Dihedral, ailerons and thrust angle

[900dukess]

Help please
I have added ailerons to my SC, I also added a carbon rod into the wing and removed most of the dihedral, the wing is almost flat. I tried a test flight and I had no lift, I used the elevator and it stalled. I previously fitted a 450 motor from a parkzone Trojan and it was awesome. I double checked the CG and it's perfect. I looked at the downward thrust angle, so I added some washers between the firewall and motor mount, now the prop has no downward thrust angle. I went for another test flight, it fixed the stalling problem, but I have lost a lot of speed. Questions what is the stock downward thrust angle? Has removing the dihedral caused a significant loss of lift? Any other suggestons/ help would be appreciated

[ginginho]

Did you seal the gaps created after you added ailerons? If these are quite wide this will effect the lift produced by the wing as it allows air to escape between the surfaces. You only need to seal on one surface so some tape along the hinge line is good enough.

Removing dihedral will not effect lift as long as the wing still has the same angle of incidence. It will however remove the self-righting characteristics so it will be more of a "hand-ons" flyer.
The thrust angle doesn't really effect lift. By having the motor pointing down a tad removes the tendency to pitch up when throttle is applied.

I'd suspect that the park 450 with the right prop will make a SC go pretty much vertical at WOT, which would suggest that it wouldn't stall in level flight. When you stalled did you have any/all throttle applied? What sort of maneuver were you doing when it stalled?

You've stated that it was "awesome" before and now have lost a lot of speed. This would suggest either that you are down on power since doing this mod or the airframe has become considerably more draggy.
Check your motor/prop and make sure those are as before and make sure your wing is attached to the airframe correctly (i.e. not at a different angle or back/forward).

[belem]

Sorry to ask the obvious...but is your prop on backwards? Ailerons and dihedral removal shouldn't cause any of those problems.

[900dukess]

Thanks for the tips

You are right, it used to go vertical under WOT (which was great, it used to ROG in about 2 metres or less), before I removed the dihedral and fitted ailerons.

I went for another test flight this morning, this time in a larger field, and it went OK, still a little disappointed with the vertical performance.

I have minimal gap between the aileron and wing ( I used CA hinges).

I am starting to think that my motor is starting to die, or the ESC is playing up, cause I noticed varying performance during the test flights. I suppose it also could be my batteries playing up (They are about 3 months old, and had a pretty hard life).

I might have to invest in a watt meter to check the motor/esc?

Unless you guys have any more sugestions?

[ginginho]

Of the three options mentinoed, I'd be suspicious of your batteries if you've been treating them tough. If you have ever over discharged them, left them fully charged for an extended period and they are driven hard when WOT is applied then they may have started to deteriorate.

Get a wattmeter, you will not regret it. You will be able to check your current draw and check the voltage drop of your packs under load which will help confirm if your packs are on the way out. It'll be invaluable in the future as and when you move onto other airframes.

It's worth taping over the hinge gap anyway, any gap means loss of lift.
You may be surprised how much you lost (and regained) once you've done it.

[flydiver]

Yep, probably a dying lipo. New fliers tend to ruin a few before they figure them out.
The 450 will pull WAY more amps and if you over propped it then the battery likely could not keep up.
You prop for the MOTOR, not the plane.
That motor can easily do 20A on the Trojan prop. The Trojan 1800 can keep up with that. If you used the 1300 Cub lipo that alone was too much draw (vertical---right?) Flogged that lipo.
If you put the 10x8 prop on you were WAY over the top, both for the lipo and for the motor.

Brushless motors don't merely die from use. They get broken in crashes or damaged from overheating (demagnatized or burn wires) from over propping.
OTOH, lipos can be damaged a good number of ways.

[900dukess]

Ok, an update
I just returned from another test flight, I noticed one of lipo was puffed up, so I assume it's stuffed. Going to invest in some new lipos, better go for some 2200 mah.
I tried some of my other 1500 lipos and it is ok, still not as much lift before mods.
It flys and handles almost the same as my mustang p51, which I am just adding some landing gear to.
Can anybody suggest some good brand of lipos, I have some rhinos for my mustang and they seem ok

[900dukess]

Ok, I finally got around to finding the problem.
Well it ended up being the Parzzone brushless motor.
The front of the motor which holds the front bearing had cracked (must have been from previous crash when I lost it!!!)
The parkzone motor front bearing mount is held on to the motor shaft by two 3 mm grub screws, well with the front part cracked it was allowing the outer case to move forward, and thus losing motor power. I fixed it by turning up a little alloy collar on my lathe, and fitted it.Now all good. Vertical climbs on wot.

I must admit though, I almost prefer my SC prior to the upgrade to ailerons, it was so much easier to fly before hand, I liked before how it would self centre all the time. Maybe I am just a crap RC pilot!!!!

I have orderded another wing to return my SC to stock for those times I just want a nice easy casual flight.

Has anybody fitted ailerons without removing the dihedral? If so did they still work?

[SCC]

Feb 7, 2010 6:53:23 GMT 1 900dukess said:

I almost prefer my SC prior to the upgrade to ailerons,

Has anybody fitted ailerons without removing the dihedral? If so did they still work?

Hi Duke.
I did the aileron upgrade without removing dihedral and they do work OK. But like yourself I prefered flying my SC with rudder. So I taped up the ailerons and put the rudder over to the right stick again.

[belem]

I left dihedral in mine as well. At first I considered moving back to stock but got used to the change after a bit and haven't used my original wing at all.