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3W Bearcat with Moki 300

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3W Bearcat with Moki 300

Old 08-06-2023, 08:11 PM
  #426  
MCB458
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Hello Detlef,
Your Bearcat is amazing!!!! I am building the Rarebear version. Where can I buy the retracts (mains) that you have in your aircraft??
Old 08-06-2023, 08:56 PM
  #427  
Detlef Kunkel
 
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Originally Posted by MCB458
Hello Detlef,
Your Bearcat is amazing!!!! I am building the Rarebear version. Where can I buy the retracts (mains) that you have in your aircraft??

Sorry MCB,

we made 3 sets for 3 friends here, not more. The retracts are not commercially available
Old 08-07-2023, 02:44 AM
  #428  
mitchilito
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MCB, I hear that Century Jet has been sold to a new, enthusiastic owner. If you look early in this thread you will see that I, too, am building a rare bare version and used the old Century Jet gear. They were pure junk. Fortunately I have a machine shop so I rebuilt them from the inside out.

However, you might want to call the new guy and see if he will build you a new, higher quality set. I suggest you look earlier in this thread at my gear for a better understanding of what needs to be done.

Old 08-07-2023, 06:42 PM
  #429  
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Thank you Detlef.............. would you sell the engineering drawings? I have access to full cnc machine plus 5 axis capability.
Old 08-07-2023, 06:47 PM
  #430  
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Mitchilito, Thank you for the information! Your Bearcat is awesome also! I have Sierra Giant scale gear now.....it will work for what I want to achieve.....just won't have the cool factor of the original.
Old 08-07-2023, 06:50 PM
  #431  
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For the elevator and rudder hinges, what are you guys using? The Bearcat has a tendency to develop elevator flutter at high speeds if all is not rock solid.
Old 08-08-2023, 02:38 AM
  #432  
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Originally Posted by MCB458
For the elevator and rudder hinges, what are you guys using? The Bearcat has a tendency to develop elevator flutter at high speeds if all is not rock solid.
I used used Savox 1270 servos, big Robert hinges, and titanium rods. I also balanced my ailerons. There will be no flutter.

Speaking of flutter, be very sure that you look at the wing control surface supports. They are a very expensive disaster waiting to happen. You'll see how I approached this in my build pics in this thread. Detlef removed and replaced his with sturdier ones.
Old 08-08-2023, 02:44 AM
  #433  
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Originally Posted by MCB458
Thank you Detlef.............. would you sell the engineering drawings? I have access to full cnc machine plus 5 axis capability.
You'll have to get him to sell you the drawings for the new wings (required) as well
Old 08-08-2023, 10:34 PM
  #434  
Detlef Kunkel
 
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Originally Posted by mitchilito
You'll have to get him to sell you the drawings for the new wings (required) as well
correct Mitch.

You COULD rebuild the original wing to accept the scale gear, but it means nearly destroying it by 50% and then mend it. Makes little sense.
Old 08-08-2023, 10:44 PM
  #435  
Detlef Kunkel
 
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Originally Posted by MCB458
The Bearcat has a tendency to develop elevator flutter at high speeds if all is not rock solid.
absolutely true!

here my solution, I hope the pics are self explaining:

Important before you cut open the front of the elevator, make a thin form shell so you have an easy chance to close it later


PS sorry for the distorted pics. No idea why this happens. Seems to occur only when the pics are turned by 90
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Last edited by Detlef Kunkel; 08-08-2023 at 10:46 PM.
Old 08-08-2023, 11:43 PM
  #436  
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Originally Posted by MCB458
I have access to full cnc machine plus 5 axis capability.

MCB,
Why didnt you say that earlier?

we would have been a dream team :-)



To be honest:

You may know that we were 2-3 People for this project, and reall spent a LOT of time & money to come so far.


I cannot imagine that someone can and will pay a realistic price for the full set of CAD construction / design documents so both parties are pleased.

I had requests like this before, but my chaps here are semi- interested.

Hope you understand this
Old 08-09-2023, 03:55 AM
  #437  
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Almost done with my "quick engine change package" (that's what we used to call this in the AirForce :-).

I'm using an ElecroDymaics 5-lead "one-click" connector to connect ALL the electronic bits. I love these connectors. Also have two Festo quick disconnects for the fuel lines. So to remove the entire engine package I just disconnect these three things, remove the eight motor mounts bolts and she's free to work on.



My "one-click" connector. Been using them for YEARS. Love them.

Testing the fuel system in this pic.

I'll be using an Aura-8 flight stabilizer on this machine. They are an AMAZING device. Here's my setup if anyone is interested.



Old 08-09-2023, 06:04 AM
  #438  
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Mitchilito,

Thank you for the info! You are right about wing hinges......I will definitely redesign the aileron hinges.

My Rarebear will have fixed flaps just like real one.



Old 08-09-2023, 06:07 AM
  #439  
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Detlef,

I completely understand about the retracts. You guys did an amazing job!!

Also, your elevator hinge system is VERY creative and will be bulletproof....:-)
Old 08-09-2023, 07:08 AM
  #440  
Detlef Kunkel
 
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Just a test about the pics



The carbon shaft is square, not just rectangular

Inside the elevator rudder, there is a square sleeve. The unit is placed in the rudder with 2 layers of carbon fibre.
It is a solution definetly made for withstanding any flutter tendencies ( proved before in other pretty fast planes including flutter friendly 65 pound heavy P_47)
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Last edited by Detlef Kunkel; 08-09-2023 at 07:11 AM.
Old 08-09-2023, 07:34 AM
  #441  
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That thing definitely looks bullet-proof Detlef! Also seems pretty light for its strength.
Old 08-09-2023, 09:33 PM
  #442  
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Mitch,

when I see your setup with all components around the intake of the engine, we had that point before.

The engine will normally "sweat" a little fog of gas and -of course - oil fog over the time.

I personally would NEVER run such an expensive engine without air filter.

I use K&N 62-1370 on all my engines, stack length is not critical on the Moki, depends (can be adapted) on situation.

Whatever the engine sucks in, it is affecting a lot of needle bearings, pistons, conrod bearings etc.


Second effect: the "oil & gas breathe" behind the engine is 99% caught in the filter, keeping the filter slightly lubricated as K&N recommends it.

I am sure you can manage a longer stack and a filter position outside of the ignition level without too much trouble


Pics show a few examples
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Old 08-10-2023, 02:35 AM
  #443  
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Great advice, Detlef. I do have an air filter for it, just hadn't decided to use it or not. but you are certainly right about the "expense to damage" ratio on this engine!

And thank a BUNCH for the equipment install pics. I'm pretty sure I'll get some good ideas from these!
Old 08-10-2023, 09:15 AM
  #444  
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Well, the air filter I had wouldn't fit so I decided to manufacture one! I found some foam that had the perfect density and a piece of thin wall aluminum tubing (began life as a helicopter tail boom :-) and I made the cover out of Delrin. See pics for explanations.



I cut the flange off the stock velocity stack - tube now fits perfectly. Machined little cover out of Delrin.

Has the capacity to flow a LOT of intake air.

Body installed and safety wired. Hole in cover is for the retainer plate.

Slip the foam element in place and. . . . . .

. . . screw on cover plate. Ready to roll.
Old 08-10-2023, 11:31 AM
  #445  
Detlef Kunkel
 
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Mitch,

foam filter for this engine?


Do a test with and without, in an y case with proper H-needle setting, and see if the engine loses power.


I personally dont like the idea too much. ( that doesnt meain it doesnt / cannot work!).

But I had a tough school during my racing years, causing some preferences settled firmly..



The surface of a professional filter ist so much higher than what you can suck through the few holes and the foam area behind.


From the " debries sucked in " point of view surely better that without.


Go try. :-)
Old 08-11-2023, 01:53 AM
  #446  
mitchilito
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Originally Posted by Detlef Kunkel
Mitch,

foam filter for this engine?


Do a test with and without, in an y case with proper H-needle setting, and see if the engine loses power.


I personally dont like the idea too much. ( that doesnt meain it doesnt / cannot work!).

But I had a tough school during my racing years, causing some preferences settled firmly..



The surface of a professional filter ist so much higher than what you can suck through the few holes and the foam area behind.


From the " debries sucked in " point of view surely better that without.


Go try. :-)
I always appreciate your unvarnished opinions, Detlef :-)

I'll say this: in it's dry dry, un-oiled state this filter flows PLENTY of air. However, when it gets saturated with oil mist as you discussed I can see how it may begin to restrict flow somewhat. But I will say this about that: I'm honestly not concerned with squeezing every molecule of performance out of this engine. This aircraft is so preposterously overpowered I think I could sacrifice a horsepower or two . However, I will try a "without" test once it gets saturated to see what it does as you suggest. As you said, debris protection is the main idea here.

You know, in the past, when I was a young stud-muffin, I would NEVER have given up a single horsepower. Hmmm, how times change. . . .
Old 08-11-2023, 05:29 AM
  #447  
Detlef Kunkel
 
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Red face

I dont mind the try.

Go ahead Mitch. There is always more than one way..


And what you say about the power....completely true
Old 08-12-2023, 02:27 AM
  #448  
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I've spent the last couple days trying to setup a THROTTLE TO FUEL PUMP mix on my Spektrum DX18 transmitter. I ASSUMED it would be easy/peasy but NO. All it has to do is mirror the throttle - but with lower end limits and yet nothing I do can achieve that result!

Does anyone out there know how to do this??

Old 08-12-2023, 10:12 AM
  #449  
Detlef Kunkel
 
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Originally Posted by mitchilito
I've spent the last couple days trying to setup a THROTTLE TO FUEL PUMP mix on my Spektrum DX18 transmitter. I ASSUMED it would be easy/peasy but NO. All it has to do is mirror the throttle - but with lower end limits and yet nothing I do can achieve that result!

Does anyone out there know how to do this??


Sorry I have not the slightest Idea about Spektrum. It should be a 40-60% mixer with an offset ( to zero) function when you switch the pump off.


The principle itself that I described to you is clear, you only find no way on your spektrum TX?
Old 08-12-2023, 10:34 AM
  #450  
Detlef Kunkel
 
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Maybe this will brighten up your cloudy mood about the mixer :-)

The following 2 users liked this post by Detlef Kunkel:
MCB458 (08-12-2023), mitchilito (08-13-2023)

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