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Author Topic: MP Max Bee - Continuation  (Read 2628 times)

Offline Matt Piatkowski

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MP Max Bee - Continuation
« on: August 23, 2018, 06:16:38 AM »
Hello,
The project was left abandoned for the entire summer. I was in the EU flying another plane, participated in my first competitions, learned a lot and got a bit tired from driving in Poland, Czech Republic and Slovakia.

The time has come to build the wing to fuselage connection in my Max Bee and I am looking for options.

The one piece wing must be installed in the cutout of the fuselage from the bottom and secured with at least four 4-40 screws. Because the Max Bee logarithmic mechanism must be accessible for lubrication, I have decided to make the cabin removable. Also, I am planning to mount the carbon composite landing gear to the wing and this requires the box like, balsa and light ply structure attached to the wing's bottom sheeting and blending with the overall fuselage contour. Considering the stiffness, strength, weigth and access requirements, the connection represents a serious challenge.

I appreciate your suggestions and design ideas.
Regards,
M

 

Offline TDM

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Re: MP Max Bee - Continuation
« Reply #1 on: August 23, 2018, 08:29:31 AM »
Here is one idea. Laminate two layers of 1/16in balsa on a foam plug to make the fuselage shells. The plug can be made on a piece of MDF particle board put the formers on the MDF fill with foam in between them then shape the foam with sand paper using the formers as a guide and stop. Mold using water based glue and elastic band-aids.
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #2 on: August 24, 2018, 10:55:22 AM »
Hi TDM,
Interesting...
Still waiting for more replies.
Happy Flying,
M

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #3 on: September 06, 2018, 02:22:47 PM »
I have made some progress.
Please see the attached.
Flaps can move (+) (-) 30 degrees with this geometry of the links.

Next: building the wings take-apart connections to the fuselage and covering the wing.
Later,
M

Offline Crist Rigotti

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Re: MP Max Bee - Continuation
« Reply #4 on: September 06, 2018, 07:34:33 PM »
Why didn't you just continue the existing thread?  Now your build "thread" is 2 threads.
Crist
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Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #5 on: September 07, 2018, 11:32:45 AM »
Hi Crist,
I understand your concern but I have left the first thread inactive for such a long time that, when I wanted to add to it, the Stunthanger web site did not allow for that. I can combine BOTH threads if I am allowed to do it.
Happy Flying,
M

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #6 on: September 28, 2018, 01:28:14 PM »
MP Max Bee: continuation- Sept.28, 2018.
Main structural connection in the fuselage: wings and the carbon composite landing gear attachment rib (5 mm. epoxy glued plywood).
The fuselage firewall will allow for installation of MVVS 8.0 Kv=680 (shown), Cobra 3520/12/14 Kv=820/700 and Plettenberg 15-22 Kv=685.

6s and 5S batteries. Total of four different motor and batteries arrangements (three for 6S and one for 5S).
Happy flying,
M   

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #7 on: October 17, 2018, 08:33:28 AM »
Hello,
The wing and fuselage connection is almost finished. five short 4-40 an two longer 2-56 screws are used to secure the wing to the fuselage.
The access to the wing TE mounting screws, flaps horn and the logarithmic control system mechanism is from the top through the cutout in the fuselage horizontal shear panel (1/16" medium balsa with transverse grains, photo attached). This cutout will be accessible when the cabin is removed. The cabin will be molded as the carbon composite laminate and will provide torsional and bending stiffness and strength to the fuselage directly behind the wing TE. This is a separate interesting structural problem and I will show the details in this thread.

The carbon composite landing gear can be mounted for the hard surface and grass take offs and landings.

The plywood landing gear "box" is mounted to the wing that has been locally reinforced to react the forces and moments suffered by this area.

Only the open cells of the wing were covered with Polyspan. The rest of the wing was left uncovered and the entire wing was painted with the acrylic paint (photo attached). I will finish the wing with Doculam on top of the paint for stiffness and strength. This method was used and flight tested in my eParrot during more than 160 pattern flights. 

The weight of the wing right now is 400 grams and this includes the b-crank with the carbon composite pushrod, the almost completed wing to fuselage mounting structure and the flaps horn.

I expect the wing to weight about 500 grams when covered with Doculam and with flaps painted, doculamed and mounted.

Happy Flying,

Offline TDM

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Re: MP Max Bee - Continuation
« Reply #8 on: October 18, 2018, 03:24:37 PM »
Matt your workmanship is very good indeed. There are a lot of things still to do. Good luck.
Each goal you meet is a moment of happiness
Happiness is the harmony between what you think and what you do. Mahatma Gandhi

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #9 on: December 30, 2018, 08:24:05 AM »
Hello,
Please see the attached.

The firewall was cut using the PCB having 0.060" thickness. I will move the firewall aft as indicated by red arrow and will add two wooden, triangular shear beams (yellow triangles). These beams will reinforce the PCB connection in shear by increasing the area on which the thrust generated forces act.

The firewall will accept three motors: MVVS 8.0, Cobra 3520/14 and Plettenberg Orbit 15-22. They will be flight tested with 6S and 5S batteries. The use of 5S weighting almost two ounces less than 6S of similar capacity for the motors having Kv in 680-700 RPM/V range was recently discussed on this forum (https://stunthanger.com/smf/gettin-all-amp'ed-up!/motors-efficiency-52289/). 

Is 0.060" PCB firewall strong enough to survive the flight loads? When the motors are mounted, there is very little bending in the firewall because it is small. Shear stress generated by thrust, torque and the gyroscopic forces should be, in my opinion, properly reacted by epoxied wooden beams.

Your opinions, comments and friendly critique are welcome,
Happy Flying New Year,
M
 


Offline Crist Rigotti

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Re: MP Max Bee - Continuation
« Reply #10 on: December 30, 2018, 01:10:00 PM »
I've always used .125" FR4 for motor mounts/firewalls.  .060 seems really thin.
Crist
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Online MikeyPratt

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Re: MP Max Bee - Continuation
« Reply #11 on: December 30, 2018, 08:09:35 PM »
Hi Matt,
I agree with Crist .060 it to thin, I would make another one and laminate them together.  Are you mounting the firewall mount to the end of the fuse sides or inside of them?

Mikey


Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #12 on: December 31, 2018, 07:08:11 AM »
Hi Mikey and Crist,

Thank you for your comments.

I am mounting the firewall about 7/8" AFT from the front end of the fuselage. The current width of firewall is slightly too large to push it in between the fuselage sides but I will shave it to fit. Before I epoxy the firewall, I will completely finish painting and covering the model's fuselage and tail surfaces. The current RTF weight is about 59 oz. and this includes: MVVS 8.0 (8 oz.), Igor's 12x5 N prop. (0.64 oz.), spinner and prop. adapter (1.0 oz), ThunderPower 6S 2800 mAh. (12.75 oz.), Spin66 ESC (2.1 oz.), carbon L.G with 2.25" wheels, tail L.G with wheel, all screws and washers, 1.0 oz. of wing weight and 2.3 oz. of painting and covering with Doculam.

I will find the required C.G for the RTF model moving the firewall with MVVS FWD and AFT. I know already that the 6S battery must be pushed as far AFT as possible and the available range of the firewall movement  is 2.0" from the very front of the fuselage now.

Like I wrote, the plane will be tested also with other, lighter, motors with Plettenberg weighting 1.3 oz. less than MVVS. Because I am planning to experiment with 5S batteries having the same capacity like 6S and weighting, therefore, about 2 oz. less, the placement of the firewall must be carefully selected for all the motors and batteries combinations. My goal is to avoid adding the dead weight in the tail or nose area to get the C.G where it suppose to be.

I will consider doubling the thickness of firewall - the weight penalty is about 1/4 oz. for the second PCB piece and epoxy.

Happy Flying New Year,
M

Online MikeyPratt

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Re: MP Max Bee - Continuation
« Reply #13 on: December 31, 2018, 09:14:52 AM »
Hi Matt,
Sounds like a good plan.  Always best to arrange the components to keep from adding weight at any location.  Have you considered using the same battery pack as Igor?  Maybe slightly lighter if not removable. Keep up the great work and post more photos of the build.

Later,
Mikey

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #14 on: January 27, 2019, 05:49:26 PM »
Hello All,
I finished the plane today.
Please see the attached.
RTF weight is 1820 grams (64.2 oz.) with MVVS 8.0 and 6S 2800 TP.

When MVVS is replaced by Plettenberg 15-22 with fan, the RTF weight will be below 1800 grams (63.5 oz.).

The project was very demanding and time consuming but I learned many new things, especially regarding the take-apart large F2B competition models.

More photos will appear in this thread later.
Thanks
M






Offline Crist Rigotti

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Re: MP Max Bee - Continuation
« Reply #15 on: January 27, 2019, 09:54:22 PM »
Nice!
How many elevator hinges per side?
Crist
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Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #16 on: January 28, 2019, 05:47:07 AM »
Hi Crist,
The Max Bee plans show two large nylon hinges per the elevator side, the elevator was made using hard, solid balsa and the horn is well supported by two brass bushings.

Regards,
M



Offline Igor Burger

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Re: MP Max Bee - Continuation
« Reply #17 on: January 28, 2019, 06:04:36 AM »
If you do not count bushed horn at fuselage side, then I have either 2 wide Du-BRO hinges or 3 narrow in hard balsa inserts.

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #18 on: January 28, 2019, 07:32:30 AM »
Hi Igor,
I have used 2 wide Du-BRO hinges per the elevator side and they were epoxied in hard balsa on both ends.
Like I wrote, the elevator was made using hard balsa and I have made hard balsa inserts in the horizontal stabilizer T.E made of 1/4" thick medium balsa.

Comment: many months ago, I have made the build-up elevator that accepted the 3/32" dia. wire horn. When I put everything together for the first time in November 2018, I have noticed that this horn was too weak in torsion and decided to replace it with 1/8" dia. wire horn. At the same time, I realized that I would need a bit more weight in the tail area. The full hard balsa elevator is 10 grams heavier and the overall C.G location is now according to your plans, even with MVVS 8.0 (229 grams), when the 6S 2800 TP (361 grams) and Spin66 (58 grams) are moved all the way AFT in the battery compartment. This is the reason I needed to extend the leads between MVVS and Spin. It added 11 "leads" grams but allowed to keep ESC as far back as possible.

I have a question for you: how to secure Spin66 in such a way that:
1. The air flow around it is as free of obstacles as possible
2. The ESC can be moved FWD  and AFT in the battery compartment

I need to move the ESC FWD and AFT as the additional way of manipulating the model's C.G when other motors are used.

The simplest way is to attach the ESC to the battery using two small Velcro patches but it will obstruct the air flow around the ESC.

Also, I am not sure if the Velcro patches attached to the battery will stay attached when the ESC surface temperature reaches 55-60 degrees C.

These are the ESC temperatures measured in MPBee (my last year's plane) just after landing when the ambient temperature was 32-33 deg.C in shade and the day was sunny. 55-60 degrees C. measured on the ESC heat sink shrink cover means higher temperature of the ESC inside components and the limit temperature there is 110 deg.C. How much higher nobody knows but we all know that these heat related problems are a serious challenge, especially with the summers becoming longer and hotter.

Any ideas?

M




Offline Igor Burger

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Re: MP Max Bee - Continuation
« Reply #19 on: January 28, 2019, 08:17:27 AM »
You can see highest ESC temperature (it is FET temperature, so totally different number than you can see on surface of ESC) after flight, when you go to "Measure" and scroll down. So if you see it comes to 100deg, you have a problem to solve under 90 it is OK.

I have ESC exposed in flow (1" distance from warm battery), so I did not have problems with it. But my battery is not removable (for charging).

Offline Crist Rigotti

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Re: MP Max Bee - Continuation
« Reply #20 on: January 28, 2019, 08:29:50 AM »
Hi Crist,
The Max Bee plans show two large nylon hinges per the elevator side, the elevator was made using hard, solid balsa and the horn is well supported by two brass bushings.

Regards,
M

OK.  Thanks for the details.  Good luck with the ship.
Crist
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Electric - The Future of Old Time Stunt

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #21 on: January 28, 2019, 02:21:51 PM »
Hi Igor,
I have tried to use the numbers recorded by Spin66 last summer and had certain doubts seeing what was displayed by the JETI box when the "Measure" option was selected. There was another thread in which we, you and I, exchanged our opinions. I will find this thread. At this moment, I remember your conclusion: "we (F2B crowd) are lucky to have SPIN66 still available..." or something like that. I have agreed and our conversation was concluded at that time.

Again: I will find this old thread and refresh my memory regarding the content that was discussed.

Thanks,
M

Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #22 on: February 14, 2019, 07:36:51 AM »
MP Max Bee (recently christened The Big Red) components are shown in the attachment.
These fragile things must survive the air transportation in the veeeery long plywood box to the EU on April 02, 2019.

I promised myself never again build the wings in one piece. If I decide to build another F2B plane, everything will fit into much smaller and lighter box like Yatsenko or Solomianikov models.
 

Hi Igor,
Please see https://stunthanger.com/smf/gettin-all-amp'ed-up!/optimization-of-flight-parameters/msg530541/#msg530541 for our discussion about Spin66 "Measure" option. My response to you on August 17, 2018, 12:18:16 PM contains the conclusion.

Thank you,
M



Offline Matt Piatkowski

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Re: MP Max Bee - Continuation
« Reply #23 on: May 15, 2019, 03:50:44 AM »
Hello everybody,
MP Max Bee was re-named Big Red and this name will be used from now on.

The plane was equipped with Plettenberg 15-22 with cooling fan and with Igor's 12x5x3 carbon composite prop., Spin66ESC, Igor's active timer and 6S 2800 mAh. battery. I have made nine flights last week on 64' lines (eye-to-eye), changing slowly the level flights RPM.

From the first flight, I knew I built something good. The plane tracks and grooves beautifully and this means the C.G is where it suppose to be. The structure and all the connections seems to be strong enough to survive the accelerations caused by very sharp corners. I have tried squares, triangles and hourglasses, jerking the handle as hard as I could and there was no sign of structural damage. I will be experimenting with the in-flight level RPM, governed by the target throttle parameter and the sensitivity parameter of the active timer, to achieve the best balance between level flight speed, lines tension and the battery usage. Please expect further reports from the field. Regards, M

Offline Howard Rush

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Re: MP Max Bee - Continuation
« Reply #24 on: May 15, 2019, 04:36:36 PM »
I look forward to more reports. Thanks.
The Jive Combat Team
Making combat and stunt great again

Offline Matt Piatkowski

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Re: MP Max Bee - BIG RED - Continuation
« Reply #25 on: May 29, 2019, 06:29:26 AM »
My single motor Big Red weights now RTF 1845 grams and flies 5.1 sec. laps. The front of the fuselage has been rebuilt and reinforced with the carbon composite multi-directional fabric and I changed the motor from Plettenberg 15-22 to MVVS 8.0. Rebuilding added 18 grams (0.63 oz. ) and MVVS 8.0 is 1.0 oz. heavier than Pletty.

I have asked the Plettenberg Factory to exchange the shaft in the Pletty powering Big Red. The new shaft will be without fan and the weight of the motor will be 188-190 grams (6.7 oz. ) instead 201 grams (7.09 oz.) with the cooling fan.

Big Red with MVVS 8.0 flies well but after the motor change back to Plettenberg 15-22 without fan, it will fly better for sure. 1.0 oz. less at the nose makes a difference - in terms of the absolute weight and the pitching moment of inertia. The comparison of my plane with the planes using contra rotating propellers, show that the contra planes fly slower (5.2-5.4 sec./lap) and still maintain enough power to climb and in the OH maneuvers.

Regards,
M


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