REFLECTOR: electrical sys design
KeithHallsten
KeithHallsten at quiknet.com
Fri Feb 25 00:30:41 CST 2005
MessageTerry,
I'm also planning to use the GRT EFIS. At this point I'm planning a dedicated PFD on top, with a multi-mode Moving Map/Graphical Engine Info/PFD under it. My thinking is that I will always want the primary flight instruments right in front of me, but if that unit goes south, I can use the lower GRT display as a backup. The lower unit will usually be in moving map mode, except during leaning or evaluating a potential engine issue. The GRT EIS 6000 will provide engine indications the rest of the time. My backup moving map will be the GPS (both panel-mount and handheld).
One nice thing about the GRT hardware is that it has dual power inputs. It's connected to BOTH electrical busses, and it doesn't even skip a beat if one bus should go down. This goes a long way toward that simplicity of operation that we're looking for.
Yes, I do plan to put my critical enroute devices on the "endurance bus", with an alternate feed switch. The endurance bus will normally be powered through a diode from the main bus. In case I need to shed load, I'll flip the alternate feed on and then shut down the main bus. Two switch flips gets me to "endurance mode".
I will be working out the details of my electrical system over the next few months, and pulling wire. I hope to be ready to do the big avionics buy at OSH!
Keith Hallsten
----- Original Message -----
From: Terrence Miles
To: 'Velocity Aircraft Owners and Builders list'
Sent: Thursday, February 24, 2005 6:14 PM
Subject: RE: REFLECTOR: electrical sys design
Keith,
Thanks for the outline! I didn't know until a recent conversation w/ Don George that I likely couldn't put a 40 amp alternator on the vacuum pad. (I am no vacuum too). I had hoped for relatively equal capacity systems, for load planning and distribution. I guess not at this juncture, but 20 amp is plenty if I can fit a descent amp hr pair of batts up front. I guess that's another challenge.
I plan separate electronic igs from separate batt buses. I will be doing the dual AHRS system from Grand Rapids EFIS and would like to put them on separate DC distrib systems...but I am not that far along in planning and dual flight data backup might not be realistic...example only one pitot/static system...so where do you say "enough." Beside the electron part of this, the GRT yahoo group has some issues with data integrity/backup and data transfer between the Tru Trak AP, and the Garmin and the internal GRT (non-cert) GPS when filing IFR. I need to read the manuals.
I am use to more complicated systems with electrical abnormal/emergency procedures with at least two heads in the cockpit all the time...I may need to dumb down since I know it only me now. You could write an "Alternator Inop" checklist that included de-powering what was unnecessary. For me I'd be chicken to turn off the pitot heat, for fear I'd be in brain overload or distracted and fail to turn it back on if nec. Are you mounting panel on/off switches for your non-essential download components or will wire stuff to something like "essential DC" and "non essential DC" and just depower the named bus with a cockpit on/off control?
It sounds like you thought this thru really well. Thanks for the ideas.
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of KeithHallsten
Sent: Thursday, February 24, 2005 2:15 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: electrical sys design
Terry,
I'm just working on my electrical system design, and Bob Nuckolls has been a tremendous resource. You will enjoy the seminar, and learn a few things, too!
I think the problem with dual 40-amp alternators will be finding a practical setup for two belt drives. It's do-able, but I think unnecessary.
I have elected to go with a 60-amp B&C alternator (which is a modified Nippon Denso, with external regulation and precision balancing) and a little SD-8 gear-driven backup alternator on the vacuum pump pad (no vacuum system). It is extremely unlikely that we will ever have an electrical load that exceeds 40 amps, even with pitot heat and all the lights, bells, and whistles you can install. The 20-amp overhead (from 40 to 60) is will provide plenty of margin for battery charging and "contingencies".
I figure the 8-amp backup alternator is just to keep the "endurance" bus up to stretch battery reserve until finding a suitable place to land and get the main alternator fixed. Since I also plan to carry 2 batteries, this should keep me in electrons until fuel exhaustion, at which time I will already be on the ground. If the main alternator is out, I plan to shed load until the little 8-amp alternator can carry the few amps needed to keep the key en-route devices operating. This will include a GPS, primary EFIS, a Comm radio, and the transponder, and a LED to throw a little light on the panel. These will be backed up with hand-held devices independent of the ships' electrical system. If your analysis of your minimum enroute load shows 8 amps to be inadequate, B&C also offers a 20-amp alternator that will mount on the vacuum pump pad.
Since the Velocity airframe has no "known ice" capability, I do not believe that it is necessary to plan to carry the pitot heat load indefinitely. Maybe long enough to pass through a layer, but that would be only for a short duration. Therefore, there is no need to have enough alternator to run the heat for the entire flight; the batteries can make up any difference.
I'm also going with 2 batteries, but with 215 lbs in the pilot seat, it probabbly won't be primarily for balance! Some of the EFIS and engine monitor equipment has trouble with the voltage sag during engine start, and I want my engine gauges (oil pressure, etc) to be available immediately upon start. The extra capacity and redundancy also appeals to me, though it is arguably overkill, since I plan to primarily fly in VFR conditions (trips with my wife).
Regards,
Keith Hallsten, XLFG w/ IO-540
Lincoln, CA
----- Original Message -----
From: Terrence Miles
To: 'Velocity Aircraft Owners and Builders list'
Sent: Thursday, February 24, 2005 11:05 AM
Subject: RE: REFLECTOR: electrical sys design
Jim, Greg, Alex,
Thanks for the stories, the great explanation and the good advice. The Reflector is a great reference. Believe me, I will keep all this in mind and build my skills and experience slowly...and I follow the point about the Velo's slow roll rate make RV-8 a more exciting aerobatic platform. I too have XC as my primary use. That said, I gotta son who flew the F-18 and well... we never been "blue side down" together yet. I'll take my time learning. Don't worry. The T-38 had very stubby wings and giant ailerons...this is going to be a lot different, I know.
New topic: I am headed to Bob Nuckol's AeroElectric seminar in about a week. It will be just outside of St. Louis. Anybody building down there? I plan to ask him about the advantages and feasibilities of two 40-amp alternators, versus say a 60-amp and a 25-amp and ramifications on engine build up/instalation that this choice entails. Also the regards internal regulators versus external regulars and advantages for cockpit warnings/indications. I am going w/ the XL-RG-5 and likely the LY 540 K and being only 150 lbs, I already decided on two batts for CG!!
Anybody else have an electrical question or two that I can ask for the group?
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Jim Sower
Sent: Wednesday, February 23, 2005 7:53 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Aerobatics: Rolling about a point
Terry,
Aileron rolls in my experience are positive G maneuvers. A full acrobatic airplane can do aileron rolls quite nicely without negative G (for the most part - like except for demos of multiple multiple rolls with no altitude change). Like, by the time the airplane figures out that the nose should be dropping, you're not upside down any more. The problem with the Velocity is A) limited roll authority, and B) large lateral (rolling) inertia that has to be overcome result in painfully slow roll rates. One way to compensate for this is: start level at your entry speed (you mentioned 185 kias), yank in a lot of back stick (4-5G?) and snap your nose up 10* or more before you start the maneuver. You don't have to climb, just establish your velocity vector at least 10* up. Then put in all the stick and rudder you have. The swept wings of the Velocity will help with your roll rate to the extent you have positive G and full rudder. If you're heading uphill (even if your altitude hasn't changed yet) you are in a position to scoop out a good bit without losing all that much altitude. Starting anything remotely like level, the sorry roll rate and high inertia of the Velocity will cause you to scoop out so hell wouldn't have it, so be sure to be going smartly uphill when you start. Whatever else happens, once you start DON'T STOP (unless you fully intend to do a split-S).
By way of perspective, military fighters do not have inverted fuel or oil. The ones I flew had around 10 sec of inverted fuel and no oil at all. A great deal of ACM maneuvering with swept wing fighters involves "rudder rolls" which as the name implies uses a lot more rudder than aileron. Demo planes (Blues, T-Birds, etc.) have very elaborate fixes to give them full inverted fuel and oil.
By NO means do any rolls below 4000 - 5000 AGL until you've done a LOT of them at high altitude. Even when you do it as best the airplane is able to, it's so awkward and sluggish that it isn't even any fun.
More better, take Alex's advice - do this stuff in an airplane that can do it right ... Jim S.
Terrence Miles wrote:
Hey. Thanks Alex. I understand that explanation better. I know I have lots to learn about carnards. I am filing your reply in my "ops" box, but could do me this last favor?
Let me say it all back to you. Let's just say that I am in level, unaccelerated flight at 185 kts and 5000 feet. Let's also say to hold all this constant, I need +2 pitch on my attitude indicator. If I leave the power alone, then raise the deck angle to +10, neutralize the elevator, and than apply full left aileron, then you are saying that the carnard will continue to pull me "upwards" (that is 90 degrees from a line defined from cannard wing-tip to wing-tip.) ...so the to watch me from an in-trail position I am sort of cork screwing thru the air?
If I understood you right, can't this carnard factor be countered with a tad of down elevator (and not zero G) so as to keep the nose on a near constant spot on the horizon, and maybe roll-out back wings level at something near my entry pitch angle of +2 with little altitude change?
Regards,
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Alex Balic
Sent: Tuesday, February 22, 2005 12:00 PM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: Aerobatics: Non center line rudder
Hi Terry-
About the aileron roll maneuver - you need to think about the difference in lift points on the canard vs. the standard fixed wing- if you see these as arrows pointing straight up from the fuselage, it is easier to understand - normally these forces are fighting gravity- in the case of the standard there is a single large lift vector centered right around the center of mass, on the canard, there are two lift vectors one in front, and one behind the center of mass. when you flip the standard up side down, all you need to do it change the angle of attack, and the lift vector goes through the floor instead of the top of the fuselage. on the velocity, you can not change the angle of attack to negative, because it is not set up to have a negative angle of attack, so even a simple aileron roll will be more like a barrel roll because the lift vector of the canard will not go negative- it is just like going through an aileron roll with constant back pressure on the stick of a standard planform aircraft- so if you are not careful, when you roll 180 and hesitate because the nose is not going where you think it will, then it tends to perform more of a split S. The Berkut company had their demonstrator doing a lot of interesting things (before it crashed) it could do loops, and some rolls too, but the roll rate was probably double of the Velocity, so they could get away with more.
Anyway, best to make some friends in the RV community so you can go out on Saturday morning and get your fix- that is pretty much what I have done!! I can't really think of any 4 place that beats the Velocity in cross country comfort- even though the Lancair is faster, it is not as roomy or stable or quiet......
Alex
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On Behalf Of Terrence Miles
Sent: Sunday, February 20, 2005 12:32 PM
To: alex157 at direcway.com; 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Aerobatics: Non center line rudder
Alex,
Thanks for the advice. Actually the RV8 was a contender, but you freeze out your backseater (in my case wife) on the cross country flights...which is my principal use. I don't think the RV10 is stressed for aerobatics. My only experience with acro is in a T-38 in 1968 doing about 300 kts. So it's been a while, and add to that I have limited time in SEL recips. Sorry for sounding so stupid. I am just trying to get an understanding of accelerate/decelerate capabilities and more on the flight characteristics of a carnard. I am getting the XL so those rudders are way out there and don't work in tandem. Thanks for your input. I get your point about sustained level inverted flight is different with a cannard design.
I still don't think of an aileron roll maneuver as ever going negative. It you start w/ the nose up +10 from level I can't invision losing altitude either. About the cuban eight...but I would want to execute constant-heading half rolls without the airplane fishtailing due to any possibly needed non-centerline rudder inputs to compenstate for torque influences w/ larger throttle changes. Is this an issue? Have you got a comment there? As a small aside, my Saturday acro occasionss would not include any intentional neg g's! Yuk. Thanks for the welcome and for getting back when you have a minute.
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Alex Balic
Sent: Sunday, February 20, 2005 12:01 AM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: WANTED: Acro contacts
Hey Terry,
Welcome to the reflector!
About the velocity doing aerobatics, the canard design in general, and the Velocity in particular does not lend itself well to any negative G maneuvers due to the load being shared by both the wing and the canard, in most other planforms, the wing does all of the carrying, so if you want to go inverted, you just need to fly the wing at a positive angle of attack with the ground. If you try a roll with the velocity, you might pull it off, some have, but chances are, as soon as you go inverted, you will find that there isn't enough down elevator to keep the nose level, and the canard is going to pull you really hard toward the center of the earth, and you will end up doing an un-commanded split-s. If you like doing Aerobatics, even Saturday morning style, you would be better off in an RV which is a blast to fly that way.
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On Behalf Of Terrence Miles
Sent: Saturday, February 19, 2005 9:10 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: WANTED: Acro contacts
Hi,
I should enjoy my ignoble status while it lasts. I have the honor to
be the very newest running nose, wide-eyed kid on the block. The kit
gets delivered in a month or so. In fact I can't seem to get my own email out (reflector at tbvf.org) so I had to use the reply function to get this on the Reflector. Sorry Dave.
I've got a quick kind survey question on acro. I bought the V kit for xc reasons, but are any of you out there doing cuban eights? Is the airplane any good as an acro platform? I know it can take the G loading...but what about roll rate with rudder deflection not centerline? Rudder and aileron size and effectiveness? I didn't understand a thread in the archives about dishing out of an aileron roll...did they mean like barrel roll? If you raise the nose just a little and bang the stick to the left won't it just roll around a point w/ very little if any heading change, as opposed to barrel roll where the flight path simulates a corkscrew as opposed to a spinning top?
Are there and VNE problems w/ say doing a simple split S and no speed brake? The only acro I have done is in jets, so I am a little lost on this stuff. Has anyone developed any target speeds/power settings for continuous cuban eights? Anybody doing in trail formation stuff that I could talk to off line?
Thanks for helping with this. When I become more informed myself, I hope to somehow return the favor down line.
Terry
Now back to your regularly scheduled program....
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of davedent at comcast.net
Sent: Saturday, February 19, 2005 7:18 PM
To: rwhenderson at msn.com; Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: WANTED: West Coast CFI (SF Bay Area)
Check with Steve Murphy. He gave me my company check ride. Also has checked out many others. He will charge you a small fee for the check ride and light fees for the training in your plane. Plus his cost for fuel to come to your airport. He live up in the Reno area.
He had no problem with me seeing I had 1500 hrs in canards before flying my Velocity. I now have 60 hrs on it since last March.
I'm not a CFI but if you need time in a Velocity before you fly yours come by and we can make it happen.
Dave N32XL
LVK
-------------- Original message --------------
> Anyone know any good instructors on the West coast? I'm looking for a CFI
> with Velocity experience in the San Francisco Area for an insurance check
> ride & sign-off.
>
> Must be a CFI w/ at least 50hrs in a Velocity (SUV preferred, but not
> required). Any referrals would be greatly appreciated!
>
>
> Thanks,
>
> - Rob Henderson
> rwhenderson at msn.com
>
>
> _______________________________________________
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