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Author Topic: Bungee Launch 36" Gliders  (Read 37367 times)
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skyrocket
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« Reply #75 on: August 21, 2013, 08:22:22 AM »

AND it's a real cutey...rules?
!. Any glider up to 36" span or set a date limit to say 1956
2.No weight limit.
3. 25 foot of 1/8" rubber plus 75 feet of 30 to 50 lb string
4. 3 x 2 min. max's then 1 min. increments
5. No auto surfaces other than auto-rudder
....the only things I find that  I can't come to grips with is weight limit and modern materials...you can't penalize a flyer for his/her ability to not build light (or heavy) but I wouldn't want to see this winding up (?) the way FAI did...and where would we be without Epoxy and cyno?...and would a Sinbad fly well against a more modern style glider? 
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PeeTee
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« Reply #76 on: August 21, 2013, 09:38:35 AM »

Over here in England there are two distinct classes - the Peterboro' club one where anything goes provided the model is 36" span or less and launched from the prescribed bungee, and the SAM1066/35 vintage and classic class.

The SAM rules for vintage are as follows:

Up to 36” Vintage Glider - Hi start (bungee launch)
1.   Any model designed as a glider with wingspan up to and including 36”, from the Vintage period as described above may be flown (A vintage model must be built in accordance with a design that was first flown, published or kitted prior to 1st January 1951, (January 1951 issues of magazines are accepted as published in 1950).
2.   Maximum towline length 30 metres comprising 7.5 metres (unstretched) rubber strip up to 1/8” wide and 22.5 metres of line
3.   Fixed end of line to be held by an assistant (no stakes to be used)
4.   Line to be reeled in immediately after launch to avoid risk of entanglement
5.   Models may be scaled down from original designs that would otherwise be over 36” span.  Construction is to follow the form of the original with wood sizes being scaled to agree with the model’s scale

The Classic rules are identical except that : A classic model must be built in accordance with a design that was first flown, published or kitted after 30th December 1950 and before 1st January 1961 (January 1961 issues of magazines are accepted as published in 1960).

Why not have two classes

1. Anything goes

2. Vintage & Classic

Vintage and Classic models can be flown in 'Anything goes' but not vice versa.

I wouldn't mandate the line breaking strain as it just complicates matters, and I'd also suggest that the SAM rules are adopted for the rubber strip so that thinner rubber can be used if the model characteristics dictate.

That's my sixpennorth, now all I have to do is get my act together and finish my model which has been languishing for a while.

Peter
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applehoney
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« Reply #77 on: August 21, 2013, 09:43:03 AM »

If a cutoff date is applied that obviates any use of composites, etc, - and the development of modern advanced designs and airfoils -  it keeps the event within the reach and ability of all comers.
A very wide range of suitable models given that scaling of originals is allowed.

CA and epoxy -  present day materials that would not impact flying of these models.

Update:  PeeTee posted while I was pecking away.    It would be advantageous to the postal - and general encouragement - to have it able to attact all builders/flyers so common rules are desirable  ... even if those pesky metres are involved .... so perhaps an 'Open' event to get things rolling might be a positive move ... able to be fine-tuned with split classes, etc. at a future time when results and experience might dictate ?
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PeeTee
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« Reply #78 on: August 21, 2013, 10:22:20 AM »

I agree with Jim that it should be as 'open' as possible. As for models going down the FAI route, I'd suggest that competitors with a penchant for FAI flying are unlikely to be attracted to 36" Bungee launching, unless of course they are looking for a respite from carbon and Kevlar Wink

Peter
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lincoln
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« Reply #79 on: August 21, 2013, 12:18:08 PM »

These models are so small, the launch is so weak, and the optimum aspect ratio is so low, that I don't see any significant advantage to using carbon fiber, unless it makes a particular type of construction easier to do or more crash resistant. Of course, I could be wrong.
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skyrocket
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« Reply #80 on: August 21, 2013, 12:20:32 PM »

I like the 2 class idea...Vintage is really nice...seeing those old designs flying again...Walkin' Shoes anyone?...and I've been thinking about something for "anything Goes" with very simple construction, pod and boom and light...I agree with both Applehoney and PeeTee...
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« Reply #81 on: August 21, 2013, 04:55:38 PM »

I'm nearly done with the templates for a full-sized Walkin' Shoes Wink...

Can I play?
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PeeTee
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« Reply #82 on: August 21, 2013, 05:18:57 PM »

Quote
I'm nearly done with the templates for a full-sized Walkin' Shoes ...

Can I play?

Only if it miraculously turns out to be 36" span Grin Wink

As for the other replies, we appear to be in violent agreement Shocked
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lincoln
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« Reply #83 on: August 21, 2013, 11:09:46 PM »

I should be doing any number of other things, but I've started to build a very simple 36 inch towline glider to be used for bungee launch too. All sheet. The wing is just a sheet with  tilted down trailing edge stock at front and back. (Inspired by Perryman's "Stephanie's Solidiflier", but simpler.) I remember getting good results from Xfoil for this kind of shape at low Reynolds numbers, but I don't recall if I took it this low. (Maybe 30k??). I probably should have used a wider piece of wood, but I used what I had, which was 3 inches wide, and, with the two pieces of trailing edge stock, gives a chord around 4.5 inches.

The wing is glued up. Tomorrow I plan to saw it in half and put in the dihedral joint.

What's a good weight for this kind of glider? I'm thinking it might be 3 oz. or so.
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larry530
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« Reply #84 on: August 22, 2013, 06:41:38 PM »

Lincoln, if possible could you post a photo of your all sheet glider, would love to see whats possible. i have built several small bungee launch gliders that use a 12 foot length of 1/16 rubber and about 40 foot of thread to launch up and have been amazed that it worked so well , i look forward to the new 36 inch class and seeing what people build  Grin
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lincoln
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« Reply #85 on: August 22, 2013, 07:45:13 PM »

When it's done, I'll send a picture. Nothing much to photograph yet. Two pieces of trailing edge stock glued on either side of a sheet of balsa. And it might always turn out to be really lousy.
-------------------
Speaking of all sheet 36 inch gliders, here's one I found online called the Windrush:
http://outerzone.co.uk/plan_details.asp?ID=4347

http://outerzone.co.uk/images/thumbs/models/4347.jpg
http://outerzone.co.uk/images/thumbs/plans/4347.jpg


another all sheet, anonymous and undated, 30 inch, like a chuck glider but with a hook:
http://www.kurrawong.net/affp/_plans/Aus%20FF%20design0156.pdf

I ran across another interesting glider for this event, if the cutoff date doesn't matter:
http://www.kurrawong.net/affp/_plans/Aus%20FF%20design0059.pdf
Bungee Launch 36" Gliders
Bungee Launch 36" Gliders
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Hepcat
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« Reply #86 on: August 22, 2013, 09:04:13 PM »

The 'Windrush' was designed by Andy Crisp, one of the top English aeromodellers in many different classes.  As I remember the 'Windrush' was designed for a special Junior competition at the British Nationals. I  don't think it was a success despite its immaculate ancestry.  It probably did not seem an easy build to a lot of Juniors with its Jedelsky wing and certain other features.  More importantly all sheet aeroplanes can be fine if the builder has access to good wood and knows how to select it but, if not, the result is usually a clunker.

John B
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« Reply #87 on: August 23, 2013, 12:59:09 PM »

Built two wind rush gliders years ago with my two girls we flew them at the NATs had a great old time with them  Smiley
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« Reply #88 on: August 28, 2013, 03:58:56 PM »

While I should have been working on my own model, I discovered two interesting designs on the following page:
http://www.rcgroups.com/forums/showpost.php?p=18068825&postcount=3536
Both are 36 inch span, or appear to be, and are from the 1940's.

I don't think the Dolphin is the same Dolphin usually referred to. It's got a 6:1 aspect ratio, a reasonable airfoil, and a slick looking fuselage. You are supposed to carve the lower fuselage out of a big, thick balsa plank, but if that's a problem I think one might be able to carve a form in foam and then make up planks over it. (foam to be removed, of course) Anyway, I think it's a pretty interesting model.

IMHO, the Hooker doesn't look as good, although it's not unattractive. It has a much higher aspect ratio. (Maybe around 9 or 10?) Very thin airfoil which I suspect would perform quite well, perhaps making up for the high AR.  I wonder if it's strong enough? No spar, just the l.e. and t.e.
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Russ Lister
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« Reply #89 on: August 28, 2013, 05:09:09 PM »

Hoping to get my OD model ready for the 'Peterborough Rules' event at the Peterborough Flying Aces this weekend!

Sorry, no pictures .... am I taking this too seriously  Wink
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lincoln
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« Reply #90 on: August 28, 2013, 07:02:45 PM »

Did a bit more work on the all sheet 36 inch glider wing. Looks like it will be a bit porky. I'd guess 55 to 60 grams for the wing alone. I'm thinking it could be much less if the middle sheet (but not the l.e. and t.e.) were made from really light balsa. Maybe 2/3 the weight or less. But I wanted to see how it would come out with ordinary weight balsa. Pictures eventually.
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lincoln
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« Reply #91 on: September 04, 2013, 01:22:04 PM »

I'm a master of procrastination, though I have got a bit more done since the last post.

However, in the midst of my procrastination, I found a very low aspect ratio design that could be shrunk to 36 inches. AR appears to be between 4 and 5From Aeromodeller, AUgust 1949, it's called Dream Bogey. The airfoil is very thin but perhaps with a little too much camber for the low aspect ratio. But you can't have everything, and maybe it's still better than a thick one? I suspect a 36 inch one would fly quite well.

http://www.rcgroups.com/forums/showatt.php?attachmentid=5732894&d=1367028991
http://www.rcgroups.com/forums/showatt.php?attachmentid=5732895&d=1367028991
from this post:
http://www.rcgroups.com/forums/showpost.php?p=24837632&postcount=957
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« Reply #92 on: September 04, 2013, 02:58:30 PM »

While looking thru another thread, I came across the 35 inch "Baby Gull" by Gordon J. Rae (1946).  Quite attractive with THREE different tail options, but the wing is fairly narrow Undecided, and the build looks fairly intensive.  I downloaded/printed the plan anyway with remote intentions of building it.
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« Reply #93 on: September 04, 2013, 03:47:44 PM »

I just found a plan for the first towline glider I ever built. Jetco's Thermal 36, airfoil is just plane crummy and fuselage should be made lighter but:
http://www.outerzone.co.uk/plan_details.asp?ID=1572
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Dennis
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« Reply #94 on: September 04, 2013, 07:20:36 PM »

Seems like there's only one rib on the plan, and that looks like a moderately thin flat bottom. Worse than a 3 percent arc or something, but not so bad for such a small chord, I'd think? After all, they could have used an RAF32.
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« Reply #95 on: September 05, 2013, 03:15:35 AM »

  Here is my input to this topic.
Idea.... Take one Souper 30 P-30 wing and another stab that was available,
 build a fuselage for said surfaces and almost instant Bungee Launch Glider
is the result.  I have posted two pictures that are 3 weeks old.  In its current
configuration it sports a new 36" wing.  It took some tow hook adjustments
to get a good launch, but now I know where to position the hook to suit the
flying conditions.  I still need to optimize the glide somewhat.  When I get a
chance I will provide a new picture with the new wing.  I almost forgot to state
the weight which is 73.25 grams with the new wing.

Luke
Attached files Thumbnail(s):
Re: Bungee Launch 36" Gliders
Re: Bungee Launch 36" Gliders
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Luke
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« Reply #96 on: September 05, 2013, 08:09:52 AM »

I just found a plan for the first towline glider I ever built. Jetco's Thermal 36, airfoil is just plane crummy and fuselage should be made lighter but:
http://www.outerzone.co.uk/plan_details.asp?ID=1572
IIRC, it was also my first glider - ca.1956-7.  I thought it flew great - once I was able to get it to climb straight on tow (didn't have the experience adjusting the auto-rudder).

Got caught in one of Monterrey's soouper-boomers on it's third successful tow, never to be seen again.

I think Aerosente has the kit in their program
« Last Edit: September 05, 2013, 08:24:40 AM by Pit » Logged

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« Reply #97 on: September 05, 2013, 06:49:47 PM »

I think Aerosente has the kit in their program

No way do I want another one! I had no one to help me tow it into the air, one man tows didn't work. Other than glide nicely down a slope it taught me the basics of repair.
I'm still in repair mode, some things never change!
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Dennis
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« Reply #98 on: October 12, 2013, 07:45:24 PM »

An interesting and perhaps suitable glider from 1947, the Go Hi Mk VI. 30 inches:
http://www.outerzone.co.uk/plan_files_03/3545/GoHi_MkVI.pdf

corrected from Mk IV to Mk VI
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applehoney
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« Reply #99 on: October 12, 2013, 08:26:29 PM »

Not a bad little glider for its time  -  reaonable airfoil, areas and moments, hook in a more sensible position than many gliders of the era - and autorudder.   Could be a good bungee proposition
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