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BJ Craft G2 Essence

Old 05-12-2016, 06:37 AM
  #176  
vatechguy3
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Originally Posted by vatechguy3
Thanks for the writeup.

Will go through this when i get home and see if i can follow.
And yes, i have the removable chin cowl.

Tony
Got my landing gear in.
Used a slightly different method. Will explain later when not on a phone.

Also, what material are you guys using between the wing and fuse to avoid rubbing?

Just about done with mine. Need to install wheel pants, wheels, tailwheel, then balance and glue in battery tray where it is needed.
The finalize radio setup.

Would love to maiden this weekend. Have a contest next weekend at the FARM club.

Tony
Old 05-12-2016, 08:06 AM
  #177  
Dave Harmon
 
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Originally Posted by vatechguy3
Got my landing gear in.
Used a slightly different method. Will explain later when not on a phone.

Also, what material are you guys using between the wing and fuse to avoid rubbing?

Just about done with mine. Need to install wheel pants, wheels, tailwheel, then balance and glue in battery tray where it is needed.
The finalize radio setup.

Would love to maiden this weekend. Have a contest next weekend at the FARM club.

Tony
Sounds good Tony.

I do not use anything in between the wing, stabs and fuse to avoid abrasion as there is no vibration.
The stab should not be dragging on the fuse anyway so nothing needed there.

Keep in mind that the Falcon gear legs (and pants if used) are considerably lighter than the BJ legs.
This will affect the c/g considerably so consider planning ahead for the c/g location.

I think you said earlier that you had an aftermarket battery tray.....so do I.
This tray IMO is too short and does not allow much battery movement.
This means that the tray location will have to be more accurate to allow for this lack of movement ability.
Uhhh....but where IS the c/g?
It depends on your flying style....but I can tell you for sure that it will be grossly tail heavy if you put that tray in the mfgr location.

Because it is much too tail heavy to begin (with the tray in the mfgr position and BJ gear legs) you should plan on installing the tray forward.
The front edge of my tray (same mfgr as yours) is 2" fwd of the l/g plate leading edge......and it should be further forward than that.
I suggest that the tray should be abt 3" fwd of the l/g plate...this is because of the much lighter Falcon gear and the mfgrs position too far aft to begin with.

I find it difficult to check the c/g on these airplanes because the wings are lightly built so it is risky to put some device under the wings and have the gross weight on 2 small points that might punch through the wing surface.
On solid wings or composite wings I use a board with 2 pencils pressed into holes....then the erasers become the balance points.

On the BJ airplanes I use a 1/8" music wire through both wing capture bolts, then slid the wings on and lift up on the wire in the center of the fuse.
This method is not accurate for sure but measuring this way will get you in the ball park so you can fly it and move the battery to trim properly.
The nose should fall when lifting on the wire (ready to fly with the canopy removed for access)....indicating that the c/g is somewhat fwd from the hole.

It is better to be nose heavy with the battery all the way aft...you can always add 1/4 oz at a time on the tail if needed.
The c/g adjustment becomes much more sensitive as the teeter point is approached....and the tail moment arm is much longer than the nose arm so small amounts of battery movement or weight on the tail will make large(r) changes.
The battery tray IMO needs to be at least 1" longer for greater c/g adjustability.

I do not know where my c/g is....only that I kept moving the battery until it flew correctly with no mixes.
I should also add that the above comments are considering use of the Falcon carbon spinner and Falcon carbon props.
If you use APC props.....all bets are off as they are great props but weigh a ton...no...6 tons for our use!
Great airplane!!

Dave

Last edited by Dave Harmon; 05-12-2016 at 08:17 AM.
Old 05-13-2016, 04:06 AM
  #178  
vatechguy3
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Checking balance now.
Yes i have a falcon carbon prop and spinner. And the falcon LG legs, along with some aftermarket carbon wheel pants a friend gave me. The pants are a little bigger and i am using 3inch MPI wheels. We fly off grass, so i need a little extra clearance.

230mm back from the leading edge of the wing is right on the leading edge of the t-can.

Picking up at that tcan leading edge, with the leading edge of the batts at the LG former, i balance slightly nose down.





Tony
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Last edited by vatechguy3; 05-13-2016 at 04:21 AM.
Old 05-13-2016, 06:45 AM
  #179  
vatechguy3
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Agree with your point on the battery tray. Would like it to be 50% longer with a 3rd carbon rod and another velcro slot. Would offer much more adjustability.

Tony
Old 05-13-2016, 07:20 AM
  #180  
Dansy
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Yes tray seem short, I'm installing a Gator battery tray in mine.

question about the rudder control horn is the slot already done....there's a few layer of covering so I can't feel it, I'm guessing I need to do it, just want To check first...
Old 05-13-2016, 07:31 AM
  #181  
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Originally Posted by vatechguy3
Agree with your point on the battery tray. Would like it to be 50% longer with a 3rd carbon rod and another velcro slot. Would offer much more adjustability.

Tony
I tried to determine the c/g holding the fuse at the l/e of the T-Can but the airplane becomes a pendulum using this method. Not good.

Looking at your pictures.....hopefully you don't mind if I make some suggestions.

The ESC needs to be MUCH further forward and in a vertical position for better cooling on the heat sink and for getting it's weight forward.
Please consider re-positioning it or you will likely have to add weight to the nose even with the battery fully fwd.

There have been several losses of the canopy using the BJ latch method.
IMO....BJ has the slot on the canopy tabs reversed.
The slot should be facing aft to not allow the rod to come out of the slot if the rear of the canopy rides up due to internal air pressure.
Some guys thought that the exhaust openings were not large enough and the internal air pressure got too high which tends to blow off the canopy....but, I have used a 'Best' latch on the last 4 airplanes without any problems whatsoever. Mike has had them in the past.
I like the ability to operate the latch with one hand.

Attached are some pix.

Dave
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Last edited by Dave Harmon; 05-13-2016 at 07:43 AM. Reason: Add Pix
Old 05-13-2016, 07:52 AM
  #182  
vatechguy3
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Thanks for the suggestions Dave.
But im not sure i follow you.

With the motor batteries in the position shown, the plane appears to balance correctly. I will check the balance again via wing position when i get home from work, but even if it needs nose weight, i can simply move the batteries forward 6, 8, 10 inches. So why move the esc for balance?

I still have to install cooling baffles for the esc and cut all the air acess holes. Those should cover me from a cooling perspective.

I did realize that i do still have to install the tail wheel, which should change things slightly since the tail moment is so long.

Also still have to install the receiver and receiver battery, but those will mount pretty much on the CG.

So biggest queston, is 230mm the correct CG? I need to start somewhere.

Tony
Old 05-13-2016, 08:09 AM
  #183  
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Originally Posted by vatechguy3
Thanks for the suggestions Dave.
But im not sure i follow you.

With the motor batteries in the position shown, the plane appears to balance correctly. I will check the balance again via wing position when i get home from work, but even if it needs nose weight, i can simply move the batteries forward 6, 8, 10 inches. So why move the esc for balance?

I still have to install cooling baffles for the esc and cut all the air acess holes. Those should cover me from a cooling perspective.

I did realize that i do still have to install the tail wheel, which should change things slightly since the tail moment is so long.

Also still have to install the receiver and receiver battery, but those will mount pretty much on the CG.

So biggest queston, is 230mm the correct CG? I need to start somewhere.

Tony
That's right....you have to start somewhere...that's what I meant by.."where IS the c/g"?

I'll re-word several things....

The airplane is tail heavy to begin with at the mfgrs suggested c/g....because his flying style is totally different.
We don't fly around with the tails hanging down and we only use a mixer as a last resort.
By 'we'...I mean US pilots.

Next....you removed the heavy BJ gear legs and installed Falcon gear which is much lighter.
This made it even more tail heavy.

Just to cut to the chase....you just have to move everything as far fwd as you can to get within battery movement range using that short tray.
Obviously....this is much easier to do before you install the tray....hence the reason for my pix and comments.
As I said previously...my tray should be at least 1 or 2" fwd of the pix....my battery hangs off the front of the tray about 1/2" to allow the plane to fly with no mixers.

Cooling the ESC....if it is laying flat I doubt if there will be enough air flowing over it even when you cut some holes.
I think you should move it fwd and mount it vertically.
The ESC in my pix is the OS 1100 or Futaba MCxxx.....works great...no computer/drama.
My receiver battery is mounted at the rear of the tray...the red Velcro holds it down.

Dave
Old 05-13-2016, 08:47 AM
  #184  
vatechguy3
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I see your point now. I was "assuming" the 230mm was a good balance point, not tail heavy at all.

So based on your pics and your descriptions, you think the battery tray should be centered over the landing gear former?

I will look at the esc mount tonight. A little worried about the length of the mezon and it interferring with the batteries if mounted vertically. But will try it out.

What are the flying characteristics at your current balance point? How much elevator is required for inverted flight? How does it track on 45 up and downlines?

Thanks
Tony
Old 05-13-2016, 09:03 AM
  #185  
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Originally Posted by vatechguy3
I see your point now. I was "assuming" the 230mm was a good balance point, not tail heavy at all.

So based on your pics and your descriptions, you think the battery tray should be centered over the landing gear former?

I will look at the esc mount tonight. A little worried about the length of the mezon and it interferring with the batteries if mounted vertically. But will try it out.

What are the flying characteristics at your current balance point? How much elevator is required for inverted flight? How does it track on 45 up and downlines?

Thanks
Tony
Because the tray is so short....you (we) don't have enough space available to make large changes...so the equipment and tray must be mounted close enough to some point that is designated as 'the c/g'....to allow the airplane to fly right.
Later today I will assemble the thing and try to get a measurement so you can get as close as you can.

I don't remember where the '230mm' measurement is taken from....please remind me....PM is ok or straight email.

I don't try to 'measure' the amount of down elevator for inverted level flight although I do hold a small amount of stick on it to avoid inverted 'ballooning'.
I adjust the inverted feel to more or less match the upright feel by adjusting the down expo only.....most modern transmitters are capable of this.
IOW....removing expo from the down elevator only....makes the ele move more for a given stick movement.

edit...I like the way the flying stab feels more than a conventional stab/ele.

Dave

Last edited by Dave Harmon; 05-13-2016 at 09:08 AM.
Old 05-13-2016, 09:29 AM
  #186  
vatechguy3
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Thanks for the help Dave
Email sent.

Tony
Old 05-16-2016, 08:20 AM
  #187  
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So, did it fly yesterday?
Old 05-18-2016, 09:21 AM
  #188  
vatechguy3
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She flies.
Still working on fine tuning and dialing in my setup.

Tony
Old 05-26-2016, 11:01 PM
  #189  
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I am sure we have talked about this, but any good suggested setups for throttle curves?

Br David
Old 05-31-2016, 09:51 AM
  #190  
Anthony-RCU
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Originally Posted by Daveeast
I am sure we have talked about this, but any good suggested setups for throttle curves?

Br David
Really simple. Start with 50% power at 25% throttle and then fine tune from there. Most E-set ups will feel a little dead off of the bottom and this will get you started.
Old 05-31-2016, 10:05 AM
  #191  
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Any good battery suggestions, recently been thinking about TP Magna 70C 5000s, the chemistry seem to hold up well particularly as my environment is so hot ( Dubai summer 40-50C) Obviously we fly early morning to avoid extreme heat. Having said that the one set I currently have are very new.

How do F3A Unlimited batterys last or the 10s Max Amp packs, any feed back welcome?

Cheers Dave
Old 06-01-2016, 11:10 AM
  #192  
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The F3A unlimited batteries are the best and lightest I own, they last longer then most as well going on 3 years on the first set I got to try them.... but I don't fly in the heat as you do.....my new 5400 are even lighter then 5100 mAh
Old 06-01-2016, 11:12 AM
  #193  
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Daniel

Thanks for the information, maybe give them a go.

Cheers D
Old 06-03-2016, 04:05 AM
  #194  
vatechguy3
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Has anyone cut the rear wing carbon dowel in half so you can adjust each wing incidence separately?

Tony
Old 06-03-2016, 04:24 AM
  #195  
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I have done that with all my BJ planes. I use 4 wing adjusters not just 2. You just have to adjust them proportionally. If you are using the Gator style (screw adjust) About 2/3 a turn on the front to full turn on back.
Old 06-08-2016, 09:21 PM
  #196  
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Rear Stab fences or not?

D
Old 06-09-2016, 08:49 AM
  #197  
vatechguy3
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Have not put them on mine.

Tony
Old 06-09-2016, 09:35 AM
  #198  
Dansy
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Neither did I, but if remember AJ told me I should when I talk to him at the Toledo show.....I just want to fly a little without and then put them and see the difference....
Old 06-09-2016, 09:47 AM
  #199  
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I have flown without, but will we gain with them??

D
Old 06-09-2016, 12:40 PM
  #200  
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Originally Posted by Daveeast
I have flown without, but will we gain with them??

D
Perhaps.....
The Nuance and other planes with the much smaller empennage are/were a bit directionally unstable so when I put the fences on there was a large improvement.
The G2 airplanes that have a huge empennage are much more directionally stable so I imagine that there will not be such a big improvement.
I have not put them on my Essence.....

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