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Old Feb 10, 2009, 07:28 PM
jrb
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Edina, MN, USA
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Build & Fly -- Groovy 90 3A

This won't be a ready this weekend build; though it won't take too long to get it airworthy: http://www.airborne-models.com/html/...p?ProductID=77 .

It will be a longer wait for good weather for the maiden; so the build will be paced based on the forecast.

Got from LHS today, everything looks really good; here's the weights:
fuse 25
wings 22
eleva 6
rudder 2
Tot oz 55
3# 7oz

That's lighter than I would have expected -- off to a good start.

Rest of the harware is typical, so RTF won't be bad.

3 things I plan to do:
Add some wood in the landing block area; will use nylon rather than steel bolts
Glue fiber glass cowl parts together
Likely cover the tuned pipe tunnel.

More about the power set-up later.
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Old Feb 10, 2009, 09:58 PM
jrb
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Edina, MN, USA
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A bit more onfo:

Radio:
TX - JR 9303
RX - JR R700
Servos - JR DS-821 (4)
UBEC (HV)

ESC - Jeti Adv 77 Opto ( http://www.hobby-lobby.com/jetiblue.htm )
Motor - Scorpion 4025-16 ( http://www.innov8tivedesigns.com/pro...roducts_id=215 )

Battery A123-xS1P @ 40amps WOT:
Most likely 10S via Dewalt 36v, with leads solder to tabs -- w/15x8 & 9#.

But, may also look at 8S (2*4) -- w/16x10 & 8.5#.


Will also use my "standard" arming/charging arrangement as shown here:

Charging is via a MasTech 5020, 7minutes at 20amps; will have about 7 minutes of flight time too.
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Old Feb 10, 2009, 10:38 PM
jrb
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More thoughts:

Will likely servos per manual; maybe just a bit aft if easy.

Also, the configuration of Elevator allow this plane to be transported in a show/rifle type case -- maybe I can fly down to BNA next fall with it checked to bring it to the AirFoiler's E Fly-In!
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Old Feb 11, 2009, 08:15 AM
jrb
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Here's the Stab/Elav arrangement that should allow them to be easily removed for transport:
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Old Feb 11, 2009, 08:59 AM
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Oakland township, Michigan
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Jrb,

I have the 50 sized Groovy and it is a good flier; however, it ended up being a little heavy for its size. It came in at 6 lbs for a plane with a wing area of 530 sq in. I did not make any changes to it, except for those needed to mount the electric motor and battery. The attachment of the landing gear is weak and although I have not had any problems, all the landings have to be done gingerly. I would consider replacing it with a one piece unit if at all possible. These two piece landing gears place very high loads on the bolts, if the two halves became one, the loads on the bolts would go down considerably, making the landing gear much sturdier.

Good luck,

Teo
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Old Feb 11, 2009, 09:27 AM
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Rutherfordton, North Carolina, United States
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Jim,
It looks like you have a fine looking new project. I'll be watching this thread with great interest. This would be a great bird to bring to Tullahoma .
Ed
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Old Feb 11, 2009, 10:56 AM
jrb
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Thanks Ed!

Must be cost Yeo? Though its one piece on their .60 Velox; since I have one of those, I'll see if its gear could used -- just doesn't have the funny slant toward the back (don't really like it anyway).
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Old Feb 11, 2009, 11:44 AM
jrb
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Not cost?

Either set is $50 as a part .
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Old Feb 11, 2009, 04:44 PM
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Oakland township, Michigan
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Jrb,

It seems that either way, they still get you. I think the reason why the two piece assemblies have become popular has to do with packaging; they are probably easier to fit in the box. I believe that the gear is slanted towards the rear in order to get the main wheels closer to the CG; that allows the plane to rotate more easily during takeoff and landing. My biggest gripe with this arrangement is that it actually results in higher loads at the bolts that if the landing gear were one piece. I do not have a scanner, but if I were to sketch the forces it would be easy to visualize what it is that I mean (by the way, I am an enginerd).

Teo
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Old Feb 12, 2009, 07:53 AM
jrb
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Agree Teo!

Plenty of room for either 8 or 10 A123s; just like on the Velox the fusealge is wide open with the long hatch/cockpit and split wing w/tube.

The forward servo is the stock position for the rudder; looks like I could put it aft of the Elevator servo -- could even do it after build if needed.

The elevator is done via two music wires in tubes; don't plan to go to two servo in the tail unless really needed @ 1st CG check.

Here's a shot of the pipe tunnel. the forward end under the bottom cowl section will proved great motor cooling. Towards the aft end is a hardpoint that could easily be opened to give an exit point for battry/esc cooling. So I doubt I will "cover" the trough.
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Old Feb 12, 2009, 08:02 PM
jrb
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Full shot of hatch -- from firewall back.

Will even hold big packs: two TP8000-3S4Ps
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Old Feb 12, 2009, 08:30 PM
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Oklahoma City
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Jim, Thanks for the under the hatch pics. Looks like you made a good choice for E conversion pattern plane. Looking forward to the build.

Morris
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Old Feb 13, 2009, 05:17 AM
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Guntalingen, Switzerland
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Quote:
Originally Posted by viva_peru
Jrb,

I have the 50 sized Groovy and it is a good flier; however, it ended up being a little heavy for its size. It came in at 6 lbs for a plane with a wing area of 530 sq in. I did not make any changes to it, except for those needed to mount the electric motor and battery. The attachment of the landing gear is weak and although I have not had any problems, all the landings have to be done gingerly. I would consider replacing it with a one piece unit if at all possible. These two piece landing gears place very high loads on the bolts, if the two halves became one, the loads on the bolts would go down considerably, making the landing gear much sturdier.

Good luck,

Teo
So does my girlfriend. Hers is spot on the advertised weight for the glow version, i.e. 2350g or 5.2lbs. On 4s LiPo it's a great, easy, stable flyer. The gear did cause us some concern too, we reinforced the mounts and replaced it with an old wire gear that was lying around. We also did not mount the spats.
Lorenz
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Old Feb 13, 2009, 09:27 AM
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Oakland township, Michigan
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Lorenz,

I am just a little curious as to how your girlfriendīs Groovy ended up so light. I am using an AXI 4120/18 and a 5S pack for power. In order to get the plane to balance correctly I am also using a receiver pack. What is she using for power? I would also mention that your extremely lucky to have a girlfriend who shares the same interest.

Teo
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Old Feb 13, 2009, 09:29 AM
jrb
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RX pack aft of CG Teo?
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