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??

Detlef Kunkel

Sorry MCB,

we made 3 sets for 3 friends here, not more. The retracts are not commercially available

mitchilito

My Feedback: (7)

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.

MCB458

Thank you Detlef.............. would you sell the engineering drawings? I have access to full cnc machine plus 5 axis capability.

MCB458

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.

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.

mitchilito

My Feedback: (7)

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.

mitchilito

My Feedback: (7)

You'll have to get him to sell you the drawings for the new wings (required) as well

Detlef Kunkel

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.

Detlef Kunkel

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°

Detlef Kunkel

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

mitchilito

My Feedback: (7)

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.

MCB458

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.

MCB458

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....:-)

Detlef Kunkel

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)

mitchilito

My Feedback: (7)

That thing definitely looks bullet-proof Detlef! Also seems pretty light for its strength.

Detlef Kunkel

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

mitchilito

My Feedback: (7)

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!

mitchilito

My Feedback: (7)

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.

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. :-)

mitchilito

My Feedback: (7)

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. . . .

Detlef Kunkel

I dont mind the try.

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


And what you say about the power....completely true

mitchilito

My Feedback: (7)

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??

Detlef Kunkel

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?

Detlef Kunkel

Maybe this will brighten up your cloudy mood about the mixer :-)