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Old Nov 30, 2011, 12:16 AM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
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F-8 Crusader mods for J-Power

I received this 50mm F-8 and saw that it needed some help to be a Crusader. At $65, I'm not complaining...it's a great start on a cool jet.

First, the intake is way too large as is the fuselage, so a pie slice was removed down the length, from in front of the engine, all the way to the intake.

Looks better already, but the cockpit is too close to the wings. I sliced off the cockpit and traced a template on some plywood. This was used to hot wire 16 sections of blue foam for the required 3 3/4 inches of missing
fuselage. Old school, laser would be better, but no got...

I'll post more progress, right now it's fill and sand...

Joe
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Old Dec 01, 2011, 02:35 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
629 Posts
Out of paint at the moment, so she's a bit rough, but she's ready for test flight.

Motor swap gets an honest 150 watts/16 amps at WOT. No scorcher like the
big brother, but should be fine...it's one of those long can 20x40x3.00 jobs, you know, the purple ones. Kit impeller presses on the motor very nicely. Translated, I can't get the impeller off the shaft after I test fitted it...after many run-ups and different throttle settings, trying to shake it off, it won't budge, mostly because it's very balanced and smooth...so we'll see.

To make up for added weight, I threw out the 3 servos and went with tailerons using two 3 gram servos. I ended up adding 35 grams over stock weight with the fuse extension, tailerons and motor/esc swap. With the J-57 afterburner motor, this should be OK...

Joe
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Old Dec 01, 2011, 02:36 PM
DELTAS RULE
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tehachapi, CA
Joined Jan 2006
22,833 Posts
wow! starting to look like a F-8! great work!
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Old Dec 01, 2011, 02:49 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
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Thanks, CN! ...and deltas do rule...along with stubby winged stovepipes...
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Old Dec 02, 2011, 12:05 PM
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Joe 1320's Avatar
United States, FL, Sebring
Joined Feb 2006
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Creative work! I think the designers were confused and took and A-7 shape and turned it into a F-8. Check the elevator incidence. Many have reported the plan acts tail heavy, the nose pitches up and you enter a flat spin to teh ground. A few other models were known for this and upon checking, the tails were indeed given a molded in up incidence. Most correct it or fly the thing really nose heavy.
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Old Dec 02, 2011, 02:23 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
629 Posts
Thanks, Joe!

Yep, after getting the model, I was surprised I had an A-7 in my hands with a nice F-8 paint job...VMF 312, the 'Checkerboards' out of MCAS El Toro, served combat in VN before handing their F-8E's in for F-4's...well, that's good enough for me!

Tonight was the test flight, but the wind forecast is not too good.

Thanks for the heads up on the elevator incidence problem. I'll trim slightly down elevator from factory mold marks, then. The full flying elevators pay off here...checking if the incidence really is out of wack will be easy.

The wings on this plane are rather small and over weighting them would be easy. The fuse at this scale is 30 inches. Combined with the tiny stock motor/fan, a toss ending with a sight similar to a javlin...if you're lucky...would probably be the result. Even motoring up has to be carefully considered, again due to the small wings. I'm about 70 grams over the 325 allowed. I don't think the stock weight was right either, though, should have read 350 grams flying weight, according to my scales. Regardless, wing loading is at the max end of the scale, so I'll let you guys know the results of the test flight.

Joe
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Old Dec 02, 2011, 04:28 PM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,507 Posts
Cool foam work! Take the edge of a spoon and a straight edge to connect your pannel lines thru the fuse addition.....just push the spoon edge in lightly and drag against the straight edge for a nice line to match the others. I learned the trick repairing foamies!
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Old Dec 02, 2011, 05:58 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
629 Posts
Thanks, AA...good tip, that will leave a nice heavy line. My method for years has been an old, dull pizza wheel cutter on a straight edge. But makes a fine line, not the heavy lines that are on this model...I'll try your tip ...

Joe
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Old Dec 02, 2011, 11:12 PM
Live to fly
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Sacramento
Joined Apr 2005
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Excited to give this one a run! Hope the winds calm down! Nice job as usual Joe!!
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Old Dec 03, 2011, 03:40 PM
Registered User
Cincinnati OH
Joined May 2007
494 Posts
F-8 Crusader

Quote:
Originally Posted by redlite View Post
Thanks, Joe!

Yep, after getting the model, I was surprised I had an A-7 in my hands with a nice F-8 paint job...VMF 312, the 'Checkerboards' out of MCAS El Toro, served combat in VN before handing their F-8E's in for F-4's...well, that's good enough for me!

Tonight was the test flight, but the wind forecast is not too good.

Thanks for the heads up on the elevator incidence problem. I'll trim slightly down elevator from factory mold marks, then. The full flying elevators pay off here...checking if the incidence really is out of wack will be easy.

The wings on this plane are rather small and over weighting them would be easy. The fuse at this scale is 30 inches. Combined with the tiny stock motor/fan, a toss ending with a sight similar to a javlin...if you're lucky...would probably be the result. Even motoring up has to be carefully considered, again due to the small wings. I'm about 70 grams over the 325 allowed. I don't think the stock weight was right either, though, should have read 350 grams flying weight, according to my scales. Regardless, wing loading is at the max end of the scale, so I'll let you guys know the results of the test flight.

Joe
Joe:
I built an F-8 from scratch and I really like your work..as I have the JPower F8, but I have not decided if I want to try and mod it. you are right on the money about the really tough situation when doing an F-8 becuase of the fuselage length and the small wings...mine required quite a bit of thrust to fly well and it needed flaps on landing to reduce the speed..


Good luck!
Sarge
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Old Dec 03, 2011, 08:05 PM
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Waltjg's Avatar
Crystal River Fl.
Joined Jul 2008
3,681 Posts
Joe,, great work!!! Nice looking bird now,, are you going to finish the detail and repaint?
Sarge,, good to see you on here again,, awsome plane there! Going to make seff this year???? w.
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Old Dec 03, 2011, 10:20 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
629 Posts
@ bighead...Thanks, tomorrow looks good for test flight.

@ jg...Thanks, if things go well then she'll get paint and details.

@ sarge...WOW, that is one beautiful model. Never seen the RF-8 version, absolutely outstanding! Thanks for the great shots.

We'll try to get a video and pics of the test flight. Final AUW is 401 grams...can't think of any more ways to lighten it up. I feel it should scoot OK, if not, I can always open a cheater hole to see if that helps, but for now, it's going up sans hole.

Joe
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Old Dec 03, 2011, 10:49 PM
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Cincinnati OH
Joined May 2007
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F-8 Crusader

Walt:
yes..no doubt...I'll be at SEFF this year!!

Sarge

Quote:
Originally Posted by Waltjg View Post
Joe,, great work!!! Nice looking bird now,, are you going to finish the detail and repaint?
Sarge,, good to see you on here again,, awsome plane there! Going to make seff this year???? w.
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Old Dec 04, 2011, 10:04 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Sacramento CA
Joined Oct 2009
629 Posts
The maiden went well with bighead on the sticks. The plane is very fast and likes to fly straight ahead. The tailerons were not the best idea...a normal elevator and small ailerons about mid-wing are the next mod to try. I'll let you know the results as this plane doing a high speed low pass is beyond cool...made the project worthwhile and some more time spent on the plane is in order.

No cheater hole is required, speed is more than adequate. Also, the full size plane had ventral fins, something this model could benefit from. Ben flew two flights on two 3s 850's which gives about 4 minutes of high to medium throttle settings. She flew nicely at half throttle, too.

Someone shot video so I'll try and get it.

Joe
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Old Dec 05, 2011, 12:56 AM
Live to fly
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Sacramento
Joined Apr 2005
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It flew great! A hair touchy but very cool!! Can't wait to try it after the next mods!
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