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Old Feb 28, 2012, 10:25 PM
Fly like you can still see it
Dave Garwood's Avatar
USA, NY, Schenectady
Joined Mar 2009
127 Posts
Gerasis DG-800 control movement specs

Quote:
Originally Posted by bie View Post
Hi,
donít worry, I can confirm: The stab definitely works as it should (at least it did in the last 15 years)Ö Andy
Andy,

If I recall correctly, you said the Gerasis DG-800 was one of your 2-3 top favorites out
of 50 planes you have built and flown. That observation gave me a lot of confidence
as I began building this kit.

However, I do not have the instructions, so I ask your advice on control surface throws.

My ailerons move UP 17 mm and DOWN 12 mm as installed now.
In your experience, is that enough aileron movement?
Is that enough aileron differential?

// Dave
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Old Feb 28, 2012, 11:58 PM
more casual than stylish....
slopemeno's Avatar
Joined Jan 2003
6,949 Posts
My Gerasis DG-800 flies fine, small stab and all.

Not much to tell, really. It thermals surprisingly well, and is very stable. It makes nice fast carving passes at the slope, loops amazingly well (great energy retention over the top) and can be rolled fairly easy for a scale plane.

On the spoilers, mix 5% up elevator on your landing mix. It slows down if you give it a moment, and you can really slide in on the landing.

On your aileron throws, that sounds like more than I use. I'd set up some dual rates. I have my rudder mixed in with my ailerons so thermal turns are low effort. My suggestions would be to leave your rates mix open on your radio when you maiden it, and season to taste.

Question: What did you do for an elevator servo? I had a bunch of double centering with the stock elevator snake, so I finally got frustrated enough to remove the rudder and post, and mount a JR-341 servo inside the vertical stab. I made the shortest-possible
servo output arm and a very short pushrod up to the elevator. Works *perfect*.
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Last edited by slopemeno; Feb 29, 2012 at 12:05 AM.
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Old Feb 29, 2012, 09:13 AM
Fly like you can still see it
Dave Garwood's Avatar
USA, NY, Schenectady
Joined Mar 2009
127 Posts
Very fine starter white wing kit for Dave

Quote:
Originally Posted by slopemeno View Post
My Gerasis DG-800 flies fine, small stab and all.

Not much to tell, really. It thermals surprisingly well, and is very stable. It makes nice fast carving passes at the slope, loops amazingly well (great energy retention over the top) and can be rolled fairly easy for a scale plane.
slopemeno,

Thank you for the flight report and setup tips.
Looks like I found a very fine starter scale kit.

Love your NorCal travel and slope flying location reports.
I have flown at Goat Rock. You make me want to fly at Navarro Bluffs County Park.

I agree with you on the ZIPPER and Bowman's COMANCHE.
Photo of Dave at Davenport with COMANCHE - same trip as Goat Rock trip.
We got a lot of flying time with the DAW 1-26s from pullouts along the PCH.

Ah, the memories come flooding back.
// Dave
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Old Feb 29, 2012, 10:33 AM
more casual than stylish....
slopemeno's Avatar
Joined Jan 2003
6,949 Posts
If I can I'll assemble the DG-800 tonight and give you my throws. It flies like a big 60" racer- like a Sparrow or Fun-1, in my opinion.

Yeah, we're lucky. It's expensive as all get out to live here, but the flying makes up for it.
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Old Feb 29, 2012, 05:04 PM
Fly like you can still see it
Dave Garwood's Avatar
USA, NY, Schenectady
Joined Mar 2009
127 Posts
DG-800 throws

slopemeno,

>If I can I'll assemble the DG-800 tonight and give you my throws.

Any time in the next week works for me. Thanks.

> It flies like a big 60" racer- like a Sparrow or Fun-1, in my opinion.

Man-o-man, this is music to my ears.

// Dave
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Old Feb 29, 2012, 06:29 PM
Fly like you can still see it
Dave Garwood's Avatar
USA, NY, Schenectady
Joined Mar 2009
127 Posts
Short elevator linkage

Quote:
Originally Posted by slopemeno View Post
Question: What did you do for an elevator servo? I had a bunch of double centering
with the stock elevator snake, so I finally got frustrated enough to remove the rudder
and post, and mount a JR-341 servo inside the vertical stab. I made the shortest-possible
servo output arm and a very short pushrod up to the elevator. Works *perfect*.
I had been reading about elevator centering problems and I decided to discard the snake
and put the elevator servo in the tail. I spent lots of time figuring how I mount it inside the
vertical, but I was not happy with any linkage I could think of, so I decided to mount it in
the elevator. How's this for a short linkage?

// Dave
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Old Feb 29, 2012, 09:42 PM
more casual than stylish....
slopemeno's Avatar
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There you go- that's as short as possible. I have a Spectrum that I want to try that on.
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Old Mar 01, 2012, 05:48 AM
bie
maidenflight-postponer
bie's Avatar
Germany
Joined Oct 2004
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Hi Dave,

Quote:
Originally Posted by Dave Garwood View Post
However, I do not have the instructions, so I ask your advice on control surface throws.

My ailerons move UP 17 mm and DOWN 12 mm as installed now.
In your experience, is that enough aileron movement?
Is that enough aileron differential?
since the DG-800 is dismantled right now for renovation purposes (there are some cracks in the fuselage and I have to reinforce the fuselage) I can’t measure the aileron movement right now, sorry!

But I second Slopemeno’s remarks regarding this topic.

You’re servo installation of the elevator-servo makes me envy you! Perfect!

Do you want to fly on slopes? If so, do you expect rough landings? If so, I have to tell about a not so perfect landing with the DG-800 I had some years ago at Hahnenmoos Pass in the Swiss Alps: It was pretty rough and on first - hmmm - impact (it still was a "landing" after all, because no part of the plane separated from each other ) the horizontal stab broke right in the middle above the rudder fin!

Why do I tell? You’re servo brings in some additonal weight to that relatively delicate part of the plane. I had to reinforce the stab with an additional spar (made of balsa) - maybe you might want to do the same...

Andy
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Last edited by bie; Mar 01, 2012 at 05:58 AM.
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Old Mar 01, 2012, 07:58 AM
Fly like you can still see it
Dave Garwood's Avatar
USA, NY, Schenectady
Joined Mar 2009
127 Posts
Reinforce the horizontal stab, and the elavator

Quote:
Originally Posted by bie View Post
Youíre servo brings in some additonal weight to that relatively delicate part of the plane. I had to
reinforce the stab with an additional spar (made of balsa) - maybe you might want to do the same.
Andy
Good advice. I will reinforce the reinforce the stab.
I was thinking also of strengthening the section between the elevator halves.

Thank you.
// Dave
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Old Mar 01, 2012, 08:27 AM
MTT
I care about rising air !
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West Chester, Ohio
Joined Feb 2002
2,012 Posts
Agree with all the previous posts...
Placing the servo in the horizontal stab will cause a lot more stress on the vertical fin on rough landings...
Instead of operating on the vertical fin to reinforce it, I recommend you install the elevator servo somewhere in the bottom of the fin, with a short pushrod to the elevator.
another possibility :
Install bellcrank in the fin, the servo in the fron of the fuselage, and connect it to the bellcarnk with a bowden type pushrod.
since it will be an almost straight line from the servo to the bellcrank, there should be no issues with binding or centering.
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Old Mar 01, 2012, 09:26 AM
bie
maidenflight-postponer
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Germany
Joined Oct 2004
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David,

Quote:
Originally Posted by Dave Garwood View Post
I was thinking also of strengthening the section between the elevator halves.
thatís the way to go, if you want to keep the servo in the stab - or either follow the direction, that Michael suggests.

In my DG-800 the elevator-servo is built into the upper half of the fin.

Andy
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Old Mar 01, 2012, 11:52 PM
more casual than stylish....
slopemeno's Avatar
Joined Jan 2003
6,949 Posts
I actually had the same issue a few years ago- hard to believe I've had that DG since 2000...


I was flying at Fourcorners in Marin County, and seeing just how far/high I dared fly away (high enough that Sean Sharif said, very deliberately "Don't...take...your...eyes...off...of....it." ) and decided to make a huge screaming pass. Flew past and landed and half the horizontal stab was hanging down about 20 degrees. Maybe I pulled up a little hard on that pass.

I stripped the covering, and the stab is covered in some paper-thin balsa. I repaired the break with a couple of layers of 3/4 oz E-glass cloth, and recovered the stab. No problems since.

A gunsmith friend of mine made the bellcrank that's inside the elevator. It's similar to the Brodak control line flap/elevator bellcranks, but the horn is oriented at 0 degrees to the tips.
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Old Mar 03, 2012, 05:06 AM
Pat Chewning
USA, OR, Beaverton
Joined Sep 2009
318 Posts
What size is that joiner rod, and how much does the plane weigh?
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Old Mar 03, 2012, 06:09 AM
Life-abstract=conformity
S.F. Bay Area
Joined Aug 2002
1,879 Posts
Quote:
Originally Posted by Dave Garwood View Post
Andy,

If I recall correctly, you said the Gerasis DG-800 was one of your 2-3 top favorites out
of 50 planes you have built and flown. That observation gave me a lot of confidence
as I began building this kit.

However, I do not have the instructions, so I ask your advice on control surface throws.

My ailerons move UP 17 mm and DOWN 12 mm as installed now.
In your experience, is that enough aileron movement?
Is that enough aileron differential?

// Dave
Hey Dave,The 800 looks great! I think we all would like to see more picts.
My MPX DG600 is @ 3.6m span so should be close to your 800.
I've attached the setup from MPX to get you started.When I setup my DG-600 accordingly it was just Fab.
Skies.
Jay
P.S. My H-stab measures just over 25-1/2" & 4-5/8" chord (w/elev.)
For pchewn, the DG-600 wingrod is 12mm X 300mm. How does that compare to yours Dave?
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Last edited by AirBornOne; Mar 03, 2012 at 06:26 AM.
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Old Mar 04, 2012, 10:25 AM
Fly like you can still see it
Dave Garwood's Avatar
USA, NY, Schenectady
Joined Mar 2009
127 Posts
Quote:
Originally Posted by pchewn View Post
What size is that joiner rod, and how much does the plane weigh?
pchewn,

My wing rod is 10 mm diameter, 300 mm length. Made of steel.
Let give you the weight when I get nose weight and fuselage servos installed.
Preliminary balance test indicates I need about 17 ounces of nose weight.
I just glassed the inside of the front compartment. That added 2.2 ounces.

// Dave
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