Last DOWN XXXL v3 - 3.6m wingspan power setup - RC Groups
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Jul 01, 2008, 06:25 AM
Snowboarder
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Last DOWN XXXL v3 - 3.6m wingspan power setup


Hi there !

I just bought the latest and just released Last Down 3XL V3. It's really cheap and will enough for me I assume I'll go with a High Aspect from Art Hobby when I'll get some serious gliding skills The UPS shipping was offered ... Seems to be a good deal. I will let you know.



Specifications
wingspan: 3,60 m
length: 1.44 m
weight: 1650 gs (empty)
airfoil: E-205

Expensive Stock setup : cause price is in euros
AL-3548 combo with 60 A controller
Well suitably for e-sailplanes (to 3000g) and e-airplanes (to 2200g).
Length 48 mm, diameter 35 mm, weight 170 g, shaft diameters 4.0 mm.
Current 35-50 A, 630 watt, 900 Upm/V.
Recommendation: 3S LiPo 11x6-13x6,5 thin-e-prop or folding prop. 4s LiPo 11x6-11x7 thin-e-prop or folding prop.


I'm wondering what alternative "great" power setup could I put in this bird ? I'm open to A123 too. I already have a Turnigy 60A ESC. I also have a Medusa MR-028-040-2500V2 ... but really don't know if I could use it.

Let me know what you would do If you were me.

Much appreciated as usual

Cédric
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Jul 01, 2008, 07:51 AM
pigs will fly!!
Hi there Cedric

I have Scorpio Condor voodoo which is similar to the last down except mine is 3.2 m wing span, I use rimfire outrunner 42-50-600 which weighs 200 gr and drives a 17x9 folding prop with a 3s 3700mah lipo and draws aprox 35 amps in static tests, I use a hyperion ESC with switching BEC which drives the 6 servos and receiver to save weight.

http://www.electrifly.com/powersyste...ire-42-50.html

If my memory serves me well, my empty weight for the airframe was close to 2 kg and my all up weight ready to fly is 2.7 kg. the last down has had several updates and the last one is the V3, like the one you have purchased, and in theory should be lighter than my scorpio condor voodoo.


my flights tend to last a minimum of 45 min and thats with hardly any thermal activity (I fly next to the beach ). and my model climbs at 60º angle with ease, so a 10 to 15 second motor run gives you plenty of height to search for thermals.

The lighter you build your model the less power needed to fly !!!

I hope this helps

Regards

Joe Rubido
Jul 02, 2008, 04:49 AM
Snowboarder
Hi Joe,

Thanks for the reply. I'm willing to get a better power setup for the 3.6m with maybe A123 .

Any other advises?

Cédric
Jul 02, 2008, 08:46 AM
pigs will fly!!
Hi Cedric

The last down with an eppler 205 wing profile and 3.6 m wingspan and lots of wing area is going to be nice relaxing glider to fly, but in my opinion its not glider to overpower.

With a glider you want to use a large diameter prop to provide thrust, I did a fair amount research last year when I built my condor voodoo as to which motor would be most suitable and at the same time good value for money, if you want more power with efficiency I would suggest you look a geared inrunners, but the price for a geared inrunner will probably be above 200€ and this rimfire brushless will cost you less than 70 $ + shipping.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLWV2

Here is a link to video of a condor Voodoo like mine except he runs a 16x10 prop and ten cells nimh, and his model is heavier than mine as a result, look at the video and the rate of climb he achieves. I would expect similar performance from a 4s 123 pack

http://www.youtube.com/watch?v=rJjc3icgvUE


I hope this helps

Regards

Joe Rubido
Jul 02, 2008, 10:41 AM
Snowboarder
OMG, the climb rate is really slow ! I want it to clim 60° !

I already have a Medusa 28 Afterburner v2 2500 kv on my Desk.... Maybe a gearbox could be a good choice.

Cédric
Jul 02, 2008, 02:29 PM
<- Balsa flies better ->
wolw's Avatar
Hi Cédric, Joe

I have a 3.2m T2M/Scorpio Condor too.

Joe, any problem balancing it with a 200g motor and 3S ?
I think it climbed out just fine for a thermal.

Peter
Jul 02, 2008, 02:48 PM
Snowboarder
Hi Peter,

Nice to see you again Your advices always worth.

What servos are you using on your Condor ? 6 servos are requested isn't it ?

I was considering three motors :
- the one advised by Joe

- TGY AerodriveXp SK Series 35-42 1000Kv / 605w
http://www.hobbycity.com/hobbycity/s...idProduct=7125

-a Scorpion motor that may perform better : 3032-10
http://www.innov8tivedesigns.com/pro...products_id=82


Cédric
Jul 02, 2008, 03:08 PM
<- Balsa flies better ->
wolw's Avatar
I would guess the 35-42 is way too light, there of my question if it was easy to balance it with a 42-50 and 3S, there's an review somewhere (Hobby-Lobby ?) using an AXI 4120.

I haven't looked into servos just yet, there's a ton of information in the "making the condor go vertical thread". It all depends on if you want to be able to use "crow" on landings, if not I guess something like the Vigor VS-3 would do. There a lot more stress on the surfaces using "crow", but when I think of it I use the VS-3 on my Svist and they're holding up just fine.

Peter
Jul 02, 2008, 03:34 PM
Snowboarder
Peter, I'm gonna post my #7 message on the condor thread.

I'll have the plane tomorrow, just want to be sure to buy the good setup.

Cédric
Jul 03, 2008, 02:58 AM
pigs will fly!!
Hi there guys

Wolw my condor voodoo was not easy to balance, this model is known for being a bit tail heavy, no doubt a problem related to the fact that the model was probably designed to carry nicads/nimh cell packs.

In order for the model to achieve the correct CG, I had to drill holes in the rudder and rear stab to loose weight, these in the condor are solid balsa, and in my case way to heavy.

I had consired making a built up rear stab and rudder, in order too loose a bit more weight, but didnt need to after lightened the tail.

As for what servos to use, I used 5 robbe FS 70 MG, these are 20 gr servo with metal gears for wings surfaces and rudder and a robbe FS 60 10 gr mini servo for the elevator ( fitted inside the tail ).

I hope the last down v3 comes with better weight distrubution than my scorpion condor voodoo.

Regards

Joe Rubido
Jul 03, 2008, 03:03 AM
Snowboarder
Joe,

I'm gonna carry mine in the next hours. Will do a video of out of the box and comments the weight.

I'm still wondering what servos to put in this nice bird

Cédric
Jul 03, 2008, 08:16 AM
<- Balsa flies better ->
wolw's Avatar
I had HXT 42-63 in mind to mine, ~280g up front should help and option to run both 3S & 4S.

Peter
Jul 03, 2008, 08:47 AM
Snowboarder
Peter,

I was planning to buy four HS-82MG for the wings and HS-85MG for elev and rudder.

HS-85MG : $30.99 x 2 = $61.98
HS-82 : $20.99 x 4 = $87,96
Total for servos : $149,94

+ Scorpion 3032-10 (823kv) : 89$
http://www.innov8tivedesigns.com/pro...products_id=82

Do you think I should get theses or better the hobbycity copies? and where to buy the HS

Cédric
Jul 03, 2008, 08:58 AM
<- Balsa flies better ->
wolw's Avatar
The motor is great but at kv823 it's more of a 3S motor if you want to use a decent prop.

Hitec servos are good but at a price, I'd suggest HXT9320MG or HG-D250(I haven't tried these myself yet, I have them on backorder though for my Graupner Extra 300).

Peter
Jul 03, 2008, 09:01 AM
Snowboarder
(updated)

Thanks Peter, It seems the HXT 9320MG is a top notch servo and even better than the HS.

0/ I'm hesitating between theses two servos now :

Digital high torque bearing servo 15.7g/2.2kg/.09sec
http://www.hobbycity.com/hobbycity/s...idProduct=6607

HXT 9320MG 20.2g / 3.8kg / .15sec Precision Servo
http://www.hobbycity.com/hobbycity/s...idproduct=3609

Any idea of the "best" ?

1/ I'm gonna also buy the same BEC as I bought on my Wilco : TURNIGY 3A UBEC w/ Noise Reduction
http://www.hobbycity.com/hobbycity/s...idproduct=4319

2/ I may add some MPX connectors do you think the hobbycity one worth ? and also some servo wiring stuff ... As I'm gonna need some meters .... wich one do you recommend ? I need quality servo wiring as it's really long wires on the wing.

I don't know which one to buy :

Flat 22AWG servo wire 1mtr (R/B/Y) or
Flat 26AWG servo wire 1mtr (R/B/Y)

3/ Lipo : ZIPPY-R 4150mAh 21-35C 4S1P
http://www.hobbycity.com/hobbycity/s...idproduct=6523

4/ I'm also gonna get the Multiplex Blizzard (tomorrow I presume), Which servos can I put inside @ Hobbycity. As it's a foamy hotliner, I don't want to put 9g servos but I would prefer metal gears. Which one would you recommend for this bird (they ask for HS 55)?

Thanks !!!!!

Cédric
Last edited by okayplayer; Jul 03, 2008 at 02:40 PM.


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