Vmar Easy 3D Conversion
02-17-2005, 03:07 PM
#26
Member
Join Date: Nov 2004
Location: marshall,
VA
Posts: 85
Likes: 0
Received 0 Likes
on
0 Posts
RE: Vmar Easy 3D Conversion
Greg, how soon will the kokam 4cell 3200 packs be available?
I have a world models ultimate 30 biplane I converted using a 4120/14, I use several types of packs in it, but I am looking forward to these batteries.
Kevin
I have a world models ultimate 30 biplane I converted using a 4120/14, I use several types of packs in it, but I am looking forward to these batteries.
Kevin
02-17-2005, 04:12 PM
#27
Senior Member
Thread Starter
RE: Vmar Easy 3D Conversion
Hi Kevin,
That's a great question!
I've requested an answer right from the source so stay tuned...
Below is my new 4-cell Kokam 3.2AH (20C) pack that weighs 12.8oz. It is shown with a 3.0AH NiMH pack for size comparison. Note that the new cell width is the same as a sub-C cell length. The 4-cell Lithium pack has a voltage equal to about 14 cells of 3300mAh NiMH which weighs about 26oz or twice the weight of the Kokam pack. This is a pre-production test pack without the taps to monitor each cell.
A 3-cell Kokam 3.2AH pack would have a similar size and weight to a 6-cell sub-C pack but with the voltage of a 10-cell NiMH pack.
That's a great question!
I've requested an answer right from the source so stay tuned...
Below is my new 4-cell Kokam 3.2AH (20C) pack that weighs 12.8oz. It is shown with a 3.0AH NiMH pack for size comparison. Note that the new cell width is the same as a sub-C cell length. The 4-cell Lithium pack has a voltage equal to about 14 cells of 3300mAh NiMH which weighs about 26oz or twice the weight of the Kokam pack. This is a pre-production test pack without the taps to monitor each cell.
A 3-cell Kokam 3.2AH pack would have a similar size and weight to a 6-cell sub-C pack but with the voltage of a 10-cell NiMH pack.
02-23-2005, 01:08 PM
#28
Senior Member
Thread Starter
RE: Vmar Easy 3D Conversion
I dropped 1.5oz in my tail by switching to the [link=http://www.hobby-lobby.com/servos.htm]HS-85MG[/link] servo. It has the strength of a standard servo but only half the weight.
My Easy 3D was RTF at 74oz (4.6lbs) using the 13oz, 4-cell, Kokam 3.2AH (20C) pack. The CG was still a bit aft but reasonable to test fly.
My Easy 3D was RTF at 74oz (4.6lbs) using the 13oz, 4-cell, Kokam 3.2AH (20C) pack. The CG was still a bit aft but reasonable to test fly.
04-20-2005, 04:40 PM
#29
Senior Member
Thread Starter
RE: Vmar Easy 3D Conversion
Now that the flying fields are open again, I finally got a chance to fly the Easy 3D.
Although it flew ok and had awesome power, it is too pitch sensitive so being 1/2" to 3/4" back from the recommended CG setting is still to far.
Although it flew ok and had awesome power, it is too pitch sensitive so being 1/2" to 3/4" back from the recommended CG setting is still to far.
04-20-2005, 04:45 PM
#30
Senior Member
Thread Starter
RE: Vmar Easy 3D Conversion
The plane seemed almost impossible to stall and recovered quickly and gracefully when it did. When landing in a good headwind, we needed to completely shut off the motor power to get it to come down or it would sit in a harrier-like hover position. These are probably characteristics of the thick "D" shaped airfoil on the wing leading edge.
Since I am out of options to move the 4-cell Kokam 3.2AH pack any more forward, I am thinking of trying an aluminum spinner to add some extra nose weight.
Since I am out of options to move the 4-cell Kokam 3.2AH pack any more forward, I am thinking of trying an aluminum spinner to add some extra nose weight.
06-16-2005, 02:47 PM
#32
Junior Member
Join Date: May 2004
Location: london, UNITED KINGDOM
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
RE: Vmar Easy 3D Conversion
Hi there Greg, one question;
do you fly ic version planes with the ic engine first before you go electric to compare performance, or not?
Thanks
do you fly ic version planes with the ic engine first before you go electric to compare performance, or not?
Thanks
06-16-2005, 06:36 PM
#33
Senior Member
Thread Starter
RE: Vmar Easy 3D Conversion
No, there is no reason to do so and plenty of reasons not to. For example, the vibration from the glow engine and slime from the fuel residue would not make for the best starting structure. Further, when the RTF weights and CG are similar, the plane will perform similar with either power system.
If the plane does not make for a good e-conversion, it does not mean that it is a bad plane. In the future, we will likely see many designs that are meant for either type of power system which will make assembly even easier for the electric enthusiast.
If the plane does not make for a good e-conversion, it does not mean that it is a bad plane. In the future, we will likely see many designs that are meant for either type of power system which will make assembly even easier for the electric enthusiast.
