FASST VS XPS

[kgfly]

Not heatshrink, folded acetate or stamped plastic (PET possibly). They are appropriate cases for targeting the market for lightweight Rx, are included in the published data, allow the user to retain the pin labelling even at low weight and can of course be removed for an even lighter weight outcome. I notice you didn't list the weight of the Futaba 7ch Rx with its case, because of course they don't publish it. Doesn't it seem even a little odd to you ?

[DavidH]

Has it ever occured to you that the case the receiver is pictured with might not be the one it is going to come with.

Doesn't seem odd to me, but then I am not wrapped up in all the specs. I have always used what works best for me. Takes a little trial and error to find out what works sometimes.

David

[kgfly]

Excellent points as always David. Yes that occured to me. IMO a more reasonable approach would have been to put no weight at all or an estimate (eg weight < 20g, 7g without case). What they have done is provide what I do not dispute is an accurate but IMO largely useless piece of information for most of the market. Of course for most applications of a 7ch Rx, a few grams here or there don't matter much, which is another reason why their marcom decision is so annoying.

Rant over.

[overspeed]

Seems pretty clear, Take the case off the receiver and the receiver weighs 7 grams. Doesn't seem like BS to me. Seen a few pilots running receivers without the case in micro stuff.

As for the 6EX 2.4. Seem to work OK for CCPM at the XFC. That is the radio that Danny Szabo used.

DavidI'm using the 6EX (2.4) and haven't noticed anything weird about the CCPM, but then I really like my 9C, too.

[Garland]

so for standard mix helis like Bergens etc, this 9C latency crap is worthless? right?

Does the 8U have a even worse ECCPM report card? I wanna use XPS in that also.

[heliboy88]

Rich - The Futaba 7c (and 9c/9z for that matter) have very poor eCCPM performance compared to almost every other radio currently available: http://www.runryder.com/helicopter/gallery/8588/latency_pcm8_avg.gif

I don't know why one would choose an F7c over a DX7 particularly if 2.4GHz is an important part of the solution :dontknow

Hi kgfly,

Sorry for the late reply, and thanks for your every advice ever since. :D
So you mean the F7 also has the 'bad' ccpm performances like the 9C? Can you clarify in what way the eccpm performances are 'bad' with these radios?
The reasons i chose Futaba are:

1) I've been using Futabas for many years from cars, gliders, to helis.
You know what i mean.
2) Since i just started flying (or having fun with RC) again few months
ago, so i just heard the name 'Spektrum' few months ago also.(Sorry
for my ignorance). And you know it's just the so called 'confidence'.
3) This is to be my most concern. About the 'low voltage reboot'(?) of
the spektrum Rx. How can this be solved for me to feel safe to use
it? I'm only flying electric helis, does that mean if i get a ESC with 6V
BEC or get a seperate 6V BEC then i'll be good to go?
Any advice please?

Best regards,
Rich

[kgfly]

Rich,

JKos, the author of the latency tests linked to earlier in this thread, discusses in detail his finding about Futaba's CCPM mixing. The behaviours can be summarised as:

* CCPM channels are not adjacent in the frame and updates for the three channels can be spread across two frames. This causes considerable skew between the servos in terms of their response to a stick change.

* Slew rate limiting. For reasons only known to Futaba, they limit the rate of change of the CCPM channels. This means that if you make a large stick movement, the actual change in commanded position is spread out across several frames. This effectively reduces all CCPM servos to the same speed (about 0.20/60deg) regardless of their inherent capability.

Many people like to stick to a brand that is tried and true and fair enough. Spektrum have been around for several (5?) years, 2 or 3 in the R/C car domain and about 2 now in the R/C flight domain. They have sold many thousands of systems. Their DX6 and DX7 Tx are based on JR platforms with their own RF technology and minor tweaks to the Tx hardware and firmware. Of course there have been some faulty units, as for any similar product, but overall I don't think you have to worry about them as a "fly-by-night" company. I am sure Futaba will still be around in ten years. I don't know about Spektrum but it doesn't bother me, my guess is I will have one or two new Tx over a ten year period. Not everyone feels the same way about new technology or new brands so you have to do what makes sense to you.

The low voltage reboot issue applies to all microprocessor-based Rx but is certainly more of an issue for spread spectrum units which have to not only reboot the micro but also typically scan the band to reqacquire their bound Tx. At the moment it seems that Spektrum have the longest reboot/reacquisition time and possibly FASST the shortest, although there are so few out there (or at least so few folks posting about them) that it is hard to say. Certainly XPS is faster than Spektrum. In the Spektrum Rx range the AR6100 seems more sensitive to power dips than the AR6000 or AR7000 (being so small, perhaps it has less on board capacitance). The AR6200 and AR6300 are brand new so I have not seen any reports about them so far.

The solution is to ensure a properly setup power system for the model that ensures the power supply does not fall below the Rx manufacturer's specifications. Officially this is 3.5V for Spektrum but 4.0V as an absolute bottom floor is safer. Of course 4.0V under load is way below what you should be flying anyway. Whether you run a 5V BEC or a 6V BEC is less important (to this issue) than ensuring the BEC will handle the flight loads without overloading or overheating and shutting down. Even a sub-second voltage dip can be a problem. So on a small heli run a 3A BEC (switched mode if you are using digital swash servos) and on a bigger one, up to a 6A BEC like the new one from Align.

[heliboy88]

Kgfly,

Thanks a million for the detailed explanation of everything. :noteworthy
So i think i won't have problems flying my electric helis with the Spektrum system then. I will look at the DX7 now. :D

Best regards,
Rich

[Fox222]

I'm waiting for the FASST mod myself.

[flymo]

Will the 12z/14mz FASST modules allow the 12z and 14mz to be faster than the DX7? and will they use the trainer port?