RE: Composite-ARF Integral, kinda build thread
 

Mike,

I wasn't aware of the instances you noted below, so no argument. FWIW, I did have a vibration problem with my Neu setup, and it was because the aft support was loose.

For the firewall mounted outrunners, I am convinced the firewall needs to be very stiff, and if the firewall can be softened by heat from the heads of the mounting bolts, which allows the motor to become loose. Even a small amount of flex or looseness in the motor or mount can allow nasty vibration/resonance with either inrunners or outrunners.

I would note that the vast majority of electrics in recent years have run APC-E props, which makes it likely that any problems included the use of an APC-E prop (whether APC-E contributed to the problem or not). With increased use of CF props, it stands to reason that CF props will be associated with more problems in the future (whether the prop is the problem or not - and post mortem is quite difficult in most instances).

For the incidents you noted below, was APC contacted? APC has always been very proactive about researching/evaluating/understanding problems or potential problems, and in the past they have made improvements to props to resolve issues.

Regards,

Dave

RE: Composite-ARF Integral, kinda build thread
 

From my experience designing washing machines, I know that resonances in and around the operating speed of a rotating system can be a killer.

Also, I'm thinking that any motor that is mounted only at the front or the back, is going to behave somewhat like a weight on the end of stick, in that the stiffness of the attachment, the stiffness of the mount, or the stiffness of the adjacent fuselage could have a significant effect on the combined stiffness of the system.

If the combined weight of the motor, and the stiffness of the mounting arrangement conspire to create a potential resonance anywhere close to the prop rpm, then any slight offbalance in the prop could drive the system into an unstable resonant condition with the kind of events that Mike has been describing.

However, I'm a little less apt to identify the prop as the problem, because I'm reasonably certain that APC has made sure that the prop itself doesn't have natural frequencies anywhere close to the operating range of the motor / prop combinations that we run, and without this, the prop can only drive the system into resonance due to being unbalanced, without being an actual cause of the resonance.

RE: Composite-ARF Integral, kinda build thread
 

Thanks Dave . .

Sounds good. While I have had great success with APC props generally, I have thought the larger APC-E props to be a little too much on the flexible side for good efficiency (I'm NO expert, it's just a observation).

The APC range makes it a little more palatable (from a cost stand-point) to test different Dia. and Pitch, and trim and repitch and whatever . . I am thinking that testing different props and CF "stiffening" a preferred prop might be an option (and a bit of fun ;o).

Would I be correct in assuming that it would make a preferred APC-E prop BETTER ?? OR does the additonal stiffness change things? e.g. a pitch dimension less when carboned, etc. ?? What has been your observations ?

I have no idea what kind of additional stresses, in use, would be placed on the prop AFTER CF stiffening. One thing for sure . . I would hate a blade to decide it's had enough, and 'part company' [X(]

Maybe APC will bring out a range of E-Pattern props Carbon Reinforced ?? ! ? . . CAN YA HEAR ME, APC ?? ;)

Cheers, JB

RE: Composite-ARF Integral, kinda build thread
 

Brenner, Dave I respect all the input and your analytical minds. So I feel overmatched in the argument and this thread is supposed to be about the Integral. Which by the way is an absolute pleasure to own. I hate that the plane is being discontinued.
APC trust me they have gotten plenty out of most of us. They have been and continue to be #1 in RC props. I'm sure I've bought 100's of their props and not because I'm replacing broken ones. Just a lot of prop experimenting and power supply changes over the years.
Brenner I know what you do for Whirlpool and trust me it's highly respected.
Dave your a prop expert and I have followed your lead time and time again. Your point on mounts are all true.
Given all that all I will say is I'm a big fan of stiffer props. I do not like the flimsy tips on APC larger diameter E. props.
So here's a question. Will a prop (talking APC E.) running many many hours on an electric setup say a whole season or 2. Will it fatigue? Can the tips get out of track from each other? Thanks, Mike

RE: Composite-ARF Integral, kinda build thread
 

Mike,

I can only say in my experience, I've not seen an APC-E show the effects of age in terms of fatigue or tip tracking. Personally, I don't think I have many E props with more than 100 flights, and none with 200 (compared to some glow stuff where I have many props at 300, 400, 500+ flights). I know many years ago, APC had some prop tips fail in large scale warbird pylon. To recall the problem was traced to a resonance generated by one of the engines being used (a more common one to recall), and I believe the design of the prop was changed. To this day, APC has an advisory regarding resonances in airframes/motors/etc on their website.

I agree 100% with the discussion presented by Brenner. The suggestions I made regarding motors and mounting motors is derived from experience only, and I am sure Brenner could advise as to the difficulties of attempting to model/calculate various resonances of motors and mounts in various fuselages (of vastly differing construction quality and materials).

One item I forgot to mention, that ties in with what Brenner noted, is that I highly recommend using the plastic centering rings that come with the APC props. As is detailed in the APC instructions and on the APC website, the pilot hole in the prop is not a precision hole, but the larger recessed/countersunk hole on the backside is a precision surface and the use of the centering rings is required to ensure the prop is centered on the propshaft. Opening up the pilot hole from the front with a tapered reamer ensures that the prop does not try to bend the prop shaft. http://www.apcprop.com/v/html/tech_s...html#holealign Quite honestly, I never noticed a problem with the pilot hole when running glow, but I have a number of electric installations that appear very critical to prop balance. Balancing the prop should be done with the centering ring in place. For motors that require the prop to be drilled to a larger diameter than the biggest centering ring, I jig the prop in a drill press, centering it using a drill bit that just fits inside the centering ring. Then I put in a larger drill bit to open the hole in the prop. If, after opening the hole in the prop, it is no longer balanced, then the hole is offcenter and the prop should be discarded.

Again, no argument here, just trying to share information and learn what can be learned, and progress forward for all.

Regards,

Dave

RE: Composite-ARF Integral, kinda build thread
 

Jeff,

I have shared all my data with APC, and they have examined some of the CF props I made. For those that know the history of APC, they are continually improving the design of their props based on new data (whether theorized or empirical).

APC uses an injection molded production process....which allows very precise and cost effective production. APC has done some very limited number of props in CF, but it dramatically increases the price, and is not a direction (business model) they have chosen to pursue.

I would encourage everyone to check the APC website which contains quite a bit of info about how the props are designed and made, and share your interests/concerns with APC as they have always been a proactive supporter of competition flying.

Regards,

Dave

RE: Composite-ARF Integral, kinda build thread
 

Well,.... that explains the "Spin Cycle" p-mix I saw on your radio! [8D]

Joe

RE: Composite-ARF Integral, kinda build thread
 

Hi Dave . . good info.

I am aware of the APC prop manufacturing process. I actually do business with the Injection Moulding company in Adelaide (Australia) that manufactured all Bolly Nylon props (Glass Filled Nylon, I believe).

My thoughts were not of a seperate range of APC Carbon props, but rather a post layed-up CF reinforcing of their standard GFN? props. Possibly only the rear face of the prop? Sure, it will add cost, but shouldn't be anywhere near the cost of a full Carbon prop . .

Anyway . . it's all interesting?

Cheers, JB

RE: Composite-ARF Integral, kinda build thread
 

A friend has a 90 size electric pattern ship that vibrated and screeched at wide
open throttle with an APC e prop and is smooth and silent with a XOAR wooden prop.
I use an APC e prop on my pattern ship with no problems. Maybe it has something
to do with the mounting method, mine has nose mount with a rear support bearing
and his is front mount only.

tommy

RE: Composite-ARF Integral, kinda build thread
 

Jeff et al,

I am going to start a new thread for the APC topic in the pattern forum.

Regards,

Dave



[/quote]

Hi Dave . . good info.

I am aware of the APC prop manufacturing process. I actually do business with the Injection Moulding company in Adelaide (Australia) that manufactured all Bolly Nylon props (Glass Filled Nylon, I believe).

My thoughts were not of a seperate range of APC Carbon props, but rather a post layed-up CF reinforcing of their standard GFN? props. Possibly only the rear face of the prop? Sure, it will add cost, but shouldn't be anywhere near the cost of a full Carbon prop . .

Anyway . . it's all interesting?

Cheers, JB
[/quote]

RE: Composite-ARF Integral, kinda build thread
 

Minor tragedy today . . . lost my canopy inflight and it smashed the leading edge of the right side stab. All is repairable and I recovered the canopy, but I was wondering if someone has pictures of a more secure canopy mechanism that I can copy. My current system was two prongs in front, two hooks on the side, a spring latch on the rear and 3 pieces of tape. I think the tape lost its sticky in the 40 degree air, but thats not really relevant.

As always thanks for any help.


JP

RE: Composite-ARF Integral, kinda build thread
 

Get a longer hatch latch. I never liked the BVM one that I put on there in the first place.

RE: Composite-ARF Integral, kinda build thread
 

Ryan - do you know if Joe Hayes is still thinking about selling the twin to my plane? Can you shoot me a PM with his email if he is.

Thanks,

JP

RE: Composite-ARF Integral, kinda build thread
 

Has anyone converted a C50 powered model to a Pletty powered model? If so do you have any tips to offer?

Thanks as always,


JP

RE: Composite-ARF Integral, kinda build thread
 

No, but I've replaced firewalls.

Grind out the old firewall, glue and all, and put the new one in. Installing a Pletty firewall is no different from any other firewall installation in a composite fuse.

RE: Composite-ARF Integral, kinda build thread
 

Yep. Did it right before the Worlds. Nothing to it. Remove the old stuff with a dremel to within 1/4" of the fuselage (or closer if you dare) and install the new firewall. You will have to open the nose of the plane to 60mm for the motor to slide in from.

If you use this template, just change the side slots/openings to 2 each rather than single long ones. Then you shouldn't need the carbon support. [link=http://www.electric-f3a.com/Documents/Integral-Plettenberg%20firewall.pdf]firewall[/link]

RE: Composite-ARF Integral, kinda build thread
 

Thanks for the pics, and the template! Chris Moon has offered to give me a hand with this project so hopefully I'll get it right the first time.



JP

RE: Composite-ARF Integral, kinda build thread
 

Sunny, did you just get the plane that started this thread? It's famous![8D]

RE: Composite-ARF Integral, kinda build thread
 

lol, that first plane unfortunately is no longer around.

RE: Composite-ARF Integral, kinda build thread
 

Jason, thanks for the pdf with the 2 templates. Did you use the original thrust settings, or use Chad's template with the thrust offset when you retro fit the firewall in your Integral?

Thanks
Woodie

RE: Composite-ARF Integral, kinda build thread
 

I used the original as I didn't change my wing/stab alignment. The plane that Sunny has though the wings are changed.

RE: Composite-ARF Integral, kinda build thread
 

Jason, Mine has a piece of cardboard stuck behind the motor as a shim. Is that because the wings are adjusted? And I guess this is obvious, but when I change to a Pletty I should put the new motor mount off by that 1 degree?

Thanks for your patience!


JP

RE: Composite-ARF Integral, kinda build thread
 

Also . . . real quick . . . what would you say are the major differences between a Pletty powered Integral and a C50 powered one?

RE: Composite-ARF Integral, kinda build thread
 

Use the offset mount in that Integral since the wings have been moved. Don't mount it lined up with the nose ring, should require less down thrust.

Noise ;), oh and no maintenance

RE: Composite-ARF Integral, kinda build thread
 

Hi
just started to convert my old Integral to el. the old firewall is removed and found the PDF that shows Chad's firewall with the Pletty.
I think I understand correclty that the center off the Pletty is in the middel off the screws that holds it?

The engine I will use is a cheap China Axi copy ...if I work it works if not I maybe change it for a Axi ...
When you fly with a el. engine you use a bigger prop and remeber the old days with glow that you got change in the need for right thrust , but the rmp on the el.engine is lower do I need to make the right trust diffrent ?
With the YS I had 1,5 mm more that the nose indicated and that was perfect.