Author Topic: Imitation conversion to electric (Read 10793 times)

Igor Burger · « **Reply #50 on:** October 15, 2009, 12:56:03 AM »

Quote from: Dean Pappas on October 14, 2009, 08:57:53 PM

So our friends at AXI are working on the special problems posed by Stunt?

Unfortunately not, the only thing they did for us is special 2826/13D with kv=680 I0=1.5A and Ri=42mo ... it has little better copper filling and its low KV saves some mAh if used with 6S A123 and 12x6.

We wanted stronger motor (for more watts) but they have a gap in production and nex bigger motor has too large diameter. But for now I am happy with smaller models. I think it is not very good idea to battle with large heavy model in wind :-)

Some guys here try to use motors from MVVS ... they do motor MVVS 8 which looks good for 5 lipo cells, but I do not see reason to play with new motors now.

Alan Hahn · « **Reply #51 on:** October 15, 2009, 07:56:38 AM »

Igor,
I am pretty convinced that we really aren't pushing the motors we have right now--in terms of the power we are asking them to put out.
I think I would agree with you that pushing them somewhat harder will cost us more watts from the battery, and probably a lower efficiency in converting the battery watts into watts delivered to the propeller. So you would need a bigger battery to offset this. I am not sure how everyone else is pushing their current battery setup to the 80% wall, I thought I was probably the one nearest that edge.

But the heavier battery would need to be compared to a heavier motor.

Igor Burger · « **Reply #52 on:** October 15, 2009, 08:16:42 AM »

Regarding battery I am on 95% ... but it is A123, so does not matter.

Regarding motors, I thought it is not so bad, but the guy from AXI wanted to see what we do with them, because when I told him we have 6 cells with 12x6 on AXI 2826/12 he told me it MUST burn. He did not know that 6sA123 on governor is something else, but anyway, he tried temperature and he told me we have to go with the temperature down. The only reason for that is bearing which is not preprared to work full time at so relatively high rpm without oiling (so not problem with magnets, winding, efficiency).

But my Axi after whole seasone (~300 flights on that one model) looks like new. So I do not know, it looks good, and you are probably right, but if I should go to higher power (if), I thing it will really need bigger motor. Just to be sure that it is safe and that I can without any questions fly it whole season in seriouse uninterrupted practice and competing.

Dean Pappas · « **Reply #53 on:** October 15, 2009, 10:15:21 AM »

Mike,
The RC pylon guys use direct-drive inrunners at very high RPM. They don't have that issue.
There's a whole thread devoted to Neu 1900 motors for that reason. <www.neumotors.com>

Igor, the problems I have encountered have all been bearing related, and because I have not caught a motor before it went bad I cannot tell whether it is bearing failure causing the seat in the aluminum to loosen, or the other way around. Both are very plausible! I would be glad to provide an example of a problem-child motor!

regards,
Dean Pappas

Bill Ervin · « **Reply #54 on:** October 20, 2009, 11:20:54 PM »

It's white again Yea! Only took me a month and a half to get the plane back to where it was in the first post!

And you guys hijacked my thread!

When the moderator finds out you guys are gonna be soooo busted...

doh!!... never mind.

Crist Rigotti · « **Reply #55 on:** October 21, 2009, 05:03:52 AM »

Bill,
Looks good. I'm sure the finish will be impressive. I've seen your work. 2 months to go!

Dean Pappas · « **Reply #56 on:** October 21, 2009, 07:54:42 AM »

Quote from: Bill Ervin on October 20, 2009, 11:20:54 PM

And you guys hijacked my thread! When the moderator finds out you guys are gonna be soooo busted...

doh!!... never mind.

Bad moderator! Bad, bad!

Bill Ervin · « **Reply #57 on:** August 31, 2011, 09:13:49 PM »

Well... after almost two years of head scratching I think I've figured out a method of installation...

First, a quarter inch was removed from one edge of the timer board while being careful to not get too close to any circuit lines on the back. I still had an eighth of an inch to spare. A new mounting hole was drilled, it's the one just over the letter R.

Bill Ervin · « **Reply #58 on:** August 31, 2011, 09:19:39 PM »

Then a lite-ply "mother board" was made for the esc and timer. The timer is held with a pair of nylon 4-40 screws and the esc is held with Velcro.

Bill Ervin · « **Reply #59 on:** August 31, 2011, 09:21:36 PM »

This is what the speed control looked like when I hacked the leads down.

Bill Ervin · « **Reply #60 on:** August 31, 2011, 09:24:00 PM »

Now I had a sub-assembly. The back of the Lite-ply board has Velcro applied.

Bill Ervin · « **Reply #61 on:** August 31, 2011, 09:27:52 PM »

The motor and battery(ies) also got their leads trimmed really short.

Bill Ervin · « **Reply #62 on:** August 31, 2011, 09:32:05 PM »

All told over an ounce of wiring was removed. This was good as I had some concerns about a possible nose-heavy condition.

Bill Ervin · « **Reply #63 on:** August 31, 2011, 09:40:27 PM »

First the battery gets slid into it's cavity from the inboard side. I gave up on the idea of using an a123 pack for this project. I'll come back to it on the next plane. Shown is a 5s 3000 pack, I would have liked a little more capacity but the price ($25!), weight (13 oz.) and physical dimensions work!

Bill Ervin · « **Reply #64 on:** August 31, 2011, 09:47:56 PM »

And here's everything wired up. Wished the battery manufacturer and Castle would have coordinated their efforts so the discharge leads didn't have to criss-cross, oh well.

After programming the esc a short run-up was made. Hmmmm... If I don't shoot on a quick coat of colored dope soon I might have to just fly an all-white plane this Labor-Day!

Bill Ervin · « **Reply #65 on:** August 31, 2011, 09:54:08 PM »

To swap out the battery disconnect the discharge leads and remove the mother board. I'll let you guys know how it works in the heat of battle (108 degrees F today in Las Vegas, sheesh

)

Next pics will be with color and letters etc. I promise it wont take another two years.

Bill

Bill Ervin · « **Reply #66 on:** September 25, 2011, 11:01:08 PM »

Well, it's definitely red and it's definitely an Imitation! Trim colors next, planning for yellow numbers and letters with an 1/8" dark blue border, a blue canopy w/shading, some ink maybe.

Might have made the lettering a touch on the big side

. Which, of course, means the first time I bring it out to the field one of my flying buddies is gonna ask what it is.

PerttiMe · « **Reply #67 on:** September 26, 2011, 01:49:15 AM »

Now I want to know if it flies too

Is the battery held in with friction and inertia only, or do you have something else there to secure it?

Bill Ervin · « **Reply #68 on:** September 26, 2011, 06:12:52 AM »

Just friction and inertia but some sort of strap arrangement could be made. Those "cooling holes" I cut on the starboard side have proven to be quite useful for pushing the battery out using a couple fingers.

Bill Ervin · « **Reply #69 on:** October 02, 2011, 10:18:35 PM »

Got some time to work on the plane yesterday. Next step was to mask off the red on the top of the wing and spray the numbers and letters a nice, bright lemon yellow. I normally use Cub Yellow so this is a step outside the comfort zone. $:-\$ The problem is that the mask would run over into the adjacent letter/number unless I made one, huge and labor intensive mask for the entire "Imitation" and then another for my entire AMA number. That's not going to happen.

I already had the negative mask for each character from when I masked off the wing and then painted the red. The solution was to mask and paint every other character and complete the task in two sessions.

Here's the results of the first 3-hour masking session. The decision was made to not go for a 1/8" blue border because the line between the red and yellow turned out nice and sharp. Thank Goodness!

Crist Rigotti · « **Reply #70 on:** October 03, 2011, 09:22:16 PM »

Getting close. Just in time for the weather to start cooling off!

John Rist · « **Reply #71 on:** October 04, 2011, 09:13:59 AM »

Looking good! Any concerns about battery cooling? Also will the battery heat cook loose the Velcro?

Bill Ervin · « **Reply #72 on:** October 04, 2011, 12:02:57 PM »

Good things to consider John. There is about 3/16" clearance around the battery and I did put some cooling holes on the right side of the compartment. The fit of the battery is made as tight as possible using ~1/8" Depron foam spacers. I'll make sure to cut those spacers small to allow for more airflow. If the batt gets hot enough to melt the Velcro adhesive I'll probably have other issues too!

I'll let you know how it all goes. Bill

Bill Ervin · « **Reply #73 on:** October 04, 2011, 10:36:25 PM »

Snuck in a masking/spraying session after work today. All the numbers and letters came out very good. I wouldn't call the color combo coordinated or soothing to the eye, but it is flashy! My father would call it garish and I would have a hard time arguing the point. There was this Jetco Navigator hanging from the ceiling of the Apache Plaza hobby shop in Minnesota back in the early 70's painted up in these colors. Funny part is the lettering appears to be Cub Yellow in this Image!

Sneeking in some time with the model puts this day in the win column!

Dean Pappas · « **Reply #74 on:** October 05, 2011, 09:37:45 PM »

A Jetco navigator ...
Now I wish I had that old kit that was up in my Dad's basement rafters. Somehow over the years, it flat disappeared

Dean

Author Topic: Imitation conversion to electric (Read 10793 times)

Alan Hahn