|May 22, 2007, 02:55 PM|
No problem... What the hack is XD?
Check this guy's e-bay.es store he sure might find something for you.
And another warning: when you will go shopping for batteries, don't buy ones
AA- R6 size that are for use in digital cameras, they are not capable of higher current. I've heard many begginers complaining that plane don't want to fly...
and the cause were those nice capacity cells. Buy 2/3 A size GP, KAN, CBP...nothing else. They are robust and can be fast charged with current equal 2 times capacity...
we say charge with 2C...
cells 1200mAh... charge with 2,4A
still... if you want go brushless...brushless... motor is 10 times more expensive than ordinary speed 400. , ESC for brushed motor will be at least 2 times cheaper than for brushless...If you & money friends... than no problem
|May 22, 2007, 03:55 PM|
Joined May 2007
So those high capacity batteries don't do a great job, that's a pity, when you say 2/3 A size you refer to 28.5mm Length and 17mm diameter ones?
As you said Kan 1100mAh, in the description says hight current cell (20 Amp) among the NimH cells,19g,length 28mm,diameter 16,5mm, could they be those ones? Or maybe LRP VTEC 1400, New 2/3 powercell , same size as KAN 1050 , extremy high current ( above 20 A ) now with 1400 mAh. Am I lucky??
I'll have to ask at shops here, Thanks once again, money and I are not friends XD just have some bucks to spend and I always wanted to have something amazing like this! And well, i'm a bit bored XD What about this ESC?
Until next time!
|May 24, 2007, 08:45 AM|
Joined Sep 2006
While we are on the subject of battery packs, maybe somebody can advise me on the best option for my setup
graupner speed 400 - brushed motor
6 x 3 graupner folding prop
medusa technolgies 30 amp esc
Im looking for nimh or nicad packs since i only have a charger for those types, obviously i want to keep the weight down but i also would like the pack to give good flight times.
P.s. im not the most experienced in electric flight, so please keep things simple
|May 24, 2007, 09:19 AM|
I don't know where you are located, but I am guessing by the nickname and salutation that you are in Europe. It would help to know so we can point you in the right direction on where to purchase it from.
First I must admit that I have not built a Guppy and not proclaiming to be an expert on this particular model, but have been following this thread. However I have built and been flying a friendly Elexaco competition the past few years that limit the motor, prop, and battery to a Graupner 7.2V, Guenther prop, and 7 cell battery. I do change out the prop and motor for sport flying though to a 6x3 folder and a 6V Graupner. (my plane is in my avatar or HERE )
So for your scenario I would recommend a Graupner 6V with a 7 cell NiMH battery. I have noticed a big difference in using the Cheapbatterypacks.com CBP750's, but the equivalent is the KAN700. The cell performance is pretty good and has a relatively low series resistance. My recommendation on battery pack a 7cell KAN700 in a 4x3 configuration. The 3 cells stacked on top of 4 give you flexibility in shifting the pack for and aft for ballancing because of the shorter pack. The pack should weigh around 3.5oz or 100g. From doing a search on this thread it seems people are able to get the CG in a workable range with the pack weight. This should give you a nice lightweight pack for quite a few climb and glides with good thermaling ability(very fun! ). If you have built it lightweight or flying on a windy day or you just want to increase your flight times with some weight penalty and penalty in soarability on a light wind day, you could use an Elite 1500 cell. This pack would weight about 5.8oz (165g), so you'll have to determine if your plane would be too heavy with this weight. I have used both of these cells on small brushed applications and speak highly of them. They are not being pushed hard and should give a reliable cheap solution. Hope this helps.
If you do a search on this thread you will see my recommendation is in line with what everyone else is using, but I understand if you are new to electrics you want a definitive answer of what works and what doesn't.
|May 24, 2007, 08:51 PM|
Box Elder, SD
Joined May 2002
Hope I don't get in trouble for this but in the classifieds section is a Guppy kit for $80, I'll take $75 and that includes shipping.
|May 25, 2007, 08:08 AM|
If you've got a 7.2V speed 400 I'd switch to 8 cells instead of 7. If I remember right you can even use 8 cells with the 6V motor and get great power but the efficiency and motor life aren't great.
Even if you live in Europe (as I do) it's as quick and possibly cheaper to buy from www.cheapbatterypacks.com in the US. They're shipping rates are pretty low especially if you're buying 2 or 3 packs (which is worth doing especially if you're going the lightweight route).
If you want to do this go to the left hand menu and select Packs > Custom Packs
Pick the KAN700 or Elite 1500 cells
Offset brick is the configuration Scott suggested for the KAN700 cells.
I'd pisk 18AWG wire
Whatever connectors you use (if they're on the list!)
I just had a look out of curiousity and it should cost:
KAN700 (7 cells) $17.50
KAN700 (8 cells) $20.00
Elite1500 (7 cells) $21.70
Elite1500 (8 cells) $24.80
I've ordered a few times from these guys and never had a problem.
Hope this helps
|May 25, 2007, 04:40 PM|
A 6v SP400 on 8 cells driving a 6 x 3 prop should last 100 flights easily. This has been my set-up on numerous models for the last eight years. I also time them up which improves the performance but the life comes down to about 70 flights...
I still think that for many small models it's still a very good set-up.
|May 26, 2007, 08:55 AM|
Joined Sep 2006
Guys thats fantastic advice, well i think im gonna order a couple of packs off cheapbatterypacks.com
One question, the elite 1500 , will that give longer flight times than the kan700???
i know it depends on how much you use the motor, but roughly which one would be best.
|May 26, 2007, 09:08 AM|
E-flite 400 BL motor installation
Here is yet another BL motor installation for the Guppy. I'm using an E-flite 400 (920kv) outrunner. It's small (56g and 28mm dia.) and worth about 140 watts. Should do well with a 9"x7" folder on 3S. I like this motor becauses it lends itself to an installation which has the firewall and the wires on the aft end while having a 3.175mm (1/8") shaft on the other end for collet type folder/spinners. Hasn't been run yet. Still a lot of sanding to be done.
I'm making a running asumption that cooling is not that important considering the short motor runs. Let me know what you think.
ImagesView all Images in thread
|May 27, 2007, 07:03 AM|
Joined Aug 2005
133% of Guppy
First of all, I would like thank you Mitja for your Guppy. This thread inspired me, so I resize your Guppy to 2 m wingspan. It flies really great!
I changed a little construction and airfoil to AG35.
Wingspan: 202 cm
AUW weight: 1420 g
Motor: HIMAX 3522-0700
Prop: Aeronaut CAM 12x8
Power: 3S1P 2200 mAh
1200 G of static trust
4xHS-81 + BEC + 40A reg.
Photos with temporary canopy
|May 27, 2007, 09:59 AM|
If we ignore the power required by the radio (this is most relevant for longer thermal flights) the KAN700 will give roughly 4 minutes of motor run and the Elite1500 will give a little over 8 minutes.
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