madmodelman

It's obvious you don't care what I say but you come on this thread, ask a load of questions most of which have been covered, then suddenly have all the answers without even having one flight on a Viper.
I've now along with others clocked up well over 40 flights so I think I know how the thing flies a little better than you guessing how it flies.

essyou35

My Feedback: (11)

Oh ok,so apparently we have an airframe that has no drag and land at walking speed. Maybe BVM should study this model because it is the best one ever made!

IMO the wings are draggy. I dont how many time you fly it that doesnt mean you know if the wings are draggy or not.. Oh you must be one those "jet pilots" who works for NASA and has a wind tunnel.

The thickness alone will tell you its not that clean of an airframe. I dont care its a cheap everyday flyer for me and has a wide flying venue.

And I dont think I have all the answers, I just think the wings are draggy get over it. I also think the tank mod is a great idea.

Not sure whats up yours lately.

essyou35

My Feedback: (11)

Decided I would come back and quantify my thoughts on why I think the way I do.

Attached are some pics comparing the wing of my 1/8 f-16 to the wing of the Viper jet.
Both jets use turbines with basically the same thrust (k100 and JC rabbit), the rabbit having slightly more thrust.

Both jets are similar in weight.

However, the viper is larger, by quite a bit. Larger airframe = more drag. More wing area=more drag. Thicker air foils on wings and tail = more drag.
The f-16 had gear doors. the viper does not.
The f-16 has a smaller intake area than the vipers two intakes.

YOu can see from the pics what I am talking about.

So with that said, while I do not know exactly how the viper will fly. I do know very well how my f-16 flies. As proven above, and by the pics, the JL viper is just as draggy, if not more draggy, than the f-16 given the things I mention above.

I know there are some airframe differences here (duh) but the viper is not setup to be a performance jet with the types of airfoils used. Look how thin the wings are on the f-16.

I do not expect the viper to out perform the f-16. therefore, I expect it to perform less, and therefor I can deduce how it flies in terms of speed and climbout.

With a k100 it will fly but not be a rocket, similar to the f-16. Both jets could use a P120 for sure. I would not trust the f-16 airframe though to withstand the G forces from that speed.

It is not my goal to argue nor pretend to know everything. I will fly my jet soon and from past experiences my thoughts have been right on with other jets. This is not going to be a high performance setup, but a great everyday flyer! I make my opinions based on facts (or what I think are facts), not just make it up out of thin air, I hope you can see that. That doesnt mean I am always right either.

Really looking forward to it.

Jeremy_D

I think you will be pleasantly surprised by the speed of the viper. I can get what I would say is near unlimited vertical at full throttle with my P80se. Even to slow it down I need a circuit and a half at 3/4 to drop the speed before I deploy my first stage of flap to setup for landing. My maiden flight I had to land with no flap due to my elevator mix being incorrect and it took me 3 attempts to land it, trust me it is slicker than it looks but will slow to a walking pace with the right flap / crow setup I actually think your viper will be quicker than your F16, no dirty big intake underneath either way I know you will love it!

essyou35

My Feedback: (11)

Jeremy of course I will like it, I didnt mean to imply I wouldnt. I jsut mean to imply I dont expect it fly like a bandit with a p120 in it.

I accounted for the intakes, being underneath done matter, its the area of the intakes, and the viper has more area. Probably to allow larger turbines.

I just hope you can understand my thoughts with the thick wings, it is not as "Clean" as it could be. but we get what sounds like a great landing speed!

mikedenilin

My Feedback: (67)

I am flying one with 24 lbs of thrust. It can fly close to the speed of bandit or faster. I normally fly at 50-60% throttle. Even though it has more profit than the F16, but it's more laminar airfoil and does not bleed off speed in turns.

In our local airfield, we have people flying this Viper with

T-12, MVT-80, and M-100. They are all flying fine. The one with VT-80 flies great, but not a rocket. However it's fast. When I saw it flies, it was doing at about 160-180 in a small Hemet field that takes 3-4 seconds to turn constantly in a lap. I will talk to the VT-80 pilot and see what his settings are.

Scott is flying it with a M-100 and he can tell us how he flies.

My is T-12. Same as William (in China) viper's engine. It's a big engine and fly it like a rocket. The plane is too clean and I need to max out the flaps so I can slow it down. Anyway I think this Viper flies best with 80-100 size turbine. Rabbit will give it an extra kick but won't be too massive. Of course anyone wants a rocket, then a p120 will be over the top.

Mike

essyou35

My Feedback: (11)

Mike when we go to Kentucky Jets, Lets make sure we tell people the viper is faster than a Bandit given the same motor.

People will want to know this! How are you measuring speed?

Ill report back once I fly, if I am wrong. At this point I have some high expectations and Ill just say I am wrong wrong.

So to correct myself, the JL viper is one of the cleanest airframes ever made, It also outperforms BVM and cost less than 1/3 of BVM! I cant wait to show up at my field and tell everyone this. Then I am going to fly it and crap mu pants.

I sincerely apologize for my inaccurate speculations.

2 servos to go and I can fly! Now I am really stoked.

A4Driver45

My Feedback: (7)

Greetings from FL. hey guys, I have been reading the in put of speed and landing speed, I have a rabbit in mine and beleive me it is as fast as I want and yesterday was the first full flap landing, I was very surprised how slow it got without any ugly things going on.... I don't know too much about airplanes, I'm an old Navy driver with about 3000+ hours of full scale aircraft, jets to the two engines type airplanes..... the Viper is a great flying airplane, I may be wrong but the Viper was built for us guys that want a good looking airplane and if you want to go fast spend 4-5 k and put in a 120, 180 or a big Jet Central and go fast....I hate to see the back and forth BS, lets keep the build site for what it was ment to be to help to put the viper in the air

Rocky Kranz

essyou35

My Feedback: (11)

Hi Rock,


I have yet to hear one person say they dont like it at all. Havent heard of one coming apart, no complaints at all. I'm not trying to dog anything just calling it as is. I usually get into some discussion about speed on these things. Seem some guys think if they pretend thier jet is the fastest ever, somehow the girls will come running
I expect 130-140 cruise and 150-160 top speed with my turbine straight and level, plenty fast for me. I dont plan to beat it up in dives nothing to prove. I have 3 kids and a stay at home wife, I was born dirt poor so I dont care and I buy cheap jets but I wont pretend I have a BVM bandit either. The canopy alone is a huge source of drag.

ceffi

Hello,
I checked the speed with a Graupner GPS of my Viper several times with the JetsMunt Merlin 100 two weekends ago.
Nearly 140 kts without any wind and straight and level.

Christian

essyou35

My Feedback: (11)

140 kts = 160mph? Sounds very reasonable thank you ceffi. Speed is highly subjective, but given the thick wings its about what I would expect. I may actually have less speed than that due to my altitude. I'll measure mine with my GPS module when it gets here, I ordered the same one.

A4Driver45

My Feedback: (7)

Greetings once again, hey guys thanks for the help, I believe it's time for me to get out of the build, I so far love the Viper for the cost it's a great airplane, I hope everyone has the same fun with your Viper as I plan on having with mine, it's too bad that the build has to get into my dog is bigger and can dump more than yours, I don't care how fast or how high the Viper or any other airplane can go....it stops being fun with this going on....every one stay safe and again thank you for the help.

Rocky Kranz

essyou35

My Feedback: (11)

You can stay man I'm out. I'll post a few pics of my mods and be done. Not going to argue about trivial crap. I made a comment, showed my evidence of it and still get bashed.

Bob_B

My Feedback: (11)

Si youre coming to JOK cool!

roystonflyer

Hi Guys

My viperjet is ready to fly. Just need to set up the control throws.

What are people using?

Cheers

roystonflyer

Hi

How did you wire the smoke pump. Mine has 2 plugs, 1 with a white wire, the other with the black and red. Which ever way i wire it, trying to use use a seperate battery it doesnt work.
Any ideas would be rewally helpful
Cheers

essyou35

My Feedback: (11)

Here are a couple docs that Mike Lin sent me, not sure if there are available somewhere or not. Deals with throws and CG

Jeremy_D

Those throws are perfect and are taken off my viper setup.

roystonflyer

Thanks for those, thathelps alot. Had to removethe smoke pump tonight ascant get it to work unless i conect both plugs together on a y lead into the rx. Dont really fancy running the pump through the rx.

essyou35

My Feedback: (11)

Not alot to complain about on this jet but I must say the front gear steering setup leaves a lot to be desired.

Jeremy_D

Use a single arm setup, I had to remove a little bit of the cut out to get mine to clear upon retraction. I'll take a pic of mine if you like when I get home tonight to show you my setup

roystonflyer

The smoke pump is a jet legends one, as is the turbine, if that helps

Jeremy_D

Hi Essyou,

As promised here are the pics of my nose wheel servo setup. Make sure you file flats on the nose pin.

The way I got the servo on was to take off the nose strut and steering arm and then unscrew the plate.

ceffi

hello,

the same by me.
I also didn`t get the smoke pump working.
Now I use an old fuel pump with a old ESC for brush motors.

Christian

essyou35

My Feedback: (11)

Jeremy, as you can see in your pics you also had to sand away part sof the fuse to get it clear. I also had to sand into the formers to get it to clear down below. Due to the servo I chose I cannot use a short arm like that, the ball link hits the servo.

So I had to install the servo upside down, so when my gear is in the down position, the servo sticks out the bottom of the fuse. It seems to work though I have a bad geometry with the linkage. Hoping the position of the servo doesnt act like some sort of counterweight and make the gear not want to work. I will test the retracts today.

I'll test it good but regardless the nose gear setup leaves a lot to be desired.

I have the Red HPAT version is there supposed to be decals that say "viper jet" for the wing and the tail? I didnt find any decals in my kit.