[BUILD] Boeing C-17 Globemaster III

Started by yash10896, April 23, 2014, 01:19:00 AM

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K K Iyer

@yash10896
Did i mention sometime back that the servo arm on the aileron servos is too long?
Shorten it else too much movement on aileron!
(Further, as a general rule, the horn on the moving control surfaces should be as close to the hinge line as possible...)
Hope you got the epoxy for fibre glassing.
Can you also mention wing span, chord, weight and EDF/motor size?

yash10896

sir i will reduce it for sure i remember what you told me about that don't worry sir :)
and for horn sir i did research and found that for scale transport aircraft flying it required less throws so i think there will be low deflection angle on ailerons...
i got epoxy 2 bottle each of 130g for fibreglassing should 1 layer of 18g/m^2 will be enough or 2 layers...
i will go for 48g/m^2 for mid section of wing as it requires greater strength...

Specs :

fuselage: 1500mm
wing span:1405mm
naccelles: 74mm
edf's : 64mm

And here is some pro information specially made for you Iyer sir using 53 paper on ipad :)
Root Chord(A)-280mm
Tip Chord(B)-100mm
Sweep Distance(S)-300mm
Half span(Y)-650mm
% MAC Balance : 35%
Sweep Distance at MAC(C)-126.3mm
MAC : 204.2mm
MAC distance from root(d)-273.7mm
Balance Point at Root Chord(CG)-228.4mm

Regards
yash :hatsoff:


             
Challenges are what make life interesting and overcoming them is what makes life meaningful

K K Iyer

Haha.
Everything i need for an afternoon of headscratching!
Except wing area and estimated all up weight!

Remember to include the area of the wing intersected by the fuselage. Your 2 half spans of 650 don't add up to the total span of 1405.

I think you may have already come across this:

http://adamone.rchomepage.com/cg_calc.htm

Remember that all initial homebuilds have a risk of not flying. If you let that stop you, there would be no progress. So carry on regardless.

K K Iyer

1. Reason for horn position
2. Suggestion for cockpit interior!

yash10896

sir half span add upto approx 1300mm and rest is mid section hd foam which u forgot :D
and sir i saw that german guy paper build its fantastic but i can't compete with him on this :)
and thank you for that valuable information about hinges,horns and servo horns :) thats really helpful....
sir i will calculate wing area sorry for that and AUW will be 1-1.3kg that normal in these airliners build that i scrolled over on RCG and chris sir (demondriver) also told me that in airliner weight to thrust ratio can be 1:1 or 2:1 so no problem there as edf will produce 800-1000g of thrust each on 4s...

Regards
yash :hatsoff:
Challenges are what make life interesting and overcoming them is what makes life meaningful

yash10896

i have installed the electronic and wiring in fuselage now will work on other two naccelles which would be dummy ones...

Regards
yash :hatsoff:
Challenges are what make life interesting and overcoming them is what makes life meaningful

K K Iyer

Yash,
We MUST have an estimate of the wing loading.
You have to calculate the total wing area and weigh the entire project till now. Then estimate weight added by fibre glass and epoxy.
Flying depends on wing loading more than on power loading. Even gliders can fly!

If the wing loading is low, it can fly on very little power, say on thrust as low as 0.3-0.5 of the weight.
Remember it is not a helicopter that depends on thrust. It is an airplane that flies on its wings.

The speed reqd to fly safely depends on the stall speed, which depends on the wing loading.
Need to estimate the minimum speed reqd for safe takeoff and cruise (approx 2-2.5 times stall speed)

The issue is not whether your motors can lift the weight. Not looking for vertical takeoff.
The issue is what speed the wings need to lift the plane safely, and whether your motors can provide the necessary speed.

yash10896

the data is as follows:
Wing Area: 412 sq.in
Wing Loading:19.55 oz/sq.ft
Wing Cube Loading:11.6

i have less knowledge in this field some more elaboration would be helpful...

P.S my weighing machine (SF-400) died few weeks back don't know why so right now i have no means to calculate weight last time i calculated it was approx 560g of frame+retracts ordered today a new one till then i can only assume...
Challenges are what make life interesting and overcoming them is what makes life meaningful

K K Iyer

You may need 60-80kmph to lift off!

You also have to put straps around the mid point of each wing...
Hang it withthose straps...
Then put straps around the fuselage ahead of the LE and behind TE...
Then hang weights from them...
Equal to the AUW times 2,3,4,5...
To see how many Gs the wing and its spar can support, before breaking!
(This is what Shobhit17 sir was warning you about)

An airplane designer's life ain't easy, eh?

yash10896

sir don't scare me about these things please i didn't got you on those strap things but yeah i have seen tested model which fly with this kind of dimension maybe it risk but risk worth taken...
now its too late to step back may anything happen but i will get this thing in air thats my promise....

Regards
yash :hatsoff:
Challenges are what make life interesting and overcoming them is what makes life meaningful

K K Iyer

@yash10896
Those straps are just to check if your wings can take it.

I think your 2 EDFs will provide enough power. But your 4s may add too much weight.

Just take care of a few things:
1. Can the wings support 2-3 times the AUW?
2. Is the wing loading too high?
3. Is the CG right?

Do taxi tests first, gradually increase speed till you get lift off, then cut power.
After 3-4 attempts, you'll know the speed required to take off safely.
Expect to see video of success onSunday night!

yash10896

Thank you sir for that advice i will test it...
sorry i was little emotional on that reply cause i promised mummy that i will make this thing and it will fly she always supports me in this field as it is an expensive hobby and spending 10-15k on a single project in hole in pocket but they never opposed me on spending so much money they just want me to learn something that is different than others so i am very much passionate about this project i have been doing research from like aug'13 and going through around 50 build threads of airliners line by line gave me a lot of knowledge and different ways to get things done...
i have exchanged several pm's with sanjay sir,nithin sir and others too to assure that what i am choosing is tested...
It may happen that it could get crashed on maiden but it doesn't matter as far u have made something that is unusual and people are appreciating it so lets leave it to almighty about being it airworthy :)

Regards
yash :hatsoff:
Challenges are what make life interesting and overcoming them is what makes life meaningful

K K Iyer

Don't rush it.
Do it step by step.
Do the taxi tests first. Then you'll be safe.
Care:
Do not let anyone pressurise you.
Taxi as much as reqd. But take off only when you feel ready.

yash10896

okay sir i will keep it in mind...
taxi suggestion was also given by chris sir....
he has done several builds and all he says is just experiment :)

one question is their...
my batteries are coming through malaysia post surface mail it say on website for india it take 4-9 weeks that really worries me as it was shipped on 7th july and all till now it say send item abroad next location kochi so have anyone had this experience so far as till now all my parcel came through air mail this is something different...
Regards
yash :hatsoff:
Challenges are what make life interesting and overcoming them is what makes life meaningful

K K Iyer

Where are you on rcg?
I am on rcg but don't see all threads.
Also i don't see regularly.

I get my batteries from Adiboy whenever he drops in. So no problem.
I've told him to come to my house whenever he has time, and bring whatever he has.
Takes care of 90% of my reqmts.

Try him.
Nowadays he is half in Indore, half in Delhi.

yash10896

http://www.rcgroups.com/rc-airliners-commercial-cargo-troop-carrier-780/
less active on rcg as build is concerned...
please do check mike sir's 777-200LR build he has done marvelous job...
this is link to nibbio's sir thread of his globemaster back in 2005
http://www.rcgroups.com/forums/showthread.php?t=441400&highlight=nibbio+c+17

Regards
yash :hatsoff:
Challenges are what make life interesting and overcoming them is what makes life meaningful

yash10896

here is a snapshot of Rudi sir's comment on weight to thrust ratio of airliners...
Challenges are what make life interesting and overcoming them is what makes life meaningful

maahinberi

My recent parcel also came by surface mail via Kochi. I ordered on 9th May and received it on 18th July. So yeah, about 9 weeks.
Maahin Beri - Introduction and Hangar
Seagull Arising Star, Seagull Low Wing 40, AviSport (SPAD), Phoenix Scanner, VortexRC Speedster, Martian 220 Racing Quadcopter.

yash10896

@maahinberi sir thank you for the information so i think it will be here in september first week thats too bad.. all things are done and i just need batteries as edf is of 4s config and i don't have a 4s battery :(
Challenges are what make life interesting and overcoming them is what makes life meaningful

Aeroresurrect

Some real Globemasters C-17 have come to Delhi yesterday for induction to the IAF and Jaitley went to inspect it. I think you should have also gone for the inspection.

topalle

you should have bought one locally...
Amateur photographer ... DIY enthusiast ... Scratch Builder... Student-Innovator

yash10896

@topalle can u please provide me a genuine link for a lhs stocking it.... 5000mah ones
Challenges are what make life interesting and overcoming them is what makes life meaningful

rcrcnitesh

Maker | Aeromodeller | Teenager

topalle

Amateur photographer ... DIY enthusiast ... Scratch Builder... Student-Innovator

yash10896

i dont like wolfpack please only turnigy or haiyin high quality packs
and thats 5k what i have bought is of 2k more than double
Challenges are what make life interesting and overcoming them is what makes life meaningful