Probably the number one question we get in our inbox is whether we have documentation to convert some of our excellent RC "pusher" prop plans into EDF, or electric ducted fans power. Since we get the question all the time, we thought we would spend a little time discussing our feelings on the whole subject. If you are roaming around your local hobby shop, you will notice a lot of the boxed RC airplanes come set up for EDF. So it has a lot of RC builders wondering if its a right fit for them. Let's break this down a little.
First, several of our plans are excellent candidates for EDF conversions. The excellent F-14 and F-22 designed by Steve Shumate both will accommidate EDF fans. Both of these parkjets require dual fans, which works out great anyway. And don't forget, parkjets offers several models designed specifically for EDF. So check those out too. But with each of these conversions, the builder will have to make some adjustments to the original design like moving some pivot rods, perhaps enlarging some areas and of course working on ways to mount up the system inside the airframe. The result is pretty neat. They look and sound just like a mini version of the real thing. The F4D Skyray is also an excellent candidate for EDF conversion and in this case is pretty well documented with instuctions and pictures.
For the profile type RC parkjet, we have seen a very simple and very effective EDF conversion. It doesn't really offer the scale look, but offers an alternative to the mid mounted pusher prop that most of the designs have been built around. Below is an excellent video of the Tomas Hellberg F-22 with an EDF fan strapped to it. Most of the Tomas Hellberg plans would work well for this type of simple conversion.
You can see the builder just made a little modification and everything worked well. There are other videos of him flying the jet and it works quite well. The F-22 is a very versitile airframe.
So what do we think about conversions? Well, its complicated. We know there are some modelers out there who would rather not have an airplane than stick a prop on the back of a jet. It just seems so...wrong. We get that all the time. The EDF offers a lot of speed, no real torque and good speed. Some modelers are just looking for something different too. And we can certainly appreciate the attitude. Sometimes a builder wants to venture into a little different RC hobby.
However, for us, we like to stick to the prop. The 6 x 4 prop on one of these parkjets performs so well. The effeciency is through the roof, especially compared to EDF. Your battery will last longer, you need a smaller electronic speed control, the battery doesnt get as hot, and flight times are generally longer with the prop. Also, the thrust off the bat is so much better that a prop driven plane is often easier to hand launch. The reason is that the prop just grabs and moves so much more air in a single rotation that it leads to more bang for the Watt. EDF has to work so much harder than the prop to move the same amount of air. Of course, we all know that sometimes giving up a little gas mileage is worth the cool factor right? I mean, not everyone wants EFFECIENT when you can have a SLEEK right? So what about those RC pilots out there that want and must have and EDF driven airplane?
Well, luckily, EDF is getting better. And frankly, its darn near taking over the industry. At least from those models that come out of the box. Our recommendations is to stick to the bigger fans (68mm and up) and make sure you have a good wide airframe like the F-22, F-18 or even a delta type wingspan like the F4D.
And remember, when you toss that EDF for the first time, give it a heave, because that fan won't start to really push the air until it winds up and gets the plane moving through the air. Your thrust is limited at first.
You have heard our thoughts, now tell us what you think. EDF or Prop? There is no wrong answer as long as you are out there building RC airplanes from scratch or plans. You can't go wrong.