Hey Guys,

I crashed an extra .60-.90 size plane. I'm going to rebuild and try to go a little lighter in the process. When it was first built it weighed in right at 7lbs. It's got about 690inches of wing, making it about 23oz./sqin.


It was a little snappy.

This is how it adds up

Frame - 29oz
Landing gear/weels pants - 7.5oz
Wings - 10oz EACH!
Engine (saito 100) on the mounts - 23.5 oz.
Battery (1400mah nicad) - 4.5 oz
Servos - 5 @ 1.5oz each - 7.5oz
Tailwheel set up - 1oz
Wing tube - 2oz
Cowl - 4oz
Canopy/hatch - 5oz

Total without spinner,prop,prop nuts, misc screws for canopy hatch etc
( 6/8oz)

The wings seem VERY heavy. I had a fliton the same size and the wings were only 7oz each. Do you think I could lighten those somehow?

What size servo can I use for throttle with a saito 100... a micro??

I guess I could ditch the pants.

Aluminum gear to to carbon fiber? I don't know where I can find a set that fits

Battery, ... could I go to lion with reg? would it be lighter?

1.5 oz each servos... it calls for 80oz torque on ALL servos (except throttle). Are there any lighter that deliver?



Any advice or suggestions you have I would be greatly appreciate for.

thanks guys
Tim

First off, which model of Extra are we talking about here. Who makes it?

A couple suggestions for you off the top of my head. Does the plane have a wing tube? Graphtech makes carbon fiber wing tubes and Carbon gear that can shave off a few ounces. Also look into getting light axles and wheels. Ditch the wheel pants. As for servos you will have to do some research but I know for a fact you can use a good high quality mini servo for throttle. Like this one for example:

http://www3.towerhobbies.com/cgi-bin...?&I=LXVJU5&P=7 It weighs in at .6 oz, with metal gears and its digital.

I am not an expert on some of the structural components but the stuff I listed will shave off a few ounces and every little bit counts. Hope that helps. Good luck!

all TruBlu02 says, and use a 3A regulator with lipos, you can use 2s 700 mah (very light) reg at 6v means more speed and power for the servos, and you can charge at the field very quick, also it is possible to share lipos with rx and foamys as a foamy is much more stress for the lipo is good to test and check them that way.

I have used 5-6 gms servos for throttle with no problems at all for years, just put them away from the engine

anyway, In the landing gear is where you can save the most with CF

It's the aeroworks extra 260 60-90

They say it is 6-6.5 bls. Mine came in at 7lbs, and was built pretty light already.

Doing all this and STRIPPING the wheel pants, I think the most I'm going to come in at is 6 10. It's frustrating that they don't put real weights on their sites. are there any plane manufacturers you can trust their specs?

Can I use one of those hobby city HXT900 servos for the throttle, or do you think it would be too much for it? It's plastic gear super light, but may break from vibration?

The HXT900 are very light but to be honest you can only skimp so much on the throttle servo. I would use a good high quality servo for the throttle like the one I linked to in my earlier post. I've learned not to skimp on throttle servos. Trust me.....

I'm running a Hobbico CS-12MG on my throttle trouble-free. You could run the plastic gear version to save a bit of weight. I'm running dual-elevator servos (HS225MG's), that doesn't really help my weight...but it didn't hurt it by much. I was at exactly 7lbs with a 5-cell 1650mAh Rx pack, Saito 100, cowling, wheelpants, TruTurn spinner. I saved 3-4oz moving to a 1500mAh 2S lipo w/ reg.

I'm using 2s 1100 mah A123 batteries as rx pack in the same plane. It's around 3 oz and doesn't need any regulator. I typically use 60-100 mah per 10 min flight, so you should be able to get around 8 flights before recharging. And they can be fast charged in the field in 15 min if you need to. I'm using 2 Hitec 5625MG digital (rudder and elevator), 2 JR DS821 digital (ailerons), and 1 Hitec 85MG on throttle.

IMHO do not try too hard to make this plane lighter. It is an excellent pattern/IMAC plane but built too heavy for 3D.

So in the photo here http://www.aero-works.net/store/imag...60_large25.jpg

there are holes cut in the bottom panel just behind the firewall. My plane doesn't have them (just 2 servo holes in the back end, which aren't shown on this one...weird) do you think it would be worth cutting them out.

How much weight do you think you'd save?

what if I were to also cut a hole in the mount box like in the photo here. I've seen other planes that have had this done.

I agree. You can waste a lot of money trying to make a plane lighter - or you can just buy a lighter plane.

I am always going to extreme measures to make my aircraft light. here are some steps that work for me.
I always try to use carbon fiber wing tube and landing gear. Search http://www.graphtechrc.com/ I am sure they will have something you can use.
I refuse to fly an airplane with no spinner and prop just to save weight. I have my limits lol
I have cut lightening holes in the bottom of the wheel pants to save a few grahms
Also have run some caron fiber spinners, but I have not been able to find a spinner for the .40-1.20 size aircraft. Basicaly nothing from 2"- 3" So i have some success with electric spinners. They are a little lighter than the standard ones
Cut all bolts to lengh. For example, on motor mounts, cut any excess bolt that pertrudes past the blind nut. Do it for all bolts
I Strongly recomend you DO NOT try to shed weight from wings or tail surfaces. This is what takes the stress of all those violent 3d manuvers. I have had wings break in the air from blenders on my funtana 40
Remove as much material as you can "safely" from the hatch canopy area.
The axles that come with most ARF's are heavy. I use a bolt and 2 nuts and nylon spacer to get the wheel in correct position. no wheel collars. YOu can get this at hardware store. Just think light as you are making selection
For tail wheel I don't use wheel collar to retain wheel. come times I use small washer and solder. or CA a nylon retainer on it
You can also use kevlar cable for pull pull cable on rudder. I tie it in a knot directly on servo horn and use heat shrink to cover knots. and on the rudder end I do the same on the adjustable clevis. So adjustments for tension are made at rudder control horn.
Flighton makes some very light aluminum control horns or you can use the fiberglass control horns as with extreme flight
As far as electronics, Go with the lightest servos you can find that will give enough speed and torque.
For the fuel tank I do 3 line system. but one clunk. I just bend aluminum tubing down for fill and drain. And I dont use brass tubing. it is heavier

my suggestion is hs5245mg on ail and elev hs5645mg rudder And I have had good success with hs55 for throttle just make sure you use a soft mount for the throttle servo to minimise vibration. Two ways i do it is.
three layers of double stick tape and a zip tie
slice a piece of fuel tubing put it over the mounting tabs. run a srew through the top of the fuel tubing into the servo tab through the bottom of fuel tubing and into your wood.
use lipo batteries. for this size you can use 2cell 800mah and 6 volt mpi regulator
I get about 5 hard flights and I recharge. this pack will charge quickly at field

I have done a lot of other crazy things to save weight. like using plastic soda bottles for fuel tanks and nylon bolts but for me it is fun to try and learn new ways to make good planes fly better.

If you need any photos of some the things i described I can send.
Hope it helps

+1

Trpastor...I said this in my PM and I don't think I'll disagree with myself on this one. IMAC is what this plane is for me.

this is a pic of the vibration mount with fuel tubing

Hey guys - New report!

I don't have it all together yet, so I don't know how it flies, but I did put everything in, so I would know what wieght I'm looking at.

My plane came in originally at 6-15 to 7lbs.

To lighten it I did the following

Prop - from apc to wooden prop (1.5oz)
Lipo/regulator from 6v nicad pack (2oz)
NO wheelpants (2oz total)
Dubro Tailwheel (.5oz)
Cut holes under fuel tank, in top and bottom of firewall (3/4oz?)
Micro Servo for throttle (1oz)
Replace Axel/4wheel collars with bolt nut (.5oz)

These are all approximate.

My NEW weight is................................................ ..6lbs 5oz!

That should take my wing loading from 23.3oz/sqin to 21oz!!!

I'm not sure yet what effect this will have on the plane, but I'm excited to see.

I don't have it all 100% ready, so that could go up slightly (foam under battery and zip ties, but I think it will stay pretty close. Just wanted to let you guys know. I'll keep you updated
Tim

Good job!!! Was there any place in the hatch area you could save some weight? See how the wood prop works. I would also recomend still trying the apc prop. even though it may be slightly heavier I have seen tremendous performance gains when comparing wood props to apc props on these smaller planes. even at slow stalled speeds.

By the way. just by weight and wing area comparison of this model to a similar sized model I owned. so I i am sure it will 3d excellent!

Thanks! I did'nt really see any areas I could save weight in the hatch. It's 4.5oz I think, but it's fiberglass and has ligheting holes cut in it already. I'm afraid if I go more it will break from vibration alone

here's their photos online of it
http://www.aero-works.net/store/imag...60_large25.jpg

and the canopy/hatch itself
http://www.aero-works.net/store/imag...60_large22.jpg

any ideas? I'm only using the left side of the middle hatch area to secure my reciever. I could cut out a hole on the right (since my battery is in back)

I'm looking forward to flying it and seeing if it will 3d better now
Thanks for your help again.