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.
Finished the linkage
The wire connecting the stabs at the front is secured with both screwed-on plastic straps and glued in place since it prevents the horizontal stabs from coming off the CF tube. There are clear screw straps on the top of the stab also since the foam won't hold a screw.
Looking forward to seeing the rest of the mods:) I put mine away some time back as it was too fragile for my flying/landing conditions. If I get around to seriously reinforcing the nacelles with heat shrunk plastic cases, it might be a goer once again. Handlaunching required a bit of a headwind, but it is a fair bit lighter than stock, with no undercarriage, rudder servos and linkages. It flew rather well for what it is, but I am still undecided about the project as a whole. Great to see you are having a good run out of yours:D
Ever since I got the 262 its been the plane I have flown the most.
I have to periodically straighten the LG struts but I fly off a decent paved runway.
The main gear did not come with set screws to hold the struts in place. They were just held in by friction. Not sure if that is typical or they left the screws out on mine.
I've also had the nosewheel steering linkage come loose. Just had to snug the nut back down and its fine.
Pretty slim complaint list really.
In-flight adjustable stab incidence is all set and ready for test flight. I adjusted it to allow +/- 7 deg from the factory set incidence.
I expect that to have the elevator straight with the horiz stab that i will be flying at +3 to 4 deg vs original at high speed setting. (where I trim this airplane normally)
I may eventually mix the stab to the elevator in the computer TX. We'll see how this works out with it on a dial. Initial takeoff I plan to have it set + 3 with elevator straight in alignment with the stab. Last flight's (before this mod) trim had the elevator 7 deg down.
I popped the block out so I can push the battery forward... I need to compensate for the weight added to the tail.
Finally got around to flying it with the adjustable stab. I didn't give it enough travel and it still has a slight down elevator trim with the LE of the stab as far up as it goes. But the adjustable stab does work. I can trim for level flight and loop on just the adjustable stab.
A little more carving to open the slot and an adjustment of the ATV will take care of that.
Overall its a successful mod.
The weight in the tail requires 4S 5000 mah to be as far forward as possible. 4S 4000 now have the CG too far aft.
Looks like I need to carve the fuselage foam a bit to let the 4000's slide forward more since my 5000's are getting old and are not giving the performance they used to.
I seem to get 3 1/2 to 4 years of use from a SkyLiPo (Nitroplanes.com) pack regardless of how many charges.
Doing a pre-flight for this weekend, I noted the servos starting to fall out of the wings, so I went over the whole airplane.
I found a trailing link (not scale) aluminum strut nose-wheel retract at Nitroplanes and near-scale all-aluminum retracts for the mains at Hobby King. It looks nicer with these installed and they operate slower than the originals which is appropriate for the full scale aircraft's slow retract cycle speed.
I also altered the movement range of the in-flight adjustable stab since I had it at the + incidence (forces nose down) limit all the time and was still using some down trim at high power.
I've still been using slight up trim for landing approach. In power-off dive tests the plane holds a 45 deg dive from close to stall all the way down when trimmed for landing, so I know I'm very close to correct stab angle and CG.
I plan to mix the stab to the throttle and disable the TX's knob when I get the relationship figured out. More throttle forces the nose up so it needs pitch trim mixed to throttle.
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