Home › Forums › Free Flight › Electric Free Flight › Geef 250 for E-36
- This topic has 15 replies, 3 voices, and was last updated 16 years, 1 month ago by Timer Guy.
01/25/2007 at 11:11 pm #40567
Geef 250 for E-36. GWS IPS 4.8v with Smoothie timer. Weight 145 grams
I hate adding weight to models!. Have 8×4 folding prop ordered. Batteries are 100mah from BP Hobbies.
01/26/2007 at 12:03 am #43855Jim JenningsParticipant
Ed, I think that the model looks great! Have you flown it yet? I agree with your comment about weight. I think that we should have a wing span restriction or a minimum weight ,not both. The wing span is easier to police.
01/26/2007 at 12:20 pm #43856
Jim, have not flown it yet only hand glides in the back yard. I don’t have a good place to fly here, only a small field at the local power plant that has a lake and a lot of chain link fences. If I can get a day with no wind I might give it a try, otherwise it will be Atlanta or Pensacola.
Ed01/30/2007 at 6:03 pm #43857
Great looking, Ed. What holds the battery hatch closed? I was looking for a tiny magnet but do not see it. What sort of current draw and RPM are you seeing? Is that the 8×4 EP prop? Can you not get in some test flights with a shortened motor run?
01/30/2007 at 8:45 pm #43858
Hank, the hatch is a tight fit, so it will stay closed but I add a piece of scotch tape for insurance, not too high tach but it seems to work. I don’t have a tach so no rpm info. The prop is a 10×4 but I have a 8×4 folder on order. The 10 x4 is too much prop I would guess. Sense I am a mechanical type and not an electrical guy, I have a dumb question: Will I get the same rpm from a 4.8v 400 mah battery pack as I would from a 4.8v 600 mah pack, the 600 mah pack would just last longer between charges, or am I missing something?
Ed01/30/2007 at 8:56 pm #43859
Ed, neither a 400 or a 600 mah pack are allowed in E36. Besides, the weight would kill you. The largest cell allowed is 190 mah from Sanyo.
But to reply to the question, there will not be much difference at all between a 400 and a 600 with the small E36 motor you are using. Certianly not in the 25 second run time. However, there will likely be a differece between the 100 mah you are using (as I recall) and the 190 that is allowed. The reason being is you are much closer to the limit of the battery. And, a NICAD “should” be better than a NMHD for this application. How much is subject to discussion.
You are no doubt over loading the motor (4:1 gearing?) with the 10 inch prop.
01/30/2007 at 10:43 pm #43860
Hank, thanks for the reply. But now I am really confused. I thought the rule was for a single battery; i.e 1.2v 190mah x 4 batteries to equal 4.8v 540mah. The two battery packs I have are labled 400mah 4.8v BP NIMH at 36 grams and HBZ 1010 NI-MH 4.8v 600mah at 56 grams. Are these battery packs illegal for E-36?
01/30/2007 at 10:54 pm #43861
ops, sorry about the math should have read 1.2v 190mah x 4 equals 4.8v 760 mah.
01/30/2007 at 11:05 pm #43862
ED, you add voltage if the cells are in series, but current capacity (Mah) is what ever the weakest cell can supply. So, four 190 mah 1.2 volt cells in series (connected plus to minus for all four) is 4.8 volts (nominal) and 190 mah. If you should happen to put the four cells all in parallel (plus to plus and minus to minus for all) then you have 1.2 volts and 4X190 mah.
Got it? If you put three 190 mah and one 150 mah battery in series, you have a 4.8 volt 150 mah battery.
Sorry to tell you, but the two batteries you have are no nos for E36. Plus, they weigh a ton compared to four 190 mah cells. You will not get off the ground. IMHO
Hank (MSEE a century ago)01/30/2007 at 11:09 pm #43863
This error should be obvious, but when you connect four cells in series, you only connect three cells together. The first plus and last minus are the output for the combined battery. I figure someone would call me on this.01/30/2007 at 11:20 pm #43864
yeap, I got it! so I guess I am going to have to find some batteries. If the new batteries weigh less than the ones I have now I guess I’ll have to add some weight to get to the 150 gram rule.01/31/2007 at 12:56 am #43865
Look for Sanyo 190 mah N cells. Nicads. I found them at an on line place in Dayton. Name is not in my brain file.01/31/2007 at 1:47 am #43866
Ed, I could not lay my hands on my 190 mah N cells but some 150 mah cells weigh 29.5 grams for four of them less the interconnect solder/wire and the external wires connector.
You will not find a made up pack of four cells. You will need to put one together yourself. Or, send the cells and your connector to me and I wll solder it up for you.02/01/2007 at 12:03 am #43867
Ed, this is what the Sanyo 190 N cell looks like. Four of them weight 34.5 grams. Without interconnects and wire plus connector.
02/01/2007 at 12:40 pm #43868
Thanks for the info Hank, I also found some 190 mah battery packs at SR Batteries.
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