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Re: XM-708

Posted: Tue Jul 23, 2013 5:58 am
by JimC
vtduece, I've been trying repeatedly to do that on two different phones, a Droid Bionic and a Note 2. No luck.

I own a PA-11 and a PA-12 as well. The J3 is my favorite. Mounted an O-200 by 337 rather than STC so I wouldn't have to install wing tanks.

Re: XM-708

Posted: Tue Jul 23, 2013 6:35 am
by xm708
here is the plane you guys.. Jef which dump was local georges one ?

Re: XM-708

Posted: Tue Jul 23, 2013 8:26 am
by vtdeucedriver
JimC wrote:vtduece, I've been trying repeatedly to do that on two different phones, a Droid Bionic and a Note 2. No luck.

I own a PA-11 and a PA-12 as well. The J3 is my favorite. Mounted an O-200 by 337 rather than STC so I wouldn't have to install wing tanks.
Nice!! I worked for a banner tow company in s.fla for 6 yrs. we did just about everything you can do to make a cub have more lift. Got a j-3 certified with a 0-360 and a PA-18 with a O-540 and endless mods to back that up. Stuff that cub crafters is doing now was already at work in S.fla.



To Ed, yes on George's! Still kicking myself.

Re: XM-708

Posted: Tue Jul 23, 2013 8:38 am
by JimC
I've heard about that O-360 J3.
I don't follow 18's too closely, but several have mounted 540's
One 18 clone has mounted an IO-720.

My favorite though is a J3 with an O-200 and 9.5:1 pistons and a Mac 7535 prop. Carrying the same payload (light), about 25-30 feet in the air when a 160 HP 18 breaks ground.

Re: XM-708

Posted: Tue Jul 23, 2013 8:45 am
by JimC
vtd, you might be interested in another flying critter that I work on (flapping flight mechanics and biomechanics). Quetzalcoatlus northropi, one of the largest animals that ever flew. Wingspan slightly larger than a J3, stood 14 feet tall on the ground, could stand flatfooted on all four legs and reach the tip of its snout 23 feet in the air.

Re: XM-708

Posted: Tue Jul 23, 2013 9:36 am
by vtdeucedriver
JimC wrote:I've heard about that O-360 J3.
I don't follow 18's too closely, but several have mounted 540's
One 18 clone has mounted an IO-720.

My favorite though is a J3 with an O-200 and 9.5:1 pistons and a Mac 7535 prop. Carrying the same payload (light), about 25-30 feet in the air when a 160 HP 18 breaks ground.
The 180hp J3 was a hoot. We put a 18 overhead on it, put 3 degrees of droop on the inboard wing ribs, stretched the wing and added Vg's and a leading edge cuff. It would later get a gourney flap at the trailing edge. Had great lift but no more cruise speed with that 360 out front.

Re: XM-708

Posted: Tue Jul 23, 2013 9:46 am
by JimC
The wickerbills (gurney flaps) help a lot with only a minor drag penalty.

Cruise speed increases with the cube root of the power ratio, so it takes a LOT more power to substantially increase the speed (8 times the power to double the speed).

Re: XM-708

Posted: Tue Jul 23, 2013 9:47 am
by JimC
Anybody have a photo of the 708 safety shield?
And of the stock tailgate?

Re: XM-708

Posted: Tue Jul 23, 2013 1:42 pm
by xm708
Jim

I was too lazy to back mine out and take a pic. This is a link to Cabell Garbee's xm708 page it shows the tailgate quite a few times..

http://www.garbee.net/~cabell/dumptruck/xm708index.htm

Re: XM-708

Posted: Tue Jul 23, 2013 3:44 pm
by jim lee
JimC, what did you do on the Quetzalcoatlus northropi project?

I just looked it up an Google and had some fun reading about the big 'Ol bird.

-jim lee

Re: XM-708

Posted: Tue Jul 23, 2013 4:26 pm
by JimC
Quetzie wasn't a bird and wasn't closely related to birds.

I work on the flapping flight mechanics of the articulated membrane wings, the launch mechanics, the generation of command authority, and the biomechanics.

On the skeletal replica that hangs in the lobby of the Texas Memorial Museum in Austin, I did the anisometric morphs of the missing bones projecting up from the smaller Quetzalcoatlus species (which I much prefer working on -- better preservation and more specimens). I worked with Wann Langston, Jr. on the two animals from about 1997-1998 until his death last March. I work on other pterosaurs as well, but these are my favorites. I miss Wann.

If you are talking about Paul MacCready's QN replica project, it was before my time. Paul and I did become friends after I started working on the animals. He gave me a good many of his in-house design calculations and test videos of his preliminary prototypes. I miss him too. As an aside, we refer to the animal as Qn and Paul's robotic emulation as QN. The emulation was articulated only at the shoulder and did not use a membrane wing. He also had to put an impossible bend in the neck because the emulation flew with legs retracted (unlike the real animals)

Re: XM-708

Posted: Tue Jul 23, 2013 4:51 pm
by JimC
Me out in my front yard holding a left humerus of Quetzalcoatlus northropi.

Sorry, board software says jpeg is an invalid file type. Can't post the photo.
Tried it on a different phone. Now it says, "Sorry, board attachment quota has been reached".
Arrrghh....

Re: XM-708

Posted: Tue Jul 23, 2013 7:10 pm
by xm708
look what Mr.Ed found tonight. This is number 11 supposedly residing at the Kodiak Alaska military museum awaiting resto she is rusty and crusty but still a little dumper..

Re: XM-708

Posted: Wed Jul 24, 2013 11:12 am
by JimC
I went out to the airport this morning and measured the back the bed of the 708, came home and drew it up in AutoCad. Now I understand how the top hinge pin release works (slick -- I'm impressed).

When I start drawing, it always amazes me how many dimensions I missed. Gotta go back out there and do another 15 minutes of measuring.

Re: XM-708

Posted: Fri Aug 02, 2013 9:14 am
by Paladin
Just FYI, there is one of these on epay right now. Not mine, and no connection, just saw it. Its listed as an M37b1 dump truck.