Bruce Richards Posted February 25, 2009 Share Posted February 25, 2009 I am just completing the assembly of a Seagull Extra 300S and to get the CofG at the right place I was considering cable tying the Rx battery to the engine mount. Has anyone ever done this before? I am concerned that heat from the engine will affect the Nmhi battery. It has gone together really easily an looks a nice model. I do not want to add dead weight just to get it to balance. Quote Link to comment Share on other sites More sharing options...
Doug Ireland Posted February 25, 2009 Share Posted February 25, 2009 Hi Bruce, I'd be more concerned with vibration rather than heat. I have mounted battery packs between the engine bearers before now but always made sure they were completely encased in foam first. Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted February 25, 2009 Author Share Posted February 25, 2009 Thanks Doug good point Quote Link to comment Share on other sites More sharing options...
David Perry Posted February 25, 2009 Share Posted February 25, 2009 And I pop mine in a freezer bag to avoid ingress of fuel aand oil. D Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 25, 2009 Share Posted February 25, 2009 That's odd - on mine, the battery is cable tied behind the former at the trailing edge of the wings! What engine have you got - a Cox .049??? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 25, 2009 Share Posted February 25, 2009 I did once make up a foam lined ply box to fit a battery alongside the engine on a particularly tail heavy Airsail Tomahawk that I was given by the builder who'd given up on getting it airborne. Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted February 26, 2009 Author Share Posted February 26, 2009 Martin, I have an ASP .75 2 stroke in it, that is not particularly light. What do you have in yours? Where is your CofG? The instructions sat 40mm from LE at the wing tip. Looks a long way forward to me. Better that than too far back Quote Link to comment Share on other sites More sharing options...
Andy Green Posted February 26, 2009 Share Posted February 26, 2009 'And I pop mine in a freezer bag to avoid ingress of fuel aand oil.' Have you thought of using a balloon, you have to struggle a bit to get the pack in, but very neat once you do. Andy Quote Link to comment Share on other sites More sharing options...
David Perry Posted February 26, 2009 Share Posted February 26, 2009 Andy, neat idea. I'll try that. D Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 26, 2009 Share Posted February 26, 2009 Bruce, I have gone slightly over the top with a Super Tigre 90 (but it shouldn't be appreciably heavier than your 75, I'd have thought) as it was the only suitable engine I had when (thanks David and Co.) I rather unexpectedly won the model on an email comp on this site. I marked the C of G using a string stretched between the specified wingtip positions onto the fuselage (marked with black spots in the photo below) for easier balancing. You can see my battery at the rear of the hatch opening. One thing I did notice when checking it is that fitting the wings made at least an inch rearward difference to the C of G position, which surprised me as I often assume the wings won't affect the C of G on models very much! Once the wings were on it did balance on the markings. The main departures I made from standard were to substitute a SLEC tank as I was concerned about the original's capacity and eventually added canopy catches as the bolts were a pain in the wotsit! By the way, did your tank fit in OK? My original one wouldn't fit past a step in the front former so I needed to get the Dremel and files out anyway which simplified the decision to fit the larger tank. Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted February 26, 2009 Author Share Posted February 26, 2009 Martin, Your picture looks very different to my model. Mine is the Seagull Extra 300S .60 size and there is no canopy hatch. Access to gear is buy removing the wing which is in one piece and fits on from below. My tank fitted perfectly but does look a bit small. I have now fitted the cowl , which I did not think would make much difference, and I think I can get away with the battery on top of the front of the tank. Thanks for your help Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 26, 2009 Share Posted February 26, 2009 Mine is the 5500198 SEAGULL EXTRA 300S (61-75 SIZE) (SEA-70B) Wingspan - 63ins (160cm) I can't see another 300S on Perkins' site but perhaps yours is an older (or newer) version not stocked by them? Anyway, feel free to ignore all I've said so far!!! Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted February 26, 2009 Author Share Posted February 26, 2009 Mine is the cheap one Here . Your comments were helpful and I have go the CofG spot on now. Hopefuly a maiden tomorrow weather [permitting. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 26, 2009 Share Posted February 26, 2009 Glad to have been of some help. Hopefully yours will fly a well as mine - I've flown a variety of Extras and without exception, they have all flown extremely well. There is something fundamentally right with the design that seems to translate to models of all sizes. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.