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RV3 low speed

Hi all,
I just bought a just finished RV3 and I started the test flights.
After some trimming to make it flying straight, I am trying to get all the speed it should give me.
Engine: O-320 150 Hp
Propeller: Ed Sterba 68x76 wood
At 2000 ft I can get a modest TAS of 132 Kts, full throttle and full rich.
The propeller turns at 2540 RPM.
No way to get 2700 RPM...
In the incoming days I will check magneto timing and throttle...
Any suggestion is welcome!
 
sounds like too coarse of a prop. I think the catto on my 6A (160 HP variant) is 68x72, though not directly comparable across MFGs or RV models. Even at 2500 RPM, 130 KTAS seems low unless the fairings and pants are off and even then seems low for a 3, WOT, and at low altitude, though I don't know much about the 3. Ensure that linkage is allowing full throttle and mixture arm travel all the way to the stops.

You want a prop that will turn at least 2700 at 8000' and WOT (engine maxing out around 75% power), so that same prop down at sea level will require throttle reduction to stay under 2700 (engine producing 100% power) when everything is right. With your prop, you probably won't even get 2400 at 8000', probably less.

Larry
 
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sounds like too coarse of a prop. I think the catto on my 6A (160 HP variant) is 68x72, though not directly comparable across MFGs or RV models. Even at 2500 RPM, 130 KTAS seems low unless the fairings and pants are off and even then seems low for a 3, WOT, and at low altitude, though I don't know much about the 3. Ensure that linkage is allowing full throttle and mixture arm travel all the way to the stops.

You want a prop that will turn at least 2700 at 8000' and WOT (engine maxing out around 75% power), so that same prop down at sea level will require throttle reduction to stay under 2700 (engine producing 100% power) when everything is right. With your prop, you probably won't even get 2400 at 8000', probably less.

Larry

Thank you Larry,
I will check throttle linkage, leaning and magneto timing just to be sure.
Then I will perform additional tests at 8000 ft and possibly install a MAP gage.
At take off I can get initially 2200 rpm that go to 2340 on climb.
I will do this next Sunday and then let you know about the checks. Something must be wrong, I was expecting at least 150 KTS TAS at 2500-3000 ft
 
Thank you Larry,
I will check throttle linkage, leaning and magneto timing just to be sure.
Then I will perform additional tests at 8000 ft and possibly install a MAP gage.
At take off I can get initially 2200 rpm that go to 2340 on climb.
I will do this next Sunday and then let you know about the checks. Something must be wrong, I was expecting at least 150 KTS TAS at 2500-3000 ft

Do you have a fuel flow gauge? Checking fuel flow will be a method of ensuring that carb is not somehow restricting fuel or air to the engine.

Larry
 
Do you have a fuel flow gauge? Checking fuel flow will be a method of ensuring that carb is not somehow restricting fuel or air to the engine.

Larry
Yes I do have a flow meter, but needs a set up while it is reading values from 24 to 30 GPH... At least there is a correlation between the leaning and the GPH that makes sense.My impression is that the fuel flow works fine, I tried to lean and I can reduce fuel up to 50% before having the typical leaning vibrations or sensible power loss. The air filter looks clean... I am curious to see if the carburetor valve opens to full or if there is a limitation. The average fuel burn is around 8,5 GPH on a 6 hours trip back, average speed was depressing (123 KTS...)
 
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The average fuel burn is around 8,5 GPH on a 6 hours trip back, average speed was depressing (123 KTS...)

Something is way out of whack. At 3000', my 6A (should be at least 5 kts slower) will get 160 kts at around 8.7 GPH or so. 160 kts @ 8 GPH at 8000' Your 150 vs my 160 should still net an advantage to the 3.

Definately worth getting a MAP guage on there to see what you are pulling. Can even get a cheap vacuum gauge from the auto store and convert vacuum to MAP They measure the same thing, just present it with different numbers.

The fact that you get 2200 RPM on the take off roll, but only 2500 in cruise is perplexing and makes me wonder about drag issues. or problems in the pitot or static system. Did GPS speed correlate with TAS in any logical way? Wind forecast data should at least put you in the ball park when correlating. If no GPS, did time vs distance travel match up to the TAS with wind correction?

Larry
 
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Hi Larry,
all flights were recorded on Skydemon and I changed several time direction to calculate the average wind. About aerodynamics I can tell you some improvements came removing the "carbon look" plastic film from cowling and wheel fairings, but we are still away from expectations.
 
Hi Larry,
all flights were recorded on Skydemon and I changed several time direction to calculate the average wind. About aerodynamics I can tell you some improvements came removing the "carbon look" plastic film from cowling and wheel fairings, but we are still away from expectations.
 

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Hi Larry,
all flights were recorded on Skydemon and I changed several time direction to calculate the average wind. About aerodynamics I can tell you some improvements came removing the "carbon look" plastic film from cowling and wheel fairings, but we are still away from expectations.
 

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A data point for you from my RV-3. 160 hp IO-320. Catto prop details shown in photo. 170 KIAS. At 2350 rpm I get about 148 KTAS.
 

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Hello Gustavo,

did you buy the dutch registered RV-3 from planecheck? It had some carbon fiber look wrapping on it.

IIRC there was quite some corrosion on the outside of the cylinders - that got me thinking about the internal condition of the engine. Did you do a compression check? Check all the stuff that's been mentioned above, you are way below typical RV-3 speeds with an O-320. You should almost touch Vne with that engine.

We've got a RV-3 with an 115 hp O-235 and get ~145 kts at WOT. Ed Sterba prop 68*64.
 
A data point for you from my RV-3. 160 hp IO-320. Catto prop details shown in photo. 170 KIAS. At 2350 rpm I get about 148 KTAS.

I was up yesterday in the 6 and slowed down to get some #s for you. At 3000' I was doing 132 KTAS at 2250 RPM. You have a coarser prop and less front plate drag, so in theory should be getting quite a bit more speed than I was at the same RPM. Don't really see how this is an engine issue. RPM is RPM and your RPM doesn't produce the same speed as I or the other 3 guy posting above. That leaves drag and speed indication issues. The sterba prop properly will not do as well as the catto's that we have, but this shouldn't account for more than a few knots. I am still thinking that the prop is over pitched and the reason for not reaching higher RPMs, but could also be moderate issues with engine performance. Could also be RPM indicator issues and not really turning the prop at that speed you think it is; Then we're back to engine issues.

Larry
 
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Hi Larry,
all flights were recorded on Skydemon and I changed several time direction to calculate the average wind. About aerodynamics I can tell you some improvements came removing the "carbon look" plastic film from cowling and wheel fairings, but we are still away from expectations.

Most phones have GPS. Download a little GPS speed display app for you phone. The go up and fly four cardinal points at a constant IAS and altitude. Then record TAS and GPS speed after stabilized for each. On this site, you will find a spreadsheet to put all that data into and see the variance, if any, with the wind corrected out. This will tell us if your actual speed is matching what you are seeing in the cockpit. Improper static port placement or leaks can create very large variance in indicated IAS relative to actual, as can leaks in the pitot systems (lower than actual only).

Larry
 
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Hello Gustavo,

did you buy the dutch registered RV-3 from planecheck? It had some carbon fiber look wrapping on it.

IIRC there was quite some corrosion on the outside of the cylinders - that got me thinking about the internal condition of the engine. Did you do a compression check? Check all the stuff that's been mentioned above, you are way below typical RV-3 speeds with an O-320. You should almost touch Vne with that engine.

We've got a RV-3 with an 115 hp O-235 and get ~145 kts at WOT. Ed Sterba prop 68*64.

IMHO, external rust has no bearing on engine performance or even a clue to how it was maintained. My 6 sits on the ramp and has visible corrosion in areas around the cylinder. Borescope shows healthy cylinders with no poc markings from corrosion. Engines that don't leak oil tend to have more rust issues, as there is no oil coating to protect them. One of the unseen benefits of the Lycoming drip ;-)
 
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Download a little GPS speed display app for you phone

This is what Gustavo has been doing by using the very popular, in Europe, navigation app SkyDemon.
Looking at his flight, though not flown on a triangular or quadrangular course, it reflects the low speeds he is reporting. Ok, he had a climb during that flight.

Was that flight flown at WOT (Wide Open Throttle), is the arm hitting the max travel stop on either the carb or throttle body?
The prop RPMs look ok to me, but for not being able to reach 2700RPM full power. What about the RPM in a WOT descent?
 
This is what Gustavo has been doing by using the very popular, in Europe, navigation app SkyDemon.
Looking at his flight, though not flown on a triangular or quadrangular course, it reflects the low speeds he is reporting. Ok, he had a climb during that flight.

Was that flight flown at WOT (Wide Open Throttle), is the arm hitting the max travel stop on either the carb or throttle body?
The prop RPMs look ok to me, but for not being able to reach 2700RPM full power. What about the RPM in a WOT descent?

Thanks, I didn't understand what the Speed demon data was. So, speeds truly are low, so not an indication issue though he didn't share what RPM produced that data. That leaves drag. He has pretty much the same size prop as the other RV3 poster, yet getting substantially slower speed at the same RPM. That takes engine performance off the table and leaves us with drag or some other aerodynamic issue that explains the differences IMHO. Though I suppose there could be some type of flaw with the propeller affecting performance. The same plane with the same sized prop spinning at the same RPM should produce reasonably similar airspeeds at level cruise, at least for fixed pitch props. CS props are a different animal. It could also be that the RPM reported to the pilot is not the same as the actual RPM of the propeller, in which case that data is irrelevant. If he thinks the prop is spinning 2500, but really spinning 2100 then we are back to engine performance issues.

If it were me, I would get some type of strobe based RPM reader to confirm the RPM indication; Probably $25 on amazon. Most of us can feel and hear the RPM, but wouldn't expect a brand new plane owner to be able to do that.

Larry
 
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Hello Gustavo,

did you buy the dutch registered RV-3 from planecheck? It had some carbon fiber look wrapping on it.

IIRC there was quite some corrosion on the outside of the cylinders - that got me thinking about the internal condition of the engine. Did you do a compression check? Check all the stuff that's been mentioned above, you are way below typical RV-3 speeds with an O-320. You should almost touch Vne with that engine.

We've got a RV-3 with an 115 hp O-235 and get ~145 kts at WOT. Ed Sterba prop 68*64.

Hi Simon,
yes I bought that RV3.
There are several checks to be done but finally the engine turns at a speed that should be enough to go much faster with the Ed Sterba 68x74.
ASAP I will check compression (that looks high rotating the engine), timing and carburetor. The engine runs fine and smooth, no oil consumption in the first 6 hours of flight neither smoke or oil fuselage deposits
I removed the carbon look film and gained some knots, but still low speed.
Thank you for your comment.
 
Thanks, I didn't understand what the Speed demon data was. So, speeds truly are low, so not an indication issue though he didn't share what RPM produced that data. That leaves drag. He has pretty much the same size prop as the other RV3 poster, yet getting substantially slower speed at the same RPM. That takes engine performance off the table and leaves us with drag or some other aerodynamic issue that explains the differences IMHO. Though I suppose there could be some type of flaw with the propeller affecting performance. The same plane with the same sized prop spinning at the same RPM should produce reasonably similar airspeeds at level cruise, at least for fixed pitch props. CS props are a different animal. It could also be that the RPM reported to the pilot is not the same as the actual RPM of the propeller, in which case that data is irrelevant. If he thinks the prop is spinning 2500, but really spinning 2100 then we are back to engine performance issues.

If it were me, I would get some type of strobe based RPM reader to confirm the RPM indication; Probably $25 on amazon. Most of us can feel and hear the RPM, but wouldn't expect a brand new plane owner to be able to do that.

Larry
Larry this is a good point, in level flight full throttle is around 2540 indicated. I will follow your suggestion and buy a strobe, then check also this.
The data are coming from Skydemon that is a gps application similar to foreflight. It records speed and altitude but not climbing rate nor RPM.
Propeller is a Ed Sterba 68x74.
What about the way to check flaps zero angle (retracted flaps)? I haven't found a precise rigging procedure on drawings/documents
 
This is what Gustavo has been doing by using the very popular, in Europe, navigation app SkyDemon.
Looking at his flight, though not flown on a triangular or quadrangular course, it reflects the low speeds he is reporting. Ok, he had a climb during that flight.

Was that flight flown at WOT (Wide Open Throttle), is the arm hitting the max travel stop on either the carb or throttle body?
The prop RPMs look ok to me, but for not being able to reach 2700RPM full power. What about the RPM in a WOT descent?
Hi Dan,
I didn't check descent at WOT, that flight was to check trimming after having placed a rudder trim tab to correct bank.
I will check this weekend the throttle opening at full forward position. According to the builder this was checked, but when I bought this aircraft it had flown 30 minutes only so I am still in a trouble shooting phase and I can't be sure of nothing up until it is checked again.
I didn't fly the four directions but that day there was almost no wind, so TAS=GPS speed or very close
Thank you for your message
 
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Larry this is a good point, in level flight full throttle is around 2540 indicated. I will follow your suggestion and buy a strobe, then check also this.
The data are coming from Skydemon that is a gps application similar to foreflight. It records speed and altitude but not climbing rate nor RPM.
Propeller is a Ed Sterba 68x74.
What about the way to check flaps zero angle (retracted flaps)? I haven't found a precise rigging procedure on drawings/documents

Assuming this wing is like the 4/6/8 wings, which I believe it is, pull the wing tip. You will find two 3/16 or 1/4" tooling holes in the center area of the outer wing rib. Align a straight edge with the centers of these two holes. That straight edge should intersect the center of the aileron and flap trailing edges for a neutral position. Both ailerons should be neutral at the same time / stick position. Be sure to have the elevator held neutral with a clamp of some sort while making these measurements, as other positions change the aileron throw due to the geometry of the stick pivot mechanism. Be sure to check ailerons and flaps for twist (i.e. trailing edge not straight in there longitudinal axis relative to a line between the two hinge / attach holes or the wings longitudinal surface plane). If they have twist, try to find an average point to set neutral so that there is an equal amount up and down from neutral. DO NOT use the wing tip TE as neutral. You have no idea if it matches neutral.

With the flap, you want to pull up a bit on it to take out the slack when setting neutral, as that is what the airflow over it at speed will do. Ailerons use bearings, so no slack to remove.

Larry
 
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Assuming this wing is like the 4/6/8 wings, pull the wing tip. You will find two 3/16 or 1/4" tooling holes in the center area of the outer wing rib. Align a straight edge with the centers of these two holes. That straight edge should intersect the center of the aileron and flap trailing edges for a neutral position. Both ailerons should be neutral at the same time / stick position. Be sure to have the elevator held neutral while making these measurements. Be sure to check ailerons and flaps for twist (i.e. not straight). If they have twist, try to find and average to set neutral.

Larry

Thank you Larry!
 
0320 powered RV-4

For comparison: My original engine on my 4 was an 0-320-E2D upgraded to 8.5-1 compression ratio with a Sterba 68x68 prop. Ed recommended a 68 x 68 for my E2D not knowing that it been upgraded to 160 hp.

This prop would static 2650 rpm so obviously was under pitched but would run 190 mph all day long at 2800 RPM. With a new Warnke wood prop tailored to my combination I would cruise at 190 mph @ 2600 rpm with a top speed of 210 mph at 2750 rpm.

You have the wrong prop and should be returned to Ed Sterba for a re-pitch. He used to include one free re-pitch in his price but that was 20 years ago !

I would recommend changing to the 8.5-1 (160 hp) pistons possible as the extra 10 hp makes a bid difference on a light plane like your 3 as well as improves the engines efficiency burning approx. 1 GPH less and will still work with ethanol free auto gas.

Once you get your engine matched to the right prop I'm confident you'll be much happier with its performance.
 
Just thought that I would add my $.02 in on this since I am a -3 driver. Mine has the O320-E2D 160hp, and I also fly the same Sterba prop. Static rpm is 2,250, in the air WOT no more than 2,550rpm. With that I see 190mph. Normal cruise is at 2,300, which will give me a steady 170mph. I did have a problem with my tach 2 years ago, in that it was reading high, in that idle was reading 1,200rpm. As it has been suggested, I would and check that your throttle might not be opening up all the way. And quite possibly your tach is reading wrong.
 
Speed numbers

I have two Prince P-tip (68”x76” and 68”x79”) that I’ve tested on my RV3B with O-320 160hp. I tested the 76” prop at 6,500’ and 11,500’ and the speeds were the exact same, I kid you not. The only difference was fuel burn which was 0.7 - 0.8 gph less at 11,500’. After plotting the data I determined at the same fuel burn the 79” prop was 4 kts faster. For 2600 rpm or less I would pull the mixture back til a slight stumble and richen it up a little

The speed numbers below are at the following parameters for each prop below
At 6,500’ 60 deg F, Baro = 30.24 (76” pitch prop)
At 6,500’ 62 deg F, Baro = 30.04 (79” pitch prop)

Speeds below are in TAS in knots
RPM. .pitch 76” …pitch 79”
2300 .. 139. ……….. 150
2400 .. 146. …….... 157
2500 .. 153. ………. 163
2600 .. 159. …….... 171
2690 …….. ………….. 177 WOT
2830 .. 167 WOT
 
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For comparison: My original engine on my 4 was an 0-320-E2D upgraded to 8.5-1 compression ratio with a Sterba 68x68 prop. Ed recommended a 68 x 68 for my E2D not knowing that it been upgraded to 160 hp.

This prop would static 2650 rpm so obviously was under pitched but would run 190 mph all day long at 2800 RPM. With a new Warnke wood prop tailored to my combination I would cruise at 190 mph @ 2600 rpm with a top speed of 210 mph at 2750 rpm.

You have the wrong prop and should be returned to Ed Sterba for a re-pitch. He used to include one free re-pitch in his price but that was 20 years ago !

I would recommend changing to the 8.5-1 (160 hp) pistons possible as the extra 10 hp makes a bid difference on a light plane like your 3 as well as improves the engines efficiency burning approx. 1 GPH less and will still work with ethanol free auto gas.

Once you get your engine matched to the right prop I'm confident you'll be much happier with its performance.

Thank you for your comment!
 
Just thought that I would add my $.02 in on this since I am a -3 driver. Mine has the O320-E2D 160hp, and I also fly the same Sterba prop. Static rpm is 2,250, in the air WOT no more than 2,550rpm. With that I see 190mph. Normal cruise is at 2,300, which will give me a steady 170mph. I did have a problem with my tach 2 years ago, in that it was reading high, in that idle was reading 1,200rpm. As it has been suggested, I would and check that your throttle might not be opening up all the way. And quite possibly your tach is reading wrong.

Hi Tad,
thank you for your message. Do you fly a 68x74 Sterba prop? I will check the RPM, just ordered on Amazon a strobo instrument. Ed Sterba is out of the business now, so no chance to repitch.
 
I have two Prince P-tip (68”x76” and 68”x79”) that I’ve tested on my RV3B with O-320 160hp. I tested the 76” prop at 6,500’ and 11,500’ and the speeds were the exact same, I kid you not. The only difference was fuel burn which was 0.7 - 0.8 gph less at 11,500’. After plotting the data I determined at the same fuel burn the 79” prop was 4 kts faster. For 2600 rpm or less I would pull the mixture back til a slight stumble and richen it up a little

The speed numbers below are at the following parameters for each prop below
At 6,500’ 60 deg F, Baro = 30.24 (76” pitch prop)
At 6,500’ 62 deg F, Baro = 30.04 (79” pitch prop)

RPM. ..Kts (76”) ……Kts (79”)
2300 .. 139. ………. 150
2400 .. 146. …….... 157
2500 .. 153. ………. 163
2600 .. 159. …….... 171
2690 …….. ………….. 177 WOT
2830 .. 167 WOT

Thank you for the useful data!
 
Just thought that I would add my $.02 in on this since I am a -3 driver. Mine has the O320-E2D 160hp, and I also fly the same Sterba prop. Static rpm is 2,250, in the air WOT no more than 2,550rpm. With that I see 190mph. Normal cruise is at 2,300, which will give me a steady 170mph. I did have a problem with my tach 2 years ago, in that it was reading high, in that idle was reading 1,200rpm. As it has been suggested, I would and check that your throttle might not be opening up all the way. And quite possibly your tach is reading wrong.

Great comparison data. Same plane, same prop. With this comparison data, engine issues are somewhat irrelevant as similar RPM's should net similar TAS's. This guy is getting 165 Knots at 2550 and you are getting 130. That is an awfully big difference, so my money is on an erroneous RPM indication, as I don't see how drag can be this bad without visually noticing the flaws.

If the RPM is much lower than the indicated, there may be some work to figure out why the engine is so low on power. Did you ever confirm full throttle and mixture throw? Once you get to diagnostic mode, it will be helpfull to have a fuel flow indication. It might make sense to take your down time and calibrate the fuel flow instrument and add a MAP gauge. You can add a restrictor to the end of the fuel line going to the carb. Then measure the time it takes to fill a measured amount of fuel with the boost pump and do some math. Eventually you will get it close.

The one thing that doesn't add up at all here is the fact that both you and this poster get very similar static RPM readings, implying that you are getting accurate RPM indication. I struggle to resolve the fact that the static readings match in RPM, yet the air speed at similar RPMs are so far off. If the RPM indication is truly reading high, you will then need to figure out why the static RPM is so low - low engine output is top of that list. If the RPMs indicated are accurate, as this implies, then we are pretty much back to drag. Let use know what you find on the rigging.

Larry
 
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Trim?

How much trim do you have on the elevator in cruise flight? A picture of the elevator in cruise will show that.

Reason? It is possible the angle of incidence of the horizontal stabilizer is set incorrectly. In that case you need to trim the elevator more than normal to compensate. You end up with the HS pushing one way and the Elevator pushing the other way... and that's not efficient. We are talking a 3 model here, and so it's easy for this to have been set wrong.

I'm not expecting 10 Knots out of this, but it could be a factor.

Regarding the Tach... is it mechanical or electronic? More likely to be reading wrong if mechanical.
 
Larry, Blaplante,
all your considerations are valuable and probably next Sunday we will have some responses, at least on engine performances.
I don't have a picture of the trim, all what I can say is that after landing the tab is well aligned to the elevator: this means that in flight it stays up to generate a bit of nose down, may be to compensate my weight (215 Lbs dressed).
Here attached a picture of the current panel, you will notice two air speed indicators (pneumatic and electronic) and one electronic tach.
2540 is obtained full throttle and full rich.
 
Not a fan of using tooling holes

What about the way to check flaps zero angle (retracted flaps)? I haven't found a precise rigging procedure on drawings/documents

I recommend ordering the wing template from Vans. It is a full scale print out of the wing profile, including ailerons and flaps. You then trace it on a piece of particle board, plywood or other board using carbon paper. Then cut out the inside (and very thin cuts at each end so you can fit it over the wing.

Great way to check flap, aileron and wing tip alignment.

If someone has that in CAD format they can send to you and you can get it locally printed accurately, that would of course be faster.

Finn

P.S. I understand that the wing kit crate comes with it printed on one of the sides?
 
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I recommend ordering the wing template from Vans. It is a full scale print out of the wing profile, including ailerons and flaps. You then trace it on a piece of particle board, plywood or other board using carbon paper. Then cut out the inside (and very thin cuts at each end so you can fit it over the wing.

Great way to check flap, aileron and wing tip alignment.

If someone has that in CAD format they can send to you and you can get it locally printed accurately, that would of course be faster.

Finn

P.S. I understand that the wing kit crate comes with it printed on one of the sides?
Good Idea, I should have all of them, this evening I will check.
 
I recommend ordering the wing template from Vans....I understand that the wing kit crate comes with it printed on one of the sides?

My 2012 kit for my B model wings did not have it. Here's SK30:

SK 30.jpg

If you remove a wingtip, you can make a full-size template from the wing itself.

Dave
 
My 2012 kit for my B model wings did not have it. Here's SK30:

View attachment 33951

If you remove a wingtip, you can make a full-size template from the wing itself.

Dave

How? Won't give flap/aileron part of profile, which is what we're after here. Back to using tooling holes which I found unreliable. Do not understand why Vans stopped profile drawing on crate.

There's been endless discussions on ailerons and flap alignments. All solved by accurate complete profile, as in SK30 you referenced. So we have SK30, but how does one accurately scale and print it full size?

Wonder what the X+1" is for. Wing incidence?

Finn
 
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Fair the top and bottom surfaces to the aileron, using batten strips if necessary. Then you can line up a board to the wing with the aileron in its place. Confirm.

Cut out the template.

On mine, I made the top and bottom separately and hinged then at the front end. Made it easier to move around and I glued strips of carpet to the inside edge of the template so I wouldn't mark up the wing.

Dave
 
My point is that having the accurate template will detect any number of errors:

Incorrectly bent rear spar flanges, reversed aileron ribs, misdrilled aileron brackets, etc. etc.

Having the guy remove wing tips if pop riveted on just does not make sense (unless the template shows misaligned wingtip trailing edges).

Actually in this day and age it would be disappointing if Vans did not have CAD (CAM) files in various formats that could be sent to sign shops that waterjet or lazer cut poster board.

Scott?

Finn
 
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Isn't the RV3 profile a plain and simple unmodified NACA 23012? I bet a quick google will get you a bunch of hits on that one
 
I think the airfoil is 13.5% thick but am not sure.

My earlier advice to make a template isn't real good. Better would just be to put thin battens on the top and bottom of the wing and use them to assess the control surfaces.

Dave
 
I think the airfoil is 13.5% thick but am not sure.

Dave

The -4 (and 6, 7 and 8) indeed use the 13.5%, but I believe the 3 has a 12% thick airfoil (this is also what the Wikipedia RV3 page states, though I've seen mentioning otherwise as well)

With measuring the spar thickness should not be too hard to confirm or deny...
 
Yes I do have a flow meter, but needs a set up while it is reading values from 24 to 30 GPH... At least there is a correlation between the leaning and the GPH that makes sense.My impression is that the fuel flow works fine, I tried to lean and I can reduce fuel up to 50% before having the typical leaning vibrations or sensible power loss. The air filter looks clean... I am curious to see if the carburetor valve opens to full or if there is a limitation. The average fuel burn is around 8,5 GPH on a 6 hours trip back, average speed was depressing (123 KTS...)

Some good news about my RV-3: today I had a ferry flight to another airport where a friend of mine is going to check the battery charging system. The last two weeks the few hours dedicated to my airplane were to remove the carbon looking film, at this purpose I removed the wheel and leg fairings, so I flew WITHOUT fairings. Temperature was 10°C and QNH 1018mb, level flight at 1050 ft no wind. I surprisingly got 2600 rpm and 153 KTS of TAS! This number makes sense, I guess the root cause for the low speed was probably the wrong angle of attack of the fairings.
In the incoming weeks the RV-3 will be painted, I will add the wood or aluminum stiffeners on the landing gear legs and spend time to properly mount the fairings.
All the checks on carburetor and rigging did not show problems, still need to check mag timing. I bought a very cheap laser tachometer on Amazon, may be too cheap while it didn't work...
 
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