It always amazes me the size of tanks people use. With a 70 fs I would use 6-8oz. That should give you 12 minutes.

yeah tis amazing not been using fs that long and their fuel economy still amazes me

eeemmm.... I have fallen out of hover more than once because of fuel.... as you could understand I`m afraid of small fuel tanks

User a timer (trick is to then remember to turn it on as you are taking off [&:])

yep and prob is if you richen the engine slightly you can make a big difference on fuel economy. thats what caused my capiche deadstick that you saw sprink.

I think the only other thing you can do to lighten the plane is to seriously lighten the structure during the build. I think it would be very interesting to try to make a kit from balsa wood half the standard thickness (and therefore half the weight and lighter than ply)

Carbon fibre prop for me is easiest on Synergy. I was really carefull when building it and the only places that i can save weight are really the exhaust and the prop. Got an Engel Modelbeau carbon 17X12 coming. 45g lighter than a 17X12 APC. As for exhaust well, mines quite light at mo already and id need to buy a new manifold and pipe mount etc etc. Plus mine is just so reliable as it is that i think il just leave it. Not pushing weight limit anyway so its not a big deal.

Angus

Wheels and Axles are big for me but another thing is the wing bolts and other hardware.. I got A plane once that used HUGE metal wing bolts when all it needed was the nylon ones.. Also alot of the smaller planes benefit from nylon LG bolts... Also 4-40 rods are much heavier than CF rods.. Also I've found that Alum. control horns (On the servo's) are nearly as light as the STOCK ones that come with the servo's... So If your goin to go with larger control horns go ahead and go with the alum. ones.

I like this thread... keep the ideas comin`!

What about wheels? I've been weighing the ones I have laying around, and the best I seem to be able to do is 28g/pair for some treaded 3" foamies on nylon hubs. They are ugly, though. I have some Dave Brown 3" foam wheels that are 40g before sanding, double ugly. And 2-1/2" Sullivan Skylites are 34g/pair - heavier, but the best looking and no doubt durable. I see that E-Flite has 2 1/2" wheels that are 24g/pair, but have never tried them. Are there better options people know about?
Tks,
-RB8

I will soon be building a 40 size profile with weight savings as my main goal. I will be shaving 4 ounces just using mini servos and adapters found here. http://www.readyheli.com/Custom_Heli...p/chp-g015.htm Futaba 9650's, hitec 5245's, and JR 9411's can all be made to fit in them. Also I am using a 640mah 15c 2 cell lipo with reg. Battery weight is 40 grams, reg is about 15. Just with those two mods I am saving 6 ounces easy. Should help offset the weight of the pipe. Does anyone know how much a macs pipe and header weighs for a 46?

Yeah, the Macs header is about 2 oz. lighter than the stock 46 AX muffler. I have an extra one, if you're interested send me a PM.

I think this thread is going on a bit too much about weight, a plane that is 20% heavier will still 3-D, as long as you have over 1:1 thrust :weight, its nice to have more, but not critical. Get it as light as possible, within reason. The main difference is recovery from stall to normal flight, the heavy plane will take longer(or more altitude)to get flying again, you can manage the transitions once you get to know the plane and you must have confidence in the engine, absolute confidence DOD.

It's a design philosophy, MM, like the way Colin Chapman designed his Lotuses to be minimalist. Less wheel weight means lighter suspension and springs, which means lighter subframes, etc. I think this is definitely a good strategy for an airplane, especially a 40-powered fun fly ship. Lighter planes are more responsive, consume less fuel, and have greater load carrying capability. I admire someone who picks a lighter, powerful engine (say an old but strong HP40) over just throwing on a new OS AX 55. Sure the 55 has more power, but it also carries a lot more weight, needs more fuel, bigger landing gear, and so on. Maybe all I'm saying is matching a power plant to an airframe is more than just cramming in as big an engine as one can fit (our predominate club philosophy, by the way).

-RB8

Great thread guys.

Thrust is not an antidote for wing loading.

BOB

I have to disagree with you MM. That is one of the biggest reasons some 3d planes fly like crap. 3D is all about wingloading. Putting a bigger motor on an already heavy airframe is making the problem worse. Yes a heavy plane can fly 3d, but a light plane 3d's well in most cases. Thats why the profiles out-perform most full fuse planes of the same size.

Well said BBagle1, and remember the smaller the airframe, the smaller the reynolds numbers and the more critical wing loading becomes.

Bob

I use a timer on all my planes but I would never remember to switch it on.
I have a Futaba 9c, I set up the timer so when the throttle stick goes just a bit over idle the timer starts.
Its easy to set up this way.

You can have some of the same "issues" with a lightly loaded 3-D plane too, CG, thrust lines, incidence,ect, you might still have to tweak a light plane. Of course I'd rather have the lighter plane too, then stall recovery would be much better, gives you more confidence to come down low to the deck, you dont need as much power & the engine has a lighter work load. But, put on enough horses in any decent 3-D plane,weight aside,it will still hover, harrier,TR,ect... Carden makes some of the heaviest giants scale planes, you should see them 3-D like crazy in videos, they have engines that can do the job, however, when it quits, thats where the difference is. Save all the weight you can, it is worth some effort, but some of the points made here are-- well---a bit excessive.

Not my Carden.

Bob

I am enjoying all the lightening ideas being discussed here. Keep them coming as I am one of those excessive lightening people. I have a 73" QQ yak(gen 2) around 10.5 lbs with a ys140 sport in the nose and gone through great lenghts to get it there. This season I will be adding a removable smoke system to it and will still have an exceptable wing loading. It is not fully installed yet but with all the components it just weighed in at 11lbs 2.2oz. If I can shave any more weight to make up for the 8oz tank of smoke fuel I'll be carrying on take off I am all for it.

Here is a few pictures of the CF mods I did. These are of my first yak but made the exact same modification to my generation 2 yak where the batteries and receiver are now back in the fuse.

Whats a Scale, A well designed plane won't care about a ounce or two, unless your talking foamy, A Moass between 5 1/2 to 6 1/4 lbs will fly perfect , in fact the heavy one will do some things better.

Get a Fusion 67" ARF, it comes in at the advertised weight even with a bigger engine, unlike most of the others that are way over weight. Then you spend another $100 or so trying to get it were it was "supposed" to be.