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The best kind of "working" vacation... @ Montague Glider Festival
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One word of warning Scott, we used to sell Carbon Brake Discs for RC Cars and when they wear to a certain point the explode into thousands of fragments, quite impressiveOriginally posted by MarnochS View Post
Jeremy and Ben
SCC
AAA TT TN
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I am taking my time putting together my Bidule 170. I am standing on the shoulders of aero towing giants so to speak. Incorporating the mods that others have made.
I wanted to share my take on the servo saver bracket and also the motor mount and steering arm angle replacement.Comment
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Scott, I stumbled across your excellent Bidule build thread while looking for a replacement for my Pegasus II. After 1,000+ tows, I lost my Pegasus this year at our club's Soar Utah aero-tow event. I added hydraulic disc brakes a few years ago, that I designed in Solid Works. I used the largest Sullivan Skylite wheels (8") and designed the brake hubs to fit the Sullivan bolt pattern. The wheels and brakes have worked flawlessly over the last few years. Interestingly, the wheels and brakes survived the crash, so I'm thinking of re-using them on a new Bidule 170.Comment
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HI Tom,
Nice looking brakes and sorry to here of the Pegasus's fate.....
You won't be disappointed in the Bidule's performance .....very stable platform. As Len say's "Production Towing"
At the last Visalia Aerotow, we had a weather front move through, the kind that stirs up all the dirt on the ground and throws it in the air.....well guess who was in the air...to add to the fun, there is a line of big trees on the up wind side of the field that was inducing a good rotor at the approach end of the field. The Bidule found this to be no problem at all......no flap landing and a little higher air speed.......Tri-cycle gear and brakes are a beautiful thing......
ScottComment
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My brakes were so effective that I had to be very careful during throttle up or quick application while moving to prevent a nose-over. I moved the landing gear forward a smidgeon and this helped. Ultimately, I allowed a small air bubble in the hydraulic line and it gave the brakes an "expo feel". All of this wouldn't be necessary with the tricycle landing gear.Originally posted by MarnochS View Post
The Bidule really looks to be a good fit and think that I'm close to pulling the trigger.
Are you still taking off in the parking area of Visalia's field? I haven't flown in Visalia's Fall Soaring Fest for several years.
Tom HoopesComment
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Hi Tom.
You built a nice set of brakes.
The Peg is a pretty good tug over the years, but wait until you fly a Bidule. The ground handling, slow flight and overall performance blows away any tug. I have 154 hrs of towing time on mine now and I can tell you its a durable and dependable tug. The brakes make it that much better, especially when there are 10 guys in line and you don't need to turn around and taxi back for the next guy.
There are only a few improvements you should make and you'll be in the air in no time.
Good luck if you go this way, you won't be disapointed.
Len
BTW, what happened to the Peg?
Len Buffinton
Team Horizon HobbyComment
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Hi Len,Originally posted by lenb View Post
I had just released a sailplane around 2,000' after a quick dozen tows. It was a normal descent (1/4 throttle, 1/3rd flap). The Pegasus started flying a tighter turn and was no longer responding. I moved the transmitter around every axis as the plane now pointed nose toward the ground with 400' to go. I remained cool as a cucumber as I tried everything to regain control. Just before the Pegasus piled in, I clearly heard the telemetry report 4.99 volts.
We fly on a dry lake bed about 1-2 miles from the edge of the Great Salt Lake. The ground is just like the Bonneville Salt Flats in that is absolutely flat and smooth, but the ground is soft an inch below the surface due to the high water table, consequently; it's pretty forgiving to hard landings and prop strikes. The Pegasus buried the DA-100 completely into the ground until the leading edges of the wing finally stopped its journey to the center of the earth.
Needless to say, there was no much left of the fuselage, although the wings were remarkably intact. Oh yea, my landing gear and disc brakes appeared to nearly be untouched. I'm curious to see what Desert Aircraft says about the DA-100.
I'm an engineer and own an engineering firm, so I attempted to perform a typical failure analysis if only to put my mind to rest.
My Pegasus had a shock-mounted Smart-Fly Power Expander panel. The receiver (Hitec Optima controlled by a JR-10X using a Hitec 2.4Ghz module) was mounted on the Power panel and all of the cables were routed through a large grommet on the fuselage tray. The dual BODA antennas were mounted out-of-phase with one antenna mounted on the left side of the fuselage and the other antenna was mounted to the fuselage bulkhead.
After modeling the tray, power panel, cabling, and receiver I found that the tray was oscillating (resonant) between 1200hz - 1800hz. Further the tray's movement pivoted at the point where the cables entered the grommet. This movement caused the opposite edge of the power panel to have substantial movement during oscillation. This was also the edge that the antenna coaxial cables exited the Optima receiver housing.
Careful analysis of the antenna coaxial cables at the point of breakage, revealed conductor crystallization most likely due to work hardening.
My final conclusion was failure of the antenna coaxial cables due to the power panel's mechanical oscillation. Interestingly, with the receiver antenna cables removed, I was able to RECEIVE telemetry even though the radio would not control the servos.
I should have mounted the antennas to a V-mount to provide good diversity and attached the V-mount to the shock-mounted power panel, thus minimizing/eliminating the slow deterioration of the antenna coaxial cables due to vibration. I should have also enabled a receiver fail-safe although I could only guess if it would have helped.
I wish that the Pegasus was still being produced and I'd build another in a second. It was a reliable workhorse that was a joy to fly. Your comments on the Bidule confirm my next towplane selection. Thanks!
Tom
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Tom,
I started a Pegasus build a couple of years ago along with Kevin Kavaney. I came across a used one that was so reasonably priced, that I could not resist. A year or two later, another Pegasus showed up again with a good price tag. Needless to say, I finished my wings and that was it. Kevin did finish his 108% Pegasus and has a 150 on it.
We have plans here and we might be building another Pegasus. A club member has a CNC foam cutter for excellent wing cores.
If you really wanted to build another one, there are many of us that could assist? Of course, I was reading this thread because my 170 Bidule should be arriving this Friday! A man can never have enough tow planes!
TimComment
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Scott,
I see you used Hitecs for your servos. It looks like you used 5685's on some of your control surfaces (per your photos)? I am looking to outfit my Bidule 170 with Hitecs as well. Can you list which Hitecs you used for yours including your nose gear servo?
Thanks! TimComment
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Hi Tom,
Here's my list of high voltage servos.....running off 2S LiPo battery
1 Nose gear - HS 5765MH Torque: 277.74oz-in (20kg-cm) 347.17oz-in (25kg-cm) - 1/4 scale servo - using carbon rod and Traxxas 5525 ball link connectors
4 Ail / Flap - HS 7954SH Torque: 6.0v,333 oz/in, 7.4v, 403 oz/in
3 Elev / brake - HS 5585MH Torque: 194 oz-in (11 kg-cm) 236 oz-in (14 kg-cm)
4 Rud / Thro / Choke - HS 5685MH Torque: 6.0V, 157 oz-in (8.8 kg-cm)7.4V, 179 oz-in (10 kg-cm)
Scott
Nose gear servo install (recessed for push-rod clearance)
Attached FilesLast edited by MarnochS; 11-08-2016, 01:35 AM.Comment
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Scott,
You are not using a servo saver for the nose gear servo?
Tim (Tom)Comment
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Oops, sorry about the confusion Tim and Tom...........let me take the short hand approach to this ......
Hi Txx,
Nope, no servo saver.....went with Len's tag line of "bigger is better" ...in the form of the output gear size to deal with the steering stresses. The Bidule is very light on the nose gear. No issues so far, but just in-case I have a spare HS-5765MH on hand ..... and it makes for an easy replacement if necessary
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Last edited by MarnochS; 11-07-2016, 04:09 PM.Comment
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Watch out when using big(powerful) servo with carbonate or metal output shaft. If you are using a nylon servo arm, inspect them once in a while. Philippe almost lost his big tug last month in Visalia when the rudder servo arm slipped and cause the rudder neutral at 30 deg off center in the air. It turned out the nylon servo arm was rounded(worn out) by the metal spline of the output shaft. Nothing holding the arm from spinning other screw holding the servo arm on the servo.
Inspect your servo arms!
Brian
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