I agree, the pilot needs work Opjose. In fact I havent flown in close to six months because our field was out of operation with tall uncut grass. I also agree with nose weight and throttle management comments you make, just I dont want to lose the airplane in gaining those skills back.

If 0.1 to .2kgs is not much of a weight gain (actually its 0.4 to 0.5kg gain as the stock should be 3.4kg) I am not too concerned. I am practicing on the sim already with scale models to get the throttle management and glide slope correct

No, I cant rebuild the tail etc. Remember, I have no counter weight anywhere in the airplane. Making the tail lighter will only make it more nose heavy.

The measures I had identified to lose weight were CF LG, foam wheels, LiFe for ignition (I am using NiMH now). I didnt use the CF gear because they told me CF is brittle (though Hobbyking was saying this gear is unbreakable). I already have foam wheels on it. I dont have a additional LiFe battery. If a capacity of around 2000mAh is recommended, its weight will be close to that of a NiMh.

I was thinking of 1300mAh with diodes in series, will that be sufficient for ignition for max 5 flights of 10mins?

Where else can the model lose weight?

Ameyam

To lose additional weight, use a wood prop and CF spinner. If you fly 2.4 then you might want to consider using one battery for both ignition and Rx power.

Karol

Yes, I did consider one battery. I am using the TH-8 module. But they told me it not advisable both on the RCU forum and on my field. Thats why I asked what are the safe ways to reduce lose weight

Ameyam

You're over thinking it.

The weight is FINE as is, don't screw with that any more.

Instead learn to land with a bit more throttle.

I teach students to fly the plane high and keep bringing the throttle back SLOWLY as they fly until they find the point that the plane will begin to no longer fly level no matter what you do with the elevator, and rather decends in a controlled manner.

That's the throttle setting you want to use until the plane is just inches over the runway. Once it's less than a foot above the runway, you chop the throttle completely while holding it as level as you can, and it will decend and land by itself.

It is so low at this point that tip stalls or regular stalls are merely "landings".

Excellent advice.

Karol

There is only one more 'safe' way to loose weight with this ARF...remove the engine, ignition module and battery, and replace it with the comparable glow motor. Then you move the tail mounted servos to the cabin area, and maybe rebuild the tail surfaces, to rebalance. There really isn't any other thing you can reasonably do to remove enough weight to make a difference.
Evan, WB #12.

Obviously you either havent flown aerobatics much or you have never taken the time to set them up correctly. A properly set up Extra is one of the easiest airplanes to fly. If you doubt that then I suggest you download the current IMAC unlimited sequence and imagine trying to fly it with an airplane that is difficult to fly. The only difference between a trainer and this sort of airplane is that an Extra has no self righting tendencies, it will go where pointed but is very predictable and forgiving. The fact that an airplane will fly 3D at all is proof positive that it is no harder to fly then your average aileron trainer as long as it is correctly set up. As far as you wanting to make an airplane heavier, that is just plain rediculous except in the case of a sailplane where ballast is used for windy days for better penetration ( Higher potential energy equalls more kinetic energy ) but this is onlt because it dosent have an engine in front.


Ok weight REDUCTION............... From the nose back. Tade the MA prop for a Vess prop. Not only lighter but better thrust to boot. The engine mounting screws are excessive. Not only too long but can be reduced to 3mm. The mount to firewall screws are most likely the same. The end of the mount could be trimmed 6-8 mm. Sand the inside of the cowl with 150 grit paper, a good 15 grams could be taken out. If you want to use a spinner, us a Dubro unit with the lightened backplate. You cut a hole in the firewall between the mounting holes. It offers no strength and is dead weight. The engine will have better air available to it and will run better anyways. Replace the trottle linkage with a smaller tube and a 1.5mm CF rod. A mini servo for throttle would cut a good 20 grams too. Move the rudder servo as far back as you can get it. It can be mounted on a couple 6mm rails. Replace the steel pull pull cables with nylon coated kevlar. Move the fuel tank to where your rudder servo is now. This will give you the CG shift you need. Get rid of the foam around the tank, it's dead weight. Gas engines run at a lower frequency and you will not have a fuel foaming issue. Use a peice of 3mm ply and make lots of cut outs for a tank mount. A single peice of velcro slightly smaller then the tank and a couple velcro straps with secure the tank. If the tank is bigger then 500ml then replace it to a smaller one. That 20 dosen't need alot of fuel. Moving the fuel tank will require you to cut out the canopy floor, more weight savings. Replacing the landing gear and wing tube with CF units will be a big drop but also the most expensive. The stock gear can be lightened. Drill 18mm holes between the mounting screws and yes the mounting screws are too big, replace them with 3mm hardware. The end of the gear where the axles are can be rounded off. If you have 2 wheel collars on each axle replace the inside one with a nylon spacer and the outter one with an aluminum collar. World models have the aluminum collars in 4mm. A few of the screws in the tail look a bit long, replace them with shorter ones. The rudder horn is heavy, get a pair of nylon control horns and replace. Forget the LIFE batteries, get lipo. A 1300 mah for RX and 900mah for ignition. That should be plenty for your 5 flights. You don't have digital servos so power draw is down. No need for big servos. Team Losi makes a great little 6V regulator the weighs next to nothing and is rated at 10 amps. You could easily drop 20-30 grams out of the fuse by sanding excess material. The inside edge of formers for example. If any of the servo or power wires are longer then they need to be, shorten them. I'm sure there is more but this is what I get out of the pics. Hopefully some of these suggestions will help you find even more.

Didn't see they were digitals but even though not very power hungry. I wouldn't call CF gear brittle. On a landing that would bend your aluminum gear will most likely delaminate a CF gear. The cood news is you can flow some thin CA into the delam, clamp it for a couple hors and it's as good as new.

I realize you may not want to go through all that effort but remember that with this hobby, you will only get out of it what you put into it. I intended this to not only be of benifit for you but others too so I went into a fair amount of detail. I do think that once you fly a really light airplane you will have more appriciation for how much better they fly. I expect alot out of my airplanes and put alot of effort into them, I realize that is not for everyone and as long as you have fun it's all good.

I love carbon gear, it's the only way to go for me. I find it much more resilient than aluminum. Get good gear from Graphtechrc.com, not the junk from the Chinese hobby stores. You should be able to get a set for $40 and save probably 80-100 grams.

grams beget ounces, ounces beget pounds.

Building a light airplane is an all encompassing exercise that starts with a critical design review before any wood is even cut (this includes covering selection). A traditional doped silk/silkspan or glassed coverings add considerable strength and rigidity to a structure, which CAN be fed back into structural material selections/sizings allowing for structural weight savings. Plastic coverings add nothing structurally and require stronger internal structure.

I've reworked a few ARF's and put them on diet plans for other people. An ARF diet plan is much harder than a scratch build diet plan because you'll wind up being forced to keep significant chunks of substandard structure and/or poorly selected wood.

In your case, with the gasser brick you've chosen to bolt on up front for an engine, the first place to look is at the engine itself. There's probably several ounces that could be shaved off that gas engine by a machinist (or with a Dremel if you have the patience). Every ounce off the engine is a few ounces less tail weight you need. Putting the engine on a diet plan is a win-win all the way around. Cast cylinder cooling fins and head fins are always good targets for shaving some thickness off. External case webbing can have lightening holes drilled in the corners. Casting flash can be ground off. If it has a steel prop nut/washer, substitute a lighter aluminum hub. Look at any spinner critically. Some of the TruTurns have extremely heavy (like about 4oz) solidish aluminum backplates. They can be riddled with lightening holes and rebalanced to save a couple of ounces.

I agree with the issue of putting good landing gears on the airplane but there is no way to get graphtech. It will cost twice the basic price to get it to India. I know the HK CF gears are quite good and cheap and thats why I got it. It was reputed to be unbreakable but the guys on my field told me not to use it. I will add it in once I get more used to the airplane and start doing 3D with it. Till then I would persiste with a bendable aluminium gear rather than a shatterable CF one. I think we should leave this for later

I am not desperate enough to try and mod my engine. Phoenix models are sturdily built which is why I picked this model. Remember, its a test rig before I open up my Funtana which is much more expensive

I am thinking of putting in a GP nylon spinner with lightened metal backplate (which I was using on my glow airplanes) simply to be able to use a starter. For the time being the cowl is off till I can get the engine broken in.

Ameyam

Oh Gawd...

You're dealing with a relative novice that has little experience, not an IMAC flyer.

His plane is over specs by a very small margin, he's never had to deal with 3D aerobatic planes, nor those that have inherent instabilities designed in for tumbling, snap, etc. purposes.

You CAN obtain very light Extras that loose many of the idiosyncracies of a normally loaded Extra, but that is beyond his scope. That is why he wants to STRENGTHEN things, as his landing skills are not up to it yet.

I've followed the OP through many such threads as he has progressed, answering his questions all along, and there have historically MANY MANY times such as this where he is focused on something too advanced for him to think about.

Your advice is like answering an overweight rider who asks about making his bike lighter to make things easier, by telling them about Carbon Fiber bike frames... it's a specious response in this case even though technically correct.... the bike rider needs to loose the weight not the bike.

Ameyan needs to fly more and stop fretting about a .2kg weight difference.

The context of these posts is important, something you've overlooked.

I agree, I need to fly more and think less right now. Alos, my landing skills are not yet upto the Extra's requirements, but they are getting there.

I think, I did conclude my thoughts with my yesterday's post. Today is a working Saturday and its been a hectic week, again I have not yer touched my sim. May not be flying tomorrow, need the rest. I will takeup the landing issue next week when Saturday is a holiday and then take it from there

Ameyam