|Dec 08, 2010, 07:46 PM|
EDF Nacelle fabrication & modifications. December 2012
Last Updated 01/22/13
December 8th 2012
A few guys have asked about the relocation of the EDF units I've talked about so I thought I would elaborate just a little here.
When I find a model that has limited or no access to the EDF unit, which is true of many of the earlier EDF designs but few of the newer ones, I automatically go about figuring out how to remedy that situation. Changing motors, rotors and even shrouds is a common part of the tweeking process for me so I need virtually every part of the EPS to be readily accessible and easily modified.
I'm a big believer that almost anything can be made to fly given the right mix of power to wing area and the proper CG. Since I'm not a great craftsman, KISS methodology virtually always prevails when I bash a kit. I start by determining where the most suitable/accessible position for the EDF unit would be. Once I've made that decision I go about making whatever changes are necessary, to make that location work. If I'm moving a fan unit rearwards 4 inches (the shorter the distance from the impeller to the compressed thrust point the better), then I know that I'll need to make the necessary offsetting changes to the anterior weight placement in order to maintain the AC's optimum CG.
This first series of pictures shows an ME-262's nacelle/EDF unit modification. Note in the first picture there is NO EDF unit visible now.
December 17 2012
Pictures 5 thru 7 are of a different nacelle modification. This one is for the Dynam ME262 which flies beautifully unmodified but looks much better after this mod.
Jan. 22 2013
Since modification is not always possible or practical it's sometimes necessary to fabricate the parts you need. Although it can be a time consuming venture, it can also be an inexpensive alternative to commercial products. Fabrication isn't as difficult as most might imagine and more over it's often times the only path to the desired result.
Picture 8 shows three different types of nacelles. All three were fabricated using two different techniques.
Left & Center - Ring Joined fabrication is by far the lightest but also structurally the weakest although it can be reinforced, as the one in the middle was, using the lamination technique. This type of fabrication works well for indoor models or any model that requires ultra light weigh and/or isn't likely to take much abuse. The nacelle on the far left of the picture weighs in at just under 10 grams and the one in the middle weighs only 11 grams even though over 70% of it is double walled and both desighed to house 70mm EDF fans.
Right - Laminated construction consists of three layers of cold rolled foam glued together using water based wood glue. This provides strength and allows for easy contouring via sanding. Laminated fabrication results in at the very least double the weight of the ring joined nacelles but is 10 times stronger.
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|Feb 27, 2013, 11:58 PM|
I see you have a lot of new work here on this entry but RCG thinks this blog is a couple years old and was trying to convince me not to post
Anyhow I like the work you've done on the nacelles. One of the reasons I haven't bothered to get the 262 is both Dynam and Freewing have over sized the nacelles and inlets and I didn't like the look and knew I'd have some work ahead of me as usual to make it look a bit better. For what reason they over sized the so much I'm not sure. It's pretty well proven any fan really does not need any more than 100% FSA and probably will get by fine with 85 percent on a straight duct like these have.
Anyhow you've made some great work out of those and the plane looks way better. I bet there is a much better inlet whoosh sound - imagine if you had some CS-12 70mm fans in there, it would sound even better!! (Exceed RC's 50" F-86 has 80%FSA inlets on the F-86 and that's stretching it a little but it flies awesome especially partial power, not like an over sized inlet will do with the speed brake feeling you get as soon as the throttle comes off).
Great work on all your stuff, the 717 looks good too.
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