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Author Topic: What is needed to fly a simple glider starting from zero?  (Read 553 times)
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OOS, January 2019
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« on: July 21, 2018, 11:21:38 AM »

Before I ask for advice perhaps I should mention my already extensive experience of RC.
About 1970 I bought some stuff (a peculiar thing for me to do!) from a chap who was giving up modelling. It turned out to be some early RC equipment. The transmitter was a metal box about as big as a packet of cream crackers that had a button at one end. Another smaller box was an actuator which had a lever on top which could be attached to the rudder so that if the button on the transmitter was pressed once the rudder moved one way and if the button was pressed twice it went the other way. I fancied trying slope soaring so I built a simple stick and tissue glider  I told a chap where I worked that it might stay in the air for several minutes if the weather was good so he insisted on coming with me to try it.  I launched and he moved a bit for a better view and said carry on I’ve got a watch on you. I flew around for a bit and asked if that was enough and he said ‘No, try for a quarter of an hour’.  I kept flying here and there and he kept saying ‘keep on’ and eventually, ‘that’s an hour, you can come down now’.  My first landing. If I tried down the slope she went faster and faster and if I tried up the slope she lost speed too quickly. Remember this was with button presses. I finally landed at an hour and a quarter.  A long flight but my main recollection is: ‘That was boring’
All I remember here is doing no aeromodelling for several years because the family were clamouring for me to build a sailing dinghy and race it on the recently opened Erwood reservoir.  This I did until my son thought I was too big?,heavy?,old?, to crew for him anymore.
I don’t know how I tumbled back into modelling but fortunately it was into a club named BATS which was full of expert RC glider flyers. My good friend Ralph Sparrow, well known on ‘Hippocket’ was one, George Stringwell, who wrote the book and had a monthly column was another. I think two more were column writers for different magazines and I believe one was editor of one of the early mags for electric RC. I must not forget Bill Dulson who was the leader in modern glider materials and design.  All won or placed high in competitions.
I built a transmitter from a kit which sorta worked. I built a stick and tissue glider for it which glided nice and sedately on the slopes or from a bungee and I usually managed to land back in the field I took off from. However, I found it was quite boring and I realised that it was because I was not competing.  Then the truth struck me: you can’t compete in modern glider flying with a lightweight ‘stick and tissue model’. Then I realized that I would need a lot of money for new materials and probably a lot more time than I have to learn how to use them effectively so I said ‘good bye’ to RC and returned to my first love, rubber duration models.
However circumstances alter cases. I cannot do long retrieves (say anything over 20 yards) nowadays. So my rubber flying is limited to Indoors. However I do see some beautiful scale models flown indoors with the help of radio.  Could I do that to widen my interests?
Next. I am only a few hundred yards from the start of Baildon Moor.  There are several roads across the moor and also parking areas for cars. I am told that people are seen with models in these areas. If I build a glider I assume that if I added an electric motor I could get it up to flying height without the use of a towline or Bungee.
As you can see I am a complete ignoramus on RC matters; so much so that I don’t even know what I need to know. Let me put consideration of Indoor radio on the back burner and just think of a glider with electric motor. Electricity probably means batteries and that makes me think of chargers. Then the word channel is often used which presumably relates to how many things one wants to control. I guess on the glider I would want to switch the motor on and off, move the rudder to turn and move the elevator to trim. Three channels?  I made my first buy from ebay a few days ago, (bags for the kitchen bin!). The sale was so simple and quick that I wondered if they also did aeromodelling stuff so I typed in ‘RC equipment’ and got an offer of a six channel transmitter and receiver for £32.  Is that a bargain or something to be avoided at all costs?
I am sorry for the long ramble; I admit I was carried away reliving the past. I can’t face editing it now and you will probably enjoy poking fun at a, so-called, aeromodeller who doesn’t know anything about the most popular branch of the hobby..  However I really will value any suggestions, recommendations, advice and casual comments.  I am under pressure at this end. My delightful Daughter who is also my No.1 carer knows that we English brag about how little we spend on modelling equipment says just get on with it, you CAN afford it now. When your grandson comes to stay (about twice a year) he won’t want to see how to wind a rubber motor, he’ll want to control a model with some 21st. century technology.

John Barker UK - Will be missed by all that knew him.
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« Reply #1 on: July 21, 2018, 12:44:38 PM »

Hello John
Others will help on choice of model, although I do know there is a vast number of RTF electric gliders available. But your comment 'it was boring' struck a chord. I've built three RC models over the years; a glider, a Junior 60 and a scale model. The latter was a nice single channel Blackburn monoplane with a Mills 75. I took it down to a local field and must have made 20 - 30 flights; launch, potter around, land at my feet, do it again. I never flew it again and turned it back to FF. It makes absolutely no sense to fly it FF, but there you are.
Good luck with it
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« Reply #2 on: July 21, 2018, 01:11:10 PM »

What better place to start than with an RC conversion of your iconic Lulu II?  It is listed in Outerzone as https://outerzone.co.uk/plan_details.asp?ID=1082
You will note on the plan site that our mutual friend George Stringwell built an electric RC version with success. George is still flying in France, mostly RC electric RC vintage models. He is very active on RCGroups under the Vintage RC section. He goes under the title Sundancer and just celebrated his 77th birthday.

Your  Lulu Baby is also on Outerzone as https://outerzone.co.uk/plan_details.asp?ID=3643   This with a 10 gram electric motor and  lightweight RC gear would be perfect for indoors.

John O'Sullivan
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« Reply #3 on: July 26, 2018, 11:03:37 PM »

If you want to catch thermals, you may want a somewhat larger model than a Lulu II. If they're interested in building, I usually suggest my glider flying students build an Olympic II. It has nice handling and floats well. I imagine there's something similar that's British, though I guess if you're scratch building, that doesn't matter much. Make sure to cover at least the inner panels of the wing with something at least as stiff in shear as Monokote, because the wing relies on the covering for torsional stiffness. I don't know how the various traditional coverings compare to Monokote. In the case of woven fabric, applying it on a bias should make it much stiffer in torsion, but I don't know how that affects the covering job. The only traditional covering I've used is tissue, which is probably a bit fragile for a 2 meter or larger glider. The Olympic II has a slow airfoil. This may be handy when learning, as if you freeze on the controls in a dive, you can take longer to unfreeze before it breaks. On the other hand, as you get more experience, a bit more of a speed range may be handy for getting back upwind or scooting out of sink. Free flight, high lift, "under-cambered" airfoils aren't really an advantage in RC, though I do have a few minutes' stick time on another pilots Super Sinbad, which used the NACA 6409. It was slow, but the wind was very light so it wasn't a problem.

The equipment that comes with a 2 meter Radian would be more than sufficient to launch an Olympic II. So that might be appropriate as a reference for what types and sizes of equipment you need. Perhaps you could acquire a crashed Radian to get that equipment as a package. Un-crashed Radians fly quite well, but you don't get to build them. BTW, I'm sure you could fly rubber powered models of medium size (22-28 inches?)  outside with the equipment that comes with the little UMX Radian. Or inside, if they're slightly larger and quite light.

You may want to make the underside of the wings of anything you build a dark color, so you can see them at high altitudes.

Anyway, here's a suggested list of equipment:
-2 or 3 servos for rudder, elevator and, optionally, spoilers (spoilers are nice to have if you get in a strong thermal or just for landing more precisely) Suggest you use the elevator actively instead of just for trim. Otherwise, the model will dive in turns.
-maybe a switch harness so that you aren't just using the main power plug as a switch
-3 cell, 1200 to 1400 lipo is the most commonly used battery for a 2 meter or light 100 inch glider, but there are other options. I'm partial to Lithium iron phosphate batteries, because I think they're safer. The battery voltage, motor ratings, and prop size all interact.
-Charger for the lipo. This doesn't have to be fancy.
-transmitter and, preferably, rechargeable batteries and an appropriate charger. A wall wart is just fine if it's the appropriate type and you're patient.
-folding prop and spinner, or an assembly of both as in the Radian
-ESC aka electronic speed control. Generally this will have a BEC, which means you can use it to run the receiver as well.

suggested additional equipment:
-voltmeter, a cheap one will probably do.
-a 12 V battery that is not your car's to run the charger. Nice to know that your car's starter battery still has a full charge at the end of the day! I'm guessing the 7 Ah gel cells that are commonly sold will do fine. I use a 33 Ah battery that someone gave me for free.

More on transmitters: Here in the USA, the old 72 mHz transmitters are still fine, and are very inexpensive used. The associated receivers are generally good if dual conversion. You'll need the correct crystals for each unless your receiver is synthesized and can be set for your transmitter. The transmitter needs a crystal too unless it's "dial a crash". Crystals are often brand specific. Then you have to make sure that the tx and rx are both positive shift or both negative shift, except that some receivers don't care about that. I've had very good luck with the Airtronics Vanguard radios, but that's getting really old now. It seems to me that you're on some other frequencies, but perhaps the old gear you have over there is the same except for the frequency. Most flyers, around here at least, have moved onto the 2.4 gHz gear and probably think I'm a Luddite. A nice feature of the 2.4 stuff is that it tends to be smart enough to keep out of the way of other 2.4 equipment. If you go this route, avoid the DX5e transmitter, which seemed to be weaker and prone to range problems, both in my experience and in others.

With 2.4 receivers, pay attention to antenna installation, as you may have problems if those two little whiskers aren't perpendicular to each other. The older gear had single antennas, and they were pretty good if fully extended and not right next to something metal. Sometimes a lot of carbon fiber next to the antenna could be a problem, but not always.

Thermal hunting can be quite entertaining. If memory serves, you have quite a bit of experience with free flight gliders, so that ought to help, but when you have control of the model it's a whole other game. I've found slope soaring rather boring, though I imagine it's quite a bit more fun if racing or doing aerobatics.

You might consider practicing with CRRCsim, which you can find on the web. There's a Yahoo Group, a wiki, and I don't know what else. It's free, all you have to pay for is the cable to adapt your transmitter to your computer. I haven't tried a lot of sims, but it seemed to me when I tried it that it behaved a lot more like a real glider than some others I've seen. In any case, crashes in the simulator are much less expensive! Flying students have told me that simulators can be helpful, but I have to admit that I don't use them much, nor was much available when I was learning.

It's hard to find, but the Old Buzzard's Soaring Book, by Dave Thornburg  is very good on how to catch thermals. As an experienced free flight guy, you may already know much of what it says, but not all. Unfortunately, it's hard to find. It was based on some columns in Model Builder, in case you can find those instead. Having met Mr. Thornburg at the US Nats, I wish he'd written a book on how to be tremendously energetic and helpful.

I hope that's useful. I ought to be doing something else, so I'll stop now.
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