Servo and link fitment using IDS

[Darren_O]

I've bought some frames and integrated drive system from http://servorahmen.de/index.php?id=35&tx_ttproducts_pi1[backPID]=112&tx_ttproducts_pi1[product]=145&cHash=fe8bc4d2df here. No instructions

I've searched on the net and the wedge fits into the control surface itself. Does this just go in flat? I can't get my head round which way up it goes and if it needs off setting in order to move aileron up and down as a brass peg would. Or does the design of the wedge allow this already...


 

[Andy_B]

If you look at the peg its already offset

[Darren_O]

Thanks for the speedy reply Andy.
It is very slightly, I take it that's enough? Which way up does it go?

 

[Brett82]

Hi Darren

When I was thinking of upgrading my Skorpion to IDS I tried to read up on it as much as possible and looked for as many videos as I could find. I hope someone will correct me if I am wrong but what I understand is the side that glues to the top skin is the side that has the hinge. You would need to cut some of the wiper away and the hinge part sits as close to where the wiper would have been as possible.

This means as the flap/aileron is bottom hinged it gives the greatest distance possible between the control surface hinge and the hinge on the IDS system. 

I will try draw it in ms paint and upload it but I'm at work so need to be discreet. I will also see if I can find some of the links I looked at. haha.

Brett

[Brett82]

Please don't shoot me if its not to scale or drawn correctly, I did this as quickly as I could without my boss seeing. This would be a side view, hope it makes sense. 

Brett

[Brett82]

Have a look at the image on the below link, it shows a nice side view of setting the servo arm so you get maximum flap down. May not need to be as extreme but it gives a really good idea of how it works. 

http://f3j.in.ua/drive-systems-ids-type-mks-ds-6100-for-flaps-of-supra-2pcs-2030.html

Below is an image of the top of a Shinto wing that I found. It shows how the wiper has been cut awau to fit the IDS system andf how the hinged part of the system sits close to the top skin of the aileron/flap. 

Brett

[isoaritfirst]

If you are having trouble already just wait until you start to fit them. 

Make sure that you work as accurately as you can.

Use the shortest servo fitting you can and the longest surface fitting that you can, do not try to conceal everything under the wipers. Make them so they scrape along the inside of the wing skin, and thin the skin a little if need be. The longer you can keep the surface arm the better the resultant movement will be.

 

Make up the aileron servo, servo arm , push rod and surface arm. 

Ensure your servo is centred and the arm is running perpendicular to the top skin. Position it all in the wing and cut the push rod to length. Now make another set exactly the same for the other aileron.

Cut the wiper to suit, then glue the complete assembly all in place, ensure the servo is still centred correctly then tape the surface level and position to allow the epoxy to set in the correct position.  Check before it dries that the surface arms pivot point is nicely positioned perpendicular to the hinge line, and as close to the top skin as possibly.

If you keep the surface held in position the servo should position itself, just ensure it is sitting nice and square to the hinge line and not putting any twist into the pushrod.

The flaps are similar but the servo position needs altering to allow the surface level to corespond with the servo at around 7/8 of its rotation. The surface horn position will appear to be further forward in relation to the wiper.

 

[Darren_O]

The wing and aileron already have pre moulded bumps for a peg and control arm and the wiper is already removed....the aileron is bottom hinged. 

Obviously it has to go in deeper, but which pic is correct way up? One brings it further from hinge giving it more authority but doesn't look right.

[satinet]

Why?

You've got the servo exit bumps already, so you won't be saving any drag by using LDS.  I would just install the servo horn with the supplied brass horn and use one of the longer servo horns. You will have a better linkage.  There will be less stress on the servo, lower power consumption, easier install, and easier to repair.

The big problem with this LDS is that I can't see a way to install the horns equal either side for the flaps. You will likely end up with uneven movement.

I really don't see the point of installing under the wing skin LDS in a model that has large exit fairings. You could install a close DS strength linkage in that model within the moulded fairings, with non of the downsides.  I definitely wouldn't install LDS in an aerobatics model and even in high end contest models the benefit is small. 

[Brett82]

Hi Darren 

The top pic is correct. As you push it in further the rounded top part should sit as close to the top aileron wing skin as possible between the two cut wiper. 

Brett 

[isoaritfirst]

LDS isn't anything new its just servos and push rods.

 

It allows for very short servo arms and surface arms making a clean installation that will sit within the wing.

It has no other benefits.

To achieve the clean install it requires good quality engineering and strong pivot points. 

The nature of the design puts extra pressure on hinge lines, and extra pressure in the pivot points.

LDS systems rely on using high power/high quality servos as the mechanical advantage is often very poor. 1 :1 is not good and  some, if installed badly are worse than that, leading to very poor servo resolution, giving poor surface control and high power usage. They then only work due to the very high quality of the servos. But will always suffer with some degree of poor centering.

That said, if its done well and you have expensive servos it can be very nice. Most of my models are now LDS.

Have a look at this piece I wrote many years ago covering a pushrod installation on my FS3. it features fixed /soldered pushrods and clevises - the install method is the same that needs to be adopted to install LDS.  

On the FS3 install the servo arms and the surface arms are longer than an integral LDS, this reduces hinge stresses, takes stresses off the clevis pivot points and allows a design that has good mechanical advantage.  Reducing the stresses reduces pivot point and servo gear wear. That model is now around 10 years old and still has tight well controlled surfaces despite running on Futaba 3150's that Tom will tell you are a sloppy servo.

You need to ask yourself , why do you want LDS, 

My answer on my F3f models is to create a nice clean wing. But to add further insight I recently removed the initial install on my Shinto and replaced it with a different LDS system just to gain a mm in extra length on the flap horns and fit a slightly smaller servo arm. I now have flaps that centre well and control well even through small movements, those small changes can make a big difference on LDS systems, and highlight just how important it is to install it very accurately, not only to get good resolution but also to ensure flap movements are identical to each other etc.. 

http://www.rcmf.co.uk/4um/slope-soaring/easy-flap-install/

 

 

 

 

[satinet]

Mike is exactly right. Lds Is only to get the linkage under the wing skin.

Otherwise it's basically all disadvantages including worse horn ratios and it becomes a ball ache to repair the hinge etc.

I don't see any point in lds in this model. 

[isoaritfirst]

Just to complicate things further you need to understand this picture.

The black line I have drawn in indicates the pushrod run and the resultant axis of the surface horn.

As its drawn the black line would result in a surface that had unecessary slop around the centre and also gave  a movement that would give more up than down throw.

The Yellow line gives a 90 degree angle to the push rod and therefore has minimum surface slop and gives equal movement around its centre.

The Blue line shows an off centre arrangement for a flap, to give loads of down and little up. It will also give sloppy control around the centre but the compromise is necessary here

All of course will also be effected by the servo horn position. For the yellow (aileron line) the servo arm should also be perpendicular to the pushrod.

For the Blue flap line it should be fpositioned to allow it to be able to move the flap to its max deflection when the arm is pointing down along the line of the pushrod.

 

You need to understand these principles well, and use then when positioning the surface horns. Also notice that the changes on the drawing have effectively lengthened the resultant surface arm length. which is a good thing!

[Andy_B]

I have to agree with Mike and Tom ...use the brass horns   Ive used them on this setup before and there great

[Darren_O]

"why do you want LDS"

I thought it was the very best option and latest tech. Never took into account I already had exit bumps on AIL and Wing for pushrods, I was more focused on a slop free install and figured this was the best option.

If the only advantage of the wedge is a stealth install then I may as well use the supplied peg and the old pushrod. Really appreciate everyone's input, I've got so much help here. Be lost without it.

[satinet]

The servorahmen frame is a good option for low slop. There is just no point going under the wing skin.