Henke Torphammar

I bought one of the new(?!) Feibao Eurofighters at the Feibao stand at Jetpower 2012. It's approx scale 1/9.5 which makes is 1650mm long and 1200mm wingspan. It's also the Sportswagon version(2 seater) which I think looks better and I like the idea of more fuselage area for knifedge flying. It's advertised for EDF, either twin 90mm units or one 110mm unit such as Schubeler HST77 or Vasa 14blade 110mm. It can also be equipped with a 6kg thrust turbine.

However those setups tend to get too heavy for my taste so I choose another path going with twin Lambert Kolibri T25 engines. I will try to explain why in this thread.

This airplane seem pretty new under the sun and I have not found many flying. There are one present with a Vasa 110mm EDF, AUW 7000grams.(Demoed at jetpower) Another one with twin 90mm units are weighing in just under 6000grams. Looking around I also came across the red leader Eurofighter, but it's smaller and not really good to compare with. Another one is the Grumania 1/10 Eurofighter in simular size advertised at 7500grams fuled up with a single 6kg thrust turbine. That would make about 6500grams dry... I think I can beat that too.

The way it should work are that a single larger engine would be much lighter for the same thrust, however when reading the figures in the RCJI turbine test issue you find that a Jetcat P60(which for many is the obvious 6kg thrust choice) weights 870grams and provides 5800grams of thrust. In the Eurofighter it would need a bifurcated pipe which atleast do not increase the thrust, probably rather shave some of. The installed weight with 5mins of fuel are 2700grams according to RCJI.

The Lambert Kolibri T25 is a little power house for sure. For the twin T25's we are looking at a combined engine weight of just over 500grams and a thrust figure about the same as the P60. The dual engines will not need a bifurcated pipe. They will infact not need any pipe at all if I can manage the CG with them mounted in the rear which of course means the full thrust will be kept.

Now by chooseing compontents with care I think I can set this one up with a full house includeing gyro stabilisation and breaks alot lighter then what we see with EDF or single turbine.


The Eurofighter Sportswagon right out of the box, 2100grams.

bidrseed2

My Feedback: (2)

Hi Henke,
I bought this model in 2011, but have yet to start building.
(I bought the larger 1:7 scale euro at jetpower in 2012)
I'll follow your efforts with great interest.

My example weighed 5lbs out of the box.
If you can buid it as a twin with a take off weight of 10lbs, I'd be very impressed/surprised.

hooker53

My Feedback: (106)

Hello Henke. Very nice looking Euro. Looks like you have done your homework. I have the Grumania 1/10. Still in the box. I will be watching your thread and thanks for sharing this. Good luck with your build. I hope you get real I depth. Lol.

Henke Torphammar

This is my first project where I tried to calculate the AUW even before the build started. I gatherd all components I was recomended to use in an excel file and made the computer sum it up. I found the excel sheet very helpful when playing with diffrent weights. I never thougt it would be this good to put it all in a list.

This is how it looks when I added all components I was recomended from the manual and from Jetpower.

Based on Lado retracts, Jet 1A lets/wheels and GBRjets electric breaks.

Pepperpete

What a nice size! Who will be doing the pipe?

Henke Torphammar

I wan't happy with the weight of the components suggested in the manual. I see no point in useing standard sized servos when you can get the same performance from a much smaller unit now days. I remade my calculations with lighter yet good parts. The electric retracts had to go.


New calculation based on Futaba BLS servos, Jet 1A retracts from Savex L39, Break only on the front wheel and the engines mounted in the back(!)

Henke Torphammar

I don't think I will need one if I can get the CG right with engines mounted in the back.

Henke Torphammar

As the AUW seem to be low enough for the smaller Jet-1a spring airs I started drawing parts to be CNC milled at HAB. The G10 parts do add weight, so I still don't want to ass too much material, but as long as it's not behind the CG it's not too bad. Also the stock formers for the nose retract looked a bit on the weak side. When mounting the engines in the rear I also gain the possibility of haveing the fuel exactly on the CG, without fiddeling with split tanks mounted on the sides. Many of the parts I design has multiple features. The fuel tank holder also doubles as reinforcement for the fuselages bottom, where the nose gear retracts.

I like the way GZ mounts the steering servo, so I'm trying to incorporate that to my design too.

http://www.gz-retracts.com/

Pepperpete

Very facinating thread. Looking forward to seeing more.

Bob_B

My Feedback: (11)

Henke. i like. i like your approach to weight savings. Was that your schubi Hawk with the t 25 that took of in about 30 feet?

Henke Torphammar

No, it belongs to a friend, Dirk Böhle in Germany. While at it spending almost 3grand om a turbine you might aswell go for the proper airframe to make it justice not shaving $400 of from the total by shopping at Hobbyking

Henke Torphammar

Some of the parts needed are getting ready for the router. It takes alot more time then you think to make everything fit. To get a proper view of things I do draw all components around too, not only the parts to be manufactured. A bit more work, but very much easier to get the whole picture, even for checking CG before the parts exsit IRL.

Henke Torphammar

Another positive side of making all in CAD is that the 3D printer comes in handy

Bob_B

My Feedback: (11)

Very cool.

kimhey

More, more! Exciting project Henke

Pepperpete

I agree I must see more!!

Henke Torphammar

Now all parts are drawn ready for the CNC router. My local dealer have a great router which is normally used for manufacturing multicopters used for firefighting or videoing other places where you don't want to be in person such as African wild life. For you who have read my previous build logs this it old news. Still worth alot to have access to a machine like this. Almost never are the supplied hardware right for you. Why use a control horn thats almost right when you can make one for your exact purposes?

I hope the new parts will be in soon

[youtube]http://www.youtube.com/watch?v=c09ubYYvFVI[/youtube]

Henke Torphammar

The 3D puzzle from HAB is in!! Now I need to trim the attachment points from all parts and sand the surfaces that will be glued. And of course correct any misstakes I made when drawing the parts.

I think there will be only minor changes not needing another go in the CNC router. Expect more pics during the weekend. I bought a ZTE as a transfer phone until the Galaxy S4 is out but I think I need to get a Galaxy S3 meanwhile, blurry pix [:@]

bidrseed2

My Feedback: (2)

Henke,
If you were thinking of having a second set of parts machined, I know someone who would be interested......
(hint, it's me)

Henke Torphammar

Do you want a complete kit for Kolibri convertion or just parts of the set? This includes controll horns, brackets for landing gear, fuel tank holder, engine mounts etc...

Henke Torphammar

After some preparation I've started the assembly of the CNC cut parts. They are puzzled together and fixed with thin CA-glue. I bought syringes in various sizes from www.dx.com, perfect for applying small amounts of CA in the right places. When glued the structures get insanely strong. Both turbine mount and tank mount doubles as reinforcement of the airframe.

Seems to fit well and from what I can tell CG seem to be in the right area too, even with the twin engines mounted far back. Everything is not in place but still good enough to choose this path for the project with fingers crossed

Pepperpete

Looking great!

Henke Torphammar

Fueltank glued in place. I use 24h expoy glue mixed with a thickener and some dye. I do not know how this compares to Loctite 9462 or 9466 but it applies in a simular way useing a larger syringe. The nozzle extends if needed by useing any kind of fuel tubeing or even a large needle.

Small steps now as the glue needs good cureing befire next step of the build

Henke Torphammar

Engine mount glued in place. Carbon flock did not work with my syringe technique, only the glue came out of the nozzle leaving most of the flock in the syringe like a sponge. Not a big problem, but a little more dripping then I would have liked. As always alot of aligning and eyeballing before fixing it to cure. Feels solid anv very light. CG still seem to be within reach

Henke Torphammar

Service panel with filling of fluids, air and charge of the battery packs. After fitting the panel I found that this apparently is a pretty standard feature of a turbine RC Eurofighter. Why google first, when you can do it later? haha






V1 which did not fit due to the noswheel. [&:]