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May 01, 2009, 05:14 PM
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Discussion

The History Of The Tw(in)otter


The plans for the twin otter 480 were purchased in november 2007, and construction was started, almost before the plan hit the door mat!!!

Construction started with the fuselage, because i was awaiting the arrival of the motors and g/boxes for the wing.
It all came together very quickly ( ah the joys of cyano )and within a few weeks i had something resembling A TWOTTER fuselage.

The wings were then started, an proved a bit more fun due to my limited build space (the wings were almost as long as my bed, which meant they were longer then the desk in my bed i use as a building board!)

The decision was taken early on to include the flaps, as tbh i just like the extra complication, and the extra scale character they add.

By early march 08, the wing and fuselage were made, but not fitted out or covered. Picking a colour scheme, and finalising the cockpit/nacelles took the most time (mainly because uni and other things were getting in the way! )

A slight mas-hap was had in mid may, when after covering, and during an engine test, one of the ESC's failed, and reverted to full power.
The result, was a TWOTTER Mk 298!! i.e. a 300, but missing quite a bit of the nose! thanks to the crash, with a brick wall in my garden (it shot quite a long way in not a lot of time) it also broke the wing mounting and the upper forward fuselage (sorry no pics- i'd rather forget it)

After spending time on the shelf, whilst the rest of my life was dealt with, it was then un-shelved early 2009, and finished off.
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Oct 26, 2009, 12:50 PM
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Its Still Flying


Having had the twin otter up twice this week, with both sets of batteries on both occasions, i have come to a few conclusions

1: i've slowly been tweaking the cg backwards, and it has made the TWOTTER a little more fun to fly, without being excessively unstable

2: the rearward cg, helps the t/o run, as less trim speed is needed
though on approach, care has to be taken to stop the nose rising too much

3: FLAPS today, i had the twotter hovering in a slight headwind
and i'm now down to a full power, full flap take off run, of under 10ft

hopefully some more pics of this wonderful plane to come, when the weather, my lectures, and a camera, all happen to coincide
scott
Nov 08, 2009, 05:49 AM
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wallis_100's Avatar

Twotter flying pics


Went out flying last night.
Nearly left it too late, but managed to get about 25-30 mins, whilst putting on a show (stall turns, barrel rolls, loops and attempted inverted (in a bit of a hessitating barrell roll)) for the demanding friends and cameraman.

Got the plane down safely only to snap a prop, as i caught a branch on the ground whilst taxying to the pits...

Hope you enjoy the photos...
Number 11 proves only 1 thing.... i need to get on and make a cockpit with pilots, it looks rather creepy with a pilotless plane flting at you

scott
Last edited by wallis_100; Nov 08, 2009 at 12:50 PM.
Nov 30, 2009, 05:11 PM
build like there is no 2moz
wallis_100's Avatar
The twotter went flying last week, in some failry windy conditions

Video is here:
RC Twin Otter (5 min 40 sec)


enjoy

scott
Jan 23, 2010, 02:52 PM
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flying from the wet stuff


During the snow i decided that the floats on the twotter would work well as ski's-- i was right , it flew beautifully, though i still seem to be lacking performance from the lipo pack i used when it was really cold think i may have damaged the cells
pics are here: https://www.rcgroups.com/forums/show...postcount=1035

Info on the floats can be found here: https://www.rcgroups.com/forums/show....php?t=1046503

than today, whilst at the sailing club for a first aid course, i had the urge to fly it off the slipway and out of the harbour, taking off into the solent.
Thankfully by 4pm, the wind and waves were obliging, and despite a small snarl up (the safety arming switch on my ESC had a wire failure (which i repaired before flight)) off we went. The take off throught the solent swell was nothing to worry about as it was a fairly long gentle rolling type. And soon i was performing loops, for the assembled crowd

Then a nice gentle touchdown and taxi to shore.

I'll see 2moz if the onlookers (part of the sailign club) got any video
scott
Last edited by wallis_100; May 27, 2010 at 09:28 AM.
Feb 28, 2010, 02:55 PM
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Doug Bartley's Avatar

Twin Otter power:


Hey Wallis: Is this the 480 or 600 size. I have Ivan's 600 size plans on there way to me now!
Which ever size your running, please tell me the power system -- brushed/brushless/direct/geared/ power sytem weight/ battery size/s??? Do you run a separate BEC/ reciever battery?
I can't wait to get the plans. This twin otter will look so good alongside my Unionville 6ftRadial and 6ftTurbo Beavers!
Trying to decide whether straight direct drive with 11/7/3 blade or geared with 12/8/3blade for scale -- two totally different systems!
Have you ever used Cobri gearboxes? Any good?
OK that is enough for now! Thanks in advance Doug
Feb 28, 2010, 05:23 PM
build like there is no 2moz
wallis_100's Avatar
Hi Doug

The twin otter i made is the 480 size
My power system, is 2 jamara long can 400's (approximately 480's) brushed motors, geard 3.9:1 running 10*6 inch 2 blade props (still tweaking different makes of prop, as it had 10*5, but is better with 10*6 ... i tend to swap them over, when i break one lol)
This is powered with a 3s1c 11.1volt 4000Mah lipo (some cheap chinese make)
This provides reasonable power (sometimes i wish i had more, but thats only so it would do more aerobatics )
I get between 30-50mins on the battery per charge (without hitting LVC) depending on what i'm doing.It runs a standard BEC equiped ESC (only 1) powering standad servo's and the 2 motors in parrallel
I have the optional flap function, and i thuroughly recommend it (not a great deal more weight, but a lot of fun)
I have no idea of systme weight, but the plane, weighs 1700g ready to fly, and just shy of 2000g when i add the floats (and it still flies sweet )

hope this helps

scott
May 03, 2010, 04:15 PM
Registered User
Doug Bartley's Avatar

Twin Otter power:


Thanks Wallis: I have not started my TO 600 size yet. I'm using Turnigy 4240-900 motors to allow me to spin 12/8/3blade props. The are capable of 550 watts each, ridiculous power for this plane, I intend to run them at about 300 watts each.
I expect my build will go over the 100 oz build weight specified, but watching Ivan's Twin Otters fly, I don't have any doubts about being a pound or two heavier.
I had all the wood purchased, but I'm now using some of it to rebuild my 96" Unionville Turbo Beaver. Pete the pilot decided he should fly into the only large elm tree near the field while attempting to land on his fifth flight!!
End result is the Twin Otter won't get started for a while now!
May 04, 2010, 03:37 AM
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Doug

even at 300W per motor your nearly double what i have in total at full power....

that will fly sweeet

just remember IANS weights, were with brushed motors and NICADS so, with LIPO, and brushless, the extra power and reduced weight go a long way.

good luck with it and put a build thread up when you get started.

one thing to watch that we've just noted on the twin otter 480, is the size of the ply U/C plate is wrong, its drawn right in the plane, but is stated an inch longer then on the plan...


scott
May 11, 2010, 06:04 AM
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wallis_100's Avatar

Major overhaul


During the recovering process, i decided to strip the plane bare and inspect everything, see how it was handling my rough treatment...
well i found the ply undercarriage plate had debonded from the fuselage stringers, and that several of the smaller uprights, have come loose around the cockpit,
Oh and that in one of my rough landings the nose wheel must have hit the belly of the plane!!!!!! coz there is a shocking dent and crack.

Still, superglue, and some epoxy, and she'll be fit and ready for the bimbo event in a new colour scheme.

scott
Last edited by wallis_100; May 11, 2010 at 06:04 AM. Reason: spelling
Jun 01, 2010, 05:27 PM
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new scheme


I have posted this elsewhere, but thought i'd add a few more pics here

I will add pics of the pilot/cockpit, when its finished

enjoy
Aug 27, 2010, 03:51 AM
We Do It With FRQZ
RM_Sparks's Avatar
damn that looks good the second one
Aug 28, 2010, 05:33 AM
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wallis_100's Avatar
dkintx
ta, it was my first attempt with profilm.
still need to do the decals on the fuselage, and fin, but its much easier to see then the white and blue.

in fact i used this very plane to pass my BMFA A certificate (solo flying certificate) last week

scott
Sep 01, 2012, 12:34 PM
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Rip


After a bit of pilot induced error at yesterdays flying during this years BIMBO 2012 meeting, and an overnight repair.
All was looking well as a repaired Twin Otter took to the skies once more.
Then about 3-4 second in, as both wheels clear the deck, a gust hits, and she starts a slow left roll.
Simple... add a little right aileron (and i had checked this before- and after so can varify it was the right way round) NO EFFECT
Ok, add a bit more... STILL NO EFFECT and she is now nearing 45 degrees left bank (trying to climb)
HAD i been thnking straight, i'd have flipped it to high rates, and may have had enough to save it (HINDSIGHT IS A B***H )
Ok, desperate last attempt as the wing hits near vertical (Opposite rudder to hold the nose up, or level the wings-- NO NOTICABLE EFFECT)

Net result, wing spar sapped clean through at outer panel lines, and in the centre section too. Fuselage bent and broken back to beyond the wig root..

I guess the old girl had had enough- RIP Sorry you had to go this way.
You will be missed
But at least it gives me some space for something else


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