Jason R.

Looks great good luck with the maiden.

Jason

javier161

Hello, I have a few questions regarding my Jetlegend viper, maybe you guys could help me.

1) My CG is more or less 35mm from the wing tube, but plane still needs considerably amount of down elevator when flying inverted,How your vipers fly inverted?
2) Guys using Igyro e3 how much gain are you using, yesterday I was in +43 and -40, but in hold mode, when inverted, plane still drops nose.
3)What are Heading hold used for, if rudder does not keep hold with the e3

Thanks.

M3Baker

Javier
I can only answer your first question as I use a Cortex gyro. The Viper Jet has a huge CG range. Very forgiving when nose heavy, very hard jet to fly when tail heavy. The fuel tanks sit forward of CG when using stock set up so you will always be a little nose heavy early on in your flight. Yes, it takes a little push on the elevator to maintain level flight when inverted on my jet. Lots of people use the smoke tanks as fuel tanks and reduce to just one center tank. This set up will improve the CG during flight. I'm very happy with the stock set up on mine though.
Hope you are enjoying your viper.
Paul

extra300s

Hi there

I also can confirm my jet with only the two stock tanks upfront required a ton of up elevator stick to keep level. Did not enjoy this one bit. It also had a nasty tendancy to snap from pulling to hard on the elevator out of dives. My next Viper I will use the smoke tanks as fuel tanks with a single 40oz dubro upfront as the main tank. This will result in a better cg (as confirmed by Mark and many other pilot on here), and also improve the flying capabilities like less elev when inverted. and hopefully a bit more forgiving plane with regards to high speed snaps. Will also build this one without a power box and keep everyhing a simple and light as possible to further improve the wingloading.

Will report back also once I have flown it.
Enjoy.
Karl

essyou35

My Feedback: (11)

Got my K140G installed. I made new mount rails for it in case I want to convert back to a k100g. K100g requires rails to be modified to fit as they are too wide, K140g requires them to be widened.

I really screwed up my front retract. I had made my own flex plates from hobby king carbon fiber. They were slightly thicker but a lot stronger. On my last landing, I landed in some grass that was very wet and the gear sunk in. So they ripped out but did a lot of damage to the mounting wood as the flex plates were too strong. The front retract pin bent quite a bit and I did more damage trying to straighten it. It seems to be ok but the front strut will not be perfectly straight up and down nor left to right.

I'll post some pics but I think the k140g will wake it up a bit, but I don't plan to fly any faster at all, just stronger climb out. It will also be nice for go arounds. I've flown in quite a few small places for demos and the lack of power on go around has made me stick some landings I would rather not of.

I made some new flex plates and them time will cut a "break line" with a cutoff wheel to ensure a good clean break next time. I would of thought hobby king CF would be weaker, go figure.

I wouldn't mind buying some spare parts for the gear but for some reason GJC doesn't stock anything, so a $12 pin has a $30 EMS shipping overhead. Be nice if they would stock some parts in the US given how popular these jets are.

Jim Cattanach

Unknown to me, a fellow flyer made a short clip of one of my Viper jet flights yesterday.
I am really pleased with this jet.
Now had about 20 flights.
I think he thought it was a Red arrows Hawk judging by the video title he posted.

https://www.youtube.com/watch?v=dPpC8UJK2U8

essyou35

My Feedback: (11)

Nice flight, do you run a gyro or anything? Looked really stable in the cross wind.

Jim Cattanach

No gyro. Just standard as it came from JL, with servos fitted. Just had to fit Batteries, Rx & turbine. I did away with the JL brake valve & fitted a Jet tronics valve, so I could program it to work on down elevator. I probably could have got the JL valve to do the job, but got fed up trying after an hour or so.
CG is 35mm from the rear of the wing tube.I have as much landing flap as I could get, around 80 degrees & about 5mm of crow on the ailerons.
The turbine is a Merlin VT80. For a six minute flight, it uses about 1.5 litres of fuel.

javier161

Thank you all for your kind advice.

Here is a link of some low passes from the weekend.

https://www.youtube.com/watch?v=Z6Sf...EpxwgMl7-D06_g

M3Baker

Hey essyou,
Hope you are doing well. I'm still trying to get use to this cold Kansas weather. I had a bent pin on my Viper too so I ordered a pin from Dreamworks and ground it down so it would fit. I put the pin in my drill and wrapped sand paper around it and held the paper tight while I ran the drill. Worked just fine. I think I had to cut it down a little as it was too long.
Take care!
Paul

essyou35

My Feedback: (11)

Thanks Paul,

Which pin did you get, can you post a link? Its getting the bent pin out that is a pain, however if I had a spare I could cut it out. Make it much easier.

Its cold today up here. It makes it working on jets hard as it appears there is no end in sight.

M3Baker

I'll check when I get home tonight. Maybe Jose will see this and chime in. I'm sure he knows the closest size available from DW. It will come right out after you cut it off.

rcjets12

My Feedback: (21)

Hi,

I remeber doing this on Paul's Viper and we just got a 1/4 pin from DW and we had to work it down to fit. It was a pain to do but we were able to get it done. I know we don't stock these pins and I wish we would. As for shipping from the factories I know it's pricy but that's what they charge to ship anything international these days. I remeber that we took the pin and put it on a drill with sand paper to work it down to what we needed. You will need some time and patience to do this way. I remeber telling Paul if it was not because we needed the jet fixed for an event I would have just paid for the shipping as it took us a while to get it done this way.

essyou35

My Feedback: (11)

Im going to talk to my machinist buddy about turning some down for me, shouldn't take more than a few minutes. Maybe we'll start selling these.

AlW

My Feedback: (17)

I am using a slider switch on a JR12X transmitter and in the ''off '' position the system will sit for a long time at 100psi. As you start to apply the brakes the valve has a clicking sound and looses air very quicky. The clicking speeds up as you apply more pressure. Is this a ''travel adjust'' issue on this channel? Thanks, Al

mikedenilin

My Feedback: (67)

Hi Essyou35,

We do have the key Viper jet spare parts in stock. we have enough Flex plates for 20 Viper jets and enough tires for 20 Viper jets as well. We just didn't have enough request for nose gear pin, but we do have spare nose gear in stock. The flex plate are designed to break before you can bend the nose gear pin. If you use the genuine JL parts, then you won't have to replace the pin. We also have spare valves, so far haven't received demand for these replacement parts either. I think this viper jet is the most reliable jet in our inventory. If you order the flex plates, and tires from us, I think the shipping cost would be just around $5-7.

Mike

Jon Mead

Looking at photos from earlier in the thread, it looks like JL have recently started supplying a larger air tank that won't fit transversely under the inlet ducting. The only location that I can find for the larger tank is vertically behind the tanks in the vee where the inlet ducts come together, or possibly on top of the inlet ducts. Has anyone with a large tank managed to find a location where the tank doesn't interfere with the rest of the install?

essyou35

My Feedback: (11)

Actually I was mistaken, the front flex plate is the stock plate. I made my own mains. the front flex plate that came with my jet still bends the pin. Sorry.

Do you plan to get a shipment of the pins in?

gsmarino2000

My Feedback: (2)

I just received my VJ two weeks ago and the air tank is installed transverse under the ducts. BTW this is the tightest pneumatic system I've seen. It will hold air for weeks at least.

Greg

mr shiners

Just started with the build on mine now

gsmarino2000

My Feedback: (2)

I've just finished my build and I'm attempting to balance the plane. I'm at 24lbs dry (except for fuel in UAT). I'm still tail heavy with the batteries all the way up against the nose bulkhead. My set up is K100G with the three tank set up, pump beside the front tank, UAT in the stock position and 1.25 lbs of LiFe batteries against the nose bulkhead.

The Viperjets originally came with ballast in the nose, but the recent versions don't. For those with the recent versions, what are you doing to balance the plane? With 7.5 lbs of fuel this plane will have a take of weight of 31lbs/14kg. I fly at 5200ft /1600m so wing loading becomes more of a concern. The only thing I can think of without adding dead weight is to move the pump up with the batteries. I prefer to keep the pump near the engine, but I suppose I could move it up with the batteries.

Thanks,
Greg

Jim Cattanach

Have you moved the CG back to the setting others are using?
If your UAT is forward, fill it with fuel for CG setting.

gsmarino2000

My Feedback: (2)

Jim,

I am going for 35 mm behind the wing tube center. UAT full, gear up, all other tanks empty.

Thanks,
Greg

Jim Cattanach

Greg. That is the same for me. Only thing different was, I balanced with the gear down. Not much else you can do, except fit bigger batteries, or add some weight in the nose. I did not need any extra weight, probably as my turbine would be a little lighter than yours.
I have as much flap on mine as possible, almost at right angles & about 5mm of crow. It seems to need the drag to slow down enough, even with the light Merlin VT80 turbine & I am at sea level.
Have a good maiden flight.
Jim

mikedenilin

My Feedback: (67)

HI Greg, I just put 2 pilot figures in the cockpit (Ken and Barbie). Mike