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Author Topic: Bungee Launch 36" Gliders  (Read 35832 times)
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PeeTee
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« Reply #250 on: December 27, 2015, 01:32:42 PM »

Van

If you download this software: http://shrink-pic.en.softonic.com/  it automatically reduces the file size of the photos to suit e-mailing or posting photos here. I've used it for years with nary a problem, and as I said, it does it automatically.

Cheers

Peter

ps the Wren is coming along nicely, I saw your photos on FFML
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FLYBOY49
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« Reply #251 on: December 27, 2015, 07:45:01 PM »

Here's another go at posting FROG WREN pic's

Van...
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Re: Bungee Launch 36" Gliders
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Re: Bungee Launch 36" Gliders
Re: Bungee Launch 36" Gliders
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FLYBOY49
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« Reply #252 on: December 27, 2015, 07:48:45 PM »

Again, more progress.
Van...
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FLYBOY49
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« Reply #253 on: December 27, 2015, 07:59:59 PM »

In that last batch of pic's I included a building tip that I thought I might share.

Before I start pinning parts to the plan for the fuselage, I use my old fashioned draftsman compass (divider to some) to measure and mark all the fiddly uprights and cross pieces directly from the plan.  Then, with them laying 2 at each station, I pin down the longerons and start gluing 'em in.

It makes 'em all exactly the same length, saves time, and makes building a l-o-t faster as well as more accurate.  It also helps if you take a minute to sand the ends to the correct angle right after you cut 'em to length.  This pic shows the uprights.  I do the same thing when attaching the 2 sides together. (Not shown in the pic's, tho.

The lead in the pencil end in mine is #2 and it works O.K.   But, if I still had some HB it would work even better when marking the balsa.  Haven't seen a supply of HB for some time.

Van...
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BigR
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« Reply #254 on: December 30, 2015, 05:55:34 PM »

Hi All,

I'm making a 36 inch Lulu scaled up from the "50th Anniversary" 30 inch Lulu Baby for the Haggard Bowden contest in Feb. at Perris. Rules say 25 feet of 1/8 inch rubber. Is this one strand 25 feet long or a 25 foot long loop of 50 feet of rubber? Approximately 10 feet per gram, so 2.5 grams or 5 grams of rubber? What do you use for the other 75 foot "string" and as a connector at the tow hook end? I assume a key ring or some such.

As you can see, I'm not a glider guy. Do know enough to use a hardwood spar though, since I folded the wing on a Sinbad at Mile Square with a "zoom" launch.

John in Kalifornia
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John in Prescott
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« Reply #255 on: December 30, 2015, 08:11:16 PM »

John,

It's 25 feet, not doubled, of 1/8th inch flat rubber and 75 feet of any light string.  I use fishing line.  Some use kite string or similar.  These little guys launch so sedately it is beautiful to watch.  No threat of folding a wing, tho.  But, I have successfully launched larger gliders on that same bungee.  It surprised me how well this launcher works.

On mine is a 1/2" split ring to attach  it to the tow hook with a small flag a short distance below the ring.  I am using a piece of a hanky.  My neighbor uses a few pieces (Maybe 4 or 5) of surveyors tape about a foot long.  These help pull the ring off the tow hook.

It also helps to angle the tow hook down from the belly of the plane a few degrees.

Van...
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skyrocket
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« Reply #256 on: January 24, 2016, 09:39:58 AM »

yes, that is the bungee set up we use for 36" bungee gliders...I've used it for A1's as well...I fly the Baby Lulu on a 3/32" rubber bungee set up on our small field and it is just right...I also fly a KK Cadet on this smaller set up and a auto-rudder to get a straight up tow....I have been using a 3/16" rubber set up on A2 size gliders and a total length of 160 feet. No problems yet. All set ups are with single strands of rubber and kite string. The thing I like about bungee is you can fly independently and get in a lot of flights without wearing your legs out and trim the models in a very short time. An adjustable tow hook is helpful too to make allowance's for wind strength on different days. I've been using fuse D/T but it is time to start thinking about a timer.
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BigR
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« Reply #257 on: January 24, 2016, 06:32:45 PM »

I made up the towline with the suggested rubber and used braided fishing line. When I got out to the field I found the the tow reel, an old orange and white FAI sullpy item, had become disassembled. What a mess!

The Lulu had a nasty stall which I corrected with lots of nose weight. I think I'll recheck the CG and incidence settings. Next time I'll be more prepared.

John
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John in Prescott
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« Reply #258 on: January 25, 2016, 11:26:12 AM »

I keep the line/rubber on a large kite reel and tangles do occur all the time...I put the line/flag/tow ring on first and that makes the rubber first so I can attach the rubber to the post and then walk out the set up out...by doing this I can drop off the reel at the post and pick up the glider and fly...with the 1/8" rubber set up, I pace off 20 to 30 steps and start flying...the more wind the less paces...try to keep the auto rudder as simple as possible...Baby Lulu came out at 29.4 grams new and I modified the airfoil with a slight under-camber...
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dohrmc
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« Reply #259 on: July 18, 2016, 06:54:01 PM »

I just flew my first Hi Start flights this weekend with a Retro RC Gnome glider. It is a nice little glider. Based on the instructions in the kit, I used 50' of 1/16" rubber, and 100' of line. I was amazed to see that 1/16" rubber works perfectly well, and hauls the model all the way up to the top of the line.
This event will become a standby in our club, as we have many glider fliers who are getting too old to go tearing around with a towline.
The Retro RC kit is laser cut, and makes a fine glider.
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skyrocket
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« Reply #260 on: August 25, 2016, 10:11:36 PM »

I'm building a 36" Lulu right now from the 30" Aeromodeller plan I enlarged...seems to be going together nicely...the 30" Lulu is a nice small field flyer so I don't see any trouble coming soon...will build the wing tomorrow and start covering it next week...waiting for the tracker I ordered last week and will try to fit it in Lulu and retro-fit the transmitter to various other models because I've finally reached the point of getting tired of loosing good flying models in the soy beans and corn at Geneseo...it's not a question of money but one of feeling not good enough to warrant one...it's frustrating as hell being close to finding a model when the soy beans just suck it up even when you have a good line on it...does anyone know which of the button timers is the best for small models because I'd like to replace using fuse?...is a button timer the same as a Silly Putty timer or should I try a Tomy style timer?
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Graeme H
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« Reply #261 on: August 26, 2016, 08:03:12 AM »

Was out flying with my 2 small gliders the other day, a Frog Wren and a Dizzy
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calgoddard
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« Reply #262 on: August 26, 2016, 10:25:45 AM »

This is in response to Reply #260.

Try the larger Munson badge timer.  It is available in longer and shorter durations.  You can buy them from Starlink Flitetech and Volare Products.

As I understand it the old timers that used Silly Putty were hand made and have mostly been replaced by the Muson badge timers. These are viscous damper mechanisms with a rotating arm.  The arm is rotated manually to an angular position to set the desired DT trigger time.

Where I live fuse timers are not legal due to the fire danger that they allegedly pose.  So we use viscous damper mechanisms because they are inexpensive, and lightweight. I actually prefer TOMY timers for this application, but they are a little heavier (3 - 4 grams) and require some tweaking. They are more accurate and reliable.

The best timer, in my experience, is the BBT electronic timer from Starlink Flitetech.  It weighs about 3 - 4 grams including its battery and is programmable in 5 second increments up to 5 minutes. It is extremely reliable and highly accurate. I think it sells for less than $50.

I am a slow builder.  When I get a model completed and trimmed so that it is flying well I cannot bear to lose it.  For bigger models, like OTR and coupe, I install both an electronic timer and an RF tracker.  They can easily carry the extra 6 - 8 grams and still be competitive.

For smaller models, like an Embryo or a Jimmie Allen Skokie, I use a viscous timer button and put up with its relative inaccuracy.  I had my Skokie DT early at a contest recently when it was still gliding well 50 feet above the ground. That flight ended up being 98 seconds and the early triggering of the DT probably cost me a max.    

A friend of mine just built a 30 inch wing span LULU glider. I can't wait to see how it flies.

PS - Nice looking models Graeme H.

    
« Last Edit: August 26, 2016, 10:45:28 AM by calgoddard » Logged
skyrocket
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« Reply #263 on: August 26, 2016, 12:55:53 PM »

Almost have the 36" Lulu wing built...I will try the Munson timer from Volare...thanks...the 30" Lulu does fly really nice...I'm using 1/32" geodetic ribs in 36" version to cut down warps & weight but the rest is per plan...my buddy flies a Frog Wren on bungee...good looking model...we use 3/32" rubber on the smaller models and suits our small test field...back to it!
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applehoney
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« Reply #264 on: August 26, 2016, 02:12:08 PM »

Occurred to me that I never, as far as I remember, documented the 36" version of the 'Walthew A/2"  that I built two winters ago, spurred by  the fact it had reasonable wing area for its size and the thick flat-bottom airfoil did not deter me.  Such worked beyond my expectations on my old 'Night Owl' beginners glider.

However initial enthusiasm waned as it became apparent that the Walthew was more in the running for the ugliest clumsiest design award.  At Geneseo - May 2015 - it did show a shortlived promise of flying ability but fell out of an off-field tree and destroyed the fuselage back to the wing.  Though I still have the pristine flying surfaces I just can't imagine building another fuselage for the thing!
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Yak 52
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« Reply #265 on: August 26, 2016, 03:09:50 PM »

Was out flying with my 2 small gliders the other day, a Frog Wren and a Dizzy

Looks nice Graeme! Welcome to the forum. How were you launching them?

Jon
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Graeme H
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« Reply #266 on: August 26, 2016, 03:56:43 PM »

Just off a bungee, 25' of rubber and 75' of listing line
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« Reply #267 on: August 31, 2016, 10:24:44 AM »

Just finished the 36" Lulu and it came out at 44 grams and I'm pleased with the build...didn't tissue the fuselage, just 3 coats of Ace Hardware's spray Lacquer and tissued the wing, stab and fins with 2 coats of lacquer on each...I still used a fuse but will have to buy some of those button timers for these small models...pics later after flight testing some time this week...
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Pete Fardell
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« Reply #268 on: September 03, 2017, 07:21:05 PM »

I think a 3 ft bungee glider might be a good way for me to get into a bit of gentle non-scale competition in a low key way. I might try and build one for next summer. There are also one or two opportunities (eg. Oxford Scalefest) to fly scale gliders in FF competition. I was wondering if it's possible to make an uncomplicated scale glider which is also at least vaguely able to compete with non-scale designs so that I can build a 'two birds with one stone' model. Is this a daft idea? If not, which real gliders most closely resemble good hi-start designs?
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« Reply #269 on: September 03, 2017, 08:44:54 PM »

I have just finished building another Frog Wren.  Lost the original one day after completion when my cabin burned to the ground.  Lost my entire building area, all tools and many  models.

But, I almost finished building another place to live and have accumulated most of the necessary building tools and supplies.  The 1st Wren took about 3 days to build.  This one has taken several months.

This one has a Tatone D/T timer. It's tissue over Mylar.  Built from a Bob Holman short kit with Jim O'Reilly plans.  They make building a model a dream come true.

Hand gliding in my small lawn is good.  I'll try bungee launch this coming weekend at Point McKenzie where we hold the Alaska SAM annual contest.  It's a one mile square farmers field that we get to play in after his 2nd cutting of hey.  The farmer keeps a mowed lawn runway in the center for us and we have permanent pit tables set up.

I'll also be taking along a restored Jetco Thermic 'C' that I built many years ago and a couple rubber models that have been hanging on my shop back wall for many years. If I get enough time to putter with it I'll include a Tomboy with a Pfeffer diesel.  I still have one each, F/F and R/C that have been to Boulder City, Nevada and back. (SAM CHAMPS, ya know. I'm scheduled to do that again this October.  So, gotta get crackin' to get stuff ready.

BTW: Jim,  I like the looks of that glider you said was UGLY! (Walthew A/2)  It looks good to me and I would consider making one this winter  if I had the plans or knew where to get 'em.

Van...
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applehoney
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« Reply #270 on: September 04, 2017, 12:34:49 AM »

Van - sorry ...didn't keep the tileprint plan of  the Walthew.

Contact Derekk Scott   www.model-plans.co.uk     He'll provide you with a plan at nominal cost and likely print to 36" span for you, too.
 
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Yak 52
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« Reply #271 on: September 04, 2017, 04:22:56 AM »

I think a 3 ft bungee glider might be a good way for me to get into a bit of gentle non-scale competition in a low key way. I might try and build one for next summer. There are also one or two opportunities (eg. Oxford Scalefest) to fly scale gliders in FF competition. I was wondering if it's possible to make an uncomplicated scale glider which is also at least vaguely able to compete with non-scale designs so that I can build a 'two birds with one stone' model. Is this a daft idea? If not, which real gliders most closely resemble good hi-start designs?

Pete,

There is a scale glider prize in the Peterborough Flying Aces 36" bungee launch competition - held last weekend (but I was on holiday unfortunately). Monique won this a few years back with a Slingsby Kirby Prefect enlarged to 36". There's a thread on here if I recall.

Anything with low aspect ratio and plenty of dihedral effect would be a good starting point. The dihedral makes all the difference in windy conditions and low aspect ratio maximises launch height.

Jon
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Pete Fardell
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« Reply #272 on: September 04, 2017, 04:38:02 AM »

Thanks, Jon; yes, it was noticing the scale prize mentioned on the Peterborough results last night that made me think of the idea. Good to know it's a goer. High aspect ratio and dihedral noted, I shall start scheming! I might just do a Prefect like Monique's.

EDIT: I've just noticed you said LOW aspect ratio, not high. Do you mean low compared to other gliders, or just low? Presumably it still needs longish wings?
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« Reply #273 on: September 04, 2017, 04:45:13 AM »

Low aspect  Wink another benefit is it gives a lower wing loading.

It's a pain for scale because high aspect ratio is one of the thing that makes a good full size glider  Undecided but older vintage gliders tend to be lower aspect so that's no bad thing  Smiley
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Pete Fardell
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« Reply #274 on: September 04, 2017, 04:47:38 AM »

Thanks, Jon. I think your correction and my edit crossed in the ether. That's nice and clear though.
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