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Building a Javron Cub

Folks

Back to work tomorrow and I will have time to think about the handle issue. I can say .....now......she flies great on floats!!!










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All the systems worked absolutely great. There is only about a 1 or 2 MPH penalty for having the gear down Vs up, so again there is no rush to retract the gear right after TO, and you can extend it well before getting in the traffic pattern so you can focus on looking out for traffic. At 2400 RPM I am getting right at 100 MPH almost exactly what I was getting on the 31" Bushwheels. I was VERY pleased with the stability on the vertical axis (yaw) so at this point I will not be adding a ventral fin. Stalls that I have done so far are a non event, as was ground handling. Much more testing to follow.



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Javron Cub on the water.



Bill
 
Some nice work going in to this plane. I can not wait to see it.

couple of thoughts, at some point just bolt the handle into the pump and be done with it. Make a handle with weird curves to get it out of the way in flight, and off you go. No need to remove and stow.

The selector valve looks to be in a great place and out of the way. I do worry about it hanging out there with only the fitting and lines to support it though, and the line going down looks like a great thing to be broken in flight when you set a camera or something, (454 Cassull) on the floor for a long flight and hit some bumps.

consider doing a 90 right out of the pump and laying the selector against the body of the pump, which would allow a much shorter line going down way out in space. Then a simple strap around the pump housing would support the valve.

If you want to bring that bird up and show it off, there is a lake just up the road from me for you to land.

Will you be painting it blue this winter in preparation to your new office?:p
 
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.

Best thing I did was un cover these.

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Also do you know who supplies the throttle balls with the integrated PTT switch ?

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.

I had a hunch that I knew which electronics store Bill was talking about, and I think I guessed right. Traffic was awful on the way home from work, so I took a quick detour and picked up a few.

If anyone wants a switch (or two), send me a PM with your address and I'll drop it in the mail. I have red and green, and could pick up yellow if there's interest.

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Mike

You are the best. Thank you for doing that and for that offer to others. Very nice.

What a great community we have here!! If you get out my way we can jump in the Cub.

Best regards

Bill
 
Thanks for all the inputs gents. Still don't have a good plan for the stick yet but I'm sure having fun "testing" things out. The gear system works great. Simple, light, easy......I LIKE it. It is just as I imagined and hoped for. Still need to work on the idle some more. Better but not perfect just yet.



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I am not very familiar with TO times but it is off the water in normal fashion in about 10 seconds and if I yank it off (popping flaps)I can get it off in about 8 seconds right now. Not sure if I can improve on that much. If I yank in much less than 8 seconds I drag the tails and it hurts more than helps.


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Remember that cool little trick I showed you for putting a door "key" allen wrench on your ignition key? Well if you put the water rudder cable right below it, it gets in the way. Furthermore the key needs a float on it but that will also get in the way. So.....don't put your ignition switch right above your rudder retract handle.


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Good picture of my friend Mike, with the Beaver he got to fly some this summer. I'm jealous!! Beautiful plane.


Hope this helps

Bill
 
...I am not very familiar with TO times but it is off the water in normal fashion in about 10 seconds and if I yank it off (popping flaps)I can get it off in about 8 seconds right now. Not sure if I can improve on that much. If I yank in much less than 8 seconds I drag the tails and it hurts more than helps.
Bill, What is your CG during those take offs? How many degrees of flaps do you use before yanking? I use 36 degrees. 56 degrees will lower the time by about 1 second. Try using a little more nose up trim. Instead of yanking flaps try raising the right float a little without changing pitch.
 
Jr - Yes he does. To top it off he was going to a really beautiful lodge up in BC. Stunningly beautiful area.

Pete - What was my CG? Well......in looking at the chart on the TCDS we get to have some fun.
Less than 1400 pds = 71.1 (I'm using the prop face as the datum so Piper numbers + 60 inches)
at 1500 pds the forward limit looks to be about 72.4
at 1600 pds the forward limit looks to be about 74.0
at 1700 pds the forward limit looks to be about 75.0
at 1800 pds the forward limit looks to be about 76.0 (Chart ends as the max gross is 1760)
Then if we continue to interpolate the chart it would seem that we are moving the limit aft about 1" per 100 pounds thus at 2200 pounds the forward limit is 80 and the aft limit is 80 and if we load the acft past 2200 pounds the lines have crossed and the forward limit is now behind the aft limit. Interesting little problem.
My test flights started at 1325 for the acft. After adding fuel (used a mid range number of 150 pds), oil, pilot (190 w/clothes, headset, vest), and 20 pounds of lead in the tail we get 1692 weight and a CG at 75.26 (forward limit at this weight = 75)
10 pounds of lead (in my ballast point 233.6") moves the CG aft exactly 1 inch, so I could add another 20 pounds of lead to move the CG to 77.2 which would be closer to midrange. I have not done that test yet. I will fly the plane tomorrow with a GW at 1900 and right at the aft limit of 80". We will see how she performs.
I put the smart level on the bottom of the wing and zeroed it out. My first notch of flaps gives me 22 degrees (relative to the bottom of the wing) the second notch is 36 and the last notch is 46 degrees. I have not tried a TO at other than the first notch, thus I was popping the flaps from 22 degrees to something close to 46 degrees. I will try some TO's with two and three notches of flaps.
I tried rolling it up on the left float and it did not seem to help. 8 seconds still seems to be my limit. Also note that I could go to a lower pitch prop which would help as I am currently only getting about 2300 RPM at the onset of the TO. My understanding is that 2500RPM would be a better number but of course I would then loose cruise speed. I'm happy at 8 seconds. Less than that is just for competition or gee whiz wow factor.


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Thanks for your interest, Pete (and others)

Bill
 
Bill,

See if you can get a copy of the amphibious Top Cub CG graph. That airplane is approved at 2300 lbs, and as I recall, the graph is reasonable on Wip 2100 floats. Since that plane is for all intents identical to yours, seems to me it'd be a great place to start. After all, CC has already done the testing for you.......

i was amazed that you could actually load that thing and keep it within CG limits--the Top Cub, that is.

Mtv
 
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MTV

Excellent idea Mike. The CG chart for a regular Cub really doesn't work, as described above, at the higher gross weights we are using now. Flew yesterday at 80 inches (aft limit) and about 1900 pounds and it flew great. No noticeable handling issues at all, and it came off the water in about 10 to 12 seconds, obviously a little slower from the increased weight. Thanks for the input. I'm hoping, before the season ends, to find a way to get out East and perhaps fly with Pete (if he will put up with me) for an afternoon. Sooooo much experience there I'd like to tap. And I'll see you in the Spring on my way to Alaska.

Bill
 
Bill,

Mike's idea of the CC chart is a good one to expand upon for your application. I tested to an aft CG of 20.25" (80.25") and 2000 lbs. That is where the spin tests were done and there was no indication that the limit could not be set even further aft. Normally I fly with full fuel at about 1900 lbs and 17.5" (77.5"). Generally the TO times are less than 10 seconds. I suspect that is because my flaps are longer than yours. They go out to the strut attach location on the wing. Do you have a manifold pressure which you use at cruise? ??mp at 2400 rpm? Mine will do about 108-110 mph at 21.5"/2400 rpm.
 
Pete

Thank you, good info. I do have a MP gauge but it is currently disconnected, one of those little jobs I need to get to. I am getting 100MPH at 2400 RPM, but I don't know what MP that is drawing. That Whirlwind prop you use seems like it is pulling really well for you to have those TO times combined with that cruise speed.
When I flew yesterday at about 1900GW and 80" CG the airplane flew fine and I did not notice any adverse handling issues. I had plenty of trim left at both airspeed extremes.
I will try to find a Top Cub GC chart.

Bill
 
The Whirlwind does pull well. That speed and time are at an intermediate blade angle setting. I need to figure out how to make it controllable without installing a governor. There is tubing in the way behind the firewall. Another 3 or 400 rpm on take off will lower the TO times to about 6 or 7 seconds and 24"/2400 rpm will give close to 120 mph cruise.
 
Pete

Thank you, good info. I do have a MP gauge but it is currently disconnected, one of those little jobs I need to get to. I am getting 100MPH at 2400 RPM, but I don't know what MP that is drawing. That Whirlwind prop you use seems like it is pulling really well for you to have those TO times combined with that cruise speed.
When I flew yesterday at about 1900GW and 80" CG the airplane flew fine and I did not notice any adverse handling issues. I had plenty of trim left at both airspeed extremes.
I will try to find a Top Cub GC chart.

Bill

Bill,

You might start a thread on this forum, asking if anyone has a CC 18 (note that there are Super Cubs out there which CC called "Top Cubs as well, but they're 2000 lb) on amphibious floats who would be willing to copy the W/B graph for you. Or, you might try CC......

MTV
 
Bill,

You might start a thread on this forum, asking if anyone has a CC 18 (note that there are Super Cubs out there which CC called "Top Cubs as well, but they're 2000 lb) on amphibious floats who would be willing to copy the W/B graph for you. Or, you might try CC......

MTV
It is all here on page 2.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e2e611828ee3bf3586257ced0045b29c/$FILE/A00006SE_Rev_7.pdf
 
Bill:

What is the part number of the two diodes you used in your electric trim wiring? (Building a Javron Cub, page 28)

Louis G. Bourgois III
Lexington, Kentucky
 
Louis

I just went to the local Radio Shack. There are probably better out there and perhaps one of the electrical guru types like Fobjob, Wireweenie, etc will chime in and give us better info, but this has been working just fine for me so far. I used #276-1661
It is a four pack of 6 amp, 100V (the motor can only draw about 1.1 amps even when stalled out) diodes. You could also use 276-1114 a three pack of 2.5amp 100V

Hope this helps



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Mom came to visit and got her first floatplane ride. She thought it was pretty cool.


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Sis got her first floatplane ride as well. She loved it. Might do a stint with me next year in Alaska. Brave soul. LOL



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One happy camper!!

Bill
 
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Good on ya, Bill! Great photos, and a floatplane being used for what they're best at...having fun.

Anyone who needs electronic parts would do well to contact Digi Key in Thief River Falls, MN. They are a HUGE distributor of electronic components. I called them looking for a three way switch once, and wound up talking to a very knowledgeable person there. I explained what I wanted the thing to do, and they sent me precisely what I needed.....took maybe fifteen minutes on the phone, and the switch cost $3.00. And, it's been used heavily now for a long time.

Great outfit, and owned by a guy who owns and operates his parent's bakery. Great story. He built up the electronics business as a teen in his parent's basement. He worked in the bakery his folks owned....then took it over. Digi Key is HUGE, but he still works in the bakery, last I heard.

MTV
 
Bill, Congrats on that last pic. I know what it has taken on the soul to finally get to land in the middle of a lake in a bird that you assembled yourself(not to discredit all the help along the way) It was a true smile of accomplishment. I just dropped off my fuselage to Javron Monday night and I look forward to the journey. Blue Skies, Denny
 
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