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Author Topic: Bungee Launch 36" Gliders  (Read 34934 times)
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FLYBOY49
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« Reply #325 on: May 25, 2018, 12:21:30 PM »

My 1st choice for this event was a FROG WREN.  Bob Holman has laser cut short kits for it.

I've built 2 of 'em and tehy fly a treat.

Laser cut kits are also the fastest way to build and the parts are so much better cut than I can do from scratch.

Jim O'Reilly makes the plans and both he and Bob Holman can supply both plans and short kits.

I'm currently attempting to build 2 more Thermic 'C's which are 36" W.S.
I found plans for a very rare JASCO 1944 model that is different than the popular 1946 model.  It's on my bench now, ready to cover.
Next up will be the JASCO 1946 model.
Then a 'V' tail model a shown on the 1946 kit box.

And I already have a JETCO model built many years ago.

That'l give me 4 models of the THERMIC 'C' to take to the SAM CHAMPS in October 2019 at Boulder City.

BTW: I sent a copy of the rare JASCO 1944 model to Roland Friestad, the editor of SAM SPEAKS and R/C MICRO WORLD.

He is planning to include that plan in the up coming issue of R/C M.W.

Van...
Balsa dust is absorbing,
It absorbs the troubles of the day.
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JohnOSullivan
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« Reply #326 on: May 25, 2018, 05:07:44 PM »

I have a 36" free flight called the Squiggle. Plans are available for download at Outerzone.

https://outerzone.co.uk/plan_details.asp?ID=3758
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John O'Sullivan
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Pete Fardell
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« Reply #327 on: May 30, 2018, 08:03:03 AM »

Thanks for the responses.
Before I enlarge the Frog Petrel plan, a quick question...
The rules on the Peterborough MFC website say that the 36" is measured tip to tip, and NOT flat span. Is this the case generally for these histart 36" span contests?
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billdennis747
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« Reply #328 on: May 30, 2018, 08:29:55 AM »

I don't know Pete but I would think Dreaming Spires will also use Peterborough rules. Are there any others?
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Pete Fardell
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« Reply #329 on: May 30, 2018, 09:11:32 AM »

There's the Buckminster event in Sept, but I think that'll be run by John Ashmole or another Peterborough chap anyway won't it? In fact, I daresay the Peterborough rules ARE the rules as far as the UK's concerned, so shall proceed accordingy unless I hear otherwise.
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PeeTee
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« Reply #330 on: May 30, 2018, 09:49:47 AM »

I agree Pete, the Peterborough rules are as good as any!
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RalphS
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« Reply #331 on: May 30, 2018, 11:08:33 AM »


Hi Pete - didn't see you at the windy nats.
 
The rules on the Peterborough MFC website say that the 36" is measured tip to tip, and NOT flat span.

Isn't that the same?  Just people writing rules for their clubmates rather than for the FAI or having to subject themselves to interogation by the likes of JOD. 

Probably a similar reason for 36" span rather than some metric dimension plus area plus weight restrictions.  Mainly with the idea of using the simple 1940/50's designs they built as lads.

Ralph

Ralph
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Pete Fardell
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« Reply #332 on: May 30, 2018, 11:49:34 AM »

Hi Ralph. Sorry to miss you. I was probably too busy breaking my models!

With a design like the Petrel, with considerable tip dihedral, I think I'll gain a few square inches of wing area if I measure the 36 inches as a gap the finished model can pass through, rather than as if the the wing was still flattened out on the board. However my aim is certainly not to extract every last advantage from the rules, but to simply end up with a model which is definitely eligible for these fun comps. So if there's any doubt at all I'll play safe and just enlarge the wing plan to 36".

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FLYBOY49
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« Reply #333 on: May 30, 2018, 12:20:55 PM »

NOTE TO 36" glider fans.

I recently discovered that there are 4 different Thermic 'C' designs.

3 by JASCO and one by JETCO.

I am currently building one that has a 1944 date on the bottom of the plan.

It differs from the more popular 1946 plan.

Then there are a couple different pictures of a 'V' tailed one.  One on the 1946 kit box and another reference on the 1944 plan.

Finally the JETCO one is a whole redesign with sparless wing and tail feathers that use trailing edge stock for both leading and trailing edges.

I'm gonna try to build all 4 models for the 2019 SAM Champs in Boulder City.

Side note: I discovered that the pod notches in the printed wood of the 1944 model suck muddy pond water!  So if'n ya try building one of them, plan ahead and put the notches in after gluing the bulkheads to the keel sheet.

Van...
Balsa dust is absorbing,
It absorbs the troubles of the day.
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TheLurker
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« Reply #334 on: May 30, 2018, 01:05:42 PM »

Ahem.  The Parish Idiot has a question....

I've got about 5 yards of 1/4" flight rubber (that I found in a newsagents1) cluttering up my spares box.  Am I right in thinking that it'd be far too beefy for launching a 36" span model of about 80g-85g and that with a patched up wing?   If it is too beefy would I get away with 3/16"?


1 - One of those frozen in time2 places that you only ever stumble over when you're on holiday.
2 - Late 1967 I think.
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cvasecuk
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« Reply #335 on: May 30, 2018, 01:38:46 PM »

I would recommend 1/8". The rules state:- Hi Start 7.5m of 1/8” rubber Plus 22.5m of line
Ron
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TheLurker
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« Reply #336 on: May 30, 2018, 02:00:39 PM »

Evening Ron,

I should have made it clear that this isn't for any sort of competition, it's just for general mucking about and my main concern is to not overstress the patched up wing.  I take it you'd go for 1/8" for general mucking about?

Lurk.
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billdennis747
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« Reply #337 on: May 30, 2018, 02:21:48 PM »


I should have made it clear that this isn't for any sort of competition, it's just for general mucking about and my main concern is to not overstress the patched up wing.  I take it you'd go for 1/8" for general mucking about?
1/8" works well. The first thing I learned is that it isn't a catapult - the model more or less kites up into wind
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Yak 52
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« Reply #338 on: May 30, 2018, 02:40:41 PM »

Pete, yes, it's projected span after the dihedral has been built in.


Lurker,

You'll find that if you use a short powerful bungee you may get a disappointingly quick release and possible loop off the line. The long steady pull of a long low stretch bungee gives a nice 'kiting' climb. Add some wind into the equation and the forces get fairly stiff on wing spars etc. (That said a more powerful bungee gives more climb when there is no wind.)

Have a play around but more power doesn't mean more height. You just want a long steady pull that is matched to the glider weight. At your stated weight 1/8" rubber is plenty.

The real trick is getting the model to fly off the line at full height and still under tension  Smiley


(You could use your 1/4" rubber for catapult gliders though - 2g of rubber in a loop.)

Jon
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FLYBOY49
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« Reply #339 on: June 17, 2018, 11:13:16 AM »

Happy Fathers day to all.


Yesterday I picked up a small older Olds van at an impound auction for $25.00.  It has a rather nice set of tires on it and the whole thing seems very clean.  No damage at all, other than some bottled trash left inside.  Just might make a good model wagon.


Spent some time yesterday and will again today make balsa dust.  Got a 'V' tailed Thermic 'C' almost finished. 1944 version.  I already have the 1944 conventional tail model completed and the Jetco version.  So, that still leaves the 1946 versions to build. (Both conventional and 'V' tailed.) That'll give me 5 Thermic 'C's to take to the SAM Champs in 2019.


Van...
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Pete Fardell
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« Reply #340 on: June 17, 2018, 01:01:14 PM »

I've started my FROG Petrel after printing out the plan slightly enlarged to 36 inches span.
Sides are made as are formers F3 and F4, all built over the plan. I'm slightly confused about the other formers though as unlike F3 and F4 these are not shown except as black lines on the side and top views. Are these formers meant to be built up like F3 and F4 (in which case why aren't they also drawn?) or are they perhaps simple sheet balsa rectangles cut to size using the dimensions on the side and plan views?

The instructions (attached) don't really help, unless I'm just missing something.
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Re: Bungee Launch 36" Gliders
Re: Bungee Launch 36" Gliders
Re: Bungee Launch 36" Gliders
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Indoorflyer
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« Reply #341 on: June 17, 2018, 01:50:24 PM »

They were probably just rectangular bulkheads on the printwood, with notched corners. F1 by itself holds the spacing of the fuselage sides, just behind the noseblock.  F2,5,6,and 7 would appear to butt up against the stripwood verticals of the sides, and the corresponding cross members. (according to the instructions, the formers go in first, then the stripwood crossmembers follow)
In Fig 1, it looks like the part labeled S1 should be S2.  There probably should be a gap between S2 and the vertical just behind it, so that former F2 can be "captured".   The plan also infers that there are 2 "S1", the bottom one is glued in place, the upper one is the "lid" to the ballast box.

That should be a pretty model, it certainly has nice lines.
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Re: Bungee Launch 36" Gliders
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Make the same mistake on both sides; nobody will notice...
Pete Fardell
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« Reply #342 on: June 17, 2018, 02:05:42 PM »

Thanks, I.F.- that all makes sense. I'll proceed accordingly...

(I'm so used to making rubber models, and so UNused to building gliders, that my first assumption was that the formers would have to have a hole in the middle. Presumably for the ... er ... nonexistant motor to pass through. I know. Roll Eyes)
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FreeFlightModeller
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« Reply #343 on: June 17, 2018, 07:20:27 PM »

I can't really see at the size the plan is shown, Pete .... but doesn't the isometric drawing of the nose assembly show solid formers to form a weight box?

EDIT: I realise now that you are referring to the rearward formers?
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OZPAF
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« Reply #344 on: June 17, 2018, 08:02:09 PM »

My reading of the plans is that F1,F2 are as IF mentions to hold the nose shape and form a weight box and are solid. However F5,F6 are as indicated by the small isometric sketch near them, meant to be built up similar to F1,F2.

With no drawing for them, I don't think it would be best to install them before joining the sides. I would suggest adding the vertical legs of the formers to the inside of the fuselage uprights - before joining, but leave the horizontal crosspieces of the formers until after joining the sides as normal. The horizontal sections of F5,F6 could then be added - similar to F1,F2, over long and then trimmed back. This approach would help to avoid distorting the curve of the fuse in plan. F7 could be handled the same way.

Hope that helps.

However I must admit to wondering why formers were needed where F5,F6 are anyway. I would be inclined to leave them out!

John
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Pete Fardell
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« Reply #345 on: June 19, 2018, 05:09:08 AM »

Many thanks for the responses. I've decided to just make the formers from doubled up (cross grained) sheet, but F5 and F6 will be there only to keep things square and will be knocked out once the cross pieces are in.

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Pete Fardell
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« Reply #346 on: June 21, 2018, 04:30:18 PM »

The Oxford deadline has kept things moving along on the Petrel. Hopefully I'll be ready to cover it at the weekend, still giving me a few days to mess about with DTs and such.
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Re: Bungee Launch 36" Gliders
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OZPAF
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« Reply #347 on: June 21, 2018, 08:25:26 PM »

It almost looks like it needs a rubber motor Smiley In this age it is unusual to see a full fuselage and cabin on a glider but it just shows how attractive some of these designs were.

John
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FLYBOY49
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« Reply #348 on: June 22, 2018, 12:55:36 AM »

Looks great, Pete.

Are those landing gear in the background or training wheels, eh?

Van...
Still working on my 1944 'V' tail Thermic 'C'.  Almost ready to cover the pod.  Tail feathers are covered. Using one wing for both the 'V' tail and the conventional tail.
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Pete Fardell
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« Reply #349 on: June 23, 2018, 07:39:40 AM »

Thanks, Flyboy.

Everything ready for covering now, so here are a couple of final uncovered shots. Weighs 27g at the moment, although I've no idea what that means (but if only it were a 3ft span rubber scale model I'd be getting quite excited!)
Really enjoying this glider lark so far.
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Re: Bungee Launch 36" Gliders
Re: Bungee Launch 36" Gliders
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