I'm thinking about building a jet for a combat situation, but I don't know if the wing will hold up to the high stresses of turns accelerattions, or any other high G forces. I plan to have a 60" wing and a fuse, that can house two MidiFan 480s and all accessories (Batteries, esc., receiver,etc.) My target weight would be about 5lbs.

It would probably look like the jet next to the helicopter above the link "magazine" with a shorter fuse. Any pointers you might have?

Not too sure whether you're talking about Minifan 480's or Midifans, but I seriously doubt you'll be able to keep the AUW for a twin EDF at or below 5 Lbs., especially on a model that's going to be the size you've described.

The airframe should be able to take the manuevering stresses, but this will be the least of your worries.

The first thing to consider is how you're going to get a beastie like this into the air. It will probably be a bit heavy for hand-launching, unless you or one of your flying buddies are Olympic javelin throwers. The catapults used for other combat models (ie: Warbirds LTD, etc) won't get an EDF up to flying speed without serious modifications. This leaves only bungee launching and ROG. Bungee launching is okay, but can be tricky for the inexperienced and retractable landing gear will add at least 12-16 oz. to the flying weight.

Another point to consider is that the combat manueverability of EDFs isn't really comparable to prop-driven/glow combat models. IMO, I'd fully expect to see them wax your tail feathers each and every flight as they'll be faster and more manueverable.

This doesn't even get into the area of costs. You can expect the power system for a twin minifan 480 EDF model, including fans, BL motors, BL speed controllers and HIPO batteries to cost anywhere between $700-$1000. This doesn't count the radio or airframe costs. Expect the Midi system to cost about $500 more as they'll need more batteries and more expensive BL motors and speed controllers.

I don't mean to dash your hopes on the rocks, but you might be better off building a prop-driven model that *looks* like a jet rather trying to use an twin EDF for combat.

YMMV,

Dan

I see. Well, I'm trying to make it look like the plane in this [link=http://www.gworksdesign.com/Pages/CUDA1.HTML]Website[/link] with a few mods.

-Wemotec Midifan (2)
-Possible Hacker b50 12Xl BL Motor
-And Lipoly Batts.

Price is not a worry for me. My club doesn't allow streamers and provides instrad infared combat systems

In addition to what Dan said I want to emphasize the points of size and combat maneuverability. A 60 inch wingspan is a big airplane. My old pattern airplanes have about a 60 inch wingspan and they had a .60 gas engine in them and weighed (unfortunately) more than 5 pounds - closer to 7. The electric ducted twin jet in the video is a good looking airplane but note the flying style in the demo. Big open maneuvers while fast make the airplane into a target, not a fighter. Turn tight and the slow acceleration will make your airplane the object of the attention of everyone else flying.

Aha! Gordon's `Cuda.

At this point, your best bet is to go over to the EZone jet forum and start reading so you'll know which controllers/battery pack cell counts will work best with the motors and fans you want to use.

You'll also find the plane's designer, Gordon (Plane Crazy) there, too.

While you're there, take the time to become intimately familiar with LIPOs by reading up on them in the Batteries/Chargers forum. They require a completely different mindset than nickel-based batteries. Nickel-based batteries don't generally cause fires if they're abused, but LIPOs can and have, so please be very careful with them.

If performance is what you're after and price is really no option, then you might want to consider [link=http://www.shredair.com/fan.html]Schübeler[/link] or [link=http://www.jepe.org]JePe[/link] fans instead of the Wemotecs. The Wemos work great, but can't hold a candle to either the Schubies or the JePes in terms of pure performance. Naturally, all this performance comes with a steep price tag.

Good luck!

Dan

If that is the case, then what are reccomended characteristics for a fast but manuverable plane?

In a model combat scenario, jets vs props, jets will always loose. Top speed dont mean anything in that world, a prop can accelerate quite fast and turn on a dime compared to a jet. The only fair battle would be jet vs jet.....then would be fun to watch.

Ignoring for the moment the propulsion, there is no difference between a maneuverable jet or a maneuverable prop airplane. What ever configuration works for one will work for another. You need low wing loading, light weight, large surfaces (well large enough to turn the airplane rapidly) and low moments of inertia.

Any airplane that fits those requirements will work. Look at the airplanes used in RC combat today. Ugly but good maneuvering machines.

Throw in the powerplant and the airplane still should be the same. If either prop or jet produces the same thrust for equal airspeeds then both will fly equally well. Its just F=ma.

The problem I believe is that there is a variation in airspeed between the prop and the ducted fan jet that allows the prop to develop more thrust for a given power input than a ducted fan.

With a big and powerful enough ducted fan it would certainly beat up on a prop airplane but with our technology that is not likely to happen.

Put a nicely swept twin ducted fan of the type you are talking about against a mean junk dog combat model and the ducted fan model becomes a target.

Did I miss anything here guys, I have a migraine and am trying to keep my mind off it with the forum. However the headache makes me tend to go senile at the same time (well that's what my wife says). No she is sweet, she let me buy a new Canon 1Ds to take airplane photos with next year. Look out Joe Nall, here I come.

Yes Ben, you forgot something.....go take a tylenol before it gets worst.

Similar sized planes, electric and prop, the electric carries a serious weight penalty. The prop plane will outmanuver it.

I guess it's abit unpractical, but there's something that woulod make a jet as maneuverable (or even better) as a prop combat airplane. Thrust vectoring coupled with fun-fly control surfaces. An airplane with this configuration would be radically maneuverable. But the aircraft would need to be very light, or the engine a big one, say a single .91 Ducted Fan in a 50" span model, with a light but strong structure, and an AUW of no more than 70% of the fan's max thrust. Put some vanes in the jet exhaust to vector the thrust and there you go.

I guess it would be an interesting experiment, but i see that all this hassle for a combat plane is kind of unnecesary.

Just my 2 cents....

I was thinking of an EDF not glow/gas

How does an EDF have a weight penalty?

I plan not to use landing gear but rather, ball-casters like [link=http://www.robotcombat.com/marketplace_ant_wheels.html]this[/link]. And Ball-bearings like [link=http://www.wmberg.com/catalog/catresults.cfm?CatType=BEARINGS&CatGroup=BALL%20BE ARINGS]this[/link]

Weight penalty...
BATTERIES!