Does anyone know the wing area of the CA models 24% Extra 300L? If you don't, can you give me a way to measure it or give me an exemple for similar size plane please?

I measured mine at 752 square inches without the fuse and it seems very low

thanks!

(Root + Tip ) x 1/2 wingspan = Wing area

Hello Viper,
Can you give me more details please? The tip of the wing is 8''5/16'' long and the side of the Aluminium tube is 15''1/8'' long.

If the span is 73'' does it mean :
(8''5/16'' +15''1/8'' )*73''/2=855 square inches area?
And what about the fuse and stab?

Scoubidou,

That is correct, think of it this way, it's easier to calculate the area of a rectangle,: width * length.

If you draw out your wings it becomes clearer:



tip + root adds up to one side of the rectangle, 1/2 the total wingspan the other.

The fuse and tail area are normally ignored in the wing area calculation, as they only contribute to directional stability, not lift.
It's a different story with Jets though, for the F-16 for example, the fuselage can generate up to 30% of the total lift amount.

Hope this helps, if not, don't hesitate to ask.
Best Regards,
Gert

Thanks for your help Viper, it's more clear now!

Here is why I needed it: A small plane like that should have a wing loading (oz/pi2) ratio between 24-27 oz/pi2 for maximum performance (a friend told me that). With 855 in2 area and 11 lbs weight (MVVS1.6 on the nose!) , I would have 29oz/pi2 ratio a little bit too heavy...

If I can reduce the flying weight to 10 lbs max, I would have a 26.9 oz/pi2 ratio and better flight performance for aerobatics

That's why glow engine is better on that plane but I want to put a gaz engine in mine to fly a lot, at low cost To get it, I will have to reduce the plane's weight with an heavier engine like gaz.

Have you already done some similar calculations before? If yes, what would be the wing loading or the oz/pi2 ratio on a similar plane?
I am just a backyard engineer trying to understand how planes fly!!

Mine weighs in at 11.6lbs...but its terribly tail heavy. I flew 3 sorties today and the plane was tuff to land. Inverteds were climbing etc. I have a saito 180 in the nose with a heavy APC16x7 prop (odd size, did not get 17x6) and a metal spinner. I also have 2 hitec 5945 digital servos at the aft of the fuse as twin elevator servos. These weigh only 56gms each..so abt 112gms (0.25lbs) at the rear extra that could have been at the CG...

I hooked up the plane on the CG balancer at the recommended CG point...over the tube...and the plane needed abt 650 gms (1.4 lbs) of nose weight right at the firewall to balance decently...still slightly tail heavy, but now with fuel in the tanks...it would be better. If I go ahead and add this 1.4lbs..the total weight of the plane goes to a high of 13 lbs....tooooo high for a plane of this category...the plane will hover but I doubt if it will harrier and do fancy 3d stuff.

To add to this, mine has been built by a professional...

I wonder what others are getting on theirs...

Hello Ragz!!
I have checked with Don from planesplus and the wing area is 889.92sq inches on the 24CA Extra.

I am glad to see that you have landed safety your bird!
Damn....13lbs with 890sqin area give you 208oz/6.18sqft=33oz/sqft ratio and really too heavy man! You will have to land at full speed!!!! Please remove that twin servos for the elevator and put only one!
I am gonna put the rudder+elevator servos over the wing tube instead of putting them in the tail and adding dead weight in the nose.

CA model suggest 10lbs on the web site. Based on this, we would have 160oz/6.18=25.9oz/sqft, that's correct for aerobatic performance.

11.6lbs give you 185.6oz/6.18=30oz/sqft and my opinion, that's the maximum acceptable limit with the right CG on that plane.

What engine mount did you use?
I plan to put an MVVS1.6 but to save the maximum weight on it by:
1) replace the existing landing gear by carbon fiber TNT
2) micro servo for throttle
3) 10oz tank
4) light Robart wheels
5) Light engine mount
6) I am gonna put many holes (1'' diameter) on the wings and stab to save weight.
7) put all servos in the middle of the fuse if required
8) Only one servo for the elevator
8) put helium in the wheels...

Keeps contact guy!
Scou

The saito 180 weighs 880gms...if u put anything lighter up front , it will be more tail heavy. I was using micro hitec hs81 for the throttle...but i changed that to a normal futaba 148 as the tail was heavy. The best idea is to reduce wt. in the tail by making holes...let me know how you make those holes...saving wt. up front wont be much help, unless u reduce tail wt.

Moreove, I will get an MK bellcrank and move the tail elevator servos upfront. The rudder servo is already under the tube.

Hi Ragz
I have got 1 picture showing how to reduce weight with the stab, fuse and wing by doing big holes. PLease send me your email if you want it, and please attach it to this tread for other guys.

Which software can I use to attach it to this tread??


Scoubidou
danyboy_636hotmail.com

Scoubidou,

Just click the 'edit' button under your last post,
on the bottom use the 'Attach file' function to browse to the photo on your hard disk.

hope that helps,
Regards,
Gert

It does not work.
Scou

Scou, my email is [email protected]

here are the pics of the 24% with holes in the tail area

The most important thing is to do it carrefully, at the right place and we can save some oz, 8oz=1"lbs!!
Scou

How much do you think will be saved with this mod? 1lbs? Any mods for the fuse? How are you doing the elevator servo? single or twin? or pull pull?

I estimate 1/2lbs the maximum weight saving with holes only (16 holes of 0.5oz=8oz). I have found a CF landing gear at TNT (Edge CLG114) for 3.6 oz instead of the supplied in the kit 7.23oz. I am going to use one servo for the elevator , one pull pull servo for the rudder and use the lightest wheel possible. No idea presently except 'Robart' wheels. I started another tread for engine mount and some guys gave me good ideas. My problem is to put an MVVS1.6 gas without loosing aerobatic performance. The only way to get it, will be to save weight. Let me know if you have any others ideas!!

I'll we be very happy at 10.5lbs dry weight. I am not sure if I going to do all the holes like the picture. I don'T want to breake my wings after my first SNAP!!
Scou.

references:
http://www.rcuniverse.com/showthread...417&forumid=37
http://www.tntlandinggear.com/store/...nding_gear.htm]

Hi, saving total weight is possible by using more expensive carbon equipment. The biggest Q is how much can u save on the tail? or the area behind the tube...If that area is as heavy as it is now, you will HAVE to add dead nose weight, and that will make the expensive equipment useless. Hence I keep wondering how you can reduce the wt. off that heavy tail...what about slimming down the turtle deck in some way? Punch holes in the turtle deck too? The holes are a good idea, as long as they dont compromise the structural integrity of the plane.

Finally, how are you setting up the single elevator servo? Carbon push rod with bellcrank?

I will need 2 battery pack 4.8v (1500mam ignition+1100mamp servos) in my plane. I going to try to find out the lightest in the market. Those battery pack will add some weight in the nose.
Let me know if you know some light battery manufacturers.

Mayur and you gave me nice idea with the MK bellcrank for elevator. I have not decided yet if I will use a standard metal pushrod between the servo and the elevator horn or the bellcrank system. Perhaps the MK bellcrank is better for aerobatic performance??? I dont' like carbon rod for elevator. it's not enough strong. Probably the metal-wood-metal rods with MK bellcrank.
http://www.gatorrc.com/

It is impossible for me to estimate the future CG position because i am building it now. I am confident being able to move my CG to the right place by:
1)installing the engine first and after,
2)install the servo and finnally
3) the battery pack to get the CG to the wing tube.

Punch holes in the turtle deck too? The holes are a good idea, as long as they dont compromise the structural integrity of the plane.
I agree with your comments.

This plane requires a few engineering to build it right, that's why i like it!

I'll let you know


Scou

I might as well chime in here....

My 24% is right at 11lbs dry, with a 3 lb 1.6 gasser up front. I used very light weight covering(the same stuff used on park fliers) to keep the overall weight down. STILL, it balances 1/2" behind the wing tube. I'm ready to test fly, but don't want to add any dead weight up front. I wonder what the safe CG range is on this plane??

I detect a small design problem with this plane also. Seems to be designed for a 3 lb+ engine up front, yet they spec it out as a 9-10 lb plane. I suppose no one would by it if they said 11-12 Mine is built dead stock in the tail.

Everyone's I've heard of seems to be coming out tail heavy.
CA really needs to move the wing tube location rearward about 1/2 to 1" in order for this thing to balance correct with a light glow motor. It was designed for elevator servo's in the tail right??

IMO The wing looks short in proportion to the fuse length. adding 4-5" to each tip would get the wing loading back down in the mid 20's

Kevin

Ragz,

Your ailerons and rudder look very small in your picture with the cutouts...are you not following the directions

Kevin

Nice pic Tipover. Good luck for the maiden flight!
I have the same comment on the wing area. I have measured it at 855sqin wing area without fuse and CA say 890sqin area??

It's is really short for 73'' wing. Forget the low speed landing except with flaperons!!

1) Where did you put the servos and battery pack (ignition+receiver)?
2) Did you use the MK bellcrank system for elevator?
3) Which wheels did you use?
4) Which engine mount?
Thanks to share the info with us. I will be the last one to built it and every time will be better, if we work all together to improve it!!
Scou.

My wingspan measures 72". Forgot to mention, I have no wheel pants, They might add another 4oz??

2 Standard elevator servo's in tail, 6-32 control horns, what use to be 6-32 Rocket City clevis's. Push-rods are Hanger 9 titanium. Looks like a heavy setup, but lighter than 4-40 threaded metal rods. Lightweight Dubro tail wheel bracket with homemade wire setup.
Kavan wheels would be lightest, not sure what I have...

Kevin

Motor is Zenoah G26 modified to electronic ign. No mount needed. 16 oz tank(overkill) 500ma ign batt, up front lower right.
1400ma rec pack at wing tube. Throttle servo in front of pull-pull rudder. Those two could be moved forward for a very small gain in forward CG. Hate to move the receiver stuff any closer to the ignition system.

I think CA literally scaled this 24% down from their 27% A good example of reverse engineering gone haywire

SCOU, if you haven't mounted your wing tube in the fuse, it may be worth relocating rearward. Looks like there's enough wood there to do the job. I tend to like a tailheavy setup, so with some luck, my 1/2" back CG may be ok. Time will tell...

Kevin

I love that huge RUDDER!!

You can save 3oz by replacing the main landing gear and 1 oz, if you put a micro servo for throttle and if you search more, you will remove 2 or 3 oz to get 8oz (1/2lbs) weight saving, where that plane begins to glide!!

SCOU, if you haven't mounted your wing tube in the fuse, it may be worth relocating rearward. Looks like there's enough wood there to do the job..

I haven't monted yet, but what advantage is to install that tube rearward?? It will be more tail heavy??
Scou

Scou,

How do you intend to NOT use a bellcrank and still not install the elevator servos in the tail? Are you planning a pull pull elevator setup too? If you dont use a bellcrank, then wont the long push rods to the rear be awkward? Reagarding the battery, I have a 650ma AAA Nimh battery pack that I use in my fun flys..i dont know if you are using digital servos, as they will draw more current and im not sure if the AAA will do the job. I use twin nicads.

Kevin,
Those pics are not mine, Dan sent it to me. Even My 24% weighed in at arnd 11lbs dry with a saito 180 in it. Check out this thread from post #27 onwards..you will know exactly my problem.

http://www.rcuniverse.com/showthread...14#post1354992]