RCU Forums - View Single Post - JET LEGEND VIPER BUILD THREAD

10-03-2013, 08:04 AM

#837

Mark Vandervelden

Join Date: Jul 2012

Location: Bournmouth UNITED KINGDOM

Posts: 495

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Hi Guys

Thought I would post a few pics of my latest Viper build that was finished and flown a few weeks ago.This one was for a friend whom needed a home for his Booster 90 with which it went very well. Due to a change of direction and not a reflection on the airframe it is already now owed by another good friend of mine whom I retro fitted it with his Kingtech 80. This should also be a very good match giving very similar power for very little extra weight although as yet not "re-maidend".
Using my experiences with the other Vipers that ive built over the past year or so I have incorporated a few modifications that I found useful.
The first was to remove some of the base of the fin strake. I was then abel to run the elevator and rudder leads out through the fuz just behind the turbine hatch along the outside of the fuz well out of the way of the tail pipe. There has never been an issue with the leads inside but it cant hurt to be away from the heat and it allows for slightly shorter leads to be used as you can now use all of the servo lead with out having to tuck it back up into the fin.
The second it to face the top of the forward R/C deck with 2mm liteply, Then pack it up away from the centre deck with two 5x2mm liteply strips across the fuz glued to the underside at it rear were the two meet as a spacer. This lifts the front deck sufficiently to allow it to clear the nose wheel when retracted. This both tidy's up the battery tray area and closes off the fuz from any stray grass, debris or splashes from wet runways.
Third! I have made up a liteply plate were the air lines and aile,flap leads exit ether side of the Fuz . To these I have fixed the male half of the three JL air connectors and the two sockets of the Ex leads from the Rx. This allows you to simply slide the wing on to its tube and connect it all up with one hand in the restricted space left wile holding the wing with the other. This save asking or needing help as with most swept wings they tends to swivel round and drop there trailing edge during rigging.
Last is and has been mentioned many times before is to only use only one of the 1500cc tanks in front of the inlets, then use two smaller tanks ether side of the turbine. In this case I've use two 800cl tanks that I've managed to find. Many have used the nicely moulded 950cc tanks available as smoke tanks from JL. This is not an essential mod as the JL Viper is very tolerant of CG change but for very little work it both helps with any change in flight trim and gives a bit more room up front.
R/C install comprises of a Powerbox duel reg switch using two 2200ma lipos for power, a 12ch JR Rx. Turbine uses a 3200ma ecu lipo mounted at the front of the main tank and a std centre pickup 4oz air trap. I have mounted the ECU on top of the inlet duct and the pump below the front of the turbine with the fuel/kero valve ether side on the turbine rails. Mounting the ancillary's near the Turbine keeps the associated leads to a minimum. Servos used were std 6.4Kg digis all round using only long enough servo arms to give the appropriate movement at a minimum of 100% travel adjust. The only exception was on the elevator servo were a JR 8411 11kg was used but again with as short a servo arm as is practical to give the best mechanical advantage to the servo over the elevator. This same setup was used by myself in Vipers that have now flown for the best part of a year and worked well. No lead was needed to achieve the now accepted CG at 35mm back from centre of wing tube dry with gear up.

Last edited by Mark Vandervelden; 10-03-2013 at 09:13 AM.

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