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Old Nov 04, 2013, 10:26 AM
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Tucson
Joined Nov 2009
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Silence Twister, Seagull

I'm having trouble finding info on this ARF. Feel free to leave your comments here on how you are flying yours, or building info.

What I am looking for in this plane:
Aerodynamic cross section, smooth aerobatic flight, good amount of wing, larger tail area than a scale Spitfire, at least 12 minutes flying time. Good looking color scheme that has clear up-down color differences. Long enough nose so that a gas engine will not need extra weight to make CG.

Initial comments on the ARF:

- just over $200 + shipping
- Beautiful fared body, nice color scheme (white on top, gold and white checker on the bottom), 66.9" wingspan, gorgeous elliptical Spitfire wing, horizontal tail that has a large span (25").
- body is nicely laser cut light ply, with nice insets for the plug-in wings.
- LED wingtip lights
- included metal retracts (I will fly fixed gear) that fold back
- large split flaps that work without binding
- large, single compartment in body in front of wing tube (nice layout)
- large top hatch in the style of electric planes: I strenghtened the rear cockpit wall, and rebuilt the front pegs

Planned setup:
- 20cc gas DLE engine
- 24 oz gas tank
- 110 oz-inch servos for regular control surfaces (Solar)
- 80 oz-inch servos for flaps
- no LED connection

Building notes:
- good quality build manual
- firewall is thick, but only 1/2 supported (would not work for gas engine). Used 1/2" maple square sticks to epoxy around the back of the firewall, and 2 longer ones from the top of the firewall back down to under the wing tube, attaching to the sides of the gas tank compartment.
- cut out the hatch to fit a 24 oz gas tank
- made new hatch CF pegs, as maple reinforcement gets in way of the original
- tail feathers are set up for push rods (split elevator). Although rudder control horn is pull-pull. Push rod plastic tubes a already installed, so I went with the pushrod rudder.
- tail wheel hardware was a mystery - with a masters in science degree I could not figure out how the hardware would create a steerable tail wheel. I went with another wire setup, with wire pull-pull from rudder
- horizontal tail has only a narrow connection to fuselage. I put a solid sheet across the fuselage under the tail for better epoxy connection.
- will try mounting the DLE 20cc using the 1.20 template included

That's as far as I have gotten on the build.
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Old Nov 04, 2013, 07:20 PM
Registered User
Tucson
Joined Nov 2009
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I put a 1/2" maple stick behind the tail wheel, with a balsa glued to the rear side to accept the CG hinge for the rudder. Installed the post and the hinge at the same time.

The wing locking system is not described in the manual (I think). A metal rod screws into the plastic threaded receiver in the fuselage. The other end fits into the wing and into a hidden clamp. (Not in the manual, I think.) Turn the mechanism through a hole in the bottom of the wing, until the metal post slips in. Turn the mechanism so that it locks the wing on. A large screw driver will turn the mechanism.

A complication was that the right wing locking mechanism was not quite lined up correctly with the wing tube. The right wing will only lock on without the wing tube in (rotate the wing slightly until the post slips in. Lock it, then slip the wing tube in). After 30 minutes of hinking around, I got the 2 wings to lock on.

Finish is "B" quality. Covering will (almost) snap tight with hot heat from a blow drier. But some small wrinkles will not even out.

Even with these diversions, I consider the ARF to be a good buy.
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Old Nov 06, 2013, 09:18 AM
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Tucson
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Rudder control rod is a straight shot, and works without binding. Elevator (dual) control rods need relaxed Z bends outside the body, or else the rod bending outside the fuselage will cause a lot of binding.
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Old Nov 07, 2013, 10:19 AM
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Keller, TX
Joined Aug 2005
299 Posts
Just curious..,.why a 24 oz fuel tank for a 20cc gasser? Duration flying? Fuel consumption for a 20cc gas engine is comparable to a .46 glow engine. I run 8oz tanks on my 20s for 10- 12 min flights, but not full throttle all the time. 24c oz fuel means you are hauling extra cargo for most of your flying time.
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Old Nov 08, 2013, 10:11 AM
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Tucson
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I just started to fly gas engines this year. When I started, I flew a 30cc engine with the (supplied) 10 oz tank in the ARF. I ran out of gas, and bushed the plane in a landing pattern. Since then, I put as large a tank as I can in a plane, and don't worry about running out of gas. Even if you only fill it 2/3, that is only a pound.

At Tucson elevation, I may only get 10 lbs of thrust out of the DLE 20cc, so I will have to see whether it can do vertical aerobatics with a full tank.
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Old Nov 08, 2013, 10:14 AM
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Tucson
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Retracts are nice quality. The plane will look like a war bird with them.
Rubber mountings for the servos are not supplied - I suppose that the expectation was for the ARF being fitted as electric.
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Old Nov 08, 2013, 06:13 PM
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Keller, TX
Joined Aug 2005
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Quote:
Originally Posted by wuest3141 View Post
I just started to fly gas engines this year. When I started, I flew a 30cc engine with the (supplied) 10 oz tank in the ARF. I ran out of gas, and bushed the plane in a landing pattern. Since then, I put as large a tank as I can in a plane, and don't worry about running out of gas. Even if you only fill it 2/3, that is only a pound.

At Tucson elevation, I may only get 10 lbs of thrust out of the DLE 20cc, so I will have to see whether it can do vertical aerobatics with a full tank.
A practical "rule of thumb" for small 2 stroke gas engines is that engine displacement = 1 minute of run at full throttle. This is subject to variables such as state of tune of the engine, prop selection, flying style, etc.

20cc = .68 oz
30cc = 1.01 oz

24 oz tank should be good for nearly a half hour at full throttle with the 20cc.

Enjoy!
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Old Nov 08, 2013, 06:30 PM
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Traverse City, Michigan
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I tend to agree. That's a large tank for a small engine.
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Old Nov 08, 2013, 06:56 PM
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So, I'm wondering if it's a "scale" model?

Not trying to be the forum police, here. Just think it possible that more appropriate answers might be found in ARF threads.

I am willing to be educated.
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Old Nov 09, 2013, 06:46 AM
ARFs Are Me
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Traverse City, Michigan
Joined Dec 2005
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Quote:
Originally Posted by packardpursuit View Post
So, I'm wondering if it's a "scale" model?

Not trying to be the forum police, here. Just think it possible that more appropriate answers might be found in ARF threads.

I am willing to be educated.
I was wondering the same thing.

I looked it up, but couldn't find much.
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Old Nov 09, 2013, 09:49 PM
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Keller, TX
Joined Aug 2005
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Silence Aircraft GmbH is the German mfg of the Silence Twister, a single seat home built kit plane.

see specs at http://silence-aircraft.de/en/aircraft/specs/
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Last edited by RCFVR; Nov 10, 2013 at 06:36 AM. Reason: correcting typo
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Old Nov 10, 2013, 06:25 AM
ARFs Are Me
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Traverse City, Michigan
Joined Dec 2005
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Quote:
Originally Posted by RCFVR View Post
Silence Aircraft GmbH is the German mfg of the Silent Twister, a single seat home built kit plane.

see specs at http://silence-aircraft.de/en/aircraft/specs/
Thanks !

I hadn't heard of this airframe, previously.
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Old Nov 10, 2013, 09:39 AM
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Tucson
Joined Nov 2009
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Thanks for the gas tank comments. It's definitely not a standard approach, but I had 4 x 24 oz tanks sitting around, and it does negate the complication of using a timer on the radio.

(RCFVR) I'm trying to think through the comments on gas usage in 2-stroke engines and displacement. The numbers that I came up earlier this year (as to displacement) are:

20 cc = a cube with 2.71 cm on a side ( a cube root of 20.0)
= a cube with 1.05 inches on a side
= a 1.05 cubic inch engine

30cc = a cube with 3.1 cm on a side (a cube root of 30.0)
= a cube with 1.2 inches on a side
= 1.73 cubic inches

A .90 cubic inch engine = a cube with 0.965 inches on a side
= a cube with 2.47 cm on a side
= 15.069 cc

Does the rule of thumb mean that the engine will use as much gas per minute of full throttle as the displacement in cubic inches, or the displacement in the equivalent number of liquid ounces?

If cubic inches, then:
24 oz tank / 1.05 cubic inches displacement = 22 minutes of flight for a 20cc engine
24 oz tank / 1.73 cubic inches displacement = 13 minutes of flight for a 30cc engine.

I usually fly until I feel like landing, which leaves about 1/3 tank of gas, and no problem of sucking air on the landing approach....

Granted, practicing low speed aerobatic maneuvers will greatly extend flight time. But most fliers of warbirds tend to go full out all the time.
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Old Nov 10, 2013, 09:42 AM
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For those who have not heard of the Silence Twister, I chose this ARF because of the elliptical Spitfire wings, enlarged tail surfaces for control, and the fact that this full-size plane was built first as an RC model (and flew so well that it was made into a full-size experimental).

I wanted a Spitfire-like smoothness, with improved aerobatics. An interesting combination in a scale model.
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Old Nov 10, 2013, 09:52 AM
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Tucson
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Update on the build....

Went out yesterday to run in the engine, and had a dead ignition unit. (Doesn't DLE check this in the factory? No spark.) I didn't think to check this at home, because I assumed that quality control at DLE would catch this.

Problem: during the handling with wings on, debugging the ignition, one of the wing connectors unhooked. The connectors seem to be furniture connectors, and I had had trouble opening and closing them with a screw driver. They are so twitchy to open and close with a screw driver, that I will think of another way to connect the wings -- I don't consider them reliable, and don't want to lose the plane in flight. (I read the manual, and didn't notice anything in it about how the wings were to be clamped on. This is a documentation oversight.)
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