build Forza-E

[EarlyBird]

Thanks for all the suggestions guys and after a lot of thought I went with the clevis solution. 

 

And here they are waiting to be glued in. 

 

Next the ailerons.

 

Steve

[Konrad]

Ok, Don't see that the keeper side of the clevis has been ground to clear the servo output shaft.

 

This is more of an issue with the flaps. I'm assuming that your model has factory installed fiberglass control horns. As the flaps go past 60° the clevis tends to bind on the wiper. Please make sure that the wipers are relieved to allow the clevis arms to pass. 

 

I've found that with the staked pin of the style of clevis you are using, that the pin tends to broach the hole in the fiberglass control horn (see red lines). This is one place where I do see that the CA hole repair is effective as there is enough fiber to allow a good bond with the thin layer of CA. I generally like the seperate clevis pin clevis designs for this aplication, such as those made by MPJet.

 

 

P.S.

With the flaps you will generally want the control horn pivot hole placed at 80° to 75° (not 90° shown) to allow leverage in the full down position. As the flaps don't move up as much as ailerons this isn't an issue with modern radio programs.

 

Edited April 7 by Konrad

[Konrad]

Before you get much further along with the build, have you checked that the wipers and control horns allow the surface to move enough to at least meet the factory callouts? 

 

Take a look at this thread for ways to make adjustments if needed.

https://forums.modelflying.co.uk/index.php?/topic/61778-aeroic-alpenbrise-157-konrad’s-gag-4-meter-f3f-racer/#comments

 

[James Hammond - Aeroic]

11 hours ago, EarlyBird said:

Thanks for all the suggestions guys and after a lot of thought I went with the clevis solution. 

 

And here they are waiting to be glued in. 

 

Next the ailerons.

 

Steve

Steve - if you are set on glue, some advice: Back in the day we used to use silicon rubber fishtank caulk to do the job. It actually sets frmly but will provide a tiny bit of 'give' in a "firm arrival"😝 and also the servo can be 'manoeuvred' for quite some time before the caulk sets.

 

If you want to use a harder glue, then 5-minute epoxy is horrible stuff but it works. With the 5-minutes stuff It's a good idea to wrap a couple of layers of masking tape around the servo first to allow it to be firmly in place but possible to remove for replacement or repair etc.

 

Cheers,

 

Doc. 

[Konrad]

I had assumed you were using the supplied servo trays. These should be glued in with high quality 60 min epoxy. While I agree wholeheartedly with the advice against using 5 min. I’ve recently soften my stance a bit in that JB Weld Quick Set epoxy has worked well for me. Be warned that 5 minute epoxy’s don’t give you much working time!

 

If using a silicone adhesive do think about imbedding a cut wire (dental floss works well) to help facilitate the removal of of the damaged servo. 
 

If gluing in the servo directly I like to protect the servo against any adhesive with heat shrink film rather than tape. Again this helps facilitate the removal of the damaged servo. If using epoxy to glue the servo the remnants after pealing the film will allow for quick indexing of the replacement servo. 
 

 

Edited April 8 by Konrad

[EarlyBird]

Here are both sides of the ailerons waiting for glue. 

 

As you can see at the bottom the use of the clevis has caused me to budge up the installation. I think there has to be a better way. 

 

Steve

[Dickw]

That doesn't look too bad to me, and you could always make up a small shroud for it.

I have attached an image from one of my F5B gliders regularly flown at over 150 mph, and the pushrod exit looks similar to yours. It is a bit smaller as there is no clevis and the pushrod is just held in the horn by the wing skin, but that is for a competition glider pushing the limits on a weight and drag compromise.

 

Dick

[Konrad]

To my eye it looks ok.  It looks to me that you used a blade to make the needed clearance.  Generally I use jewlers files. It looks like you could use these files to clean things up. Don't forget to radius the new corners on the wipers. This is done to try to minimize wiper hang up (bind) on the top wing skin.

 

And when glueing in the trays, have the servo are 90° to the servo body with the servo centerd. And tape the surface to be in mid throw. ( this might be 10° up on the ailerons and 35° down on the flaps.) adjust the push rod so that the servo is positioned to clear the wing skin (in profile) and that the servo arm doesn't bind against the spar web. This will then place the servo tray properly in the servo window. With adjustable push rods this isn't critical. Again look at the servo installation with an eye to proper mechanics.

 

P.S.

That red aileron servo arm looks like a low profile arm. Does it allow the clevis arm and pin to clear the servo body?

Edited April 10 by Konrad

[Konrad]

Ops, I see I have a major typo. Servo centers are generally spec's at 1.5ms not 1.5µs as posted earlier.

[EarlyBird]

On 10/04/2025 at 12:42, Dickw said:

 

Excellent idea I will see you on the same lines but was going to use a small collet to keep it in place. 

 

Steve

[Konrad]

On 10/04/2025 at 04:42, Dickw said:

That doesn't look too bad to me, and you could always make up a small shroud for it.

I have attached an image from one of my F5B gliders regularly flown at over 150 mph, and the pushrod exit looks similar to yours. It is a bit smaller as there is no clevis and the pushrod is just held in the horn by the wing skin, but that is for a competition glider pushing the limits on a weight and drag compromise.

 

Dick

Is there another retention feature as the flaps near 90° and the push rod clears the upper skin?

[Dickw]

14 hours ago, Konrad said:

Is there another retention feature as the flaps near 90° and the push rod clears the upper skin?

The servo horn rotates up as the flap horn rotates down, so there is not actually that much variation in pushrod height. However, a similar cutout in the wiper would take over if the pushrod ever cleared the upper skin.

I tried to upload a photo of down flap at about 80 degrees, but the website server keeps giving me an error code  this morning - perhaps I will try again later.

 

Dick

[Konrad]

Ok, got it. How was the pushrod installed? Was the control horn loose allowing for the needed lateral motion of the pushrod into the control horn? And then the horn with the push rod installed was glued to the control surface?

[Dickw]

1 hour ago, Konrad said:

Ok, got it. How was the pushrod installed? Was the control horn loose allowing for the needed lateral motion of the pushrod into the control horn? And then the horn with the push rod installed was glued to the control surface?

The model was supplied with servos and pushrod ready installed, but my understanding of the process is as follows:-

 

1/Servos glued in and pushrod installed before moulded wing upper and lower surfaces glued together in the moulds (there is no access to the servo after construction apart from surgery).

 

2/Once wing is taken out of the moulds the pushrod outlet hole is cut and the pre bent pushrod end extracted.

 

3/Servo powered up so it can be set at a pre-determined relevant point.

 

4/The surface horn is then placed on the pushrod and glued into the surface at a relevant pre-determined surface position.

 

Perhaps an unusual form of construction, but it has been common to the small/fast 2m F5B gliders for several decades where weight and drag are a never ending battle. See Avionik, Surprise, Speedfire/Backfire, and some home-builts.

 

I often glue/install the surface horn after I have the servo and Tx set up even on much simpler models that have adjustable pushrods.

 

Dick

[James Hammond - Aeroic]

Its probably a bit late for these builds, but the latest issue of Aufwind has a great review of the E-Forza by Markus Thewes - very detailed indeed, and in the next issue Markus will review the slope version. 

 

Of course there is also my own Gliding and Design column inside. 😇 

 

Cheers,

 

Doc.  

Edited April 15 by James Hammond - Aeroic

[Konrad]

10 hours ago, James Hammond - Aeroic said:

Its probably a bit late for these builds, but the latest issue of Aufwind has a great review of the E-Forza by Markus Thewes - very detailed indeed, and in the next issue Markus will review the slope version. 

...

 

Cheers,

 

Doc.  

 

This is great news. Will this detail migrate into your manual? Or are the contents of the magizen copyright protected?

 

I wonder what RCM&E thinks about the active promotion of a competing product, in the same language, on the RCM&E Forum?

[James Hammond - Aeroic]

18 hours ago, James Hammond - Aeroic said:

Its probably a bit late for these builds, but the latest issue of Aufwind has a great review of the E-Forza by Markus Thewes - very detailed indeed, and in the next issue Markus will review the slope version. 

 

Of course there is also my own Gliding and Design column inside. 😇 

 

Cheers,

 

Doc.  

Dear admins - if I have violated any policy here I aplogise. This post was simply to let anybody intertested know that there is a lot of information available on building the Forza - that and only that. In no way was it intended to be an advertisement. Thanks for your indulgence on this. I will try to be more careful next time!🤔

 

Meanwhile there are a lot of Forza builds going on at this moment. 4 models are finished this month, and at least 9 counting USA and Europe are in the build phase, and as has been pointed out - although better than no manual at all, my instructions are really meant for very experienced builders, used to reading between the lines.

😳I tend to forget that not everyone is so experienced, and this is why I thought it might be good to make a new source of very comprehensive information available.

 

Again my apologies for any infingement.

 

Cheers,

 

Doc.

 

  

[EarlyBird]

Thanks Doc.

This experienced builder of seven years knows exactly what you mean. 

I have glued the four formers and servos into the wing. Next is the elevator former at the back. 

here it's ready for glue, but a test fit proved me wrong. The only way I could get the servo through the small access was to use the masking tape and glue method.

 

More to come. 

 

Steve

[Konrad]

Have you looked into using separate mounting blocks?  This worked well on the smaller servo window Schwing Corsa 108, (See the yellow set up towards the end of the photo trail)..

 

[Konrad]

Please rethink placing bends in all thread rod, particularly 90 degree bends. There is a surprisingly high shock load on the tail in some landings. 
 

Also with that short a push rod the angle of the secondary motion will tend to wear out the threads in the arm. Please look into using a two spherical joints with that very short push rod and with servo axis being 90 degrees to the hinge line. 

[Konrad]

Sorry on a second look, using a monitor, I see that there are no threads in the bend radius. I see no threads in the servo arm. I do see a “blob” at the end of the 90° bend. Is this epoxy, being used as a retention feature? Will this feature clear the body of the servo at one end of the arm’s motion?