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Van's AHRS mount?

I

Iluke

Well Known Member
Hi everyone.

I'm wondering if anyone has used the AHRS mount kit Vans offers for the 7/9 and if so did it work well?

Van's mounting kit puts the unit down low, just off the bottom skin, behind the baggage bulkhead. I've seen on several builders sites that others locate it up high, just under the top skin.

I'm wondering if there is any reason to fabricate something up high rather than use the one Van has already engineered?

I have not yet settled on a brand of EFIS, but all the manufacturers say the AHRS/ADAHRS should be positioned away from magnetic influences (ferrous metal, current carrying wire runs). There is no ferrous metal down low in the aft fuselage but there are wires. I will be running wires back to my LED tail light along the floor. I don't know if LED lighting draws enough current to make that wire run a problem.

Any thoughts would be appreciated.

thanks
Ivan
 
Iluke said:
Hi everyone.

I'm wondering if anyone has used the AHRS mount kit Vans offers for the 7/9 and if so did it work well?

Van's mounting kit puts the unit down low, just off the bottom skin, behind the baggage bulkhead. I've seen on several builders sites that others locate it up high, just under the top skin.

I'm wondering if there is any reason to fabricate something up high rather than use the one Van has already engineered?

I have not yet settled on a brand of EFIS, but all the manufacturers say the AHRS/ADAHRS should be positioned away from magnetic influences (ferrous metal, current carrying wire runs). There is no ferrous metal down low in the aft fuselage but there are wires. I will be running wires back to my LED tail light along the floor. I don't know if LED lighting draws enough current to make that wire run a problem.

Any thoughts would be appreciated.

thanks
Ivan
Click to expand...

Hello Ivan,

Good question. This mount was designed for the GRS77 AHRS used in G900X equipped RVs, so it provides a rigid mount that is more than adequate for smaller, lighter ADAHRS like the GSU25.

We use this bracket in our RV-7A to mount both of the GSU25 ADAHRS, and there is room left over. We are pleased with the relatively low vibration levels seen by the ADAHRS when using this installation method.

a1w_gCP2UTSndJIPPaBRpLnhkVoWidEyDWCw83rmOQO6uqiARr5NChwK4byop7_DdJBUcDl06UaYj-qxn6dDea0clllVyQRRe_MZmKCJE54eT9F4d2n8Uv57NoOfMsG3awbpuGIOyXWhXf0Yg9es4-zu4sCD7c6T-2GL7sRjN5jp_r2OpRqr0JNYijwVovKl-IJYFpGb_GpqOwxUpI-HTL2SKs1mY1Fz4hCpNhhQ78R7OoBrcR2t_j6HR5mYz5QQMn8sHswoyJNCIMri3EOUDMMTSbcb-jMO-lzU8duFe4k7PIaGqi8nVe9f-n3DvzD3__EPEnuXlwqo3K2PjqV5te6WXFIuQnbBliX3rl7bWczQWo-LYM-CeVkhq86ASG_5f8uhjHgjMFTZeD8KOfvtgu0RSBu-XeWGF3GbO-QRtkjnVDh5hmz3YRH3kWUVvdhekYSnvyzQaOzNuqHyp9e2ujudsDz0TK96nzONnnGRgF2DSdyzivql7RCT_-1cmHdkzZwFDr_1zpuLeJl8Xbfazz5rF5J14Dd6BftYYZeTRP8u35txSrhBb9FBq33onjg8oOeMYGvg6fUylaDWyXpaTnS3cUY9kv-ztpj5xWDW4NokYG939ZiI=w920-h518-no


Thanks,
Steve
 
I have used the Vans mount for GR AHRS. Easy to install and mount the AHRS, however if you are going to use an autopilot (I dont) then the pitch servo will be close. The servo motor has permanent magnets in it as well as DC power on it. Just something to think about.:)
 
I put mine in front of the rear deck, away from the steel seat belt anchor cables.
DSC03880_zpsh46q8dre.jpg
 
I just put in a couple cross-angles on the aft longerons and used brass screws, it's easy to do...

000_0183_zpse51nj4pm.jpg
 
Thanks all for the quick responses! Several good options there and I appreciate the photos.

Perhaps the more pertinent question would be.. How sensitive to magnetic interference is a ADAHRS? Specifically, would the 20 gauge wires carrying low amperage power to an LED taillight be a problem, say. . . 12 inches away? 18 inches?

I guess I'm trying to put some empirical data to the need to locate the thing "away" from magnetic sources. I know a big steel part such as the canopy frame or flap actuator would be a problem, as I suspect would a DC motor such as autopilot servo. But how far away do I need to put it from general wiring runs? Does anyone have experience within an ADAHRS located near (12 inches?) of a lighting wire run and found it to work OK?

Thanks again everyone!
 
Iluke said:
Thanks all for the quick responses! Several good options there and I appreciate the photos.

Perhaps the more pertinent question would be.. How sensitive to magnetic interference is a ADAHRS? Specifically, would the 20 gauge wires carrying low amperage power to an LED taillight be a problem, say. . . 12 inches away? 18 inches?

I guess I'm trying to put some empirical data to the need to locate the thing "away" from magnetic sources. I know a big steel part such as the canopy frame or flap actuator would be a problem, as I suspect would a DC motor such as autopilot servo. But how far away do I need to put it from general wiring runs? Does anyone have experience within an ADAHRS located near (12 inches?) of a lighting wire run and found it to work OK?

Thanks again everyone!
Click to expand...

Hello Ivan,

As shown in the image above from our RV-7A, we have power wiring and an autopilot servo in the vicinity of the GSU 25 ADAHRS units, and this is not a problem because we do not attempt to locate the sensitive magnetometer inside the ADAHRS unit.

This design supports many more ADAHRS installation locations than a design that has an internal magnetometer. You can also mount the GSU 25 ADAHRS using regular steel AN bolts and not have to worry with using brass fasteners.

Thanks,
Steve
 
Last edited:
Dynon ADAHRS shelf custom made RV-6A

Dynon advised me not to place the ADAHRS close to the pitch servo. The D means it contains a remote compass in addition to AHARS so it doesn't want iron or electromagnetics nearby. I made a shelf across the longerons just behind the 1st bulkhead aft of the pitch servo.

EJlg9mOY92jIcfW-Mi5SuDj-Vzu1EcdM87reXlRQ0i3ZP25IKDor1nTJvDbLpG3blOSH5KOhEnn0fwJJs3BtESenikSIbdWfuEfqY1mny-62sorl8KezPAMXTTuw1BoFUxRAcRnZctWx8iSlYnF7feYW-NpW15Ve7696Giof2SQAvzgfqqu4PZvhapYnctkL4ZYaUYCNEI9Tgx4z9qWDhrARRnVAmrzja0LgRGrPIJYfoGXlRVqp4Fq4pjugnfbkRA6vNn9-6O2XGzoviA-KBcCa9qgNdrslj0QR6VsLt36OwXkJZ8cLDG4gaSB71gjCwlA3ivadYg1UzJzI16dG2MqQsa5iF5_HTE5YES4_JTtp5qNzlVbrJJYEAGgMrMlc_zq554bVKubHLPgyRdlKDzwf_qrYqVYeyt1JymlYofgbRw8d1nX44kmpn_8IALQELA7jDs-21EghFdWk__vRoTKIqO-Y_6vjSsLdvteICuDqNHWX1o4QyZd8h4O-3Wt3OQAnVBdpk1stO-ZkoHYuzgdIz8B01Fayd4kJz-rRn-egcXzp3nGD6Ka0w7-KrpehRzOPlktm-ifPmKIDEZIbb8V4EPngPkoANyTBJVX3T-JOqV9OALBC=w936-h702-no


m3wGIBe_0kgqx8IIELH-Dh_6cRaNRmRT6UPBCEsi8BJnCEliKZz1BfI1wp0EWQXx-1dCBe5L7QbS31dbTYjnDK-VllvswusS3yvMElgRvjTvvpLZXiBlIJjNL72Umg0kOVNir5_L0Wu2QJaRzseA2Om5jvoctpumkFPRu_c9OZAqwZUexGKerAeUZUwumk1YGR-4jeq698xRGPzvrQN73OsQXdu3iTyCagt63Z0O37C-3bfGdp2URNkIk3_vOd_xWp2nKRRajr2o44bqFS0u96Fa_mIiINO-HxDI6YW0TqzPhIDsVkjmyD42CfaL818TWn17IgJFaG21VFFM79dK3sHai0CwP08JZY3PdjVfllP63VmFg3r8AUYUp8wib072ijbV2FKsISJe6gJlmEKxB9C2SsHCReIU3q8Bh52C-YDQ3Dr1gqO_lc-fALm8gxNvzoVyfz_K66yYoHqhigU26S3IqcPE-Ll5ZGaOf6DxCuM53ykyg0biThQn6NO8UAV-QhDjAMLlTXZEaNZooA9sFQlHpT-x9bqSWF8EEXB7s8rPCqKSxVuQgAKOEMolVJtSTkX89MreLOfspixWvPSAIuAHjQ7vbrXylYfYAAntNzrUAyuGZw32=w936-h702-no




********** Postscript: **********

I sent the photo below to Dynon and they say "The steel cables can certainly cause a problem with the compass. The should not be any closer than 18" to 3' away from the ADAHRS modules."

J2X5YxJjgDgOdj3P3pLSv9UVvAWKCIdaY9TowDvcXaIYHoR730sibUhEUjgn3q9G6at5EDfzrvgdyaNopxXDsTgI4qURpRkx0a49LuTmj46Grq5t1bap7jZSiGOd7mudv4A1tllIGnJFaegGwT2cVWAHawj1p_4Dbkwrf9wgfGtV4h5XcI7jk4WXi14Akr5H06bK7ZO9v_GB0Rh6FpU0Rm_Soq_grgv1xE9CGaOTqdo6ULcaJYYI_JYr9wrRNPYq5Z8A61EHRs1qOoJOBOCFSt05KD4Lnlz-ysnozLDdGcNTCI8zz4QsdUphrzUH8oUdN1y_9IAtknbhgM5tQNXJBKXUPoyLTqyY4-t2_mQDdZtsESnd5DyamccF9R7bttFOqRoStA_7l_8cL1xOgAZMG4CbL0eS20XMSXdD_Rb-oB80l5rfKkGSU6MACv4u0ET8Th1e_gN-a7EvuZ00rPtE7ewI2zaKCwUIlO0NvzZUefK36dSK7D29fcGfAEW99id32Hmcp7RXaa9KtM41NCQ19gESLgvu74Wpn8636fhrCEW7k-7J6IUryDXaAZXAWT7OH88PVaVj_-isBd_sfi3wQUBQkqJyqX1bOTjEnPjW8DZxwPW8JjfG=s925-no


NDrv8r put it in a similar location and reports no problems, as of 2017 he's been flying for five years. http://www.vansairforce.com/community/showthread.php?t=92650

A local -9A builder here in Newport News, VA, Solomon9A, also reports no problem and he's flying for a year now (05/2017) so I'm gonna leave mine as-is.
 
Last edited:
Will those steel seat belt cables interfere? I remember reading somewhere someone had that issue. But I've been wrong before
 
Electrogunner said:
Will those steel seat belt cables interfere? I remember reading somewhere someone had that issue. But I've been wrong before
Click to expand...

I remember reading that somewhere also, they would move the cables and the compass heading would change.
 
I used it for my MGL SP2/SP4 combo. I used aluminum standoffs and brass screws and it's been working fine so far.

But to be honest, if I was to do it again, i'd just stick them both to the surface with industrial velcro instead of the standoffs. It can be a little difficult to work with if you're installing in a QB fuse, but if you use a digital level, you can zero the surface orientation to the longerons in 2 axes prior to drilling.

IMG_0911.JPG
 
Carl Froehlich said:
John - where did you get the material for the shelf?

Carl
Click to expand...

Hi Carl,

I don't know if you are addressing Carl Courte or John Bright.

The shelf in post #9... I made that from .032 2024 T-3 Alclad using 4" seamers, plastic hammer, and fly cutter. Not easily visible is crease is put in the lower 3/8" of the flange to resist bending in the aircraft's X direction. Now if the ADHARS would just perform well with the proxim shoulder harness cables... TBD.
 
Last edited:
g3xpert said:
Hello Ivan,

Good question. This mount was designed for the GRS77 AHRS used in G900X equipped RVs, so it provides a rigid mount that is more than adequate for smaller, lighter ADAHRS like the GSU25.

We use this bracket in our RV-7A to mount both of the GSU25 ADAHRS, and there is room left over. We are pleased with the relatively low vibration levels seen by the ADAHRS when using this installation method.

a1w_gCP2UTSndJIPPaBRpLnhkVoWidEyDWCw83rmOQO6uqiARr5NChwK4byop7_DdJBUcDl06UaYj-qxn6dDea0clllVyQRRe_MZmKCJE54eT9F4d2n8Uv57NoOfMsG3awbpuGIOyXWhXf0Yg9es4-zu4sCD7c6T-2GL7sRjN5jp_r2OpRqr0JNYijwVovKl-IJYFpGb_GpqOwxUpI-HTL2SKs1mY1Fz4hCpNhhQ78R7OoBrcR2t_j6HR5mYz5QQMn8sHswoyJNCIMri3EOUDMMTSbcb-jMO-lzU8duFe4k7PIaGqi8nVe9f-n3DvzD3__EPEnuXlwqo3K2PjqV5te6WXFIuQnbBliX3rl7bWczQWo-LYM-CeVkhq86ASG_5f8uhjHgjMFTZeD8KOfvtgu0RSBu-XeWGF3GbO-QRtkjnVDh5hmz3YRH3kWUVvdhekYSnvyzQaOzNuqHyp9e2ujudsDz0TK96nzONnnGRgF2DSdyzivql7RCT_-1cmHdkzZwFDr_1zpuLeJl8Xbfazz5rF5J14Dd6BftYYZeTRP8u35txSrhBb9FBq33onjg8oOeMYGvg6fUylaDWyXpaTnS3cUY9kv-ztpj5xWDW4NokYG939ZiI=w920-h518-no


Thanks,
Steve
Click to expand...

Steve,

Is there any issue with the ADHRS lower than the static vents? Would a little water in the system cause an issue.

I went through some extra effort to mount my box up high to prevent such an issue.
 
climberrn said:
Steve,

Is there any issue with the ADHRS lower than the static vents? Would a little water in the system cause an issue.

I went through some extra effort to mount my box up high to prevent such an issue.
Click to expand...

Hello Joel,

Good point. I can't tell from this picture, but I believe the static ports are plumbed together according to the plans which creates a high point above the static ports for which the static line to the ADAHRS units is connected preventing this from being a problem.

I think there is even another low point before the ADAHRS units in the event a little moisture condensed in that line.

Thanks,
Steve
 
johnbright said:
Hi Carl,

I don't know if you are addressing Carl Courte or John Bright.

The shelf in post #9... I made that from .032 2024 T-3 Alclad using 4" seamers, plastic hammer, and fly cutter. Not easily visible is crease is put in the lower 3/8" of the flange to resist bending in the aircraft's X direction. Now if the ADHARS would just perform well with the proxim shoulder harness cables... TBD.
Click to expand...

Impressive you made that with hand seamers and not a metal brake.

Carl
 
Dynon ADAHRS shelf custom made RV-6A

Electrogunner said:
Will those steel seat belt cables interfere? I remember reading somewhere someone had that issue. But I've been wrong before
Click to expand...

Dynon is cautious about my location but two flying builders report no issue so I'm gonna leave it as-is. Ref my edited post #9 above.
 
Electrogunner said:
Will those steel seat belt cables interfere? I remember reading somewhere someone had that issue. But I've been wrong before
Click to expand...

That's location has worked well for me with no interference from the seat belt cables.

Mine are located just forwarded of the first bulkhead aft of the baggage compartment and are made of two pieces of light AA. I have carried rifles, tools, camping gear, you name it in the aft end of my baggage compartment and it hasn't impacted my compass.
 
ADAHRS shelf

I made one to fit betweek the J-stiffeners and the F707 bulkhead. The aft flange fits behind the bulkhead. I have a pencil drawing scanned if anyone is interested. Mine os not flying yet but I have flown with another builder with a similar set up and his Dynon was rock solid even through loops and rolls.
vhycg1.jpg
 
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