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RV-10TDI Update

Flandy10

Well Known Member
Flight testing has been proceeding VERY SLOWLY- currently at 10.6 hours.

Why? similar reasons it took almost 9yrs to build. LIFE-work/ weather/moving to a new house and now I can blame the USPS.

This engine that I have is a preproduction engine that doesn't "conform" to any type certificate. It is a "C" model with a few changes- Type Certificate is on FAA Website if your interested. As such, CMI is watching it closely (wouldn't you?) via engine data analysis and oil samples. USPS misplaced two separate Blackstone oil samples from 8 to 16 days before delivering them and each report was needed prior to resuming flight testing- that was the entire month of FEB gone.

March was lost due to work (airline pilots having lots of time off is a MYTH-wanna see my schedule) and resealing BOTH fuel tanks. What?:eek: RV-10 builders--The fuel tank stiffeners forward of the spar shouldn't be used as a place to step- if you knew that already, good for you. I had the same three rivets on both tanks start leaking and if you saw my proseal work you too would wonder how that happened.

So, here is what I can tell you about it so far.

It is an air-cooled 304 cubic inch turbocharged diesel cycle engine (no-#2Diesel is not currently an approved fuel like the CD-135 in the Twinstar). 230HP from SL to about 10000 and then drops off to 170HP at 20K. Max TO fuel flow is about 12.5GPH. Working on a more accurate FF measurement system as current aviation version is unable to read it at idle(+/- 9GPH) and significantly off (1-2GPH) at cruise pwr. If you understand the old school Bosch system, you'll understand why. The only real world burn numbers I have right now are one hour at 154 KIAS at 4K below ATL Class B. That flight only took 8 gallons from the JetA truck to top off. I'd been limited to "gliding distance of a runway" for the first few hours so that flight was at max cruise to continue break-in and check CHT and oil temps. Both of which I am happy to report are in a comfortable range for current conditions.

Hot or Cold (engine or OAT), it starts very quickly. The only preflight check is to exercise the prop and wait for the oil to meet min. flight temp.-150F-which doesn't take very long in GA.

Looking forward to roaming my Phase 1 box.
 
Bob,

Numbers from the G3X file were 154KIAS/163KTAS 8*C 78"MAP.

FF read 8.7 GPH but due to instability in the meter readings, I know that is not right. 90% power (max cruise) calculates out to be 10.9GPH. The fuel truck read 8 gallons when topping off after flight.
 
Scott, thank you for posting the update! Exciting news for sure. I'm staying tuned for pictures / updates in the future.
 
Good luck Scott and keep the reports coming!

May I suggest that the next time you take an oil sample, take two (or three), send one off and put the other sample on your shelf, just in case.
 
Any Photos of the installation?

A few views under the cowl, would be great if and when you have the time or inclination. Congratulations on all the time and work done.
 
Flight testing has been proceeding VERY SLOWLY- currently at 10.6 hours.

This engine that I have is a preproduction engine that doesn't "conform" to any type certificate. It is a "C" model with a few changes- Type Certificate is on FAA Website if your interested. As such, CMI is watching it closely (wouldn't you?) via engine data analysis and oil samples.

Take your time, do it right. With you, I think they made a good pick all around.

Group; Continental is sincerely concerned about a bad EAB installation giving them a black eye, when the diesel program is doing rather well on the certified side. Can't blame 'em at all. Let's let Scott do his thing at a deliberate pace, and we'll all get there eventually.
 
Good going, Scott! Sounds like great performance. I look forward to hearing more. Soon as you get all the bugs worked out, I'll be ready for one!

Kurt
RV9 WAM diesel 560 hours
Sportsman CD-155 diesel 380 hours
 
Here are a few pictures of the installation.

iqetxs.jpg


174fmt.jpg


24q6zcg.jpg
 
pictures

Thanks Scott - looks really cool - if you want to post 100 pictures I'm sure we'd all love to see them.
 
YES YES YES!!!

I've been eyeing a VW 3.0 V6 TDI for the powerplant if / when I get to build an RV-10.

I'm very interested in this project!
 
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Performance Data

With the G3x fixed, its time to finish Phase 1.

Fuel Consumption testing flight #1: 5500ft at Max Cruise (90%- 207HP) approx. pwr

105kt cruise climb to 5500,
30min. at 76"MAP 2190rpm 151Kias/167Ktas
60"MAP descent at 155 Kias. 750fpm

Instruction to lineman- 1 inch from the top before flight and after.

Dipstick readings----- L tank ---- R tank (these are not gallons)
Before ------------------- 13.0 ---- 13.0
After --------------------- 9.5 ------ 10.5
After refuel -------------- 13.5 ---- 13.0

G3x recording length 58 minutes and 7.1 Gallons. Airborne 45 minutes.
Fuel truck--7.0 gallons


Qualifier:Red Cube calibration still being adjusted. Due to fuel injector pulses, red cube can't read ground fuel burn, so fuel counter reset just before takeoff. But I forgot to check it just after landing, so while it looks real accurate, its not. I just got lucky. But the fuel truck meter is accurate:)
 
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Sorry, I just can't get used to seeing 60" MAP in a descent! :)

Those numbers look very encouraging. And if I may say so, the photos of your installation make it look very neat and tidy. I wish you the very best of success in this endeavor.
 
Appreciate the update Scott. Looking forward to more FF and speed data as you get it. This has to be one of the most interesting RV10s flying. :)
 
Appreciate the update Scott. Looking forward to more FF and speed data as you get it. This has to be one of the most interesting RV10s flying. :)

I'd say.

Ballpark price on this engine so I'll know if it's even in the realm of possibility over here?
 
Someone smashed your lower cowling :D

Like to see more pictures of the cowling work that was required.
 
Cowling Modification

So, how do you take a standard Van's cowl and transform it into something that will work with a turbo charged, intercooled diesel. Have you got 8 months-:rolleyes: Lets start with the new requirements- 15 inch spinner, intercooler, oil cooler 2.5 times standard size, and others.

Start with the spinner change.
i-g5CcxTW-M.jpg


Another reason for the spread, this high pressure fuel line (5,000psi+) made contact with the original cowling
i-PkDdqmZ-M.jpg
Not anymore:D

Repeat with bottom cowl and throw in a large amount of expanding foam- fun stuff
i-q35VWMn-M.jpg


Shape
i-zWzwTXs-M.jpg


Glass
i-3Z2w3SM-M.jpg


Remove old lower section and graft on new
i-7QmMJ7N-M.jpg


And that's just the beginning.....
 
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I'm jealous! Can't wait to hear more. It has been a lot of work, but someone's gotta do it!

Kurt
 
Here are a few pictures of the installation.

174fmt.jpg


24q6zcg.jpg

I'm assuming one of these is the oil cooler, the other is the intercooler? Any problems on either with such a huge divergent opening of the plenums?

I'm a big fan of the potential for diesel... really cheering for you on this one (because I want to plagiarize it).
 
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The intercooler is on the right and the oil cooler is on the left.

The ducting is working pretty well, but with anything, there is room for improvement during the hot summer days.
 
More Performance Numbers

G3x recorded 1:47 total time. I figured airborne 1:34 and total burn per the truck meter---12 gallons. Back on level ground in hangar, I sticked the tanks to verify fillup- needed another .5 gallon in one tank. So--12.5 total burn. Fuel burn at 12500 was between 7.5 and 8.0 GPH

Flight profile--climb to 5500 till clear of Class B then continue to 12500. 30 min max cruise. Decided on way down to stop every thousand to check speed numbers.

The following numbers were taken from the data file- let speed stabilize and eyeballed an average- Not the fastest and not the slowest--trying to be honest with the numbers.

Altitude ----IAS ---- TAS ---MAP
12500------127----157-----57
10500------128----154-----60
9500-------135-----158-----60
8500-------136-----158-----60
7500-------132-----151----61
6500-------135-----151----61
5500-------151-----167----76
4500-------155----168-----76


Why the big increase in MAP below 6500? The short version is ----The turbo on this pre-production engine didn't come with a speed sensor (and no way to retrofit one either). So to allow operations above 6000, CMI felt it was prudent to limit the MAP to the "B" model power numbers to prevent overspeeding the turbine.

There is one more test planned---side by side flight with a standard -10 to compare performance numbers.
 
G3x recorded 1:47 total time. I figured airborne 1:34 and total burn per the truck meter---12 gallons. Back on level ground in hangar, I sticked the tanks to verify fillup- needed another .5 gallon in one tank. So--12.5 total burn. Fuel burn at 12500 was between 7.5 and 8.0 GPH

Flight profile--climb to 5500 till clear of Class B then continue to 12500. 30 min max cruise. Decided on way down to stop every thousand to check speed numbers.

The following numbers were taken from the data file- let speed stabilize and eyeballed an average- Not the fastest and not the slowest--trying to be honest with the numbers.

Altitude ----IAS ---- TAS ---MAP
12500------127----157-----57
10500------128----154-----60
9500-------135-----158-----60
8500-------136-----158-----60
7500-------132-----151----61
6500-------135-----151----61
5500-------151-----167----76
4500-------155----168-----76


Why the big increase in MAP below 6500? The short version is ----The turbo on this pre-production engine didn't come with a speed sensor (and no way to retrofit one either). So to allow operations above 6000, CMI felt it was prudent to limit the MAP to the "B" model power numbers to prevent overspeeding the turbine.

There is one more test planned---side by side flight with a standard -10 to compare performance numbers.

Looks like pretty good total burn for that mission profile. Around 25-30% lower volume burn per hour in cruise against a well sorted injected 9 to 1 CR Lyc 540 running LOP with EIs. About 12-15% lower burn per unit fuel weight.

Most reports seem to show 9.5-12 gph LOP on injected 540s, depending on power settings but I'd invite any RV10 guys to weigh in with your numbers for comparison.

In cruise at least, a solid $15+/hr. cost savings using the average prices here: http://www.airnav.com/fuel/report.html Jet vs. 100LL.

The side by side will show the true fuel cost delta for for the complete mission. That will be very interesting. Hopefully you'll be comparing with an injected Lycoming with EIs running LOP, not a carbed one running ROP...

I'm curious as to what sort of fuel burn and MAP you're seeing in the descent?

I appreciate the amount of work that went into the installation. Kudos there. Cool project!
 
Descent planning

Ross,

On this flight, I just maintained the cruise power and set up a 750fpm descent. From 12500 down to 6000, those MP settings equate to about 155-160Kias descent. I'm going to make a guess that with fuel flow for 57"MP at about 8gph, it is approaching 8.5 at 62"MP. Again, just a guess.

The ability to accurately measure FF over the entire RPM range has been an exercise in futility. The Red cube system cannot read the idle flow rates (I see 2.5 to 45gph :eek: regularly during taxi- it should be >.5gph) and its inflight variation can be +/- .5 to 1 gph at any given second. So I'm looking for a K-factor that comes close. I have looked at other systems that work accurately with diesel generators or boats, but nothing is compatible with aviation's analog inputs.
 
Ross,

On this flight, I just maintained the cruise power and set up a 750fpm descent. From 12500 down to 6000, those MP settings equate to about 155-160Kias descent. I'm going to make a guess that with fuel flow for 57"MP at about 8gph, it is approaching 8.5 at 62"MP. Again, just a guess.

The ability to accurately measure FF over the entire RPM range has been an exercise in futility. The Red cube system cannot read the idle flow rates (I see 2.5 to 45gph :eek: regularly during taxi- it should be >.5gph) and its inflight variation can be +/- .5 to 1 gph at any given second. So I'm looking for a K-factor that comes close. I have looked at other systems that work accurately with diesel generators or boats, but nothing is compatible with aviation's analog inputs.

Interesting. Surprised at such high MAP in the descent. Certainly different from a turbo SI engine. Is there a minimum MAP they recommend in flight to keep the fires lit?

They don't have any FF signal available out of the FADEC?
 
Hi Scott,

Have you looked at the older style FloScan sensors? They make them specifically for diesel engines (marine), and as far as I know, their K factor is similar to the gas version. Therefore, they should work with your gauge/EFIS, since (again, as far as I know), the FloScan & red cube sensors are supposed to interchange.

Just a thought,

Charlie
http://www.floscan.com/dnloads/floscanfinal.pdf
 
Interesting. Surprised at such high MAP in the descent. Certainly different from a turbo SI engine. Is there a minimum MAP they recommend in flight to keep the fires lit?

They don't have any FF signal available out of the FADEC?

Remember, takeoff power is 83 to 90" depending on conditions, so 60" really isn't that high. They do recommend 30-45" MAP depending on OAT to insure auto ignition. I can tell you I have never seen it below 31" even at low idle on the ground.

This engine has no FADEC. Straight mechanical fuel injection unlike the CD-135/155 and no servo control function like its SMA cousin.
 
Hi Scott,

Have you looked at the older style FloScan sensors? They make them specifically for diesel engines (marine), and as far as I know, their K factor is similar to the gas version. Therefore, they should work with your gauge/EFIS, since (again, as far as I know), the FloScan & red cube sensors are supposed to interchange.

Just a thought,

Charlie
http://www.floscan.com/dnloads/floscanfinal.pdf

Charlie,

I actually called the folks at FloScan to talk with them about their diesel systems. The engineer couldn't hang up the phone fast enough when I explained what type engine I was using.:eek: It didn't matter that it would be a certified aircraft engine.

Most marine diesel FF meters that would work speak DIGITAL and aviation displays speak ANALOG. The problem aviation version of the FloScan and Red Cube have are that the Bosch mechanical injector pump introduces 3200 pulses/minute(idle) and 8800 pulses/minute(flight) into the incoming fuel stream. Think shockwaves or instantaneous microstops to the incoming fuel. This drives the turbine meter systems nuts. And yes I've looked into digital to analog convertors. I've yet to find one that can work with the few number of pulses per gallon the system would produce at idle. I actually found a system that was designed to account for these pulses, but again, its output was digital.

I knew when I committed to installing this engine, I would be on the cutting edge. I just didn't think I would be the FIRST one, I expected an OEM to get there first.
 
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Hmmm...I always thought that the FloScans & red cubes output pulses, with the K factor related to how many pulses per gallon (or pound; whatever).

Oh, well.
 
I wrongly assumed this engine used a FADEC with backup mechanical system like the SMA engine. Thanks for the correction.
 
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Pulse Damper

Scott,
Would a pulse damper (or two in series) between the FloScan sensor and the injector pump isolate the sensor from the pulses?

Cheers, David
RV-6A KBTF
 
Hmmm...I always thought that the FloScans & red cubes output pulses, with the K factor related to how many pulses per gallon (or pound; whatever).

Oh, well.


Charlie,

You understand them correctly. In fact, I verified the fuel flow of the duplex (supply and return) cube system prior to getting the engine. Its the injector pulses that introduce a stutter to the incoming fuel stream causing the flow through the cube to be jumpy. Its still flowing 48gph, just not a smooth flow that the turbine meters like.
 
Scott,
Would a pulse damper (or two in series) between the FloScan sensor and the injector pump isolate the sensor from the pulses?

Cheers, David
RV-6A KBTF

I was told, in France, they did some testing and found it took 3 spherical pulse dampeners to isolate the sensor. This was on a C182 with the SMA engine which has no return flow system. There is no room in the tunnel or under the cowl for that mess.

I am still in search of a better solution to this problem.
 
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I was told, in France, they did some testing and found it took 3 spherical pulse dampeners to isolate the sensor. This was on a C182 with the SMA engine which has no return flow system. There is no room in the tunnel or under the cowl for that mess.

I am still in search of a better solution to this problem.

What did Cessna use on the 172 and 182 diesels?

Not an elegant solution but what about wiring an on/off switch into the redcube? Turn it on as part of your takeoff check list... You know the fuel flow on the ground, anything short of an hour to taxi/takeoff is barely a rounding error for most top offs. Remember back in the day when you did it off the POH and then went to the fuel truck after a long flight to see if your math was accurate? :D

Tried talking to the EFIS manufacturers to see if there's a solution to using a digital box?
 
To me a fuel totalizer is making up for bad fuel tank measurements. Would it not be easier to fix the problem of the fuel tank measurements then add one more bandaid?

Tim
 
To me a fuel totalizer is making up for bad fuel tank measurements. Would it not be easier to fix the problem of the fuel tank measurements then add one more bandaid?

Tim

Right. And a GPS is just one more bandaid for poor pilotage.

;-)
 
Its the injector pulses that introduce a stutter to the incoming fuel stream causing the flow through the cube to be jumpy. Its still flowing 48gph, just not a smooth flow that the turbine meters like.

Below, red cube rotor, and the cover plate with what appears to be an optical sensor.

The rotor is some sort of plastic, very low mass, probably so it is easy on the bearings in a vibrating environment. System seems to work by breaking the light beam, so if the rotor reverses just a tiny bit due to a pulse, the count goes up.

 
And....That's why I suggested a diesel FloScan sensor. They all appear to work the same way, but the ones made for diesel marine engines seem to work OK. It would make one wonder whether FloScan did something like add mass to the turbine wheel to make it less sensitive to pump impulses. Is there a fundamental difference in the fuel delivery system of a typical marine diesel & the one in the a/c?

At any rate, there are often diesel FloScan sensors available on ebay for cheap. Electrically, it should hook right up to the existing electronics in the a/c. In the overall cost bucket, a diesel sensor & a couple of pressure dampers should be a cheap experiment. The dampers are easy to make, with extra plumbing fittings.

Or maybe I'm off in the weeds, and diesel boat drivers don't worry about low load/rpm errors.

Charlie
 
The 172 (CD-155) uses the FADEC supplied fuel flow number and the canceled C182JTA (SMA 305) used a derived FF from the servo control computer (I asked after searching the Cessna parts manuals and finding no FF meter). None of the SMA STCd C182s actually measures the FF except for the tests I mentioned.

As for the G3x reading digital, that would take a hardware redesign. Tim/Mike/John (TEAM X) have been extremely helpful as I've worked through some of the differences the EMS required.
 
And....That's why I suggested a diesel FloScan sensor. They all appear to work the same way, but the ones made for diesel marine engines seem to work OK. It would make one wonder whether FloScan did something like add mass to the turbine wheel to make it less sensitive to pump impulses. Is there a fundamental difference in the fuel delivery system of a typical marine diesel & the one in the a/c?

Charlie,

I believe the FloScan sensors are identical for both boats and planes. The difference is the diesel systems add the canister that looks like an oil filter. It is a flow homogenizer/ pulse dampener- that's the key to making this work. I will admit I totally forgot about looking on Ebay.

The biggest problem with these systems is WEIGHT. The transducers weigh 10 ozs but the rest of the marine equipment adds up. And yes, I plan on doing more testing of different ideas- I've not given up yet, just running out of calendar days before OSH.

I appreciate ALL the ideas people have put forward, keeps me thinking about alternatives.
 
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Right. And a GPS is just one more bandaid for poor pilotage.

;-)


No. GPS is a fundamental change in how you navigate in a radio based environment. (pilotage is not the correct comparison, VOR and NDB are).
In this case a fuelntotalizer and a fuel tank gauge are providing the same service. How much fuel is remaining. Fuel totalizers largely came about because of inaccurate fual gauges. Fuel gauges have historically been inaccurate because of FAA lighting and other requirements constrained possible solutions. We do not face such constraints. So why continue with the bandaids?

Tim
 
So...

How do you propose we deal with fuel gauges then? For example, in the RV-10, the fuel gauge senders cannot read accurately above a certain amount due to the dihedral in the wing...consequently, the tank will read Full until it reaches a point where it can measure accurately.

The totalizer will tell you exactly how much you have used and what is left in the tank from top off to empty.

I know you will say that you would rather be accurate on the bottom than the top, and I agree with you.

I guess I would prefer to have both quantity and flow, if possible...
 
The totalizer also can give you estimated fuel left at destination when tied into your GPS (assuming it's calibrated correctly) which greatly assists in making the decision about a fuel stop or push on.
 
How do you propose we deal with fuel gauges then? For example, in the RV-10, the fuel gauge senders cannot read accurately above a certain amount due to the dihedral in the wing...consequently, the tank will read Full until it reaches a point where it can measure accurately.

The totalizer will tell you exactly how much you have used and what is left in the tank from top off to empty.

I know you will say that you would rather be accurate on the bottom than the top, and I agree with you.

I guess I would prefer to have both quantity and flow, if possible...

The way boats deal with it. Two senders, one at each end or the tank. Then draw a line between and determine capacity or measure as you fill.

Tim
 
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