Guys

I have discovered a new tool needed for flying a large BRUSHED motor plane. A commuter cleaner (four bucks). I thought my motor was going bad or that I needed new brushes. I talked to a CAR/Boat guy and he told me to get the commuter cleaner. One end is shaped to go down the hole where the bushes set. Push it in and spin the prop. The commuter, which makes contact with the brushes is shinny new. The other end is shaded to clean the C shaped brushes. My commuter was so dirty that the Speed control would not boot up. No complete circuit. I thought it was bad. Thanks pmpjohn for the advice.

Save a few $ and cut down pencil erasers to clean the commuter

Save a few $ and cut down pencil erasers to clean the commuter

MerlinL14

Yes, I try to save $ whenever I can. Thanks for the advice.

Guys


I switched the Avistar to a GP3300 pack and still had power problems. I pulled the brushes and they looked clean. When I put them back in, I couldn't get a complete circuit. I pushed on the brushes with a screwdriver and the speed control activated for a second then lost contact. Since I had a spare brush set at home, I put the Avistar back in the truck and flew my Funtana.

Back at home I pulled both brushes. One was worn shorter than the other and both were shorter than the new ones. My guess is the shorter length of the brushes kept the springs from keeping a tight fit against the commuter. I put in the new ones and things seem fine. No trouble booting the Griffen 55 now. Test flying in AM.

My 1900 mahSCR pack is most likely still good. It still gives 1.2 V per cell.

Fantastic!!


With the new brushes and GP3300 battery (8 cells) and 13x8 prop my Avistar goes and goes. I landed after 8 minutes then taxied to my truck. Great! Just great! I can see more of these GP 3300's in my future and in my planes.

Guys


To keep those endoplasma motors going you have to change the tension spring as well as the brushes. Who would have thunked it!

Are you still running an endoplasm motor? I have my second avistar I built for my brother to learn to fly on (gave away my first glow powered one) and is complete except for power and after finding your thread, I am going to buy a complete setup, the question seems to be Jeti30-3 or the endoplasm which you seem to be having good luck with. What did you finally settle on for a setup or is it still work in progress?

Log


I use the Endoplasma in mine. I like being able to show off my big BRUSHED plane at the FF. I would suggest that you use a JETI 30-3 eitherDD 8-10 cells w/GP3300 or GB 2:1 on 10-12 cells GP3300. The brushless setup is less $ in the long run. There are no brushes to change out. You can use a $12.99 GP GB but the included pinion won't fit. You need a 5mm 16 tooth gear which cost $12.00 from MEC Plus shipping. DD will get you 8 minutes and GB will get you 10-12 minutes.

I found a Jeti at my LHS, thanks for all the info, I have a possible SQ (stupid question), who is MEC?

Logster,




www.modelelectronicscorp.com


go to pricelist.


Remember that the Jeti is limited to a 2:1 GB. Beyond that magnets get ruined. You need a 16 tooth 5mm pinion gear($12.00 plus postage). 10-12 cells 15x8 prop.

8-10 cells with 12x4 prop Direct Drive is good too! With less extra cost.

Thanks again, it is always good to converse with someone who has been there, done that.

Log



Post some pic if you can.

pics

Logster


Did you ever finish that plane? Mine is still going!!!

Guys


I'm going through a lot of brushes with this set up. I have the twin speed 400 drive system from my Extra 300 fixed with 2 new HL Rocket 400 motors. I will try putting it in the Avistar.

Okay!!



250 watts with 8 cells and a 11X8.5 prop and 320 watts on 10 cells.

wouldn't fly on 8 cells

guys!!



10 cell packs are only 1950 mah. Why even take off?

Back to Endo or brushless.

Agreed. The 12 volt 1950 mAh flies the Avistar at a minimum of 33.3 Amps (depending on your planes weight). This is eating a good bit of your motors top Amperage rating. The estimated time the battery will give you is 6/100x1950/33.3 = 3.51 minutes.
If you using ALL of your ESC (full throttle), you might see 6/100x1950/40 = 2.93 minutes.
WARNING: Time estimates herein do not account for the cutoff voltage required by LiPo batteries.

Not to interrupt your already fine work over the last year ... it's fascinating, informative, and useful ... but ...

may I humbly suggest Model Aviation March and April 2005, Selecting Electric Power Systems.

The Avistar:
wspan 59 in.
warea 602 sqin
wght 5 pound (80 ounces)
WINGLOAD (80/602)x144 = 19.14 ounce/sqft

To fly aerobatic, MA suggests between 60-100 watts/pound.
To fly a strong aerobatic plane, MA suggests between 15-25 ounces/sqft.
The aboveMA issues have more detailed information on these important issues.

Simply multiply the Avistar weight times your preference of watts/pound. This gives
a required 'mean' (or average) watts required. For the Avistar, my personal preference
is 5 pounds X 80 watts/pound = 400 watts. This is my 'happy plane' number.

Now select a 'happy battery'. Watts = Amps X Volts. The MA issues will explain
in detail how to do this. Without explaining, although the above posts should have
given you a 'feel' for it by now, I've selected a 4S2P 14.8 volt 4000mAh Thunder Power LiPoly.

Amps = Watts / Volts = 400 / 14.8 = 27.03 Amps required. to keep my 'happy plane' flying at 80 watts/pound.
Time 4S2P 4000 = ( 60 / 1000 X mAH / Amps ) = 60/ 1000 x 4000 / 27.3 = 8.79 min.flight
Time 4S2P 4000 full throttle = 60/1000x4000/40 = 6 minutes (doubtful ... the battery is likely to catch fire).
... the 4S2P likes only 20 Amps continuous ... so, some throttle management is in order ... unless you LIKE fires ...
WARNING: Time estimates herein do not account for the cutoff voltage required by LiPo batteries.

Either a 5S2P 18.5 volt 4000 or an 4S4P 14.8 volt 8000 will increase the flying time. Caveat: these
selections WILL add more weight to the Avistar, thus increasing the Watts above 400 and increasing
the Amps required to keep the plane 'happy' ... so, redo the calculations for either new battery choice
and see if you are happy with the performance.

Time 5S2P 4000 = 10 minutes at 22 Amps.
Time 4S4P 8000 = 15.44 minutes at 31 Amps.
WARNING: Time estimates herein do not account for the cutoff voltage required by LiPo batteries.

I've adjusted the Avistar weight according to Sport Aviators 5 pound (I'm suspicious of this low weight figure, although the 6 pound Graupner Taxi Cup II flies fine with a lot less motor and a lot less battery) flying weight in its online magazine. You WILL, of course, have to weigh your finished Avistar and add the motor wt, mount wt, and battery wt to be sure of the figures.

Last but not least, pick a motor to fit the realities which jump out of calculations such as above.

May I humbly suggest the Model Motors AXI 4120, 70 Amp rating, and the Jeti 40 Amp w BEC controller. It will work witha variety of planes from .25 to .60 ... although the slightly cheaper AXI 2826 (same controller) will work just fine with the Avistar and the 4000 mAh battery (4S4P 8000 is likely to overheat the AXI 2826). I am currently configuring a Hobbico NexSTAR, 6.71 pounds, with the aforementioned configuation and will probably go with the ThunderPower 5S2P 18.5 volt 4000 mAh. Next, however, I plan to do the Avistar ... so I'll be reading this thread as often as possible !!!

In all fairness, I should mention the Hacker C50 series ... they are fine choices for the above situations ... and one each mounted on the fenders of a VolksWagen, should get you to the SuperMarket quicker ... i suggest a 15x8 3 blade prop and a 70 Amp controller.

Thanks !!!

http://www.hobby-lobby.com/brushless_axi.htm
http://www.masportaviator.com/
Bonnie 20
... uses an AXI 2820/10, Jeti 40, and 8 cell NiCad 1700 (too small)
http://www.masportaviator.com/ah.asp?CatID=1&ID=39
http://www.hobby-lobby.com/bonnie.htm
Graupner Taxi Cup II
... this baby has me drooling and the flight videos are superb ... including a somewhat raggedy 'knife edge' ...
... uses an AXI 2826/12, Jeti 40, and a 3S2P 11.1 volt 4200 mAh LiPoly
http://www.hobby-lobby.com/taxicup.htm
The Taxi Cup has a listed flying weight of 6 pounds, thus a WINGLOAD of 23.15 ounces/sqft. This is a bit much for the listed 3S2P. Quite frankly, I would use the same AXI 4120 as above suggested for the AviStar and the NexSTAR ... with at least a 4S2P 4000 mAh.

HHH

Thanks for the details.

I have converted the Avistar with both a brushed system and a brushless system. I was just trying to see if this twin drive would work. The Jeti 30-3 has been my best preformer in this plane. It is currently in my Extra 300. I think I have fixed my MEC Superbox and motor and will try it later. It puts out 500 watts. It is all about experimentation!!

Experimentation for sure !!! What's interesting is how the performance of many of the midrange (say, 40 to 60) electric motors can be altered by the battery and the ESC. A .46 or a .61 has been benchmarked over the years and standardized for performance.

While electrics have been around for 30 years, all the NEW electrics, ESCs, and batteries have yet to be 'benchmarked' to everyones satisfaction ... vis a vis, so many changes in just a few short years.

I'm sure you will like the 500 watts on the Avistar ... i've reconfirmed the 5 pound flying weight (glo standard, but a target for electric) ... it should be quite peppy ... and very aerobatic !!! Make sure your ESC will deliver the 500 by multiplying the Amps X Volts !!! E.G., my Jeti 40 and 4S2P would deliver a 40 x 4 x 3.7 = 592 watts MAXIMUM ... good for take off of the 6.5 pound NexSTAR and more than enough for 423 watt normal flight. By now, i think you already know that ... just wanted to make sure you didn't forget ... ... now, as long as i don't rip the wings off during take off ... ...


PPS (several days later) ... i seem to have forgot you have a whattmeter ... ooops ... mea culpa ...

HHH


The Avistar flies great with the MEC system. I have tried it with 8 cells and a 14x10 prop and it flies good. With 12 cells and a 13x6.5 prop it flies good at 1/3 throttle and as fantastic at WOT. 444 watts @ 36 amps. Much better than the Jeti or brushed Endo versions. Best of all I used stuff I had and didn't spend anything.

Guys


This power system shown on my Magic is now on the Avistar with a smaller prop. It makes the plane a great windy day flyer.

The above system is run on 12 3300 mah nimh cells and a 13x6.5 prop or a 3S2P 4200 lipo and a 14x7 prop. GB is 5:1.