental was ready to fly with a Brodak .40 before Uncle Dennis converted it to electric. This is why the cowl is hollowed out on the bottom. I would like to replace it with an uncut cowl to create better system cooling.

Oriental RTF weights per system:

Brodak w/Brodak (15C) 3S 4000's = 48 ozs
Rim-fire 35-36-1200 w/Maxx Amps (20C) 4S 3000's = 47 oz
Rim-Fire 35-30-1250 w/Maxx Amps (20C) 4S 3000's = 46 oz

Archie Adamisin
Muncie, Indiana

Dean Pappas · « **Reply #27 on:** February 08, 2008, 10:04:19 AM »

Quote from: Thierry SAUNIER on February 06, 2008, 03:29:48 PM

.....Consumption will hardly change from cool to warm weather, even though the RPM setting will change.

Hi Dean,
Can you please give your experience on those differences in A/h between cool and warm weather? can you quantify this? I would appreciate to read about that - and compare to what I noted.
Rgds, Thierry

Hello Thierry,
I owe you an e-mail from a long time ago! Please accept my apologies.
This is based on watching the consumption of Hunt's E-Genesis from the heat of Summer to late Autumn. The total capacity used for the flight is virtually unchanged, though the RPM must be lowered in the cold, dense air to maintain lap time. The Genesis used maybe 2600 mAH in the warm and maybe 100 mAH more in the cool air. The available battery capacity does go down in the cold, so if you use 80 or 85% of the warm-weather capacity, then you may be in for a surprise in the overheads and clover.

What have you seen?

regards,
Dean

Dean Pappas · « **Reply #28 on:** February 08, 2008, 11:02:17 AM »

Hi Archie,
Excellent questions: some of which defy a simple answer. I'll try anyway.

1.) What is the relationship of motor performance to stack length & diameter?

More diameter means bigger pole face areas (for a given number of poles) and more torque (both because of the bigger areas and the larger radius) BUT it takes more wire length to go around that bigger face and that adds resistive or copper losses. More stack length means much the same, though the longer a stack is compared to how wide, the better use you get from the copper. (The wire wrapping around the ends is just added resistance, if you could somehow magically beam the current from the wires on one side of the pole face to the other.) Inrunners usually have better shapes in this regard. More about diameter in #3

2.) What is the relationship of Kt (in-oz/amp) to stack length or diameter?

They are bound to each other by physics! If Thomas Jefferson had won that all-important argument 200-something years ago, and we used a rational system of weights and measures, then you'd see that Kv (expressed in Volts per radian per second ) is exactly the same number as the Torque constant (expressed in Newton-Meters per Amp) But, we use feet, slugs and quarts, not to mention that we like to show Kv as the inverse of what was in my textbooks in school, so we use RPM/Volt. in any case, for the same weight of copper and the same magnets and iron, if Kv (RPM/Volt!) goes up 10% then the torque (in oz-in/Amp) goes down 10%.

3.) Do out-runners suffer from iron losses like in-runners do?

Yes, and moreso, because the magnetic path in iron or ferrite or whatever is longer in an outrunner. The motor design gurus are haggling over the reletive merits of high RPM (then geared) outrunners. There are additional losses with faster and faster pole-passing frequencies, and that's why motor diameters don't grow a whole bunch to get lower Kvs with more poles. The holy grail is a motor geometry that needs no iron. This involves magnets with fields that make "U" turns. If you are terribly bored, go Google Halbach motors or magnets or ironless-slotless motor.

4.) Has anyone reached a maximum efficient rpm for an out-runner?

I don't understand the question.

5.) What is the magic Kv number for 4S?

'bout 900 with a governor, maybe a little lower if running at full throttle.

6.) What effect does the Kv have on Kt and current for given rpm?

See my lengthy answer to #2.

Dean

Dean Pappas · « **Reply #29 on:** February 08, 2008, 11:13:39 AM »

Hey Archie,

I quote, "I have also attached a plot of the 35-36-1200 on a 11 x 5.5 APC which it used the least amount of battery, but almost made the Oriental un-flyable. It wouldn't turn!!! It pulled the hardest of the bunch."

Do you agree with my subjective look at the plots in that the 11-inch prop has a higher peak to average consumption ratio? It's not single peaks, but how much and for how long the current rises in each climb.

So if the plane turned with the 11-incher you'd run one, right? Try a lighter (in ounces) prop, like a thinned wooden one. I don't think it will make much difference. The next step would be lower Kv and RPM on an 11-7 prop. That would require a motor with a Kv of ... 900! I do think that that will make a difference. Granted, we are up against an old friend: more diameter always pulls better, but kills turn, so we compromise.

Dennis,
I don't think you are going to get your per-ounce energy consumption down any further. So how much will it cost to only get 75 "good" flights out of a set of 2500s. Is it worth the two(?) ounces?

Dean
Dean

Dean Pappas · « **Reply #30 on:** February 08, 2008, 01:47:57 PM »

Hi again Archie,
I have another pesky question.
Does the airplane fly better with the 1 oz heavier 35-36-1200 Kv motor rather than the 35-30-1250 Kv? Even just a little?
Yes, they used the same total energy to fly, but the two datalogs show me that the motor with bigger magnets and bigger iron shows a slightly higher peak to valley current ratio. The one ounce heavier 35-36-1200 has an internal resistance of 41 milli-Ohms according to the datasheet, while the 35-30-1250 has 112 milli-Ohms. This means that if and when the governor "punches" the throttle, the 1200 motor will pull more current, more quickly, and so the momentary decrease in RPM that happens as you turn a corner gets quashed more quickly. That is, it pulls even harder just when needed. Besides, it will also be a little bit more efficient! That cancells out the extra power that gets used, apparently.

So what I'm asking is does the feel bear out what the calculation shows. Given two motors with similar Kv, does the lower resistance motor Stunt better?

Dean

Archie Adamisin · « **Reply #31 on:** February 08, 2008, 02:40:25 PM »

Dean,

Thanks for the lengthy responses. You have answered many questions I had and raised even more. My experience with out-runners is limited to what I have experienced with this project. My F5D/speed 400 racing experience is with in-runners. I have Hacker B-40 in-runner motors that have slottless stator assemblies which have zero cogging effect. They are packed with copper using multistrand small guage wire and it is compressed in the motor casing. I can also remember to old Astro cobalt brushed motors that used slotted armatures with angles that reduced the cogging effect. Point of this story is your mention of copper losses with more copper content if I am understanding you correctly.

I'm glad you found the specs for the Rim-Fire 35-30-1250. I knew the resistance in this motor was higher than the 35-36-1200, but your numbers show it to be quite a bit. That's a surprise. I need some better testing equipment to take some measurements.

Flight comparisons between the (2) Rim-Fires is mixed. The JMP throttle settings are different to obtain the required rpm setting. It took 35.94% (23 steps from 0) on the JMP timer for the 35-36-1200 where the 35-30-1250 took 43.75% (28 steps from 0) to achieve the same 5.2 lap time. Once in the air though, it really dosen't feel different. I would really need to have a full day test session and interchange the motors to get the true feel difference.

Comparing the graph to me was a surprise when the same total power was used by both motors. I thought that the smaller peak and valley concentration on the 35-30-1250 would be more ideal and more efficient.

Flying with the 11 x 5.5 was on the verge of feeling that the airplane might come apart. The thing was pulling very hard and had pull all over. I felt that this kind of power needed more airframe.

I have made the generalization that the higher the Kv, the lower the resistance typically. This was usually the case with the in-runners I used in the past. This of course is a flawed generalization, but for high performance motors usually held true. Looks like I have a learning curve on the Out-runner motor design.

Next to the controller. I have mentioned in the past about how I have been unsuccessful in setting the lap times using the Pheonix controller. I really like the governor response, but in level flight, I have had some concerns that the motors aren't running steady. It almost sounds like they are missing. Both Rim-Fires do it, yet the Brodak runs smooth. Is this something to do with the throttle response, governor gain, motor timing, PWM rate, etc.

??

I can't wait to get a purpose built stunter in the air. Uncle Dennis has the jum on me with the Swinger, but he is moving on to the CLPA which I believe he will use the electric system. My dad is building a Knight which he is waiting to here from me on power-system choice. From the numbers and the weight savings, I would tell him to go with the 35-30 platform using 61' lines and 4S 2500 mah pack. What haven't I seen in these plots that would make me think differently? Do I need to look at these plots differently?

Thanks for the great tips!!

Archie Adamisin

Muncie, Indiana

Dennis Adamisin · « **Reply #32 on:** February 08, 2008, 07:20:51 PM »

Dean:
Great stuff - thanks for taking the time for the answers.

How far the downward spiral - yes there are limits. For instance, for instance, per "Uncle Deano's ROT for LiPo's" I would not commit to a 2500 mah pack unless I could CONSISTANTLY demonstrate per flight battery usage of < 1875 mah. Not quite ready to make that commitment - Archie is leaning that way.

Comments on weight: Way back in the 1970's GM learned that for every pound they could save in the body shell, the total car could get lighter by 3 lbs: lighter body allowed a lighter chassis, and then the powertrain could be made smaller. I would not use the same fractions for CLPA but suspect a similar philosphy applies: If we can save weight in the airframe then the powertrain components can get smaller: 1 oz savings becomes 1.xx savings for the total airframe because the motor, battery, wheels, landing gear, etc can all be made a little smaller. Of course as the weight goes down another round of lightening is possible: Lighter total weight allows even lighter strucural weight eventually allowing smaller motor & battery. Yes I agree there are practical limits - but unfortunately I am no where near those limits. People routinely build comparable sized birds 6-8 oz lighter than I do! But I use this only as an excercise showing why I think the weight can "spiral" down at least a lighter farther than I am.

Trouble is the batteries do not dial down in size, they change in steps. Thus to safely save those 2 oz or so in the battery, I might have to save 6-8 oz in the airframe. Possible - even probable for a light builder but a nightmare challenge for me!

You mentioned the governor "kick" pulling through a square corner. The larger motor is about 1 oz heavier - certainly some of that weight is in the longer magnets and motor casing. Acclerating that slightly larger mass of course require a bigger kick & current spike... how important do you think the physical mass of the motor shell is to that spike? Do you think the shell of an outrunner be thinned or ventillated (made lighter) without adversely disturbing the magnetic flora & fawna???

I intend to have my assometer in full attention mode, watching for governor "kick" when I start flying the two motor choices we think will fit the Swinger!

Dean Pappas · « **Reply #33 on:** February 09, 2008, 02:53:06 PM »

Hi Dennis,
Flora and Fauna ... I almost immediately think of Frank Zappa's Dynamo Hum!
Let's see, we have two motors that are the same construction and diameter, but one is a little bit longer.
Assume that most of the added weight difference between them is in magnet, mag-path iron, and working copper. This would (or might not) be true with diameter or manufacturer motors.
The benefit is better effieciency, cause the same mechanics are carrying more magnetic path "guts".

As you say batteries come in lumpy capacity flavors. Sooooooo
if you just happen to use a whole 75% of the battery and IF you just happen to pick a motor that offers a better improvement in % efficiency than the heavier motor would cost you in % of the all-up weight (juggling just a few % here) then you get more performance: i.e. a better Watts-out to weight. Watts out of the motor is everything.

As far as the how much "kick" do you get per RPM of momentary prop rev speed drop? Well Anything that yields more INSTANTANEOUS WATTS to keep the prop speed constant, the better we will feel at the handle.

hope that muddies the waters properly!

Dean

Dennis Adamisin · « **Reply #34 on:** February 09, 2008, 06:47:58 PM »

Muddy Waters, but not the blues!

I was just speculationg that motor inertia = useless watts, less weight = less inertia = more watts applied to the problem at hand.

Oh heck, time to stop thinkin & talkin and start flyin..!

Hey, you gonna be at Toledo? I'll let you buy me a... root beer

(your welcome)

Dean Pappas · « **Reply #35 on:** February 10, 2008, 11:59:14 AM »

Hi Dennis,
I dunno 'bout Toledo. I sure would like to, though!
The added motor inertia is a second order effect. I wave my hand dismissively

Okay, here's a homework assignment for Archie: Holder of the datalogger files, master of the family E-experiments ...
In F3A (Pattern) we looked at the current waveform, figured out which current spikes corresponded to each and every climb in the pattern, then added up just the mAH that were accumulated during those climbs. We figured out that 2/3 of our battery went to climbing, and only 1/3 to fighting drag in all the level lines. By the way, it was easier to do this by importing the log file inbto Excel. Does this ratio hold in Stunt? Hmmm.

The point is that the energy goes into the climbs, not spinning the motor up and down. That explains why power consumption is remrkably constant despite prop and weather changes, as long as we adjust to fly the same lap time.

later,
Dean

Dennis Toth · « **Reply #36 on:** February 10, 2008, 08:43:19 PM »

Archie,

With the 11x5.5 APC causing the slow turns you might want to revise the flap_elevator ratio to something less than 1:1. The older short couple designs were originally set up with around 30deg flap 45deg elevator. This is what we went to on the Still Stuka and the corner improved greatly. Other option that might be interesting to see is a 3 blade 10x5.5 or so maybe with a little undercamber to pull out of the corner.

Best, Dennis

Archie Adamisin · « **Reply #37 on:** February 11, 2008, 08:07:10 AM »

Hello Dennis,

I really like the way the Oriental flew with the 10" diameter. It had plenty of pull and it turned well. It was surprising to me that the 11 x 5.5 had the effect it did because Uncle Dennis flew his glow Oriental with a LA-40 and 11 x 5 power point and it flew fine. The big difference is propellor efficiency. The APC "E" props pull so well, that the effect is magnified when changing props. I just don't think there is enough airplane for that combination. The best match so far has been either of the three motors on the 10 x 5. I have also flown it on the 10 x 7 APC E prop and it flew well, but in the wind, the high pitch really wound up in the maneuvers even with the governor working. I would love to have a 10 x 5.25 or 10 x 5.5. I have a damaged 11 x 5.5 that I plan to cut to 10" and rebalance as another test. WHERE IS THE GOOD WEATHER!!!!!

Archie Adamisin
Muncie, Indiana

Dennis Adamisin · « **Reply #38 on:** February 11, 2008, 10:57:10 AM »

Quote from: stuntguy13 on February 10, 2008, 08:43:19 PM

Archie,

With the 11x5.5 APC causing the slow turns you might want to revise the flap_elevator ratio to something less than 1:1. The older short couple designs were originally set up with around 30deg flap 45deg elevator. This is what we went to on the Still Stuka and the corner improved greatly. Other option that might be interesting to see is a 3 blade 10x5.5 or so maybe with a little undercamber to pull out of the corner.

Best, Dennis

GOOD CATCH!

The Oriental was set-up from the get-go with 2/3:1 flap to elevator and clipped flaps to to help the too-short & too-small tail work as well as it possibly could. Flies well with a 9" or 10" prop, but it starts going south with the 11" even with the MUCH better thrust. Like Dean(?) suggested, it MIGHT get a little better if were to replace the prop with a MUCH lighter (probably reworked) wood prop - and I would consider that if this was a REAL airplane. But it is only the test bed that has served amazingly well. We have what we think we need to go forward with "real" birds.

One thing I have noticed about the two Orientals (one slimer and the electric) that I set-up last summer - the birds definitely tell you when they are not happy and give great feedback when when you make even small trim changes. In short the Oriental remains a really good entry level stunter, that just starts falling short when you ask for Precision Aerobatics... I'd recommend it in a heartbeat to a newbie or a "retread" getting back in the game.

one of the OTHER Dennis'

Dave Evar · « **Reply #39 on:** March 04, 2008, 08:25:35 AM »

Its shocking what you guys did to the Oriental(s). So shocking I am attempting to do the same with a Brodak ARF Smoothie.

I have most of the stuff worked out, but am concerned about the exhaust venting of the battery compartment, formerly the fuel tank compartment. I was considering cutting out some of the "soft" interior lumber to aid airflow and placing vent blisters over the flap hing line on both sides to draw away the heat. Intake air is not a problem.

Any suggestions would be greatly appreciated.

Dave

Alan Hahn · « **Reply #40 on:** March 04, 2008, 09:53:21 AM »

Dave,
I don't want to really admit it, but my battery cooling in my E-Nobler Arf was/is pretty miserable, but to be honest, my batteries were just warm after a flight. We are generally really not pushing our equipment in CL PA.

If I look at my data from the E-Nobler I am seeing about a 1V drop in battery voltage during level laps with currents in the 20 Amp range. I am looking at the end of a flight when the timer turns off and seeing how much the battery voltage jumps up with the current off.

That translates into a 20 Watt loss in the battery alone, or about 5 watts per cell (this was a 4s pack). If I were flying for 20 minutes like this maybe I would be really worried, but this is "only" over a 5 minute period.

It certainly doesn't hurt to get some air in there, but it doesn't really help the 2 cells in the center of the pack anyway (on the 5 minute timescale!). I think the main thing is to have them so that air can at least get around the surface of the pack (in other words, don't cover them in styrofoam or equivalent in an attempt to hold them in place).

What I am really trying to say is to not obsess too much

-- get some air back there and out, but it doesn't have to be a hurricane equivalent. The true test is that if the packs are warm to the touch just after you pull them out, you are cooling sufficiently. They should not be hot to the touch, that will probably decrease their expected lifetime.

Dennis Adamisin · « **Reply #41 on:** March 04, 2008, 10:19:31 AM »

Quote from: Dave Evar on March 04, 2008, 08:25:35 AM

Its shocking what you guys did to the Oriental(s). So shocking I am attempting to do the same with a Brodak ARF Smoothie.

I have most of the stuff worked out, but am concerned about the exhaust venting of the battery compartment, formerly the fuel tank compartment. I was considering cutting out some of the "soft" interior lumber to aid airflow and placing vent blisters over the flap hing line on both sides to draw away the heat. Intake air is not a problem.

Any suggestions would be greatly appreciated.

Dave

Dave:
I see that was your third post - WELCOME TO STUNT HANGER!

If you SEARCH on StuntHanger you should be able to find a thread by Bob Branch on his electric Smoothie conversion - should have things you can use.

On the Oriental I did almost exactly what you described. I punched out the soft bulhead at the top of that rear tank bulkead, then cut some slots in the top of the fuselage around the trailing edge of the wing. Did a similar thing at the bottom with a vent at about the high point of the wing.

Finally I agree with what Alan said about not obsessing over it. To it another way, I think it would be good to make sure you do not CREATE hot spots by boxing the battery in. Oh yeah, make sure it is retained/captured (softly!) so it cannot flop around...

Dave Evar · « **Reply #42 on:** March 07, 2008, 11:07:36 PM »

Thanks guys. Problem probably solved.

Dave

Archie Adamisin · « **Reply #43 on:** March 12, 2008, 10:21:52 AM »

Knowing all those guys are out there in the Tuscon sun, I had to take advantage of the Muncie warm spell and flew the Oriental again yesterday. This flight was to test the Turnigy Sentry 60 amp controller. An optional programming card make programming a breeze. I have been testing various controllers to settle on something. It is a very inexpensive controller, but offers a governor mode, brake arming while in governor mode, three timing advance settings, and a balancing plug that balances the pack through the discharge up to 4S. I have attached the Eagle Tree plot of the performance. It flew @ 5.2 sec/lap which was a bit fast, but very smooth. The Brodak motor ran well with this controller set @ medium advance. I set the JMP timer to 65.625% (22 steps from 100%) and the static RPM on the 10 x 5 APC E was 10,680. Static current was 38 amps. I am going to fly again today shooting for a 5.4-5.5 lap time like I was able to accomplish with the Brodak motor and Kontronik 3SL 70-6-18 controller.

Note that this controller is not up to par in its ability to govern like the Kontronik Jazz, Kontronik 3SL, Castle Phoenix, or the Jeti Spin. It is however a good controller for those who want to get started and even compete in ECL. Prop choice for this controller is pivotal and other motor choices may make it better. I will post more results as I test more motors.

Archie Adamisin
Muncie, Indiana

Dean Pappas · « **Reply #44 on:** March 12, 2008, 01:43:45 PM »

Hi Archie,
Thanks for the new info. Yes, the governor is nowhere near as tight: the peak to crest currents are 20% where the same prop on the 35-36 motor and CC was about 3:1!
I do like the idea of the low-voltage cutoff responding to any one cell in the pack, though. That will be good for saving packs from accidental abuse. Several outfits, like FMA, sell add-ons to do the same.

later,
Dean

Alan Hahn · « **Reply #45 on:** March 12, 2008, 03:10:00 PM »

Dean,
I'd worry about a single cell LV cutoff in stunt. If a cell is going south, the battery pack is probably getting ready for the recycle bin anyway. With a LV cutoff--at an inopportune time in the pattern---it might bring the plane with it (except the plane probably doesn't go into the recycle bin, but into the trash bin directly!)

One thing I like about the FMA charger is that it will give you a voltage reading on each cell as you recharge. Maybe I should make a habit of actually looking at it at the beginning of a charge to detect single cell problems before flying with them.

Dean Pappas · « **Reply #46 on:** March 13, 2008, 08:08:33 AM »

Hi Alan,
I've gotten in the habit of checking each individual cell almost immediately post-flight.
The 3.0 V cutoff is quite conservative. I'll bet we never see anything as low as 3.3 V per cell, even when the batteries are used hard.

Dean

Igor Burger · « **Reply #47 on:** March 13, 2008, 08:31:40 AM »

A friend of mine here close in czech make a small PCB which can be connected ro balance connector of battery. It has led diodes and they will flash if a singe battery voltage drops down under preprogrammed voltage. So it is easy to chech every cell DURING the flight, it will show if the battery is still healthy. Additionaly it can either switch on some external device (external light) or cut off the power signal from timer. It is for 8 cells.

BTW the esc cut off voltage is very important. It is right that it can make crash, but if you set it properly (read to very low voltage) it can help in case that you forgot to charge the battery, it clear after start that something is wrong, so it will stop the motor in level flight (guess how I know

)

Alan Hahn · « **Reply #48 on:** March 13, 2008, 12:56:53 PM »

I guess one needs to be sure what kind of shutoff you have (or have enabled) on the ESC.
On my setup (CC Phoenix), I have what is called a "soft cutoff". It doesn't really shut power off, but slowly begins to lower the throttle to protect the battery.

With my RC planes, I have a hard cutoff, that actually turns the motor off when it is reached. You can get power back by throttling back to low throttle, so you can make it back (using low throttle) to the field if necessary. Of course you don't use such an extreme cutoff with 3D models or helicopters because you are almost always in a situation where there is no time to get to reduced throttle. Of course in CL we don't have the rearm option--unless you happen to accidentally be near where some timers blip the throttle to zero.

I think the real story is to make sure you know what is up with the battery before pushing the "go" button. I realize I need to check a bit better than I do now.

Thierry SAUNIER · « **Reply #49 on:** March 13, 2008, 05:14:15 PM »

Hi Guys,
It happened to me to accidentally start a 5mn30 flight with a half full lipo pack...a real disaster! Here's how I did: For short settings trials, I have several JMP's set for 1 mn flight (exactly 72s = Run Up Time of 12s and 1mn flight time) So I can make several trials out of a single fully charged pack.
Then with the right setting I change to a normal 5mn30 JMP (I do not like to change the program of these on the field..) AND of course, I have to change the pack for a fresh one...except when I did'nt
Now, how does the ESC and the Timer react... when the voltage falls down the 3V/cell, the ESC security cuts, but the JMP rearms for a full throttle, but the ESC security cuts off, and the JMP rearms... and so on untill the pack is so weak that the plane will be forced to land and roll around untill a helper is able to catch the model OR if you get saved by the term of the 5mn or so.
May I describe the Lipos after that? Sure I won't.

Another possibility? YES , you just program the JMP for an infinite flight time...just do not lock the program and play with the pushbutton by inadvertance... I have tried both!

Last: I just wonder what would happen to my D 520 with retract, if... Will I be able to whipping the bird untill the JMP tells the retract to go down?
But this is nothing but fiction.

Thierry