Henke Torphammar

Taft Hobby just came out with a new EPO Viperjet for 90mm EDF. Its also a perfect turbine convertion with alot of room for fuel and accessories. I know Ready2fly are already distributing this bird and I assume you will see it at your local hobby shop soon.

Wingspan: 1450mm
Length: 1274 mm
Motor: 1450Kv borstlös motor (PNF)
Controller: Hobbywing 80A (PNF)
AUW: 3200g
Retracts: Aluminum
LiPo: 6S 5000mAh LiPo (not included)

The plane it self comes in two versions, ARF or PNF. I choose the ARF, as I like to pop in HS65MG's all around. The ARF weighs 1650gram out of the box.(to compare with the Ready2fly Venom which is 1550grams) It's a nice design with alot of improvments that I like. For example, HS65's fits in the servo covers when this kind of plane usually is designed around $2 junk servos. The flaps are hinged correctly and can drop to almost 90 degrees out of the box. It also comes with an 11blade EDF unit which correctly balances should make a nice sounding plane. The stock PNF version is measured to 204km/h which is pretty good for a plane in this class. It's fitted with a sturdy CF tube wing spar and all parts fit togeather really smooth.

For those choosing EDF you might want to know the inlet area is just under 5000mm²(4950) and the tailcone is 80mm at it's smallest spot opening up to 82mm during the nozzle.

The Viperjet is a short aircraft which would make it perfect for a rear mounted turbine, but as the nose is all occupied with the front gear there is no way of fitting batteries and such in the nose, they have to go where the 6S flight pack usually would go. This calls for a thrust tube to avoid too much extra weight in the nose.

When setting it up with a Kolibri turbine it balances perfectly with two 1800mAh packs, when choosing a P20 you would have to add about 100grams of lead in the nose, or twin 2500 packs. With the Kolibri engine the dry weight is 2550grams, again 100grams heavier then the Venom, but still very light considering the EDF version is advertised at 3150grams AUW. I choose a 750cc fuel tank from GBR Jets, with it filled up I'm actually spot on the 3150gram mark. (With a P20 add 250grams to the AUW)

More to come after the test flight.

The viperjet assembled


Cut out of the stock ducting to fit the tank


I made CNC parts to mount the turbine and hold the thrust tube. Two rings in the duct and the small teeth to prevent it from going forward. The parts are available for Kolibri/P20 via [email protected] as usual.


Tank and radio in place. The tank simply CA glues in place using EPO blocks to wedge it firmly in place before glueing.

Bob_B

My Feedback: (11)

Henke love the use of nutserts for your turbine mount.

petera38

Hi Henke,

 Cute  foamie. How much did you pay for shipping?
 Looking forward to see your test flying report.

/Pete

essyou35

My Feedback: (11)

Are you using the stock retracts on that setup?

cyphur01

They look like the stock retracts to me. Check out the thread on rcgroups on this plane. I know that baobama hobby is going to be carrying this in the states.

Henke Torphammar

Thanks! They work very well. Next run of mounts will have the thrust tube hooks fixed too for a cleaner look

Henke Torphammar

Shipping of this bird to Sweden was $110 from Taft, will of course be cheaper as soon as our local dealers gets them in stock.

Henke Torphammar

Yes I do so far. There are alot of choices for upgrades if they won't last, but I thought I would try them out before buying new ones.

Henke Torphammar

I installed he smoke pump after a bit of thinking. It adds weight but is pretty cool. To compensate the weight gain I switched from my Kolibri T25 to one of my brand new T30's. Same size and weight, but completly new internals and 3.Xkg thrust (7.Xlb). The two T30's will go in to my Eurofighter later on. I'll probably make a new thread on the T30 later on and try to keep this thread on the Viperjet.

Henke Torphammar

Ok, it flies... and darn well too! It's very neutral and easy to fly. Very little coupling during knifedge. Needs a bit of down elevator when inverted but so does most planes. I feel very comfortable with the plane and did several knifedge passes just of the deck. It does not have insane rollrate, but keeps its response even at very slow speeds. Does not tipstall at all. Landed at my feet in a plesant speed.

It's more slippery then the R2F Venom. It's faster, but not by alot speaking topspeed, it does cruise faster on particial throttle though. For example it easily knifedges at half throttle which in my case equals 2.64lb of thrust(1/3 of the full power) in my case.

Only one flight due to "bad glow", would not have happend with a P20

lxfly

Hi Henke,

Nice Viper, congratulations for your maiden, would really like to have this flying field opportunity. What is your experience of flying these litte bird's on grass tracks?

Henke Torphammar

Hello,

We share this wonderful site with a glider club and some parachuters, they also prefer sunny weather so we also have a good dedicated club field with grass. As you know grass is not perfect and varies over the season, still there is not many problems caused by the gear, rather by pilot error. I have yet to fly the Viperjet of grass, it got smaller wheels and less suspention then the Venom of last year, so I simply don't know how it will do. The Venom did fine and the retract units lasts pretty well if not making too bad landings. I always keep a spare unit in my field box in case of failure. I actually prefer grass as my EPO planes don't have wheel breaks. check my youtube channel for video of the Venom flying of rough grass www.youtube.com/henke2

As for taking of, that has never been a problem with my setups.

Henke Torphammar

The Viperjet got alot of flights the past week. The airframe and gear is very strong! No problems with grass landing and takeoffs.(Update: The gear it self handles grass but the suspention is minimal and the wheels small making anything but a perfect landing a bad idéa. The retract units are strong but the struts are from soft material and will like any other china planes not last forever) It really loves knifedge flight and I found my self doing point rolls and slow rolls down on the deck after only a couple of flights. The airframe seem to have pretty low drag. I can do 8min of pretty fast sport flying on 600cc of fuel (landing with 150cc left). The previous Venom needed that for only 5-6min flying at way less speed.

With flaps the Viperjet slows down really well, much like the benchmark Venom. I would call it a draw which is the slowest flying. If you throttle up it moves well and the airframe easily handles my setup which I would say equals a 10-12S EDF setup in power. No problems with flutter or warping the wings. The spar also does a good job keeping the wings from bending during high G manovers.

Just need to pop in the new electric breaks from ready2fly :-)

Quandry

Very nice pics and looks like a lot of fun!!

lxfly

Nice Viperjet; very sad I couldn't come to the meeting these days (just a 100km drive)
Have fun.

Henke Torphammar

Some video of my ViperJet turbo. We were lucky to be alone at the airfield this beautiful but windy day. I made two flights and combined them to one video showing both fast and slow flying. When no wind the Viperjet is super smooth!

[youtube]http://www.youtube.com/watch?v=dRBrgJAUXjU[/youtube]

Henke Torphammar

I'm just converting my Viperjet with tamjets struts and the electro breaks (with turbine I need them to ever stop)

I use the Super Sniper struts which are disassembled to be shortend by about 1/2". One of the main wheels became the new nose wheel and the larger ready2fly breaked wheels will be the new mains.

Bob_B

My Feedback: (11)

Henke. you are having too much fun with your turbine foamy. Thanks for sharing.

Henke Torphammar

Thanks! Yeah it is fun! I like showing off what you can do when all knee shaking is removed from the jet flying. This is fool proof with a 3ft bouncy crush zone infront of the engine

Henke Torphammar

Nose gear is ready while the mains use temporary wheels(correct size) as the breaks haven't arrived yet. Useing temp wheels will make the foam cutting easier. I think it turned out pretty well. The suspention is super good now! Once again I encourage you to take the step and buy a set of real struts. They are very much worth their money and will move on to the next airframe too!

Henke Torphammar

I visited a meeting today flying my Viperjet. This was the windiest day I have ever flown in except when slopeing... also one of the hottest with tempratures of 92F(!)

With these extreme conditions the new Jeti DS-16 transmitter and it's tememetry was super good to have. Monitoring the fuel level is way better then using the timer in windy conditions like this.

The little Lambert turbine still puts out about 1:1 thrust to weight ratio even in this tempratures.

Also the first flights with the Tamjet struts... they are in another leuge compared to the stock ones. Super smooth suspention!





As hot as it gets here... 92F(!)

Henke Torphammar

One user got the Tamjets JT Viperjet struts for this one and they fit perfect, even with the doors after some shortening. Now with proper suspention and larger wheels it flies of grass too with stock power.

Chris Pyrah

Anyone Know if we have it available in the UK ?

DominicM

Nah. Nearest dealer is www.ready2fly.ch

Hugo777

Hi, you can buy in sweden to
http://mlhobby.com/flygplan/taft-hob...-edf-gron-epo/