Peterf's 1/4 scale Falcon Models Tiger Moth

[Manish Chandrayan]

Looks the part Peter. Where and how will the aileron push rods be attached to the pulleys?

[PeterF]

Posted by Manish Chandrayan on 25/04/2016 14:22:20:

Looks the part Peter. Where and how will the aileron push rods be attached to the pulleys?

Manish,

To more than answer your question and provide some more background to other readers not familiar with the Tiger Moth controls. The aluminium pulley takes the place of the toothed sprocket on the full size, the full size has a section of chain let into the closed loop wire running from the cockpit. On mine, the closed loop wire will be attached to the outboard side of the pulley by a bolt so that it can not slip. As it is attached on the outboard side, the pulley will still be able to rotate 90° in either direction as per full scale. Below the pulley sits the crank and on the end of the crank is the aileron push rod.

Full scale aileron gearbox showing sprocket, chain and crank.

A simple sketch of my set up.

Photo from above with annotations.

[Manish Chandrayan]

Ahh ok Peter, get that now. I was assuming that the wires from the fuse would be attached to the crank. Quite clear now

[will -0]

Anyone know if falcon are still going? My link to their old website doesn't work any more and before that everything was out of stock due to "relocation"

[alan alldritt]

Ditto the last post - I have tried unsuccessfully to contact Falcon Models using a number of different addresses with the same result.

[Tim Hurn]

Hi All, I have been following this thread with interest and have just purchased a full kit from Chris Stewart intending to build it over the next few years. Chris has told me he is retiring and mine will be the last full kit he will supply, He also said he would continue to provide parts and help to anyone with an existing project. He can be contacted on <[email protected]>

Peterf and Manish thanks for the post. Loads of ideas and discussion as given me confidence to tackle a more complex project than the Traplet kit I already have. I will be selling the Traplet kit on ebay soon and plan to start the falcon version next winter. Hopefully this thread will be available for while for reference because I need all the help I can get.

On the subject of aileron drive did anyone look at sliding servo setup to amplify the throw. The idea is to mount a thin servo on sliding rails then anchor one end of the servo arm via a short push rod to something solid like the wing spar and connect the opposite arm to the aileron drive. As the servo rotates is will be forced to slide therefor multiplying the movement of the non-anchored arm. I have not done the maths but it should double the servo throw and allow the differential aileron movement needed.

[Manish Chandrayan]

Alan and will-0 have sent you a private message with email ID that I have used to correspond with Chris from Falcon models

[alan alldritt]

Many thanks Manish for the heads up.

ATB

Alan

[PeterF]

Tim,

That sure is sad news in a way, it is an exquisite kit and good to build and creates a fabulous model. I wonder if he will be selling the business / plans / rights to the design so someone else can keep manufacturing it. I know he is very good on support, I needed a couple of small bits recently and he sorted them out. I have also found that the Swiss company who make the flying wires, Aeroscale had disappeared off the web but they are now back. Anyway, when you get onto the build just shout if you need any ideas / help etc.

Continuing with the aileron control I judged that if I was going to use the full scale method with close to 180° rotation on the disc (90° either side of neutral) then I would have way too much throw on the ailerons and hence I have cut my own longer horns. These are the length of the full scale ones divided by 4, so the geometry should work out. The gearboxes have been installed using hex head servo screws. I have made up my own push rods with a core 2mm steel rod threaded at each end inserted into a 4mm OD x 2mm ID carbon tube with 2mm ball links that have 4mm bodies to match the carbon tube. Two reasons for this, the first being getting a good strong push rod in both compression and tension, and secondly it looks a lot better and closer to scale. There was a lot of fiddling about to get the push rods just right, I had to clamp the ailerons in neutral, the gearboxes with the correct 45° forward offset and measure, cut the rods, then keep trimming them down until they fit.

Aileron gearbox installed from above

Aileron gearbox installed from above

Longer aileron horns

Push rods being assembled

Completed assembly

[cymaz]

Really inginious

[PeterF]

And here is the "proof of the pudding", or "Bob's your uncle". This has taken a bunch of time to design and build, some people probably put less effort into building a whole plane than I have done for this, but this kit deserves to have the time taken over it to get something just right. Sad old g**. The 5 photos show the gearbox from 90° behind neutral giving around 2¼" up aileron, through to 90° in front of neutral giving very little down aileron. However, the 4th photo shows the gearbox 45° in front of neutral, which gives around ½" up travel on the aileron, so the down going aileron goes down then comes back up just like the full scale. I have found figures that the full scale is something like 8 to 9" of up travel and 2" of down travel so my throws are spot on vs full scale. Chris states the model should be 1" up and ½" down and that the plane has a soft response. I expect mine to be OK because at mid travel I will have the 1" up and ½" down and then as the stick goes further over I will get more up but less down, so we will have to see how it behaves in the air.

I just hope my geometry calcs for the aileron servo and control arm in the cockpit are equally accurate and then it will all come together properly.

Full left stick, less than ¼" down travel

Half left stick, ½" down travel

Neutral

Half right stick, 1" up travel

Full right stick, 2¼" up travel

[PeterF]

Posted by cymaz on 26/04/2016 21:29:50:

Really inginious

Why thank you. If it helps motivate others / pass on ideas all the better.

[Michael Denest]

Nice job Peter. I can attest to getting (full size) TM ailerons rigged to the correct throws. I made a triangular aluminum template with a notch on one edge to engage the pushrod connection at the bellcrank. The trick is to have the chain and sprocket in the correct "timing" position when rigging the airplane. Even with all that aileron travel, it's slow to react.

[ron thornhill]

A superb job Peter I wish I had taken more time over mine now (too impatient).

I take it then that Chris has stopped trading or producing the TM, what a shame, it is a wonderful kit. I wonder how many he sold, could be a unique club.

[Tim Hurn]

I just met up with Chris in Chorley Wood to collect my kit. Can't fault the personal delivery service! We had a coffee and chatted aviation (full-size and Aero modelling). He is clearly trying to retire but planning to support anyone with a Falcon Kit as long as he is able. He has supplied about 40 altogether. He said he is still willing to supply parts that he makes in house. I did not ask but I suspect anyone wanting a full kit may be able to get one if they are quick.

[PeterF]

I have now almost finished the aileron actuation, by adding the pull pull wires. Sometimes I wonder why I did not just bang in 2 thin wing servos and be done with it,30 minutes work and done, and they could have been programmed to work like the real thing.

Anyway, I drilled a series of 4mm holes through the ribs for some 2mm ID 4mm OD nylon tube for the pull pull wires to run through. I have attached a short length of wire to the pulley with a 3mm screw. This grips the wire between a washer and the pulley to hold the two together. To make doubly sure that the wire will not slip it has been silver soldered to the washer. I made one up to test, washer in the vice and me pulling on the wire with some pliers, the pliers slipped off the wire before the joint gave way. I am happy it is there to stay. I have added some turnbuckles into the pull pull system close to the pulley where they will be able to be accessed if required via the inspection / maintenance hatches. At neutral they are a little to the side of the hatch, but when the aileron is moved fully one way or the other the turnbuckles move into reach through the hatch.

I have a question / want some advice. I now have the two wires coming out of each wing root and these will be connected to the control arms under the fuselage. However, the connections will need to be made and broken at the field as the wings are installed and removed. I could use normal clevises / quick links but that would not look very scale. Therefore I plan on doing the same as I did for the elevator cable connections and make up my own thimble and shackle from steel plate as that will be per full scale. The shackle will then need attaching to the control arms. I could have nuts and bolts, but these would need to be undone every time for 4 wires. Thinking about this, I thought I could use the same sort of cotter pins as used on the flying wires. These are held in with split pins, which would be fiddly but positive locking, so I made my own spring clip up with 0.9mm piano wire as per the photos. This will hold the cotter pin in place. I have seen these called P clips or R clips.

The question is, would you be happy with such a cotter pin and spring clip arrangement holding your aileron pull pull wires to the control arms.

 

Nylon tubes and pull pull wires installed

Turnbuckles

Wire attached to pulley

Control arms under fuselage

Elevator thimble and home made steel clevis

Home made spring clip (P clip / R clip)

Home made spring clip attached to cotter pin from flying wires.

Edited By PeterF on 30/04/2016 20:59:38

[Manish Chandrayan]

Excellent job there Peter. I am sure those pins would be more than enough and also make connecting and disconnecting at field easy. However let's also hear what others have to say about the arrangement.

Another but more laborious way could be to use the Mick Reeves fork ends and solder the wire ends to the fork ends. These fork ends have a securing screw. A longer screw could be used with the tail drilled to take a split cotter pin (to ensure the screws can not vibrate out).

[Pup Cam]

Great build Peter! - I partiicularly like the duplication of the fullsize's aileron operation to give the correct differential response.

With regard to your elevator control cables; where did you get your miniature cable thimbles from please? - I need some 1/3 scale versions.

Alan

[PeterF]

Alan,

Thank you for the comments. The thimbles are home made, to see how I made them, look on page 9 of this build log. They were quite eay to make, but fir larger wire bending a larger tube will be more difficult, you could anneal it before bending.

Peter.

[Pup Cam]

Thanks Peter, I see.

Richard (from Perfect Pilots) used a similar technique for the ones he used on his Flair Tiger I seem to recall.

There's nothing for it then; yet more metalwork!

Alan

[PeterF]

I have now finished the aileron pull pull cables. I have not yet decided how I am going to attach them to the fuselage control arms, at present I have just put some 8BA nuts and bolts on to get everything set up. I have made some more brass thimbles and steel shackles as I did for the elevators. I made 4 together in a sandwich to get them the same. Notice that when filed to size, I put rounded corners on what will be the inside that the thimbles rubs against, better than leaving square edges. The plane was once again ties up to the bench in the vertical position to set the wires up, the ailerons clamped into the neutral position, the servo set in neutral from the transmitter and receiver. I did try my servo tester but that had a different neutral point to my Tx - beware cheap servo testers. All rigged up and working per scale, really pleased.

I will be leaving the plane here for a while, I have some repairs to do on other air frames and some other bits an pieces.

4 shackles being filed to shape

4 shackles, note the rounded edges, these will bear against the thimbles

4 shackles and 4 thimbles

Plane set up for adjusting the pull pull cables

Ailerons locked in neutral

Turnbuckles wired in position once everything has been set.

Control arms / cable connections under the fuselage

Control arms / cable connections under the fuselage

Edited By PeterF on 02/05/2016 15:51:25

[Pup Cam]

Peter, not sure if you are aware of this useful set of documents:

**LINK**

Alan

Edited By Pup Cam on 02/05/2016 16:38:22

[PeterF]

Alan,

Thanks for that, I had not found that before. Perhaps I will spoil myself with a 6 month subscription to get a saved copy of everything.

Peter.

[Manish Chandrayan]

Peter,

With regard to your query on connecting the aileron wires under the fuse, would this type of shackle and pin system work for you?These are 3D printed shackles that a gent was showing on RCSB (same material as my aileron disc experiment, made of steel and bronze and plenty strong)

Edited By Manish Chandrayan on 12/05/2016 15:59:56

[PeterF]

Here is a video of the ailerons all working very nicely if I may say so myself. The down going action is pretty close to full scale I believe, perhaps it does not quite return to neutral, but I can live with that. To try and make it return to neutral would require me to strip down th gear boxes and change the flats filed onto the shafts, and I am not planning on doing that now everything is so good. The up going movement is 2.5" which is 25% of full scale and the down going is about 3/4", which again is scale.