Building a Javron Cub

Bill Rusk said:

Glenn - don't know yet. Would like to. Depends on how it all comes together.

Pete - I am thinking of a removable handle with a quick convenient storage and quick disconnect, or possibly a telescoping handle.

Still working on the details.

Bill

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Bill,

I would never, ever consider a (regularly) removable handle for that float pump. One slip in a little turbulence, or a moment's distraction, and that handle will wind up back aft somewhere, or under your seat......resulting in contortions and cursing as you try to retrieve it. This falls into the category of "What could possibly go wrong?" in my opinion. I'd just mount that pump wherever it fits and works best. On the floor under your right leg always worked for me for ski pumps.

MTV

Great inputs gents. Thank you..

Mike - Still thinking and working out the details, but you make a valid point which I will consider. I can now tell you all, with great authority, there is not a lot of extra room in a Cub to put a manual float pump. It all has to come together just right to make it work and be safe. It is one thing to mount a back up manual pump that will only be used once, and only in an emergency, and it is another thing entirely to set it up for regular use. I think it is going to work but it is not a just a quick, "oh, yea, we will stick it here" process.



Rudder bar



Start of retract pulley fabrication. I left room in front of the pulley to insert a cotter pin to keep the cable on the pulley. This cable can, and will, go slack so it seems important to make sure the cable can not slide off the pulley.



Just a neat photo by my good friend Buck. The elevator is touching my hangar.

Hope this helps

Bill

Bill,

believe me, I know what you mean. I've flown a few Cubs with ski pumps, and one that had a 32 gallon belly tank with a strictly manual pump to move all those gallons up to the wing. You're right...there is no ideal spot for a pump in a Cub, but once installed, you'll adapt to it pretty fast.

And you're right....you don't want the retract cable to jump off its pulley....

MTV

Bill Rusk said:

Start of retract pulley fabrication. I left room in front of the pulley to insert a cotter pin to keep the cable on the pulley.

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Bill, You might trim that lower aft edge back 1/4" or so to prevent the cable from dragging and chafing strands.
ps. It could also be bent down with a radius to act as a ramp for the cable to ride on.

What do you have behind the fabric to prevent the pulley assembly from bending aft under load? What is it attached to? The initial pull on the water rudders has the highest load.

Pete and Mike

Thanks for checking up on me. The pulley is (or will be) bolted into this plate that I welded in.



See this post in my thread
http://www.supercub.org/forum/showt...g-a-Javron-Cub&p=575496&viewfull=1#post575496

Bill

Folks

Still chipping away at the float install. As usual I'm kinda slow, but making progress.


Needed a hook for the rudder retract cable. Got a 3/16 X 1 1/2" eyebolt from Home Depot aircraft parts store. Then took a Dremel tool with a cutoff wheel and opened it up. Rounded off the end with a file so it looks like........



I also put one on the side wall so the handle does not flop around on the floor. The panel location is due to there being a welded metal tab back there so when the handle is up (and heavy) the hook is strong and well supported. The sidewall hook is just in the thin sheet aluminum but it has no load/weight in that "down" position so the hook does not need a lot of strength.



Also did the weight and balance. I'm fortunate to have access to a 4 scale set up so that made things easier. Both mains came in at 501 and the nose at 163 and 172 for a total of 1337. According to my calculations that puts me at 71.9 on the CG (11.9 if using the LE as the datum, I'm using the prop face thus + 60). Figuring a worst case forward CG scenario, me = solo, and I've run the airplane out of fuel and have 8 Qts of oil (I don't run 8 qts but that is worse case), that puts the weight at 1337 +180 = 1517
If we look at the CG graph in the TCDS the left side is a sliding value based on weight. At 1517 my best (conservative) guess is the forward limit would be right about 72.5. I know from running lots of numbers that the CG moves aft 1" for every 10 pounds of lead in the tail (in the place I set up to add weight). So......10 pounds of lead in the tail should bring my CG to 72.9. Everything from there will move the CG aft, ie fuel, passenger, tool kit, camping gear or survival gear, etc.
If just messing around locally I may choose to add more lead to move the CG further aft just to improve flight characteristics. But I can remove all lead and substitute camping gear as appropriate. So, I'm pretty happy with these numbers. I'm hopeful that it will perform well. If I put a 5' level across the top of the floats at the rigging area (the tops have a bit of slope so finding the "level" part is not exact) and zero the level then place it on the bottom of the wing I get 5.9 degrees. So......from the floats to the wing I have 5.9 degrees incidence. This was attained using standard SC rigging from Wip. I made no changes to the rigging, so I assume (uh oh there is that word) that this is a standard value, give or take a little, from Wip. From reading, and talking to others, this seems like a good number. It may take a little off the cruise speed but should offer excellent "out of the hole" take off performance. We will see.

Hope this helps

Bill

Bill Rusk said:

.... If I put a 5' level across the top of the floats at the rigging area (the tops have a bit of slope so finding the "level" part is not exact) and zero the level then place it on the bottom of the wing I get 5.9 degrees. So......from the floats to the wing I have 5.9 degrees incidence. This was attained using standard SC rigging from Wip. I made no changes to the rigging, so I assume (uh oh there is that word) that this is a standard value, give or take a little, from Wip. From reading, and talking to others, this seems like a good number. It may take a little off the cruise speed but should offer excellent "out of the hole" take off performance. We will see.l

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Progress, I set the incidence angle on mine at 3.5 degrees and am very pleased. I await your speed and stability report. Until then, mums the word.

Well........egg on face.....and boy do I feel dumb. A friend flew his Hatz biplane in to visit today (enroute to the Maac fly-in this weekend at Brodhead). So he was looking at the Cub and the floats, and he asks....."whats this"? Oh that is a float locker, you can store stuff in it and I open it up and ......Yup.....it is full of stuff I forgot about. (ropes and bumpers) So....subtract 7 pounds off the W&B. I wondered why the right float was heavier than the left. Well duhhhh!!

Oh... but it gets even better. Then he asks "Whats this"? That's a float pump. You use it to pump out any water that might have gotten in the floats. It works like this..........Yes Ethyl....water comes out. Really? REALLY? These floats have been in my hangar a couple of years. Been stripped and repainted. I honestly just never thought there could be water in there. After a couple of pumps I decided to get a bucket and weigh the pumped out water. 5 Pounds.

Just in case there is someone out there that thinks I have a clue, I'd like to dispel that notion right now. Holy buckets. Lets do an accurate W&B, but perhaps you should clean out the floats and pump them out first. Geeez.......

So the new empty weight on floats is 1337 - 12 = 1325

Embarrassingly yours,
Bill

It's almost like pierce was around. He is good at hiding lead in your airplane when it's on scales. I will say, he didn't leave his cub alone when he had it on scales. . .

No worries Bill, none of us would ever mention it.

Bill Rusk said:

Well........egg on face.....and boy do I feel dumb. A friend flew his Hatz biplane in to visit today (enroute to the Maac fly-in this weekend at Brodhead). So he was looking at the Cub and the floats, and he asks....."whats this"? Oh that is a float locker, you can store stuff in it and I open it up and ......Yup.....it is full of stuff I forgot about. (ropes and bumpers) So....subtract 7 pounds off the W&B. I wondered why the right float was heavier than the left. Well duhhhh!!

Oh... but it gets even better. Then he asks "Whats this"? That's a float pump. You use it to pump out any water that might have gotten in the floats. It works like this..........Yes Ethyl....water comes out. Really? REALLY? These floats have been in my hangar a couple of years. Been stripped and repainted. I honestly just never thought there could be water in there. After a couple of pumps I decided to get a bucket and weigh the pumped out water. 5 Pounds.

Just in case there is someone out there that thinks I have a clue, I'd like to dispel that notion right now. Holy buckets. Lets do an accurate W&B, but perhaps you should clean out the floats and pump them out first. Geeez.......

So the new empty weight on floats is 1337 - 12 = 1325

Embarrassingly yours,
Bill

Click to expand...

Sounds like a good reason for celebration! You worked so hard to save an ounce here and there through trial, research and great expense. Now with a few quick actions saved 12 lbs.

Bill,

You can probably get another five pounds of water out of those floats by removing the hatch covers and sponging out the residual water....... Granted, that's water that will live in those floats during regular use anyway, but it's perfectly legal to weigh your plane with NO water in the bilges and thus lower your empty weight.....

But, in any case, I hope you opened every float compartment hatch and verified the integrity and length of the pump out tubes? I've seen these things not well attached, split or broken at the bottom, shorter than they could have been, the ends not located in the lowest point of the compartment, etc, etc, ad nauseum. If you haven't specifically LOOKED at every one of the pump out tubes, I'd sure do so before you go operational on floats. Easy to do sitting in your hangar, and you may find another few pounds of water that you need not be lugging around the rest of the summer.

Finally, that residual water in the floats should be a clue as to winter storage of your floats. If you plan to store them outdoors, get every bit of water out of them that you can, then add some RV anti freeze to each compartment to prevent seams from freezing. Probably not really necessary, but it can't hurt.

MTV

Bill,
Looks like you have the old style pump out plugs also. I'd get the new style to help keep water out when splashing about on the lakes. Notice your's sit below the top of the float, and the rope acts like a wick with a hole straight into the compartment. The new one are domed up and the rope does not go thru the plug. Also check that the compartment gaskets are in good shape. I can leave mine sitting on the lake for days and get almost no water out. Go do 10 landings and pump 1/2g from some of the front compartments. New plugs helped fix the problem.
Nice looking plane.

Mike and Todd

Thank you for those good and helpful posts



The new pump came in. Thanks MMR for your help. On the left is the Parker 914 series pump. It takes 25/22 strokes to raise and extend the gear. On the right is the new Parker 910 series. It takes 13/15 strokes to raise and extend the gear. It is about 18 ounces heavier than the 914 series and a little fatter. They make three models of the 910 pump. The only difference is the fitting ports. I got the 910-6D2BC model


Another angle. Notice also the handle and how it fits. The 914 handle slides into a tube. In the 910 series the handle goes over an extended stub.



This is how the pump is mounted to the seat post and also how the valve bolts right into the pump (with the right fittings of course). The 914 series pump will require a Fragola 495110-BL and a 495111-BL. The 910 Pump uses 2 of the Fragola 495110-BL fittings. This gives you a male AN-4 fitting out. I drilled and re-tapped one of the fittings for the bottom for an AN-3 pipe to male fitting so it took less space. You will also need a 499304. This is a 1/8NPT to a -4 female. This connects the male out of the pump to the 1/8NPT in the valve.



This is the bottom of the pump where I tapped into the O ring 495110 fitting to put a std AN fitting in to keep it smaller, for clearance issues. You will want to mount the pump as low as possible.



This photo shows the longer handle stub. You can see the step where the normal handle slides down over and rests at the step. The handle supplied with the pump is a steel tube, that I swear weighs 10 pounds and is 2 feet long (with a bicycle grip). I will make a shorter handle out of aluminum tube.



This is the pump in the airplane (w/o the valve, which would be on the left as you are looking at it). You will note that I had to cut the handle at the step for clearance. As it is now the stick does not hit or interfere with the pump in any possible way (picture is with FULL right aileron). It is also clear of your legs and feet. You really can't tell it is there. But as noted earlier, I will have to make a removable handle, that will slip over the stub that is left in order to get adequate leverage.



In this configuration there is no interference with the back seater's rudder pedals, feet, etc and no issues for the front seater as well.



What it looks like in the airplane with all the plumbing hooked up. I will refine the plumbing lines in the future. I just wanted to get things hooked up so I could test it out.



Photo is a little deceptive. The rudder pedal is full forward and there is about 3/4 to 1 inch of clearance. That includes shoes, stop to stop, and all that.





Hope this gives you some ideas, and that it helps someone out there, even if you decide you don't want to do it this way. This will work for me, but it might not be right for you.

Bill

PS



I took your suggestion and angled the aft end of the pulley housing for more clearance.

Hi Bill,
Congrats on a fabulous build and you are missed when you are not posting.
I was wondering if you have a p/n or supplier for the tie down bolt in the above photo between the leaf springs and the tailwheel assy. It's another nice touch. Also do you know who supplies the throttle balls with the integrated PTT switch ?
Many Thanks
Peter

Thanks Peter. The tail hook eyebolt comes from Air Repair. It is from the L19. Their # is 662-846-0228

The PTT switches were picked up at an electronics store in a large bin. Unfortunately there is no # or any identifying information on them at all. The store is about a 1.5 hour drive from where I live. The next time I'm over there I will see if they have any more and get a handful. They were only about a buck each. If I can get some more I will send them your way. They work great. Wish I could be more helpful on that but I can't find ANY info on the switches.

Bill

Thanks very much Bill

Bill, did you use nut plates in all the channel, holding the boot cowl, sky lights, windshield, etc?

Thanks
Tom

Did you attach a dip stick to the filler cap?

ps. Bill, Notice the two holes in the tube. The one near the end is the minimum level. The other one is the full mark. Keep in mind that, depending on gear up or down position, the full level will be different and that if you do not allow for air space above the full mark you will get an overflow all over the inside of your nice plane.

There is a vent on the reservoir or cap isn't there?

pps. The distance between the two holes is the difference between the levels with the gear up or down.

Tom - Yes. I nutplated EVERYTHING.

Pete - neat idea, I like it. Will consider. The downside to the aluminum reservoirs (frequently) is the inability to see the quantity level with a quick glance. Some have a sight tube similar to the SC fuel gauges. The clear reservoirs are obviously better in that respect.

Bill

looks an awful lot like an Atlee tank for ski pumps...

When will they be on the market? I hope to see some on other's aircraft!

An outboard oil injection tank might have been a solution, but it is nice to have metal surrounding fluids, plastic tank hose connections break easily.

Folks

More info.....



I was talking to my friend Lytel about all this manual pump stuff (he is way smarter than I am) and he asked why I did not take the outflow line and "T" it into the input line, thus getting rid of a return line to the reservoir. Basically the input line now pulls from the return line, or the reservoir, or both to get its feed. If there is excess fluid it just goes back to the reservoir. Before we had two lines - each was a one way street. Now we have one line - and it is effectively a two way street. So what you see is..... on the left side of the valve you see a aluminum line coming out and down and "T"ing into the bottom opening (input port) of the pump. The other side of that "T" goes to the reservoir. Before - I had this line going to the reservoir.
In a nutshell this eliminates a line. Less complicated is better, lighter, fewer failure points etc.
This seems to work fine, in fact even better than before. I'm not sure why, but it now takes fewer strokes to raise and lower the gear, and it seems to have evened things out, usually taking about 13 strokes to retract where you are fighting gravity and the handle force is a little higher, and 15 strokes to extend where you are going with gravity and the handle force is very light. The stroke count varies a little depending on where the handle starts from, and how you count partial strokes, but a good ball park figure is around 13 retract and 15 strokes extend pretty consistently.
Now we have just one line to the bottom of the reservoir. The other input port on the reservoir is just plugged off.



I put a bend in the handle to make it more comfortable to use.



What it looks like in the airplane. Back looking forward.



Next season I will refine the hydraulic lines. Right now they are a little long. Next year I will have new lines made up with an exact fit. This season (what is left of it) is really just a test season and to get the bugs worked out.

This is a short video of how it works. If the weather cooperates - first flight on floats tomorrow.

Hope this helps

Bill

Bill, i will be going through the same process next year with the glasair sportsman i am building and REALLY appreciate you breaking the trail for me and the others who may be going through a similar process. thx and thx again
Marc

Maybe I'm over thinking the removable handle issue, but I'd sure want a tether or some other means of keeping the handle close to the pump. Too often, I've had to reach for something in flight that I thought was close (flashlight, calculator, plotter) and found that it had migrated to the position of being "just out of reach". I've seen the results of a few amphib water landings on extended gear. It'd be a shame to not be able to retract (or extend) the gear when needed.

Mike (and Mike V)

I agree. I have not yet figured out exactly how I am going to handle the pump handle issue. Sometimes when I need to think about problems I need to handle I listen to Handel's Messiah, Water Works, or perhaps Music for the Royal Fireworks.

Seriously all Puns aside - I appreciate the input and I am taking that issue seriously, and I will come up with a safe way to handle the handle.

Bill

Ursa Major said:

Maybe I'm over thinking the removable handle issue, but I'd sure want a tether or some other means of keeping the handle close to the pump. Too often, I've had to reach for something in flight that I thought was close (flashlight, calculator, plotter) and found that it had migrated to the position of being "just out of reach". I've seen the results of a few amphib water landings on extended gear. It'd be a shame to not be able to retract (or extend) the gear when needed.

View attachment 21800

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Put a bungee in it like a tent pole and some Velcro on the handle and store it velcroed under front seat

Glenn

Bill, i dont know anything about floats or handles, but i like my little storage area in the butt rib leading edge compartment in the wing, where the leading edge D formers are welded to the fuselage. Then you would be reaching up instead of down. Maybe make some kind of a bracket so it wont slide into the wing? Might have to straighten the handle out a little.

Or a clip like this to your overhead cross bars thats out of the way? http://www.ebay.co.uk/bhp/tool-clips

I would do like Tempdoug said but put it on the right panel in front of the door