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Old Oct 11, 2005, 12:03 PM
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USA, TX, Diana
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Top Flite Contender Convert To Electric?

I am preparing to build a Top Flite Contender from a kit. I am considering electric power. Does anyone have an electric powered Contender?
Wingspan: 53 1/4" Wing Area: 660 Sq. In Weight: 6 - 61/2 lbs.
(2721 - 2948 grams) Recommended engine: .40 - .61 glow

This would be my first electric so I need help in selecting the motor (brushless), ESC, etc. Can you help me?

If someone does have a electric Contenter, how does it perform?

Thanks
Jim Vines Jr.
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Old Oct 11, 2005, 12:22 PM
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No, but man would that be nice! Great to see some classic planes still being offered.

I say go for it. Many good power systems for that type of ship. AXI would be near the top of my list

Here are a couple of good threads for power systems on similiar ships:
http://www.rcgroups.com/forums/showthread.php?t=374258
http://www.rcgroups.com/forums/showthread.php?t=298734
http://www.rcgroups.com/forums/showthread.php?t=357478
http://www.hobby-lobby.com/brushless-axi4120.htm

Mike
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Old Oct 12, 2005, 12:05 AM
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Thanks, Pda, for the links. When I start building I may start a building thread.
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Old Oct 12, 2005, 08:21 AM
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Originally Posted by safebet
Thanks, Pda, for the links. When I start building I may start a building thread.
That would be great.......I miss mine, great flier.
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Old Oct 12, 2005, 08:26 AM
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I remember that the Contender was offered as a plan by Dave Platt in the late, lamented American Aircraft Modeler, about 1968 or 69. It was touted as being very light for its size, with details like using MonoKote to cover the turtle deck instead of sheeting it. Should be a great conversion.

Also offered in that issue was a neat low wing sport job called Suds, which also had nice features for an electric conversion.

Post pictures and do the build!

Marten
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Old Oct 12, 2005, 08:45 AM
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Hi Jim
I've thought about this one myself at times - it is something of a classic and even looks good, which is sadly lacking in many places these days.

The one thing that puts me off - that trike UC. They do nothing for me personally - I've only had three trike gear models since my first RC model in 1979 - but the biggest worry is that they heavily restrict the prop diameter. Okay, you could stretch the legs a little before the UC starts looking utterly goofy, but they will still offer clearance for a relatively small prop. My favourite electric of all time has to be my Four Star 40 - which flew best on a 15 x 10, which a taller taildragger main gear cleared easily and didn't look dumb in flight or on the ground.

I'd go along with the AXI idea, though I admit to little knowledge in that area beyond my 2820/10, which has proven to be a great 10 cell motor. One of them will keep the prop diameter down better than many of the geared motor options. The MaxCim and some sensorless units behind the MEC gearbox would be worth considering, as you can swap gear ratios across a wide range, to match a motor to a prop, rather than vice-versa. It's still much cheaper to buy a new pinion than a differently wound outrunner motor

Structurally, read through everything you can lay your hands on about converting 40-ish glow kits. Funnily enough, a vast percentage of it will mention the Four Star ... Glow kits are usually well overbuilt, even the 'lightweight' ones, with the biggest weight savings usually being in the nose area. All that weight of 1/4" firewalls, beam mounts and massive fuselage doublers is there to anchor a vibrating, pounding infernal consumption engine. With an electric, the model's often off the deck before full power is reached (okay, mine is ) and all the firewall feels is pull and torque. I hang 700W motors onto 1/8" Birch ply firewalls in all my designs now, and they are glued to 1/64" ply doublers inside stripwood fuselages with 1/8 x 1/4 longerons.


Wingspars and ribs are another area. Die-cut kit ribs are mostly from very hard balsa as die-cutting prefers harder wood for a cleaner cut - modern laser cut kits usually are better here. I'd use a kit's ribs as templates for decently light and stiff 1/16" copies, for starters. My other favourite is to toss the kit's mainspars and use 1/4 x 1/8 spruce, sometimes doubled out to around half span - though my latest 5.25lb aerobatic model doesn't have those doublers and can take it - with interspar webbing that starts at 1/4" in the middle, tapering through a couple of bays of 1/8" and then down to 1/16" webbing to the tips.

It's the old control line flier's saying "It's easier to take 1 gm off 100 pieces of a model than to try and take 100gm off the finished model".

Then you need to build in battery access - again, go read! If you don't build in battery access, you will undoubtably find yourself fussing at some future time ...

Good luck with the project, it's a good looking and well proven flier, you should do okay with it.

Regards

Dereck
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Old Oct 12, 2005, 11:04 AM
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Jim,
The Contender looks striking in the air because of it's shape. They are also great flyers with an OS .61 in the nose.
That said, IMHO this is not a good candidate for "electrocution". I'm not saying it can't be done.....but......you would just have to re-do so much of it. As Dereck has pointed out, it would need to be changed over to a tail dragger to allow for a larger, more efficient prop (the ability to run that larger, more efficient prop is one of the primary advantages of electric power .... so you would not want to give that up). The hard, die cut, parts are heavy (Dereck said this too) ....and the construction is way overbuilt (makes it even heavier) compared to the modern laser cut kits you see coming on the market today.
If this is to be your 1st electric model, suggest you take a look at the construction of a SIG 4*40, or 4*60. This is what you want for electric power.
Again, I'm not saying this can't be done. It will just be a LOT more work to achieve anywhere near the same performance level you could have with another choice. If you are prepared for that going in ...... and choose to proceed anyway .... then I'll help you with power train recommendations, or in any other way that I can.
Ed
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Old Oct 12, 2005, 11:27 AM
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Conversion Or Not, That Is The?????

Thank all of you for your comments. Such input saves us beginners a lot of frustration. I have a brand new OS .61 FX I purchased for this kit. In light of the shared potential propeller problem, I may just stick with the OS as suggested.

I also have a Great Planes Super Decathlon 40 that I am preparing to build this winter. Do you think it could be a potential good candidate for electric. I think a .46 glow is recommended for it.

Thanks, again for the comments. Very much appreciated.

Jim Vines Jr.
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Old Oct 12, 2005, 06:58 PM
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Jim,
I'll be glad to help, but I can't find it ?? Great Planes ?
Could it be another mfg ?
Ed
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Old Oct 13, 2005, 09:19 AM
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Quote:
Originally Posted by safebet
Thank all of you for your comments. Such input saves us beginners a lot of frustration. I have a brand new OS .61 FX I purchased for this kit. In light of the shared potential propeller problem, I may just stick with the OS as suggested.

I also have a Great Planes Super Decathlon 40 that I am preparing to build this winter. Do you think it could be a potential good candidate for electric. I think a .46 glow is recommended for it.

Thanks, again for the comments. Very much appreciated.

Jim Vines Jr.
Having a fair amount of time in converting 40-ish models to glow, one observation is that Great Planes kits are fine in the aerodynamics area, but are engineered by, and for, people who can't spell 'weight'.

They start off with heavy balsa - because that looks better when they make die-cut parts from it - and use lots of Liteply - which die-cuts well, is cheap and also very heavy for its pathetic strength.

My most personal connection with GP was my CAP 232. This good looking, great flying aerobatic ship ended up with the cowl and rudder out of the kit - everything else bar the canopy was re-designed structurally to what I considered necessary (and even the canopy was a specially moulded one, in thinner material, done by a 'friendly inside contact' ). I halved the weight of the mainspars alone, from 4 to 2oz, and my second fuselage saved over six ounces over my first, which was heavily "dieted" from the glow kit structure to start with.

My Four Star 40, OTOH, mostly got a hatch in the top deck, some internal radio re-arrangement to allow for a huge battery, and a longer UC. At the far endof the conversion scale, that little parkflier Cub I'm holding in my avatar (Sig's 84.5" 1/5th scale J3 kit) was built right out the box, and had two ply plates added, to accept the battery packs. All I modified was the cut-outs in the firewall to accept my particular motor.

If you're not used to higher power electrics, do like Ed says and start with something relatively "simple". A high winged model can be a real pain when it comes to battery access - which is real nice to have for NiMh cells, and absolutely essential for the safe operation of LiPos (imagine a LiPo bursting into flames inside your model ...). A low winged sports model only needs a fuselage top hatch for pack access, which anyone who understands which is the best end of a balsa knife to hold can build in real easy after reading this forum some.

This can lead to complications - I built my 4*40 to practice handling a 700W electric set-up while I got on with the CAP 232. Ended up, I enjoyed flying the 4* so much that I bought another motor for the CAP so I could carry on flying the model I only built to get my "new toy" airborne! I still have the 4*40 - now over 5 years old, while the CAP moved to a new owner last year.

Having said all that, the Contender is a classic good looker - someone needs to electrocute one! But I've never figured out how to retain its looks with a taildragger - retracts might be the answer, but they are a load of fuss for a sports flier whose nearest site is mostly pretty rough grass.

Regards

Dereck
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Old Oct 13, 2005, 09:35 AM
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Quote:
Having said all that, the Contender is a classic good looker - someone needs to electrocute one!
I agree, I even think you might be able to do it with Trike gear and 3blade prop. Not ideal, but it is such a great classic plane and needs trike gear!

There has to be room for a 13.5" prop....
http://www2.towerhobbies.com/cgi-bin...?&I=LX1633&P=7
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Old Oct 13, 2005, 02:42 PM
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Come on then - which photoshop ace is going to take out the ugly single jug and fit one with a wing mounted taildragger setup? It's not even like the appearance is a sort-of jet with a fan on the front of a simulated nose intake, but with no jet efflux hole in the back end - it's still pretty much a prop driven aircraft at heart.

I always feel a bit leery of the lack of dihedral. I know that BARFmakers love it, because it's a cheaper way to build a wing than doing it properly, but a flat wing has never worked even half-way decent for me on a low wing configuration.

Still, with what I've changed on kits, adding a little dihedral (2 deg usually works on 5:1 AR, give or take a smidgen ) is no great challenge.

Do recall reading somewhere about how you could build the wingtips so they came up level with the top of the wing, to give some dihedral effect, but I have been known to be wrong before

MaxCim 13Y, 12 or 14 BRJ feeding 45A on max chat through 2.5:1 gearing - need a 12 x 10 - 12" or thereabouts?

Unfortunately, I have to deal with a Plantraco steered indoor model first, then there's this S400-ish sized "model for real people" design I'm working on for a RealWorld (tm) magazine, so someone else will have to take this challenge

Regards

Dereck
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Old Oct 13, 2005, 03:20 PM
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Common Dereck do it..............................

You have the technology you can rebuilt it...

Tower Hobbies called, they need your CC number!

Mike
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Old Oct 13, 2005, 05:06 PM
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I appreciate all of the comments. It has been interesting and informative reading. I really like the pics.
That is one sharp looking plane. I look forward to starting the build in about a month.

In light of the comments, I guess I will stick with the OS.61 FX in the nose of the
Contender. The Contender is a Top Flite kit and the Super Decathelon 40 is a Great Planes kit. I think it will require a .46.

I hope to build both of them in the next 3 or 4 months. Like to have them ready for Spring. I am still flying with an instructor on a Hangar 9 Alpha 60, so I need a lot of flight time before I am really ready for either one. I may just purchase an ARF electric for a second plane. Something that with step me up a notch in preparation for the Contender and the Decathalon. Fortunately, I live in East Texas, and we do have some good flying weather, even in the winter.

From what I've read they both can be a handful for an experienced pilot, especially the Decathelon. I won't fly either until my instructor says I am ready, and then that, too, will be on a "buddy box."

I am so glad I found this forum because I have found very knowledgeable people that are sincerely willing to help and offer suggestions, that ultimately will save me time and $$$$$.

Thank you, again.

Jim Vines Jr.
"In God We Trust"
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Old Oct 13, 2005, 05:09 PM
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I could add some dihedral during the build of the Contender, huh?

Jim Vines Jr.
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