The place for technical discussions about GA and flying.
Forum rules: Technical discussions about GA only, please.
By thegasguy
#1601434
Has anyone changed the simple lever type trimmer in a Jodel for anything more sophisticated?
The position of the original fitting is inconvenient to say the least.
As I sit flying it is on the cockpit sidewall just behind my left bicep. To use it I fly with left hand on the stick and reach accross with my right hand in 90% of a "folding my arms" motion.
It's utterly inaccessible to my left hand, about 2 feet too far back.
It's also fiercely sensitive, breath on it and up,or down, you go.
Having said that it's been like it for 61 years, so it can't be that bad !
I'm just pondering if a 'winder handle' mechanism like in a supercub could be fitted further forward, with gearing down built in.
I'm aware this is heresy, - just asking cos it's raining and I'm bored.
User avatar
By Kittyhawk
#1601705
You might get more information on the Jodel Club forum on Yahoo.
I would think not a simple mod, as currently the lever also acts as the trim position indicator and you would need to incorporate that requirement. Can you not just move the lever mounting point forward a bit? It is just a geared drive to a Bowden cable.
User avatar
By Flyin'Dutch'
#1601715
Indeed.

Assuming on Permit talk to your inspector about moving the lever forward and putting a longer bowden cable in.

The Jodels I have flown all had the lever in the location where you find the throttle in Cubs.
By thegasguy
#1601734
Good point about trim point indication, the only SuperCub's I ever flew had a simple 'pointer' built into the mechanism. That's the sort of thing I was thinking about.
Naturally I've thought about moving the original - every time I fly actually!- but it would involve replacing the Bowden cable with a longer one and this is quite a job as access to the clips in the rear of the fuselage is almost non-existent.

My thinking was,I f I am going to go to this much trouble then a 'better' mechanism at my end would be nice.
There is no gearing, it's just a little lever reminiscent of the 'advance and retard' on a vintage motorcycle.
It has a nice friction control knurled wheel built in.

I'm fairly sure it's original and very nicely made, but very awkwardly placed.
I've had to modify all sorts to get my regular sized English legs in already, all I can say is, Frenchmen in the 1950's were a very funny shape!
But they did make lovely aeroplanes.
User avatar
By rf3flyer
#1601752
From your description I have the same mechanism in my aeroplane and I have seen the same thing in a Jodel and I very much doubt that a 'longer Bowden cable' is a realistically viable option. If it's the lever and cable thing that I think it is then it would require the incorporation of the rack at the lever end and the threaded terminal at the tab end. If you had the parts I guess it could be swaged together but that's all added complication and expense.

I agree about the difficulty of installing a new cable down the rear fuselage although if you have a small friend/syndicate member he might just be able to worm his way down a Jodel fuselage, but I could never see how it could be done on mine without partial de-skinning. However, IMO sourcing a longer cable with the appropriate terminations is the snag.
By Crash one
#1601765
Not being familiar with Jodels but could the entire lever mechanism be moved to the centre between the seats, aka Piel Emeraude? Prob require a cable re-route :(
By thegasguy
#1601785
The lever at my end doesn't incorporate any rack, it just captures the piano wire inner by it passing through a hole in a 'nut' that is some way up the lever and then being pinched by the screw.
This sounds awful, it's actually a bit better than that; the screw 'pulls' the nut part and thereby pinches the wire over a reasonable surface area.
It's made for the job and works well. I've replaced the inner piano wire and not had the slightest problem, apart from the position and the sensitivity.
At the elevator end the inner just goes through a pivoting nipple, like on old bicycle brake cables.
This is standard Jodel from1957.
I'd love the trimmer to be between the seats, but that's not possible as it's just the main spar we sit on and P1 and P2 legs are jammed tight together.
Extending the Bowden cable would be very easy, apart from clipping the outer at the back end.
It's getting a geared 'winder' on my end that I'm keen on, if anyone has done it.
I'm going to the Jodel fly-in at Popham next week if anyone has one I can look at.
No big deal, it would just be nice.
By thegasguy
#1602012
PaulSS;
Thanks for the link, if I fitted one of those I'd be drummed out of the Jodel union !
Looks like really good kit, but over the top for a simple aircraft like mine.
Unless I see a good solution on an existing Jodel I think I'll just soldier on doing 'auld lang syne' impersonations every time I use the trimmer.
Thanks all.
User avatar
By Genghis the Engineer
#1602304
Flyin'Dutch' wrote:Indeed.

Assuming on Permit talk to your inspector about moving the lever forward and putting a longer bowden cable in.

The Jodels I have flown all had the lever in the location where you find the throttle in Cubs.

Changes of this nature are far outside an inspector's remit - it needs to go through LAA Engineering in Turweston.

Airworthiness standards on trimmers are fairly minimalist, but there are things that need to be considered - for example that a longer lever gives the pilot's hand greater mechanical advantage and that needs to be accounted for further down the system strength-wise.

G
By thegasguy
#1602364
Genghis; agreed - the last thing I want to do is an unauthorised alteration to something as flight critical as the trimmer.
I was looking for someone who had done the hard yards already and then basically steal their mod- applied -for idea.
Each jodel I look at has a slightly different setup, one local to me has the identical lever, mounted the other way up!
Another has a carb heat type knob on the panel as the trimmer, so variations do work.
Rest assured I won't be making any changes without proper oversight, it's just a wish- list item.
User avatar
By Charles Hunt
#1604206
Rans S7, KATI was designed with a manual trim lever on the stick. During testing tab flutter was detected and so the manual system was removed and an electric system installed. All accepted by LAA.

(From memory and quick scan of log books!)
User avatar
By Genghis the Engineer
#1604226
thegasguy wrote:Genghis; agreed - the last thing I want to do is an unauthorised alteration to something as flight critical as the trimmer.
I was looking for someone who had done the hard yards already and then basically steal their mod- applied -for idea.
Each jodel I look at has a slightly different setup, one local to me has the identical lever, mounted the other way up!
Another has a carb heat type knob on the panel as the trimmer, so variations do work.
Rest assured I won't be making any changes without proper oversight, it's just a wish- list item.


Shout if I can help - I know the BMAA and LAA mod processes pretty well, and used to fly a Condor which is somewhat similar.

G