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Old Dec 07, 2011, 09:30 AM
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DoctorG's Avatar
United Kingdom, Basingstoke
Joined Nov 2011
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Hi Ian

I have used old Futaba 3001 servos.
I have ~ 15 throw on both elevators and rudder which gives adequate control. I estimate it has a flying speed of about 15mph and using a handy servo force spread sheet I have those deflections require a 'massive' 0.07 kg cm of torque. The 3001 has 3 kg cm... so a tadge in reserve.

In fact I was orginally going to put a 2/3 sized servo in the tail plane but then thought it might end up tail heavy so put standard servos and snakes in the conventional spot in the cabin area ...And then ended up putting about 4oz in the tail - equivalent to 6 servos of the size I was proposing! Ho hum.
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Old Dec 07, 2011, 08:26 PM
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Ian Easton's Avatar
United Kingdom, Scotland, Fife
Joined May 1999
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Thanks for the info DoctorG. My 9ft span Willis used "standard" servos which worked well but I always wondered about it regarding the forces involved. Seeing your numbers helps a lot.
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Old Dec 07, 2011, 11:15 PM
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Ian Easton's Avatar
United Kingdom, Scotland, Fife
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Brian,
Have you started on your falcon yet?

I got the brass wing joiner tubes with carbon rod installed tonight.

Found this tonight too...

Láďa Kulhavý ladí a startuje svého Falcona (0 min 52 sec)


It's the model from the link a few pages back, that no longer works.

Ian
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Old Dec 07, 2011, 11:49 PM
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Gold Coast Australia.
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I hate the way he's retching over the prop.
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Old Dec 08, 2011, 08:00 AM
Sic itur ad Astra
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United Arab Emirates, Abu Dhabi, Abu Dhabi
Joined Aug 2009
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Quote:
Originally Posted by gossie View Post
I hate the way he's retching over the prop.
yes it made me cringe a bit too gossie! lovely take off though!
sparks
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Old Dec 08, 2011, 03:12 PM
Sticks, Tissue & old Diesels
brokenenglish's Avatar
France, Centre, Amboise
Joined Nov 2011
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Quote:
Originally Posted by Ian Easton View Post
Brian,
Have you started on your falcon yet?

I got the brass wing joiner tubes with carbon rod installed tonight.

Found this tonight too...

http://www.youtube.com/watch?v=RUlNrs4sGpQ

It's the model from the link a few pages back, that no longer works.

Ian
Hi Ian,

I haven't actually started glueing wood together, but I'm "working" on it. In fact, I want to decide which engine to use before I start, which isn't really essential I suppose... However, I did some rpm tests on my Taplin Twin Mk II and, to be honest, I was a bit disappointed. I was only getting 5500 rpm on a 14x6 wood (see photo), although the handling, idle and consumption were great. Concerning the max. rpm, it's December and I suppose I may have got a bit more in summer weather. My best Drone (see photo) turns the same prop at 5150 rpm and it's only 5cc (but in warm weather). Within the next couple of days (I have a lot of work), I'm going to remove the timer assembly from the McCoy .60 (again see photo) and try it glow, with the Merco throttle grafted on. This engine has a fantastic idle on spark ignition. Otherwise, I have the choice of 2 or 3 Lasers (but they're modern!), or a several super old .60s (but they don't have a throttle!). Ain't life difficult...
Ian, what's all this nonsense about brass tubes and carbon rod? My plan doesn't show those!!!
I attach a photo of the kind of result I'm aiming for. This Falcon looks pretty authentic to me. The wheels are a bit cumbersome and plasticky, but the airframe is superb. It's not my plane unfortunately, I gratefully lifted the
photo from the SAM35 Web site.
Finally, it's just occurred to me that Eddie Keil's original Falcon flew with a very powerful Spark .60, and he didn't have a throttle... Maybe we're getting a bit soft...
Brian
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Old Dec 08, 2011, 09:24 PM
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Ian Easton's Avatar
United Kingdom, Scotland, Fife
Joined May 1999
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That is a great photo. As for brass tubes and carbon rods - well I don't have a lot of faith in the tongue and box affair shown on the plan - others have changed it too. I used the balsa spars per the plan but I did saw the upper spar down the middle and inserted a carbon fibre piece. I also attached a brass tube at the back of the two dihedral braces that carbon rods fit into, The front one is about 12" long (3/8" dia) and the smaller rear one is 8" long (1/8" dia) . Very strong and not much of a weight penalty. I've had wings fold before on other models and I'm making sure it doesn't happen on this one!
Great engines you have there. Mine will be powereed with a Magnum52 four stroke. I was considering electric but need to make use of my Magnum.
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Old Dec 16, 2011, 09:54 AM
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Oxford, UK
Joined Mar 2009
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Falcon progress

Work is slow. Wings took longer than expected especially sheeting the wings at the tips with compound curves. Bending with ammonia was a new learning experience. Forming sheeting over a leading edge.
Glued sheeting to the main spar.
Wetted the forward area with a 50 /50 mix of household ammonia and water, repeatedly, as it soaked in.
After 15 - 20 minutes or so when the sheeting became more flexible, two layers of handkerchief were laid on top, and with a hot sealing iron, coaxed the sheeting well over the leading edge. Worked well when grain was parallel with the LE. Not so easy when the grain direction was end on.
Then strapped the overhang in place with masking tape.
When perfectly dry, applied glue with a syringe (another first) and re-strapped the overhang in place again until set.
Another discovery was bending hard strip with it standing in the spout of a jug kettle with water boiling for about 15 minutes.
Another finding was about pushrods when linking the servos to the rudder /elevator horns with 2mm clevises.
UK model shops sell pushrods threaded 2mm at one end. When I measured the diameters of the rod stock and the threaded end, surprise! Rod dia. was 1.7mm and threaded end was 1.9mm. Yes, higher! The threads of model shop pushrods are not cut into the rod with a die but are made instead by rotating rollers around the rod, which raises a thread above the stock diameter.
A tool I was shown in a bicycle shop consisted of three rollers, each having a spiral cutting thread on the outside, like a screw, which were clamped, 3-jaw chuck style, to the rod end and rotated to produce a thread.
Because model shop pushrods are less than 2mm dia., using a 2mm die to cut a thread on them produces unsatisfactory results where clevises and 2mm nuts rattle loosely along the thread.
My pushrods were made from a 2mm bicycle spoke, using a 2mm die.
Progress with the tail was slow owing to the installation of the Hitec HS-82MG servos.

Thanks Ian for your selection of pictures of the fusalage build. They were a great help in my understanding of the one-dimensional plan. My next job in the New Year.

Best wishes to you all for Christmas and the New Year.
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Old Dec 16, 2011, 12:38 PM
I like real wooden aeroplanes!
Sundancer's Avatar
South-west France
Joined Sep 2007
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Really nice job on that tricky wing tip sheeting.
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Old Dec 17, 2011, 12:06 AM
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Ian Easton's Avatar
United Kingdom, Scotland, Fife
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Nice work there Ol Timer. I'm at the stage of putting the final sheeting on the wings too. I just put the sheet of balsa on the floor and spray the top with a lot of water, by the time I get everything else ready to go (glue the framework, get pins ready etc), the wood has develeoped a nice curve which makes it easy to go put in place and pin down.
I never thought of putting the servos inside the surfaces -that looks good.
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Old Dec 17, 2011, 09:31 AM
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Oxford, UK
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See this one in flight.
Ray

Falcon ve vzduchu a jde na finále...... (2 min 7 sec)
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Old Dec 17, 2011, 02:46 PM
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Ian Easton's Avatar
United Kingdom, Scotland, Fife
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There's a few Falcon shots here too. It looks like a nice day out to me...
Zlet historických modelov a II. Tomboy Session, SAM 122 (7 min 52 sec)
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Old Dec 17, 2011, 06:27 PM
The dog ate my clearance
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Joined Jan 2004
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Quote:
Originally Posted by Ian Easton View Post
There's a few Falcon shots here too. It looks like a nice day out to me...
What a great video clip. I hadn't expected such enthusiasm for vintage models in Eastern Europe. Thanks for sharing.

P
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Old Dec 18, 2011, 01:22 AM
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Ian Easton's Avatar
United Kingdom, Scotland, Fife
Joined May 1999
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What are you guys using in the way of wheels. I've been looking at the 4" to 6" range but some of them are a bit hefty in weight and price.
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Old Dec 18, 2011, 11:20 AM
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Tim Trick's Avatar
The Netherlands
Joined Apr 2004
593 Posts
Ian,

I eventually replaced the trexlers on mine with Kavan 125 mm light wheels. The weight increase was only a few grams and I did not have any further issues with type deflation.

Cheers

Tim
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