ADAHRS....

[dynonsupport]

The wing is not going to be a great location, plus I doubt you want to run pitot and static out there.

The tailcone is fine, but you'll want to keep it far away from the AC, since AC draws TONS of current. I'd put it where most people put their remote compass today- up on a shelf right behind the baggage bulkhead, on a tray mounted up top near the turtledeck.

 

[woxofswa]

Thanks for the response. I guess I have quite a conundrum because the air conditioning components also reside on a shelf right behind the baggage bulkhead below the turtledeck.

The A/C system (by Airflow systems) isn't electric so I don't see where it would be a huge current draw. It would only be the fan motor.

I guess my only option is to move the ADAHRS further back in the tailcone, or lower near the floor.

My biggest issue right now it pre-wiring. Besides pitot and static, What all in the form of wires and cables will the box require?

 

[dynonsupport]

Well, if it's not electric, then the AC will be less of an issue. Try and keep it 18"+ away from the fan.

The only wire to the ADAHRS is a D9, with all pins used, straight through to the panel. That's about all the pre-wiring advice we can give for now.

 

[rckol]

The wing is not going to be a great location, plus I doubt you want to run pitot and static out there.

Does the comment that "the wing is not going to be a great location" apply to all aircraft or just the RV-10. Seems like the wing has been a popular location for the magnetometer in the current generation. Plus pitot and AOA are already out there!

 

[dynonsupport]

This will be true of pretty much all planes. The wing is not a good location for a gyro, since it experiences both acceleration and roll when the aircraft rolls. On top of that, static is not out there already.

 

[vlittle]

In a typical installation (all nextgen Dynon), the pitot/static/aoa could be routed to one location (wing tip or aft fuse makes sense).

However, if there are any instruments on the panel that require them (such as a backup D10A), alternate static source or mechanical instruments, this requires routing the lines to the panel as well.

This tends to offend my sensibilities for design elegance.  For a wingtip installation, it also puts the low point of the static system in the wing root, which prevents the proper construction of an in-flight accessible static drain.

Aft-fuse or tail mounted AHARS may still allow a proper static drain to be constructed at a low point somewhere near the panel, so this may be a better location for the AHARS for this reason.  Still not very elegant.

Since we are on the topic, this might be a good time to lobby for a modified AOA/PITOT.  Sounds like if a static port could be incorporated into it, then a wingtip mounted AHARS would be ideal.  Then, the three air lines could run from the AOA/PITOT/STATIC probe a short distance to the wingtip.  The static port itself would be the low point, and it could be heated.   Alternate static would still require a Tee and an air line to the cockpit.

It would be VERY nice if the new AHARS could talk to the D10A as well, eliminating the need for the pitot/static/aoa connections to be routed to the panel for a backup instrument.  Two AHARSs can be connected easily in one wingtip for redundancy as well.

Sorry for the long post, but  you see that packing everything into one box has knock-on consequences.

Vern Little

 

[rfinch]

I'm building an RV-9A QB, and am working on the wings. I plan on a Dynon EFIS, so bought a Dynon heated pitot tube and routed the wires and tubing in the wing back to the wing root.

But I'm confused as to what I should do about the remote compass or nexgen ADAHRS.  I might as well plan for nexgen since I won't get to the panel for 2 or 3 years. So do I buy the remote compass and its wiring harness, and install that in a wingtip and route the wires?  Or should I instead route wires for the nexgen ADAHRS?  Should I be routing the static/pitot tubes to the wingtip then, and not the wing root?  Or can the nexgen ADAHRS sit midway along the wing, near the pitot tube, with therefore a short pitot tube run to it?

Basically, I'm looking for Dynon to advise me and others as to what wiring and tubing routing we should do for a new install about 2 to 3 years from now.

 

[Ken_Kopp]

I wouldn't put an ADHRS in the wingtip since wings flex and twist a lot more than you can tell sitting in the cockpit possibly adding errors to the attitude calculations. I'd suspect with such a significant offset from the CG a bias would have to be incorporated to isolate roll rate and Normal acceleration. With the ADHRS mounted within the fuselage close to the lateral CG of the airplane a pure roll will not induce an Ng (Accel in the vertical plane). At the wing tip, any roll also induces increased Ng. Maybe Dynon has isolated this in their solution...dunno or they provide in input of CG bias based upon the ADHRS location? Also, the wingtips are the most prone to hangar rash, running into fence posts and / or other planes, also more exposed to the elements. Pitot tube mounted Static sources are not normally a very good choice and are prone to significant Ps errors.

Ken

 

[dynonsupport]

We won't be supporting the wingtip for the ADAHRS. As Ken says, it's not a good location for an ADAHRS.

We've packed everything in one box because it makes installation and calibration easier in many cases, and makes the whole system less expensive. It does mean you need to get your pressure lines to somewhere else in the plane, but this isn't much different than many ADAHRS units that are already on the market. With this solution, there is no need to get the ADARS and the remote compass at the same angle since they are in the same box.

We may eventually sell a separate box that is just an AD (pressure) box or just a remote compass, but this will be at additional cost. The current remote compass will not work with the new system.

It's a touch early to be pre-wiring and running tubes, but here are the few suggestions we can give:

The location needs to be within a few feet of the centerline of the plane (in the fuse somewhere basically).

The location needs to be magnetically clean.

You need to run pitot, static, and AoA (optional) lines here.

There will be one D9 on the box, which needs to run to the panel eventually.

Note that in most RV's, behind the baggage bulkhead will be a great location and static is already here.

 

[woxofswa]

>>there will be one D9 cable<<

I can wait for the toys, but I would like to get my wires run and conduits spoken for so I can button up the fuselage and move on.

Will the D9 cable be a generic off the shelf product or a custom OEM creation?  Will it be shielded? Twisted? Ribbon?

Is there product now available for rough wire-in that those of us in the wire stage can get strung?  If not, do you know when such might be available?

Thanks in advance.  I know customers can be a pain sometimes.  Without ever having owned a Dynon product, I am basically committing myself and my project to you guys on faith and reputation alone.  I am sure that I am not alone.  I appreciate that you guys don't want to release something ahead of its time, but by the same token, I hope that you guys can appreciate that those of us who are patiently waiting and willing to commit down the road need some care and feeding in the meantime.  We both are going to need each other down the road for this thing to be a success.

 

[dynonsupport]

The D9 is straight through female-female, so it's something you can find off the shelf, but not if you want it in Tefzel.

We'll be selling one, you can make one, or you can buy one somewhere else. It doesn't need to be shielded, but wires 1&6 and 8&4 need to be twisted.

 

[woxofswa]

Thanks again for the response.

Any idea when your cable will be available for purchase for pre-wire? I will be an immediate buyer.

I hope they don't wait until the whole package is done to release the installation prep items.

 

[dynonsupport]

We don't have release dates for any of the next generation products - screens, modules, and harnesses inclusive. Stay tuned though!

 

[gerry.vandyk]

You call for a "magnetically clean" location for the ADAHRS unit. Does that mean those of us building steel tube fuselages can't use your new system?

Gerry

 

[dynonsupport]

We have not generally had an issue with a compass being inside a steel tube aircraft, as long as the steel doesn't move as you fly. We can calibrate out static errors that the frame causes.

 

[vlittle]

We won't be supporting the wingtip for the ADAHRS. As Ken says, it's not a good location for an ADAHRS.

We've packed everything in one box because it makes installation and calibration easier in many cases, and makes the whole system less expensive. It does mean you need to get your pressure lines to somewhere else in the plane, but this isn't much different than many ADAHRS units that are already on the market. With this solution, there is no need to get the ADARS and the remote compass at the same angle since they are in the same box.

We may eventually sell a separate box that is just an AD (pressure) box or just a remote compass, but this will be at additional cost. The current remote compass will not work with the new system.

It's a touch early to be pre-wiring and running tubes, but here are the few suggestions we can give:

The location needs to be within a few feet of the centerline of the plane (in the fuse somewhere basically).

The location needs to be magnetically clean.

You need to run pitot, static, and AoA (optional) lines here.

There will be one D9 on the box, which needs to run to the panel eventually.

Note that in most RV's, behind the baggage bulkhead will be a great location and static is already here.

Thanks! This information, plus the requirement of twisting the DSAB wires gives us everything we need to prewire. I presume 22 AWG is acceptable.

Aft fuselage it is. This works out because we can tee the pitot/aoa where it enters the fuselage and run fore and aft.

So we need a 9-pin cable, pitot, aoa running to the aft fuse. Time to break out the drill and make the holes.

BTW, for those who are mounting the unit in the recommended location in an RV with a slider canopy (behind the baggage bulkhead, up high)... Ensure that you calibrate the magnetometer with the canopy CLOSED. Opening the canopy will move the steel canopy frame over the magnetometer and mess things up.

One more question for Dynon... I presume we mount the unit level with the fuselage datum, not adjusted to the panel pitch (like the D10A).
Vern

 

[dynonsupport]

Yes, the box should be level with the aircraft in normal flight, not the panel.

 

[vlittle]

A closer look at a tandem setup would best put the AHARS in the aft fuselage, perhaps on the tail deck under the VS. All other stations have large current-carrying wires (baggage compartment/battery compartment) or moving hunks of steel (pushrod ends) or are inaccessible.

The tail deck location would see larger pitch and yaw excursions than a location closer to the cg. Is this an acceptable location?

Vern

 

[dynonsupport]

It'll be better than out on the wings. How's that for a non-answer?

Seriously though - we've yet to deeply test various locations on aircraft, so we're well into speculation-land here. I think we'll need to punt on this for the time being until we can answer more authoritatively.

 

[fhorniii]

As regards the location of the ADAHRS, I am building a plane that has a carbon graphite fuselage shell around a spruce Pratt truss frame. This is a Pioneer 300S by Alpi Aviation. I've read in the past that the magnetometer cannot be placed inside a graphite area and I was planning to put the magnetometer in the wingtip. Will it be a problem to install the Skyview inside a carbon graphite fuselage?