CARF Joker build thread
#752

Hi,
Mine is ready to be maidened, as soon as the Belgian gouvernement allows model airplanes back in the air.
This is excpected in 2 weeks from now😁😁😁
Balanced the Joker @185mm from the fwd middle part of the wing, being 28mm from the axle of the main wheels.
With all 3 batteries under the radome, 170grams would have been required in the tail, way to much.
Therefore, i moved the turbine battery under the cockpit, which gave me a gaan of 120grams. So, now i have still 50 grams of lead.
So, at the CG, as recommended by Dave, including 300ml of fuel in the tank (min landing fuel), the Joker’s weight is 7950grams.
Can’t want to take here in the air😃
Any tips for t/o and landings?
Just ordered a subtile set of decals for the jet....
Regards,
Eric
Mine is ready to be maidened, as soon as the Belgian gouvernement allows model airplanes back in the air.
This is excpected in 2 weeks from now😁😁😁
Balanced the Joker @185mm from the fwd middle part of the wing, being 28mm from the axle of the main wheels.
With all 3 batteries under the radome, 170grams would have been required in the tail, way to much.
Therefore, i moved the turbine battery under the cockpit, which gave me a gaan of 120grams. So, now i have still 50 grams of lead.
So, at the CG, as recommended by Dave, including 300ml of fuel in the tank (min landing fuel), the Joker’s weight is 7950grams.
Can’t want to take here in the air😃
Any tips for t/o and landings?
Just ordered a subtile set of decals for the jet....
Regards,
Eric
Last edited by Speedrick; 04-28-2020 at 04:27 AM.
#756

Thread Starter

Yes, I understand that. Danny’s is lighter than yours and I expected the Electrons and gizmo to add a few grams over ‘ normal’
My ‘minimal’ version was just on 7kg dry.
My ‘minimal’ version was just on 7kg dry.
#757


With all this talk about weights I was curious how accurate my own scales really are. I primarily use the Digitech CG Wizard but also have one of the earlier sets of Xicoy scales. Using a trio of 300g calibrated weights that we use for servicing the CG Wizards I did a comparison between it, the Xicoy, and couple of digital scales we typically use for mixing resin. As you can see they are all pretty close.




Since 900g is not nearly the typical jet weight I also did a cross check using a 50 lb shot bag. For this I used our shipping scale as well as an old bathroom scale. As you can see the results are pretty consistent at the higher weights too.




I repeated these tests 4 times each and every time the results were within a few grams on the low end and 50 grams on the high end. Certainly accurate enough for our models. I’d boil for tea with any of them




Since 900g is not nearly the typical jet weight I also did a cross check using a 50 lb shot bag. For this I used our shipping scale as well as an old bathroom scale. As you can see the results are pretty consistent at the higher weights too.




I repeated these tests 4 times each and every time the results were within a few grams on the low end and 50 grams on the high end. Certainly accurate enough for our models. I’d boil for tea with any of them

Last edited by F1 Rocket; 04-28-2020 at 12:54 PM.
#759

My Feedback: (10)

With all this talk about weights I was curious how accurate my own scales really are. I primarily use the Digitech CG Wizard but also have one of the earlier sets of Xicoy scales. Using a trio of 300g calibrated weights that we use for servicing the CG Wizards I did a comparison between it, the Xicoy, and couple of digital scales we typically use for mixing resin. As you can see they are all pretty close.


Since 900g is not nearly the typical jet weight I also did a cross check using a 50 lb shot bag. For this I used our shipping scale as well as an old bathroom scale. As you can see the results are pretty consistent at the higher weights too.
I repeated these tests 4 times each and every time the results were within a few grams on the low end and 50 grams on the high end. Certainly accurate enough for our models. I’d boil for tea with any of them


Since 900g is not nearly the typical jet weight I also did a cross check using a 50 lb shot bag. For this I used our shipping scale as well as an old bathroom scale. As you can see the results are pretty consistent at the higher weights too.
I repeated these tests 4 times each and every time the results were within a few grams on the low end and 50 grams on the high end. Certainly accurate enough for our models. I’d boil for tea with any of them

tsk tsk tsk the Xicoy is off ;-)..
#760

I have been out flying my Joker recently and have found that when retracting my landing gear sometimes the left main does not fully retract. Upon inspection I have discovered the left main strut does not extend all the way out, the spring has become a little weak after 80+ flights. Has anyone else come across this issue and if so what was your solution? Oh yeah, it is the JP Hobby gear that comes with the kit and I have not had any harsh landings.
I came across this: https://www.turbines-rc.com/en/strut...mm-length.html but it says hard spring so I am not sure if this is the stock spring or a beefier spring. I don't need a beefier spring. the current dampening rate has been great.
I came across this: https://www.turbines-rc.com/en/strut...mm-length.html but it says hard spring so I am not sure if this is the stock spring or a beefier spring. I don't need a beefier spring. the current dampening rate has been great.
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#766

Thread Starter

Just seen this posted by Essential Rc. Higher energy flight than I would normally fly with the Joker, I like to show it flies great at slower speeds-I guess that flight I was asked how it performed at higher speeds-still no full power stuff
#768

Thread Starter

Bob, thanks, I normally fly bigger ‘open’ style flights but the guy with me was interested in a Joker and has limited airspace, so wanted to see if it would turn and burn 🙂
#769

OK!!!!!!
Tomorrow will be the big moment.
Got finally the club approval to maiden my Joker.
any last minute tips for the first take off and landing?
Regards,
eric
Tomorrow will be the big moment.
Got finally the club approval to maiden my Joker.
any last minute tips for the first take off and landing?
Regards,
eric
#770

Thread Starter

How long is your landing area? Rotation is really easy, take off with a little flap. Holding a small back pressure on the elevator through the take off roll it will just take off, keep the climb out constant and smooth.
Full flap needs the down elevator trim setting. The flaps are not huge, so it slows gradually, touch down can be at a very low speed.
Just don’t force it onto the ground, let it land.
You will be fine.
Full flap needs the down elevator trim setting. The flaps are not huge, so it slows gradually, touch down can be at a very low speed.
Just don’t force it onto the ground, let it land.
You will be fine.
#772

I had few flam out with mine and I was able to land safely( igniter problem) this is a very stable model .who keep is energy very well..a bit nose heavy for the first minute after its fine when tank start to empty ...I love mine , fly like a dream and like Dave the expert said ; ; : : land very slow.
Good luck and enjoy
Good luck and enjoy
#774

Thread Starter

Eric
Perfect, we operate from 120m and guys with only some experience cope with this length of runway
Just remember, after the second turn you must be breathing 😉
Dave
Perfect, we operate from 120m and guys with only some experience cope with this length of runway
Just remember, after the second turn you must be breathing 😉
Dave
#775

Hi guy’s,
Maidenend my Joker today, what a beauty to fly!!!!
Although there was no wind..... landing the jet with a mix of flaps and aileron, acting as spoilers,
the airplane pitched up automatically, so that I only had to touch the up elevator,upon touchdown.
After flying model airplanes for 40years, I felt like a 20 year old afterwards😉
The only remark were the brakes, they applied asymmetrical when I needed them...
Looking so forward to the next opportunity to fly the Joker!
Kind Regards,
Eric
Maidenend my Joker today, what a beauty to fly!!!!
Although there was no wind..... landing the jet with a mix of flaps and aileron, acting as spoilers,
the airplane pitched up automatically, so that I only had to touch the up elevator,upon touchdown.
After flying model airplanes for 40years, I felt like a 20 year old afterwards😉
The only remark were the brakes, they applied asymmetrical when I needed them...
Looking so forward to the next opportunity to fly the Joker!
Kind Regards,
Eric