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Raptor E720 › E720; Why isnt there more buzz about it????
12-15-2011 04:08 PM  5 years agoPost 41
rexxigpilot

rrProfessor

Florida

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Anytime you translate circular motion like that of a servo output shaft and arm/wheel to linear motion, as in the linkages, you are introducing non-linearities and potential interactions. The linear motion is approximating a sine wave. Bellcranks introduce an additional translation and added non-linearities or potential interactions. With a bellcrank, the longer the output arm in relation to the input arm the less rotation is needed to provide the same ammount of linear output. This can reduce the non-linearity if it results in less rotation if the bellcrank, but it will not totally eliminate it. So bellcranks will always have more interaction than a direct servo to swash system. provided the same ammount of servo resolution (rotation) is used.

Perhaps some rack and pinion system could be devised to translate the circular motion to linear. Then the non-linearities could be eliminated.

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12-15-2011 06:08 PM  5 years agoPost 42
gwright

rrVeteran

Champaign Il

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quote "So bellcranks will always have more interaction than a direct servo to swash system. provided the same ammount of servo resolution (rotation) is used."

I don't think that is correct. Same amount of rotary motion from the servo, reduced to less rotary but with a longer arm via a bellcrank,.. is more linear. Take a 1 inch servo arm moving 45 degrees, compared to a 2 inch arm moving 22.5 degrees with the servo attached to it at a 2 to 1 ratio. Servo movement the same, force at the ball the same (double lever, halve the ratio), so you end up with the same amount of movement but less of an arc, thus less chance for interactions due to differential movement.

Rack and pinion,.. now that would be the holy grail!

Gary Wright

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12-15-2011 09:57 PM  5 years agoPost 43
rexxigpilot

rrProfessor

Florida

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Sorry Gary, the effect is serial. Any bellcrank use makes it worse.

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12-16-2011 12:02 AM  5 years agoPost 44
synodontis

rrKey Veteran

United Kingdom

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It is correct that shorter bellcranks introduce more interaction when they move away from center
that's a totally nonsense statement.

whether it go through bells cranks or direction has no bearing on the issue. the issue is purely software and how it deals with the CCPM setup. where the bell crank is you can place the servo arm and you would be left with the same issue.

smaller bell cranks do NOT introduce MORE interaction. smaller bell cranks limit the collective range of the swash, also limits it's cyclic throw range as well. this should be obvious. It's up to the CCPM software as to how well it implements swash control given what its got to deal with. Talking about "interaction" is nonsensical in this regard unless we factor in the discrete steps that the servos have to move at, in which case smaller bell cranks will give LESS interaction, but also LESS range, because the steps are finer the CCPM software can moved to a finer grain level than if we have larger cranks to swing (throws get magnified).

there is NO point in making smaller bell cranks move to the same collective range on the swash as larger bell cranks because, as you know, they have to swing more which in effect gets to their extremes and goes out for range for certain positions, not to mention the speed issues involved. in this sense I agree with with you, but not in the interaction part. ALL CCPM have interaction because of the inherent nature of CCPM, There is absolutely NO SUCH THING AS GEOMETRICALLY PERFECT CCPM, it's not possible, the geometrical implementation of CCPM and the discrete servo steps prevents it.

and what's this talk about "linear" servos anyway? it's mainly talked of by ignorant or clueless people. If you fix the collective and move the cyclics the balls of the swash trace a sphere!!!

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12-16-2011 12:05 AM  5 years agoPost 45
synodontis

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United Kingdom

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So bellcranks will always have more interaction than a direct servo to swash system. provided the same ammount of servo resolution (rotation) is used.
no, it will not.

think about it.

what does the bell crank do apart from being a transfer point? neglecting slop on linkages and play on the cranks and/or arm flex there should be no unwanted contribution to the control loop.

if you think bell cranks add more interaction imagine a servo where it is swing the same sized crank as noted above.

what you talk is nonsense.

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12-16-2011 05:35 PM  5 years agoPost 46
Zaaaguy72

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MN

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I respect both Gary and Rexx's view point, they are both very knowledgeable pilots and good guys. Still dont know the definite answer though!

Team Sanjel!

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12-16-2011 06:08 PM  5 years agoPost 47
rexxigpilot

rrProfessor

Florida

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Thanks Zaaaguy72. I was not even going to respond to his posts. Most of us know that a "sphere" is a three dimensional structure and a servo arm does not follow that path (notice he edited his post from servo arms to swash balls?). This is still wrong as the path the swash balls would follow is an arc. At least he changed the part about being an idiot to ignorant.

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12-16-2011 06:36 PM  5 years agoPost 48
synodontis

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United Kingdom

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why are you lot so fixed on wanting direct servo linkages?

why? I don't get this.
Most of us know that a "sphere" is a three dimensional structure and a servo arm does not follow that path (notice he edited his post from servo arms to swash balls?). This is still wrong as the path the swash balls would follow is an arc. At least he changed the part about being an idiot to ignorant.
FIX the collective (i.e. do not move it), then play with the cyclics. The balls of the swash will trace the surface of a sphere, centred at swash centre. The front swash ball will move in a plane, agreed, but two backs won't, because aileron inputs will tilt them. A sphere (or rather parts of it) will be traced.

I didn't edit anything, but only too glad to acknowledge corrections if need be.

[actually I tell a lie: it's not possible to trace a sphere because of the interaction of CCPM!!! You can try this out on your helis yourselves. fix the collective and move the cyclics around and note if the center of the swash is moving up and down, it will because of interaction. Only perfect mechanical mixing helis will not have this (kalt etc . . )]

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12-19-2011 04:33 AM  5 years agoPost 49
MADGUNS

rrApprentice

Kadena AB Japan (Okinawa)

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This helicopter is awesome.

I'd like to pick one up but for right now with Christmas its a no go.

But if you want one now is the time to snap one up

Deep discount and free shipping, you cant go wrong with that.
http://www.towerhobbies.com/

Happiness is a belt fed weapon

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12-19-2011 04:02 PM  5 years agoPost 50
scott s.

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Orange, Ca.

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i don`t see any discount

It`s still just shy of $1000, same as before

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12-19-2011 04:06 PM  5 years agoPost 51
Heli 770

rrProfessor

USA.

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You won't see the discount until it's totaled.

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12-19-2011 04:28 PM  5 years agoPost 52
rexxigpilot

rrProfessor

Florida

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You have to use the TH discount codes! They are shown on the homepage and you get codes emailed to you if you are a TH supersaver club member.

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12-19-2011 07:05 PM  5 years agoPost 53
Zaaaguy72

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MN

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I am so tempted!!! My logic tells me "no," but the little devil in me say "order it right now!!!!"

Team Sanjel!

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12-19-2011 09:41 PM  5 years agoPost 54
Turbo Dave

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Sydney,Australia

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I own one and also borninthesky has one too.

His machine is an animal! Looks completely weightless in the air and has commented that after owning quite a few 90's in the past it's the best 90's he has owned. Next time he is out with it I will get some video of it.

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12-22-2011 08:35 PM  5 years agoPost 55
toto

rrApprentice

Argentina

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I fly the E720 and the nitro version too.
The only thing that I don´t like is the metal tail pushrod.
Both are really great machines
For some people "raptor" is a bad word, but for me, TT are great helis with very good relation between quality vs cost.
Sorry for my english.

Feliz navidad!!

Best regards,

Toto

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12-27-2011 04:19 AM  5 years agoPost 56
GM1

rrElite Veteran

Tallahassee, Florida US

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E720

I have an E720 after watching Wayne Mann fly one at the World Champs in Italy this Summer. Unfortunately, Wayne only had the models flying for about three weeks before he got there and while he made the finals, he would be the first to admit he would have been better with more time.
In my case, I took my G4 to contest with only 25 flights on it and managed to squeek out a win in F3C. Gary was there and can vouch for my like of the model. At the Orlando Heli Blowout, I watched Gary fly his flybarless G4 model at around 1600rpm and 3D the snot out of it FOR 12 MINUTES. It was amazing to watch, having more than enough power to do anything.
As many of you know, I spent a huge amount of time getting the mechanical set up on a model as good as I can. My X-Cells took weeks to get right. My Hirobos took about 50-60 flights. The G4 E720 was good after 16 flights and I have made no set up changes since then other than fine tuning expo and dual rates, no mechanical changes. I do not like the stock red canopy as it is very difficult to see at any distance but I put some neon yellow trim monokote flashes on the red canopy and it was much better to see. Since then, I got the yellow canopy and prefer that. So far, I have seen no wear issues on the model and my flying is getting better as I learn the model.
Gordie

On a dog sled team, if you're not the lead dog, the view never changes.

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01-01-2012 12:05 AM  5 years agoPost 57
Rob43

rrKey Veteran

Midland, MI USA

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As my sig indicates, I have a 7HV. It's a wonderful heli...not that I am a credible source of review...Hahah. I also really like this new TT bird. I read the review in RC HELI PILOT magazine, and loved some of the details shown (although I had to laugh out loud in the 6HV review that they found that since Compass doesn't offer other pinion gears they had to stick with a 10t for the review...how silly!), such as 15mm shaft, thick main gear, adjustable servo arms. A nice alternative to the others. Radically different from my 7HV. I've never been able to detect interaction on my 7HV with it's shorter links and direct to swash control. It's wonderfully stable close to center stick, just as I bet this e720 is. Indeed the e720 does cost a bit more to purchase. But it does appear to have a few items that are worthy. An all metal tail for one. Many question the plastic tail of the Compass. Frankly, plastic tails don't stand a chance, we all insist on CNC. It's just like a repaired hood on your car. No dealer will repair a hood. You stare at it all the time, and think, "it's not right". Same with a plastic tail. I believe Compass will be forced to provide a metal tail in the end, but that's just me. The plastic tail flies fine. I think the e720 is about selection and when someone wants something that isn't the same as the others. It's a wonderfully nice alternative. When it costs about $3K USD to put a 700 in the air, I find it a little amusing that people scoff at $100 premium for the heli. That's just 3% folks. Just my perspective.

Rob

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01-01-2012 11:43 PM  5 years agoPost 58
helicraze

rrElite Veteran

Victoria - Australia

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agree with your points rob

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01-04-2012 01:27 PM  5 years agoPost 59
Individual1

rrApprentice

Oregon

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E720 Weight

Rob.. How much does your 7HV weigh ready to fly with 5000mah Lipos? The E720 with Flightpower 50C 5000's which weigh 850g vice Thunder Powers 65C 5000's 802g comes in at 12.35 lbs.

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01-09-2012 06:07 PM  5 years agoPost 60
hobby_man

rrNovice

MPLS, MN

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Tower Hobbies

I have been shopping at Tower hobbies for 25 years, and I will for the next 25 years.

I stared with Heli Max heli's because that's what tower sold.

great return service at Tower, NEVER had an issue with hobbies services and I have a Traxxas Spartan boat, that has spent more time in the shop than on the lake.

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Scorpion Power Scorpion Power
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Raptor E720 › E720; Why isnt there more buzz about it????
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