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Author Topic: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6  (Read 2760 times)

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Offline Andy Hoffer

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #30 on: February 21, 2021, 06:50:46 PM »
@Frank v B , do not let @Andy Hoffer  comment on your pictures, rather let him show us what he is building...

Hi @GuyOReilly,

I thought you'd never ask!  I am actually assembling an illustrated encyclopedia entitled The Many Faces of @Frank v B

Watch for it at Bookstore Spijkerman (De Bergen district in Eindhoven), Boekenberg (also in De Bergen), and Bookstore Van Piere.  It will be full of great ideas for your next aircraft pilot mannequin.  8)

Andy

Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #31 on: February 21, 2021, 10:14:29 PM »
Installing the retracts

Approach- do all the fiddly stuff on one side to get it to work, then copy it exactly on the other side.

To reduce the rib compromise from 3 to 2 ribs, I made the landing gear 3/4" shorter than the plans and used wheels one size smaller.

The Bearcat has a very high stance on the wheels so by reducing it, it looks more normal.  The clearance is still enough to be able swing a 9" prop.  My guess is that I will be using about a 7-8" prop.  Have not decided on the motor yet.  Will do it when I have an relatively accurate flying weight.

Frank

Andy, I am not changing anything.  If the depth of field is perfect and the resolution is perfect you will be able to read everything.  That would spoil the challenge. ;D
Guy, Andy doesn't build anything because it would lead to you and me making his life difficult. ::) "I'm in the revenge business". ;)
Ben, I am not changing anything because that would involve reprogramming my brain.  Never a good outcome expected.  ;)
« Last Edit: February 22, 2021, 08:41:49 AM by Frank v B »
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Offline GuyOReilly

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #32 on: February 22, 2021, 05:03:46 PM »
Guy, Andy doesn't build anything because it would lead to you and me making his life difficult. ::) "I'm in the revenge business". ;)

So @Frank v B does that mean operating cannons and machine guns or bomb drop?   ???

Guy

Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #33 on: February 22, 2021, 10:45:57 PM »
OOOOOOHHHHHHHH!!!  Looks good.

 Just had to spend 15 minutes to make the wing fit.  Had to do it to figure out where the retract servo could be installed.

Both retracts are in place as are the retract servo rails.

Frank

ps: Guy- MAAC rules don't allow anything to be fired from a model airplane.  Tempting as it may seem at times. ;)
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Offline Andy Hoffer

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #34 on: February 22, 2021, 11:28:40 PM »
HEy @Frank v B

Love the attitude tape on the tail!  :D

Andy

Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #35 on: February 23, 2021, 10:46:30 PM »
YYYESSSS!!!!  The retracts are in and working. 
They work surprisingly well....coming from a skeptic who thinks all retracts are sent to us from a greater power who is ticked off at us. ;D

Notice the servo (Hitec HS-55) is sticking out from the bottom.  The wing still has to have the rounded bottom added to follow the round bottom contour of the fuselage.  Those stringers will cover this servo bottom.

Next- making some wheel wells so the wing structure is not open to everything.
These retracts will have taken three building days to install.

Will attempt to attach a short video of some retract cycles.

Frank

« Last Edit: February 23, 2021, 10:49:50 PM by Frank v B »
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Offline Andy Hoffer

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #36 on: February 24, 2021, 08:31:54 AM »
These look great @Frank v B .  I presume you will fly gear up (belly landing) until the gear-stripper runway is replaced at TEMAC!  8)

Looking forward to your landing gear cinematography!

Andy

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #37 on: February 24, 2021, 06:04:57 PM »
Here is the video of the landing gear cycling.  It was attached to a GreatHobbies servo cycler and a 4 cell RX pack.
Thanks to Oscar for modifying the video so I could post it. 



Frank

ps: There is no truth to the rumour that I want to build a Trireme using this technology.   ;)
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Offline sihinch

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #38 on: February 24, 2021, 06:34:46 PM »
Could the pilot not decide about whether to land Frank?!  ;D

Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #39 on: February 24, 2021, 06:49:53 PM »
Simon,

Indecisiveness kills when flying. ;)

The video show pre-programmed go-arounds. ;D

F.
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Offline Andy Hoffer

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #40 on: February 24, 2021, 07:15:42 PM »
Hi @Frank v B

So, if I understand this correctly, you hold the starboard wingtip, turn on the retracts, confirm that they are flapping properly (I assume at a much more energetic pace than that shown in the demo video), and then launch the plane into the air.  How many watts do you get per flap cycle?  Brilliant concept really:  just slow down the flapping when you want to land, then lock them in the gear down position just before touchdown.  Eliminates the whole ESC, motor and prop thing which just add weight and complexity.

Hats off to you Sir!

Andy


Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #41 on: February 27, 2021, 08:58:30 PM »
Gotta keep going.  Am doing the small stuff to get closer to the finish line.  A couple of decisions made:

- sheeted the bottom of the wing around the retracts so the covering can adhere to solid wood.
- attached the wing with two nylon bolts, one in the front, one in the back.  two reasons: i) This is really a mid-wing model.  The fuselage below the wing requires the wing be lifted straight up to remove.  It cannot have a dowel on the leading edge because it requires the wing to fit in at an angle. Hypotenuse issues.
ii) a bolt at the front and the back makes the wing a significant contributor to the strength of the fuse.  The wing acts as a brace.
- Landing gear covers- found a way to make the landing gear covers fit to the retracts.
- added corner braces around the edges of the ailerons/flaps.
- Magnetic battery hatch- started making the magnetic battery hatch at the bottom of the nose.  It will be sheeted, not open stringers.
- the bottom of the fuse under the wing will be sheeted and not open structure with stringers.  In case it needs to be hand-launched or belly landed.
- added spar braces around the dihedral joints.

Will probably start covering the model in the next few days.

F.
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Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #42 on: March 04, 2021, 10:39:13 PM »
Have been chipping away at it.  Just started the final sanding before starting the covering.

Next assignment:  Power plant!

Weighed the parts:
- wing, incl. retracts, wheels, aileron, flap and retract servos (4)          5.1 oz
- fuse (incl rudder and elevator servos)                                              2.7 oz
- tail feathers                                                                                   0.6 oz
- Rx, 12 amp ESC, battery                                                                 2.1 oz
                                          Total                                                    10.5 oz

Still to come are the motor, motor mount, cowl, covering, canopy and pushrods in the fuselage. 
This plane will be safely below 16 oz.

The motor would have to be around 100 watts.  Will go through (a deep dive of) my collection of brushless motors. ;D

Frank
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Online Frank v B

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #43 on: March 06, 2021, 02:50:14 PM »
A deep dive of my BL motor cupboard brought out a speed 400 equivalent brushless motor.
The match shows it to be about 110 watts on 3 cells (12 amp continuous).  It is also a very light motor.  I don't think it is a robust motor so no prop strikes allowed.

Done in the last day:
- installed the pushrod housing for the elevator and rudder.
- installed the motor.  It is a firewall mount (not X mount).  Put an X mount around the shaft and built a balsa box so it would come out of the cowl properly.
- made the cowl.  Cowl magnet and registration pin installation is next.
- made the tail block- the fuse part that comes to a point where the former and stringers end.

The covering can start after dinner.

Frank

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Offline Andy Hoffer

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Re: Frank's Dumas Bearcat RC conversion- 30" span- Covid build #6
« Reply #44 on: March 06, 2021, 05:50:53 PM »
A deep dive of my BL motor cupboard brought out a speed 400 equivalent brushless motor.
The match shows it to be about 110 watts on 3 cells (12 amp continuous).  It is also a very light motor.  I don't think it is a robust motor so no prop strikes allowed.

Done in the last day:
- installed the pushrod housing for the elevator and rudder.
- installed the motor.  It is a firewall mount (not X mount).  Put an X mount around the shaft and built a balsa box so it would come out of the cowl properly.
- made the cowl.  Cowl magnet and registration pin installation is next.
- made the tail block- the fuse part that comes to a point where the former and stringers end.

The covering can start after dinner.

Frank

Hi @Frank v B ,

Ijou reallij should sell tickets for events like this.  Ijou could make a pile of gilders and paij for replenishing ijour RC goody stash manij times over.  To saij nothing of the entertainment vaijue.  Ijou might want to consider posting a IjouTube clip of ijour next dive!!! 8)

Andij

« Last Edit: March 06, 2021, 05:56:59 PM by Andy Hoffer »