GliderIreland - Ireland RC Forum - Flying Model forum in Ireland
Techniques => How to... => Topic started by: skyhawk newbie on October 27, 2010, 11:56:14 AM
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As a newbie.......... :oops:
Just wondering what you guys do to reinforce your glider wings ....
If you fit a carbon fiber spar how long it is and what diameter ...
do you use a flat or round spar...
where about in the wing do you fit it ...
Regards Sean
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As a newbie.......... :oops:
Just wondering what you guys do to reinforce your glider wings ....
If you fit a carbon fiber spar how long it is and what diameter ...
do you use a flat or round spar...
where about in the wing do you fit it ...
Regards Sean
I think the answer to that would have to be "It depends...."
It's very difficult to give a general answer.
Why are you reinforcing the wing? Is it a repair, to handle extra power due to your new power system or are you trying to make it crash proof?
Crash proofness is pretty much impossible to achieve with anything but very small planes or by making the plane from flexible material (typically EPP). Often the extra weight and stiffness added by reinforcements has the opposite of the planned effect and just makes the plane more likely to break. Weight can also make it harder to fly so a crash is more likely too!
For a wing with a single spar, that spar will normally be at or near the thickest part of the wing to maximise the stiffness it provides. This also puts it near the point on the wing chord (an imaginary line from the leading edge to trailing edge) where the result of the combined aerodynamic forces appears to act which means aerodynamic loads in flight are less likely to cause twisting of the wing around the spar.
The length will depend entirly on the purpose and the wing you're adding the spar to.
A tube provides torsional stiffness (resistance to twisting) as well as resisting bending loads. A strip positioned vertically will be good for preventing vertical bending (which is what you get from lift) but not very good for bending forward and back or torsion. If these aren't needed because it's already stiff enough then a strip is a good option.
Aidan
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As Aidan says, need more info.
Size of wing, length and mean chord.
What the wing is made of. Type of construction, (open rib, Foam).
What type of flying was it designed for and what do you want it to do now that needs more strength?
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The SkyHawk glider that I've got..
http://cgi.ebay.com/New-4Ch-RTF-RC-EP-Aerobatic-TW742-SkyHawk-Glider-Plane_W0QQitemZ290326804731QQcategoryZ19164QQcmdZViewItemQQ_trksidZp3286.m7QQ_trkparmsZalgo%3DLVI%26itu%3DUCI%26otn%3D3%26po%3DLVI%26ps%3D63%26clkid%3D5078401181636134857
The wing is 115.5cm or 45 1/2 " in length, chord is 21.5cm or 8 1/2"
and made of foam......
The wing has a very narrow channel where a wooden connector rod (about 4" long ) sits inside a plastic housing. I would like to place a carbon fiber rod there, but I am not sure whether to make it go all the way to the end of the wing or just 12" or so. The wing is basicly screwed together with a square-ish piece of plastic that holds the ailaron servo in place,
I'm thinking of removing the plastic connector and epoxy a aluminum plate instead, as I'm going to fit twin servos for the ailaron..
Then lay a piece of carbonfiber rod, about 1ft long along where the wooden rod was on the wing and epoxy the carbon fiber rod in and then run some tape over it.....
Would this work.....
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They say a picture paints a thousand words Sean :D
You might like to get your camera out and post a few pictures of what you want to do….?
(Just going back to what Aidan said, you can’t make them crash proof without making them much heavier and more difficult to fly! :!: )
K.
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Yeah.. Will defo get some photos up,so you'll know what I mean...
mite take a few days....
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Here a few photos of the new wing....
This photp shows how the wing looks , when put together ,
with the connector rod and the black crappy thin plastic that holds the servo in place ( no servo fited yet ) as I'm gona fit 2 servos into each wing half..
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/TW-742%20SkyHawk%20Glider/skyhawktw-742wing002.jpg)
This shows the wooden connector...
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/TW-742%20SkyHawk%20Glider/skyhawktw-742wing003.jpg)
This is where it sits in the other wing...
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/TW-742%20SkyHawk%20Glider/skyhawktw-742wing004.jpg)
See where the wooden connector is...I wana remove that and fit a carbon fiber spar there instead...But how long ??? 12 " or the whole length of the wing...Where the servo mounting sits,I'll fit a thin Alloy plate...
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/TW-742%20SkyHawk%20Glider/skyhawktw-742wing001.jpg)
Regards
Sean
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Okay Sean,…….firstly let me tell you that those strange black & white circular signs are where the centre of gravity (balance point) should be.
That wooden connector is know as the ‘wing joiner’.
Now a couple of questions: :?
Why do you want to replace the wooden wing joiner?
Although it may have been a “slip of the tongue” but you said that you want to fit 2 servos in each wing half. (4 servos in all in the wing?) Did you mean that? :?: (Are you looking to produce what’s called a full house wing, with flaps and ailerons.)
Sorry about this but until we know what you’re trying to achieve there could be one of a dozen different answers to you questions.
Keith
(You’re on a steep learning curve, and doing very well! :clap: )
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a.
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Okay Sean,…….firstly let me tell you that those strange black & white circular signs are where the centre of gravity (balance point) should be.
That wooden connector is know as the ‘wing joiner’.
Now a couple of questions: :?
Why do you want to replace the wooden wing joiner?
Although it may have been a “slip of the tongue” but you said that you want to fit 2 servos in each wing half. (4 servos in all in the wing?) Did you mean that? :?: (Are you looking to produce what’s called a full house wing, with flaps and ailerons.)
Sorry about this but until we know what you’re trying to achieve there could be one of a dozen different answers to you questions.
Keith
(You’re on a steep learning curve, and doing very well! :clap: )
Well if your gona do it , do it right the fist time...
Hi Keith
The reason I wana replace the wooden wing joiner and black crappy plastic ,
is because I've read ( on a USofA Flying forum there was old review (2007) of the SkyHawk Glider )
that the wing will flex or snap in the middle where the join is,in tight aerobatic turns....
So I'd like to sort this out before I get that far.....
Sorry "slip of the tongue"
what I ment was fit 2 servos for the ailerons..
one for each side...
Regards Sean
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I note that you are reading from an old review (2007) and I’m thinking that the model you have now might have been modified (improved) since then.
Looking at the set up you have, I can’t imagine that wooden wing joiner snapping in flight. I suspect what was more likely to have happened is that either the wing joiner, (in the right hand wing) or the wing joiner socket, (in the left hand wing) became un-glued and allowed the wing to “Butterfly” in a tight turn or when coming out of a steep dive.
Provided the existing wing joiner in your model is glued in properly I’d have thought it would be strong enough.
Whilst I take your point of wanting to “solve the problem before it becomes a problem :clap: ” I think I’d be inclined to fly it as it is. After all, it’s likely to be a little while before you’re pulling high G‘s.
May be some other forum members would have some thoughts on this matter.
K.
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Here a few photos of what I'm planing to do...
Replace the foam ailerons with some balsa one's I've made
they'll be stronger as I wana fit servos for each aileron,
fit a thin (1mm)alloy plate where the black plastic one was...
Apoxy 2 hollow 4mm carbon fiber rod's front and rear of the servos..
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmods001-1.jpg)
As for the fuse...
Replace the thin metal push rods ( that bend javascript:emoticon(':cry:') ) with some Gold-n-Rod,These will prevent tail pushrods from bending. When the pushrod bends, it does not break, but it stops controlling.
Will allso add a wire guide positioned midway between the fuse pushrod slots and the tail.....
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmods002-1.jpg)
What do you think ?????
Not bad for a newbie....
:lol:
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Anybody......
I'm not gona do anything to the wing
untill I get a go ahead....
yeah you could do that or
No don't do it......
I've all ready wrecked one wing ,
by doing my own DIY mod :oops: ...
and not asking enough questions first :!:
So now I'm down to
3x fuse and 2x wings off a TW-742 SkyHawk...
Sean
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Quote from RC Groups.com about the TW-742 SkyHawk.....
I actually have a little experience with these. My dad bought one and I put it together, trimmed out and test flew it for a bit before handing it over to him. I actually thought it went pretty well for a cheapy. Not fast, and didn't climb ridiculously fast but was quite ok. flew for about 12-14 min in still air with supplied NiMh battery and a couple of 25+ min thermal flights in not particularly strong lift. I was happy enough with it that I got one for a friend who wanted a cheap intro into RC gliding. He's had a blast with it, and it's proved a lot tougher than you'd imagine. We haven't DS'ed it yet.
The first mods you should do are make a better wing joiner (ply is good) and glue the halves together, reinforce the TE where the rubber bands go (to save the foam) a bit of thin plastic or something will do. A few strips of BiDi TESA tape on the bottom of the wing and around the LE (cover the BiDi with coloured tape to keep UV at bay) Replace all the servos with HXT500/900, the originals are embarrasing. Ditch the center aileron servo and fit a seperate servo for each aileron. Make sure the pushrod ends are fitted properly. It'll fly fine with just the center servo but seperate ones are a lot nicer. About 45 min work so far
See how it goes, then think about upgrading the power system.
It slope soars just fine. I don't think you'll be too disappointed for the money it cost you.
Good luck,
simon... "Quote"
What is BiDi TESA..Can you get it in Ireland ??
Sean
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Joining the wing halves to form a single wing piece sounds a good idea. Replacing the servos also seems advisable, most RTF models have cheap twitchy servos supplied.
I’d stick with a single aileron servo, as fitting two has no advantage that I can see and only adds weight and complexity. :evil:
Keep an eye on the models’ All Up Weight, (AUW) Sean. The more weight, ….the harder to fly the model will become. I believe 600grms is the designed AUW for your plane.
You will also need a supply of rubber bands for the wing…………they are always breaking.
Afraid I’ve never heard of BiDi Tesa, :?: I suspect it could be a type of fibre reinforcing tape………..but I’m not sure.
Good Luck,
Keith
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Cheers Keith...
So Apoxying the wing halfs together with the Carbon Fiber rod's is OK...
The only reseaon I wana add the 2 aileron servos is because every time
I've had a hard landing ( lots,so much so the 1st skyhawk is now in bits)
I'm breaking the servo in the middle of the wing,haveing servo's (9g each) mounted on each wing half will stop this happening......
Sean
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Epoxy-ing the wing halves together would seem a good idea.
Before you stick them together assemble them on a table and look at the wing from the front, (or rear) you may well notice that they have ‘dihedral’. That means that the wing tips are higher than the middle of the wing. Or to put it another way, when viewed from the front or back the wing has a very flat V shape.
I tell you this so that when you glue the two halves together you must make sure that the wing maintains that dihedral angle. If you glue the wing together without it, the plane will be far harder to fly. :roll:
Personally I wouldn’t bother with the carbon rods Sean, just glue the ‘male’ wing joiner into the ‘female’ (socket) at the same time as you’re gluing the wing halves together. To fit the carbon tubes you’ll first have to cut out a grove in the wing, then place glue in it followed by the tube. This will all add weight.
Like-wise an extra aileron servo will add weight and in the world of flight, weight is the enemy! :evil: :evil: :evil:
The more your model weighs the faster it will have to travel through the air to over come the effect of gravity, and fly. (Just like the airliner that takes you on your holidays. Before it can leave the runway it has to go faster and faster.)
Let’s think about landing your plane………….
To reduce the risk of damage at touch down the idea is to get the plane to fly as slowly as possible before it actually touches the ground. That’s pretty obvious isn’t it.
But your plane won’t be able to fly slowly, because it’ll be caring extra weight. …….so it’ll have to maintain a higher air speed. Savvy?
If you try to slow it down too much before putting it onto the ground it’s wing will “Stall” and the plane will just fall and hit the ground like a stone. (Ask me how I know :oops: )
What I’m trying to say is….”Keep your plane as light as possible!”
Oh, putting two aileron servos won’t stop either of them getting damaged.. But you will have the problem of how to fit them without either leaving them sticking out into the airflow creating turbulence and drag, or countersinking them into the foam of the wing, weakening the wing structure even more.
Having said all this, Model flying is only a hobby. So there is no law that say’s you can’t do what you want to…..and see what happens!!
Keith
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Well Keith,
This is what I've done today...
Glued some velcro onto the fuse..
50mm extensoin servo lead for aileron servo..
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmods003.jpg)
I didn't fit the Gold-n Rod's in the end as I found them
too flexable for my liking.
but did fit a guild for the tail rods to run through
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmods004.jpg)
I went ahead and joined the wing halfs together,
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmods006.jpg)
Carbon Fiber Rods fitted and apoxeed into place...
didn't do the twin servos as said it would only
weaken the wing and add extra weight
Velcro on LE/TE of wing
hopefully this will stop the wing moving some what on heavy landings
( will still be useing rubber bands as well)
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmods005.jpg)
I've still to fit the balsa aileron.....But that can wait till another day ...
Sean
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Heres a Vid I've just put up on Youtube of my Up-Grades so far....
http://www.youtube.com/watch?v=3e4Pno8hyWI
Sean
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Did some more Mods..
Fitted the Gold-n-Rods to the tail..
Mounted them in some balsa wood,to hold in place and
this will stop them flexing at the front..
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmod004.jpg)
Glued into place inside the fuse..
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmod007.jpg)
Mite remove the push rod guild as I don't think it looks right now with the Gold-n-Rods
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmod005.jpg)
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmod006.jpg)
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmod008.jpg)
(http://i591.photobucket.com/albums/ss354/seanmcgrath48/wingmod009-1.jpg)
Sean