Y/A F-18 Twin With Two DS-94?  
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All Forums >> Electric Aircraft Universe >> Electric RC Jets >> Y/A F-18 Twin With Two DS-94? Page: [1]

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Y/A F-18 Twin With Two DS-94? - 5/13/2006 12:24:42 PM   
X-spec


 

Posts: 96
Joined: 5/28/2004
From: SINGAPORE, SINGAPORE
Status: offline

HI! To all jet flyers,

I am looking at the Y/A F-18 Twin fuselage,as most of them will install twin or single turbine on her and also twin nitro 91 size ducted fan too, but is there anybody try it with Electric before? I was thinking with this big bug surely needed twin big fan for it and came to my mind was the DS-94 DIA 3HP fan a single fan unit give thrust of 19lbs which about almost the same thrust to a Jetcat P80, So my question will be if install two unit just like two P80 will she fly?


X-Spec(James)
       Post #: 1

RE: Y/A F-18 Twin With Two DS-94? - 5/13/2006 7:12:59 PM   
Larry Dudeck



Posts: 281
Joined: 11/20/2002
From: Williamsville, NY, USA
Status: offline 		I would say the bug will fly just fine with the twin EDF's. Using LiPo's batteries, the total AUW will not be much different than turbines and a full fuel load.

One thing to consider.

The EDF static thrust of 19 lbs, or 38 lbs for the twin set up, is the maximum available. With EDF's the thrust decreases as the plane's air speed increases while a turbine's thrust is more constant. So, all things being equal in the same air frame, the turbine powered version will have a higher max. speed compared to the EDF powered bug.

If maximum speed is what you are aiming for, then the turbine is the path to take.

(in reply to X-spec)
       Post #: 2

RE: Y/A F-18 Twin With Two DS-94? - 5/14/2006 9:56:41 AM   
X-spec


 

Posts: 96
Joined: 5/28/2004
From: SINGAPORE, SINGAPORE
Status: offline

Through the info giving by Schuebeler website the DS-94 thrust max is 19lbs but to what I know is electric after afew sec the amp will drop so it might means the thrust might be droping below 19lbs thrust too. In this case will the thrust able to keep the bug on air? I know the twin bug weight quite heavy but if two DS-94 is in used can it still be able to handle it?


X-Spec(James)

(in reply to Larry Dudeck)
       Post #: 3

RE: Y/A F-18 Twin With Two DS-94? - 5/18/2006 2:48:46 AM   
Larry Dudeck



Posts: 281
Joined: 11/20/2002
From: Williamsville, NY, USA
Status: offline 		The drop off in thrust due to decreasing amps is a function of the battery pack.

I have no idea of what your plane's weight is but a good rule of thumb is to have a thrust/weight ratio greater than .33

So if the 19 lbs of static thrust is reduced by half (due to reducing current and the fact the thrust diminshes as the planes velocity increases) the fan is producing 9.5 lbs of thrust. If your plane weighs 15 lbs, this is a T/W of 9.5/15 or .6 The plane won't perform verticals but will still fly very well.

My EDF's typically have a T/W of .35~.42 as measured on the bench. So, when flying the thrust is reduced to some lesser value and the plane continues to fly just fine.

In reality, the T/W only has to be on the order of 0.2 to keep the plane airborne but she won't be able to take off at this low T/W ratio.

(in reply to X-spec)
       Post #: 4

RE: Y/A F-18 Twin With Two DS-94? - 5/22/2006 7:23:06 AM   
changeup


 

Posts: 34
Joined: 1/21/2003
From: San Diego, CA, USA
Status: offline 		what motors are you using with those expensive DS-94's?

(in reply to Larry Dudeck)
       Post #: 5

RE: Y/A F-18 Twin With Two DS-94? - 5/22/2006 9:57:32 PM   
CTulanko



Posts: 340
Joined: 2/17/2004
From: Cincinnati, OH, USA
Status: offline 		Some guys are using the Neu motors...real workhorses.

The biggest problems with Dual DS-94's are cost and power management. The cost for a single setup nears that of a turbine, after factoring in the fan, motor, esc and major rack of Lipos. As far as power management goes, A turbine can easily be refueled for the next flight, while a twin DS-94 would probably require its own power generator to recycle all those batteries for more than one flight a day.

Carl

< Message edited by CTulanko -- 5/22/2006 9:58:02 PM >

(in reply to changeup)
       Post #: 6

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