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CP Pro/DX7 power problem??

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E-Flite Helicopters Discuss the line of E-Flite mini and micro helis including the Blade CP, CP Pro, Blade CX, etc

CP Pro/DX7 power problem??

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Old 06-24-2007 | 03:43 PM
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Default CP Pro/DX7 power problem??

After a few modifications I seem to have lost some of my power. I added Super Skids, changed out the main shaft and gear to the micro heli shaft - gear - autorotation bearing. I have also changed the tx/rx to the DX7 and AR6000. Following the radio and main shaft swap I had to mechanically re-level the the swash plate and get all servos back to "0" position when the radio sticks are at mid-stick position. I can get +/- 10 degrees in pitch, however, since I am learning I only fly in normal mode with a pitch travel from about -1 to +10.

I have no problem at all getting the Blade into hover at just above half stick as it should, what I don't seem to get is the rapid increase in power/lift as I did on the stock radio. This is fine for right now since the Blade is very tame. Down the road though I will want the extra power and want to have access to it. When I move the throttle up the in a very rapid move the heli makes a controlled climb unlike the "jump" it used to make. I am sure the Super Skids have some effect, but I don't think it would hold it back as much as I am experiencing. Also, as I get the throttle within 2-3 clicks of max, there is a lowering of the sound the motor makes - similar to the sound a draining battery might make. When I back off, it returns to normal. It just doesn't sound like I am getting the same head speed I was before the radio swap.

Any ideas??
Old 06-24-2007 | 04:07 PM
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Default RE: CP Pro/DX7 power problem??

Your super skids are definitely adding to the weight, and perhaps contributing to your head bogging problem. Maybe the autorotation bearing, too. What are your pitch and throttle curves? Obviously you aren't getting enough head speed.

I suspect your throttle curve should look something like 0-30-65-85-100. Pitch something like 40-65-83-93-100. I don't actually have a CP with a DX7 with which to test them. When you verify these with a pitch gauge, are the measured pitches correct?
Old 06-24-2007 | 05:07 PM
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Default RE: CP Pro/DX7 power problem??

Used a gauge for the pitch to verify and I am prtty much on the money for the pitch settings. My pitch curve is 48-56-62-72-77 It was 48-65-75-90-100. I lowered it to see if it would make a difference with a lower pitch. It did not. My throttle curve is 0-44-65-85-100. Main rotor speed sounds fine until the last few clicks in throttle and I also noticed it when applying a semi quick cyclic command. Maybe it does have trouble overcoming the Super Skid weight, but I seem to remember prior to the skid upgrade it was doing the same thing on the old skids. Maybe I will have to "unmodify" the skids to zero in on the problem. I am waiting for the DD tail to come in and the last thing I want is to add to the weight problem. I think I would take the DD mod over the super skid based on the short life of single tail motors.

As far as pitch goes, I think the manual says you can go from -12 to +12 and I am at -10 and +10. I guess there is just more tinkering to be done. It really does behave well from about 70 to 90 percent on throttle though.
Old 06-24-2007 | 07:02 PM
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Default RE: CP Pro/DX7 power problem??

about the +10 vs the +12, make sure your servo links are all the way to the outside on the servo horn. I put mine in the center hole all the way to the outside and I get the full +12. If that's not it, that 's real confusing to me unless your radio settings of max pitch at 77% is doing that.

About the super skids, they are the problem. The super skids add a ton of weight
http://www.heli-max.net/mediawiki/in...for_the_CP/Pro

29g total. Believe me, I know =P I've been doing alot of testing as far as weight on this heli lately, and I am flying the dual tail which adds 13g and without the canopy which subracts 11.5g, so it's basically stock weight, but with a cg that is shifted more towards the back. I can't believe the difference in flight going from my stock 800 pack to my 1250mAh packs. The heli just has no climbout power. The difference in weight is 66.5g for the stock pack, and 102g for the 1250mAh pack, so that's only 35.5g difference, or just a scosh more than the super skids.

You can probably also make up for the weight difference if you go with a brushless setup. I saw a vid of a guy's who's AUW was right around 450g with the park 370 4100kv, and he could fly failry resposively even at that hudge weight. The AUW on my heli is 319g wwith everything except the canopy. The stock weight is supposedly 298g, but I don't know if I believe that one.
Old 06-24-2007 | 07:35 PM
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Default RE: CP Pro/DX7 power problem??

Thanks mrasmm. Good info to know. I think I might go back to the stock skids just to verify these thoughts. Once done, I will post again. I can say that for a newbie (like me), the problem I am having is actually a good one in that the Blade is very tame and very stable. I just know that down the road I will want that power back.

I am also trying to knock out one last bit of vibration that appears to be head related. I put the new main shaft in (hard steel) and with the blades off there is a barely noticable wobble in the head. Not sure if it is weight/balance related or out of whack. With the blades on it seems to exagerate it even more. Easy to see the wobble with the autorotate.. bearing and the head spinning down. I will also need to get a good blade balancer and be done with the crude method. Did someone say this was an expensive hobby????
Old 06-24-2007 | 08:07 PM
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Default RE: CP Pro/DX7 power problem??

hehe yup, that it is, and you're welcome

about the balancer, I personally don't bother with one. The holes in these blades are so small that most balancers will not work.

What I do is disconnect the motor from the main gear, you can do this by removing the motor or loosening the collar and sliding the gear down. Start with the blades off and the power off and the heli on it's side and the main shaft perfectly level with the ground (acually gravity, but you get the idea), make sure the swash is level, that the gear wont bind on the motor pinion, and give the heli a whirl. whichever paddle stops on the bottom side is heavier, so make that paddle closer to the head by sliding the fly bar about 1/16" of an inch. Keep going until when you give it a whirl the flybar comes up level. repeat with the main blades, except by using tape. You can also balance the cg with the tape on the blades, and if you want those instructions, PM me with your e-mail and I'll be glad to send them on over =)
Old 06-24-2007 | 10:02 PM
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Default RE: CP Pro/DX7 power problem??

Yeah I have my Throttle on "normal" set to 0/35/65/85/95/100. It helps having a steep curve but then smoothing out mid to late stick. If you are worried about headspeed put it to midstick and flip to idle, just to see the difference, if you set it right the half stick should be half throttle. If you want to test, put stunt mode 1 throttle at 100% at all points. That is the max this controller will spin the blades. So at midstick you should be 0 pitch and 100% throttle (with my mod from above). How does what your seeing compare, speedwise?

Make sure you know what you are doing or remove the blades before playing too much or you will end up with a broke heli.

DY
Old 06-24-2007 | 10:18 PM
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Default RE: CP Pro/DX7 power problem??

mrasmm - Thanks again for more tips. I will give that a try tomorrow. That should fix the vibration I hope.

DY - Right now the idle up curves 1 and 2 on the DX7 are not fully programmed yet. I have been doing the mods mentioned above, plus getting the swash programmed with the radio took a little longer and then I had to adjust the mechanical links with the new radio setup. What I can probably do fairly easy is bench swap the radio back on temp basis - minus rudder (every minute in the tail motor is important) and crank up the throttle while holding the heli - blades facing away of course - to see if I get the same kind response I get using the DX7.

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