Desert Fox 1

Hello All,


Cheers!
Desert Fox 1

Desert Fox 1

Hello All,


Cheers!
Desert Fox 1

dccatl

My Feedback: (1)

Thanks to Rommel (aka Desert Fox) for the great video coverage for the maiden flights. For anyone interested: control throws were per Dave Wilshere's post (#14) earlier in this thread, as was C/G (180 mm from leading edge). Take off with no flaps, required a good bit of up elevator trim at level flight and a good bit of down for each flap setting (8mm crow on landing flap). I'll take measurements on the trim amounts tonight and post back. No aileron trim required. Plane handles the 100xbl nicely, both flights were with timer set at 4:30 and landed with about 1/2 tank of fuel with throttle about 50-60% most of the flight. I will start to calibrate the pump factor in my Xicoy FC1 computer on the next outing. Still working on getting gyro gain set on the Cortex Pro, 2nd flight ended with about 35% and I think it could take 5-10 points more, will fine tune on subsequent flights, however the plane flies very stable and I didn't really notice the absence of a gyro on the first flight which had about 5-7 mph winds straight down the runway. Plane does slow down nicely for landing, especially given the rather small flaps. Looking forward to getting some more stick time on it in the coming weeks (weather permitting) and squaring up those landings with the runway a little better.

Dave Wilshere

Did you do a power on/off test to check thrust line?
I always take off with some flap, needing lots of down with flap is true of the Joker and Ultra Flash platform.
Did you balance at 180mm with some fuel in the main tank? Half a tank is 2lb of fuel so you will slow even more when landing at a normal fuel level.

Dave

dccatl

My Feedback: (1)

No, but that's a good idea, will check next flight. So let me ask you this: I mounted the pipe per CARF's recommendation, flush with the top of the fuse at the exit with eccentric spacers around the bottom and sides. Front of the pipe had the carbon bell mouth flush against the former on the rear of the turbine mounting rails (as far toward the top of the fuse as it would go) then the turbine mount was shimmed a few mm with plywood shims to center it in the bell-mouth. So if the power on/off test shows it tucking down with power on, that would indicate too much down vectored thrust (pushing the tail up and the nose down), correct? If so, to correct I would need to angle the pipe and the turbine up some amount by lowering the bell-mouth (moving it away from the top of the former) and then lowering/angling the turbine mount slightly with slightly thicker shim in the front of the mount?

I debated this but went with no flap as it's my usual practice and didn't want something "new" (to me) on a maiden (my first of a turbine powered model by the way)

Yes, there was some residual fuel left in the main tank when I balanced, couldn't say exactly how much, about a half inch from the bottom of the tank maybe. I checked C/G on the 2nd flight by pulling a 45 degree up-line at mid throttle then rolling inverted, then hands off sticks and it held the up-line pretty well without pushing any elevator so I think C/G was pretty good.

Thanks,
David

Dave Wilshere

Sounds like the thrust line should be correct, but it’s still worth checking if you were flying with trim at constant speed.
when it’s a known design, I’ve never seen the concern of using flaps, even on unknowns I use it, and I have never been surprised. Your take off looked short enough, the Joker sits tail down so the wing already has lift.

As always these models need fine tuning to suit your thumbs, there are so many variables.

dccatl

My Feedback: (1)

Well I guess my term "good bit" was somewhat relative. I just measured the trim adjustments and I have 1 mm of up with no flaps, 2 mm of down for take-off flaps and 7.5 mm of down on full flaps (with 8 mm aileron crow at the root).

setxws6

Anyone know the size of the stock tank, diameter and length?

Dave Wilshere

It’s a little bit over 2 ltrs. Don’t have the sizes here

Bob_B

My Feedback: (11)

What servo fits the Nose Gear steering mount?

dccatl

My Feedback: (1)

I used the Graupner SJ HVC 660BB but I had to file the edges of the servo mount slightly with a flat-file to get them to go in easily.

setxws6

Has the retracts, gear and retract controller been working well for all that have the Joker?

dccatl

My Feedback: (1)

In my limited experience (2 flights), yes. I also cycled them numerous times during the build and they worked fine, never missed a beat. If it ever warms up here in "Hotlanta" I hope to get more flights in on it.

markbrown65

No problems on mine.

Mark

Dave Wilshere

I've flown two now and the retracts have been faultless. Mark's probably has the most flights other than CARF's original

Bob_B

My Feedback: (11)

I have the same gear in my L39 and with 6 flights it has been flawless. The AVANTI XS uses the same and two friends are flying that model with zero gear issues

setxws6

Ok thanks for the input guys. I've had DreamWorks and Behotec controllers that have performed flawless, but recently had a Pilot retract controller that came with my Pilot Dolphin and it failed to lower the gear for me last week while on my third flight!!! Replaced it with a DreamWorks controller. Thinking about getting a Joker this year and was curious since it comes with it's own controller too.

Bob_B

My Feedback: (11)

I will say the brake controller is seperate on my L39 Gear set. It is not proportional in response. The radio epa only determines the max brake force. I set up a sequencer to prevdnt the brakes from locking and flat spotting the tires. Im guessing the Joker is similar.

dccatl

My Feedback: (1)

Bob is right, the controller is not proportional, I adjusted my end-points in the transmitter and managed not to flat spot my tires by careful and very quick brake application. The controller that came with my Joker is all in one by JP, has gear and brakes in one case as well as two door sequencer outputs (not used on the Joker) - there is only 1 power input which can handle up to 8.4 volts.

I may try this brake controller from Xicoy for better proportional braking:

https://www.xicoy.com/catalog/produc...40e22ee53d4067

Bob_B

My Feedback: (11)

Great find, i wonder if Dreamworks stocks it?
If not I understand Gaspar ships fast.

Dave Wilshere

No such thing as proportional braking when you have a contact patch 5/8" x 3/8" I just set the brakes not to lock and they will work great.
The green Joker I flew had the later all in one and braking was fine on wet tarmac

Bob_B

My Feedback: (11)

Electric Brake Controller

Dave Wilshere

The new PnP version of the Joker is available to order now.
https://carf-models.com/en/products/...np/parent/4095

LewisE1

Got some flights on my green joker this week (weds and today) after Dave test flew it a couple of weeks back, its a pretty fun jet, no drama's to fly, landing has been perfect with a little crow mixed (5mm), used the settings on here for the surfaces, I have a gyro3e set up and at the moment its set at 27% and seems very solid at that, I may try the gps2 on it at some point or have a offset to increase the gain for landing mode, will see, the expo on the ailerons feels good even with the gyro 35%, elevator I have trimmed back to 20% and the same on the rudder, still early days with the model but it feels very balanced like that.

setxws6

Not a bad deal considering with servos everything installed. And a new color added!!! Think I still like the yellow, but that red though....