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Old Dec 30, 2006, 08:46 PM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
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Twin Little Screamers Xb-70 Build

ok guys, heres a quick run through on the XB-70. powered by twin factory(cold) little screamers park jet motors, running 5.5x4.5 counter rotating props, 44" long, 25" wingspan, built from moddifed "fuels guy" plans, built using 6mm depron, and some 3mm, also, using a single(soon to be 2 1320 3s)2100 tp pl 3s, using castle creations thunder bird 18 esc"s, as 2 coats of poly, and son to get a light coat of white paint and decals. i had to guess at the cg becasue it wasnt on the plans, luckily, it was dead on. it flew great, only needing a little down trim(as i had put some up in to start, so it was just about nuetral) and it is a flaoter as well, only weighing 20.5oz. construction was very simple, and i built it in about 3 days. rvincent estimates the speed at 110mph(atleast ) as he was there to witness the first 3 flights. tried to run chase plane for me in his bae hawk , but was no match for the historic super sonic X bomber of the cold war that never made it into production, this beeing the first time teh xb70 has been in the antelope vally air in 40 years. bobs hawk was doing about 80mph, and i was cruisng at 60% power hanging with him it was alot of fun, and havnt found any bad habbits yet. it was getting about 8mni flights on the single 2100 3s, with alot of full throttle runs, and the motors never got remotely warm. using the factory settings on the CC TB 18's. so with the twin 1320 3's, i should be getting 12 minute flights at 330 watts(instead of a measily 265...... ) and olny adding 1 oz. its a great model, and as far as i know the onlyt one to build one so far on this site(pusher any ways) its a keeper for sure! any time a model impresses bob with speed, you know its sweet! when he first walked up and saw it, he said.."that thing is going to be awsome!" he also said "thats going to put my twin F-15 to shame!" thanks bob, i think it did too! :P wait till i get some more capacity in the battery compartment! anyways, i think bob thought it was going to be bigger! although, is has a pretty large pressance in the air. definately cool i was worried the inlets would dig in the grass, but it slid quite nicely! anyways, heres some pics, and a link to a few video clips from the maiden

http://www.rcgroups.com/forums/showt...87#post6639789
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Old Dec 30, 2006, 10:17 PM
That thing's operational!
birdlives1955's Avatar
New Orleans/Dallas
Joined Jan 2006
4,706 Posts
Yes! I have been waiting for this one! Congrats on the maiden flight CN! Neat stuff.
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Old Dec 30, 2006, 11:01 PM
Renegade Fun Forever!!
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Fontana, California, United States
Joined Jul 2004
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She hauls booty!! Looke incredibly smooth in the air too!! Thatnks to APC for making reverse rotation props This was the missing link for us twin powered guys
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Old Dec 30, 2006, 11:02 PM
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Malaysia
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Any link to the plans? ty.

edited : ah nvm, i got the plans already from parkjets :P me noob
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Old Dec 30, 2006, 11:10 PM
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corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
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link to the plans page....

http://www.parkjets.com/xb-70.html

theres 2 differnt plans, i used fuels guy's plans to base my model from, using the CG of teh other one posted. i felt FG'ss plans were closer to scale, thats why i went with his. made some changes though, as the plans dont seem to be all the way done, but are a great starting point.
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Old Dec 31, 2006, 12:38 AM
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Corsair Nut on the XB-70 have you put down drooped tips like on the real one?! if so would all of the annehedral be a control problem(to much roll like flipping up side down)
?
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Old Dec 31, 2006, 12:39 AM
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also if you did how would you stabilize it?
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Old Dec 31, 2006, 01:14 AM
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Seattle, WA
Joined Jun 2002
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GREAT work, CN! Man, that ship looks fantastic. The XB-70 has always been on my "must build someday" list, and twin LSPJs are the perfect power system!

Steve
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Old Dec 31, 2006, 03:26 AM
I've half a mind...
docrob's Avatar
New Delhi, India
Joined Jul 2005
2,600 Posts
Sweet, Brent.

You mentioned somewhere that tip stall might be a problem. Have you thought of putting in forced washout strips like Paul did in his Nighthawk? I know it'll take away from the scale looks, but will add a $##t load of functionality?

Doc
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Old Dec 31, 2006, 03:44 AM
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Winsen (Aller) Germany
Joined Oct 2003
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Brent,

she looks great in the air!! Congratulation!

Hey, you´ve visit a Hairdresser!

HJ
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Old Dec 31, 2006, 08:37 AM
AMA848091
St. Charles, MO.
Joined Apr 2003
493 Posts
corsair nut: Brent, that sure is a great looking group of toys, especially the XB-70. Fantastic build with the twin LSPJ's (which has be come a great motor) and the counter rotating prop's. Keep up the good work.

Cecil
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Old Dec 31, 2006, 10:18 AM
DELTAS RULE
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tehachapi, CA
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we had a big glider with drooped tips, and it flew like crap, we got rid of the anhedral, and it flew great! no tip stalls at all, the landing was very very slow, even without wind
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Old Dec 31, 2006, 12:01 PM
Live to fly, fly to live!
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New Bern, NC
Joined Dec 2003
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Quote:
Originally Posted by rvincent
She hauls booty!! Looke incredibly smooth in the air too!! Thatnks to APC for making reverse rotation props This was the missing link for us twin powered guys

I've got a dumb question....whats the difference? I'm curious because this could help out on our B-1B, but if I'm not mistaken J Morgans B-1B flies well with standard rotation props.

Great work CN....you've become a designing machine!

Paul
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Old Dec 31, 2006, 12:44 PM
Renegade Fun Forever!!
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Fontana, California, United States
Joined Jul 2004
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J's B1 has a ton of wing span! Also he uses very small props, so torque effect is minimal On my twin F-14 it made a HUGE difference in the launches!!! I used to have to put a FULL right input immediately after it left my hand, now I don't even need to touch the radio until it reaches the desired altitude. It just flies away.............................................. ............ smooth and easy
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Old Dec 31, 2006, 12:44 PM
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interesting story CN ill have to write that down
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