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Components Selection

TreeCrash

Junior Member
#1
Hello, I am restoring a DH88 Comet (the Advanced Scale Models one http://media.globalhobby.com/manual/190101.PDF). The airframe seems to be solid and it has special air powered retracts, but is missing almost all the other components. This is my first time selecting and ordering components, so bear with me. I am planning on making this electric and fly it with a DX6i.

Currently it has one servo (for the flaps) Spektrum DS821 digital servo. Plus one motor (and a huge prop) Turnigy Aerodrive SK3548 1100kv.

I would like to order everything from hobbyking since I have ordered there before and they have good prices. Unfortunately there doesn't seem to be a Turnigy Aerodrive 1100kv anymore.

So, my first question is: Can I match a different type of motor with the same kv rating to the one that I have? Or should I buy two new motors exactly the same?

Then I need servos. The user manual has suggestions on what type to use where, but there is a lot of variety in servos.

Here are the suggested sizes and the ones I picked out.
• 2 x Metal geared micro servos for aileron control http://www.hobbyking.com/hobbyking/store/__27569__Turnigy_TGY_50090M_Metal_Gear_9g_Analog_Servo.html
• 3 x Standard size high torque servos for rudder, elevator and flap control http://www.hobbyking.com/hobbyking/...proof_Analog_Servo_40g_4_5kg_cm_0_13s_60.html
• 1 x Additional micro servo required if optional retractable landing gear is fitted

Most of the standard size ones are expensive, and I couldn't find one that I really liked for a lower price. What do you guys suggest? Brand, price range, etc. Do I actually need standard size?

Then I need batteries, speed controllers and props to match the motors that I get. Plus a 6 channel receiver for a DX6i and who knows what else. Mainly right now I need help selecting servos because I don't know anything about them.

Any other suggestions on what to do with this thing would also be appreciated :) Thanks.
 

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FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#3
Don't let Josh Bixler see that, he might try taking it from you. This is the plane they loosely based the FT Cruiser on.
 

quorneng

Active member
#6
TreeCrash
The full size Comet was/is certainly not considered a easy plane to fly and by all accounts a model is no easier with a very pronounced wing drop at the stall due to the narrow wing tips.

I trust you have the necessary skill & experience to fly such a beautiful plane.
 

TreeCrash

Junior Member
#7
I am 95% sure the Turnigy SK3548 is a rebranded EMP.
Hmm, I might look into that. Probably I will end up getting two new ones...

TreeCrash
The full size Comet was/is certainly not considered a easy plane to fly and by all accounts a model is no easier with a very pronounced wing drop at the stall due to the narrow wing tips.

I trust you have the necessary skill & experience to fly such a beautiful plane.
Not really, but hopefully I can acquire some skills before it is ready to fly. Who knows, I might be too scared to fly it and get someone else with more experience to do the maiden. It does sound challenging and it would be a shame to crash it. Of course I don't really want to see it sit around and acquire dust for the rest of it's life either....
 

TreeCrash

Junior Member
#8
Okay, I came up with a new, more detailed list of things to get. I am still missing some things, such as batteries and servo extensions (need to measure how long I need). I'm not entirely sure how to set up the power system for this bird (I have never setup anything, let alone a twin). The manual puts batteries in the wings with the motors and I presume it would need a third battery to power the receiver inside.... unless I ran an extension from one of the wings. I already have some nice Turnigy 2200mAh batteries, and it would be ideal if I could use those instead of buying different ones.

Anyhow, here is what I picked out. I got some suggestions for servos from another forum and have decided to get matching motors.

Standard servos (rudder and elevator)
http://www.hobbyking.com/hobbyking/...proof_Analog_Servo_40g_4_5kg_cm_0_13s_60.html

I measured the spot that the aileron servos fit in and realized that I am restricted by space. I think I can fit a mini servo in there though. I picked out one that was in stock, it seemed to have good ratings. Then I found the slim wing servos and realized this plane is actually setup for slim wing servos... unfortunately they are more expensive. So now I have to decide if I want to spend a bit more for servos that would just drop in, or buy the cheaper ones that would require a bit more work to install.

Aileron servos
http://www.hobbyking.com/hobbyking/...9MG_Metal_Gear_Servo_2_5kg_12_5g_0_14sec.html
http://www.hobbyking.com/hobbyking/...Slim_Wing_Analog_Servo_4_6kg_22g_0_14sec.html

Micro servo (pneumatic valve)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=662

Servo extensions - to be determined

Motors, there is a lot of variety in motors. I think this one fits within what the manual suggests. The one that came with the plane seems to be a bigger motor, probably comparable to this one: http://www.hobbyking.com/hobbyking/store/__16232__NTM_Prop_Drive_Series_35_48A_1100kv_640w.html, which has a max current of 70A, which I think is huge. The one I picked has a max of 32A and I figured I could match a 40A speed controller to it.

Motors
http://www.hobbyking.com/hobbyking/store/__16230__NTM_Prop_Drive_Series_35_30_1100kv_380w.html

Speed controllers
http://www.hobbyking.com/hobbyking/store/__2165__TURNIGY_Plush_40amp_Speed_Controller.html

Props are also confusing. I wanted 10x5 or 10x6, but don't know what type. Also, I figured counter rotating would fix the torquing problem on the twin, so I picked out some props that are both standard and counter rotating.

Props
http://www.hobbyking.com/hobbyking/..._and_Counter_Rotating_6pc_.html?strSearch=HCB

Receiver
http://www.hobbyking.com/hobbyking/...m_JR_DSM2_Compatible_6Ch_2_4Ghz_Receiver.html

Anything else I should be considering?