Multiplex Lentus

[tic]

Yes, but again, not as much as I'd like. I'd rather have more down flap than up travel

 

[Konrad]

Are you using Hitec/Multiplex servos? I wonder what is the reasoning for the short arms on the flaps. With everything else being so well thought out, having such a performance hit like this is just to save from having to make a larger hood sounds ridiculous. At the original time of manufacture it wouldn’t have cost more to make a larger hood if this hoods were made specifically for the Lentus. But if these are common parts over the Multiplex line then it was one of those project manager things that just drives me nuts! Saving a few pennys at such a high cost in performance!

Time to dig out the flap servos and install the proper servo arm length!

 

[Wayne]

If you like we could make up some larger hoods for you.

 

[Konrad]

Thanks I might take you up on that. But I should learn to draw one, in one of the hobbyist level CAD programs, and print my own.

 

[Konrad]

I butcher my models so you don't have to. Here I had to move to an 18mm long servo arm to get anywhere near the requiered flap motion.

I may have to bias the arm a spline forward to gain some mechanical advantage for the servo at full flap. This would cost me some up aileron motion. This will be one of the things I'm testing for in my flight tests/trim flight.

 

[tic]

I'm using the HS65's which is spec for the glider. I'm satisfied with the flap movement and do have a heavy bias for down flap on the servo arms. Not crazy about these servos but everything fit, including the connector pockets and the glider is in it's 2nd summer with lots of flights and no servo problems. Maybe the 65's have more travel, I don't know. I don't have 90 degree flaps but they aren't needed anyway.

 

[Konrad]

With the molded hinge the most flap I can get is 58° down. From there with the 18mm arm I'm able to get 24° of up flap.

 

[tic]

I would sacrifice up travel for more down if you can get it. It's not like you're going to be rolling this thing for fun all the time

 

[Konrad]

With the hinge bound, all I can get is 58 degrees measured. Did you give the hinge more relief (gap) than stock?

It’s not an RES ship. So I will be doing a lot of yank and bank work with rolls thrown in. I usually do a lot of this to burn the batteries back to a storage voltage. Unlike the FMS Fox I don’t plan on needing to use the motor as a flight sustainer.

Would you please post a photo of your flap action from the perspective shown in post #65

TIA

P.S.
That white strip is not the hinge gap. It is bare EPO to attach the gap wipers.

 

[Wayne]

Egad! That is a long servo arm waiting to catch every weed on the landing. Reduce the control horn on the flap. Looks to be room to drill another set of holes.

 

[Konrad]

That’s a good idea prior to the installation of the horn. With a proper arm it will only be about 4mm taller than the OEM hood.

But yes it will NEED the protection of a hood!

 

[gp49]

That’s a good idea prior to the installation of the horn. With a proper horn it will only be about 4mm taller than the OEM hood.

But yes it will NEED the protection of a hood!

You probably could use red hot, small, metal pin to punch a hole(s) thru that horn and then ream out

 

[Konrad]

I like the idea of burning a hole. But I still don't see how I'd drive a reamer without tearing up the aileron. The body/shank of the reamer would only be a few mm above the surface of the aileron.

 

[gp49]

I guess you can do some 'controlled' burning then to size or try something like a pin vise I use from time to time:

https://www.mscdirect.com/product/details/76493006

 

[tic]

couple of quick shots,, max flaps

 

[Konrad]

Ok, that looks like what I have in the way of downward flap movement. Really not that much. You can get the flaps back into profile with the arms and rotation of the HS65 servo?

P.S.
Actually It looks like you might still have 10 to 15 degrees of motion left in the hinge line.

 

[Konrad]

I guess you can do some 'controlled' burning then to size or try something like a pin vise I use from time to time:

https://www.mscdirect.com/product/details/76493006

The diameter (radius) of the pin vise is much larger than the radial offset of the hole above the surface of the aileron. So I can’t use it to drive a drill or reamer to make a new set of properly sized and positioned holes in the installed arm.

 

[gp49]

The diameter (radius) of the pin vise is much larger than the radial offset of the hole above the surface of the aileron. So I can’t use it to drive a drill or reamer to make a new set of properly sized and positioned holes in the installed arm.

many ways to skin a cat. You can always braze a drill/reamer to a small diameter brass tube and use it with you fingers. All it takes is time and a six-pack of good IPA.. Or just remove the multiplex horn and drill it

 

[Konrad]

Yes making tooling to clear the flap is an option.

Removing the horn is likely to damage a lot of foam around the horn.

I’m curious if anybody has found any reports on the lack of flap motion with the stock set up. I can’t be the first that has noticed this problem.

 

[Konrad]

Damn, drilling a new set of holes closer to the horn base (hinge) will NOT work. There isn’t enough flexibility in the forked horn to allow the retention barrel pins to pass.

Or put another way the forks will break off before the barrel will snap in place.