Masher Posted February 21, 2013 Share Posted February 21, 2013 Hi I recently aquired an old Avicraft Frantic airframe which had previously been running with a ~40 size IC engine. The model is in good condition and the previous owner said it was a very good flyer so I want to get it back in the air. If possible, I want to convert this to electric so that I can fly down the local field without annoying anyone. Today I have fitted it out with what I had to hand including a 40A ESC, a C35 series motor (550W max) and a 3s 2200 Lipo. As it stands, I have mounted the motor direct to the firewall and with everything as far forward as possible, the CofG comes out at about 145mm back from LE which is about 50% of the MAC (270mm). I am assuming that I want the CofG to be about 25% of MAC (I am an improver, not experienced) so I have to get the CofG moved about 55mm forward!!! (ie 25% of 270 ~ 70mm). Even with a 200g weight stuck to the prop, the CofG only moves about 20mm forward so I need to do a lot more. The weight of a typical 0.46 engine with silencer is about 200g greater than my motor and Lipo. So what is the best way forward? Assume mounting the motor on pillars will not be enough. Next idea would be to build a motor mounting box fixed to firewal. Then presumably need to get the Lipo ahead of existing bulkhead but this would be getting very "long-nosey". Any help, advise would be greatfully received Thanks in anticipation I can post a photo if this helps Martin Quote Link to comment Share on other sites More sharing options...
Ruprect Spode Posted February 21, 2013 Share Posted February 21, 2013 Hello, do you have room for 2 lipo's up front? Quote Link to comment Share on other sites More sharing options...
Masher Posted February 21, 2013 Author Share Posted February 21, 2013 Yes I could probably fit 2 in, I'll try it and see what it does to the CofG Quote Link to comment Share on other sites More sharing options...
Masher Posted February 21, 2013 Author Share Posted February 21, 2013 Well that only brought it forward by about 10mm - seems miles out as adding the extra battery (+195g) should make same total weight as with IC. Quote Link to comment Share on other sites More sharing options...
kc Posted February 21, 2013 Share Posted February 21, 2013 You asked elsewhere about the CG on the Mini Frantic for reference. It is stated as 60mm back from LE . Chord including elevator is 260mm at widest part. so thats 23percent. Note the Mini Frantic may differ in some ways not just smaller. Best to phone Avicraft 0208 4600818 and ask for the precise info. They will advise on electric I am sure. . Rob or Ali are very helpful ---it's a great traditional modelshop. Quote Link to comment Share on other sites More sharing options...
Masher Posted February 21, 2013 Author Share Posted February 21, 2013 Thanks KC, I have emailed Avicraft for help also. Quote Link to comment Share on other sites More sharing options...
kc Posted February 21, 2013 Share Posted February 21, 2013 They are often slow to answer e-mails sometimes, better to phone. On the Mini Frantic I have decided to lengthen the nose to allow the Lipo to come well forward to help CG. I have just chopped off the front and will rebuild using a liteply battery tray to help strengthen the joint. On other models I put the seperate Nicad under the battery tray and the Lopo on top. Nicad is more useful weight than lead! Of course on a used IC model you need to consider whether it is oil soaked and wont take glue properly. Quote Link to comment Share on other sites More sharing options...
Masher Posted July 13, 2013 Author Share Posted July 13, 2013 Just to close this out, Avicraft never responded to my email. In the last couple of weeks, after seeing our club chairman having loads of fun with an IC Limbo Dancer, I fitted the Frantic out with an Irvine 36 2 stroke. What a blast - this plane will do anything without complaining! The CofG came out at 33% which seems to be fine. I read elsewhere that these planes are not fussy at all - that seems to be true. Don't understand why Avicraft don't make these anymore - would sell like hot cakes I would have thought Quote Link to comment Share on other sites More sharing options...
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