e-flite safe receiver

[ericrw]

Hi, As anyone put a e-flite safe receiver in a taildragger. ? I`m wanting to put the safe receiver in my Mustang.

[MattyB]

The RX doesn't know how many wheels your plane has - just fit it, configure as per the donor plane, test the compensations are acting in the correct direction and go fly. If you can switch SAFE off for the first takeoff and fly in full manual  I would still do that though in case your TX setup is off.

Edited By MattyB on 19/09/2016 19:30:36

[John Lee]

Need a bit more information on what you are wanting to do.

If you mean the Spektrum AR636 Rx as sold as a Rx then yes, no problem whatsoever - see here for all you need to know.

However if you mean can you remove the Rx from one of e-flite's BNF models & put it in the Mustang then that all depends.

The Rx in the Apprentice is dedicated to that model only & is not programmable so will only operate correctly if all the controls operate in the same sense as the Apprentice and the Rx is mounted in the same orientation as the Apprentice. If, for instance, the Mustang's elevator needs reversing to operate in the correct sense then the Rx stability control would fight against it & is totally unsuitable.

Some AR636 variants sold with BNF models have firmware that is not programmable. See this thread for more information. You will need to be very careful if you are thinking of buying or using anything other than a new in pack Rx.

[ericrw]

Just received my E-flite ASRX11 (EFLR310013). My intention is put it into my Starmax P51 1600mm w/s. The original receiver, is being replaced by the ASRX11. The original ESC is 70 amp Brushless with BEC, as to whether I will have to change this to suit the safe receiver is something I don`t know ! Any advise please !!

[John Lee]

The EFLR310013 is what I referred to as the 'Apprentice' receiver in my post above. It will only work correctly if it's mounted in orientation exactly as per the Apprentice (Apprentice Manual page 20) and the transmitter with the primary controls set to 'Normal' (Apprentice Manual page 23).

If that happens to be correct then the ESC should be fine.

However if you find any of the controls need reversing DO NOT REVERSE ON THE TRANSMITTER as the SAFE functions of the receiver will work against you & you will find the model uncontrollable. If you need to reverse you must find a way of doing that mechanically.

[ericrw]

John, I believe the rx has to be across the c of g line, which makes it awkward as the battery lies across the line in my model. however, I went on "youtube" and watched the Horizon Hobby video. They stated that as long as you install the safe rx pointing forward or backward, as long as it is in line with the fuselage, it`s acceptable to put it onto the side of the fuselage. Any thoughts ?? Eric.

[John Lee]

Eric, does the HH video refers to their programmable receivers which you can 'tell' what the orientation is?

I take it that when you say you want to put it on the side of the fuselage it means mounting it with the Rx base on the fuselage side?

The EFLR310013 does not have this facility and I've never been able to find a way of operating it other than as shown in the Apprentice Manual, sorry. I don't have any experience of mounting the Rx away from the CG but in theory it should not be critical as it will still detect pitch, roll & yaw albeit the correction rates may be fractionally different.

You say that you have just received the Rx - have you considered changing it for an AR636 which will do what the EFLR310013 does & is fully flexible in its programming? If bought by mail order then the Distance Selling Regulations give you the right to cancel for 7 days after receiving the goods.

[ericrw]

Unfortunately, I bought my rx from off Ebay. I`ve been onto the "Rcgroup" forum, following thisand I intend to fit it to my Mustang and bench test it to see what the results are. I cannot do this at the moment, as I`m awaiting a new Nose and props from Hobbyking. The cause of my interest in Safe receivers.

[Denis Watkins]

Hi Eric, do not put a stabiliser anywhere but bang in the centre of the aircraft, on the C of G, facing forward.

No other place is suitable, and the trouble it causes cannot be trimmed out.

I stress, this unit, if it is to be used correctly, has to take priority over the battery position

Built a "Nimrod" pod on the aircraft to carry the battery, if the stabiliser is to be given a chance

Edited By Denis Watkins on 21/09/2016 18:24:26

[Martin Harris - Moderator]

I've no direct experience but assuming these use gyro technology, there should be no restriction where you put them. A gyro can be mounted anywhere on an airframe - even at a wingtip - as it detects rotation in whichever geometric plane it is mounted - unless you have a model where, for example, the wingtip rotates through a different angle than the fuselage or the fin yaws more than said wingtip?!?

Edited By Martin Harris on 21/09/2016 18:28:56

[Denis Watkins]

Woe Martin, these are not regular gyros, but are for fixed wing stabilisation through the control surface servos.

They have a top, and front, for fitment, and only work on the C of G

A NASA single missile gyro would probably maintain flight fitted anywhere

But these are very simple gizmos that control 3 axis independently when fitted at the centre, facing the right way

[Martin Harris - Moderator]

I've always assumed they are essentially 3 gyros in a single box with some clever electronics, Dennis. If so, my comments should apply and that box simply needs mounting in the correct orientation anywhere in or on the airframe - but if they use a different method of detecting roll, pitch and yaw about a single point, I stand to be corrected.

Edited By Martin Harris on 21/09/2016 19:16:06

[ericrw]

Dennis, I`ve googled "Nimrod" pod but all I get is Soul music !!!

[Denis Watkins]

Martin, you are absolutely right, that a gyro set anywhere along an axis, would stabilise that axis, e.g. for "roll", the single gyro could be mounted on the top of the fin and work. But these units have 3 gyros set very close together to control 3 axis independently, thus the central fitment location is vital.

Eric, Nimrod was said as a joke, but referring to making extra space being built onto the model if need be, to accommodate both the lipo and the stabiliser centrally

Edited By Denis Watkins on 22/09/2016 07:24:18

[Bob Cotsford]

Sorry Denis, I don't follow that, surely your fin mounted 3 axis 'gyro' would still be subject to rotation in all three axis so why would it not work there?

[Denis Watkins]

Sorry Bob, let me elaborate, as I should have done in the 1st place. A single gyro can be bought, and a single gyro set on one axis through the corresponding servo or servos would stabilise that axis, which was Martins argument.

But as you say Bob, and I said earlier, these 3 axis units need fitting at the absolute center of all 3 axis, namely centred at the C of G for them to operate all 3 axis independently, as they do increadibly well on 2 of the models I have them fitted, for gusty days

All comments so far on gyros are correct, I was just pointing out that 3 axis stabilisers have to be "sense" set correctly in the model, facing the correct way on the C of G to work properly.

[Bob Cotsford]

it's the 'on the C of G to work' that I'm having trouble with Denis - surely they will be subject to the same angular rotation/acceleration wherever they are mounted, or does some other factor come into the mix? Are they upset by lateral acceleration for example?

[Kim Taylor]

Posted by Denis Watkins on 22/09/2016 10:09:27:

Sorry Bob, let me elaborate, as I should have done in the 1st place. A single gyro can be bought, and a single gyro set on one axis through the corresponding servo or servos would stabilise that axis, which was Martins argument.

But as you say Bob, and I said earlier, these 3 axis units need fitting at the absolute center of all 3 axis, namely centred at the C of G for them to operate all 3 axis independently, as they do increadibly well on 2 of the models I have them fitted, for gusty days

All comments so far on gyros are correct, I was just pointing out that 3 axis stabilisers have to be "sense" set correctly in the model, facing the correct way on the C of G to work properly.

Whilst Denis may well be correct for the elusive 'ideal world' scenario, in practice I don't think it's as critical as all that.

I've just been upstairs to have a look at the (standard) installation in my Apprentice and the receiver is mounted somewhat behind the longitudinal c of g and against the right hand side of the fuselage, so a good 80mm or so away from the notional centre line.

But as stated, they must be mounted 'right way up' (i.e. 'base' downwards) and 'right way round' (i.e. wiring to the rear) for correct operation. Use servo reverser leads or reverse mechanically if required on your particular application. The thread on RCgroups is very informative but also very long, but if you trawl through it, most problems have been resolved on there.

Kim

[MattyB]

Posted by Denis Watkins on 22/09/2016 07:23:08:

Martin, you are absolutely right, that a gyro set anywhere along an axis, would stabilise that axis, e.g. for "roll", the single gyro could be mounted on the top of the fin and work. But these units have 3 gyros set very close together to control 3 axis independently, thus the central fitment location is vital.

...but if you look at the instructions for an AR636 they make no mention of fitting on the CG - as long as it is pointing in the right directions it should work:

"Installing the Receiver
1. You can install the receiver under the canopy or in the bottom of the fuselage. The servo pins must point toward the nose or tail of the fuselage.
2. Connect the servo and telemetry leads to the receiver.
3. Use double-sided foam tape to secure the receiver."

I do not use Spektrum kit but have installed and trimmed out models with Lemon and Eagletree stabilisers. In both instances I have found the stabiliser location to be CG agnostic.

Edited By MattyB on 22/09/2016 11:47:45

[Martin Harris - Moderator]

Bob's explanation is exactly as I understand the situation. Gyros sense angular rotation and are virtually unaffected by vertical or horizontal displacement so can be mounted anywhere on an object. Alignment with the (geometric) plane which is being monitored is essential so as long as the receiver is mounted in the correct orientation it can be anywhere in or on the model and work correctly.

[Denis Watkins]

OK guys, have some consideration for readers who may invest their hard earned cash in these stabilisers then fit them incorrectly, due to the advice shown, and be dissatisfied with the operation.

I did not design the 3 axis stabilisation systems available, so I follow the manufacturers instructions. My advice of fittment, level in the model, the right way round, at the C of G, is based on involvement in only 5 installations, from 3 different manufacturers. These suggestions are not my opinion, but just a precis` of manuals. The post asked for help, I thought I was helping.

[ericrw]

I have been overwhelmed by the amount of info from "RCgroups". But the advice regarding the fitting of the "Safe" rx is as Denis states.

[MattyB]

Posted by ericrw on 22/09/2016 13:49:57:

I have been overwhelmed by the amount of info from "RCgroups". But the advice regarding the fitting of the "Safe" rx is as Denis states.

Can you link to that post/set of posts for us? I can only comment on what I see from the Apprentices I have looked at in the flesh; the RX is not mounted on the CG as per a previous post in this thread. Nor do the instructiosn for the AR636 say that RX needs to be mounted on the CG either (as per my previous link). Maybe some manufacturers state this in their instructions, but it does not seem to be true of HH. They are after all the OEM for SAFE RXs.

Edited By MattyB on 22/09/2016 14:22:54

[Denis Watkins]

The fitting of a stabiliser at the C of G ensures then prime pitch axis is set correctly, what is the problem with fitting this equipment correctly?

[MattyB]

Posted by Denis Watkins on 22/09/2016 14:31:14:

The fitting of a stabiliser at the C of G ensures then prime pitch axis is set correctly, what is the problem with fitting this equipment correctly?

No problem, but you are asserting what is "correct" which seems to be in direct contrast with what is written in the instructions from Horizon Hobby for the RXs that the OP is intending to use. The factory fitted position of the Apprentice SAFE RX is also not on the CG, yet it operates fine. Also it is sometimes not possible to mount a stab on the CG, so having a little wiggle room around installation positions can be important.

I am not saying what you are saying is fundamentally incorrect (I suspect fitting on the CG may have been more critical before solid state gyros with specialised software came along), but it is clearly not supercritical with this generation of products. If it were HH would be a lot more picky around installing/specifying the location of their RXs, particularly given the Apprentice is one of their best selling products.

I just looked up the Eagletree Guardian instructions, and whilst they do recommend putting it near to the CG and aligned with the direction of flight the instructions also state that "...the Guardian will compensate for small mounting errors". It sounds to me like these devices are now advanced enough to have software compensation incorporated to allow a more flexible range of mounting locations, which makes sense given they are primarily aimed at the less experienced who may not yet understand the importance of CG and accurate RC equipment installation.

Edited By MattyB on 22/09/2016 15:50:21