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Author Topic: Lilienthal glider  (Read 2924 times)
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Pete Fardell
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« Reply #75 on: November 03, 2013, 07:49:47 AM »

Oh okay, it's a bit of foam rubber on a box.
The weight in the base, by the way, is a tin of Heinz beans wrapped in bubble wrap. And yes, that is a paper clip for the towline ring (and it works a lot better than the bent wire loop I lost!)
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TimH
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« Reply #76 on: November 03, 2013, 10:39:23 AM »

Video of Pete launching Otto at Clayton Green.

http://youtu.be/Iq4l1R8WO6M
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Pete Fardell
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« Reply #77 on: November 03, 2013, 11:58:23 AM »

Thanks Tim! And so long as everyone watches the glider they won't notice me bumbling into the flight path of Reg's Arado. Over the course of the afternoon I also managed to entangle at least three people in my towline, despite trying to launch in the less busy moments. So far I've not actually tripped anyone over and luckily Reg's model wasn't damaged, but after nearly squashing Andy S's Prefect last week I'm beginning to wonder if I need some training in indoor glider procedure before I cause a major mishap! Or perhaps just a small injection to boost my overall gorm levels.
The rather exagerated dihedral shows up clearly on that video. The wing broke at the hub joints on almost the first test flight of the day and I think I must have let the tissue's tension pull the wings up a bit when I reglued them. Even so, the glide isn't too bad on that clip. Probably quite scale-like really, as you said at the time. Hopefully it will be shallower now that I've reconfigured it though. Apparently the real glider dropped about a foot for every three it went forward, which I think is a glide angle of about 18.5 degrees? Sounds quite steep to me, but I don't know how it compares with more modern gliders.
« Last Edit: November 03, 2013, 12:25:34 PM by Pete Fardell » Logged
Yak 52
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« Reply #78 on: November 03, 2013, 12:39:59 PM »

Nice video Pete and Tim. Made me jump as I hadn't quite cottoned on to what I was looking at before it hopped out of the launcher  Grin

the design of the launcher is very complex and it utilises a lot of intricate and  high tech engineering principles...

...The weight in the base, by the way, is a tin of Heinz beans wrapped in bubble wrap.

Engineering Principle #1: if it's got to be heavy make it useful. Edible ballast - genius  Cool



Apparently the real glider dropped about a foot for every three it went forward, which I think is a glide angle of about 18.5 degrees? Sounds quite steep to me, but I don't know how it compares with more modern gliders.

That's pretty awful by modern standards Undecided but Otto still deserves kudos for a glide ratio of 3:1 in an era when most 'aircraft' achieve 0:1  Roll Eyes My Hutter H17 was called the H17 because it's glide ratio was 17:1  Wink The model won't be that good of course due to good old Mr Osborne Reynolds.
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Pete Fardell
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« Reply #79 on: November 03, 2013, 01:00:20 PM »

I think his last flight possibly had a glide ratio 0:1! But Otto certainly knew what he was doing. He made nearly 2500 flights over his career and clocked 5 HOURS of air time! (I've been boring everyone with that fact lately.)
So many successful flights suggests a very good level of control, but he eventually met his demise after stalling his biplane glider. The trouble was that though the extra wing gave him more lift it also gave him less control  and he couldn't shift his weight far or quickly enough to bring the nose down in a gust. What a genius though! FIVE HOURS- I still can't get over that!
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« Reply #80 on: November 03, 2013, 01:17:07 PM »

That is very impressive! I hope the model gets to 5 hours too Pete  Grin

Speaking of which: are we looking for 15 seconds to qualify in Flying Only? (Maybe this is not confirmed yet) I think it'll be quite a challenge - even more so than in open rubber.
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Pete Fardell
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« Reply #81 on: November 03, 2013, 01:33:01 PM »

I was talking to Andy Sephton about this at Shawbury and I think the news might be good. He said he's considering waiving the minimum time rule and just letting the judges mark according to the general characteristics of the flight (which will naturally take the time into consideration). Even if the rule stays, he said it will include the tow up time. (So in my case I can just run around with it on its thread for the first 14 seconds and then release it to glide down in 2! Grin)
I'm sure he'll let us all know what's been decided in good time. The clear message I'm getting is that priority this year is to encourage people to enter and to just explore the possibilities of indoor scale gliding, so I'm sure the rules will allow most of us to compete if we've made something for it.
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« Reply #82 on: November 03, 2013, 02:13:28 PM »

Nice launcher Pete .... does it have to be Heinz beans? .... or is that Otto's friend?  Roll Eyes

I did notice the collision ... sorry.

I'm going for a hand launch .... I'm working on a pair of 20 foot 'Jazz hands'  Wink

Considering you had not done much towing, you are catching up very quickly in experience.
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Pete Fardell
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« Reply #83 on: November 03, 2013, 03:24:00 PM »

Thanks Russ. I've been getting lots of guidance and advice along the way though. For instance Tim suggested yesterday that by slowing down and not just stopping dead at the end of my run, I could avoid the tendency of the glider to be pulled into a dive as it releases. This seemed to work. I suppose the knack of towing and releasing must vary quite a bit from model to model doesn't it? I expect it's something you get a feel for. It's certainly quite a satisfying way of launching a model when it works I think.
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« Reply #84 on: November 03, 2013, 03:30:08 PM »

Brilliant stuff Pete. I assume the tail is now rigid?
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Pete Fardell
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« Reply #85 on: November 03, 2013, 03:37:01 PM »

More or less. The whole boom is still quite flexible but I added a thin piece of aluminium to the existing overly bendy wire hinge. So I can still make adjustments if I really need to; the difference is it now doesn't move unless I deliberately bend it. I thought I might need the hinge to add a bit of rudder, but so far it hasn't flown quite far enough to reach a wall even when it stays straight!
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yagua
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« Reply #86 on: November 04, 2013, 03:18:59 PM »

hello Pete!
lovely videos!! ¿do you have, by chance, any picture of the hinge at the tail?? or some schematics? my hands are feeling the itching!!!  Wink
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Pete Fardell
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« Reply #87 on: November 04, 2013, 05:10:49 PM »

Here's a close-up of the tail, with the bit of aluminium stuck over the wobbly hinge (which was a bendy bag-tie wrapped in tissue). I wouldn't really recommend copying this part though, as I'm not at all convinced that it needed a hinge at all. The tailplane is more or less set flat now, which stopped the stall. I think I may be able to get a better glide by gradually taking off nose weight, but the problem with fine trimming is I risk stalling it again and the model often breaks if Otto lands too hard on his feet. I need a field of long grass....indoors. The break point is usually where the cross piece joins the wing hub-thingies (technical term!). This is an area I'd rethink a bit if I made another one. Just using harder balsa for the cross piece would probably have been enough.
I'm not sure what I can do in the way of 'schemantics' as draughtsmanship is not my strong point, but any particular aspects which are unclear from previous posts, let me know and I'll certainly try to explain! Really hope you do make another. Or how about his biplane? I'm half inclined to do a Pilcher Hawk.
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Re: Lilienthal glider
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yagua
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« Reply #88 on: November 04, 2013, 06:00:04 PM »

So you hinge the entire tail. No schematics needed. that picture tells a lot!
biplane... mmmmm... I haven´t thought about it!  Roll Eyes
by the way: found this page with pics of diferent lilientahl models. http://www.theaerodrome.com/forum/models/13404-lilienthal-models.html
kind of small pictures, but the craftmanship is undeniable!!! Shocked
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Pete Fardell
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« Reply #89 on: November 13, 2013, 06:19:21 PM »

he eventually met his demise after stalling his biplane glider
I was wrong here. Not sure where I got that from, but his last flight was in one of his standard monoplane gliders.
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SP250
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« Reply #90 on: November 28, 2013, 12:25:58 PM »

Here you go Pete - some more flying masterpieces to keep your Lilienthal glider company.
http://www.mymodernmet.com/profiles/blogs/luigi-prina-flying-model-ships

Regards John
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« Reply #91 on: November 28, 2013, 01:53:21 PM »

Marvelous! ... they have gone into my favourite pages  Smiley
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« Reply #92 on: November 28, 2013, 05:05:22 PM »

Peter,
Earlier in this thread you were concerned about getting in he way of other flyers and their machines: don't give it another thought.  It is a long established fact that Steam gives way to Sail.  You are flying a Sailplane and the others are messing with their powered vehicles so enjoy yourself and tell the others you will sue if they get in your way.  (Don't try that with Top man Tom of course. he's a Tiger when roused and he's bigger than you.)

John
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John Barker UK - Will be missed by all that knew him.
Pete Fardell
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« Reply #93 on: November 28, 2013, 07:02:25 PM »

Those Luigi Prina creations are just marvellous. Thanks for the link!

John, it's not so much the sailplane which is a problem as the string; basically an invisible tripwire in a hall full of people who's eyesight is perhaps not quite as good as it used to be! Thanks for the support though.
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