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Old Jul 25, 2012, 04:45 PM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
Quote:
Originally Posted by jspcrepair View Post
I am going to get an MJX F45 soon
DH9104
Tail motor 2.99 amps full speed off 7.4v 1300mah Li-Ion stock battery.
Main motor 5.72 amps full speed off 7.4v 1300mah Li-Ion stock battery.
Non-motor load = 23ma = receiver and white floodlight LED (Transmitter turned off)
Receiver only = 16.1ma (Transmitter turned off)

Buy MJX F45 and an extra F45 receiver board. Put the F45 receiver board in the DH9104, use only three channels and use existing servo. That puts the DH9104 on 2.4GHz with the F45 transmitter. Then use the extra unused throttle channel to drive an ESC for brushless main motor. Later add aileron servo to the DH9104.

Get an 11.1v ESC that has a 5 amp BEC (UBEC is better). Set the BEC to 6.0v and use it to replace the 7.4 volt battery. Then run the DH9104 from an 11.1v LiPo.

Or instead of the 5 amp BEC, use a string of six 5 amp power diodes to drop the 11.1v LiPo voltage to (11.1v - (6 x 0.6v)) = (11.1v - 3.6v) = 7.5v to replace the 7.4v battery to run receiver, servos, and tail motor.

May be better to use a 1.5 amp BEC at 6.0v to run receiver and servos and leave only the tail motor fed from the diodes to allow a course adjustment for tail motor speed..


11.1v LiPo (+) ---- Powering ESC, BEC, Brushless motor
!
! ------11.1v
D
!-------10.5v
D
!-------9.9v
D
!-------9.3v
D
!-------8.7v - for faster tail motor
D
!-------8.1v - for faster tail motor
D
!-------7.5v to tail motor (+)

D = Power Diode 0.6v 5 amp or higher amps

The F45 guys running a Brushless main motor would rather use just an 11.1v LiPo to power everything. Gobs of power, but the brushed tail motor (on a separate 7.4v LiPo) can't keep up with the overpowered .main motor. With the above diodes, all runs off one 11.1v LiPo and the tail motor will track the 11.1v LiPo as it wears down. If the tail needs to run faster, use the 8.1v diode tap.
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Old Oct 16, 2012, 10:44 AM
Brakes? Who Needs Brakes?
United States, WV
Joined Jun 2012
36 Posts
Everything Is Fine Now!

Hi again...
After all my Tail Rotor issues and the main motor going out, I finally ordered the MJX F45 parts for testing in the DH9104.

I ordered from TopsToys but that was a mistake as I never got my order from them and had to get a refund... So, I re-ordered from RC Roanoke and got the parts.

I got the MJX F45 Main Motor and it works great!
A little more lift and a bit more torque so I may not have to worry about it failing so soon.

I bought a complete MJX F45 Tail Boom set because I wanted to see how close everything compared to the DH9104 Tail Boom and here is what I found.

1) The Boom Set may work on the DH9104 as a complete replacement because there is only a mere 3/8" to 1/2" difference (slightly shorter than the DH9104 Tail Boom). The Tail Rotor Blade will pass the Main Rotor Blade by about the same distance: 3/8" to 1/2".

2) The Tail motor does not turn in the same direction as the DH9104. This causes the DH9104 to spin out of control immediately upon turning the Remote Controller on. ** To fix this: the Blue and White wires had to be changed around (either in the plug or on the motor itself).

Both MJX F45 Motors will and DO work great in the DH9104 and seem to have a bit more power or at least Quality so they may last considerably longer than the original DH9104's.

QUESTION:
Does anyone know how to Remove/Replace the Tail Gear in the Gear Box of the MJX F45 and DH9104 (without damage)?

These gears are installed the same way but the Hex on the facing of the MJX F45 Tail Gear is slightly smaller than the one on the DH9104 and the tail rotor blades will not interchange on the gear mounts.

The reason I ask this is because the MJX F45 Tail Housing is built much better and has much better ventilation along the sides of the tail motor. The DH9104 Tail Housing does not have quite as good a design and I would like to use the MJX Tail Housing on the DH9104 Boom.

*** UPDATE ***
I found out how to remove the gear without damage -- But --
The MJX F45 Tail Gear is slightly larger in diameter than the DH9104 Tail Gear so that won't work.

Instead, what I did was mounted the entire MJX F45 Tail Assembly to the DH9104. Tested it and found that it would need 1/2 Left Trim to offset the larger Tail Blade's pulling to the Right.

I trimmed the Tail Blade to the First colored line on each end and now, little to no left trim is necessary.

This more closely resembles the original action of the DH9104 Tail system.

I also put the MJX F45 Tail Fin and Stabilizer on the DH9104, adding some color to the back end and since the MJX Tail Fin is larger, it allows the Tail Blade to clear the ground better.

So... now I am running a DH9104 with an MJX F45 Motor Set and Tail System.
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Old Oct 16, 2012, 01:47 PM
AMA 994002
matiac's Avatar
United States, RI, Westerly
Joined May 2012
1,050 Posts
I never did see what kind of metal replacement swash Killbucket had for his 9104, and whether or not he modded it for 4 ch. I've been wondering if the entire mainshaft could be replaced for an all metal one? Have had this one for 7 months of pretty much trouble free flight after a few minor mods to it (modeling clay in the nose, and control rod turned up), has anyone tried shortening the main blades? Don't know if it's correct or not, but I seem to remember reading somewhere that doing that improved forward flight too?
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Old Oct 21, 2012, 04:39 AM
Micro Heli mods
Tumppi T's Avatar
Finland, Tuusula
Joined Mar 2012
181 Posts
Quote:
Originally Posted by matiac View Post
I never did see what kind of metal replacement swash Killbucket had for his 9104, and whether or not he modded it for 4 ch. I've been wondering if the entire mainshaft could be replaced for an all metal one? Have had this one for 7 months of pretty much trouble free flight after a few minor mods to it (modeling clay in the nose, and control rod turned up), has anyone tried shortening the main blades? Don't know if it's correct or not, but I seem to remember reading somewhere that doing that improved forward flight too?

Hi guys,

Great so see that I'm not the onlyone who is still flying and modifying the DH9104

I have E-Flite Blade SR metal swashplate in my DH and it fits well to original mainshaft.



...and about shortening main blades....don't do it. I tryed....the main motor needs more throttle and when it's running faster, the tail must also run faster and it will burn quite soon.

Now i'm struggling with brushless tailmotor. I'm using MJX F45 TX & RX to get the 4th channel for aileon. It was pretty easy to mod the brushless main motor for that combination. The tail is not that easy but I love challenges.

Let's keep these DH:s flying

Safe flights and smooth landings,
- Tumppi
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Old Dec 05, 2012, 11:22 PM
Registered User
United States, OK, Oklahoma City
Joined Dec 2012
20 Posts
hey guys new to the forums here but couple of questions first off just got my dh 9104 a couple of days ago nice chopper but range sucks and flight with out the mods sucks now then i was wondering if i could use the rx board outa the 9117 on the 9104 and still keep it 3 channel? or is there any rx board that would work i do realize that i have to get the tx but thats fine and for question number 2 what other swash plate works best with this chopper?

thanks guys
lucky
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Old Dec 13, 2012, 02:39 AM
Micro Heli mods
Tumppi T's Avatar
Finland, Tuusula
Joined Mar 2012
181 Posts
Quote:
Originally Posted by lucky73129 View Post
hey guys new to the forums here but couple of questions first off just got my dh 9104 a couple of days ago nice chopper but range sucks and flight with out the mods sucks now then i was wondering if i could use the rx board outa the 9117 on the 9104 and still keep it 3 channel? or is there any rx board that would work i do realize that i have to get the tx but thats fine and for question number 2 what other swash plate works best with this chopper?

thanks guys
lucky
Hi lucky,

About the range ....be sure that the antenna wire doesn't touch any metal parts like tail boom. Leave it hanging free after the plastic tube of landing skid
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Old Dec 13, 2012, 05:28 PM
AMA 994002
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United States, RI, Westerly
Joined May 2012
1,050 Posts
Don't know if this has been posted here before, but here's mine, and I happen to think it flies pretty nice for what it is:
Double Horse 9104 Flight (4 min 59 sec)
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Old Dec 13, 2012, 06:48 PM
AMA 994002
matiac's Avatar
United States, RI, Westerly
Joined May 2012
1,050 Posts
Quote:
Originally Posted by lucky73129 View Post
hey guys new to the forums here but couple of questions first off just got my dh 9104 a couple of days ago nice chopper but range sucks and flight with out the mods sucks now then i was wondering if i could use the rx board outa the 9117 on the 9104 and still keep it 3 channel? or is there any rx board that would work i do realize that i have to get the tx but thats fine and for question number 2 what other swash plate works best with this chopper?

thanks guys
lucky
Why yes, yes you CAN use the 9116/7 RX brick, BUT...but, you'll have to replace the 9117 power switch with the 9104, requiring a little splicing-soldering, and if you're going to do the 4 channel thing you'll have to rotate the entire top assembly for the mainshaft 180 degrees, AND you'll have to use the 9116/7 swashplate, as the 9104's arms are too small, and actuating the servos will cause the swash to actually separate. You can keep pressing it back together, but you'd be better off getting the right swash for the job, but yeah, it can be done...as for range I've heard of people unraveling the antenna and extending it up the tail boom, but when I did that, there was even LESS range, so I re-wrapped it, and left it well enough alone. On the 27.145MHz setup, my average range was right in the neighborhood of a football field in radius...God any more than that it would be pretty hard to see. Thing I disliked about the 27 setup was the rather annoying tendancy for the chopper to "cut-out" in mid-flight...thank goodness I was high enough to where it never crashed, but that was the biggest reason I switched out to 2.4GHz ops...no more cut-out...oh yeah, you want to keep it 3 channel...just leave one servo port empty, then you don't have to rotate the top assembly for the mainshaft...
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Old Dec 27, 2012, 11:49 PM
Registered User
United States, OK, Oklahoma City
Joined Dec 2012
20 Posts
Quote:
Originally Posted by matiac View Post
Don't know if this has been posted here before, but here's mine, and I happen to think it flies pretty nice for what it is:
http://www.youtube.com/watch?v=MGMv7kdgFFk
so is that one a 4 channel or is it stock? and if its stock what mods did you do to it to make it fly right i want mine to fly right.....
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Old Jan 07, 2013, 05:43 PM
Registered User
New Zealand, Taranaki, New Plymouth
Joined Aug 2012
16 Posts
Hi All

New to the RC Helicopter game. I have a Double Horse 9104 and have an issue with it. Something is not right with either the main motor or the receiver. I'm hoping that some advise will help me work out what I need to do.

Helicopter flew well out of the box. Not great on forward motion/speed, but overall it flew nicely. It had a couple of 'firm' landings, but nothing that I would call a crash.

The problem - When you initiate throttle movement the tail rotor spins for 0.5 sec and the main motor gives a small kick. Disconected the main motor, tail rotor seems to work fine on main throttle movement and on rudder movement. Removed main motor and the blades/shaft etc all seem to move nice and freely.

There was no percieved loss of power before the problem. There are some lights that flash on the control board, not sure if this is relevant...If it is I'll post what the sequence etc is.

Any help greatly appriciated.

Cheers
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Old Jan 21, 2013, 10:23 AM
Registered User
Joined Dec 2012
94 Posts
hello i just purchased this 9104 from a guy i work with he took the pc off and order 1 for a 9117,swashplate and 2nd servo,and servo arms for a 9117 can i hook all this up on the 9104 and have a 4ch and if so how do i know where everything plugs in on pc board i also know i will need a transmitter to operate this anyone have some answers i couldn't beat the price 25.00 for everything he said he is done with these
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Old Jan 21, 2013, 10:36 AM
LearningFast
United States, LA, Denham Springs
Joined Jan 2012
410 Posts
Look for a 9117 TX for this. I am not sure if anything else will bind with it. I personally don't like the swashplate and how it is setup. I modded mine to a 5 channel withe 3 servos. Another went to 2 servos, but with a different swashplate setup. That was a good price! He gave you the other pieces to upgrade it up to a 9117? Good deal. Then a 9117 TX should be the answer.
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Old Jan 21, 2013, 12:26 PM
Registered User
Joined Dec 2012
94 Posts
yea i figured i cant go wrong with the price and this is a step up from my dh 9118 i will order the 9117 transmitter from ebay. ut how do i know where all the couplers go on the pc board i don't want to mess this up like to try and fly it in the spring
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Old Jan 21, 2013, 12:44 PM
LearningFast
United States, LA, Denham Springs
Joined Jan 2012
410 Posts
I am sure someone can take a picture of theirs and show you where all the hook ups are. You should just have one for each motor, you should see them. They should have different size plugs, but not sure. Did you get extra batteries for it. If not, I would suggest these: http://www.hobbypartz.com/32p-20c-1300-2s1p-74.html . They are almost twice the capacity of the originals 7.4v 20c batteries. You can change the plug to a jst for charging with you system, but I suggest a dedicated charger such as the Thunder ac680. It will charge in a very short time, say 20 minutes vice hours. Just a suggestion. Watch out, it is addictive! Fly it for a while before you spend alot of money!
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Old Jan 21, 2013, 01:06 PM
Registered User
Joined Dec 2012
94 Posts
thanks for the battery info there was no battery with it but i have a extra stock from my 9118 to start but the battery holder seam much small then on the 9118 i have considered a new battery charger i take it you like the thunder i will look that and the new battery up..
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