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HomeAircraftHelicopterBlades and Night Flying › 78mm tail blades with 600mm main blades, would this work ?
03-24-2017 08:29 AM  20 months agoPost 1
joshreynolds777

rrApprentice

Willis, Tx

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I realize maybe this should be in beginners corner. But while I'm working on a night bird, I put some (what I think are) 600mm main night blades on my trex 550. (They are right about two inches, or 50mm longer than my 550 kbdd blades) (Although they do look very much like some 613mm blades I've seen on hobby king) With the stock tail blades on there, and an over kill 20 something degrees of pitch on the blades, and a little "down force" I was able to get the main and tail blades to touch on the bench. I have a spare set of 78mm blades for my trex500 I slapped on and there's plenty of clearance now. They're maybe a centimeter, 3/8" or so shorter than the 550's tail blades I took off. This is just for goofing around hovering a little, but I figure this is the best place to ask, but will this combination even work ? Or is the geometry just way off here ? Again, I don't even need to spool this thing up if you guys think it's a horrible idea, but do keep in mind it's just for giggles and a little test hovering around to see what the blades look like, maybe with the addition of a night canopy. The 550 is well set up with a beastx on there. 36 percent of positive gain on the gyro in the transmitter or an "F" on the scale showing light on the FBL unit.

Thanks in advance for the input guys

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03-24-2017 01:38 PM  20 months agoPost 2
Pistol Pete

rrProfessor

Seffner, FL

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For starters, blades are measured from the tip to bolt hole.

As you already figured out, had you not changed the tail blades you were setting yourself up for an unpleasant surprise.

Given you changed the tail blades, you have to increase your gain or your tail will wag. I would do this even before hovering it and also test during daylight hours.

Since you are only going to hover around to experience the pretty lights, do so cautiously specially when landing. Night landing is harder than you think.

Should you decide to keep them on (and chances are you will because night lights are cool), consider a 600 boom set up.

Your flight time will be greatly reduced given the larger blades.

For what its worth, not something you want to be doing in your front yard or with spectators.

Finally, have fun!

~~Enjoying the hobby one flight at a time~~

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03-24-2017 02:06 PM  20 months agoPost 3
RM3

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Killeen, Texas - USA

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and additional issue you may run into ( I did was when I went to larger main blades 640s to 693ss after stretching the tail ) I lost tail authority especially after dropping the Head speed. This was very noticable when flying sideways and very bad (tail blowing out) when backwards. o counter this effect to some extent I had to go to longer tail blades.

If your just sport flying, you should be OK, but take it easy and test during daylight... losing orientation at night is much easier to do.

showing a preference will only get you into trouble, 90% of everything is crap...

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03-24-2017 07:27 PM  20 months agoPost 4
joshreynolds777

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Willis, Tx

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Like I said I don't plan on even doing any serious forward flight with this set up.

But, I thought tail wag was from gain too high ? So your saying thegsun will now be too high with the smaller tail blades I suppose ?

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03-24-2017 07:27 PM  20 months agoPost 5
joshreynolds777

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Willis, Tx

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I want to add I'll be using head lights for landing and take off

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03-24-2017 07:51 PM  20 months agoPost 6
RM3

rrElite Veteran

Killeen, Texas - USA

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But, I thought tail wag was from gain too high ?
thats the usual culprit... but on many FBL controllers, like the GCY750 which I use, there are other settings that can result in wags like delay forward, feed forward, stop gain, etc.

just depends on what setup you have.

showing a preference will only get you into trouble, 90% of everything is crap...

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03-26-2017 12:07 AM  20 months agoPost 7
AirWolfRC

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42½ N, 83½ W

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Longer than stock main blades with shorter than stock tail blades is asking for problems.

More tail blade is always better for control, even over stock.

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03-26-2017 06:50 AM  20 months agoPost 8
joshreynolds777

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Willis, Tx

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Well, I gave her a try. And it worked out
Didn't make any adjustments. Flew great ! That 550 got really stable with those 613mm on it :-). Pretty fun. Just a little hovering around. So no fff to see if the gain needed to be adjusted.

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03-26-2017 12:54 PM  20 months agoPost 9
revmix

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NJ

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the 3D helis are so much overpowered that with half power reduction still works
less torque is enough for normal sport flying & the tail is sufficient for keeping the heli's heading (steady & no blow out)
larger blades with lower RPM the rotor-disc works with less torque than smaller blades with higher headspeed

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03-26-2017 02:16 PM  20 months agoPost 10
Four Stroker

rrElite Veteran

Atlanta

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Now that I am old, all I do is auto's. I put 550 tail blades (82mm) on my 600 just to keep them out of the grass. Can't tell the difference.

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03-26-2017 11:59 PM  20 months agoPost 11
AirWolfRC

rrProfessor

42½ N, 83½ W

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Sure - - everything works fine - - until you push the limits
- - then you find out what you lost in control-ability.

The only way to know for sure is to verify what your tail pitch is in flight. To do that, you can turn on your electronics on the ground without the main motor and measure the tail pitch with the sticks at normal flight position.

If your tail pitch is coming up to about 15º then you're at your limit in that direction.

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03-28-2017 07:49 AM  20 months agoPost 12
joshreynolds777

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Willis, Tx

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Like I said, Im not planning on this being a permanent fixture. But a big pitch back does freak me out a little. Its hard to see, or to be able to tell exactly how much clearance I have between the tail and main blades. It "looks" like Ive got a solid inch or two. But at a hard back pitch input, i worry I'll fall out of the air in a major way lol

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03-28-2017 03:33 PM  20 months agoPost 13
Ladymagic

rrKey Veteran

South Korea

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If you have to focus concern on how much clearance you have then that's probably a sign that you shouldn't mess with that setup at all.

One inch is not nearly enough clearance since you cannot account for stretching and flexing under load...it's probably much less than you realize.

General rule of thumb is to set clearance based on maximum degree of use. If clearance can be reasonably maintained under extreme circumstances then the setup will more than likely be good under normal conditions. Otherwise change the setup.

The "everything seems fine so far" mindset could come back and bite you hard if you are not careful. I've seen it happen. Sometimes it's funny; other times, it's down right scary.

Please be mindful....it only needs to go wrong once and I promise you, you'll never want to use that setup ever again. I bet it wouldn't take more than a slight bump on a landing to have them touch and explode bits of blade in every direction.

Just my two cents.

Mellisa

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03-28-2017 05:36 PM  20 months agoPost 14
joshreynolds777

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Willis, Tx

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Holy cow !! I've never talked to a woman in this hobby. That is awesome !!! I swear I'm not being sexist. But that's just really cool. I just figured you guys were like unicorns, thought I'd never come across one. !!!
Tell you what, I'll take your advice and rid the setup. That's an excellent point. A hard "bump" landing, yep, that could do it !

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03-28-2017 09:01 PM  20 months agoPost 15
Ladymagic

rrKey Veteran

South Korea

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Yep. Not a unicorn, but I am a heli pilot and enjoy the challenge just as you.

I have been around for a while just been quiet here lately because there's not a lot going on lately. I still love to help when I can though.

I give you that warning out of experience with other pilots who did the same thing. It seems to go right a million times but it only needs to go wrong once and it'll change your soul first time you hear the sound of your blades disintegrating at 2000rpm 15ft in front of you.....you can't get away fast enough.

Just sayin my friend.

Mellisa

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03-28-2017 09:02 PM  20 months agoPost 16
AirWolfRC

rrProfessor

42½ N, 83½ W

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If you can take a rearward blade directly over the tail boom and push the tip down (with some force) and it intersects the tail blade arc, you have a problem! - - - Don't fly that way.

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03-29-2017 12:57 AM  20 months agoPost 17
ant_mb

rrElite Veteran

United States

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Us women in the hobby aren't unicorns! Blade sizes are in the manual as well, if you want to push the limits then do so, but asking on a board is like pushing your luck. Do so if you want, but accept the consequences!

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