JET LEGEND VIPER BUILD THREAD
06-09-2013, 08:37 AM
#726
My Feedback: (67)
RE: JET LEGEND VIPER BUILD THREAD
Guys, another question...
For those that have taken there vipers up high and stalled them, does it just drop it's nose, or does it drop a wing? I have taken mine up 3 or 4 times and all those times it dropped it's wing pretty severe, however I did recover fairly quick. I was under the impression from a post by Mike from GJC that the wings have a 1.5 deg. washout. When I measured mine, they do not have this washout in them. They are straight. Even on landing, if I bring it in and bleed a bit too much speed off, it drops it's wing pretty bad. My cg setup is 35mm behind center of wing tube like others. Weight is 22lbs. Throws are what others are using, if not just a bit less on elevator.
Also on take off when full load of fuel, it wants to snap on me. I measured the incidence when sitting on the ground and it is at -1 deg. This requires a tad too much elevator to get it to rotate. I am using mid flap position to take off which helps. I am going to try and raise the nose gear about a 1/4 of an inch which will give a slight positive incidence which I believe will help in rotation. This was the case with the Falcon 120 and an F-16 I use to own.
I have also considered re-flexing my ailerons down on both sides a mm or two to help add washout into the wing. However, this does not help on landing when flaps are deployed.
For those that have taken there vipers up high and stalled them, does it just drop it's nose, or does it drop a wing? I have taken mine up 3 or 4 times and all those times it dropped it's wing pretty severe, however I did recover fairly quick. I was under the impression from a post by Mike from GJC that the wings have a 1.5 deg. washout. When I measured mine, they do not have this washout in them. They are straight. Even on landing, if I bring it in and bleed a bit too much speed off, it drops it's wing pretty bad. My cg setup is 35mm behind center of wing tube like others. Weight is 22lbs. Throws are what others are using, if not just a bit less on elevator.
Also on take off when full load of fuel, it wants to snap on me. I measured the incidence when sitting on the ground and it is at -1 deg. This requires a tad too much elevator to get it to rotate. I am using mid flap position to take off which helps. I am going to try and raise the nose gear about a 1/4 of an inch which will give a slight positive incidence which I believe will help in rotation. This was the case with the Falcon 120 and an F-16 I use to own.
I have also considered re-flexing my ailerons down on both sides a mm or two to help add washout into the wing. However, this does not help on landing when flaps are deployed.
06-09-2013, 10:22 AM
#727
RE: JET LEGEND VIPER BUILD THREAD
I'm pretty sure you would want to reflex your ailerons up to provide washout, not down.....I have stalled mine at altitude as well and noticed it drops a wing pretty aggressively, but I don't have the snapping tendency on take off. My cg and throws set as per the recommendations given in this thread.
06-10-2013, 10:36 AM
#730
My Feedback: (11)
RE: JET LEGEND VIPER BUILD THREAD
Hi Noahb,
Yes, the viper will snap or tip stall. I mentioned this before not to complain but to inform. I too snapped on takeoff once. Your problem may be that your CG is too far forward. If you are using the stock tanks without any smoke fuel you will be way too nose heavy and will need long run out. On grass with my CG at the recommended position with tanks full, it takes me about 400 feet to get off the ground. If you doing that or less with both front tanks full you arent letting it get enough speed.
Using crow will help a lot, but keep in mind it requires power on during landing as the crow will act like a speed break. I would not put the ailerons down, you will make the tip stalling worse.
The viper is an easy flyer but it is not quite a trainer as it does snap, and cant land at stall speed like some of the true trainer type jets. It will still rollout 2-300 feet without brakes, meaning there is still plenty of speed on landing.
Let us know your tank configuration. Also is your front nose gear completely depressed when full of fuel. Some early ones (and mine) had this issue, needed to add oil and air.
BTW I weighed my viper and I am 27.5 lbs wet.
Yes, the viper will snap or tip stall. I mentioned this before not to complain but to inform. I too snapped on takeoff once. Your problem may be that your CG is too far forward. If you are using the stock tanks without any smoke fuel you will be way too nose heavy and will need long run out. On grass with my CG at the recommended position with tanks full, it takes me about 400 feet to get off the ground. If you doing that or less with both front tanks full you arent letting it get enough speed.
Using crow will help a lot, but keep in mind it requires power on during landing as the crow will act like a speed break. I would not put the ailerons down, you will make the tip stalling worse.
The viper is an easy flyer but it is not quite a trainer as it does snap, and cant land at stall speed like some of the true trainer type jets. It will still rollout 2-300 feet without brakes, meaning there is still plenty of speed on landing.
Let us know your tank configuration. Also is your front nose gear completely depressed when full of fuel. Some early ones (and mine) had this issue, needed to add oil and air.
BTW I weighed my viper and I am 27.5 lbs wet.
ORIGINAL: noahb
Guys, another question...
For those that have taken there vipers up high and stalled them, does it just drop it's nose, or does it drop a wing? I have taken mine up 3 or 4 times and all those times it dropped it's wing pretty severe, however I did recover fairly quick. I was under the impression from a post by Mike from GJC that the wings have a 1.5 deg. washout. When I measured mine, they do not have this washout in them. They are straight. Even on landing, if I bring it in and bleed a bit too much speed off, it drops it's wing pretty bad. My cg setup is 35mm behind center of wing tube like others. Weight is 22lbs. Throws are what others are using, if not just a bit less on elevator.
Also on take off when full load of fuel, it wants to snap on me. I measured the incidence when sitting on the ground and it is at -1 deg. This requires a tad too much elevator to get it to rotate. I am using mid flap position to take off which helps. I am going to try and raise the nose gear about a 1/4 of an inch which will give a slight positive incidence which I believe will help in rotation. This was the case with the Falcon 120 and an F-16 I use to own.
I have also considered re-flexing my ailerons down on both sides a mm or two to help add washout into the wing. However, this does not help on landing when flaps are deployed.
Guys, another question...
For those that have taken there vipers up high and stalled them, does it just drop it's nose, or does it drop a wing? I have taken mine up 3 or 4 times and all those times it dropped it's wing pretty severe, however I did recover fairly quick. I was under the impression from a post by Mike from GJC that the wings have a 1.5 deg. washout. When I measured mine, they do not have this washout in them. They are straight. Even on landing, if I bring it in and bleed a bit too much speed off, it drops it's wing pretty bad. My cg setup is 35mm behind center of wing tube like others. Weight is 22lbs. Throws are what others are using, if not just a bit less on elevator.
Also on take off when full load of fuel, it wants to snap on me. I measured the incidence when sitting on the ground and it is at -1 deg. This requires a tad too much elevator to get it to rotate. I am using mid flap position to take off which helps. I am going to try and raise the nose gear about a 1/4 of an inch which will give a slight positive incidence which I believe will help in rotation. This was the case with the Falcon 120 and an F-16 I use to own.
I have also considered re-flexing my ailerons down on both sides a mm or two to help add washout into the wing. However, this does not help on landing when flaps are deployed.
06-10-2013, 10:50 AM
#731
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RE: JET LEGEND VIPER BUILD THREAD
HI I am using two programmable mixers one for each aileron to get crow,my radio is a futaba 12z, in the mixing if you use a line there are 7 points that you can set for the up aileron or crow,this means that you can use a very small amount on take off with half flap and get more crow with full flap,the amount of up aileron can be as much or as little as you like and is progressive with the flap regards Keith
06-10-2013, 03:57 PM
#732
My Feedback: (67)
RE: JET LEGEND VIPER BUILD THREAD
essyou35,
I run the two smoke tanks and one of the 1500ml tanks like some do. My CG is set at 35mm behind center of wing tube. I did two things to the nose gear, one I put a spacer to put a tad more tension on the main spring. Second I put a tube inside the strut so that it would not collapse all the way down. My "scissor" on the front strut was very close to hitting the ground if I hit the brakes hard.
I run my mains with a bit more air than most. When full of fuel, they compress maybe a quarter of there travel. However, for those that have the abrupt take off, check your incidence when sitting level (like you would be on a runway). Mine had nearly -2deg in the wings. This plants it down on the runway forcing you to use a bit more elevator than is required. When it does rotate, it can quickly induce a stall. I think essyou35 found this out on one of his take offs. I am in the process of lengthening my nose strut to give me about 1/2 to 1 deg of positive incidence. This will allow a much easier rotation. My buddy's skymaster viper when level has +2 deg of incidence.
Outside of that, it's a nice flying jet and I look forward to getting more time on mine. If I ran less air in the mains (where they would nearly collapse all the way) the incidence is about -1/2 with stock configuration.
Larry
I run the two smoke tanks and one of the 1500ml tanks like some do. My CG is set at 35mm behind center of wing tube. I did two things to the nose gear, one I put a spacer to put a tad more tension on the main spring. Second I put a tube inside the strut so that it would not collapse all the way down. My "scissor" on the front strut was very close to hitting the ground if I hit the brakes hard.
I run my mains with a bit more air than most. When full of fuel, they compress maybe a quarter of there travel. However, for those that have the abrupt take off, check your incidence when sitting level (like you would be on a runway). Mine had nearly -2deg in the wings. This plants it down on the runway forcing you to use a bit more elevator than is required. When it does rotate, it can quickly induce a stall. I think essyou35 found this out on one of his take offs. I am in the process of lengthening my nose strut to give me about 1/2 to 1 deg of positive incidence. This will allow a much easier rotation. My buddy's skymaster viper when level has +2 deg of incidence.
Outside of that, it's a nice flying jet and I look forward to getting more time on mine. If I ran less air in the mains (where they would nearly collapse all the way) the incidence is about -1/2 with stock configuration.
Larry
06-12-2013, 02:24 AM
#733
RE: JET LEGEND VIPER BUILD THREAD
One thing that I really like about this jet is the clear NAV/Strobe light covers on the wing tips. I know that some people have put their own lights in, either homemade or commercial. I saw some little LED micro torches for sale in my local auto supply shop for $2.95 each, complete with button batteries! Each one has three 1.5v batteries and when measured by multimeter, I was showing 4.4v. I cut most of the body off and soldered some connecting cables, and then connected them up to a 1s LiPo battery.They are incredibly bright and extremely light, but the really good thing is that they are a perfect fit in the wingtip light housings. I will run them off a RC switch and a separate 1S battery. Also, here is the pilot figure that I have mounted in cockpit. He is correct scale, and I am now making up a control column and a seat harness. I personally feel that a model jet requires a pilot figure, just doesn't look right without one!
06-12-2013, 12:38 PM
#735
RE: JET LEGEND VIPER BUILD THREAD
ORIGINAL: jetmodeller
Hi Where did you get your pilot figure? regards Keith
Hi Where did you get your pilot figure? regards Keith
06-13-2013, 06:08 AM
#737
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RE: JET LEGEND VIPER BUILD THREAD
Hi,
I think buy servo Savox SC-1267SG for all controls with power 7.4V.
Weight(g): 62.0
Speed(@7.4V sec/60): .09
Torque(@7.4V oz-in): 277.7
Gear: Unique Steel
Bearing: 2BB
Case: Aluminum
Someone with a return of experience? reliability for Jet?
I think buy servo Savox SC-1267SG for all controls with power 7.4V.
Weight(g): 62.0
Speed(@7.4V sec/60): .09
Torque(@7.4V oz-in): 277.7
Gear: Unique Steel
Bearing: 2BB
Case: Aluminum
Someone with a return of experience? reliability for Jet?
06-15-2013, 02:39 PM
#739
RE: JET LEGEND VIPER BUILD THREAD
Guys, here are some more pics on my version of landing lights and cockpit detail. Very basic, but I think that it sets the jet off abit.
06-15-2013, 03:05 PM
#741
RE: JET LEGEND VIPER BUILD THREAD
Thanks Jeremy, I really enjoy making something from stuff that I have lying around. I was especially pleased with the lights, as the total cost was under $10. I made the RC switch too, using a tiny 6v relay and a small brushed speed controller.
06-16-2013, 10:00 AM
#742
My Feedback: (67)
RE: JET LEGEND VIPER BUILD THREAD
Here are some pics of mine next to a skymaster 2M viper. Outside of the scale details (lack of on the JL Viper) the biggest difference is the fuse size on the SM viper is noticeably larger (bigger around). They fly pretty similar, with the skymater being just a tad bit smoother in flight, but very close. Also a picture of my install in the front.
I did raise the front strut to give a positive incidence, this was a night and day difference on takeoff. Now, I just barely pull a bit of elevator and she rotates very smooth. Before I had to pull a bit of elevator and then she would jump off.
I did raise the front strut to give a positive incidence, this was a night and day difference on takeoff. Now, I just barely pull a bit of elevator and she rotates very smooth. Before I had to pull a bit of elevator and then she would jump off.
06-16-2013, 12:29 PM
#745
My Feedback: (67)
RE: JET LEGEND VIPER BUILD THREAD
Yep, the jet legend is not very scale. The skymaster is much more scale. However, mine weighs about 22.5 lbs, the skymaster with a cheetah weighs about 27 lbs, both dry.
I am also running a different set of wheels and brakes. The new air fill tires are not very good IMHO. I wish they still had the solid tires on these.
I will be installing smoke sometime in the near future. Just need to decide where to put the smoke tank and then go from there.
I am also running a different set of wheels and brakes. The new air fill tires are not very good IMHO. I wish they still had the solid tires on these.
I will be installing smoke sometime in the near future. Just need to decide where to put the smoke tank and then go from there.
06-16-2013, 12:46 PM
#746
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RE: JET LEGEND VIPER BUILD THREAD
Larry, are you going to start a thread on how to install the smoke system? I have read different and mixed reviews on where the tube should be placed either behind the turbine or at the exit of the pipe and this would be with the smoke tube running threw the pipe for preheating the oil.
06-17-2013, 02:54 AM
#748
RE: JET LEGEND VIPER BUILD THREAD
Hi Noahb, Is? that orange Viper in the pic the Skymaster M at 85" or the S at 68". Its the first time I've seen the two different makes next to one and other and its deceiving. I thought the M version was much bigger and would be disappointed if it is, especially at that weight and is well over a $1,500 more than the JL version. If perhaps its the "S" version at only a little over a $1,000 more I would have to re-considered it as a EDF project as in the pic as it now looks a bit big for the setup I had in mind, plus I've just noticed it only has std oleos. I could swap out the UC legs for trailing links on ether SM version by using the ones from JL version to fly from grass more easily. I've had JL Vipers on and off for some time now and consider them "sports scale" and with out being picky a very good representation of a Viper but that is completely out weighed by the fact they make a really good sports jet.
06-17-2013, 06:37 AM
#750
RE: JET LEGEND VIPER BUILD THREAD
Hi LF, Thanks for confirming that, Lovely colour and like it a lot, I would imagine it shows up well. I don't think Orange is an option yet with JL but if you ask nicely you can have them in any colour. Here in the UK anything that shows up against a grey background works well :-)