I still need float-rigging info

[av8rps]

I just couldn't resist after stumbling on this old 1979 magazine last night...

[av8rps]

Ok, now that I'm done screwing around I will get serious...

In 1993 when I was trained to fly my Lake Amphibian, I was taught to always say out loud my landing intention and the landing gear position at least two or three times during the landing phase. This training is critical in any amphib, but ultra critical in a Lake because most gear down water landings result in fatalities. I paid special attention to that part of my training after I saw a picture of a Lake that landed in the water gear down. Everything forward of the wing was gone - it looked as if a bomb had gone off in the cabin! (for anyone that doesn't know what a Lake Amphib is, this link will not only show you what a Lake is, but also how the gear goes up and down for land and water ops https://www.youtube.com/watch?v=2Hxh_8EEohc [see if you notice a little dog while you're at it] )

So getting back to my procedures for proper gear position, here is an example of what I do when flying my Lake Amphibian that can be applied to most any amphib;

At an airport landing on pavement, my first effort to check my gear position is when I initially enter the downwind for the landing pattern. Once I have all normal traffic duties accomplished I say out loud to myself "This is an airport landing, and the landing gear is going down" while reaching over and putting the gear handle into the down position. A few seconds later I look into the mirrors that are attached to the wing floats so I can look to see that the nose gear is actually in the down position, followed by a visual on each main gear (mains are easy to see on a Lake as they are right next to the cabin when down) and that my hydraulic pressure is up. Last, I verify the landing gear position by lightly touching the "Gear down" lights as well as the gear handle to make sure they indicate the gear is down and locked.

Then when I make my downwind to base turn, during the bank I again call out my gear position. But this time I also look into the mirror that is on the lowest wing so I can see the nosegear hanging down against the nice blue sky / horizon (much easier to see against a one color background than when the aircraft is level), while again checking my main gear visually, double checking that my hydraulic pressure is holding, then again verifying and touching my "gear down" indicator lights, and also lightly touching (but not grabbing) the gear down handle to verify its position.

Last, right after making my base to final turn, and once happy with my stabilized approach to the runway, I make a last landing gear check. Again I say out loud "This is an airport landing, and the landing gear is down", followed by one last visual check to make sure the gear is down, my hydraulic pressure is good, the gear down indicator lights are on, and the handle is down, all indicating the landing gear is in the down position and locked, ready for an airport landing.

For water landings, well before my approach to the water surface (when I still have plenty of time and space) I will call out loud "This is a water landing, the landing gear is up, I'm now a boat", while looking in my mirrors and banking to verify the nose gear position is "up" against the sky, then verifying visually the mains are up, hydraulic pressure is good, followed by a visual and touch verification of the "gear up" lights, and touching (but not grabbing) the gear handle to verify it is in the up position.

Then when I am on my final approach to the water landing, early in the approach I say one more time "This is a water landing, the gear is up, I'm now a boat", while again making a last visual check of the gear position, hydraulic pressure, and the gear up indicator lights, along with the gear handle.

As a personal rule, I always verify gear position before any landing. Even if I just took off from the water and plan to do a landing right after takeoff (also known as a "splash and dash"). Most seaplanes do not have an "Uplock" on their gear mechanism, so just imagine what might happen if on that last bouce off a wave that made you airborn, the gear unlocked for some odd reason? (... a hydraulic line that came undone, a gear link broke, etc.) You'd unknowingly splash down right after your takeoff with the gear down, spoiling a lot more than just your day!

So even though the Lake Amphib has a really nice uplock in its gear design, and so do my Aerocet floats on my Kitfox, what if for some reason or other it stopped working that day? Plus, because I often am flying other amphibs, I just make it a point to never assume the gear stayed up just because I thought it should. So again, I verify visually the actual gear position, even for splash and dashes.

Also, if you have a passenger with you don't be afraid to task them with making sure you are doing the right thing with the gear. I've found they like to know about that when explained to them, and that they like to help you keep an eye on it too (self preservation is a really strong instict apparently ). Just include it in your passenger pre-flight seaplane safety briefing (which you should always be doing anyhow).

And as far as using lights and hydraulic pressure, that is fine. But more importantly is actual visual verification of the landing gear position. My Kitfox amphib only has mirrors, no lights, and no hydraulics, being that it is a manual system operated mechanically by a Johnson bar. So I rely entirely on my mirrors. Many would say the Johnson bar is all you need, but what if a cable or a pulley inside the float that actuates the gear broke? My handle would show the gear up, but part of it could be down. So again, I trust my mirrors to visually show me where exactly my wheels are before any landing. Indicator lights and switches are prone to failing in a water environment, so I only consider them an additional, or backup to visually verifying gear position. The same goes for voice warning systems. They are only as good as the switches that actuate the gear lights - which is poor at best in my opinion.

Call me old fashioned, but I prefer to trust my eyes for knowing exactly where the gear is when flying an amphib. And if it just wasn't possible to do it effectively with mirrors, you'd be seeing me installing a small camera and video screen system in my plane so I could use that to visually verify my gear. They can be had for under a hundred bucks these days, and could be used for some cool seaplane video stuff as well (like this https://www.youtube.com/watch?v=j3kO2nZoSDA ). In fact I have thought about doing a camera system for a few years now, after installing a cheap backup camera on a camper a while ago and seeing how well it worked. But for now my mirrors still do a good job, so I'll keep what I have. But my next amphib (a new Highlander) will definitely incorporate mirrors AND a camera system.

Ok enough rambling. I sure hope those of you that hope to one day fly floats don't get discouraged by all this discussion about issues related to amphibs. Once you get your plane set up properly, and you get the proper training and get used to your new amphib, you will have an absolute blast being able to fly from land to water and back. It's like having your own magic carpet. I've always said that amphib floats is the best accessory you can add to an airplane. It in fact will make your airplane an amazing machine that will take you to places you probably otherwise would never experience. So don't let any of this discourage you. I can't imagine not being able to fly my Kitfox off water...it works so well.

Lynn knew going into this that turning a Jabiru powered Kitfox Speedster into an amphib might be a really challenging task. We had talked previously. And it certainly has been from all he describes. I'm almost embarassed how easy mine was to make work after reading of his struggles. But I have to say that it still looks like Lynn is going to pull off what many of us wouldn't believe was even possible with the Jabiru powerplant. So more power to him (no pun intended...really). I'm confident he is close to success, and will one day soon succeed in his mission. It might even be a bit selfish on my part, but I have this vision that one day soon I will see him land at the EAA Oshkosh Seaplane Base in his cool Kitfox amphib, and will have the time of his life in his new adventure machine

[DesertFox4]

I feel as though I could almost take my seaplane check ride after following this thread. Thanks for all the good reading guys. Something about float flying appeals to me like no other kind of aviation even though I have only some experience as a passenger and zero time on the controls of a web-footed aircraft.

Now , back to more float talk.

[av8rps]

A checkride?? That's funny!

I'm at least glad to know people are enjoying the thread while also learning from it.

I am a little concerned however that in trying to explain all this seaplane stuff in detail that it might appear a bit overwhelming to the average guy that is thinking about one day flying his or her Kitfox as an amphib. It's not really anywhere near as hard as this thread is making it appear. Not only does a Kitfox make for an excellent seaplane, but pretty much anyone can learn to fly an amphib well, and even though it may appear complex and overwhelming, if one learns properly and then practices it regularly, it will become second nature. And if one does it that way, it also can be done safely.

I think it is a lot like the latest trend of booney bashing with big tires and STOL aircraft flying around on sandbars and landing on tops of mountains (oh, and not to forget skimming water with your tires ). Doing that kind of flying certainly requires one to develop special skills, and an extreme ability to exercise good judgment and common sense, knowing what you and your airplane are realistically capable of.

But just like flying an amphib, when you get that all figured out just look at all the cool places you can go that the average guy with his 180 mph Spam Can can never go. I personally enjoy booney bashing almost as much as flying off water, as both require special skills that in my opinion not only makes flying more interesting and enjoyable, but the additional challenges also makes you a better pilot.

So we can beat this to death some more if there is further interest, or if people have additional questions. Otherwise I think we probably need to just let Lynn work on his floats so he can report back this spring after trying out his modifications.

Paul

[av8rps]

Lynn,

I know you are a very creative and talented guy. So I just want to plant a seed with you that might make the biggest difference ever with your Kitfox.

Think about the possibility of putting some sort of a prop reduction unit on that Jabiru so you can spin a longer, larger prop. I am absolutely convinced that if that were done to the Jabiru that it would truly be a kick-ass motor for a STOL type airplane like a Kitfox. Yeah, I know it would add weight, and it might require a bigger effort than it sounds. But I'm convinced it would produce so much more thrust that you wouldn't even notice the extra 10 or 20 lbs for a PSRU. And you'd be very happy with the extra effort to do it.

I say all that because of knowing how well my 80 hp 912ul with a gearbox reducing the prop speed works on my Kitfox IV amphib. I do cheat a bit by having an IFA IVO prop, but even if I use a fixed pitch prop setting it performs really well. As an example, the other day I was cruising around (on floats) at 105 mph at approximately 5000 rpm, which is only about 70% power with the prop setting I was using. While we probably can attribute most of that to the efficiency and performance of a 912 matched to a really good airframe, the reality is that turning a prop at a very efficient speed produces the most thrust for the available horsepower or torque. That in my opinion is where a 912 Rotax prevails over most other engines in its weight class. Turning a small and lightweight engine at high rpms so it can make the most horsepower and torque out of its size, coupled to a gear reduction that makes the propellor most efficient is why I believe the 912 does so well.

So with that said, now compare your Jabiru to the 912 ul. It is approximately the same weight as the 912ul (actually lighter), and produces about 4 hp more, with similar torque, but at much lower rpm. But then consider engine displacement. The 912ul is only 1,211 cc, or 74 cubic inches. By comparison the Jabiru is nearly 1,000 cc's more than the 912ul, with a displacement of 2,200 cc, or 134 cubic inches. So in a nutshell, the Jabiru actually has the same or more power than the 912ul (and probably way more potential for more due to more available displacement), but just doesn't apply that power to a prop as effectively or efficiently as the 912.

So imagine if you could add a prop speed reduction unit to the Jabiru that would allow it to turn a propellor at similar speeds to what the 912 does? I personally believe you would actually have as much or more power than the 912 ul.

To support my reason for feeling a PSRU would do so much for a Jabiru Kitfox, I will share a story most here probably don't know about our airplanes;

I remember Dean Wilson (designer of our airplanes for those that don't know) telling me about the first flights of the Avid Flyer prototype being a huge disappointment. It was powered with the most popular ultralight aircraft engine at the time, a Cuyuna 43 hp two stroke engine with a standard 50'ish inch ultralight prop bolted right to the crankshaft. Even though Deans calculations said 43 hp should be more than plenty HP for the very lightweight 364 lb Avid Flyer prototype, test flights returned poor at best performance numbers. Climb rate was only 200 fpm, and cruise only 55 mph. Frustrated, Dean almost scrapped the whole idea of the Avid Flyer. But after thinking about it more, even though the entire ultralight industry was using that engine and prop combination on most every ultralight, he came to the conclusion that turning that short prop at the rpm of that Cuyuna (about 6500 WOT) was making for a very inefficient propellor, resulting in very little thrust for the available horsepower.

So Dean went down to a local junkyard and bought the planetary drive out of a Ford C3 transmission. Then he machined a gearbox housing that held the ring gear and sun gears in place, and a adapter that would bolt all that to the crankshaft of the Cuyuna. Now he had himself a 43 hp Cuyuna that would spin a 6 ft diameter propellor with 36 inches of pitch at only 2200 rpm!

The test flight that followed the gearbox addition produced amazing results from the little 64 lb, 43 hp Cuyuna;

Instead of 200 fpm climb, he now had a 1,460 fpm climb rate!

And cruise jumped from 55 mph to 80 mph!

So every Avid Flyer kit was sold with a PSRU installed on the Cuyuna. And shortly after that (about the time Kitfox started), Rotax showed up on the light aircraft scene with their PSRU equipped 2 stroke aircraft engines. Of course we all know where that all went, with Rotax now being the number one aircraft engine manufacturer in the world (I often wonder if they ever gave Dean Wilson any credit for any of that, as they should have IMHO ...)

So, imagine discovering the true capabilities of the Jabiru engines by adding a gearbox that allows for a larger, more efficient prop, just like Dean Wilson did with the Cuyuna? I could be wrong, but I'm willing to bet you would see an amazing difference in your Jabiru Kitfox with the addition of a PSRU. And it would improve in all operational modes, climb and cruise, and land or sea, .

There you go Lynn...there's the seed I wanted to plant

[Dusty]

At risk of getting a little off topic,
I would agree the jabaru with a reduction would be a serious contender for one of the best power plants around.
Cooling would need to be improved(Rotec water cooled heads?)and a possible shift of the torque/power curve.
If the weight worked out ok, this would be worth considering for our type of aircraft.
Still some big boots to fill,the 912 will be top dog for a long time!

[av8rps]

Yeah, we probably should move this Jabiru PSRU to a thread of its own as there might be more interest in it where it is more obvious. But for now I guess we are still relating to float flying, so unless the moderators want to copy off this part and start a new thread, we can continue on here.

I'm somewhat aware of those liquid cooled heads from a friend that suffered at length with cooling problems with his early Jabiru 2200. But it seems that Lynn has figured a lot of cooling issues out with his Jab powered Kitfox, so I'm thinking it is possible his engine with a PSRU might actually run cooler?

Think about it, if it works like I think it might, he will immediately see more air through his cowl merely for the fact that the airplane is very likely to gain cruise speed with the same power setting. Plus, the bigger prop will probably push more air through the cowl too. I believe right now he is using his Jabiru engine to its max potential, just that the short prop isn't efficient on this airframe. So with a more efficient, longer prop he might not need to run it as hard as he does now. So again, that's why I think it could actually run cooler. I forgot to mention earlier that when Dean geared the Cuyuna on the first Avid, he saw lower temps from better cooling. Not sure all the reasons, or if the fan cooled Cuyuna would compare to the free air Jabiru that way? But maybe?

You bring up some very good points about doing this, and certainly all worth considering. But I don't think any of us will ever truly know until someone tries it.

I agree it would be a really big deal if a PSRU equipped Jabiru could even get close to what the 912 does, as the 912 is certainly the proven leader in applications like ours. But just imagine the response if it did better? Hey, maybe our Rotax prices might then finally come down

[HighWing]

I'm at least glad to know people are enjoying the thread while also learning from it.

Paul

I for another am enjoying it. I once flew in the factory float equipped Series 6 and that likely is it for me, but reading a very knowledgeable conversation between two of my favorite List contributors over the years brings back great memories along with a treasure trove of new knowledge.

Landing at Cameron Park after a "Splash and Dash" at Folsom Lake

ser6apro.jpg

One of these guys was my pilot, do you recognize the guy on the left?

johnjoe.jpg

[Lynn Matteson]

Paul, Lowell, Dusty and others-
Thanks for all the valuable insight and ideas regarding my float installation/training.
Paul, I just found the diagram that I drew after I had the floats rigged. I checked float top, lower door sill, and wing angles with a digital level. My drawing shows the floats at 2° up, the door sill at 6.2° up, and the wing at 8.1° up. Now on the wing, I checked the level figuring the center of the leading edge and the center of the trailing edge (I used a block at the rear to achieve a straight line reference through the "center" of the wing). So from what I'm seeing, I have 4.2° of incidence, right?....top of float to datum of aircraft. Then perhaps 1.9° more throat angle, for a total of 6.1°? I'm heading for the hangar right now to recheck the datum-to-wing angle. I will get reading this time using just the bottom of the wing and forget the "theoretical center of the wing" for now. I can't check the float-to-fuse angle as the floats are off. I'll try opening up the throat angle when I install the floats after repairs are made, but it seems as though as slow as it flies (with floats on), I gotta have more than enough incidence, eh?

Lynn

[Lynn Matteson]

Holy crap, Batman....I just put the digital level on the door sill and the bottom of the wing...the door sill read 11.8°, and the wing bottom (straightedge along the bottom surface of the wing) read 10.5!! I also re-measured the chord line angle (using the point on the leading edge that gives the chord its' maximum length) and this reading was 12.8°. Now I'm confused....if the bottom of the wing is compared to the door sill, the incidence is negative 1.3°, but if the chord line is compared to the door sill, the incidence is 1° positive. And from my previous post, I said that the float-top to door sill angle was 4.2°, and with hardly ANY "built-in" incidence, it doesn't sound like I have nearly enough throat angle....no wonder this thing won't get off the water!

Incidentally, I took a flight while I was at the hangar and it took 5 seconds to get airborn...not a worlds' record by any stretch, but seems like I have enough power to get the bird up without floats.

Lynn