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Feb 19, 2016, 12:23 AM
Registered User
Thread OP
Question

RDS, LDS surface drive system opinions.


I'm looking for opinions on the various rotary and linear surface drive systems used on current top end F3B gliders. It seems many builders use their own technique or a variation of a competitors theme. Specifically I'm interested in ease of servo installation, surface tightness after installation, long term wear issues, and drive system component quality. Discussion of specific models and their supplied drive systems is especially appreciated. I'm looking at many of the top F3B models and this is a very important consideration for me.

Thanks
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Feb 19, 2016, 10:51 AM
Registered User
Dyno Don's Avatar
Tappet,

I'm not a Top F3b guys but I have had several F3b models with each drive systems.
The RDS works well but gets a bit sloppy as time goes on.
The pockets can be addressed to tighten things up .

My "Radical Jazz" from Martin Webbershock has the LDS system and has been super tight and very accurate. Installation is easy but requires some adjustments and fittings before you do your final assembly..
My experience with the RDS system has been that they required a bit more adjusting to get throws I needed on my flap travel. Then you need to duplicate those position on the other wing to keep your travel in-sink with each other.

My vote is the LDS system if you have the choice..

Best Regards

Dyno Don

QUOTE=Tappet;34045782]I'm looking for opinions on the various rotary and linear surface drive systems used on current top end F3B gliders. It seems many builders use their own technique or a variation of a competitors theme. Specifically I'm interested in ease of servo installation, surface tightness after installation, long term wear issues, and drive system component quality. Discussion of specific models and their supplied drive systems is especially appreciated. I'm looking at many of the top F3B models and this is a very important consideration for me.

Thanks[/QUOTE]
Feb 19, 2016, 11:06 AM
F3B
satinet's Avatar
Lds>rds
Feb 19, 2016, 12:53 PM
Registered User
The best result might be both. RDS for ailerons and LDS for flaps. But definitely LDS before RDS if they fit. Less wear problems than RDS and more flap travel. RDS might be thinner for ailerons. I hate the horns that stick out on most f3j models.

The baudis models with RDS are all built well and durable. My LDS experience is with Freestylers and that linkage works well. The only challenge is putting the pins in if you have molded wipers. It's easy to chip the wiper if you slip with the pliers. All my models are JR398HV (ds189hv)
Feb 19, 2016, 01:14 PM
Registered User
Thread OP
Thanks for the input so far. More model specific opinions please. Ceres? Fosa? Ascot? Extacy?

Thanks.
Feb 19, 2016, 02:10 PM
F3B
satinet's Avatar
Only the fosa is current of those.

I don't see the point of lds or rds in f3j and other slow speed disciplines tbh. Not sure the drag refuction is worth it. F3b or f3f debatable. They don't use it in f5b.

Rds can never work truly properly. The hinge line isn't inline with the shaft. The wing skin will go soft. Yeah you can get sliding servo rds i guess.

Top f3b planes:

Fs3
Fs4
Fosa lift
Fosa
Jedi (pitbull?)
Avatar
Radical jazz
Pike precision
Etc

From what I'm see the pike and the radical jazz seem the planes du jour. Clearly the fs3 is the most popular f3b airframe of recent times.

A lot of planes have the lds installed. On my avatars i only had to screw the servos in. Freestyler pike jazz you can get the system installed. Baudis will do planes virtually ready to fly ( ditto pikes)
Feb 19, 2016, 02:31 PM
Registered User
Thread OP
Thanks Satinet. Do you know any particulars about the system in the Fosa Lift? Preinstalled? Good system?
Feb 19, 2016, 02:37 PM
F3B
satinet's Avatar
Baudis stuff has had rds supplied for quite a while (since the era of the Ceres?). Not installed but supplied unless you pay to have the gear put it.

I know they started doing lds for the flaps but i don't know if it's installed or if they do it for ailerons now. Don't know anything about it sorry

Rds on the baudis stuff is good as rds goes.

Personally i would probably get a pike precision at the moment.
Feb 19, 2016, 06:04 PM
Portsmouth & Malta
Hi, I can confirm that Baudis are actually installing LDS for ailerons, and give you a choice of what servos you're planning on using. i.e. They will make the frame and bearing to suit the servo, even the 6110.

Oh, not preinstalled in the Lift, but everything supplied.
Feb 20, 2016, 05:17 AM
Heavy's good, heavy's reliable
BDK74's Avatar
I think they all have their strengths and weaknesses depending on what you're looking for.

RDS is a very simple system and easy to install. Better for ailerons if you don't mind a relatively slow response and a bit of slop over time. For flaps it's not the best. Installation becomes much more critical, travel is limited to about 50-60*, and they can be very hard on certain servos.

With some of the new HV wing servos the LDS is definitely superior to RDS. It puts a pretty big demand on servos but there's lots of travel and faster movement. The new Samba LDS looks to be pretty durable and serviceable.

I guess it comes down to what you're looking for from what plane.

I've changed a few planes from RDS to conventional linkages and it completely changed the plane for the better for me. I'm pretty biased toward conventional linkages for my style of flying. There's lots of good hardware available to make some killer linkages that can be adjusted and repaired.
Feb 23, 2016, 03:16 AM
isoaritfirst
isoaritfirst's Avatar
I've had Baudis RDS, FS3 linkages, FS4 LDS, Shinto LDS and a few more,

Like Tom said above ask why you want LDS or RDS.

Plus side of both LDS and RDS
clean aerofoils and a nice looking wing.
less drag.

RDS only gives smooth rotary action with potential for good "gearing" such that all of the servo travel is used.
No expo induced.

Factory install is much easier with LDS, with systems now (Shinto) that have servo frames and linkages installed so that only the servo has to be plugged in.
Good installation - much better than a average builder is likely to achieve with rods and clevises.


Negatives of RDS and LDS are they are
power hungry,
damaging to the hinge line.
RDS wears and becomes sloppy, especially if you have rods that are bent to give large flap movements.
LDS often has very poor gearing, sometimes even negative, giving poor servo resolution, very fast less controllable surfaces.
Remedied by using expensive servos.

RDS is harder to look after and any landing with flaps down may result in a broken pocket.
LDS is harder on servo and any landing with flaps down is likely to strip servo gears. (due to poor "gearing")

Rods - clevises.
Easy to maintain, gearing can be adjusted to suit servo allowing full resolution and strong slop free installation, with some degree of expo induced.
Less expensive and less power hungry servos can be used.
Easy to maintain and less prone to damage of surfaces or servos if designed with correct "gearing"

Not so pretty to look at.
Slight increase in drag - speed dependent on if this is valuable or not.



Personally I go with LDS - on my F3f models I like the look and the simple factory install. Although the "gearing" does nark me..
On anything else probably best to stay with rods and clevises.
Last edited by isoaritfirst; Feb 23, 2016 at 03:23 AM.
Feb 24, 2016, 07:54 AM
Registered User
Thread OP
Great info in your reply Isoar!! Thanks for taking the time. Bottom line...,I don't NEED or WANT either RDS or LDS, it's just that I'm looking at high end F3B models for sport flying (!!) and they all come with one of the two type drive systems. Conventional linkages would be fine but I don't have the skills to mod a bird to accept them.
If I'm considering spending $2K on a new bird I want one with the best drive system, be it RDS or LDS, hence the questions.
Feb 24, 2016, 09:18 AM
Registered User
Both RDS and LDS are fine with all the current models. If you are used to conventional linkage and TD type models, then get LDS on the flaps. RDS is OK, but you will have to be more careful with speed on landings compared to what you are used to.

The reality is neither one is any harder to install than conventional linkages. In fact, I consider LDS just a well made conventional linkage. Even on regular linkages, I like an outboard bearing on the flap servo.

My newest models are LDS. So that is my vote. If the wing was really thin at the singletons, I'd take RDS if that was needed to make everything fit in the wing. I hate anything sticking out of the wing. Even with conventional I try to eliminate any bubble on the bottom of the wing.

At the Gator F3b in March, my guess is LDS will be the highest number followed by RDS.
Feb 24, 2016, 10:50 AM
isoaritfirst
isoaritfirst's Avatar
All very true,
LDS is just the same as a poor rod set up.
LDS wins over a poor rod set up because it will be engineered much better with better bearing surfaces.
But if you compare LDS to a wing with bubble and a decent length of horn/arm then the rod wins for the reasons a stated earlier. Much less stress in the setup. But that comes with the price of a bubbl in the wing.

If you want that clean wing then LDS is the way to go.

I do like the clean wing and go LDS -
I also like the Shinto's solution of being built with the servo frames and rods in place.
But I did build one of the very first FS4 with LDS and it was simple enough, once I figured out a way to get the pins into the surface to arm connection. Its documented in the FS4 thread a few years ago.
I also wrote a small article that is around on the net titled the Easy flap install. This was written before LDS but actually uses the same principles of building all the rods as identical pieces and then connecting to the servos before allowing the servos to position themselves within the pocket.. Making for a balanced install.
Feb 24, 2016, 01:41 PM
F3B
satinet's Avatar
Freestyler 3 with the conventional linkage is a good choice.

Tbh I'm not aware of any f3b where you can't not have rds or lds. Just order without and put a conventional linkage in if you want.


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