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Beer30?

Joined: 23 Sep 2006
Posts: 14

Posted: Mon Oct 30, 2006 10:21 pm Post subject: Fuel sensors

I have a question  for the more experienced builders out there regarding fuel sensors.  I just  purchased a used wing kit for my -7.  It came with the float type fuel  sensors.   My question is, what would the advantages or disadvantages  of capacative sensors over the floats?   I intend on having a fuel  totalizer built into the engine monitor, and will probably install a flop tube  for limited aerobatics.   Thanks in advance for your  advice.

  

  

 Beer30?

  

  

 David  Dalton

   [quote][b]

Ron Schreck

Joined: 10 Jan 2006
Posts: 94
Location: Gold Hill, NC

Posted: Tue Oct 31, 2006 3:51 am Post subject: Fuel sensors

David,

  

 Your post brings up a subject  which merits some discussion.  I often hear builders saying they want  to do "limited aerobatics" so they are installing this or that thingamajig on  their RV.  As delivered, the RV (except the 9 and 10) is capable of many  aerobatic maneuvers and it is a joy to flop about with reckless abandon, knowing  that it will eventually come out upright with the pointy end going ahead of the  tail.  Generally the "as delivered" RV is capable of most POSITIVE "G"  maneuvers and this gives it quite a long list of available aerobatic  options.  David, I'm not picking on you, but just adding a flop tube in one  of your fuel tanks is not going to give you NEGATIVE "G" capability and thus  expand the range of aerobatic maneuvers.  

  

 A carburetor will starve your  engine immediately at negative "G".  Cost of a fuel injection system:  $3000+

  

 After 15 to 30 seconds of  negative "G" flight your oil pressure will go to zero.  Cost of inverted  oil system: $1200+

  

 If you have a standard constant  speed prop, a momentary loss of oil pressure (even possible with inverted oil  system) can cause the prop to go to fine pitch at high power setting and  overspeed your engine.  Additional cost for an aerobatic constant speed  prop: $1500+

  

 Now, if you do spend $6000+ to  truly make your RV "fully" aerobatic you really should do something about that  single lap belt and purchase a parachute just for safety sake. (Also,  remove any ADI (vacuum or electric) with a mechanical ADI or you will  eventually ruin the gyro bearings.)  

  

 And now you are ready to turn  that baby downside up, but the airfoil is not symmetrical so you will really  need to work hard to make it perform inverted maneuvers, and did I mention how  uncomfortable inverted flight is on your body!

  

 Bottom Line:  Most RV's  are capable of limited aerobatics when built according to plans and they are a  blast to fly.  If you want more performance, go buy an airplane that is  purpose-made for aerobatics.

  

 I bring all this up, not to  discourage anybody, but to give those who may be inclined to equip their RV for  "limited" aerobatics something to ponder before you spend the milk money on the  next thingamajig.  Flame away.  Nomex installed.

  

 Ron "Smokey"  Schreck

 RV-8 "Miss  Izzy"

 Gold Hill Airpark,  NC

  

  

  

  

  

 



             Time:      10:21:24 PM        PST US

             From:      "David Dalton"        <ddalton536(at)gmail.com (ddalton536(at)gmail.com)>

       

     > I have a question for the more experienced  builders out there regarding fuel

      >sensors.  I just purchased a used wing  kit for my -7.  It came with  the

      >float type fuel sensors.   My  question is, what would the advantages  or

      >disadvantages of capacitive sensors over the  floats?   I intend on having  a

      >fuel totalizer built into the engine  monitor, and will probably install  a

      >flop tube for limited  aerobatics.   Thanks in advance for your  advice.

      

         

      

      >David Dalton



   [quote][b]

Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Tue Oct 31, 2006 4:11 am Post subject: Fuel sensors

David,

 Advantage = No moving parts to wear and better  accuracy over the range. But, if you will have a fuel flow sensor/computer you  will find that the fuel gauges will become a reference only. 

The mechanical  sensors will do fine.

  I have the capacitive sensors on one OBAM  aircraft that has no fuel flow computer and would recommend them in that  case. But, have fuel flow sensor on the 6A and it gives much better useful  info.

 Dale Ensing

 ---

_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

charlieray(at)optonline.n
Guest

Posted: Tue Oct 31, 2006 3:43 pm Post subject: Fuel sensors

How DARE you have the GALL to actually make  sense!

  

 Do not archive

 [quote]   ---

Beer30?

Joined: 23 Sep 2006
Posts: 14

Posted: Tue Oct 31, 2006 8:49 pm Post subject: Fuel sensors

Ron,

 Thanks for the words of wisdom. You bring up some good points.  I was already planning on the CS prop to get the climb performance (I live in Denver), I had considered and knew of the need for the inverted oil system (to protect the engine and keep the belly clean) but did not know the cost.  I hadn't considered the CS prop's ability to maintain pitch, although the Super Decathlon I flew had a CS prop, and seemed to do OK with negative G stuff.   

 In any event, you have me thinking about this, and more research is certainly in order.  Thanks to everyone else who responded.  I think I'll stick with the float sensors and the fuel totalizer.  

 Keep on riviting,

 DD

 On 10/31/06, Ron Schreck <ronschreck(at)alltel.net (ronschreck(at)alltel.net)> wrote: [quote]  David,

 Your post brings up a subject which merits some discussion.  I often hear builders saying they want to do "limited aerobatics" so they are installing this or that thingamajig on their RV.  As delivered, the RV (except the 9 and 10) is capable of many aerobatic maneuvers and it is a joy to flop about with reckless abandon, knowing that it will eventually come out upright with the pointy end going ahead of the tail.  Generally the "as delivered" RV is capable of most POSITIVE "G" maneuvers and this gives it quite a long list of available aerobatic options.  David, I'm not picking on you, but just adding a flop tube in one of your fuel tanks is not going to give you NEGATIVE "G" capability and thus expand the range of aerobatic maneuvers.   

 A carburetor will starve your engine immediately at negative "G".  Cost of a fuel injection system: $3000+

 After 15 to 30 seconds of negative "G" flight your oil pressure will go to zero.  Cost of inverted oil system: $1200+

 If you have a standard constant speed prop, a momentary loss of oil pressure (even possible with inverted oil system) can cause the prop to go to fine pitch at high power setting and overspeed your engine.  Additional cost for an aerobatic constant speed prop: $1500+ 

 Now, if you do spend $6000+ to truly make your RV "fully" aerobatic you really should do something about that single lap belt and purchase a parachute just for safety sake. (Also, remove any ADI (vacuum or electric) with a mechanical ADI or you will eventually ruin the gyro bearings.)   

 And now you are ready to turn that baby downside up, but the airfoil is not symmetrical so you will really need to work hard to make it perform inverted maneuvers, and did I mention how uncomfortable inverted flight is on your body! 

 Bottom Line:  Most RV's are capable of limited aerobatics when built according to plans and they are a blast to fly.  If you want more performance, go buy an airplane that is purpose-made for aerobatics. 

 I bring all this up, not to discourage anybody, but to give those who may be inclined to equip their RV for "limited" aerobatics something to ponder before you spend the milk money on the next thingamajig.  Flame away.  Nomex installed. 

 Ron "Smokey" Schreck

 RV-8 "Miss Izzy"

 Gold Hill Airpark, NC

     Time:  10:21:24 PM PST US

     From:  "David Dalton" <ddalton536(at)gmail.com (ddalton536(at)gmail.com)> 

     > I have a question for the more experienced builders out there regarding fuel

      >sensors.  I just purchased a used wing kit for my -7.  It came with the

       >float type fuel sensors.   My question is, what would the advantages or

      >disadvantages of capacitive sensors over the floats?   I intend on having a

      >fuel totalizer built into the engine monitor, and will probably install a 

      >flop tube for limited aerobatics.   Thanks in advance for your advice.

      >David Dalton

 	  Quote: 	

[b]

Ron Schreck

Joined: 10 Jan 2006
Posts: 94
Location: Gold Hill, NC

Posted: Wed Nov 01, 2006 6:58 am Post subject: Fuel sensors

You live in Denver!  That brings up some other  points:  A constant speed prop would be a great addition.  At  high density altitudes a fixed pitch is really at a disadvantage.   Sure, you lose engine power at altitude regardless of the prop, but with a  constant speed you are starting out with far superior takeoff performance in the  first place.  I was in Greeley, Colorado two weeks ago and did some  formation flying and aerobatics.  The "floor" is above 7000 feet for  aerobatics and performance is noticeably different from the 2000 foot  "floor" which is typical out here on the east coast.  I can't imaging how  difficult negative "G" aerobatics might be at 7000+  feet!      

     About that Super  Decathlon; I haven't flown one and don't know if the prop is aerobatic or  not.  (Aerobatic props have counterweights that cause the prop to go to  coarse pitch when oil pressure fails).  Many entry level and intermediate  aerobatic airplanes don't use aerobatic props.  I guess they are betting  that oil pressure fluctuations will be brief and/or occur at less than full  throttle operation.  Similarly, you could get away without an aerobatic  prop on an RV if you are willing to take similar chances.

      Side note:   Check out the eyeballs of pilots who have done serious negative "G" acro.   Looks like they have been on a 3-day bender!  The condition (blood shot  eyes) isn't dangerous to health but just points out how hard negative "G" is on  the body.  Positive "G" has similar effects such as G-Rash.

  

 Ron  Schreck

 RV-8 "Miss  Izzy"

 Gold Hill Airpark,  NC

     

  

  

  

 

      >Ron,

      

      >Thanks for the words of wisdom. You bring up  some good points.  I was

      >already planning on the CS prop to get the  climb performance (I live in

      >Denver), I had considered and knew of the  need for the inverted oil system

      >(to protect the engine and keep the belly  clean) but did not know the cost.

      >I hadn't considered the CS prop's ability to  maintain pitch, although the

      >Super Decathlon I flew had a CS prop, and  seemed to do OK with negative G

      >stuff.

      

      >In any event, you have me thinking about  this, and more research is

      >certainly in order.  Thanks to everyone  else who responded.  I think I'll

     > stick with the float sensors and the fuel  totalizer.

      

      >Keep on  riveting,

      

      >DD



   [quote][b]

panamared3(at)brier.net
Guest

Posted: Wed Nov 01, 2006 8:28 am Post subject: Fuel sensors

On the other hand, I purposely built my RV6 for aerobatics.  I do positive 

and negative maneuvers, I fly the sportsman and intermediate acrobatic 

maneuvers.  I find the RV6 a delight to fly aerobatics.  I do like it much 

better than the Super Decathlon.  The RV6 is not a Extra 300, nor does it 

cost $300,000.

I do have inverted oil, and no it does not keep the belly clean.  I do fly 

with a 7 point Hooker Harness (ratchet) and it is no more uncomfortable 

upside down as it is right side up.  Actually my RV6 upside down is a lot 

less painful than the Super Decathlon I used to fly.  Personally, I would 

not own an airplane that did not have Hooker Harnesses in it.

I do not fly with a CS prop.  In my opinion it would only give me about 100 

FPM more in climb and it would cost me 10 kts in speed, it also would cost 

me  45 lbs and increased complexity and maintenance costs.  I believe that 

the single best thing to do for acrobatics is to keep it light.  The extra 

45 lbs puts a lot of extra stress on the crankshaft, and if you want a CS 

prop and want to do serious acrobatics then you will probably want an 

aerobatic crankshaft as well.

As for keeping it light, that applies to my aircraft as well as to me the 

pilot.

As for fuel injection.  A lot of RV owners have it and they never fly 

upside down.

Bob

At 10:48 PM 10/31/06, you wrote:

 	  Quote: 	
		  Ron,

Thanks for the words of wisdom. You bring up some good points.  I was 

already planning on the CS prop to get the climb performance (I live in 

Denver), I had considered and knew of the need for the inverted oil system 

(to protect the engine and keep the belly clean) but did not know the 

cost.  I hadn't considered the CS prop's ability to maintain pitch, 

although the Super Decathlon I flew had a CS prop, and seemed to do OK 

with negative G stuff.

In any event, you have me thinking about this, and more research is 

certainly in order.  Thanks to everyone else who responded.  I think I'll 

stick with the float sensors and the fuel totalizer.

Keep on riviting,

DD

On 10/31/06, Ron Schreck 

<<mailto:ronschreck(at)alltel.net>ronschreck(at)alltel.net> wrote:

David,

Your post brings up a subject which merits some discussion.  I often hear 

builders saying they want to do "limited aerobatics" so they are 

installing this or that thingamajig on their RV.  As delivered, the RV 

(except the 9 and 10) is capable of many aerobatic maneuvers and it is a 

joy to flop about with reckless abandon, knowing that it will eventually 

come out upright with the pointy end going ahead of the tail.  Generally 

the "as delivered" RV is capable of most POSITIVE "G" maneuvers and this 

gives it quite a long list of available aerobatic options.  David, I'm not 

picking on you, but just adding a flop tube in one of your fuel tanks is 

not going to give you NEGATIVE "G" capability and thus expand the range of 

aerobatic maneuvers.

A carburetor will starve your engine immediately at negative "G".  Cost of 

a fuel injection system: $3000+

After 15 to 30 seconds of negative "G" flight your oil pressure will go to 

zero.  Cost of inverted oil system: $1200+

If you have a standard constant speed prop, a momentary loss of oil 

pressure (even possible with inverted oil system) can cause the prop to go 

to fine pitch at high power setting and overspeed your engine.  Additional 

cost for an aerobatic constant speed prop: $1500+

Now, if you do spend $6000+ to truly make your RV "fully" aerobatic you 

really should do something about that single lap belt and purchase a 

parachute just for safety sake. (Also, remove any ADI (vacuum or electric) 

with a mechanical ADI or you will eventually ruin the gyro bearings.)

And now you are ready to turn that baby downside up, but the airfoil is 

not symmetrical so you will really need to work hard to make it perform 

inverted maneuvers, and did I mention how uncomfortable inverted flight is 

on your body!

Bottom Line:  Most RV's are capable of limited aerobatics when built 

according to plans and they are a blast to fly.  If you want more 

performance, go buy an airplane that is purpose-made for aerobatics.

I bring all this up, not to discourage anybody, but to give those who may 

be inclined to equip their RV for "limited" aerobatics something to ponder 

before you spend the milk money on the next thingamajig.  Flame 

away.  Nomex installed.

Ron "Smokey" Schreck

RV-8 "Miss Izzy"

Gold Hill Airpark, NC

Time: 10:21:24 PM PST US

From: "David Dalton" <<mailto:ddalton536(at)gmail.com>ddalton536(at)gmail.com>

      > I have a question for the more experienced builders out there 

 regarding fuel

       >sensors.  I just purchased a used wing kit for my -7.  It came 

 with the

        >float type fuel sensors.   My question is, what would the 

 advantages or

       >disadvantages of capacitive sensors over the floats?   I intend on 

 having a

       >fuel totalizer built into the engine monitor, and will probably 

 install a

       >flop tube for limited aerobatics.   Thanks in advance for your advice.

       >David Dalton

<http://www.matronics.com/Navigator?RV-List>http://www.matronics.com/Navigator?RV-List

<http://www.matronics.com/contribution>http://www.matronics.com/contribution

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Wed Nov 01, 2006 9:01 am Post subject: Fuel sensors

In a message dated 11/01/2006 9:00:22 AM Central Standard Time, ronschreck(at)alltel.net writes:

  	  Quote: 	
		  Side note:  Check out the eyeballs of pilots who have done serious negative "G" acro.  Looks like they have been on a 3-day bender! 	


 Sean Tucker was giving a talk at OSH a few years ago and said he knew he was pulling some "real" Gs when he could "feel his eyeballs touching the inside of his sunglasses"

  

 Ow...

  

 Mark do not archive

  [quote][b]

_________________
From The PossumWorks...

Ron Schreck

Joined: 10 Jan 2006
Posts: 94
Location: Gold Hill, NC

Posted: Thu Nov 02, 2006 1:51 am Post subject: Fuel sensors

Bob,  

  

 I agree that keeping it light is extremely  important.  Just curious though, how do you manage to keep the RPMs below  red down when you are on a long downline?  I fly a lot of formation  with others that have FP props and I have to make slow speed descents  when leading in order to keep their RPMs under red line.  I'm guessing that  you have a "climb" prop which would increase the tendency to wind up on the  downline as well.  I  don't compete in aerobatics so I have no need for inverted oil and all but I  sure like having the CS prop so I never worry about the RPM.  I have a  Whirlwind 200RV which is not much heavier that a metal FP.

  

 While we are on the  subject.  I'm looking for a parachute and would appreciate hearing from  others that fly RV-8's.  What make/model works best?

  

  

 Ron  Schreck

 RV-8, "Miss  Izzy"

 Gold Hill Airpark,  NC

  

  

 --> RV-List message posted by: Bob <panamared3(at)brier.net (panamared3(at)brier.net)>

       

      On the other hand, I purposely built my RV6  for aerobatics.  I do positive 

      and  negative maneuvers, I fly the sportsman and intermediate acrobatic  

      maneuvers.  I find the RV6 a delight to  fly aerobatics.  I do like it much 

       better than the Super Decathlon.  The RV6 is not a Extra 300, nor does it  

      cost  $300,000.

      

      I  do have inverted oil, and no it does not keep the belly clean.  I do fly  

      with a 7 point Hooker Harness (ratchet) and  it is no more uncomfortable 

      upside down as it  is right side up.  Actually my RV6 upside down is a lot  

      less painful than the Super Decathlon I used  to fly.  Personally, I would 

      not own an  airplane that did not have Hooker Harnesses in  it.

      

      I do  not fly with a CS prop.  In my opinion it would only give me about 100  

      FPM more in climb and it would cost me 10 kts  in speed, it also would cost 

      me  45 lbs  and increased complexity and maintenance costs.  I believe that  

      the single best thing to do for acrobatics is  to keep it light.  The extra 

      45 lbs puts  a lot of extra stress on the crankshaft, and if you want a CS  

      prop and want to do serious acrobatics then  you will probably want an 

      aerobatic  crankshaft as well.

       

      As for keeping it light, that applies to my  aircraft as well as to me the 

       pilot.

      

      As  for fuel injection.  A lot of RV owners have it and they never fly  

      upside  down.

      

       Bob



   [quote][b]

panamared3(at)brier.net
Guest

Posted: Thu Nov 02, 2006 7:52 am Post subject: Fuel sensors

>I agree that keeping it light is extremely important.  Just curious 

though, how do you manage to keep the >RPMs below red down when you are on 

a long downline?



 > Ron Schreck

Good questions on the RPM on the downline.  One of the major drawbacks of 

the RV in acrobatics is the speed build up on the downlines.  A comparison 

with  the purpose built acrobatic One Design:  pilots report on the 

downline with fixed pitch prop that the drag is so high it is hard to 

exceed 180 MPH.  In my RV I exceed 180 MPH in straight and level 

cruise.  So managing RPM is an important task.



I do it by retarding the throttle.  I do get criticized severely by the 

competition crowd, but then they are not flying RVs.  Also the competition 

guys and the airshow types often fly way above redline.  Some have told me 

they are very happy at 3100 RPMs.  Of course they also tell me they do an 

engine rebuild every year during the off season.  If you can not afford a 

yearly engine rebuild, and who can, then keep the RPMs close to redline.



A few hints

1.  Retard the throttle during downlines, I call this energy 

management.  Most acrobatic types will tell you energy management is 

keeping the speed up, in my case it means keeping the speed down.  Conserve 

the slow speed.  Example, while at cruise speed you want to do a split 

S.  I do an immelman to reduce the speed below 100 KTS and then do the 

Split S and pull out around 140 KTS.



2.  Pulling Gs will reduce your speed which in turn will reduce your RPMs.



3.  If you do not want to jockey with the throttle during maneuvers, then 

you can set your power setting so that 2700 RPMs will equal redline at a 

certain speed.  I use 160 KTS and 21" MP equals 2700 RPM.   As long as I 

stay below 160 KTS I am below redline.



Unfortunately on long descents a fixed pitch will not work as well as a 

constant speed.  Engine people tell me it is bad for the engine to be at 

very high RPM (2700) and very low MP (10").  So in decent the best I can do 

is about 1500 FPM at 17" MP for a short period of time before I exceed 

redline.



The RV is just too fast sometimes.  Never thought I would say that.  So 

when doing acrobatics, speed management is critical, no I should say super 

critical.  But it can be done, just enter the vertical downlines just above 

stall speed and watch your airspeed.



Interestingly the speed difference between my RV and an Extra 300 is not 

that much.  One thing (not the only thing) that makes the Extra 300 such a 

better aerobatic aircraft is that it can pull 10 Gs as compared my 6 

Gs.  And nothing except impacting with the earth will kill airspeed (or 

RPMs) faster that high Gs.  Of course impacting with the earth is a 

extremely high G maneuver!!?!



Bob

chaztuna(at)adelphia.net
Guest

Posted: Tue Nov 07, 2006 5:11 am Post subject: Fuel sensors

Ron,

  Good advice. However, I have to take exception with your cost assessment for using fuel injection versus a carburetor. Aircraft Spruce sells the Precision Silverhawk system for $2400. Considering that you can sell your new or overhauled carburetor for $1000 (or more if new), that makes the "difference" only $1400. The ability to run lean of peak with fuel injection will allow you to recoup a savings in future fuel costs.

 Charlie Kuss



 

 [quote]David,

  

 Your post brings up a subject which merits some discussion.  I often hear builders saying they want to do "limited aerobatics" so they are installing this or that thingamajig on their RV.  As delivered, the RV (except the 9 and 10) is capable of many aerobatic maneuvers and it is a joy to flop about with reckless abandon, knowing that it will eventually come out upright with the pointy end going ahead of the tail.  Generally the "as delivered" RV is capable of most POSITIVE "G" maneuvers and this gives it quite a long list of available aerobatic options.  David, I'm not picking on you, but just adding a flop tube in one of your fuel tanks is not going to give you NEGATIVE "G" capability and thus expand the range of aerobatic maneuvers.  

  

 A carburetor will starve your engine immediately at negative "G".  Cost of a fuel injection system: $3000+

 Snipped[b]

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