TopModel Bidule 170 ~ build thread by JimD

[JimD]

We finished the headers and canister mount on Monday and cut and fitted the cowling yesterday. The fuel tank was the last item on the list and we literally finished it at the field ten minutes before the first flight.

Test fitting the second header pipe...



First flight...



There are numerous things to report:
* first, the hydraulic brakes worked perfectly. They will keep the plane from moving at fast idle and slow it down and stop it on a long landing.
* second, the nose spring steering damper worked well also. Was able to steer and make tight turns but still has enough give to keep from beating up the servo.
* third, the DA-150 has plenty of power. We did a few tweaks and the engine ran strong at the top end and with a good slow idle on the bottom end.

[lenb]

The plane was pretty much flawless on its maiden flight today. Kudos to Jim for doing such a nice job getting it ready.
Smooth, strong and plenty of power.

[BobM]

Congratulations on the maiden.........your build is great Jim !

Sounds like the new brake system is a real winner as well..........very nice engineering on that. I know what I will be adding to my Bidule this season

[Stew2]

I should be maidening mine in April, putting 4 Bidules in rotation for towing, and with a few more tow planes showing up, we should be able to all tow for not much more than a tank's worth of time through a day!! That should help greatly with the longevity of equipment and allow for lots of glider time as well. All a win-win situation. Glad to hear all went well and the 150 is a good match for the airframe, it gives yet another option for power, and that is a good thing! Also glad to hear your steering system is working well. Kudos to Gunny for the superb brake design, never had a doubt that wouldn't work well though.

[Xroadie]

Looks great! I wish I could adapt Gunny's brakes to fit on my Carbon Cub

Pete

[gunny11]

I need to design brakes for Scott aka Stew2 for his trailer so it won't roll down the hill at Cumberland Lol! In the mean time a wheel chock should do. ;-)

Pete, the only way to find out is to send me first some detailed pictures of the gear with the wheel removed and inside of the wheel. Then if it looks do-able, then you would have to send me the complete undercarriage.

[Xroadie]

I need to design brakes for Scott aka Stew2 for his trailer so it won't roll down the hill at Cumberland Lol! In the mean time a wheel chock should do. ;-)

Pete, the only way to find out is to send me first some detailed pictures of the gear with the wheel removed and inside of the wheel. Then if it looks do-able, then you would have to send me the complete undercarriage.

That wouldn't be hard Gunny! I have an extra set of gear for the Carbon Cub....and the wheels are the same Aeroworks wheels that everyone is using on their Big Bidules

Pete

[Jeff D]

Congrats on the maiden Jim. Pretty soon Bidules are going to outnumber the Blaniks and ASW20's....

[JimD]

Very soon after the first flights, we determined that the HS-7954SH servo we were using for steering was not even close to being adequate. After consultation with Jeremy (aka Swiss1) of the Model Box, we installed a Spektrum S9020 steering servo. Designated as a surface servo, it is designed to handle the demands of steering 1/5-scale R/C trucks. It has massive torque, large physical size, and gears to match. In other words, the perfect choice for steering the Bidule 170 nose gear!

Power does not come without a penalty. We noticed that the rate of battery consumption increased considerably. What to do?

As with giant scale sailplane retract servos, we decided to driving this servo with a separate battery. This can be accomplished by making a simple wiring harness that uses the signal voltage and ground wire (yellow/black) from the receiver channel being used combined with the positive and ground wire (red/black) from the auxiliary battery (place a switch inline between this plug and the auxiliary battery). The S9020 steering servo then plugs into the 3-lead connector.

With this setup, the receiver battery drives the electronics in the servo and the auxiliary battery drives the motor in the servo.

[JimD]

When we added the Aviation Concepts Hydraulic Disc Brakes, the master cylinder and servo were mounted on a removable plywood platform. The 1/8" square sticks form a dam around the master cylinder to catch any overflow leaks when charging the brake system. The plywood platform was coated with thinned epoxy to protect it in case of a spill.

[JimD]

Although the Bidule 170 was designed with the DA-170 and DLE-170 engines in mind, we opted for the DA-150 after speaking at length with the DA folks at the WRAM Show last year. Again, at their recommendation, the prop chosen was a 2-blade Mejzlik 30x12. This engine and prop combination has worked beautifully and has provided plenty of power, excellent fuel economy, and very reasonable sound levels. That said, the prop does bark when flying at high throttle an no sailplane in tow.

After towing for the entire season of 2016 and logging over 50 hours of flight time, the DA-150 powered Bidule 170 has not only met my expectations, it has far exceeded them!



Now to build another one to match!

[JimD]

Bidule 170 #2

The one thing we opted to change on Bidule 170 #2 is the steering servo saver. The Losi parts that Scot and Len are using have proven to be the superior choice compared to my design. Since the Bidule 170 tends to be nose heavy, we decided to move the servo saver as far back as possible (as Len did on his Bidule 170 v2.0). We also decided to try and design a way to have access for service from the top of the fuselage. So, instead of incorporating the servo and saver into one unit using the aluminum L-stock, we mounted the parts separately.




The throttle and choke servos are mounted against the left side of the fuselage.

[JimD]

The header tank and ignition module are mounted on removable platforms and fit above the servos and steering servo saver.

[Stew2]

Jim, go with DOT5 fluid for the brake from the getgo, You will find it so much more user friendly. I'm going to switch my existing Bidule over to it this Spring and build my second Bidule with it also. I used DOT5 fluid in many antique car restorations and it is nice to have a brake fluid that you can about polish the car with instead of one that removes most every coating!! Really like the separate component install on the servo saver. So much easier. Have you had to change out the steering servo since installed the Spektrum one? Looking forward to flying 3 Bidules in formation this year, but I get to fly lead, we can stick Len in the middle!!.

[JimD]

I added a third spring to each side of my homemade servo saver which helped to make steering a bit more positive. As for the Spektrum S9020, the original servo continues to work just like the day I first installed it. I do have a spare just in case, however.

[JimD]

Fabricated parts for a removable fuel tank support for DuBro 100oz tank.






Fuel tank is centered on the CG so fuel depletion does not change balance point.