BJ Craft Navigator
01-31-2024, 02:18 AM
#1
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BJ Craft Navigator
I am setting up the BJcraft Navigator. Does anyone have any information on the recommended CG. I am not able to find any information on this on the net. Thanks for the information.
03-09-2024, 01:44 PM
#2
My Feedback: (3)
This is the information I received from BJ Park via email …
CG:
CG range of this plane is very wide. as it is most swept wing
maiden flight CG is 40mm from the back of the main wing pipe (back not center)
This is nose heavy setting for safety. it can be extended to 60mm.
find the most rear point as long as you can. ( find tail heavy setting)
The key point is the length of servo arm, within 10mm.
Longer arm shall give you tail heavy feeling but actual is nose heavy.
When 45dgr vertical and slow half roll, find CG no heading drop without control.
CD:
The effect of most swept wing, single prop no need side thrust.
Large diameter(23~24 inch) single prop need 0.5 dgr.
This plane is able to use both single and contra prop, as side thrust is zero.
If use single prop, side thrust is 0 or 0.5 dgr.
so it was zero dgr in production model.Using both propulsion has no problem.
Maiden flight incidence:
Min wing 1 dgr. full flying stab zero.
Canal incidence is -3dgr~+3dgr. little effect to flying.
Decide CG and wing incidence then as you like same as flying stab or wing.
CG:
CG range of this plane is very wide. as it is most swept wing
maiden flight CG is 40mm from the back of the main wing pipe (back not center)
This is nose heavy setting for safety. it can be extended to 60mm.
find the most rear point as long as you can. ( find tail heavy setting)
The key point is the length of servo arm, within 10mm.
Longer arm shall give you tail heavy feeling but actual is nose heavy.
When 45dgr vertical and slow half roll, find CG no heading drop without control.
CD:
The effect of most swept wing, single prop no need side thrust.
Large diameter(23~24 inch) single prop need 0.5 dgr.
This plane is able to use both single and contra prop, as side thrust is zero.
If use single prop, side thrust is 0 or 0.5 dgr.
so it was zero dgr in production model.Using both propulsion has no problem.
Maiden flight incidence:
Min wing 1 dgr. full flying stab zero.
Canal incidence is -3dgr~+3dgr. little effect to flying.
Decide CG and wing incidence then as you like same as flying stab or wing.
04-06-2024, 05:24 AM
#6
Hello,
I have the Navigator and am just starting the build. This is the first build of this type for me. Lots of experience with standard wood kits but nothing.like this.
Really the big difference for me is mounting the motor.
I a using the dualsky CRS3000 contra system.
I cannot use the rubber isolation mounts they provided because there isn't enough room to get a firewall in and have a gap for the spinner.
After going over it with my local building mentor (Thanks Dan) I will hard mount it.
I will also be beefing up the landing gear mount per some BJ Build threads.
The only issue with the kit at this point is I just discovered on aileron is badly warped, is has a big bow in it. Not sure how to straighten it out without tearing the covering off.
I have reached out to see if I can get a replacement.
Thanks for posting the info from BJ!
My elevator horn is more like 50mm from the elevator to the hole.
All in all cant wait to get it in the air!
I have the Navigator and am just starting the build. This is the first build of this type for me. Lots of experience with standard wood kits but nothing.like this.
Really the big difference for me is mounting the motor.
I a using the dualsky CRS3000 contra system.
I cannot use the rubber isolation mounts they provided because there isn't enough room to get a firewall in and have a gap for the spinner.
After going over it with my local building mentor (Thanks Dan) I will hard mount it.
I will also be beefing up the landing gear mount per some BJ Build threads.
The only issue with the kit at this point is I just discovered on aileron is badly warped, is has a big bow in it. Not sure how to straighten it out without tearing the covering off.
I have reached out to see if I can get a replacement.
Thanks for posting the info from BJ!
My elevator horn is more like 50mm from the elevator to the hole.
All in all cant wait to get it in the air!
07-03-2024, 04:34 PM
#7
I am just about set for my maiden flight.
In checking the CG. I need to put the batteries behind the landing gear to get the 40mm behind the rear of the wing tube per BJs info above.
Wondering if anybody has flown their navigator and what their set ups are for control throws and such.
Thanks
Kevin
In checking the CG. I need to put the batteries behind the landing gear to get the 40mm behind the rear of the wing tube per BJs info above.
Wondering if anybody has flown their navigator and what their set ups are for control throws and such.
Thanks
Kevin
07-11-2024, 04:15 AM
#8
Maiden Flight
I have finally gotten the maiden in.
I was very nervous about this one. A lot of firsts in it for me.
First flight with a Contra, first flight with a flying stab and first flight with a plane costing so much.
Also coming off a crash that destroyed my Episode, and my buddy crashed his new pattern plane.
The maiden went of just fine with very little trim required.
A pretty strong wind came up right after take off so it was difficult to really tell.
The stab was set pretty close set it about the same as the wing and needed a few clicks of down trim.
The CG was set to 40mm behind the rear of the main tube as suggested.
The flight was short at about 3 min to get a feel for the battery usage. Used only 30% of the 5200mah battery.
The Dualsky CRS 3000 contra drive put out plenty of power on 10S.
The motor was hot after the flight - I noticed on the run up test that it got pretty warm also.
Batteries were not even warm.
The pitch response was different and I can only describe it as mushy and I will be be adding in a bit more throw especially up.
Hoping to get a few more flights on it tomorrow and fly it in our clubs contest this weekend!
I was very nervous about this one. A lot of firsts in it for me.
First flight with a Contra, first flight with a flying stab and first flight with a plane costing so much.
Also coming off a crash that destroyed my Episode, and my buddy crashed his new pattern plane.
The maiden went of just fine with very little trim required.
A pretty strong wind came up right after take off so it was difficult to really tell.
The stab was set pretty close set it about the same as the wing and needed a few clicks of down trim.
The CG was set to 40mm behind the rear of the main tube as suggested.
The flight was short at about 3 min to get a feel for the battery usage. Used only 30% of the 5200mah battery.
The Dualsky CRS 3000 contra drive put out plenty of power on 10S.
The motor was hot after the flight - I noticed on the run up test that it got pretty warm also.
Batteries were not even warm.
The pitch response was different and I can only describe it as mushy and I will be be adding in a bit more throw especially up.
Hoping to get a few more flights on it tomorrow and fly it in our clubs contest this weekend!
07-12-2024, 12:47 AM
#9
Congratulations on your successful maiden.
With regard to your comment on mushy feeling pitch response, everything I have heard & read about all flying stabs is the need for much less expo than a conventional elevator stab.
40-50% Expo on the elevator in normal flying mode is typical whereas an all flying stab will be less than 20% to get the same feel, perhaps this is a factor in your mushy feel.
Steve
With regard to your comment on mushy feeling pitch response, everything I have heard & read about all flying stabs is the need for much less expo than a conventional elevator stab.
40-50% Expo on the elevator in normal flying mode is typical whereas an all flying stab will be less than 20% to get the same feel, perhaps this is a factor in your mushy feel.
Steve
07-13-2024, 07:48 AM
#10
So I own two Akiba designs with all moving tails. A Navigator and an Epsilon bipe.
Having read previously about amts not requiring much expo I started off on the Epsilon with only about 20% but found this incredibly “jumpy” I increased expo in stages and ended up with 50% up and 53% down as I normally set about 10% more down movement than up.
On the Navigator I started with 50/53% from the get go and find this to be perfect to give the slightly dead feel I prefer in my pitch control. At the end of the day you need to find what works for you so don’t feel the need to slavishly follow what you read.
Malcolm
Having read previously about amts not requiring much expo I started off on the Epsilon with only about 20% but found this incredibly “jumpy” I increased expo in stages and ended up with 50% up and 53% down as I normally set about 10% more down movement than up.
On the Navigator I started with 50/53% from the get go and find this to be perfect to give the slightly dead feel I prefer in my pitch control. At the end of the day you need to find what works for you so don’t feel the need to slavishly follow what you read.
Malcolm
07-14-2024, 01:58 AM
#11
Malcolm,
Of course actual flying experience is what really counts. As you and I say flying reports of planes with AFT say the same thing, less expo required, no idea why this would be so prevalent yet you found it not to be true in practice. I've been building the Japanese Top stage kit for a while now (long term project !), they have elevator or AFT versions and show recommended Expos & throws (starting points) on an otherwise identical airframe the recommended expo on the elevator version is more than twice the AFT version. I recall a mutual friend of ours did prefer less expo on his biplane with AFT. End of the day with F3A the settings are largely down to personal preference I suppose.
Steve
Of course actual flying experience is what really counts. As you and I say flying reports of planes with AFT say the same thing, less expo required, no idea why this would be so prevalent yet you found it not to be true in practice. I've been building the Japanese Top stage kit for a while now (long term project !), they have elevator or AFT versions and show recommended Expos & throws (starting points) on an otherwise identical airframe the recommended expo on the elevator version is more than twice the AFT version. I recall a mutual friend of ours did prefer less expo on his biplane with AFT. End of the day with F3A the settings are largely down to personal preference I suppose.
Steve
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wattsup (07-14-2024)
07-15-2024, 09:30 AM
#12
Thanks Malcome and Steve for your input.
I am hoping to get it dialed in over the next couple of weeks.
I wanted to fly it this last weekend in our clubs pattern contest but the motor made a strange noise (maybe just prop noise) on the second flight so I just landed and used my backup.
I will be flying it in about 5 weeks in the next local contest.
Kevin
I am hoping to get it dialed in over the next couple of weeks.
I wanted to fly it this last weekend in our clubs pattern contest but the motor made a strange noise (maybe just prop noise) on the second flight so I just landed and used my backup.
I will be flying it in about 5 weeks in the next local contest.
Kevin
The following users liked this post:
wattsup (07-15-2024)
07-15-2024, 06:24 PM
#13
Senior Member
So I own two Akiba designs with all moving tails. A Navigator and an Epsilon bipe.
Having read previously about amts not requiring much expo I started off on the Epsilon with only about 20% but found this incredibly “jumpy” I increased expo in stages and ended up with 50% up and 53% down as I normally set about 10% more down movement than up.
On the Navigator I started with 50/53% from the get go and find this to be perfect to give the slightly dead feel I prefer in my pitch control. At the end of the day you need to find what works for you so don’t feel the need to slavishly follow what you read.
Malcolm
Having read previously about amts not requiring much expo I started off on the Epsilon with only about 20% but found this incredibly “jumpy” I increased expo in stages and ended up with 50% up and 53% down as I normally set about 10% more down movement than up.
On the Navigator I started with 50/53% from the get go and find this to be perfect to give the slightly dead feel I prefer in my pitch control. At the end of the day you need to find what works for you so don’t feel the need to slavishly follow what you read.
Malcolm
I fly the AKIBA Interceptor with All Flying Stab and I use No expo ......The feel is very linear
Adding 20 % Expo makes no difference and I think the idea is to use a good quality servo with high torque and a short servo arm.
