Twin Otter Ready for a Swim  
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Twin Otter Ready for a Swim - 4/21/2008 1:49:22 AM   
vonJaerschky



Posts: 204
Joined: 8/25/2002
From: Comox, BC, CANADA
Status: offline 		My trusty old Twin Otter has been flying steadily for almost 5 years now, and it has become my favourite flying airplane. I've used it for still photos and video, and now it's time for the next chapter - Float Plane!

I am really looking forward to the big electric meet in Chilliwack in a month's time, and part of the fly-in is a float fly at the local pond. I've only tried floats once, many years ago, and it was a cold, wet, humbling experience involving the South Pacific, partial nudity, and hypothermia. This time I have a better platform and some other float fliers to help me out.

The floats are from Slocan Floats here in BC. They are 34" long, foam core, and come already covered with 2oz fiberglass cloth and have a coat of grey primer applied. I gave them a light sanding and painted them with Krylon aluminum paint. The front struts are 5/32" wire with some aluminum streamline tubing for fairings. I used some maple blocks to make mounts inside the fuselage to receive the front struts, and the struts themselves are held to the floats with nylon nose gear mounts. I used short pieces of dowel epoxied into the floats to receive the screws that hold the nylon blocks to the floats. The front struts easily slip out of the fuselage by undoing two wheel collars, and I can convert back to wheels in about 10 minutes.

I am not going to use a water rudder. I am using my Spektrum DX7 in this airplane, and I have made use of the programmable mixes so that I have differential thrust. One ESC is plugged into the throttle channel, and the other into AUX2. One mix is permanently on, and mixes the throttle channel to Aux2, so that both motors respond equally to the throttle as per normal. Then, I have two mixes that are activated at the same time by the same switch. One mix is RUD>THROT, and the other RUD>AUX2. Left rudder increases the power to the right motor, and right rudder increases power to the left motor. I just need to always remember to flick the mix switch from "Taxi" mode to "Flight" mode before commencing the take off run, or things will get interesting! This system works like a charm on the bench. Just sitting on the garage floor, I can spin the airplane clockwise and counter clockwise with the differential thrust. I have high hopes this will work on the water. I'm not sure if I'll get a chance to try a test flight before Chilliwack. I have a lot of water around me, but most of it is salty, so I'd rather avoid that!


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RE: Twin Otter Ready for a Swim - 4/21/2008 3:03:27 PM   
Prairie Mike


 

Posts: 113
Joined: 1/22/2003
From: Auburn, KS, USA
Status: offline 		tell me more about your Twin Beaver. glo or electric? engine/motor size? where did you get it? scratch built or kit?

_____________________________

Mic on the Prairie

(in reply to vonJaerschky)
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RE: Twin Otter Ready for a Swim - 4/21/2008 3:36:54 PM   
vonJaerschky



Posts: 204
Joined: 8/25/2002
From: Comox, BC, CANADA
Status: offline 		Scratch built from Model Airplane News plans. It's electric, 60" wingspan, two Nippy Black 1812/100 motors. It's a great flying airplane. Not true scale by any means, but its convincing enough. There are more pictures of it on wheels taken at last year's Chilliwack fly in here http://teamtracon.netfirms.com/eventgallery/nfpicturepro/thumbnails.php?album=12 . It's become my general fun flying airplane. I have also taken quite a bit of video from it, and posted them on Youtube. Just search for "vonJaerschky twin otter" and you should get a few hits.

(in reply to Prairie Mike)
       Post #: 3

RE: Twin Otter Ready for a Swim - 4/22/2008 4:26:40 AM   
vonJaerschky



Posts: 204
Joined: 8/25/2002
From: Comox, BC, CANADA
Status: offline 		Here's a few more pictures of the Twotter ready to hit the waves. I've painted the strut work, attachment points, and the rest of the floats themselves.

One of the more distinctive features of the Twin Otter when the floats are strapped on are the distinctive additional small vertical stabilizers on the top and bottom of the horizontal stabilizer. I guess the full size aircraft needed the additional vertical area for stability. It's one of those "Neat-o" things that stands out on the airplane, so I made some for the model, too. I just used sheet styrene to cut out the shape, and then cemented on a strip of 1/8" wide sheet styrene to give it a base for gluing. Then I simply glued the fins on using a small smear of silicone rubber. I don't know if they will help the stability of the model, but they look cool!

Empty weight of the airplane on wheels is 59.2oz. Empty on floats is 71.4oz, for a difference of 12.2oz. I guess that's not too bad. The total weight of the floats and all the associated struts, nuts, and bolts is 17.2oz, the difference of course being the weight of the wheels and nose gear strut. The CG did shift a bit, but I was able to compensate by sliding the battery pack rearwards about 2 inches. I'm glad I didn't need to add more weight for balance.

I can't wait to try her out on the water!


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(in reply to vonJaerschky)
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RE: Twin Otter Ready for a Swim - 4/23/2008 7:09:10 PM   
Goinstraightup



Posts: 2147
Joined: 12/10/2002
From: Baraboo , WI, USA
Status: offline 		Nice plane!!!!!

(in reply to vonJaerschky)
       Post #: 5

RE: Twin Otter Ready for a Swim - 4/23/2008 8:07:47 PM   
N7OR



Posts: 564
Joined: 7/28/2002
From: Sandy, OR,
Status: offline 		Very nice!

(in reply to Goinstraightup)
       Post #: 6

RE: Twin Otter Ready for a Swim - 5/3/2008 2:17:02 AM   
zeuglodon



Posts: 78
Joined: 6/22/2004
From: Howland, OH, USA
Status: offline 		So how'd it go, Hun? I have a set of floats I've been thinking about since last summer. I have an X9303 and was thinking of creating a "taxi mode" putting the throttles on the sliders on either side of the case....but i like your idea better. Let us know how it works out.

(in reply to N7OR)
       Post #: 7

RE: Twin Otter Ready for a Swim - 5/3/2008 4:00:46 AM   
vonJaerschky



Posts: 204
Joined: 8/25/2002
From: Comox, BC, CANADA
Status: offline 		It hasn't gone, yet! The weather here has been crappy, plus I'm not sure exactly where to give it a whirl the first time around. I will likely wind up waiting until the Chilliwack event and fly it at the float fly portion there. I have flown the airplane off wheels, and the differential throttle works really well. I can spin it around on a dime on the ground, so it should be fine on the water. I had a bit of fun in the air playing with the throttle, too. If you call sudden flat spins fun!

(in reply to zeuglodon)
       Post #: 8

RE: Twin Otter Ready for a Swim - 5/3/2008 4:12:06 PM   
vonJaerschky



Posts: 204
Joined: 8/25/2002
From: Comox, BC, CANADA
Status: offline
quote:

ORIGINAL: vonJaerschky

I've only tried floats once, many years ago, and it was a cold, wet, humbling experience involving the South Pacific, partial nudity, and hypothermia.


Just in case you thought I was kidding, here's a video of that attempt 12 years ago. Sorry for the quality, it was taken with a PAL 8mm camera, then put on a VHS, then converted to NTSC format, and now to DVD.

http://www.youtube.com/watch?v=RAKaYY3y_no

(in reply to vonJaerschky)
       Post #: 9

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