View Single Post
Old 12-30-2013, 04:38 AM   #1
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 1,551
Thanked 167 Times in 159 Posts
iTrader: (0)
Friends: (1)
Default Dynam Me262 mods

You will see that my model has been around a while... Lost track of the number of flights and it bounced off a fire hydrant once. (straightened the wheels and went back to flying)

Stock as shipped, these have been clocked approaching 110mph. (with the bad CG) Moving the CG reduces tail downforce which also unloads the wing (and you don't have "dead lead" ballast) so they get a LITTLE faster. (maybe 112mph... haven't put a pitot tube in yet)

I got this plane to learn about the habits of the Me262 since I am building a 107 inch span one. The foamy paid for itself the first time I attempted hammering the throttle from a standstill, pointing out one of the worst habits the plane has... High power and no airspeed will flip the airplane.

#1: This plane needs the CG pushed BACK. Currently I use a spacer to keep me from pushing the battery all the way up to the front. I have it set at appx 1/3 inch back from the foam stiffeners/battery guide at the front of the fuselage. This is just about perfect when using 4S 4000mah.
CG as recommended in the manual is just WRONG and requires up to 8 oz lead to be added in the nose-gear wheel well.
OEM CG is to combat the plane's bad habit of the thrustline overpowering elevator at low airspeed with full throttle. Its better to just learn to manage the throttle, since the plane flies much better with the correct CG.


#2: Adding cooling airflow for the battery and ESCs.
Use a 1/2 inch dia brass tube, with sharpened end, to drill out the 4 gun ports as ram-air scoops.
(Mine are re-painted already)
Cut at an angle under the forward hatch magnets to allow airflow beside the battery. I also put in some foam tape to lift the battery so some air can go below it.
Then behind the wing I chopped a good sized air exit hole.
Further... I CAd the ESCs edge to edge with each other and chopped some windows in the heat shrink so the air flowing in the fuselage cools them better.
I can fly in 110F weather without having to worry about a thermal shutdown of the ESCs.

#3: Final mod is not complete and untested.
Set at the aft CG I have been flying with significant down elevator trim due to the keyed horizontal stab setting + downward 'lifting" tailplane airfoil effectively giving up elevator. This was needed to make up for the excessively forward CG as recommended in the instructions.
I broke the glue joints free, removing the horizontal stab and am in the process of converting the plane to have SCALE in-flight adjustable horizontal tailplane incidence.
(this will mess with my CG a little... I probably need to change my spacer)
I found that a Hitec 5245MG is a perfect fit for my desired servo location. This should be plenty of power for the purpose.
Carefully split open the glue seam on the upper back of the fuselage to route the servo wire and cut a relief hole in the fin well for the wire.
Re-glue the seam after running the wire.
Cut out the raised foam in the fin well (the bit that goes between the "tabs" on the fin is the same size as the servo) and relieve the fuselage side for the servo arm.
When the fin is screwed down the servo is secure
Install ply plates as pivot bearings for the horizontal stab's CF tube.
Final part is installing the front wire which the servo will act on to move the horizontal stab. This is pretty standard stuff for setting up a "flying stab" where the elevator is the whole horizontal stab.
The reasons for this mod are:
.... The horizontal was starting to come loose anyway
.... Experiment in how sensitive this will be on my larger model.


Attached Thumbnails
Click image for larger version

Name:	Me262 Foam tail mod 005a.jpg
Views:	102
Size:	106.6 KB
ID:	172675
Click image for larger version

Name:	Me262 Foam tail mod 006a.jpg
Views:	87
Size:	74.7 KB
ID:	172676
Click image for larger version

Name:	Me262 Foam tail mod 007a.jpg
Views:	105
Size:	77.4 KB
ID:	172677
Click image for larger version

Name:	Me262 Foam tail mod 002a.jpg
Views:	91
Size:	97.6 KB
ID:	172678
Click image for larger version

Name:	Me262 Foam tail mod 003a.jpg
Views:	89
Size:	114.6 KB
ID:	172679
Click image for larger version

Name:	Me262 Foam tail mod 008a.jpg
Views:	87
Size:	100.3 KB
ID:	172680
fhhuber is offline  
  Reply With Quote
 
Page generated in 0.32708 seconds with 24 queries