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Old May 28, 2001, 09:54 AM
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Houston, TX.
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Anyone done a 90" Jack Stafford B-24 Liberator?

Check out the glo Liberator kit at http://www.cbpu.com/jackstafford/B-24.htm Now that would be a pretty bird and interesting electric project.

Anybody out there seen or heard of it being done, or know anything about how this thing atleast flys in its glo version?

Unlike the Joe Beshar 78" B-17 Royal Kit conversion I considered, this thing atleast comes with pre made cowls and foam wing cores. Heavy though it seems as 90" taint simple or cute!
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Old May 30, 2001, 03:59 PM
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Houston, TX.
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Ok, no takers. ???

How about changing the question to;

Does any body think this would be a worthwhile and doable project?

(-Figures, I'm the only one to post a topic amongst a whole slew, and get no replies except my own!)
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Old May 30, 2001, 05:17 PM
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Southington, Connecticut, United States
Joined Jun 2000
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Randy looks doable but remeber it has to he LITE!!!!! 90" is a lot of wing. but if the fusaloge was built with 3/16 foam board formers and contast grade wood it could be done.have fun stefanP
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Old May 30, 2001, 11:36 PM
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ifxmnfly:
Build it light enough, and 4 x S600 would do it. I saw a 120" span Martin Mars water bomber fly at Chilliwack last weekend using 4 C.G. Thrustmaster 540's, wired series/parallel, on 18x1700 cells, propped to draw 14A per motor, and flights were long and beautiful, and YES, it did roll and loop! See Todd Long's post in Open Discussion re "Chilliwack , thanks Ron" for a photo of this gorgeous giant.
Brad.
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Old May 31, 2001, 01:15 AM
It wasn't me...
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Trabuco Canyon, CA
Joined Nov 2000
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Quote:
Originally posted by Randall Miller:
Does any body think this would be a worthwhile and doable project?
Of course. It's both worthwhile and do-able.

Shoot, if I made an 88" wingspan Super Guppy fly on 4 geared-540 ferrites, you should be able to make this one fly pretty well. The Guppy weighed 13 lbs. and had a lot more drag than the B-24 would.

As others have said, keep it light, especially in the nacelles and nacelle mounting area of the wing. You should be able to save quite a bit of structural weight by going to electrics.

If you'd like to see what I mean, check out my brother and my guppy pages. (All About Guppys - http://www.thegrid.net/daren )

The trickiest part about building a multi-engined model has to do with the p-factor and torque coming from 4 motors/props rotating in the same direction.

You could simply add right thrust to all four motors, but there's a better solution. First, build a test rig and run all four motors at the same time so you can tach them. Then, with the motors running at idle, adjust the timing so they're as close to being synched as you can get them. You should be able to get them within a few hundred rpm of one another. It doesn't have to be perfect. In fact, it's better if they're slightly out of sync.

Now mark them so you know which the fastest to the slowest. When you mount them in the model mount the fastest as number 1, the next fastest as number 4, the next fastest as number 2 and the slowest as number 3.

As you can see, this will give you a natural right thrust that will counteract the p-factor and torque perfectly.

I hope this helps. Keep us posted on your progress.

Dan

[This message has been edited by DanSavage (edited 05-31-2001).]
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Old May 31, 2001, 07:23 PM
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Trabuco Canyon, CA
Joined Nov 2000
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Quote:
Originally posted by ifxmnfly:
Dan: What about counter rotating props? The motors don't care which way they rotate, assuming props are available.
You could, but it's not really necessary if you perform the procedure I described.

I look at it this way. You're going to have to sync the motors as best you can regardless of where you mount them on the model, so you might as well take the extra time to note their respective rpm's and mount them to limit the effects of the p-factor and torque.

The worst thing you could do is to not check and inadvertantly mount the strongest motors on the starboard wing and compound the problem.

Dan

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Old Jun 02, 2001, 10:19 PM
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10 lbs, 2 oz., ready to fly!
Brad.
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Old Jun 03, 2001, 01:12 AM
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Quote:
Originally posted by Brad Trent:
I saw a 120" span Martin Mars water bomber fly at Chilliwack last weekend....
Howdy Brad~

Any idea on the weight of the beast?
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Old Jun 03, 2001, 01:43 AM
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Houston, TX.
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What do you say Komet old buddy!

Gentleman, I have been getting some rather negative comments elsewhere about the Jack Stafford people. Seems Jack Stafford sold the company in 1986, and its had two new owners since then, with the latest people having the non-service friendly attitude of "We only box and ship the things, aren't modelers, don't know, don't care". Seems they tell you up front they can't do anything for you, or tell you they'll get back with you and then don't. I've had 3 different posts expressing VERY agitated modelers. The guys that are satisfied are usually guys that bought the thing years ago, under a different regime. Or, people that ordered one of the many different kits offered, were satisfied with what they received and had not had to have any requests or dealings with the seller after that. One guy said the plans were missing, but he was able to get them to send him a set. Still it's a reminder that the feeling of good and secure customer service is a nice thing to have, especially at high dollar. At $300.00 plus shipping I'm not sure I'm this brave. When I buy something over 20 bucks, I want to know I have someone to call up and talk with if there's a question or problem. I might be willing to take a gamble if all I hear is nothing but great things about the product. This product has some really disgruntled customers. Never mind the other posts telling of the just plain difficulty in building a kit that hasn't been updated since the early 70's.

Thanks a bunch for the technical info. BRAD and DAN. I'll take a note of it, since I am not familiar at all with electric. Whatever I do in electric it would have to be with the blessings of the experienced sales people who sell me the stuff. I run all these opinions by them for their final approval at the time of the sale. -Randall
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Old Jun 05, 2001, 06:58 PM
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Trabuco Canyon, CA
Joined Nov 2000
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Quote:
Originally posted by Randall Miller:
What do you say Komet old buddy!

Gentleman, I have been getting some rather negative comments elsewhere about the Jack Stafford people.

---

Thanks a bunch for the technical info. BRAD and DAN. I'll take a note of it, since I am not familiar at all with electric. Whatever I do in electric it would have to be with the blessings of the experienced sales people who sell me the stuff. I run all these opinions by them for their final approval at the time of the sale. -Randall
Randall,

Always remember there's two sides to any story. Yours and the butthead's.

Seriously, if you have any concerns, I'd suggest calling the company directly and talking to them for yourself.

Dan
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Old Jun 06, 2001, 12:14 AM
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Houston, TX.
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Ifxmnfly,
While I'm fussing with whether I might or might not, you're off the line and finished with the research already, and have your half price bargain spread out on the work table.

Well that settles that. Think I'll let you build it first! Now keep it away from the attic will ya?!! I want to hear how it flys before it doubles in price again! Especially like to hear from you when you're hot and heavy in the middle of the project.

Luck to you. Keep us Posted.
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Old Jun 10, 2001, 03:51 PM
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Houston, TX.
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Uh, huh. Like I said, I think I'll let you build it first.

You work fast! Let us know other pertinent facts while your building. Feel free to E mail me on usefull stuff you think I ought to know about your building experience. I'm writing this info about the wheel well so I avoid the same pit fall.
I wonder if they have since updated the plans.

By the Way. I know almost nothing about Electric flight and would have to rely on the advice of my salesman.

Excluding the receiver and retracts, and primarilly focusing on the power; What components is it going to take to get this thing up and flying efficiently $$$ ? You reckon $200. per cowl?
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Old Jun 12, 2001, 02:36 PM
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Chapel Hill, TN USA
Joined Apr 2001
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YOU MIGHT WANT TO CHECKOUT DAVE'S AIRCRAFT WORKS. HE HAS A 50"PLUS WS B-24 SLOPE OR THERMAL THAT DAVE THINKS WOULD BE A GREAT ELECTRIC CONVERSION FOR 4 SP400 MOTORS.
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Old Jan 02, 2003, 10:57 PM
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USA, OH, Newark
Joined Sep 2001
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I have a friend who started building one and he's thinking of going electric. Any suggestions on exactly which motors to use? Batteries? Two ESC's?

It calls for four .15 to .25 glow engines. Weight 9 to 12 lbs. Span is 90". Area is 740 sq in.

Thanks.
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Old Jan 02, 2003, 11:54 PM
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albuquerque
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Here's a pic of 72" Daves Aircraft Works conversion finsihed a couple of weeks ago, fly great, about 5lbs. Jim
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