envallm

HI All,

I've decided to built a F-18 Hornet Single ducted fan from Yellow Aircraft. This is my first jet. I am very excited about building it. I wonder if any of the veteran modellers can give any advice eitehr about this particular model or buildign ducted fan jets in general. I plan on using a Dynamax Tractor fan, OS .91 engine, scale Oleo metal struts, brakes, the works. I've only been in the hobby about 6 months, but have progressed very quickly. I plan on taking it slow with this model and not flying until I am absolutely ready. ONe big question I have is do I need to have a rudder on this model. Some say yes, others now. Basically the neigh sayers stance is..dont fly in crosswinds.

I plan on using the Blue Angels color scheme. Any suggestions on painting would be greatly appreciated.

Thanks in advance

normgoyer

You should be aware that ducted fan jet models are yesterday's technology. The only advancement in ducted fans has been in the movement towards electric ducted fans. Other than that it is all real turbine engines. If you can find a group that still flies this type of aircraft hook up with them as a club with all turbines might not fully accept you and your model. Norm

envallm

Thanks for the heads up norm. The power plant used by the model can certainly accomodate a 12-17lb thrust turbine, if my budget becomes accomodating in the future. Right now, I am really concerned about any tips and techniques that the veterans on this forum (the small simple things that first time builders dont do) that might make tings easier. I am also specifically looking for any tips and recommendations about the type of paint to use. Someone in my club recommended automobile paint.

Thanks - everyone is a first timer some time...

Edgar Perez

My Feedback: (13)

Go ask in the RC jet forum. Most of the turbine fliers started with DF. Alsouse the search function. Lots of info.

Pushrod02

My Feedback: (16)

Check out this link. There are all kinds of people still running DF around here. Good luck with your project! http://www.rcuniverse.com/forum/m_52...tm.htm#6109603

gboulton

My Feedback: (15)

Not terribly long ago, I built Bob Parkinon's Regal Eagle F-15, powered by exactly the same setup you're considering. Though things did not go as well as I'd have liked with that airplane, I certainly learned TONS (it was not only my first DF, but also my first kit build). A few things I'll share, for whatever they're worth:

1) Give serious consideration to acquiring, mounting, and using an in-flight mixture adjustment system. These engines run right on the edge to produce the thrust required, and you'll absolutely want to be able to richen the motor a bit once the airplane's in the air.

2) Light, light, light, and lighter. Build as light as you possibly can. Obviously important for any model, I learned it's even MORE so for DF jets. To begin with, the Dynamax doesn't produce as much static thrust as some other fans, so you'll want it as light as possible to gain flying speed quickly. Secondly, and more importantly, remember that there's NO prop wash over any of your control surfaces, so as you approach the stalling angle of attack, the control surfaces become more and more useless. Keeping the weight down, obviously, improves low speed characteristics a great deal.

3) When mounting the tuned pipe, be careful about using metal pipe hangers. Not saying don't do it, but just be aware that if you do, you might get some interference from the metal-metal contact. Again, not a terribly difficult issue to resolve, but it can be a frustrating one to troubleshoot if you're not expecting it.

4) Again with the no prop-wash...pay close attention to the angle of incidence of the wings as the plane sits on the ground. The manufacturer will recommend the correct setting...follow it. Without the prop was over the tail, you'll find during take off rolls that the airplane is greatly dependant upon that angle being correct to get off the ground at the right airspeed, if at all.

5) Tail heavy is bad. VERY bad.

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Finally, this isn't "a caution" or whatever, but rather just sharing an opinion. Before completely committing to this project as described in your OP, at least CONSIDER going electric. That aircraft's large enough to carry a couple of good sized EDF units, and you'll find them not a whole lot more expensive than the 91 VRDF/Fan/pipe combo. I can definitely tell you that glow powered DF can become a REAL hassle at the field, dealing with sometimes awkward fuel systems, precise needle settings, starter probes, the works. Not to say it's not doable 9obviously...thousands do it)...just that it'll be a new set of hassles for you to get used to. Electric is cleaner, significantly less hassle, and as an added bonus, SOUNDS cooler too. I'm not sure how big that specific aircraft is, or what kind of thrust it needs, but imo it'd at least be worth a call to Hobby Lobby in Nashville...talk to Robert Harrington, and ask him about the big EDF units they have in R&D right now...probably at least worth spending a few minutes on the phone with him.

Good luck, and have fun!