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Old 04-23-2013, 05:01 PM   #1
karolenaz
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Default Need information about rc planes.

Hello guys,


I'm new here and i want to build an rc plane. Past 5 years i was buildind free flight planes like : F1C I want glider tug like this: http://www.outerzone.co.uk/plan_details.asp?ID=789 (because my friend flyies rc gliders ) What should i change to this model to make it rc
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Old 04-23-2013, 06:30 PM   #2
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Lots to change... better to start out with a set of plans intended for RC.

Also you need to determine the size of the tow-plane needed for the sailplane to be towed.

It is easier to do a cradle launch than a tow launch. A cradle launch you build a set of pylons to support the sailplane above the "tow-plane" CG locations should be directly on top of each other. Space between wings should be at least 75% of the larger chord. Alignment should be appx 1 to 3 deg negative wing incidence of the sailplane's wing relative to the tow-plane's wing.

Cradle launches the tow-plane pilot does all of the control until launch.
There are ways to have both control the release but generally just the tow-plane will have control of that.

Tow-line launches the sailplane pilot has to actively ensure the sailplane does not get out of line with the tow-plane which can cause both models to go out of control.
Both the tow-plane and the sailplane need servo actuated releases. Hopefully one of the two will figure out its time to cut loose before both models are destroyed.
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Old 04-23-2013, 06:55 PM   #3
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Maybe can you write what to change? Because i want to build this model since i was a child. It's my favourite.( also i can make like a normal plane not tow-plane )

And also i will start a build thread here

thank you for info
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Old 04-23-2013, 07:14 PM   #4
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Basically you have to do the obvious stuff like adding movable control surfaces (ailerons, elevator, rudder). Plus if you want electric power you have to adapt the motor mount and install some sort of access hatch for the battery.

It's the detail of how you do those things that is the challenging part, and you need to figure out the details yourself if you chose to do a conversion. If you have been building freeflight for a few years that shouldn't be too difficult.

At 36" span it looks a bit small for a glider tug unless your friend fly small gliders. On a model that size and type you also need to be quite careful about weight.
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Old 04-23-2013, 07:29 PM   #5
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and how about Airfoil? Is it good for wings and for rudder? And i think i will use a balsa wood for formers i think ply is bit heavy
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Old 04-23-2013, 07:48 PM   #6
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Originally Posted by karolenaz View Post
and how about Airfoil? Is it good for wings and for rudder? And i think i will use a balsa wood for formers i think ply is bit heavy
just use the same airfoils and construction as the plan indicates. If it flew ok freeflight then it will fly ok with RC in.. And yes, at that size it will all be almost all balsa, not ply.
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Old 04-23-2013, 08:13 PM   #7
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Originally Posted by JetPlaneFlyer View Post
just use the same airfoils and construction as the plan indicates. If it flew ok freeflight then it will fly ok with RC in.. And yes, at that size it will all be almost all balsa, not ply.
Thank you very much for useful information
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Old 04-23-2013, 08:32 PM   #8
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But the structure will be wrong for the power you will be putting in it... and mounting the equipment to tow or carry the sailplane.

FF has very different structural requirements than RC. The FF model never pulls more than a couple of G + and any "beefiness" will be aimed at keeping the plane intact on landing. Your RC version will easily exceed 10G and you would be surprised how easily you can exceed 40G! The average FF model can not withstand a simple loop.

And you have given no indication of the size sailplane you will be towing.
Changing scale would require even more extensive changes.

Again... You would be far better off (especially for your first RC model) to start with something already in a proven RC configuration.

Then you'll have to learn how to operate the RC model. You'll probably go through 2 aircraft just training to be ready to start towing.

I have been building with balsa... starting with FF rubber power... for 47 years.

************

http://www.icare-rc.com/wilga.htm

The Wilga is not the problem... It can be done.

How big do you need? (minimum 50% of the span of what you will tow) Your tow-plane must be large and light enough that with the engine/motor system and RC equipment it stalls close to the same speed as the sailplane.

How much power to tow the sailplane? (minimum 50% more than needed to fly the sport-aerobatic version of the same plane)

Its just not as simple as you think.
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Old 04-23-2013, 09:24 PM   #9
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The structure totally depends on how you want to fly it. This is intended to be a slow flying STOL scale model, i don't see why it needs to be built for extreme 10g aerobatics?

If you beef it up it will end up heavy which will make it fast flying and potentially tricky. Built with modern lightweight RC, LiPo and brushless you should be able to do it just about as light as the original freeflight design. IMHO (based on only 45 years of RC and freeflight but several own designed published plans and kits) there is often no reason to beef up anything. In fact for RC the airframe should have an easier time because landings can be more controlled. take a look at Pat Trittle plans if you want some inspiration of how freeflight type designs can make great RC models.

Also bear in mind that 'beefing up' adds weight which increases the loading on the structure and can be self defeating. I think it was Anthony Fokker who said something along the lines of "to increase strength add lightness"

Bottom line is you build the model to suit the intended flight envelope. If you want a fast aerobatic model build it heavy and strong. If you want a lightweight model to fly 'floaty' and slow, much like the original freeflight design, then build it as per original plan.

Steve
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Old 04-23-2013, 09:50 PM   #10
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Extreme is relative...

The average sport aerobatic model exceeds 10 G on a regular basis. Pattern competition models exceed 40 G. 3D aerobatics can exceed 100G.

A simple banked, coordinated (low stress) turn you will hit 2G.

Then you are sticknig in the extra weight of the RC system and E-power capable of towing an appx 2 meter (max) sailplane. Suddenly that model is carrying 2X to 4X its expected weight in level flight. Now do that banked turn and you may be watching the wing fold.

Start with a plan designed for the load.

Do it right...
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Old 04-25-2013, 02:56 PM   #11
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Hello guys,


I found another wilga plan for rc its 55". I reduced plan by 41,25 inch span and i think i'll be able to fly gliders to 2metres span
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Old 04-26-2013, 05:44 PM   #12
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So i'm going to start it I want to ask about the airfoil is it good or i sahoul change to clark-y? (airfoil w4)





Wing span will be 55"

Karolis
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Old 04-26-2013, 06:21 PM   #13
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The Wilga's airfoil is an update from the Clark Y...

Build as per the plan set for the RC model.

I would also recommend keeping the original scale of the plans. The 1/2 span of towplane vs sailplane is a LIMIT, not a goal.
Towplane being larger means the sailplane is less likely to "take control" if the sailplane pilot goofs.
You'll also be able to have the towplane carry a larger motor and battery (e-power) or engine and still have a light enough model so the stall speed is similar to that of the sailplane.
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Old 04-26-2013, 07:41 PM   #14
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So one more question to go How about wing construction? Maybe i can change that strong carpet thread to balsa? and how about the longerone can i use pine? and the ribs are from 1/16" should i use 2 mm balsa?

thanks for info





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Old 04-26-2013, 07:46 PM   #15
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Plans


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Old 04-26-2013, 08:00 PM   #16
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You could change the "strong thread" to kevlar or "Spiderwire" fish line. Either is an improvement over the thread.

You could also put in balsa but I would have to study the plans to determine size required. Thread/kevflar/spiderwire will be easier... and lighter.

The thread being called for says its for resistance to twisting.

You could get away with deleting the threads if using a true silk and "Dope" covering (if you don't warp the wing doing the covering) by putting the silk on at a bias (threads running diagonaly instead of in line with the spars and ribs)
But this covering method is a LOT of work...

*************

2mm is very close to 1/16 inch so that would be fine.

Replacing the hard balsa spars with Pine is Ok... Slightly stronger and not much more weight.

But don't go overboard trying to make it stronger.

I bought a model that was at ready to cover stage once and found that they had replaced 3/8 sq balsa spars with some wood that was so dense it wouldn't float in water. Similar "upgrades" throughout... what was supposed to be a 5 lb airplane came out at 12 lbs without fuel.
Fortunately the plane had a reputation as a heavy lifter...
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Old 04-26-2013, 09:24 PM   #17
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Originally Posted by karolenaz View Post
Plans
I did not know when i sent you the plans your were in another country . I have the plans in metric if you would like them better ? joe
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Old 04-26-2013, 09:43 PM   #18
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The original plans came from here along with that nice DH-84 dragon. They are in metrict on this site ,enjoy. joe http://mysite.verizon.net/milkyway99/id3.html
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Old 04-27-2013, 07:33 AM   #19
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No i think these 55" will be ok because i want to tug bigger gliders

But that wilga 55" too on the site. The aircraft 39.3" (998 mm.) length



Karolis
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Old 04-27-2013, 02:56 PM   #20
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I would think about replacing the thread with 1mm carbon rod. You could sandwich your main spar with 1mm carbon sheet on both sides and using the carbon sheet for the shear webbing too. That way you can get incredible wing strength with almost no weight increase at all.
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Old 04-27-2013, 05:00 PM   #21
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Originally Posted by Rockin Robbins View Post
I would think about replacing the thread with 1mm carbon rod. You could sandwich your main spar with 1mm carbon sheet on both sides and using the carbon sheet for the shear webbing too. That way you can get incredible wing strength with almost no weight increase at all.
If the design structure is good... the carbon being added is an expensive waste of effort.

Capping the top of the top spar and the bottom of the bottom spar with CF would add a huge amount of strength but that stuff is expensive.
He's already talking about moving to pine instead of balsa which is a strength upgrade at small weight penalty. (and CHEAP)

Similarly the CF rod replacing the thread is a $50.00 solution to a $0.25 problem. Kevlar thread would be about $2.00 but the benefit is less chance of rot than an organic fibre.
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Old 04-27-2013, 05:27 PM   #22
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Originally Posted by JetPlaneFlyer View Post
The structure totally depends on how you want to fly it. This is intended to be a slow flying STOL scale model, i don't see why it needs to be built for extreme 10g aerobatics?

If you beef it up it will end up heavy which will make it fast flying and potentially tricky. Built with modern lightweight RC, LiPo and brushless you should be able to do it just about as light as the original freeflight design. IMHO (based on only 45 years of RC and freeflight but several own designed published plans and kits) there is often no reason to beef up anything. In fact for RC the airframe should have an easier time because landings can be more controlled. take a look at Pat Trittle plans if you want some inspiration of how freeflight type designs can make great RC models.

Also bear in mind that 'beefing up' adds weight which increases the loading on the structure and can be self defeating. I think it was Anthony Fokker who said something along the lines of "to increase strength add lightness"

Bottom line is you build the model to suit the intended flight envelope. If you want a fast aerobatic model build it heavy and strong. If you want a lightweight model to fly 'floaty' and slow, much like the original freeflight design, then build it as per original plan.

Steve
I tend to agree with the above approach....especially since it may become something more than a "tug" in the future.

"the carbon being added is an expensive waste of effort."

Expense, a little yes.....but a wasted effort....no way any modification that provides long term structural integrity should be considered a "wasted effort".....

"less chance of rot than an organic fibre."...........are we talking fruits and vegetables or the long term environmental impacts combining "carbon" Kevlar material with wood will have, over, say a decade of conditions......lol......

AMA 928214
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Old 04-27-2013, 07:09 PM   #23
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Originally Posted by pizzano View Post
I tend to agree with the above approach....especially since it may become something more than a "tug" in the future.

"the carbon being added is an expensive waste of effort."

Expense, a little yes.....but a wasted effort....no way any modification that provides long term structural integrity should be considered a "wasted effort".....

"less chance of rot than an organic fibre."...........are we talking fruits and vegetables or the long term environmental impacts combining "carbon" Kevlar material with wood will have, over, say a decade of conditions......lol......
absolutely zero value post... thanks
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Old 04-27-2013, 08:25 PM   #24
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It's all a matter of prospective observation Professor Huber (not the "Ernie" Fred E. Huber of AMA fame)....after all, a little light hearted humor may go a long way after observing fhhuber threads posted on nearly 90% of all those related to anything RC here....lol. (yes, the vast experince is evident, + 40 years I believe)

I thought one who has (over the years) bounced around the many other forums, (rcuniverse, rcgroups, RCDiscuss, defunct AMA, Air-RC (I believe you met ARBO), ModelAirplaneNews), and a few others.... might appeciate a friendly jab......

Now, back on topic: How is using the "graphite" Kevlar in combination with Pine/Balsa going to degrade (rot) the sufaces it's applied to....?....How much time and what environmental conditions would contribute to the degradation.....inquiring minds wonder?

AMA 928214
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Old 04-27-2013, 08:42 PM   #25
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reported your personal trolling attack post... thanks

And you might try READING sometime..

I said Kevlar was less likely to rot than organic thread.
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