Hi Now at point of locating the throttle control and found I could not put what I had for a throttle control in the location I wanted to put it. I wanted to put it to the left of my left thigh, inside the cockpit, rather than up on the flat top deck area. The type I had, so wanted to reuse, is the one fabricated from a couple of plates of aluminum with a nice fore and aft moving handle, one is pictured below(it has two arms, mine had one). There just was not room for it to the left of my thigh, and it is not the right design for flat top deck mounting. The second one I have is the compact, rotating one also pictured below, but I did not like the constant circular flexing of the cable. The other picture is a normal, dash mount type push pull cable. Pretty standard stuff. I guess I want to see if I am in fact omitting some choices here. I think a flat topped deck mounted control has merit in that you can rest your arm on the fuselage side member. All ideas and photos are greatly appreciated. Thank you. Kim Brown
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What is the radius of the wheel in the second one? if you are about 2"-2.5" on it it should be fine for the cable if it is a 1/16" cable as most are. That is less stress on the cable than what we see in some control systems. I personally use something like AS part #05-02420 for my throttle only and the same series for 2 or 3 controls as needed. They are simple and reliable. one option may be to install a push pull like you have on the bottom of the list into some 2" Angle of 1/8" thickness just under the dashboard to the left side, sort of above your left knee. That may be comfortable.
See my throttle control pic in my rudder help post recently.
Here's a link to the page from my build thread, where I was asking about throttle options and examples. The examples shown might give you some ideas of your own....they really helped me out. Also here's a link to what I ended up building and installing. I looked for the photo itself but couldn't find it so please click on the link below. I'm pleased to report it works nicely and feels about like what I had hoped for. I think the photo of mine is in post number 228, which is the second from last post on the page.
Here you can see an early build photo with the throttle mount installed for a quadrant-style throttle. My knee hits the superstructure under the deck if I swing it over to that side. My body never touches the throttle assembly.
My throttle doesn't stay in place very well. The two carb springs pull it back. I tried using an engraver to "ping" both sides of a washer and that helped for a little while but I think I'm going to have to fix something like a wing nut on the outside of the lever so that I can tighten down on the lever once I'm set for cruise. I have some more important things to get right before trying that however, like wiring the strobe light and doing the annual inspection.
Here's hoping I end up with something that looks as nice as yours.
Sterling Silver.....Thanks for the compliment. As I recall, I bought some fiber washers in the aviation department at the local True Value Hardware and put them on both sides of the lever to provide friction. It took some fine tuning, but so far they have held throttle position nicely without needing excessive drag on moving the lever. I did use a nyloc nut to make sure the adjustment didn't "self-adjust" with usage.
Sterling Silver.....Thanks for the compliment. As I recall, I bought some fiber washers in the aviation department at the local True Value Hardware and put them on both sides of the lever to provide friction. It took some fine tuning, but so far they have held throttle position nicely without needing excessive drag on moving the lever. I did use a nyloc nut to make sure the adjustment didn't "self-adjust" with usage.
Lynn
There's one of those specialty stores on the other side of the airport. I'll check with them; don't know why I didn't think of a simple source.
I made my own, just using a bit of flat bar. The friction control is the large wooden knob at the pivot, with a couple of fibre washers each side, and a nut epoxied into the centre. The pivot itself is a 1/4" bolt rigidly mounted to the fuse side panel.
I found the throttle tended to close in service, despite the friction clamp, so I counterbalanced the carb spring tension with a length of bungee cord which tries to pull the throttle forward. I played around with length until I got it right.
This system works well in flight, although I tend to fly with my hand continually on the throttle - it's in a comfortable position for resting my forearm on my thigh. Note I fitted the throttle on the right hand side, as I am left handed & prefer using my left hand on the stick.
I made my own, just using a bit of flat bar. The friction control is the large wooden knob at the pivot, with a couple of fibre washers each side, and a nut epoxied into the centre. The pivot itself is a 1/4" bolt rigidly mounted to the fuse side panel.
I found the throttle tended to close in service, despite the friction clamp, so I counterbalanced the carb spring tension with a length of bungee cord which tries to pull the throttle forward. I played around with length until I got it right.
This system works well in flight, although I tend to fly with my hand continually on the throttle - it's in a comfortable position for resting my forearm on my thigh. Note I fitted the throttle on the right hand side, as I am left handed & prefer using my left hand on the stick.
I like the way you did the friction adjustment; that looks nice. The bungee counterbalance seems like a good idea as well. Getting the length right seems like a good reason to make a bunch of test flights.
The heel brake pedals look more serviceable than the ones in the Taylorcraft that I used to fly.
I have a question or two for you regarding the photo you sent to this thread on March 8th It shows something I am curious about so I want to ask what it is. In the forward section of the left side of the inner fuselage, you have what appears to be a double wall area, that tapers from the floor up to the top, near perhaps the firewall. In this upward tapering double wall area, there are four bolts near the lower longeron. So I have two questions on this subject:
1. what is the double wall area all about, is it reinforcement for the firewall perhaps?
2. the four bolts near the lower longeron in the area where perhaps one would put a foot mount or something on the outside, do they in fact hold an external foot mount to use when getting in the plane? If so, perhaps that is one way I could address my interest in not having the foot mount come into the plane.
I think you are referencing my photo. My build was indeed VERY experimental. To this day I may still hold the record for the most powerful engine ever installed and flown (albeit very briefly) in a 560 lb. gross weight Minimax. One photo shows the 90 HP Suzuki water-cooled engine installed as flown. The other photo shows the custom built radiator and what's attached to the four bolts you referenced on the inside of the cockpit - an Aluminum step.
My unassuming Max is rife with mods, some visible, some not - including an extended and strengthened fuselage that also incorporates some mods from the then-new VW builds just beginning to show up, a beefed up engine area that uses doweled hardwood joint fillets, and a double wall construction that was recommended by TEAM at the time for those who were installing Rotax 532's. Many of these mods addressed the expected increased landing loads. My Suzuki engine was virtually identical in size and weight to a Rotax 582, but was more powerful.
The Suzuki (which had flown on my Experimental gyro) turned out to be totally inappropriate for an airplane (and thus the 503 it flies with today). But then, I was young and dumb, and knew very little about 2-stroke engines. This explains how it can take someone 20 years to get a homebuilt flying, and why, these days, I advocate doing things according to the designer, especially if you want to get airborne in a reasonable amount of time. Perhaps the most amazing thing about my story is that I actually lived to tell it!
Hi That photo showing the aluminum step from the outside is just what the doctor ordered!! I even have a piece of aluminum in my scrap bin that will work just fine, I'll make a determination of how much backer board to use and do it just like yours. I like it!! Thanks. Kim Brown
I like the way you did the friction adjustment; that looks nice. The bungee counterbalance seems like a good idea as well. Getting the length right seems like a good reason to make a bunch of test flights.
The heel brake pedals look more serviceable than the ones in the Taylorcraft that I used to fly.
Any excuse for a bunch of test flights! In fact, I regard every flight at my low Max hours as a 'test flight'. I'm still experimenting with flap positions, and haven't yet been bold enough to kill the engine at 1000' & glide down for a genuine deadstick landing. But I've always found the learning stage to be every bit as enjoyable as when you've cracked it: every flight is still an adventure for me!
The heel brakes are ok to use, but the brakes are not particularly effective. With maximum pedal effort I can only rev to about 4000 rpm on pre-takeoff power test, and they're a bit marginal to use in assisting directional control on landing. They are useful for tight turns at low speed.
The heel brakes are ok to use, but the brakes are not particularly effective. With maximum pedal effort I can only rev to about 4000 rpm on pre-takeoff power test, and they're a bit marginal to use in assisting directional control on landing. They are useful for tight turns at low speed.
Bruce
As I remember, that about describes the band brakes on a 1946 Taylorcraft BC12-D, which is my experience with heal brakes.
Push to open (maximum throttle) or pull to open (maximum throttle)?
If your airplane uses a 2 stroke with slide carbs you would need a bellcrank to reverse the throttle movement if you want to stay with the standard push forward for more power. You might be better off and cheaper to go with a throttle like Bruce shows in his post above and either go with one cable off the throttle arm that goes to a splitter or run 2 cables off the throttle arm, one for each carb.
I think you are referencing my photo. My build was indeed VERY experimental. To this day I may still hold the record for the most powerful engine ever installed and flown (albeit very briefly) in a 560 lb. gross weight Minimax. ....
....The Suzuki (which had flown on my Experimental gyro) turned out to be totally inappropriate for an airplane
.... Perhaps the most amazing thing about my story is that I actually lived to tell it!
12 hours on and no-one has bitten??? Well I'm biting.
How can you, Bill, tease us with pictures of the meanest looking Minimax I've ever seen, tell us it was a mistake, and then not say why?
Performance and handling report please ...and that's an order.
[I'm sure you will find a way to mitigate this blatant attempt at thread drift....]
Antoni, A 90 hp water-cooled Suzuki snowmobile engine powered my first EAB aircraft, a kit-built Eagle Gyroplane. In 1988 it offered things other 2-strokes did not, like electronic ignition, oil injection, adjustable main jets, and a Rotax gearbox custom fitted to the engine by the supplier of the engine package (this would almost kill me later when the gearbox partially separated from the engine in flight due to the fabricators failure to drill proper mounting holes in the Suzuki's crankcase). Oddly, because the kit supplied one of the most powerful engines then available for a kit Gyro, it sported the name - "Black Max."
To this point, the only 2-stroke experience I had was with motorcycles. The concept of 90 HP was very appealing, especially on a draggy machine like an open-frame Gyro, and also because I flew from a 7000' elevation. In fact, the engine spent most of it's flight time in the upper 1/4 of the RPM range to overcome the drag (calculated at the time to be equivalent to about 2-square feet of flat plate area), so I had little feeling for how much torque was available at lower RPM ranges. This would turn out to be critical later on my Max.
The engine was indeed powerful at high RPMs, around 8200 stock, as on my Gyro, or up around 10,000 if you were racing it in a snowmobile! I'll never forget the scary thrill that happened every time that engine suddenly ramped up at 7600 RPM and shoved me back into the seat. It made me aware that although flight speed was only around 55 MPH, I was sitting astride a real monster!
But the major failure of this same engine when installed in my Max was the fact that there was virtually no useful torque available below that 7600 RPM point. This made operation in an airplane virtually impossible because it became, essentially, a power-on/power-off situation. Yeah...akin to a Sopwith Camel! Even with the theoretical power available, I only made two test trips around the pattern, barely able to remain airborne and get back around to the runway. I never really understood why, but in retrospect I figured the relatively small prop disc just wasn't able to provide sufficient thrust - likely proving that my Max had even more drag than the Gyroplane! The end of that story came when, in spite of the water cooling, and a gorgeous hand-fabricated radiator, which I was very proud of, and was one of the most complex components I ever fitted to my Max - I cooked both pistons! Probably during one of my many ground tests. Thus, after 18 years of construction, I ended up having to swap out the Suzuki for the 503 (and deal with the FAA again) before I ended up with a flyable airplane.
After 8 years of successful Max flying I just recently pulled the plug and decided to quit flying. There were many reasons. Two main reasons were that my deteriorated age-related vision was becoming a concern, and I was also conscious, as wear began showing up in several components, that parts of this airframe were now 28 years old. I had begun to think a lot about those epoxy joints! The final impetus though occurred during my last flight.
I was returning to the airport, and was about two miles out when my EGT's suddenly began to climb above the 1200 degree limit. I fully expected that I was going to have to find a place to set her down in the next few seconds! I throttled up full to gain extra cooling and was able to make it through a short, desperate pattern and get it safely on the ground. This was the first time this engine had ever failed me. I was unable to find an obvious cause, and believe the most likely culprit is probably a crankcase or gasket air leak. In any case, it would likely require a tear-down and diagnosis. Combined with the previous decision to make this season my last due to my vision, this was the final blow. I do not have the experience, the tools, or a facility to tackle this myself, and no local Rotax shops are available where I live. I also have no desire to spend what is likely to be a considerable amount of money to repair an engine that I was probably only going to fly for one more summer.
Like most things, this did not pan out the way I was imagining it would. Due to potential liability my Max will not be sold. At this time there is a potential deal in the works for it to spend the rest of it's life hanging from a Museum ceiling as an exhibit. It's a bit sad for me, but it's all part of the acceptance required of aging. The way I see it is that this wonderful little machine, built with my own two hands in a garage, was able to satisfy my dreams of simple flight for more than eight years, and I survived to tell the tale! I'm really a very lucky dude.
So you never even got the chance to see the performance at ~90 hp Bill.
I'm imagining you slowly advancing the throttle to begin the take-off run with the engine picking up a bit, then toward full position it suddenly spins up to nearly full RPM. Then you back it off a bit and it suddenly returns to next to no power / RPM because the torque available at lower RPM isn't enough for the load demanded by the prop at a medium RPM. Sorry to repeat what you wrote but hope I got that right.
I had a very similar experience when a spark plug departed my previous Minimax's 447. Not far from the strip. On full throttle, with some power absorbtion from the dead cylinder there was just enough torque to keep the prop spinning for a gentle descent at modest airspeed. Slowing down a bit for final to our short strip the engine RPM suddenly fell back to a rough idle while still on nearly full throttle. in short, the prop fell off the back of the engine's remaining torque curve. Landed uneventfully in a ploughed field short of the threshold, very tailwheel first because I was crossing the 12 inch furrows.
In my defence, I'm still sort of talking about throttle controls and what happens when you operate them....
One caution: If using a Rotax with Bing carbs, make sure that whatever quadrant you end up with, you are able to detach the quadrant-side cable attachments. Otherwise you will have great difficulty removing the slides for repairs or adjustments of the slide needles, because you will be unable to release the cable tension.
Interesting story Bill. Nothing to worry about epoxy joints unless... My Max always tends to reach the 1200 egt limit I one cyl only I’ve learned how to deal with it changing throttle setting or flying with a bigger angle of attack. After a while it settles so I think is just a bad reading. I’m sorry you had to quit flying for those other reasons, we just hope you still hang around in this site making your always interesting comments.
Interesting story Bill. Nothing to worry about epoxy joints unless... My Max always tends to reach the 1200 egt limit I one cyl only I’ve learned how to deal with it changing throttle setting or flying with a bigger angle of attack. After a while it settles so I think is just a bad reading. I’m sorry you had to quit flying for those other reasons, we just hope you still hang around in this site making your always interesting comments.
Thanks Ricardo. I typically saw EGT's sit near 1200, but they consistently did so as I changed jets for differing conditions. I worried about it a lot, but plug readings were always good and the inside of the engine - pistons/rings always looked clean, with no carbon build-up. I could always bring the temps down by running richer, but I was shooting for 400 hrs (at which point I would sell it or decide to rebuild it). without opening up the engine or de-carbonizing, per the recommendations of Brian Carpenter on how to get the best use out of these engines. Haven't tallied up the hours lately, but I don't think I have even hit 200 hrs.
My incident was very sudden and specific, with the EGT temps suddenly going up a couple hundred degrees within a few seconds. I didn't take time to try and diagnose things. I knew the engine would likely only have a few seconds before disaster struck, and with the airport only a couple miles away and 1400 ft. in the bank, I quickly throttled up to open the main jets all the way and dove for the airport. In spite of a faster than normal approach, I was able to get it down and taxi all the way back to the hanger (probably a good half mile) with the engine still running.
The quick temp rise seemed to announce some type of sudden and serious failure. I experienced the sudden loss of crankcase integrity in flight on my Suzuki 2-stroke. the result was that I had the choice of full throttle or idle - nothing in between. I was afraid the Rotax had suffered a similar fate. nonetheless, I did a series of checks and adjustments, During which I discovered that my jet needles were both attached to the highest clip position, which would have caused lean running. This could have accounted for the relatively high EGT's I had been seeing in cruise. How and why they were set up that way I don't know. I must have dumbly done it myself at some point. In any case, my constant jet changes seemed to compensate and perhaps avoided disaster. I did find a somewhat wet looking oil leak at the rear cylinder base - an air leak? An A&P friend with some 2-stroke experienced thought it unlikely. Nothing was evident around the crankcase itself. I added new plugs and checked everything else I could think of - to no avail. When I cranked it up again, with the intention of maybe flying a pattern or two, it ran very roughly and wouldn't even throttle up very far. Game over.
With my deteriorating vision, I had thought I might see the current summer season through and then call it quits. With the engine now suddenly requiring some serious and possibly expensive diagnostics and repair, I couldn't justify spending what would likely be a big tab for repairs, especially since I would have to ship the engine somewhere to have it done.
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