It is currently Tue Feb 25, 2020 8:54 am

All times are UTC - 6 hours




Post new topic Reply to topic  [ 106 posts ]  Go to page 1, 2, 3, 4, 5 ... 11  Next
Author Message
 Post subject: My Summer Pattern Project
PostPosted: Tue Jun 24, 2014 2:52 pm 
Offline
User avatar

Joined: Thu Aug 16, 2012 12:08 am
Posts: 458
While I've dabbled in just about every discipline/activity in this hobby, my first true love has always been pattern. I've been flying in pattern contests off and on since I was about 13 (41 now). I've been taking a break for the last couple years since I sold my last plane, but now it's time to get back in.

Ordered a BJ Craft Competition BiSide from http://www.F3AUnlimited.com and it got here today. Also ordered the motor, mount, and spinner. The motor is a Plettenberg Advance 30-10, and spinner is a ultra-light Falcon spinner. My plan is to get the motor mounted up first and then do the radio install in a couple weeks.

Airplane is interesting. Biplane, composite fuse, built up wings and tail feathers, full flying stab. Weight should be in the 4800g range w/ 10s 4500s.

Going to be a lot of fun getting back into competition, I miss it.

Tom M



ImageImageImageImageImageImageImageImage

Sent from my HTC One_M8 using Tapatalk


Last edited by exfokkerflyer on Tue Jun 24, 2014 4:26 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Tue Jun 24, 2014 2:55 pm 
Offline
User avatar

Joined: Thu Aug 16, 2012 12:08 am
Posts: 458
Here is what the finished product will look like.

Image

Sent from my HTC One_M8 using Tapatalk


Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Tue Jun 24, 2014 3:03 pm 
Offline
User avatar

Joined: Mon Jul 25, 2011 11:58 am
Posts: 4962
Location: Austin, TX
Wow, that is seriously cool. And what a huge motor! :)
Can't wait to see more pics. :thumbup:

_________________
Chris Boultinghouse


Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Tue Jun 24, 2014 3:07 pm 
Offline
User avatar

Joined: Sun Jul 31, 2011 3:43 pm
Posts: 2513
Location: Houston, Texas
Will follow with interest

That was some serious packaging!

Thanks for sharing

_________________
Home of Burntwood RC


Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Tue Jun 24, 2014 3:09 pm 
Offline
User avatar

Joined: Sun Jul 31, 2011 3:43 pm
Posts: 2513
Location: Houston, Texas
I just noticed you said full flying stab!

Why is that not used for 3D planes?

And what is the benefit for pattern planes?

_________________
Home of Burntwood RC


Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Tue Jun 24, 2014 4:25 pm 
Offline
User avatar

Joined: Thu Aug 16, 2012 12:08 am
Posts: 458
The motor is a 230 kV INRUNNER (yep, not a typo) and weighs about 590g. It's a solid chunk of a motor, but weight wise is lighter than the Axi and older larger out runners I used to use. I have used Plettenbergs in the past, was actually my first large electric motor in about 2005, right at the beginning of the "electric revolution". I believe it was a 25-10, very underpowered for pattern but the plane was extremely overbuilt as well. This plane is several generations newer and weight won't be a problem. Motor is very smooth and is supposed to be a beast.

Honestly the flying stab hasn't really been that popular in pattern. Every once in a while you will see it pop up on the latest and greatest, but they never really catch on. I'm not sure why this designer, BJ Park, went this way exactly. The model has evolved over a little bit of time and he tried different variations and settled on this for feel. It's intriguing to me because one of the most important parts of a build for me, for any model but especially pattern or aerobatic, is to ensure the elevators operate exactly the same. This becomes important when trimming a model to ensure that when you push or pull on the elevator stick the model goes exactly where you want it, not drifting excessively left or right.

Some of the pattern planes use two mini servos for the elevators, others use carbon rods actuated by a single servo (marketed at one time as Dual Elevator Pushrod System DEPS) which was my favorite method. With a flying stab, it is fairly simple to ensure the stab halves operate in unison with one servo. This also eliminates the necesity for an adjustable incidence stab, since the elevator takes care of that.

I plan on getting the motor installed next week, have to place an order for some supplies. I have stopped using epoxy for applications like this and moved to hysol. Cure time is a lot longer but it stays where you put it and does not flake off light composites like epoxy can.

Tom M


Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Wed Jul 02, 2014 10:39 pm 
Offline
User avatar

Joined: Thu Aug 16, 2012 12:08 am
Posts: 458
Got started on the build today. Not sure if there is any interest on a full blown build thread here, not sure I am up to it even if there is interest! :D Another pattern flyer did a write up on RCU about building this plane, but it was written for those who have built planes like this already. There were a lot of posts like, "I installed the motor and it was very straight-forward..." Well, if you have never built something like this, straight-forward is a complete mystery. So that's where I started with the build.

I bought a mount, pictured below, that has both a front and rear support. The idea is to glue in a hardwood or otherwise stiff ring to the front of the plane from the inside. Then you attach the motor to the mount, and screw the mount into the ring. Very simple, very clean, and allows you to shim the motor for thrust adjustments and also easily replace the motor should you change your mind somewhere down the line.

Problem is, it didn't fit. the fuselage is much more narrow than I thought, the ears of the mount won't allow the motor to go far enough forward to clear the nose ring. Okay... so plan B.

Tom M


"


Attachments:
File comment: Mount that I intended to mount motor to the airplane.
IMAG0258.jpg
IMAG0258.jpg [ 2 MiB | Viewed 8279 times ]
File comment: Taken from the back of the hatch looking forward. Notice there are no formers, guides, firewalls, etc.
IMAG0254.jpg
IMAG0254.jpg [ 1.48 MiB | Viewed 8279 times ]
File comment: Front from the nose ring looking through the fuselage.
IMAG0256.jpg
IMAG0256.jpg [ 2.01 MiB | Viewed 8279 times ]
Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Wed Jul 02, 2014 11:12 pm 
Offline
User avatar

Joined: Thu Aug 16, 2012 12:08 am
Posts: 458
The only real way to mount the motor is to now attach it to a firewall inside the fuse. The tricky part is to get the spacing correct. In a perfect world you just get a disc of plywood and shove it up to the nose ring from the inside, drill some holes and boom... there you go!

But, the spacing is the tricky part. Somehow you have to space the firewall far enough aft to allow the thrust washer on the motor to just clear the nose ring so you have a tight, almost flush, fit with the spinner. How do you do it?

Some guys will guestimate where the motor should sit and take something that will hold it's shape, like heavy gauge solder or something, and lay it inside just about where the firewall will go. You should be able to get an approximate shape to trace onto card stock or cardboard from there. Then once you get that in the right spot, then you can transfer to what ever material you are going to use for the firewall.

Today I just eyeballed it. I put the motor in the fuse, letting the thrust washer just peek out, and just eyeballed about where the firewall would go. I then looked at the fuse from the top, saw that at that point, the fuse is about 5mm wider than the nose ring. So I traced the spinner on cardboard, and cut it out about 5mm larger, in more of an oval shape towards the bottom. Test fit, trim, test fit, trim... once I got it about right, I put a dot in the center as viewed from the nose ring. From there, I used the metal mount, that didn't fit, and used that to trace the holes onto.

I cut out the holes on the cardboard firewall and mounted it to the motor. It's important for not only the spacing to be correct, but to have it centered within the ring so the spinner fits properly. Doing this just gave me a good idea about what shape the firewall should be. I didn't spend a whole lot of time getting this exact. I would still have to fit the actual firewall exactly, and that would require sanding and trimming anyway. The point is to get the approximate shape and size and have the motor mounting holes in the firewall in their correct position.

I transferred the shape to the firewall and centered the central hole for the shaft. I made sure the firewall was too big, since it's easier to sand away material than to add it. In fact, if it's too small, goes too far forward, you're done, it's unusable. Which happened to me with the first piece. I sanded just a bit too much away, and when I put everything together to check my progress, the spinner would end up being about 1/8" out from the ring. That's too much. The ideal is just a few mm...

You can use plywood for something like this, 3/16"-1/4" will work fine. I'm using a carbon fiber reinforced plywood plate, brand name Dragonplate, for this that is just smaller than 3/16" thick. And it's STIFF, you can not get this material to flex at all. Great stuff.

When I made the second one, I made it much larger and took my time sanding it down. It's important to take your time with this. Sand a little bit, test fit with the motor and the thrust washer to check your progress. I used a table mount belt sander to get the shape right and to fine tune the fit. But you have to be careful, it's way too easy to sand too much.

With this motor, and out runners as well, it's important to cut out the cooling holes. The spinner has holes to allow air in, the backplate also has spokes that are shaped like an impeller to pull air through. You need to create someplace for the air to go. Even if you are not using a spinner like this, you can always cut the tip off a plastic spinner to allow air to flow through. Makes a difference.

Tom M


Attachments:
File comment: Cooling holes opened up completely. Used a rotozip bit to clear out the excess material.
IMAG0264.jpg
IMAG0264.jpg [ 1.03 MiB | Viewed 8278 times ]
File comment: The motor mounting holes have been drilled as well as the center hole to allow for the shaft. Cooling holes are started with a 1/2" drill bit, using the metal mount as a guide.
IMAG0263.jpg
IMAG0263.jpg [ 2.58 MiB | Viewed 8278 times ]


Last edited by exfokkerflyer on Thu Jul 03, 2014 2:32 am, edited 6 times in total.
Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Wed Jul 02, 2014 11:39 pm 
Offline
User avatar

Joined: Thu Aug 16, 2012 12:08 am
Posts: 458
Once it's close, it's time to get it fine tuned. I will have the motor attached to the firewall with the thrust washer on. Holding it in place I put the spinner backplate on, then a spacer (a prop hub will work for this), and then screw the prop nut on and secure it up. I sometimes cut out a thin plywood spacer to place behind the spinner, so that when you tighten down the prop you are sandwiching the nose ring between the motor and the spinner. This is how you will glue the firewall into position, assuring proper alignment.

Not wanting to try to find the right piece of plywood. I used some double sided tape attached to the back of the spinner. That wasn't quite the right size, and two layers was too much, so I just used some card stock attached to the tape to get the right spacing.

With this all in place you can see if the spinner is in the right spot, aligned properly, and whether or not your firewall is making contact with the fuselage. It does not have to be a perfect fit here, you are looking for it to be mostly in contact, the gaps can be filled later.

If you have to sand the firewall, be sure to take the motor off the firewall first, you don't want to get debris inside the motor, especially if carbon is used.

Once you are satisfied with the fit, the spinner is flush with the sides of the nose ring, the gap between the nose ring and backplate is adequate and consistent (the spacer should accomplish this), then it's time to glue. Personally, this is when I get a cold drink and sit and look at it. Is it REALLY in the position I want? Once I decide that it is... then I get a snack, watch a TV show, take a walk... then come back and ask myself the same question. Sometimes I even sleep on it.

Today, a snack and a session of holding kids and chatting with the wife for a minutes was enough...

I took it all apart again, and got out my Aeropoxy. That's what it's marketed by Bob Violett Models (BVM) by, but it's a two part aerospace grade epoxy... industry name is Hysol 9462. You can get a starter kit from BVM for just under $100, that gets you the glue, a gun, tips, all you need to get started. If you do a lot of composite work with large airplanes, it's a must have. The best part is that it's thixotropic, meaning it won't run. It stays where you put it, which makes it perfect for things like this. It sets in a few hours, fully cured in about a day or so.

Even though the Aeropoxy won't run, I wrapped the motor in electrical tape to prevent any damage or any glue getting stuck where I don't want it. I placed the Aeropoxy on the firewall all the way around, and put it all together. I will let it sit for about 12-18 hours before I take the spinner off and check my work.

Once this is done I'll attack the rear mount/support. Maybe this weekend.

Tom M


Attachments:
File comment: Shown from the rear, you can see just a bit of Aeropoxy that has squirted out below the motor.
IMAG0266.jpg
IMAG0266.jpg [ 1.46 MiB | Viewed 8278 times ]
File comment: The spinner is fitted to the assembly, and checked for fit. This was actually taken after the Aeropoxy was applied, so I'm basically done now until the glue sets.
IMAG0265.jpg
IMAG0265.jpg [ 1.11 MiB | Viewed 8278 times ]
File comment: The motor is test fitted with the spinner and prop hub then tightened down.
IMAG0261.jpg
IMAG0261.jpg [ 2.13 MiB | Viewed 8278 times ]
Top
 Profile  
 
 Post subject: Re: My Summer Pattern Project
PostPosted: Thu Jul 03, 2014 6:51 am 
Offline
User avatar

Joined: Mon Jul 25, 2011 11:58 am
Posts: 4962
Location: Austin, TX
Looks like you're off to a good start!

_________________
Chris Boultinghouse


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 106 posts ]  Go to page 1, 2, 3, 4, 5 ... 11  Next

All times are UTC - 6 hours


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group