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Old 04-13-2010, 07:17 PM   #1
jombo
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Default my hk 250 , this thing is tiny

i have been looking for something smaller than the 450 and didnt want to spend a whole bunch if i didnt like it so i gave the hk250 for 30.00 a shot. this thing is almost all metal except the head and the part of the seasaw. the tail is plastic but the tube has a hole in it and the tail locks into it. from what i have seen it has all bb everywhere in the head and tail.
but now for the twist , i have some fixed pitch blades so i dont need the ccpm radio just a basic computer radio and save the 7c reciever for the 500 and 450. has anyone else tryed this , i hate the 4 channel fp with the motored tails and they always died at the worst time. this way i can run a lower head speed and bring it to the park with me. i am hoping to get this thing built by next week to try it out, not heavy in 3d so that is not a problem, i just want something to have fun at the park with the kids and maybe have others here (if they show up at the field with there planes) a try.
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Old 04-29-2010, 03:21 PM   #2
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been slacking on this as i havent had alot of time, here it is about to put the arms on and to level the swash , and some pics with the fixed pitch blades
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Old 04-29-2010, 03:26 PM   #3
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That's kind of an interesting idea.
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Old 04-29-2010, 05:05 PM   #4
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Thank you but it's not a original idea. Someone on rc groups made one already and flys great , I wish I googled searched it first as I could of saved some time looking things up . I needed to use a low kv motor for the blades so I needed to know what watts a brushed 380 motor does and the rpm, I ended up using the same 2400 kv motor on 7.4 v lipo lol .
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Old 05-10-2010, 01:50 PM   #5
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i got it almost done , i tryed the falcon 40 blades but since they use a plastic spacer for the mounting hole i used some plastic spacers i had and fit perfectly. set the swash, servos , esc , head , and had to test it out . i only had 1/5th throttle just enough to spin it up ,wow this will take off for sure at 1/3 throttle sweet
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Old 05-13-2010, 02:00 PM   #6
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got a small problem with the setup , it will take off on 2 cells but it spins like there is no tail . i lowerd the pitch on the blades to 0 but it still spins , alot less though. this is with no gyro installed i am using it old school and i dont have a gyro avalable yet :o . anyway just asking questions because right now not sure what to try........ lower the pitch more , up the motor to a 4400kv instead of the 2400kv should i clip the falcon 40 blades alittle as it may be too much for the tail to handle ? not giving up yet as i still have a spare kit on hand just in case this gets trashed in the testing stages.
anyone got any suggestions i can try
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Old 05-13-2010, 02:41 PM   #7
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I was wondering how that would work but thought maybe a gyro would sort it out.

Is the tail overpowering and spinning the heli? or underpowered due to lack of speed at the tail.

If walkera can have a fixed pitch heli (4#6) with a tt driven pitch tail, then there has to be an answer for getting this to work.
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Old 05-13-2010, 03:56 PM   #8
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it seems under powerd , i have the stick all the way to the left and on startup its fine then about 1/2 throttle it starts to spin , i can get it off the ground on the spin but i dont think it will fly well . i neet to try the faster motor , i will see if that helps or make it worse
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Old 05-13-2010, 05:45 PM   #9
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Quote:
Originally Posted by jombo View Post
it seems under powerd , i have the stick all the way to the left and on startup its fine then about 1/2 throttle it starts to spin , i can get it off the ground on the spin but i dont think it will fly well . i neet to try the faster motor , i will see if that helps or make it worse
Seems like it would make it worse or no real change. The tail will still be geared the same.

I think you were on the right path on trimming the main blades, don't think you could get much larger on the tail.
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Old 05-13-2010, 06:41 PM   #10
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i will give that a try , it came with 2 sets of tail blades , a lonf set and a shorter wider set . i will change them out and see what that does
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Old 05-13-2010, 06:48 PM   #11
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Cut your main blades down, they are far too large.
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Old 05-13-2010, 07:12 PM   #12
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you are right the blades are too big, i just tryed the heli with the stock blades and it hoverd fine and the gyro i put on for the time being off the 450 is wagging hard , before it would just spin lol . i think i spent too much time today on it tomorrow is another day . i will cut about the size of the stock 250 blades and go from there, also the bigger tail blades made a small difference too .thanks guys for the help
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Old 05-13-2010, 07:46 PM   #13
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I'd personally cut the blades a few mm at a time until you get the desired mass and headspeed.
It's pointless cutting them to the same size as the stock blades as the lift characteristics will be totally different.
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Old 05-13-2010, 09:07 PM   #14
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i got them cut right now to almost the lenth, width of the stock 250 blades and its still spins , i think this ia a lost cause. i just checked the size of the falcon 40 tail and its big compared to the 250 tail , almost the size of the 450 tail. and now the belt broke , i dont see this working with a 250 size maybe a 450 but not 250 .
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Old 05-13-2010, 11:28 PM   #15
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Quote:
Originally Posted by jombo View Post
i got them cut right now to almost the lenth, width of the stock 250 blades and its still spins , i think this ia a lost cause. i just checked the size of the falcon 40 tail and its big compared to the 250 tail , almost the size of the 450 tail. and now the belt broke , i dont see this working with a 250 size maybe a 450 but not 250 .
The 4#6 walkera is a 125 size heli with the same set up.

Try trimming more blade but not just length.
Maybe you can find a different blade with less pitch. Sounds like you just need to find the right balance of headspeed and lift to allow the tail to work.
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Old 05-14-2010, 11:22 AM   #16
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here is where i am at, i started with and i have cut the blades down alot and it still spins . the 450 tail hits the ground so thats a no, and faster motor is also a no since with the 2400k i can hover and fly with the stock blades . i have alot of fixed pitch blades from coax helis and will try them out , or look into the walkera 180 d blades . first things first new belt.
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Old 05-18-2010, 05:52 PM   #17
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got the new belt from amain and i think it was the belt slipping before , now the tail holds perfectly . now for the bad news , i must of cut the blades too much as now it wont take off . well no worries i got plenty of fixed pitch blades to try .

stay tuned........
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Old 05-18-2010, 06:52 PM   #18
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put the new blades on new belt , got the green light to go for it and found a few things out .
1- low head speed will give me less tail authority
2- a higher head speed makes the tail locked in with no input from me
3- to achieve more head speed i need to give it -9 pitch instead of 0 , if in the + it will be too slow and will spin .
4- it needs more motor , got the 4200kv comming soon or could probably go with a 3 cell lipo
the video is a bit dark but you can make out the pitch i put in the radio
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Old 05-21-2010, 10:17 AM   #19
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i am giving up on this for now , i got the new motor in and it did fly but i also stripped the main gear because of the motor mount . i used a GT metal motor mount, the plastic version 250 will not work with it sio i used 4 screws instead of 6. then i forgot to lower the pitch on the radio to -18 and left it at+5 so it spun but was controllable so if i lower the pitch and to -18 or -11 it may work . so right now the weather is beutiful and dont want to waste anymore time fiddling with it , time to go to the field and have some fun.
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Old 05-21-2010, 10:38 AM   #20
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Quote:
Originally Posted by jombo View Post
i am giving up on this for now , i got the new motor in and it did fly but i also stripped the main gear because of the motor mount . i used a GT metal motor mount, the plastic version 250 will not work with it sio i used 4 screws instead of 6. then i forgot to lower the pitch on the radio to -18 and left it at+5 so it spun but was controllable so if i lower the pitch and to -18 or -11 it may work . so right now the weather is beutiful and dont want to waste anymore time fiddling with it , time to go to the field and have some fun.
Maybe an Align gear will be stronger?

You'll get it eventually, taking a break can be a good idea.
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