Airworld Gee Bee R3 with Moki 400
#26
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Here is a link with some pictures
https://plus.google.com/photos/109019909731702760145/albums/6097434502850332497
Pierre
https://plus.google.com/photos/109019909731702760145/albums/6097434502850332497
Pierre
#27

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Pierre,
Very nice. I have been following your pictures.
Some suggestions if I could please. This plane flies and lands best with a nose heavy C/G. It will most likely end up being tail heavy and require additional weight on the motor dome. It needs very little rudder movement to hold a knife edge attitude. I used an SWB servo tray in mine similar to yours. One Hitec 7950 servo was adequate for the rudder. I used 2.5 inch width of a straight bell crank arm. A 2 inch width arm for the rudder would have been plenty and would take advantage of full servo resolution. I would suggest a temporary placement of the SWB servo tray until you balance your airplane in order to save unnecessary added weight in the aft section. Would recommend a C/G of 140 mm aft of leading wing edge.
Regards - Jaketab
Very nice. I have been following your pictures.
Some suggestions if I could please. This plane flies and lands best with a nose heavy C/G. It will most likely end up being tail heavy and require additional weight on the motor dome. It needs very little rudder movement to hold a knife edge attitude. I used an SWB servo tray in mine similar to yours. One Hitec 7950 servo was adequate for the rudder. I used 2.5 inch width of a straight bell crank arm. A 2 inch width arm for the rudder would have been plenty and would take advantage of full servo resolution. I would suggest a temporary placement of the SWB servo tray until you balance your airplane in order to save unnecessary added weight in the aft section. Would recommend a C/G of 140 mm aft of leading wing edge.
Regards - Jaketab
#28
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Hi,
All recommendation are very welcome.
Thank you for that. I will pay attention to the CG, I know how important it is...
Can I ask you a question?
What have you done with the tail wheel?
We received a carbon tube, I have no idea how to fix it in the tail? ( I took the picture from



I do not really want to glue the tube.. just in case of ..
thank you,
Pierre
All recommendation are very welcome.
Thank you for that. I will pay attention to the CG, I know how important it is...
Can I ask you a question?
What have you done with the tail wheel?
We received a carbon tube, I have no idea how to fix it in the tail? ( I took the picture from
I do not really want to glue the tube.. just in case of ..
thank you,
Pierre
#29

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Location: Nærbø, NORWAY
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My kit came With difrent tailweel setup and i did not like the orginal system so i went for one from http://whiteroseeng.com/ and are wery happy With their Product!
Geir
#30

My Feedback: (2)

Pierre,
I like the way Salte modified his tailwheel. That is the way most prefer.
I used the carbon fiber rod like yours. I had an aluminum bracket made and attached it to the vertical fin post.
A tip someone shared with me - make the tailwheel tall as possible to lift the aft end higher.
When landing, that will decrease the angle of attack and possibly keep the airplane from leaping back into the air.
Regards - Jaketab
I like the way Salte modified his tailwheel. That is the way most prefer.
I used the carbon fiber rod like yours. I had an aluminum bracket made and attached it to the vertical fin post.
A tip someone shared with me - make the tailwheel tall as possible to lift the aft end higher.
When landing, that will decrease the angle of attack and possibly keep the airplane from leaping back into the air.
Regards - Jaketab
#31

My Feedback: (2)

Pierre,
Your build is progressing very fast. When will be the maiden flight ???
Can't weight to see it fly if you can have a video taken.
It may motivate me to begin repairs and try one more time on my Airworld Gee Bee RE
My downfall seemed to be a tail heavy plane that I could not land.
Best of luck. Jaketab
Your build is progressing very fast. When will be the maiden flight ???
Can't weight to see it fly if you can have a video taken.
It may motivate me to begin repairs and try one more time on my Airworld Gee Bee RE
My downfall seemed to be a tail heavy plane that I could not land.
Best of luck. Jaketab
#32
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Hi Jeketp,
we we are progressing well. Finishing the flight control.... Not easy ..the ailerons do not fit very well... Take some time.
The electronic installation is in progress. I'm a bit surprise by the CG, it seems to be quiet aft already..
i'll try to have the CG around 15cm from the leading edge.
i should start the engine next week and them ..... Well, wait for the Belgian weather to get a bit better.
i need to work on a stand for the transport ... I have no plan yet , what have you done?
I will of course let you know about the progress...
pierrre
we we are progressing well. Finishing the flight control.... Not easy ..the ailerons do not fit very well... Take some time.
The electronic installation is in progress. I'm a bit surprise by the CG, it seems to be quiet aft already..
i'll try to have the CG around 15cm from the leading edge.
i should start the engine next week and them ..... Well, wait for the Belgian weather to get a bit better.
i need to work on a stand for the transport ... I have no plan yet , what have you done?
I will of course let you know about the progress...
pierrre
#33

My Feedback: (2)

Pierre,
Hope you gain some ideas from attached photos. The bracket on the wing tube was used to balance. The builders of this model that I have spoken with add weight to the dome to balance. The downfall of my plane was not enough weight up front. A tail heavy model will make landing almost impossible. I would recommend a nose heavy C/G of approxiamately 140 mm to start. The transport stand folds down when the wings and gear are assembled so the plane can be let down without the aid of another.
Regards - Jaketab
#34

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You made a wery Nice transport stand Jaketab:-) I went for a more simple Version using the wingtube and tailweel bracket,i can plug on wings and then slide the gee bee back off the stand by my self.
My CG is in front of the wingtube With wery little adjustments after.I have flying the R3 With both moki 250 and 400 and With the 250 the plane is wery light and it is hard to take off speed for a good landing! The R3 handels a lot of weight and i think the 300 makes a good engine With the extra weight vs the 250! then again the 400 is on the Heavy side and you have to use Heavy duty springs and taiweel bracket and use more speed when landing! So my advice on building this airplane With 250 and 300 is not to have focus on building light! it handels better in air and landing coming out on the Heavy side.
Geir
#35

My Feedback: (2)

Geir and Pierre,
Correct - recommended C/G from Airworld is 150 mm. That puts the mark on the front edge of the wing tube.
If I were to rebuild, I would balance at 140 - 145 mm. I noticed from Pierre's pictures, that he is using dual rudder servos with a servo tray mount which add weight to the aft section. Paint itself will add weight to the aft section. When I built mine with the 250, I used only 1 high torque serve for the rudder mounted the batteries in the dome, and added approximately 1 lb. of ballast to the dome throat to balance.
Regards - Jaketab
Correct - recommended C/G from Airworld is 150 mm. That puts the mark on the front edge of the wing tube.
If I were to rebuild, I would balance at 140 - 145 mm. I noticed from Pierre's pictures, that he is using dual rudder servos with a servo tray mount which add weight to the aft section. Paint itself will add weight to the aft section. When I built mine with the 250, I used only 1 high torque serve for the rudder mounted the batteries in the dome, and added approximately 1 lb. of ballast to the dome throat to balance.
Regards - Jaketab
#36
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Hi Guys,
Happy like a young kid...
I ran the Moki for the first time last night in a friend's garage.. Just few seconds but engine seems to be great, easy to start..
http://youtu.be/S_RuBmmqcMs?list=UU7...Uvs9xL80fUWAgg
http://youtu.be/7fcZ7SJudZE
Thank you for the info above :-)
I will definitely take great care of the CG, mine seems to be a bit tail heavy even with the Moki 300.
I have few more questions:
The engine seems to have some pitch up, have you got the same?
Now, working on final radio installation and a stand.. want to be able to assemble it on my own at the field.
Pierre
Happy like a young kid...
I ran the Moki for the first time last night in a friend's garage.. Just few seconds but engine seems to be great, easy to start..
http://youtu.be/S_RuBmmqcMs?list=UU7...Uvs9xL80fUWAgg
http://youtu.be/7fcZ7SJudZE
Thank you for the info above :-)
I will definitely take great care of the CG, mine seems to be a bit tail heavy even with the Moki 300.
I have few more questions:
The engine seems to have some pitch up, have you got the same?
Now, working on final radio installation and a stand.. want to be able to assemble it on my own at the field.
Pierre
Last edited by Pierre747; 02-07-2015 at 04:25 AM.
#37
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Hi,
Me again... Here is my next question :-)
When I tide up the wire ( just enough), there is a gap between the trailing edge of the wing and the fuselage.
I have tried plenty of different setting but I always have a gap between the wing and the fuselage???
Did you get the same problem?
Thank you,
Pierre
Me again... Here is my next question :-)
When I tide up the wire ( just enough), there is a gap between the trailing edge of the wing and the fuselage.
I have tried plenty of different setting but I always have a gap between the wing and the fuselage???
Did you get the same problem?
Thank you,
Pierre
#38

My Feedback: (2)

Pierre,
The 300 sounds like it's running on all 5 cylinders right out of the box. Very nice.
The information I received from Air World, indicates the offset thrust alignment for the motor is 1 degree down thrust and 3 degree right thrust. The offset thrust was built into the dome in mine. Did you have to modify the dome to accommodate the longer 300 cc motor ??????
The flying wires should not be too tight, but I still had the same problem with a gap in the wing trailing edge. I modified the aft wing pin for a 3mm bolt to keep the trailing edge of the wing from pulling out and gapping.
Don't be surprised if you have to add as much as 1 kg to the dome to balance.
Regards - Jaketab
The 300 sounds like it's running on all 5 cylinders right out of the box. Very nice.
The information I received from Air World, indicates the offset thrust alignment for the motor is 1 degree down thrust and 3 degree right thrust. The offset thrust was built into the dome in mine. Did you have to modify the dome to accommodate the longer 300 cc motor ??????
The flying wires should not be too tight, but I still had the same problem with a gap in the wing trailing edge. I modified the aft wing pin for a 3mm bolt to keep the trailing edge of the wing from pulling out and gapping.
Don't be surprised if you have to add as much as 1 kg to the dome to balance.
Regards - Jaketab
#39

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Hi Guys,
Happy like a young kid...
I ran the Moki for the first time last night in a friend's garage.. Just few seconds but engine seems to be great, easy to start..
http://youtu.be/S_RuBmmqcMs?list=UU7...Uvs9xL80fUWAgg
http://youtu.be/7fcZ7SJudZE
Thank you for the info above :-)
I will definitely take great care of the CG, mine seems to be a bit tail heavy even with the Moki 300.
I have few more questions:
The engine seems to have some pitch up, have you got the same?
Now, working on final radio installation and a stand.. want to be able to assemble it on my own at the field.
Pierre
Happy like a young kid...
I ran the Moki for the first time last night in a friend's garage.. Just few seconds but engine seems to be great, easy to start..
http://youtu.be/S_RuBmmqcMs?list=UU7...Uvs9xL80fUWAgg
http://youtu.be/7fcZ7SJudZE
Thank you for the info above :-)
I will definitely take great care of the CG, mine seems to be a bit tail heavy even with the Moki 300.
I have few more questions:
The engine seems to have some pitch up, have you got the same?
Now, working on final radio installation and a stand.. want to be able to assemble it on my own at the field.
Pierre
Geir
#40
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maiden flight was done today... All went well
https://youtu.be/1Y5aCEq9_aw
Video is a bit long but I did not want to cut more frame of me GeeBee....
https://youtu.be/1Y5aCEq9_aw
Video is a bit long but I did not want to cut more frame of me GeeBee....

#42
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https://youtu.be/1Y5aCEq9_aw
Hi Jaketab,
For the first flight, I had the 3 batteries under the canopy with a CG 15cm behind leading edge ( recommended ).
The airplane was perfectly neutral..... a bit too much. So for the 2sd flight, I moved 2 batteries forward.
It was much better. Now, when inverted, the plane start a shallow descent. I'll keep it like that for a while.... time to get use to the plane.
The Airplane ( before painting) is around 25,7kg... Found it a bit heavy but it seems to fly great.
Painting .... Well not 100% sure yet but I think I'll go for the texaco
I'll post some pictures when the painting is done..
Regards,
Pierre
For the first flight, I had the 3 batteries under the canopy with a CG 15cm behind leading edge ( recommended ).
The airplane was perfectly neutral..... a bit too much. So for the 2sd flight, I moved 2 batteries forward.
It was much better. Now, when inverted, the plane start a shallow descent. I'll keep it like that for a while.... time to get use to the plane.
The Airplane ( before painting) is around 25,7kg... Found it a bit heavy but it seems to fly great.
Painting .... Well not 100% sure yet but I think I'll go for the texaco
I'll post some pictures when the painting is done..
Regards,
Pierre
#48
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i ordered a Gee Bee R3 from Airworld last month and am looking to order a motor. from all i have read the aircraft seems to be tail heavy. my initial plan was to put a Moki 300 on the airplane to fix the cg issue. is there any downside to going with the 400 instead, my understanding is the motor is an additional 6 lbs heavier than the 300. any feedback is appreciated
Gregg
Gregg
#49

My Feedback: (2)

i ordered a Gee Bee R3 from Airworld last month and am looking to order a motor. from all i have read the aircraft seems to be tail heavy. my initial plan was to put a Moki 300 on the airplane to fix the cg issue. is there any downside to going with the 400 instead, my understanding is the motor is an additional 6 lbs heavier than the 300. any feedback is appreciated
Gregg
Gregg
It's been about 9 years since I lost my R3. Glad to help if I can. If I were to do all over again, I would not recommend the Moki 400. I have seen several videos of the R3 with a 400. It may add too much weight and cause a landing problem. IMO the 300 would be a good match for the R3. When you build, keep all the components toward the front. The 300 will fly the R3 with much authority. Whenever you have a question just post in the forum. I have pictures to post that may help with questions. Enjoy the build. Sometimes it's a head scratcher that requires backyard engineering.
BTW - I responded to your PM with my phone #.
Regards - J Tab