Posts: 34
Joined: 1/31/2003 From: EverettPA, USA Status: offline
Good ideas everyone, any of them would work well giving the amount of time you want to spend working on it, but I think we are all over stating a very simple problem it is just weight. Just find something dense and put it where you need it and secure it very tight. But me personally I am going to stick with the depleted uranium it is always nice and warm, but a real pain to shape.
Posts: 4047
Joined: 12/23/2001 From: Kingman, AZ, USA Status: offline
For scale airplanes with raidial engine cowling and a short nose moment arm, airplanes that do frequently have balence problems particularly with two stroke glow engines here is a neat and effective method: Obtain some lead bar stock and cut a length sufficient to approximate the needed weight and drill two holes a couple of inchs apart. Now go to the the lighting fixture department and purchase some lamp tubes. These are hollow threaded tubes in various lengths (the threads will be unused). Needed next are a couple of lengths of all thread 10-24 or thereabouts. The lead bar will be positioned imediately behind the cowl opening under the engine or to the side if the engine is mounted sideways (positioned to clear any muffler consideration). The firewall is drilled with holes to match those in the lead bar and the all thread goes through the lead, lamp tube and the firewall, nutted with washers on both sids of the firewall and tightened down. Nuts safetied however you like. The weight is just behind the prop and no need for crankshaft weights which I abhor and extremely secure. Have used this technique on several WW I ships and it proved reliable, effective but most of all easy to do.
Posts: 355
Joined: 3/28/2003 From: Greentown,
IN, USA Status: offline
A friend of mine once put a trailer hitch ball in the nose of one of his planes to get it to balance. I of course asked if he would be pulling a trailer with it.
Posts: 333
Joined: 11/9/2002 From: Roanoke, VA, USA Status: offline
hi skylane42
what I use is buckshot, as used for shotgun shells. weight needed is easily adjusted and it can be placed in fuselage and epoxy added to secure in location. give it a try, you will like it.
Posts: 333
Joined: 11/9/2002 From: Roanoke, VA, USA Status: offline
hi skylane42
what I use is buckshot, as used for shotgun shells. weight needed is easily adjusted and it can be placed in fuselage and epoxy added to secure in location. give it a try, you will like it.
Posts: 1809
Joined: 7/6/2003 From: STATESBORO,
GA, USA Status: offline
quote:
ORIGINAL: pt19 flyer
hi skylane42
what I use is buckshot, as used for shotgun shells. weight needed is easily adjusted and it can be placed in fuselage and epoxy added to secure in location. give it a try, you will like it.
happy flying pt19 flyer
I agree except that if you use a smaller size than any of the "buck" sizes :000, 00, 0 #1, #4"buck) and use the smaller shot sizes such as #9, 8, etc much finer increments of weight can be obtained. If one does not wish to melt and cast lead I would recommend forming a mix of #9 shot (finer if available, but #9 is normaly easily and economically obtained) and epoxy to create a lead/epoxy rod, sheet, bar- whatever form suits your purpose.
The homogeneous weight formed by molding molten lead is, of course denser and more space efficient.
Posts: 4657
Joined: 12/11/2001 From: Upplands Vasby, SWEDEN Status: offline
Hi! It's not a fallacy, at least not in competition circles....light weight is something that racers always strive for but many sportpilots never seems to understand the importance of . I know that certain airplanes (sailplanes) benefit from adding weight at certain times but that does not apply to most other airplanes in the sport, scale and pylonracing category- Being myself a pylonracer competitor (and scale) for nearly 30 years I can assure you that weight is very to important minimize. The reason is simple.....low wing loading makes airplanes generally faster, they accelerates faster, turns tighter, have lower stall speed and are easier to land. Therefore I always try to build as light pylon, scale and sport airplanes as I could...as I know that they fly better this way and will last longer too! Therefore I never ad lead whenever I can. Of course lead should be added if there is no possible way of reaching the correct C of G but most of the time the correct balancing point could be reached instead of adding weight. Moving servos, batteries and radio gear or carving away wood at the tail or changing to a lighter rear wheel is things I would consider first.
Take my my own constructed Henschel 129 as an example..the first example of this Aircombat twin engined fighter weighted 1560g (1,56kg) and had a span of 110cm and it flew good but its performance wasn't too good...A lighter version was built and it weighted in at 1350g (1,35kg) and flew much better having much better handling characteristics and was easier too land due to its lower wing loading
A second example, Our clubs two trainer aircraft (highwinged Kyosho trainers with a span of 160-170cm) weighted both 2400g (2,4kg) in original form, powered by two .40 engines. Lightened and rebuilt both airplanes weighted 1800g (1,8kg) and both could be powered by smaller lighter.28 engines instead of the .40 engines used previously.Both planes could now be flown much slower, having much slower landing speed than before and having much better handling characteristics due to the lower wing loading. A third example: My Kyosho PBY Catalina powered by two OS LA .15 engines that was lightened by removing the original wing covering and taking up holes in the foam wing and then covering it with light Oracover plastic film and using micro servos for all controls and wires for all control surfaces...it too flies better at 2,5 kg than the original airplane at 2,7kg. Regards! Jan K Sweden
< Message edited by jaka -- 12/4/2004 11:05:56 PM >
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Jan Karlsson Airracing products MVVS, Motul "Micro" all synthetic oil
Posts: 17
Joined: 7/15/2004 From: , VA, USA Status: offline
I usually bolt on more horsepower. no free rides for extra weight. I mock up the plane, determine the approximate weight required to balance the plane, then look for the right size engine to balance. I usually end up with a plane with that has the "next size up" engine. I only use lead to make small balance changes. Large changes, mean a bigger engine! cheers, Bob
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RE: what to use for balance??? - 
