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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Virtual Flybar - what would you like to have?
11-24-2006 11:15 AM  11 years agoPost 1
Colin Mill

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England

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Following on from the Virtual flybar thread I would very much like the opinions of potential customers for such a system.

We are currently testing in almost final form an on-board CCPM mixer and we have several pilots assessing the use of this in conjunction with two SL720 gyros. We have been encouraged down this route by promising results of tests of a pair of SL720 gyros in a non-CCPM flybarless machine. Of course the gyro control needs to be rather different in cyclic applications to that used on the tail but the adjustability of the internal settings of the 720 means we have not had to do any changes to the core code of the gyros.

My initial desire is to produce an e-flybar system in a modular form - as separate units – mixer and two gyros. While I agree that this is not the most elegant solution I think it has some big advantages:-

Reduced development time/cost – most of the development work is already done! We have the mixer in advanced prototype form and the gyros are current production items.

The mixer is applicable to any CCPM helicopter with or without flybar and, because it can offer a high quality of mixing, will have far higher volumes of sales than something designed only for the e-flybar system and this will reduce the unit price. Also, the separate gyros are also applicable (with a simple change in the internal settings) to tail use with the volume sales advantage mentioned above.

In other words someone who gives up using e-flybar can re-employ the gyros on the tails of other helis (or sell them on to someone else for that purpose) - the actual commitment of funds specifically to an excursion into e-flybar is minimised.

If you go e-flybar on a non-CCPM heli you don't even need the mixer!

By separating out the system it is unlikely that the whole system would be a casualty of a crash.

You would not have to use a CSM tail gyro in the unlikely event that you prefer another brand

Best regards

Colin (CSM)

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11-24-2006 12:04 PM  11 years agoPost 2
J3DI

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Oswestry, Shropshire. UK

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I agree, it doesn't sound the most elegant solution to have 3 separate units to find homes for on the heli but i can see why you would go this way as you have explained.

Keep up the good work Colin, i'd like to see how this takes off(!) I definately think this area of development is the way forward as it has so many positives.

Dan

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11-24-2006 12:35 PM  11 years agoPost 3
Colin Mill

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England

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Hi Dan

Well, with a Raptor, as its not CCPM, it's an easy thing to try. The modification to the head is little more than removing the flybar and its associated links, locking the mixer base to its drive pins (so it acts just as the swash driver) and linking the blades directly to the swashplate (extending the blade pitch balls out to be in line with the hub centre is also good to avoid unwanted phase/delta 3 effects)

If you are interested I can give you some internal settings for the 720s

Colin

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11-24-2006 12:56 PM  11 years agoPost 4
brianbruff

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ireland

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V.flybar
Edited

I smile, cause I've no idea what's going on.

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11-24-2006 12:59 PM  11 years agoPost 5
Edders

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Suffolk,UK

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sounds very intresting

after the conversation I had with colin a we bit ago I got all excited over the mixer (for me it would mean I was able to fly the rex with my cheap transmitter instead of the 9X)

but I wonder if you could scale it down to trex 450 size / weight the performance would be very intresting? I had heard of something like 20% increase of power

Edders

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11-24-2006 01:01 PM  11 years agoPost 6
bobj

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United Kingdom

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Hi Colin

Forgive me been lazy and not doing a search (if you have quoted it already) but do you have a idea of how much more power is available to the rotor with out the flybar?
Could be a interesting development, of course the FAI will never allow it so that 5 sales you won't make:-)

Cheers
Bob

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11-24-2006 01:45 PM  11 years agoPost 7
AV

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PA-USA

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Flybarless head
Colin,

Just heard from Wendi about my 720 and, I'll give it a go. As for the Flybarless head you are working on, lets see how it works out. I appreciate your comments about servo loads. The best test would be with strain gauges on metal out put arms to get a qualitative value.

Look forward to your progress. Also, I am sure Wendi may have already passed on to you my request for a dynamic balancer for RC helis.

Tom

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11-24-2006 01:48 PM  11 years agoPost 8
Colin Mill

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England

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Hi Bob
course the FAI will never allow it so that 5 sales you won't make:-)
So where are the three I don't know about??

I just did the sum and I reckon for a 50 size heli at 1900 rpm the loss to the flybar in the hover is only about 15 watts (1/50hp). However, with the paddles at high angles of attack in 3D it could get up to 200watts (1/4hp). In fast forward flight the flybar has a more profound effect as the paddles generate 'lift' that is acting down and back. When I find a bigger bit of paper I'll work out what effect that could have.

One reason for not doing this development - we don't want you doing even better autos

Colin

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11-24-2006 01:53 PM  11 years agoPost 9
colsy

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Cambridge, UK

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Doesn't, connecting the blade grips directly to the swash, Induce a greater load (Directly), On the swash itself, and the servos.

Colin..

Only Quote From Experience.

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11-24-2006 01:53 PM  11 years agoPost 10
BarracudaHockey

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Jacksonville FL

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Considering the cost of a single 720 wouldnt that make this cost prohibitive for many people or are you planning some sort of package with the gyros to get the price to a reasonable 3 digits?

Andy
AMA 77227
http://www.jaxrc.com

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11-24-2006 01:58 PM  11 years agoPost 11
Colin Mill

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England

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Hi Tom

When I get a minute I'll attack the Raptor we have here that still has a standard head on it and post some pictures.

Although not as good as the strain gauges I have been meaning to make up a little device that acts as a tell-tale on the servo current (that can be calibrated against the stall current of the servo) as a way of looking at this on various controls. I just need cloning to get it done!

Colin (CSM)

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11-24-2006 02:06 PM  11 years agoPost 12
bobj

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United Kingdom

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Hi Colin

------------------
Doesn't, connecting the blade grips directly to the swash, Induce a greater load (Directly), On the swash itself, and the servos
------------------

I suspect you would need small reduction mixer arms on the mainshaft as a direct connection would give you a massive pitch range and make things unduly sensertive.
These would also give the servo's some gearing so reduce the load on them but yes the overal load would have to be higher with out the flybar servo assist.

Cheers
Bob

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11-24-2006 02:06 PM  11 years agoPost 13
Colin Mill

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England

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Hi BarracudaHockey

Well, taking the typical UK street price of a 720 as £130 and say under £50 for the mixer this would give you a system for about £440 or about $800. Was that the sort of 3 figures you were thinking of?

Colin

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11-24-2006 02:11 PM  11 years agoPost 14
colsy

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Cambridge, UK

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Thanks BOB, as Colin mill hasn't commented, then i assume this has been taken into consideration.

Sorry but I'm intrigued.

Colin..

Only Quote From Experience.

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11-24-2006 02:12 PM  11 years agoPost 15
Colin Mill

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England

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Hi Bob

I think I would simply use shorter arms on the servos and greatly reduce the swashplate movement. I take your point though - this would increase the reliance on good tight linkages and swashplate. I think simply increasing the moment arm of the blade pitch balls would be a good solution. The Hobby Taiwan metal grips could easily be modified for the job as could say the Knight grips.

Colin

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11-24-2006 02:13 PM  11 years agoPost 16
Colin Mill

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England

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Sorry Colsy - I'm a bit slow at typing!!

Colin

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11-24-2006 02:15 PM  11 years agoPost 17
hootowl

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Garnet Valley, Pa.

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Colin's suggesting better than half the price of the V-Bar system. 720's are about $200 each.

Wolves don't lose sleep over the opinions of sheep

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11-24-2006 03:34 PM  11 years agoPost 18
Krunder

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Denmark

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Hi

I made some flights with the V-bar / V-stabi, earlier this year I ended up selling the system, but it worked great. I made my setup like this (Runryder member AirwolfRC´s homepage)

http://www.micom.net/AirWolfRC/NFB.html
Swashdriver and a gearing from swash to bladegrips all in one.
I got +/-12° pitch and around 10° cyclic.

The V-bar system has a speed sensor to aviod pithing in FFF, how does the 720 handle that?

Krunder

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11-24-2006 04:08 PM  11 years agoPost 19
MrMel

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Gotland

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Dont forget that you compare prices to VStabi 3 axis systems, There will be a 2 axis which will be cheaper, thats what you need to aim at...

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11-24-2006 04:09 PM  11 years agoPost 20
Colin Mill

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England

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Hi Kruder

Although we have not completely ruled out the possibility of providing a speed sensor option we see it as an incomplete solution to the problem because it cannot (without the use of a second sensor) take account of sideways flight components so cannot assist in avoiding pitching in fast sideways flight. It is also one more thing for the user to set up - to match the speed trim to compensate the pitching tendency of the model. This is made something of a compromise by the latter being head speed dependent.

The heading lock term of the gyro is completely capable of removing pitching in fast forward and sideways flight (much in the way it deals with holding the tail attitude in sideways flight). The SL720 has independent heading lock decay constants for each flight mode that would allow the user to tailor the velocity stability (pitching tendency) of the helicopter in flight to suit different situations much in the way the heading lock decay can be used to provide a controlled weathercocking of the tail when used in the tail gyro.

Colin (CSM)

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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Virtual Flybar - what would you like to have?
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