RC India

Hi All.

I just started building this model. I need some help in reinforcing the structure.

The attached diagram shows the reinforcement placements and I am planning to use Sheekh Kabab Skewers extensively. in fact for the wing leading edges (A) & (B), I have created long spars by cementing 2 skewers end to end. The joint is strong and the whole spar flexes well. Since they will be embedded in a furrow and covered with epoxy and set to cure overnight, I think this will provide sufficient strength and resilience against crashes.

These skewers are made of some kind of dense composite material (doesn't seem like bamboo, but I could be mistaken) which is very flexible yet strong. Takes a good deal of effort to snap or cut them. Does anyone have any experience with these type of skewers?

Any advice will be appreciated.

Regards,

VC

so After Tomhe's F-22, now F-18 Hornet!! great going VC!

Where did you get the Kabab skewers ? even I would like to preserve my CF stock for later...

Hi Ujj!

I just build them, never get around to flying them. You guys are the actual flyers, I am just a theoretical @$$****!

You want some kebab skewers? Let me have your address. I picked up mine from a shop that deals in party supplies like depron plates and stuff.

Cheers mate!

VC

Administrator Sir, my apologies for the self deprecating description. I am just a wee bit frustrated with life today. Pardon me. :bow:

Hi VC I have used the bamboo sticks. They are better than the Carbon fiber one for short spans (like up to 30cm) I have tried joining them by tying two ends with thread and gluing with epoxy. They work great. :thumbsup:
Here I have 2 sizes available here. One is aound 2 to 3 mm dia and the other about 5 to 6mm dia. I have used the small ones in all my foamies. :)

bmanoj2 :salute: - Thanks Buddy! This gives me a lot of reassurance.

Here are some pics of the build in progress...........

Looks Neat..What glue are you using to fix the bamboo sticks (I can’t see any foam safe ca)? From the picture I think you have joined them too ??  I am not sure about the diameter of the sticks you are using but 3 mm will be great. If you feel that its more flexible just apply a thin layer of epoxy and allow it to cure before using them. But this will increase the weight of the model slightly. All the best and be little careful while launching the model as the propeller will be behind your hand. :)

The sticks are less than 3mm and I have joined them with epoxy and standard CA glue. The groove that I will have to create along the fuselage will be filled with epoxy and these sticks will rest in them. 24 hours of curing should make them rock solid. BTW, I  don't have Foam Safe CA glue. Expecting it next week, courtesy Anam.

Why only pusher jets ? ;)

There is a FW 190 D similarly cut out and ready for assembly. It has a full profile fuselage. I plan to start on that after I finish this.

The model now weighs 125 grams. Estimated AUW is below 350 grams.

This is what I plan to use:

EMAX CF2805 Outrunner Brushless Motor
6 X 4P prop
ESC - DYS 18 Amps
3S 1300 mAh LiPo
9gm Servo X 2

Experts please advise if my combo seems sound, I am looking for a moderately fast flyer - not aiming for crazy bursts of speed or fancy aerobatics to start with.

Cheers!

VC

hi VC grt plan yaar!!!

i am going to copy this one for my next build!!!

Ashish

Should I send it to you, or do you already have it?

Which EMAX CF2805 are you using ? 1600kV or 2840kv ?
6x4 would be fine for 1600kv. But just a little bit overkill for 2840. in later case try 6x3 or 5x4 and see the load on Watt Meter.

18Amp is okay if its not heating up much on static test. 25Amp would be safer option.

Thanks UJJwaana for the tip. I am expecting the  2840 Kv from Dinil and was planning to use that. Will now change the prop to 6X3.

VC,
i just sayed 1st diagram, is it enough? can u pls provide dimension as well!!

thanks
Ashish

Hi Ashish, I have sent you a PM. Pl check.

PM not yet received !!! :-(

PM received, replied!!

Ashish, pl check your mail.

hey VC any update on this.

are u able to put motor and fly it????

i do have FC 2805 2840Kv motor with me and i think ur also planning to use same motor. pls let me know the combination result!!!!!

i am planning to build eurofighter from the plans u sent me. if this motor is good then i will also use same one and will start building!!!!

Ashish

Ashish, will keep you posted on this. I plan to install the powerplant over this weekend. Wish me luck!

All the best!!!!

let us know the good news!!! and some video as well!!!

Ashish

Construction of the model is now complete, with the exception of the hinges for the 4 control surfaces. AUW is 340 grams.

Final configuration as follows:

EMax CF 2805 (2840 Kv)
6X4 Pusher Prop
2s 1200 mAh LiPo
ESC 25 A (I can also use an 18 A) as suggested here:

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5353

This combination should give me a thrust of approximately 413 grams at a current draw of 12 Amps.

Typical newbie question - 400 + grams thrust for an AUW of 340 grams - what kind of performance are we talking about here? Sedate, Moderate or Blazing fast?  ???

Please advise urgently, as I want to finish the model today and maiden her immediately.

Thanks!

hey VC,

thats grt  :salute:!! would like to see it flying!!!!

abt performance i think it will give sedate flying!!!! i am using same motor on modified Phantom super 210, it has got 31" wingspan, havnt chk AUW!!! but it is giveing sedate/moderate flight chk my youtube video!! i am using 5x4 prop on this one!!!!
http://www.youtube.com/watch?v=vg5apqP4b1o

thougth it is mentioned 400+ thrust but i think it will not give that much!!!

but lets see hw it performs on ur plane!!!!!

Ashish

Thanks! Working on it now. Will keep you posted.

After speaking with Ashish last evening, and reading the following pages,

http://www.rcsmart.com.my/webshaper/store/viewProd.asp?pkProductItem=795

http://www.rcsmart.com.my/webshaper/store/viewProd.asp?pkProductItem=797

I feel that the 2805 motor, will not be able to power this model. I am therefore switching to the heavier 2812. It says that the 2805 is suited for models between 200 to 300 grams weight only. The 2812, on the other hand, is suitable for weights upto 600 grams. Should end up with a moderately fast aircraft with this new powerplant - all other factors remaining constant.

Experts please advise.

Regards.

HI VC,
2812 is good motor, currently i am using it for my 30" wing Yak 54

http://www.rcindia.org/electric-planes/mini-yak-54-made-from-biofoam!!/

even i ordered 2822 for this plane so that i can do lots of 3D!! ofcourse once i learn it!!!

but it is lower Kv motor and will need bigger prop around 7"-8"! if possible, for speed try using high kv (around 3000Kv) and small prop!!!!!! if the slot in the plane allows bigger prop then go for it!!!!!

why dont u try something like this, just thought!!!!
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8143

i ordered this for my Blade CP pro Heli, installed it!!! but in future if i get a chance will try to use it for something like ur plane!!!!

Ashish

Dear VC,

Your Plan's slot and space for prop is available max for 6" only. Hence I would suggest you to stick with 2805 motor only. If the KV ratting of the motor is 2840KV as intimated by you earlier, then You should use only a 5x4 for a 3S Lipo 11.1V with 30 Amps ESC. On watt meter it will easily clip 23 Amps.  If you are planning to use a 6x4 prop then use only max a 2s lipo 7.4V with 25 Amps ESC.

you will not be able to use a 2822 or 2812 as they are lower KV rating motor and will require a prop of 8" or more which will not be able to be fitted in your model. If you use a 6" Prop it will not give desired thrust.

You will have a moderately agile aircraft 3s 5x4 prop on a 2840 KV motor. You should be able to achieve 60-80MPH easily

Thanks Col Sir for explaining this aspect. Will stick to the original 2805 now. Unfortunately, will be able to use only a 25 A ESC, as I don't have anything higher than that. Suppose I stick to the original config :

EMax CF 2805 (2840 Kv)
6X4 Pusher Prop
2s 1200 mAh LiPo
ESC 25 A or 18 A

What will be the resulting flight characteristics of the model?

Cheers!

Even though I use a 2200 KV on 3s with 30/40 Amps ESC, I do not to fly full throttle since aircraft becomes highly responsive and flight time is also reduced. I fly only in half throttle even in half throttle the aircraft is fast. I think with 2s you will have reasonably fast aircraft with a good response. Best wishes and waiting for your video.

"Best wishes and waiting for your video."

You have more faith in me than I have in myself. You lead and I shall follow. I will wait for the MiG 29 Profile flyer video Sir and then I will go and crash the F 18 and post it here!

Dear VC some more reference for you on your Emax 2805 various voltages and prop combination and thrust thereof.

http://www.headsuprc.com/servlet/the-1409/EMAX-CF2805-Outrunner-Brushless/Detail

I think you should keep AUW less than 400 to have a vertical and loop capability.

Mig 29 I had lot of trim and control problem because it was highly responsive. Now it is flying beautifully with 70% dual rate and 70 % exponential.

I will record and post video at the earliest opportunity.

Commenced work on a sukhoi 37 now I think we can finish up together ;)  ;D.

i never used prop bigger than 5", but data seems impressive at 7".

VC, go ahead giv it a shot!!!!! all the best!!!
and dont forget a video!!!!

VC patrao,
when are you goin to maiden fly her ?

patrao=boss in konkani...