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Old Mar 10, 2003, 11:06 AM
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Athens, Ga, USA
Joined Jan 2001
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Ventus construction diary

Hi Everybody:

I am assembling Roedel’s version of the Ventus 2c. The wingspan is 4.8 m and projected weight is 5.5 kg. The plan is to make it convertible between aerotow and e-power, so wish me luck.

The wing is four-piece, with inner and outer ailerons, and top spoilers are included for glide path control. Six servos in the wings, 2 servos in the tail for rudder and elevator, and one in the nose for tow release. Guidance provided by Eclipse 7. I will see how well it flies, and if possible add a wheel retract. That will max out the radio.

I bought the kit from John Derstine (www.scalesoaring.net) at the Pensacola aerotow last month. He seems like a good guy.

I have built e-gliders from Graupner and Multiplex before. The fabrication in this kit is higher quality. However, the English instructions are minimal. The supplied hardware was in a plastic packet 2" by 2"! Fortunately, web resources offer a lot of construction alternatives.

I will post pics and urls as I go along. I want to finish this in time for the Fayetteville NC aerotow in May.
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Old Mar 10, 2003, 11:46 AM
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Athens, Ga, USA
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Here is what you get for $800. The fuselage is the longest component at 5' 8" so the plane can be transported in a small car. The fuse is gelcoated fiberglass, and the wings, rudder, etc are obechi over foam cores. That black tube is the wing joiner, steel 20mm and weighs about 1.5 pounds.
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Old Mar 10, 2003, 12:44 PM
luc
I plant balsa sticks too
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France
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ventus/ Nimbus

You can look at my Nimbus 4DM which has roughly the same characteristics: 5m20 for 5kg
http://www.geocities.com/lucchev/ (link at the bottom)
As stated, I epowered it by an HP 220/30 A3 P4 5:1, which should be able to lift around 9kg sailplane

If you want to gain some weight start by replacing your steel bar by a carbon one, you will gain more than a pound.
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Old Mar 10, 2003, 06:48 PM
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The first step is gluing the provided plywood plate into the tail fin, on the underside of where the stab will sit. You just sand it down to a close-fitting V shape. Tape the open end where the rudder will be so the glue doesn't dribble out. Pour in the epoxy and set the plywood in.

The stab is already drilled for the mounting bolts, so your options for positioning the stab on the fin are +- 5 mm. Being a risk taker, I chose the middle. Mark and drill the holes, then tap them. This picture shows the inside of the fin (upside down) with the plywood and nylon bolts installed.
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Old Mar 10, 2003, 07:31 PM
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Here is a scan from the instructions showing one of two options for the tail controls. The first option has the servos near the nose. I chose this option B to offset the weight of the motor and batteries. The elevator servo is a HS-5125MG, and the rudder is a HS-85MG.

Starting with the elevator, I will shrink wrap the servo, then glue it into the stab, so I have options if the servo has to be serviced. Piano wire linkage and two clevises will connect the HS-5125MG to the elevator horn.

Next, the rudder.
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Old Mar 11, 2003, 11:14 PM
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That scan from the instructions is what you might call "stylized." On this plane,the elevator control horn is well inside the stab and the rudder is pretty square, not shaped like they show.

I was ready to Goop the shrink-wrapped elevator servo into place. But it occurred to me, once the rudder is in place, the linkage to the elevator will be inaccessible. Removing the stab would be impossible.

I could do some serious cutting of the rudder, but that wouldn’t look scale at all. Or, I could make the rudder removable. Robin Lehman has a web page on how to do this at http://www.sailplanes.com/Tips/Rudde...stallation.htm This might be the best option.
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Old Mar 12, 2003, 10:38 PM
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Talked on the phone today with John Derstine. He says that a removable rudder is usually a good idea, so I will go that route.

Here is a pic of the tail setup after I taped components together to see how it all fits. On the top, rear of the fin there are incised marks at the corner on both sides. You have to saw off the fiberglass along these marks for the elevator to move down at all. No problem, but I wonder why the instructions didn't mention it. Oh well, it's pretty obvious.

The instructions should also say that the rudder leading edge has to be flush with the fin's trailing edge. If the rudder is mounted recessed into the fin at all, it won't clear the V you see in the elevator.

That routed plywood you see in the middle is the tail post. John says this has gotta be glued in, as is, to give the fin sufficient strength. I was tempted to try something different - bad idea.

I had the elevator servo Gooped in, but I wasn't happy with the position so I followed the Goop instructions and used a putty knife to remove the servo from the fin. It came out, along with a layer of fiberglass! No kidding, the fiberglass came off easily, still attached to the shrinkwrap on the servo. Looks like in this case, Goop is incompatible with fiberglass. I will stick with using 30 minute epoxy in the future.
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Old Mar 14, 2003, 10:25 AM
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Began working on the wing. That blue tube sticking in the wing root is the joiner sleeve. I cut it to length, then sealed it with expoxy to prevent the joiner from getting glued in there later on.

The intsructions say you have to drill out the fuselage wing root fairing to accept the joiner tube, but I didn't. The joiner holes were molded into the fuse, and there's just a little fiberglass left to cut out with an exacto. The two joiner holes lined up pretty closely. To get it perfect I wrapped sandpaper around a smaller diameter tube and removed a little gelcoat until the joiner tube slid through both holes.

The 20mm steel wing joiner was about 1" too long, so I cut it with the Dremmel tool.
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Old Mar 14, 2003, 02:30 PM
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Quote:
Originally posted by WarrenKriesel
The 20mm steel wing joiner was about 1" too long, so I cut it with the Dremmel tool.

Wow, that sounds easy!
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Old Mar 14, 2003, 03:20 PM
MTT
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It is, with the little cutting wheel from Dremel.
I have done so myself, although it was "only" a 12mm steel joiner.
Used up 3 or 4 of the little cittung discs in the process.

Michael
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Old Mar 14, 2003, 08:52 PM
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Yeah, I should give more details about the joiner. It is like a pipe, with outer diameter of 18mm and inner diamter of 14mm, and is 22 1/4 inches long (56.5cm).

I cut it with one wheel and 5 minutes of time. But it is not light, and if I were walking around our fair city after the bars closed, I would want to carry this as personal protection.

Warren
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Old Mar 14, 2003, 09:10 PM
MTT
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Warren, if you ever fell the need for lightening the Ventus, check with Capn Crunchie, for a steel joiner rod with "carbon filling "

==> see the thread about the DG-505 here on E-zone, in the scale sailplanes forum.

Since I want to convert my Multiplex ASH 26 to up&go power, I was looking for ways to lighten up the airframe, to compensate a bit for the weight to be added by the drivetrain and batteries.

He supplied me with a 12 mm steel/carbon joiner, which saves almost 200 g ( 7 oz. ) ! It consists of a 12 mm steel tube with 1 mm wall thickness, in which a carbon rod is installed ( with epoxy, I guess )

Michael
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Old Mar 14, 2003, 09:23 PM
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Yup, I have had the very same thought. Light planes always fly better. Monsieur Luc mentioned the CF option too.

However, I took a course in ag engineering about 25 years ago, and the only thing that has stuck with me is: don't try to out-smart the designing engineer.

I think that in the case of a 4.8m wingspan, I'll test fly it with original equipment, and go to CF if it will stand it. The CF diameter is smaller, so retro fitting would be easy.

Warren
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Old Mar 14, 2003, 09:33 PM
MTT
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Warren, you have a point, but on the other hand, I think that the wing joiner on my ASH26 as well as on your Ventus are way oversized.
I mean, think of the force required to bend/break a 12 mm ( or 14 mm, in your case) solid steel rod !

I think that if you manage to put a load on the airplane big enough to damage the wing joiner , something else will give long before that.

Michael
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Old Mar 14, 2003, 09:37 PM
MTT
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West Chester, Ohio
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Warren just read your post about the joiner again, and am not sure now : Is your joiner rod solid or hollow ?

On the picture it looks like it were solid.

Michael
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