S3 Viking Jet Design

Apr 20, 2011 4 Comments by

I originally designed, built and flew my EDF Viking in 2005 having all intentions that, if it  performed well, to publish the design in Model Airplane News, as I had with a number of my earlier designs. It flew quite well so I decided to tweak it a bit, clean up and finalize the plan and move on. As we all know, electric power has made incredible progress in a very short time. Batteries, motors, and ESC’s have all improved dramatically providing reliable, powerful and affordable propulsion systems. I decided that modelers may like the S-3 but have no experience with EDF power systems, so I decided to try adapting the airframe to take conventional propeller systems. This arrangement far exceeded my expectations, performance-wise. A prototype was built by my friend Gene Davis and it worked like a charm.             Stay tuned!

 

Specifications:

  • Wingspan:                    60”
  • Wing Area:                   507 sq,in. (3.52 sq.ft.)
  • Length:             48.28”
  • Power:                         2 WeMoTec “Mini” (70mm) EDF units or propped outrunners
  • EDF Motors:                Hacker B40 7L
  • Channels:                      4 (5 w/retracts, 6 w/retracts and flaps)
  • Weight: (RTF)              6 ½- 7 ¼  pounds ( 104-116 oz.)
  • Wing Loading:  31 oz/sq.ft. (@ 7 pounds)

Rich Uravitch

About the author

His modeling career encompasses a broad range of aviation subjects, from small electric models and electric ducted fans to the giant scale and warbirds. He has been the Top Gun craftsmanship judge for several years. He has designed, built and flown several sport-scale RC aircraft, several of which can be purchased at the AirAgeStore.com website.

4 Responses to “S3 Viking Jet Design”

  1. Gene Davis says:

    The S3 Viking prop version as it is now has:
    Motor: Turnigy 35-48B 900kv x2
    Battery: Turnigy 5Ahr 4s one only
    8 x 8 APC electroc props
    each motor is about 450 watts. 30Amps.
    @ 11K rpm. on full charge.
    Performance is very good.
    Originally I had Rimfire 35-48 1600 motors
    using 3 blade 8 x 6 at about 45 Amps. each and
    two 3s 4Ahr batterys.
    Performance was ok but is much better now.
    The 6 inch pitch props were not enough pitch for the speed needed for good performance.. The two blade 8 inch pitch
    works much better and using only one 4s instead of two 3s batterys saves about a pound and improves performance..

  2. Bill says:

    Any more details on the availability of an EDF version? Would really, really like one of these. Flew the Viking from 92-07 and have fond memories of it.

  3. Gene Davis says:

    Up Date:
    After having one of my original EDF units explode, I had purchased and installed two units with reinforced fan blades from Hobby King. I had been flying the S-3 with propellers which performed very well. I just reinstalled my EDF wing (with flaps too). I used one new 5KmA battery instead of two 4KmA batteries that I had on the original EDF model… A great weight savings. What a difference a good new battery with good EDF units do..The EDF units pull 45Amps each on take off power and about 38 Amps on half stick.
    Gets me five minutes of flight time safely. Great performer now on EDF. Total power on take off is about 1000 watts.
    Regards.

  4. Gene Davis says:

    Up Date the Up Date.
    I wasn’t to clear on this. The 5kmAh Turnigy battery is a 3s with 25-35 discharge rating. The motors are Ammo 28-45-3600. The EDF units are HKEDF70 using Welgard 65 Amp controllers with fin cooling installed by me. Cooling fins are exposed externally on the bottom of the plane. Plenty of cooling here. Same controllers used on prop version too.
    The flat plate (not adequate) cooling sync was removed from the controller and a finned type heat sync glued on using “Artic Alumina Thermal Adhesive”. This adhesive is made for this type appication.
    Regards

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