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Old Aug 31, 2008, 11:10 PM
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Hokusei Model GeeBee EPP BX

This is my second Hokusei Model EPP plane...











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Old Aug 31, 2008, 11:14 PM
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Hong Kong
Joined Nov 2006
70 Posts
Dualsky XM2826CA-15 1200KV
APC 10x4.7SF
EMAX ESC 18A
Futaba 3110 x 3 (Ailerons & Elevator)
Waypoint 060BB x 1 (Rudder)
Futaba 146iP
Dualsky XP08503GT 11.1V 850mAh 25-30C
AUW : 406g

Rudder...


Elevator and Stablizer...


Main Wing and Aileron...


Fuselage...


Gear...
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Old Aug 31, 2008, 11:19 PM
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Photos taken in flying site...







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Old Aug 31, 2008, 11:28 PM
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Video...

GeeBee EPP BX (30-08-2008) (3 min 5 sec)
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Old Sep 02, 2008, 03:47 AM
How many planes is too many?
groovejet's Avatar
Melbourne, Australia
Joined Aug 2007
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Hi Jeff,

The photos look fantastic. What do you think of the Gee Bee now that you've flown it?
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Old Sep 02, 2008, 11:18 PM
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Hong Kong
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Quote:
Originally Posted by groovejet
Hi Jeff,

The photos look fantastic. What do you think of the Gee Bee now that you've flown it?
Hi GJ,

Thanks!

GeeBee EPP BX is not as stable as Primus EPP Z for hovering, may be it is due to the shorter fuselage length...

And the speed for KE is higher...

However, it is easier to perform harrier, wall and waterfall...

The nose heavy issue happens in GeeBee again...

Cheers,
Jeff
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Old Sep 03, 2008, 04:09 AM
How many planes is too many?
groovejet's Avatar
Melbourne, Australia
Joined Aug 2007
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Quote:
Originally Posted by AlfaR
The nose heavy issue happens in GeeBee again...
Jeff,

Is it nose heavy even with the battery arranged vertically right up against the foam edge of the landing gear?

You could save some nose weight if you switch to a GWS prop. The saving is likely to be 5-10g and as the prop is on the tip on the nose, you will get more benefit from the nose lightening than if you used a motor that was lighter by the same amount. You can't really use a lighter motor anyway; that Dualsky is a strong motor for its weight and anything lighter will likely have less power.

A GWS 9x5 (EP9050) prop is almost identical in thrust, amps and pitch speed to an APC 9x4.7 SF on just about any motor. A GWS 10x6 will draw about 2 more amps on your Dualsky motor and will really push it to the limit. The APC 10x4.7 SF you are using will likely push your Dualsky motor beyond its specs at full throttle, but I'm basing this on you being at a similar altitude to me in Melbourne. Have you used this motor and prop combo before (like on your Primus) ?

If you haven't measured the current statically or during flight, I'd recommend you be careful with the throttle and keep an eye on the motor temperature.
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Old Sep 03, 2008, 08:35 AM
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Hong Kong
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Quote:
Originally Posted by groovejet
Jeff,

Is it nose heavy even with the battery arranged vertically right up against the foam edge of the landing gear?

You could save some nose weight if you switch to a GWS prop. The saving is likely to be 5-10g and as the prop is on the tip on the nose, you will get more benefit from the nose lightening than if you used a motor that was lighter by the same amount. You can't really use a lighter motor anyway; that Dualsky is a strong motor for its weight and anything lighter will likely have less power.

A GWS 9x5 (EP9050) prop is almost identical in thrust, amps and pitch speed to an APC 9x4.7 SF on just about any motor. A GWS 10x6 will draw about 2 more amps on your Dualsky motor and will really push it to the limit. The APC 10x4.7 SF you are using will likely push your Dualsky motor beyond its specs at full throttle, but I'm basing this on you being at a similar altitude to me in Melbourne. Have you used this motor and prop combo before (like on your Primus) ?

If you haven't measured the current statically or during flight, I'd recommend you be careful with the throttle and keep an eye on the motor temperature.
GJ,

Thank you for your suggestions...

The battery is already at the rear most position as shown in the photo below...


It is a good idea to use GWS prop instead of APC, and I should have stock at home...

For the motor and 10x4.7SF combo, I tried it in Primus before...
According to the recommended configuration in Hokusei's website, it uses 10x4.7SF with this little motor...
http://www.hokusei-japan.com/product...us-epp-v2.html

Your guess is right, the motor is quite hot after 6 minutes flight under 3X degree Celsius... 10x4.7SF should be the upper margin of this little motor...
BTW, my location is at sea level...

I have measured the motor combo in Primus, I cant remember exactly what the loading current is, I think it should be around 14-16A...

If I have time, I shall measure the thrust and loading current later again...
Here is the setup I used to measure the data...


Cheers,
Jeff
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Old Sep 14, 2008, 11:03 PM
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One more video taken on yesterday...

GeeBee EPP BX (14-09-2008) (5 min 0 sec)
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Old Sep 15, 2008, 03:22 AM
How many planes is too many?
groovejet's Avatar
Melbourne, Australia
Joined Aug 2007
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Hi Jeff,

Thanks for posting that video. The Gee Bee looks like a very stable plane to fly. How do you think it compares to the Primus?

I'm getting very interested in the Gee Bee, especially if I can keep it light like you Gee Bee. I'm not familiar with the servos you used. What do they weigh? Also, have you solved your nose heavy problem? The nose heavy issue makes me nervous, especially as you are using a light battery mounted vertically and still have issues.
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Old Sep 15, 2008, 11:26 AM
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Hong Kong
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Quote:
Originally Posted by groovejet
Hi Jeff,

Thanks for posting that video. The Gee Bee looks like a very stable plane to fly. How do you think it compares to the Primus?

I'm getting very interested in the Gee Bee, especially if I can keep it light like you Gee Bee. I'm not familiar with the servos you used. What do they weigh? Also, have you solved your nose heavy problem? The nose heavy issue makes me nervous, especially as you are using a light battery mounted vertically and still have issues.
Hi GJ,

Up to now, I feel that GeeBee is designed for stall type maneuver while Primus is suitable for pattern flying...
If you like to do hovering, torque roll, harrier, etc, GeeBee is good for you...

The Futaba S3110 is around 7.7g, I use this servo in some of my planes, it works so far so good...

I add 10g at the tail in order to move the CG to 1.5cm behind the recommended position and I feel comfortable at this CG position...

Cheers,
Jeff
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Old Sep 18, 2008, 02:22 AM
How many planes is too many?
groovejet's Avatar
Melbourne, Australia
Joined Aug 2007
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Quote:
Originally Posted by AlfaR
Hi GJ,

Up to now, I feel that GeeBee is designed for stall type maneuver while Primus is suitable for pattern flying...
If you like to do hovering, torque roll, harrier, etc, GeeBee is good for you...

The Futaba S3110 is around 7.7g, I use this servo in some of my planes, it works so far so good...

I add 10g at the tail in order to move the CG to 1.5cm behind the recommended position and I feel comfortable at this CG position...

Cheers,
Jeff
Thanks for that info Jeff. It's pity that you needed to add weight to the tail, but 10g to make it fly better is a reasonable tradeoff.

BTW would it be possible to put the battery up top if you cut a hole for it? Typically the landing gear prevents a battery from moving back to the right position, but often the top half of a plane doesn't have such restrictions. I'm wondering if I might do that if I decide to buy myself a Gee Bee.
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Old Sep 18, 2008, 03:56 AM
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Quote:
Originally Posted by groovejet
Thanks for that info Jeff. It's pity that you needed to add weight to the tail, but 10g to make it fly better is a reasonable tradeoff.

BTW would it be possible to put the battery up top if you cut a hole for it? Typically the landing gear prevents a battery from moving back to the right position, but often the top half of a plane doesn't have such restrictions. I'm wondering if I might do that if I decide to buy myself a Gee Bee.
It is possible to put the battery up top...


But I am not sure whether the top part is wide enough to accommodate your batteries...
Also, you need to find a way to open and close the top part of the fuselage for battery changing...
Currently, the top part is sealed permanently by glue in my GeeBee...

Cheers,
Jeff
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Old Sep 24, 2008, 10:49 AM
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Hamilton, Canada
Joined Nov 2005
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Gee Bee was my first Hokusei plane. It stalled very well. I think I was lucky to have it when I was learning to harrier and hover because it was so stable doing high alpha maneuvers. (I was faithfully observing Hokusei's CG recommendation.) If I remember correctly, my Gee Bee was just under 400 grams and had the feel of a low wing-loading plane. It was really a floater but could not deal with strong wind very well.

Thank you, Jeff, for sharing your photos and videos with us. Did you have your video camera on a tripod for the first video clip?

Max
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Old Sep 24, 2008, 07:53 PM
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Hong Kong
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Quote:
Originally Posted by feda
Gee Bee was my first Hokusei plane. It stalled very well. I think I was lucky to have it when I was learning to harrier and hover because it was so stable doing high alpha maneuvers. (I was faithfully observing Hokusei's CG recommendation.) If I remember correctly, my Gee Bee was just under 400 grams and had the feel of a low wing-loading plane. It was really a floater but could not deal with strong wind very well.

Thank you, Jeff, for sharing your photos and videos with us. Did you have your video camera on a tripod for the first video clip?

Max
Hi Max,

My GeeBee is 408g...

I use this plane to practice harrier too...

You are right, I mounted the video cam on a tripod as I was flying alone that day...

Cheers,
Jeff
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