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Nov 02, 2012, 11:13 AM
1 can never have 2 many planes
chambo88's Avatar
Thread OP
Build Log

pond racer "PR-1"

Since the time for me to leave germany is unfortunately fast aproaching. I have been looking into continuing building with epp when i get back to australia.. since the possibility now exists, i have decided to get some plans together for possible models when i get back. one will have to be the beautiful pond racer.

i'm planning on it having a wingspan between 1.-1.4m. but having such an interesting shape and configuration. i will attempt to build a much smaller depron version to try and figure out the strong/weak points. And most imortantly the cg relative to the root wing chord.

the depron version should be no bigger than 800mm..

700mm depron version specs:

wingspan: 700mm
AUW: 274g
x2 2300kv 20g brushless outrunner (B/O) with 6x4 prop
x2 10amp esc
x4 9 g servos (elevator and x2 aileron)
x1 or 2 800mah 2s lipo

800mm epp version specs:

wingspan: 800mm
AUW: 530g
x2 1700kv 24g brushless outrunner (B/O) with 7x4 prop
x2 20amp esc
x4 9 g servos (elevator and x2 aileron)
x1 1300mah - 2200mah 3s lipo

not plannin for it too be a rocket, but simply a learning platform for its larger brother.

the brother on the other hand... well.... thats a different story..

pond racer #2 1-1.4m version

1400mm epp version specs:

x2 1100kv 3530/14 73g B/O with 9x8 props or x2 1000kv 3536/8 102g B/O with 11x8 props
x2 40amp esc
x4-5 9g servos (elevator 1-2 servos, ailerons, rudder)
retractable undercariage
x2 2200mah 3s, one in each pod or x1 3000mah 3s located in the cockpit (will depend on the weight and wingloading)

here are a few pics for those who dont know its gorgeous shape

hopefully plan to start building on monday or so.. have a few things to do, those who follow my threads will know what im talkin about
Last edited by chambo88; Nov 27, 2012 at 03:51 AM. Reason: updated large scale power system
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Nov 02, 2012, 03:27 PM
registered foam addict
chara's Avatar
great project! I' with you
Nov 02, 2012, 08:43 PM
Krued Up
snolord1's Avatar
no will look wicked
Nov 03, 2012, 08:56 AM
Registered User
eaticus's Avatar
Some reference for you:

Nov 03, 2012, 11:28 AM
demondriver's Avatar
Great project Chambo!, looks like a starwars Pod racer with props!

this is gonna be great subbed up!
Latest blog entry: RC 737 Max 7 Maiden flight!
Nov 03, 2012, 02:29 PM
Registered User
perttime's Avatar
Are you designing it/them from scratch, or starting from an existing drawing?
Nov 03, 2012, 02:55 PM
1 can never have 2 many planes
chambo88's Avatar
Thread OP
Originally Posted by perttime
Are you designing it/them from scratch, or starting from an existing drawing?
will be goin from a 3 view cad drawing.. but designing the internal specs for the electronics and structural supports myself.
Nov 03, 2012, 02:56 PM
1 can never have 2 many planes
chambo88's Avatar
Thread OP
Originally Posted by eaticus
cheers dave!

some good reading material there. interesting history surrounding this bird too.
Nov 03, 2012, 04:40 PM
1 can never have 2 many planes
chambo88's Avatar
Thread OP

pond racer spinner prop dilema

here is a question, regarding the size of the prop respective to the size of the motor and spinner used.. the suggested prop size for the motor i plan to use on the larger version is around the 5x5 range. but i know from experience i can use a 7x4 prop as long as full power isnt used the whole time..

but my question is... if a large spinner is blocking perhaps 4-5 inches of airflow to the prop, would that reduce load on the motor because the prop isnt doing as much work? would it therefore allow the motor to spin an even larger prop to bring load back up? for example a 10 inch prop.. the increased amount is assuming the difference in sheltered prop is simply added to the total lenght so that the same 7 inches of prop is exposed to airflow. im aware that the relative speed of the prop blade increases with diameter, so perhaps a 8.5-9 inch prop could be the maximum as well, taking this into account..

anyone have any thoughts??
Nov 03, 2012, 06:24 PM
looking up, down under
scruffy1's Avatar
Originally Posted by chambo88

anyone have any thoughts??
buy yourself a watts up meter

that way you can experiment with any combination you wish and find out just how close to releasing the magic smoke you might be if you push the throttle; great for different batteries / esc's and prop combinations so you don't get to experience destructive testing as the standard

believe me, it's the best investment you can make with electrics

and as for balance, i would think that despite the slightly unconventional structure it is a pretty standard tractor prop monoplane, so i'd think possibly a conservative cg of 25% wing and move it back with experience
Nov 03, 2012, 06:39 PM
1 can never have 2 many planes
chambo88's Avatar
Thread OP
Hi scrufy1, I do have a watt meter. I use it before any first flight of any plane so I can determine flight times and so on. Just wanted to see if anyone had anyone experience in the matter. thanks for your input!
Nov 04, 2012, 08:41 AM
Registered User
Prop power absorbed is proportional to the diameter to the 4th power.

No Spinner
Power ~ D^4

With Spinner
Power ~ (Prop D)^4 - (Spinner D)^4
Nov 14, 2012, 05:35 PM
1 can never have 2 many planes
chambo88's Avatar
Thread OP
ok so after a long time waiting due to other projects and my plans thread... finally managed to cut out the pieces of the racer 2nite put all the pieces and electronics onto the scales and she came out at 267g RTF. thats including hot glue, battery and all. keeping in mind the motors have 300g of thrust each. this will be a little missile. hehe

other thing on the to-do list is i want the epp 1400mm version to stand out.. paint scheme wise.. throw me ideas please.. was thinking something along the lines of the attatched pic.

so throw some pics up and ill pick my favourite 3, make up a skin of the schemes in gimp and project them onto the model pond racer i have on realflight6.

will then post the pics from the sim and let you all see and decide which one i will choose

was thinking something along the lines of these v v v
Nov 16, 2012, 04:21 AM
1 can never have 2 many planes
chambo88's Avatar
Thread OP
ok so here are the pics of the depron mini "test" version

auw is 270g
wingspan is 700mm
battery 800mah 2s

i know it looks a little slapped together.. but i want to see how she flies before i go and put a lot of effort into it..

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