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JET LEGEND VIPER BUILD THREAD

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Old 07-21-2012, 02:09 PM
  #76
Jeremy_D
 
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Default RE: JET LEGEND VIPER BUILD THREAD

Congratulations Ceffi on your flights!!

With the lead removed from the nose, how far back is the c.g from the original location?
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Old 07-21-2012, 08:48 PM
  #77
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Default RE: JET LEGEND VIPER BUILD THREAD

Hi guys,
Good news.
JL viper jet electric retracts test finish one week ago,Of course also includes electronic brake.
My friends and Iwas glad to help the test.Factory will release soon.

electric retracts video:http://v.youku.com/v_show/id_XNDI4NTQ5OTYw.html

William
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Old 07-21-2012, 09:56 PM
  #78
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Default RE: JET LEGEND VIPER BUILD THREAD

Quote:
how far back is the c.g from the original location?
Hi Jeremy,
For the first flight the Viper was light noseheavy.

I will check next flight.
I removed first the half of the led and now all.
No flight without all the led, but should be good.

Christian
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Old 07-22-2012, 01:04 PM
  #79
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Default RE: JET LEGEND VIPER BUILD THREAD

Guys,

A friend has already had multiple flights on his and he has moved the CG back 35mm from the original position. Flies bery well at that apparently.

Jeff
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Old 07-22-2012, 09:58 PM
  #80
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Default RE: JET LEGEND VIPER BUILD THREAD

Congratulations Christian.

Yes factory setting is too nose heavy. We moved it back.

Mike
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Old 07-29-2012, 05:22 AM
  #81
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Default RE: JET LEGEND VIPER BUILD THREAD

Hi guys,
The latest flight video sharing.
Fun flight in my trip.

video 1:
http://www.tudou.com/programs/view/IXlYDoV_m2U/
videl 2:
http://www.tudou.com/programs/view/jB1k11YZEOc/

Regards
William
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Old 07-30-2012, 09:04 AM
  #82
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Default RE: JET LEGEND VIPER BUILD THREAD



Hi Guys

Ive now had 23 flights with my Viper TL12 combo over the last few weekends and thought I would confirm the settings Ive given Jeff at Zedjet regarding the CG im useing for the Viper
I am now at 36mm back from the centre of wing tube, Still got some up trim in and ive I have flown her in twice nowwith completely empty tanks and shes still rock steady.

Im useing a DX18 so if anyone wants to try my knife edge and flap comp setting ill post if you wish, there all but spot on now but may change as I go evan further back with the CG!

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Old 07-30-2012, 09:23 AM
  #83
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Default RE: JET LEGEND VIPER BUILD THREAD

Hi Again
Sorry if I'm playing catch up on this thread but i noted you guys have had i prob with hooking up the 2mm air lines.
Well i had the same issue but sorted it quite quickly buy simply pushing the line on to std fittings, every things stayed airtight so far.
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Old 07-30-2012, 09:24 AM
  #84
Ian Prentice
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Default RE: JET LEGEND VIPER BUILD THREAD

Thanks for the info hope to balance mine tonight so really helpful ! Quite a big difference ! it must have been really nose heavy ?
I got my merlin back today ! Got to say they take some beating in customer service ! I got it back within 2 weeks ! So glad I decided to switch to merlin from the uk equivalent ! Did you find the travels about right ? And have you used expo on elev Cheers Ian
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Old 07-30-2012, 09:27 AM
  #85
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Default RE: JET LEGEND VIPER BUILD THREAD

I have not tried it yet but im sure we can share model memories just by mailing the file on the memory cards in the DX18 Txs
Im willing to give it a go if any one is intrested.
I realise the throws and sub trims would need to be alterd but it might be helpfull?
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Old 07-30-2012, 10:18 AM
  #86
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Default RE: JET LEGEND VIPER BUILD THREAD

Just taken the basic settings from my Viper and DX18 Tx
Elevator is 16mm each way with 30% expo at full rate, fairly soft but enough for hard turns if you feel the need to pull the stick hard.
I am still flyingwith 3mm up trim with the CG 36mm back innorm flight at halfpower and if you aply full power it only then will start toclime.
Needs nearly 1/4 forward stick invertedto keep level.
Ailerons are 20mm each way with 30% expo at full rate , quite lively at full rate so I've been using 80% rate for norm flight
Rud 23mm each way and she will clime out of knife edge so 1/2 to 2/3 is enough for a pass
Rud to down Elevator for knife edge is 13%, might try a bit more but moving the CG might change that
Rud to opposite Aileron is 18%

Flap is 24mm for take off with 18% down Elevator but still needs a bit morebut thums are taking care of this small trim change at the moment.
Landing is set to 55mm with 5mm crow which slows it down really well, Ive got 22% down trim which seams about right
Ive also got a 4 sec delay to smooth it all out

Clean it takes an age to slow down and you run out of space waiting for it to slow enougth to try stalling it as its a very clean airframe, but the stall is straight and "mushy" it wont drop a wing
With the flap half down it realy hangs in there wont stall at all just nods, I did not push it any harder as it was so slow at that point it might have got a bithairy.
Landings are a joy and if you wish she will come in at well over 45 deg with out speeding up, flares nicely and will not balloon at all.
Once you get the wheels down on the deck she sticks tolike a limpet but oil up the brakes as the wheels are set wide and it can swing if you don't have a graduated brake valve.
With the Jetlegend T12 on board and 24mm of flap she will lift off in about 60-80 feet on tarmac and then go vertical if you feel the need, evan with all 3lt of fuel on board!
The Jetlegend/Spark T12 Turbine has got to be one of the best value 27lb turbines around, I've got well over 4 hours on it now and nearly 50 flightsand its never missed a beat
Its internal kero start that works first time every time. I get 9,1/2mins on 3lt with enough for a further 1,1/2 mins for go rounds (ive ran the tanks dry wile flying just to find out!)
The Viper is 22lbs dry so add another 6-7+ lbs for the fuel and at that weight I can clime vert from the ground as high as I can see all for only £1500, ask Jeff at Zedjet if you want one.
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Old 07-30-2012, 11:08 AM
  #87
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Default RE: JET LEGEND VIPER BUILD THREAD

Here is a pic of how I Have set up my flap linkages on the JL Viper.
I like to use std 3mm Kwik links as this allows me to keep the servo arms short and can use all 100% travel .
The links can also "disappear" into the slot with out having to make the slots very much wider so look nice and neat.
I first cut off the horn on the flap hinge and fixed a new epoxy glass one in line with the slot in the servo hatch.
The Flaps are hollow so used plenty of epoxy and micro balloons filling the area around the new slot.
The horns also placed further back to give better leverage at full down flap with out the pivot point riding over centre.
Seams to work well and I have managed to keep 100/95% servo travel and in flap settings use 88% for up, 0% for take off then 80% for landing.
If I had kept to the ball links I would have had to use much longer arms and reduced the servo travel halving there effective power.
Ether that or use short servo arms then cut large slots in the very nice hatches which seamed a shame as they look really neat
Threes nothing wrong with ball links and the JL ones supplied are very good but i did not feel they were called for here.
The same is true for the Ailerons and Rudder and I have used Kwik links there to.

I'm am sure the reason why flutterhas occured on some other fast airframes is were the servos are at a disadvantage.
We pay a fortune for good powerful servos,I try to get all 11kg usefull torkout of my JR 8421 servos were I can by useing at the very least 100% travel.
If youhave to set themas low as 50% of servo travel "for full control movement" you will only get1/2 the efective holding powerfrom them.
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Old 07-30-2012, 11:22 AM
  #88
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Default RE: JET LEGEND VIPER BUILD THREAD

Thanks for the settings, I've just received my missing fittings today so fingers crossed for the weather this weekend.
Using DX18 so your settings are useful for me,
Gary.

p.s. P80SE Power.
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Old 07-30-2012, 01:30 PM
  #89
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Default RE: JET LEGEND VIPER BUILD THREAD

Thanks for the info especially on the C.G. How slow can it be flown in with the new CG?

I got notification mine is ready to be sent from GJC today. I opted for the ARF Pro Wired version which is all the ext leads and airline pre installed. Going to be running a P80se in this. I'm looking forward to starting the build!
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Old 08-01-2012, 08:00 AM
  #90
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Default RE: JET LEGEND VIPER BUILD THREAD

Just been given some vids of my first day out with the Viper, bit shakey and a lot of wind noise but should give some idear of how she handels

http://www.youtube.com/watch?v=XML-iCg-_y0&feature=plcp

http://www.youtube.com/watch?v=wrLl7unmR68&feature=plcp

http://www.youtube.com/watch?v=wKZZ9LdbfNs&feature=plcp


Im no expert pilot but the Vipers steady evan in on a windy day and is very easy to land dispite the bumps.
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Old 08-01-2012, 01:34 PM
  #91
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Default RE: JET LEGEND VIPER BUILD THREAD

It certainly looks like it slows down very nicely with the CG pushed back. would you suggest 20mm back as a good starting point and then work back from there?
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Old 08-01-2012, 10:00 PM
  #92
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Default RE: JET LEGEND VIPER BUILD THREAD

Do you think the landing gear is suitable/robust enough for grass field operation.I know they`re trailing link but whats the quality like?With the T12 Turbine are you adding any nose weight? I was thinking a Jet Munts VT80 would be a good choice of turbine but is over a pound lighter than the T12.Would not want to start adding weight at the back![] This Jet is on my short list now for 2013 model
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Old 08-02-2012, 12:45 AM
  #93
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Default RE: JET LEGEND VIPER BUILD THREAD

Hi Jeremy

Itsstill very stable at 36mm back so 20-25 will be fine but be ready to trim the elevater back a bit to keep the nose up.
Ive have made it so I can move stuff around now so I will be creeping the CG further back this week end.
Dont expect and thing dramatic to happen but wish me luck
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Old 08-02-2012, 01:17 AM
  #94
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Default RE: JET LEGEND VIPER BUILD THREAD

Hi Steve


The Spark trailing link UC is very well made and has plenty of travel, its also air sprung so no springs to get weak or stretch.
Ive not been able to fly from our grass patch yet as we have ripe crops around but flying from grass is one of the main reasons I've bought the Viper

The VT80 will be ideal, your not going to get the silly vertical I'm getting with the 27+lb from the T12 but it cant hurt the handling if its a pound lighter.
I'm very sure it would fly very nicely with anything from an old P80,Wren Super Sport, K80 and be brilliant on the new Wren 100 or P100.

I did have 5-6oz of lead in the nose to start with but soon lost that along with its 2200 singel cel Lipo for the lights
I am now useing alighter Rx and ECU battery's and then moving stuff back to above and behind the tanks.
Theirs plenty of scope to shift gear, For a start I can move the Rx pack up to 400mm further back and could place the ECU pack on top of the duct or evan along side the turbine.
The T12 turbine its self centres 100mm behind the CG so its weight hasn't a huge effect on the overall CG and you still have the pump fro your VT80 you could fit rearward.
For those with heaver turbines, if needs be you could place weight as far forward as 800mm from the CG but should not need to.
With lighter turbines you couldput items as far back as the rear of the huge turbine bay.
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Old 08-02-2012, 01:27 AM
  #95
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Default RE: JET LEGEND VIPER BUILD THREAD

Thanks for the info,very helpful.
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Old 08-02-2012, 01:32 AM
  #96
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Default RE: JET LEGEND VIPER BUILD THREAD

Here is a pic of the T12 turbine first before I moved the valves back and then after tohelp with the new more rearward CG
The CG at the moment is more or less at the rear of the inlet duct as you see it in the pic.
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Old 08-02-2012, 01:32 AM
  #97
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Default RE: JET LEGEND VIPER BUILD THREAD

Agreed, excellent info, Looking forward to starting the build
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Old 08-02-2012, 01:41 AM
  #98
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Default RE: JET LEGEND VIPER BUILD THREAD



This might help, I originally made an under tray to hold the retract and brake valves along with the pump and turbines valves in an effort to get everything forward.
I like to place the pneumatics under the main tray out the way if i can as its hard to remove the main tray with lots of pipes etc attached at a later date.
The last pic is after I removed the Jetronic E-Valves and replaced them with a simpel Beotec C36 Brake-Retact valve and moved the pumpand turbines valves back toshift the CG.
You may note in the second pic I found room for a second air tank, Ive found it to be unnessersery as the retracts are very reliabel andget lots of cycels but it could be used for separate brake air?

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Old 08-02-2012, 01:48 AM
  #99
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Default RE: JET LEGEND VIPER BUILD THREAD

This is were I moved the tiny Xicoy V10 ECU and its battery too, The tray also doubels as a tank brace.
Theres plenty of room up there for any size ECU and if extenden over the inlet duct the wieght could go evan further back.
Be shure not to use too long a screw to hold the tray down to the cross bracesor you will have extra vents in the tanks!
You can see the new home for the pump in the "V"of the duct, this all movedthe CG back about 25mm.
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Old 08-02-2012, 01:52 AM
  #100
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Default RE: JET LEGEND VIPER BUILD THREAD

Where did you locate the UAT?
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