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View Full Version : Hobby Lobby Mig-21 Flight


Kosh
03-07-2009, 09:11 PM
This EPP foam Mig will 9 times out of 10 roll over on it back just after launch so you really have to be fast to correct it. Once in the air and trimmed out it handles well with a outstanding roll rate second to none. It can be flown slow but likes speed and responds fast to your inputs.

The plane is setup with a pair of 9gr. servos, Cheap $6.95 1800kv outrunner spinning a APC 7x6 prop. A 20 amp ESC with a 25C Rhino 1350 3 cell top off the power giving the package 10 minutes of flight. :cool:

http://www.cascadeap.com/Mig21.wmv 22.6MB (Better Quality)

http://www.vimeo.com/3510338

max2112
03-07-2009, 11:01 PM
Well done, Kosh!
I definitely see what you mean about it wanting to roll over on launch.

I loved the high alpha stuff at the end.

Two thumbs up!:tc:

Kosh
03-08-2009, 01:15 AM
Thanks John, Just letting others know what they may be in for on this.

spudandcat
03-09-2009, 11:26 AM
Nice one Kosh , i had a 3000 kv blue wonder in mine with a 25A esc and a 4 x 4, that got rid of torque roll probs ! it flew really well and quite fast . only problem was keeping the esc and batt cool. sealed inside the fuse they just got to hot ! tried to get some air in thru the nose cone but it wasn't enough. i put the motor and esc in my msw , they stay nice and cool in that! i'll put a lower kv motor in it and run a 6 x 4 so it doesn't get quite as hot , one day. And here's a picture!
seeyas later
spud

7car7
02-15-2010, 05:26 PM
Hey, finally found something on this plane! I bought one of these during the Thanksgiving sale, and built it over Christmas.

I was concerned about the lack of airflow, so I added some NACA ducts in the front, and exit vents in the rear. Must be working, because the battery stays at a nice temp.

I've had my share of headaches with this plane. Like you Kosh, I've experienced the dreaded violent roll to the left on launch. I'm not sure if I've ever had a successful flight when self launching. I even mixed rudder with aileron so I could give it some right aileron with my left thumb.
What I have not tried yet, and will next flight, is launch with the left hand, so my right is already on the ailerons in the normal way.

It's had it's share of crashes, but only during launch. Lot's of repairs.
This is the first plane of this type that I've flown, I've only flown electric bi-planes - huge departure.

I was experiencing some odd flight once it was up in the air. Couldn't tell if it was a CG issue or what. Every test I could think of (throttle off, upside down etc..) told me the CG was fine, but the plane was eratic. It would be flying along, and then just shoot up or down all on it's own.
I came to the conclusion that it was just extremely aerodynamically dirty with it's thick leading and trailing edges. I tapered the leading and trailing edges of the elevator and vert fin to look like a knife. I added some thin carbon flat strips just aft of the leading edge of the wing, top and bottom. (they had a slight warp to them)
Leading edge was rounded over, and the trailing edge (ailerons) were knife edged too.
What a HUGE difference. It's like it's on rails now. Goes where you point it, and it will not deviate at all.

I've had a couple different nose cones on it. Original one lasted only first attempt. Second one I made from white foam coated with epoxy, and it exploded. Third times a charm. Made it from card stock paper, and filled it with Gorilla glue. (lined with glue, sprayed with water, let dry, added more glue, more water, about 3 times until it was mostly filled with foam.)
This version has stood up to a few crashes that actually broke the fuse just forward of the cockpit.

So, since the fuse broke, (about 3 or 4 times) I added 3 strips of carbon to the fuse. One on top, (from nose, going into the bottom of windshield). Other two at 4 and 8 o'clock looking at nose.

For the battery I of course cut a rectangle hole like everyone else I'm sure, but made a cover from a contact lense cleaning solution bottle. Hinged at the front with hinge tape (glued on with CA), and tiny rare earth magnets at the rear. A velcro strap glued to the inside of the battery slot keeps the battery from flying out. (been there - was pretty wild - blew out at about 100 feet up)

So, after all this, this plane is a blast to fly, it's very addictive. Just wish it wasn't so hard to launch. It will fly slow, and it's a lot of fun to just cruise around, then punch the throttle. Unlike my bi-planes, you REALLY see the difference between 1/2 and full throttle.

btw, I'm using the little screamer motor that was recomended, and a Graupner 5x4 CAM prop. Tried a 5x5, but it torqued over more. The 5x4 is not much better, but it works.

Mine is camo. Was hoping for the red, but that's not what shipped.

Kosh
02-15-2010, 06:39 PM
Here's what I found that helps me launch mine. Think about it as throwing a football and letting it roll off your fingertip with a lite right spiral spin. Make sure your hand always follow through so you don't get bit by the prop.

Good luck and never give up.

7car7
02-15-2010, 07:18 PM
Noticed something from the photos of your plane - the red one seems to have better leading and trailing edges. Mine were completely squared off.