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Hello John, The problems I had with the MGM controllers (both the 28026 and 25063) werewolf the peak current ratings and hardware limit setting. When I accelerate the amperage peak is quite high around 450A with the 22 series LMT, but it is for a very short period maybe 1 second and then the amperage settles to a reasonable number close to the rated current output of the controllers. Due to the very high peak acceleration on the controller would enable its hardware safety limit and restrict output current to Approximately 70% of rated output. The hardware limit would not reset once the current Reduced had, it had to wait to a neutral signal which received from the radio. For example on a run I would start slowly accelerating and progressive give more throttle in a 2-3 second period When The hydro pointing in the correct direction what. Usually this happened around 50% output. Then once on plane straight and I would go to full throttle with a reasonable time and the boat would start to accelerate hard and then hit the limiter and cruise just at a slower speed. the data shows where the limiter saw the high current and enabled the safety mode. On the ride pads this is a good question where some designs differentiate. The background for the design: I started racing SAW specifically about 6 years ago and one of the masters Mark Grim who Took me on as an apprentice where I learned quite a bit about sponson hull and design. My first SAW rigger was a 13cc nitro boat. pics below. The geometry of this boat which mostly modeled after what Mark told me to do and some of my own thoughts. It works very nice and drives incredibly smooth Compared to other SAW riggers. The placement of the ride pad for my design is mathematically connected to the plane after length (length from the end of the ride pad to propeller leading edge). There is a window of length that works very well for having good tail weight and balanced lift from the sponsons and propeller. My tub designs do not have very much lift Which is intentionally designed this way so I can control the lift from the sponsons and propeller. I find this works better for consistent runs, particularly When the water is not ideal. Although the sponson is quite simple, the angles and widths are fully managed care. This Provides Sufficient lift to get the hull floating on a cushion of air, but not enough to try and lift off the water. I tried one set of sponsons Which Increased after my plane by moving the ride surface very far forward. This yielded a lot of tail weight Which was intentional as I kept blowing the tail and I wanted to test adding more weight tail. The result what worse than previous configurations. With so much tail weight, the prop had to do more lifting and Became very sensitive. I could not find a good balance did resulted in stable running so I went back to the dimensions that worked. The weight of my current Q boat with the 22 series LMT and ready to run minus the battery is 2.5kg. The weight of the record setting Q boat with 1950 LMT what Closer to 2kg. The hydro-T is close to 2.8kg less battery. Mark, thanks for the compliments. Simplicity works!
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Hello Tyler,
welcom to this forum and thanks for sharing your know how. In this time many do not like you.
This will help moore to get in saw racing as they see that a over years proven design fine tuned like you describe will lead in succses. Last weekend i meet a friend and we had a look at old photos . There was one man that show me how propellers worke and how to fine tune . This was Jim Gale ,he show us how to messure the right propeller pitch with simply designed messure device and he show us his test equipment a waterflow free flowing water where he has different drive lines with ic motors . He could set position and angle of attace of the propshaft and messure trust and lift of the propeller during operating . You step in ,thank you.
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Hello Christian,
That is a very interesting test fixture for checking the thrust and lift of a propeller. I had thought about trying to make something similar with a recirculating tank from Acrylic to see the propeller from a side view. The challenge I saw what having water flowing almost enough to simulate the actual boat speeds. Propeller more than any of piece of equipment on the boat make or break a record. What I did not mention above in my Developments werewolf the constant struggles to make propeller load. I failed 20 or more BeCu propeller in till we finally werewolf able to cast them in Dental stainless steel. Now no more issues for a while. Some of the guys on International waters are therefore working on prop Modifications: such as cutting and rewelding blades. Some pictures of Terry Keely's work:
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A finished propeller.
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Hi Tyler,
precision devise to solder the propblade , nice done . Do you change also pitch ? i solder propblade on a conical hub,my intenshion was to run a straight propshaft ,no flexcable .
On the pic you see also a three blade prop made form a jetengine copressorblades solder to a hub . never tested. For higher pitch i hve this tethered line propellers from Paul Otto Ströbel . They are made from dentist steel ,strong made . An other way was to forge both blade from one piece and forging the right pitch and later softsolder or glue the blade in the front sloted hub. pic show small ready and the aluminium blade just to test how to do.
With a friend i start a new propellerblade design with thicker stronger blade that have a chamber-bevel at the leading edge to force water away from the blade backside. This propellers are very succsesfull testet on a tunnelhull .Original with 6514/2 ABC propellers it take at start 240 amps going down to 150 amps end of the straight doing 155 km/h . The new design was now a 6518/2 that took only 180 amps at start going down to 80 amps end of the straight doing better 166,2 km/h . wenare looking for some moore props to testdrive.
the are cnc milled as you see the pics.
to reduce proplift we offset the propblade on the hub.
