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Old Dec 01, 2012, 09:34 PM
Silent Flight
Twyl's Avatar
United States, CA, Cypress
Joined Jul 2005
3,951 Posts
Quote:
Originally Posted by bonnie9496 View Post
Thanks guys for the feedback..

Repairs to fuse effected and the Speedo looks good again.
Have lessened the elevator throws to 3mm up and down.
Checked the CG and It was back at 81mm. Hmmmmmm and I flew so well? Just not aerobatically. Adding more weight to nose to get it to 70mm mark. Will then report back after next flight.
Hey Bonnie, we aren't saying your CG was off. Just do the dive test to determine how it reacts. Even the same make of plane can have slightly different CGs depending on the exact one you got and other unique traits that makes your plane your plane. I'm with Cory and fly with a CG around 78-80. If you were flying fine at 81mm I doubt you'll be happy at 70mm, but regardless,... do the dive test.

If you were going with >3mm elevator travel with a far rearwards CG I think we can say that was probably your issue with the loop failure. I'll let other figure out your roll issue as I'm not sure on that.

-Jonathan
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Old Dec 01, 2012, 09:46 PM
I DS slower than I build!
Cory's Avatar
Idaho Falls
Joined Jul 2006
2,350 Posts
Quote:
Originally Posted by bonnie9496 View Post
Thanks guys for the feedback..

Repairs to fuse effected and the Speedo looks good again.
Have lessened the elevator throws to 3mm up and down.
Checked the CG and It was back at 81mm. Hmmmmmm and I flew so well? Just not aerobatically. Adding more weight to nose to get it to 70mm mark. Will then report back after next flight.
I wouldn't move the CG that far forward. The plane is very stable at 80mm. It will probably be fine at 81 with appropriate throws. Mine very slowly pulls up when placed in a 45 degree dive, which indicates that the CG is still a little ahead of the neutral point. It's far enough ahead that the plane flies very well hands off in all but the worst turbulence. Launches in 40 mph winds are not scary. I launch right handed and it just tracks straight out while I'm trying to get my thumb on the stick.

The key is not having excessive elecator throw. If you go with 3mm on high rates and 2mm on low rates with a CG between where you have it and 75mm you'll be fine.
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Old Dec 02, 2012, 04:14 PM
The SteamRoller
USA, CA, Fort Bragg
Joined Oct 2009
372 Posts
I love RC'ers! All the help we give one another! Makes me smile!
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Old Jan 25, 2013, 03:46 AM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
New Zealand
Joined Feb 2010
558 Posts
Aileron control horn

Hi All
I'm on the last stages of building a Speedo and just have a question about which hole on the supplied aileron horn everyone is using? As the manual (thanks Stunt Double!) calls for 6mm from aileron surface I'm thinking the middle hole (like the elevator) would be best? Looking at the aileron throws a bit of 'gearing up' would be the go.
Cheers
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Old Jan 25, 2013, 04:34 PM
I DS slower than I build!
Cory's Avatar
Idaho Falls
Joined Jul 2006
2,350 Posts
Mine's in the middle hole.
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Old Jan 26, 2013, 01:10 PM
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Woodstock 1's Avatar
Ireland, County Kerry, Kerry
Joined Dec 2005
6,994 Posts
For some reason or other mine's in the outer holes. But, that all depends on the length of your servo arms, doesn't it? I think in my case I have longish servo arms in order to clear the bottom of the wing with the linkage...

Chris
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Old Jan 26, 2013, 01:31 PM
Silent Flight
Twyl's Avatar
United States, CA, Cypress
Joined Jul 2005
3,951 Posts
When speaking of just "Aileron horn" you are also forgetting the servo horn since it is a combination of the two which give you your throws. By using the closest hole on the servo and the farthest hole on the aileron horn you are utilizing the best mechanical advantage and also the highest resolution when talking about control surface centering. Conversely this will give you the least amount of aileron movement.

In my opinion, if you are unsure what to do, then this is the best place to start. Once the linkage is setup, test it and measure how much it compares to throws suggested in this manual. If the throws are too much, then reduce the throws in your Tx settings, if the throws are not enough, first try to increase the throws in your Tx setting, if that is still not enough then move the linkage on the aileron horn down one notch and retest.

That is the simple explanation, but note that there are other adjustments that can be made within your Tx depending on how the servo horn is installed onto the servo when it is in neutral. A good example of this would be how flap servo linkage is installed on bigger gliders but a version of this method could be used for aileron servos when you consider in differential. Ignore this paragraph though until you've exhausted other options as I'm just trying to point out there are still other ways to tweak linkage.


-Jonathan
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Old Jan 26, 2013, 01:34 PM
Registered User
USA, CA, Pismo Beach
Joined Oct 2007
1,409 Posts
Yeah, you need to consider both the hole locations on the servo arms as well as the control horns in order to get the surface motion you need - of course consistent with clearance requirements for unobstructed motion of all the moving parts.
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Last edited by Greywing; Jan 26, 2013 at 01:36 PM. Reason: Johnathan beat me to it.
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Old Jan 26, 2013, 02:47 PM
Registered User
United States, CA, Camarillo
Joined Jan 2005
763 Posts
Servo/Surface Travel

If there is any slop at all where a clevis or Z-bend bears in a hole in either/both the servo arm or surface horn it becomes proportionately less in relation to ultimate surface travel the further out on arm or horn it is installed. So less dither is seen in the control surface movement when using an outer hole than when using a hole nearer center.

I always try to contain control travel first mechanically vs. limiting it by reducing travel in the transmitter "end point" program adjustments. This because most tx's simply reduce the number of total available "steps" out of 2048, 1024, 512 or whatever their max to clip the total travel & they don't cram the total bit count into a smaller output span.. This coarsens the effective resolution from stick to surface. If you are just slightly long on travel & the next hole combo down gives less surface travel than what you need then a little tx travel reduction is the way to go.

Another thing the tx manufacturers often don't tell you is that a trim change within a programmed travel range not only moves the center trim point but actually shifts the end-of-travel points, both in the same direction as the trim point moves. So the whole range moves as a sliding "window" one way or the other, following trim. If you are up near a mechanical travel limit & then re-trim in that direction you can jam the end with the increased travel up against it. So you always need to allow some margin in max mechanical travel to account for later trim changes.

It's possible that some of the flood of new tx's may have resolved these trim, travel & resolution anomalies but I use only older programmable tx's & just work around them. Would be interested in new info. When I asked Hitec about it a few years ago in the case of the then new Aurora, I don't think they quite understood the question.

Richard
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Old Jan 26, 2013, 03:24 PM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
New Zealand
Joined Feb 2010
558 Posts
Wow that question kicked this thread into life for 2013! Happy New Year everybody!

Agree with what has been written in reply. Fairly obvious it's a two-arm relationship, sometimes it's just easier to ask those that have gone before rather than figure it out from scratch (lazy ). Have gone for the middle hole, with the servo arm on outer. I'll give more precise measurements later (for the record) when I fully wake up With the aileron arm in the middle hole I get good aileron movement so all good. With hole selection, as written above and in summary: its a compromise between control-surface range Vs resolution.

Actually after reading through the Speedo threads I've brought the elevator servo horn towards centre one hole - seems this bird needs very little elevator movement so might as well increase the resolution of the elevator throws.

Also am using my ER9x TX firmware to program TX throttle-stick for variable spoilerons (with elevator compensation mixed in). I read this bird comes in fast for a landing

Edit: Pardon me, forgot to say - thank you all for the replies!
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Old Jan 26, 2013, 03:45 PM
Silent Flight
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United States, CA, Cypress
Joined Jul 2005
3,951 Posts
Quote:
Originally Posted by argo-2 View Post
Actually after reading through the Speedo threads I've brought the elevator servo horn towards centre one hole - seems this bird needs very little elevator movement so might as well increase the resolution of the elevator throws.
Very true, but also dependent on where you have the CG set. With a more rearward CG setting less elevator movement is needed, but in general, going with tighter resolution, assuming linkage is able to move freely and not binding, is a good thing to do.

Quote:
Originally Posted by argo-2 View Post
Also am using my ER9x TX firmware to program TX throttle-stick for variable spoilerons (with elevator compensation mixed in). I read this bird comes in fast for a landing
"comes in fast" is rather dependent on the eye of the beholder and how it is flown and what kind of landing approach is required for the slope. While many have used spoilerons on the speedo with varying degrees of success, I've never done so and never really felt the need for it, but go for it if you feel the need.

-Jonathan
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Old Jan 26, 2013, 04:36 PM
Multi Rotor Maniac
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Australia, VIC, Melbourne
Joined Oct 2007
2,880 Posts
Good to see this thread is still alive! Personally I try to get as much throw as physically possible on both the ailerons and elevator then add about 50% expo. With big elevator throw the Speedo can be flicked around to perform tight loops. Certainly wouldnt recommend a beginner to start off with this much travel but once you have a feel for the plane you can push the limits.
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Old Jan 27, 2013, 04:36 AM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
New Zealand
Joined Feb 2010
558 Posts
Good info thanks Twyl/SD

Another question: Any reported Horiz-stab/Wing incidence problems?
Just wondering how good the R2 molding is?
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Old Jan 27, 2013, 04:48 AM
Silent Flight
Twyl's Avatar
United States, CA, Cypress
Joined Jul 2005
3,951 Posts
You should always double check your incidence. The slot for the horizontal is typically wide enough for play so depending how you glue it in you could be giving it different incidence.

-Jonathan
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Old Jan 29, 2013, 07:17 PM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
New Zealand
Joined Feb 2010
558 Posts
Nope no play in my slot (don't ever Google that phrase )! I would say it's perfectly sized. Actually did some reading on decalage. If its out slightly the elevator will compensate. Sure this adds drag but as I won't be thermalling, no problemo.

Also came across an interesting article called "Gordy's Travels #1, Gordy's Sailplane Balancing System". Not everything he writes I agree with (but most things do seem very sensible). Key learning for me, with regard to this thread, is why moving the CG back reduces the required elevator throw's...simply put: moving CG aft is better balancing your Speedo, so the elevator has more effect at a given airspeed. This very much fits with those at ~80mm CG and 2mm Ele travel, versus: 65mm CG and requiring gobs of travel. Its a good read (after you get over the fact he calls the 'Dive Test': "...the dumbest thing anyone ever came up with for checking balance"

So reckon I'll start at a CG of 78mm and go from there. Now if only my aileron servos would get here!
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