Canopy.. Needs to have a small carbon pin installed in the from edge around the 12 oclock position to stop sideward flex when fitted to fuselage
I suggest that you fit the cockpits to the canopy tub as this makes operation much easier when you remove the canopy as all of the radio tray/ tanks is accessible with ease. Both my VJ2m's have arrived with the plastic canopy tubs fibre glassed from the factory. Long may this continue as this makes them far more durable, especially when you are resting the canopy/ cockpit tub combo on them frequently. If yours arrived not glassed then I suggest this mod is made
Fuel tank. Ideally it needs the hole for the bung to go through lowering so its nearer the middle of the tank, thus allowing the clunk more space to move around the tank while doing aeros. I also suggest the use of BVM poly tubing for a more flexible clunk set up
I would also suggest for those using P-80 size turbines that they fit a second tank. I am using a Dubro 40 Oz tank on top of the intakes and this added to the 2.3L standard tank gives me a happy 8 mins with a P-80 SE.
Gear doors.
The standard from factory set up works perfectly on the ground but blows open in the air. It needs the attachment points moving away from the hinge points for mechanical advantage. To do this means moving the cylinders away from the horizontal location in the bottom of the fuselage to a vertical.
Servo horns.
To get the desired amount of travel on the control surfaces quite long horns need to be fitted onto the servos to get the linkage up and away from the wing/ Stab and rudder surface.
Wing root
I suggest that a small square of 1/6th ply be fitted where the screw goes through to secure the wing. Without it it is very easy to over tighten this screw and crust the root rib on either wing or fuselage as there is a gap there.
On this subject... I do not use the normal suggested fixing of a screw through the fuselage into the captive nut pre installed into the wing root. Instead I screw a 4mm bolt into the captive nut so that it is permanently installed in the wing root. it then protrudes into the fuselage so I can simply reach in from the wheel well and bolt on a 4mm wing nut. I find this far easier than getting under the model with a 4mm bolt and allen key to do it up.
The gap between flap and aileron is very very tight. I found it necessary to sand/ bevel the edge of flap and aileron to allow more movement. Also I found as standard if the flap moved upward the slightest amount from its neutral point the two surfaces could bind. 5 mins with a file or scuff board took care of this.
My first VJ2m had quite some movement in the stabs when attached by the single factory fitted bolt from the underside. I drilled another 3mm bolt into the rear carbon spar. I then installed a balsa dowling into the tube so it could be tapped out ( Then thin CA'd to reinforce the thread) Thus eliminating any forward and aft movement in the stab set up. A bit belt and braces I know but I just dont like movement in a flying surface.
While at the back end. I suggest installing a balsa sheet between the tailpipe and the area where the servo wires go through the stab root and connect with the stab servos. The reason being that it would be all too easy to connect the stab servos to the extension leads inside the fuselage and push them into the fuselage to get them out the way. This would mean that they would come in contact with the tailpipe which is not a good idea. The balsa sheet acts as a barrier for the extensions to sit on away from tailpipe
On the subject of tailpipe...
My current 2m is running with zero nose weight, even with a P-80 Se installed. ( The first needed a fair few ounces of lead to balance) The reason being as follows..
On VJ2m number 1 I installed standard size JR 8411's in the stabs. I just felt safer this way as its my tried ands tested servo set up. On model number 2 I went with the suggested Midi size servo and fitted the JR DS3201. This is a plastic geared 4 KG of power digital midi servo. I know to some this will appear to be too small and under spec a servo, and I have to admit I was dubious. But to date I have had 4 flights with this servo set up and pushed the model as hard as I can with repetitive positive and negative snaps. Continuos rolling loops and cuban eights. Square loops, constant loops ( Both inside and outside) Tightening in diameter till the model eventually snapped out and some very aggressive and high speed pull to push manoeuvres at high speeds. Basically a flight envelope outside of what I would expect top see of a jet of this type, and have had no issues, flutter or even a feel of control surface response fading.
I am happy to recommend a midi servo set up, but fully understand why some may want to use smaller servos. To these end users I would say, it is possible to fit 8411 size servos. it does require some careful work sanding out the servo carrier rib in the stab and the surrounding area, just be aware you may need to add nose weight to counteract the extra weight of the larger servos so far aft in the model.
On the second model the turbine was also moved forward some ways compared top the first. I still have another 2-3 inches that I could go but the restricting factor is the tailpipe length. On this model I have moved the turbine as far forward as I dare ( I have 1.5 inches between tail cone of the P-80 to the inlet to the tailpipe ) and even then I have had to cut down the cosmetic bolt on tail come that bolts on to the outside of the fuselage by approximately 2 inches. This is not noticeable and was only a precautionary measure to stop the thin fibreglass from melting. I have also added a coat of heat shield paint to the inside of the remaining tail cone just to be safe. So far I have seen no distortion of this tail cone, but will be sure to update as time goes on if this changes.
I guess all of the above is just a heads up to say to owners that it is finally possible to get a nice scale jet without having to add nose weight, or huge batteries to balance. You just need to be aware that a bit of attention to the very back end of the model will pay dividends.
The ventral fins on both my models have come loose. I must say not in normal use but rather when I caught them loading them in the van. As when the model sits on its belly they are very low and easily knocked. Both times the same thing happened in that the 3mm threaded rod broke free from inside the ventral fin. What I do know is drill a 4mm hole through the inside skin of the ventral fin ( So it is not visible when they are fitted) I then pour rocked powder in and around the the thread of the rod inside the ventral and cyno to harden. You could use epoxy/ aeropoxy just be mindful of the weight added to the back end.
Some will argue that it is better that these fins are easily detached if knocked so will choose not to do this mod, which is fine as they have never come loose in the air.
Ref the finish of the model..
So far the only VJ2m's that I have seen or had experience of have been painted in the mould examples. The initial impression of these as they come out of the box has not been great. With both myself and customers commenting on the dull finish of the paint work, and appearances of quite a few surface blemishes and imperfections. This is one of the draw backs I guess of a paint in the mould finish. The good news is that it's not all as bad as it first appears. I have found that most of the imperfections seem to be removable, and the dull finish is also workable. Both my models have had a few hours spent by me in T cutting and polishing the top coat, which has in both cases transformed the appearance of the model. I found that I could remove many if not all of the finger prints or marks which seem to be in the release agent. Then a polish with a good car polish really helped bring the top coat to a good shine. I am sure many of those that have seen either of my vipers up close can testify to that?
I also found that a little bit of time spent on markings makes a world of difference. I have worked with a great vinyl guy here in the UK to make a complete sticker sheet that really helps transform the VJ2M. These include the following .
2x Viperjet 2m logos ( just no 2m for those with the larger ones )
2x Als Hobbies ( These will be free and for customer to use as they please )
2x Chrome fuel fill caps
2x Chrome Vents for rear under tail near tailpipe
2x Chrome circles with rivets for rear side of fuselage
2x Chrome without rivets ( same area as above)
8x Chrome vent holes for vents on the very front of the nose
2x Spektrum stickers
2x Jet Cat stickers
the above can be changed by request
200 Chrome rivets
40 smaller chrome rivets that will work for the rivets around the apu exhaust on rear side of fuselage and if you want to they also look good going down the side of the intakes.
As well as lots of lengths of 3mm black trim line that when applied to the line between yellow and white really makes that contrast stand out.
All in all I spend an entire evening on just the appearance of the model. Between the T cut, polish and sticker application. I really do think this is a worthwhile exercise as it transforms the model.
The equipment list of what I have used in the model is as follows.
Jet Cat P-80 Se
JR 8411 x 5. Ail. Flap and rudder JR super servo horns on flaps. After market longer horns on Rudder and ailerons to get throw ( These were one hole longer than JR horns)
JR 3201 x 2 Stab with JR super servo horns to get movement required.
Hitec 645 steering
Spektrum 12100 Power safe Receiver
Airpower EV5u multi valve and sequencer
I changed my door rams to BVM 3" stroke ( Mains only. nose is stock)
3300 Mah Jet Cat Lipo for ECU
2x 2500 AA size Nimh 6volt RX packs. All bats in the nose section either side of nose retract bearers.
Dubro 40 Oz tank as secondary Tank
UAT ( or equivalent)
BBI/ Dragon Pilot in front seat only .
We are currently working on a really professional set of wing bags for the 2M. They will be a smaller set of what we have already for the Big Viper jet and go along way to helping protect your pride and joy. I will update when these are available.
Sorry to waffle on, but these are things I have picked up from my experiences and I hope they may help new or possible VJ2M customers. If you have any questions then please feel free to email me directly on
[email protected]
I will try to follow up soon with some photos of various things on my 2M as well as an accurate centre of gravity and what control throws that I am using.
Regards,
Ali Machinchy, Al's Hobbies
Managing Director
www.alshobbies.com