Bidule 170 - What we've learned - Build thread, Len

[lenb]

The brake system is hydraulic and needs to be refilled from time to time, doing this can get messy if the hose pops off ( experience talking here )
So this time I made a little tray for the brake systems master cylinder and servo to live in, then coated it with West Systems epoxy which was thinned out.

This was mounted to a couple blocks I installed to the bulkheads.






Onto the tow release.

On the previous Bidule, there would be times when the tow line would get wrapped around the front side of the tow release and when released it would stay hung up on the front side. Luckily this never happened in flight, but we're not taking any chances.

[lenb]

Tank mount.

We need to make our own tank mount for this plane. Top Models wants you to mount it up on the forward platform, but we carry 114 oz and it would be really nose heavy at full fuel with a constant CG change throughout the flight. I made a new tank platform and positioned the center of the tank just about over the CG. I held it slightly forward so I can get my hand down to the rear wing bolt.



A simple upright support epoxied to the LG plate will hold the aft end up and the front side is bolted to the servo saver frame. I pre planned this out, so the servo saver height is correct for supporting this platform.







Our header tank is nestled in nicely just aft of the CG, on top of the LG plate.

[lenb]

Backing up a bit, I neglected to cover how I fit the brake cylinder into the fuse.
As in the previous plane, an easy modification to the rear platform will yield all sorts of room AFT of the CG for the brake system



This shows the quick hardwood frame I'm going to glue UNDER the edges of the cut out platform

[kjkavaney]

WOW...THis thread is so much better than any build manual ever...This is so incredibly helpful for those of us who are a just getting going on our Bidule build...your foresights on things really save the day...Thank everyone of you so much...especially Len for so many revealing pictures along with text...
Kevin

[lenb]

Hi Kevin
Glad you are getting some ideas out of this. If you have anything specific you need help with, please feel free to ask.

Len

[AureleAlain]

Hi Len,

Thanks for posting this. I have 2 Bidules (Bidule 55 and 111) sitting in my spare bedroom right this second. The Bidule 55 will be electrified. I'm glad I didn't start on them sooner..

Aurele

[lenb]

HI Aurele,
That should be a fun little tug with an electric setup.
Be sure to check out Jim's Bidule 111 build thread too. http://forum.scalesoaring.com/forum/tugs-and-stuff/tow-planes/13964-bidule-111-v2-0


Since the cold has arrived, it's time to get those boxes out and start building!!

[lenb]

Our tasks are winding down in the fuse, so its time to figure out the radio installation. The receiver will sit just in front of the tow release, with the batteries to the left and right of the brake master cylinder setup. To hold the batteries in nice and secure, I make up a lite ply plate which has a channel under it for velcro to pass under. There are three batteries, two flight pack and one for ignition.








My servo extension leads for the dual rudders are joined together in the tail in one simple positive lock connector. These are available from Hansen Hobbies.http://www.hansenhobbies.com/product...nlpconnectors/

Since they come in many different combinations which will take 3-6-9-12or even 15 wires, you can make all your connections with one simple click. The beauty of these connectors is there is no soldering.

[lenb]

Landing Gear Modification

The carbon main landing gear on this plane is excellent, so this modification has nothing to do with strength, instead its about appearance. With the addition of brakes on a Bidule you have to have tubing running down to the brake caliper. Unfortunately, its pretty unsightly since you need to tape it to the landing gear leg, which then gets greasy and starts to come off. Yuk. I'm tired of it.
My solution was to add a carbon fiber tube down the trailing edge of the gear.

Step one was to sand the paint off the gear TE, this took about 2 minutes. The paint is fairly brittle and sands easily and to my surprise, there's a lot of filler under the paint.


The carbon tubes were cut and left a bit long on the top side. The tube I used was a Dave Brown carbon fiber pushrod. The pushrod is abut 1/4" so its important to hold the the top of the pushrot to the top of the gear down by the wheel and to the bottom edge of the gear up by the fuse. This will allow the tube to contact the fuse underneath and look really nice.
My go to epoxy for superior strength and ease of working is West Systems Epoxy. I mix it with 404, which is high density adhesive filler. Mix it to a past consistency and glue the tub on, taping it for the night.










After the initial gluing, it took three sessions to get the epoxy filled the way I wanted it, then one more tonight where I applied a layer of fiberglass cloth to the gear and around the tube.
Next I will spread some epoxy with 410 lightweight fill on the entire gear and sand it all smooth.

[lenb]

While waiting for epoxy to cure it was time to hinge the ailerons, flaps and elevators.

I took every hinge point out of the surfaces and threw them into the garbage, replacing them with Robart 3/16 Hinge points. Ask ANYONE who has used the stock hinges, they WILL fail. Simple as that.

I take the needed hinge points and lay them on a paper towel, them apply a drop of machine oil to the pivot point. This is all you need to keep them from sticking if epoxy gets on the joint.

Using G-flex epoxy, once again from West Systems, I mix up enough to install all the hinge points in the surfaces only.


Here's how I do it

Mix the epoxy,


Pour it into a small zip lock bag.



Clip a very small hole into the corner, making a frosting dispenser.





Use the dispenser to squirt the epoxy into the hole, no mess, no fuss.

Once in the hole, use a piece of wire to swirl it around inside the hole

Insert the hing points, making certain they are lined up and operating properly.



Set them so the epoxy will flow down over the hinge point on the inside.




Let them cure for the night and we'll install them into the wings tomorrow.

[lenb]

Hi Tim,
I did not add additional hinge points. After looking at he older Bidule control surfaces, there was no sign of fatigue or failure with the ROBART hinge points we used.
I elected to stay with the stock amount of hinge points, however its CRITICAL you change them over to ROBART Brand and then throw the other ones away.

[Steve P]

I think you mean Robart Hinge Points, not Sulivan... http://robart.com/collections/contro...inge-points-15

[lenb]

Yes, thanks Steve, I made the change. I did mean Robart Hinge Points.

[lenb]

Work has continued on the Bidule, but at a slower pace due to some work issues getting in the way of fun. The landing gear is finally finished, and it came out great. Getting the gear ready to paint was a long process because you fill a little, wait for it to cure, sand, fill, prime, sand, fill, prime, ...... I know its not a scale airplane, but its my nature to do the best I can on each piece.... It sometimes makes me crazy.





Before the final paint, I wanted to address the "flat spot" where the axle goes through. I stress " flat spot" because it's anything but flat... The axle area is rounded a bit and the thickness varies from top to bottom, which is fine when not using brakes, but when you want to install brakes there are attachment brackets which need to attach to the gear. A flat area would be so much better.



Grind off the paint and primer on both the inside and outside of this area, Fit the axle spacer Gunny provides in his Bidule Brake Kit http://www.aviationconceptsrc.com/hydraulic-disc-brakes

Make 4 flat plates out of G-10, 1/4" aircraft ply, aluminum, whatever you have but make sure its strong and smooth. Drill a hole in the middle the same size as a bolt that will pass through the axle bushing you have just installed. Cover one side of the plates with duct tape, this acts as a release tape and epoxy will not stick to it. ( trust me )

Mix up some high quality epoxy, I use WEST SYSTEMS , along with micro fibers. ( West Systems 403 ) The fibers act as a filler and thicken the batch while adding strength.




Apply the mix to the bearing provided in the brake kit and insert that as instructed

Apply the mix to both sides of the gear bottoms



The bolt you use to hold this all together must be lubricated so it does not glue in. I used some Vaseline liberally applied to the bolt. You do not want it to glue in!!!!

Once all the glue is applies, bolt the two plates on the gear and tighten the bolt GENTLY. Dont squeeze out all the filler. I brought the bolt tight enough to firm up, but found I needed to add a shim to the bottom outside plate. A small piece of hardwood will do the trick.






Wipe off any access and repeat for the other wheel.

Once cured (next day) Pop off the parts and check it out. The edged can all be sanded straight at this point. You will most likely need to apply one more coat of filler around the edges to make it perfect and fill in the area where the shim was.





You can see how much correction was made.

[lenb]

Install the brakes EXACTLY as instructed in the Aviation Concepts Bidule Brake Kit and you'll have no problems at all. Everything will fit perfectly.

[jgallacher]

With all the problems you guys have with the Nose gear, why not make it a tail draggers? Jim G

[JimD]

Jim,

Let me chime in here...EVERY tow plane has landing gear issues because of the number of takeoffs and landings they make. On the whole (and after 60 hours of personal experience with this aircraft) the landing gear has not been that much of a problem. If we can make it better and even more reliable, that is a good thing...and that is the point of this thread.

Aside from personal preference for tricycle gear vs. a taildragger, there is another point to consider...WIND. The plane sits level on its gear with the tricycle configuration whereas a taildragger sits nose high. Because of this, the wind has a much great chance of flipping the plane over...and again, I know this from personal experience.

Just my $0.02

[lenb]

Hi Jim, and Jim..

After figuring out the nose wheel servo saver issue, I would venture to say this plane is the has the least issue of any tugs I've ever owned. As stated above, the hours put on a tow plane far far far exceeds the normal sport flyer's use.
With the Bidules becoming so popular and so dependable, this is an attempt to make it bullet proof. The main gear is very good, but because is a carbon gear and we add brakes to it, I decided to "square things up" a bit.
I know, you can never leave good enough alone!!!
Straight out of the box, this tug will last a long time and do a fantastic job, but we'd have nothing to talk about if we all did that. ha ha

The tail wheel vs nose wheel thing has been hashed around, I was not a believer in the nose wheel and went into this with a bias toward tail draggers. I was wrong.
When towing for hours and hours in a day, the nose wheel setup requires a little less pilot attention and in the end eliminates some pilot fatigue. Plus as Jim D points out, it sure is nice in windy weather.
It's a bit like many things that once you try it you love it.

Have a nice holiday season

Len