Selleri

Mike that's a different type, notice the stand off flange on the white hinges!

BaldEagel

Yes I did see that, also the hinge point has only one flange, not multiple as the grey ones.

Mike

DominicM

These the same? Lots cheaper.

http://www.giantcod.co.uk/pivot-roun...-p-402871.html

http://www.hobbyking.com/hobbyking/s...idProduct=8281

Selleri

Check them carefully if you use them Dom, they are sometimes made of a more brittle plastic!

BaldEagel

You just beat me to that. have found in the past that some inferior offerings are very brittle and snap in the hands if you flex them, the Graupner offerings seem to be much better quality and have some give, you will have to bend one a long way before the fixing pin gives way, even then the multiple flange hinge points have a lot more tolerance prior to the hinge failing, not sure about the single flange white one's.

Mike

Selleri

Great minds ehhh!

Xairflyer

My Feedback: (1)

Dont use the giantcod/hobbyking robart style hinges they break at the hinge point, I know !
lots of chineese plastic is poor, anything I buy now I always break one or two to test.

BaldEagel

Don't try your stress test with any of those so called Phenolic horns you will scare yourself, I know I did when I first tested them, just leaned on them a bit and snap they where in half, dosn't seem to matter who they are from even the CARF ones come with a warning not to use ball links as the side load will snap them.

Mike

Xairflyer

My Feedback: (1)

We call the Chinese materials Cheeseim

marc s

Agree with the quality thing, just not worth saving the few quid on items like horns etc, these seem very tough.

marcs.

marc s

OK here is the latest from the few hours snatched between festive activities.......... Oh and a Happy New Year to you all.

The hinges were in and the holes matched up on the wing, easy job with a Robart hinge centre tool - the wing spar is glass faced airex so easy to work with, its also thick in the locations where the hinge points fix so I suspect the areas are thickened up during manufacture which is nice.

On checking throws the aileron was very happy, I am awaiting information on throws but get a good 1.5" each way on these so should be plenty. The flap was not as happy, I wanted to get around 60 degrees at full flap, the max on first fix was around 40 degrees. After a few checks I noticed the wing trailing edge had not been finished straight along the whole trailing edge, it bowed in towards the wing root area, this caused the flap to bind along this area. A straight edge and some sanding sorted this out easily, and the flap was happy to deflect 60 degrees.

Lined up the aileron and flap on the wing dry, deflected the surfaces to the desired point and marked the control surfaces to give me the max forward location of the horns leading edges.

As the arrangement for servo fitment is designed to be very simple, reminiscent of the Seb Art kits, the servos drop into pre-cut pockets in the wing skin, and fix to plates pre-fitted during the wing manufacture. These plates are sturdy and are carbon cloth covered ply.

The plates are pre-cut for a servo, JR8411's were the planed servo but found them to be slightly wider than the cut-outs, not really an issue as they are easily adjusted with a file but nonetheless it got me considering alternative servos. A friend suggested a 'economical' alternative, and following a little research I opted to go for these - GRAUPNER DES707 BB MG Digital's, these are rated at 133Ncm at 4.8V and 150Ncm at 6v, being German the quality is very good, price is very keen and they fit exactly in the pre-cut slots.

Linkages again due to the position of the servo mounting really require a ball link at both ends of the control rods, this prompted me to order some servo arms along with the servos from the same shop which incorporate a ball link between two moulded arms, this seems a safe and good way to drive ball links from the servo arm, rather than use a single arm and all the issues and stresses this creates with ball links. I opted for M3 rod connection.

Supplied with the kit are epoxy glass horns, these are a 'standard' sized unit which require trimming to suit the control surfaces, two horns are supplied for each control surface which again is the best option to contain the ball link set-up. After assembling the twin horn and ball link unit I was able to cut slots in the aileron and flap to suit the spacing. Whenever possible I use a small Proxxon milling machine to cut slots, it makes a very neat slot, you can control the depth (18mm from memory) to give a good area to epoxy in the horns.

The aileron had hard points where I slotted the surface, the flap did not, so I made sure the flap control horns seated on the top skin, scuffed and added notches to the horns before fitting with Aeropoxy. I may cut an opening in the flap side once dry and feed in some aeropoxy, but this depends on how secure they feel once set.

After fitting the control horns in and tidying up the glue joints I applied aeropoxy to the aileron and flap pins and slotted them into the wing - aligned the trailing edges, taped and left them to dry in a warm room.

One nice touch is the wings have a tube running from the aileron pocket through to the wheel well area so you can route the servo cable easily back to and out through the wing root, I used the bath plug chain method to route to the servo pocket, attached the servo extension to it and pulled back through. Never had a wing where the bath chain has failed to get to where you want it - not sure where I first saw this method but its a real handy 'tool'.

I'll sort the second wing out now and then start on the stabs.....

marcs

marc s

few more....

marc s

Carried forward £26.97

Graupner DES 707 BB MG x 7 @ £24.00 each - £168.00
Assorted servo arms and ball links - £31.00

Running total £225.97

marcs

BaldEagel

The added bling value by using carbon for the horns is worth it I think: http://www.rcuniverse.com/forum/m_7203928/tm.htm

Mike

marc s

Come on, for once in my building life I am trying to be conservative and cost conscious - usually chuck all the hardware in the bin but this time I'm re-cycling, besides going to paint them (the horns) the red colour from the control surface so if I'd bling it it would be lost under Humbrol fire red

marcs

BaldEagel

Mike

BaldEagel

Did the servo's come with the cap head screws?

Mike

marc s

Um yes, well maybe no - lost my phillips screwdriver so had to resort to those cheapo screws you see

marcs

siclick33

Marc,

Have you used those servos before? They look like a good spec for the price.

Are the arms shown in the photo with the packet the ones that you are using on the servos? It says Futaba on your packet but I thought Graupner servos had a JR spline?

Dave Wilshere

Mike nope, been around years and years. First Harpoon included a few for AB hinging, but were white and like that long before. That and the flat No 53 hinge have been on most of my Jets for 10 years +

Dw

marc s

Not used them before and yes look to be a very good spec for the money.

I know a few others who have sent me PM's on these servos that they have a good reputation, it also seems they are a Savox based servo which Graupner 're-work' hence the Futaba splines.

The arms that come with the servos are the normal range of strong white items, the ones I have used are non standard and picked to handle the offset nature of the linkage requirements.

Hinged the tail surfaces the other day, will post some pics later tonight when a few other jobs are sorted.....

marcs

steve2972

My Feedback: (2)

Hi Marc,
What size servo arms did you order,small or medium?

ta

marc s

Steve,

Used the 17mm on the two ailerons and 25mm's on the two flaps so far, not sure on the elevators and rudder yet as its a work in progress, should be able to advise on elevators later today.

Cheers
marcs

bigplumbs

These are also a very good standard size servo. You get some very nice fixings with them also

http://www.kingslynnmodelshop.co.uk/...duct_info.html

Bod

marc s

Little more done to the control surfaces on the stabs.

Cut and used the same hinges as per the ailerons and flaps, when it came to fitting the elevators to the stabs due to the angle of the elevator cut-out it was impossible to get the hinge pins into the holes made in the stab, eventually I needed to nip off two sections from each pin and this gave enough margin to flex the pins into the holes and slide the elevators into place.

Aeropoxied in the normal way.

The Graupner servos fit exactly into the cut-outs already pre-made in the stabs root face, the system will require an opening to be made in the fuselage to allow the servo body which protrudes from the stab to sit inside. I measured up where the servo arm would exit the stab and cut a generous slot so the arms I was using which are Y ended could be fitted and secured on the servo output shaft before fitting to the stab, looking at the options it would be almost impossible to fit the servo and then attach the arm.

The servo is secured with 4 servo screws which are held secure by the ply root former fitted under the fiberglass shell.

Deciding on the angle to mount the horns (double for each surface) was not a simple process, due to the mounting method for the servo a straight linkage would actually miss the elevator, so the linkage would need to be angled, not a problem as the linkage has ball links at each end but I decided to 'create' some new horns to allow the linkage fixture point to be closer to the hinge line - its not spot on but a little nearer than possibly the stock horns would deliver. I suspect the supplied horns would be fine but after an hour on my little mill it seemed silly to waste the results?

Slots cut, the horns were scuffed, painted above the surface join and aeropoxied in place - they will get a week to dry as I'm off to bash the white fluffy stuff in the mountains for a week

marcs