What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

WAM-120 Diesel RV-9A first flight

Dave_Boxall

Well Known Member
We flew our RV-9a fitted with the WAM-120 engine today. First impressions very good. Cooling is fine. Pictures on the RV-9/9a section - "show us a picture of your finished RV-9/9a"

Not the fastest RV ever, but certainly cheap to run.

I love the smell of jet fuel in the morning....


Dave

[ed. Here are those pics (from the other post). dr]

DSC02208.jpg


FirstFlight004.jpg


FirstFlight006.jpg
 
Last edited by a moderator:
Congrats - while DeltaHawk is still showing the same old lame drawings, WAM seems to be actually delivering!
 
Good Job!

Great job guys. Must have been a ton of extra work with a non standard engine. We'll be very interested in your numbers when you get around to posting them.
Of course, you'll have to behave yourselves since you are so recognisable.
 
Congrats Dave! Looking forward to more performance numbers down the road especially at altitude with the turbo.
 
Good deal Dave

As an Expat Brit (I Did Mechanical Engineering at Bath University) I can feel the pain at the pumps where 80% of a gallon of fuel is tax!!!

Like everyone else I ran diesel cars and loved them.

Good for you!

Frank
 
Just a tip though

Get that nose gear OFF the ground ASAP on the TO run and don't let it touch on landing till as late as possible..Have the stick all the way back st the start of TO and end of landing.

Pretend the NG is made of glass..Cus it pretty much is..:)

We don't want to be reading of a noseover accident!!

Cheers and Say Hi to the Duke of Beaufort for me...I used to skydive at his farm in Badminton many years ago..

Frank
 
This is a real step forward

Its only matter of time until 100LL goes away. Auto fuel is going to have alcohol. I think stopping these things will be like trying to stop gravity.

Motors that run on JetA have a real future and solve a real problem. I don't have the wrenching skills or patience to be one of the pioneers of this activity, so I'm thankful for those that do.

Congratulations Dave for moving this work forward!

I'm hoping that by the time I need an overhaul there are several diesel options out there.
 
It's hard to avoid that "basking shark" look if you use the Wilksch supplied cooling pack. Still it does make us a little different from the other RV-9's

Weight is 473 kg, 1043 lbs. CG 76.9 Inches AOD. We have a Flightline Interior with leather & confor foam seats, no spare space in the panel (though we have the glove-box fitted), a massive battery (Odessey PC925) and an MTV-21 propellor.

The weather is looking good, so I'm hoping to fly off a few more test hours tomorrow!

Dave
 
Dave,

Glad to hear of your safe and successful first flight. I have been following the WAM and your updates with keen interest and have appreciated your posts on the subject. I have a couple of questions for you regarding your installation.

How did you route your fuel return line and what size line did you use? I'm currently getting ready to close up my first tank and want to include a provision for a return line. I have long hoped that a workable diesel solution would come about before I get to the engine stage and I assume that these will generally require a return line.

In a previous posting, you once mentioned that capacitance fuel senders should be used with this installation. Why is this? Wouldn't float senders work fine with any fuel?

Any recent updates on Wilksch? Still the same 1 year old stuff on their website.
 
Last edited:
How did you route your fuel return line and what size line did you use? I'm currently getting ready to close up my first tank and want to include a provision for a return line. I have long hoped that a workable diesel solution would come about before I get to the engine stage and I assume that these will generally require a return line.

In a previous posting, you once mentioned that capacitance fuel senders should be used with this installation. Why is this? Wouldn't float senders work fine with any fuel?

Any recent updates on Wilksch? Still the same 1 year old stuff on their website.

Our return line is -4 aluminum tubing (the same as the tank vent lines). It runs parallel with the main fuel line back through the fuselage and via an Andair dual valve. The line goes back into the tank via a bulkhead fitting in the tank end rib just below the fuel vent fitting. Our return fuel flows were at the low end of the acceptable range, and maybe a -6 line might have been better.

The capacitance sensors are a requirement of the LAA (the regulators for homebuilds in the UK). There is a theoretical explosion risk with jet fuel tanks and we were required either to fit through flow venting or to remove the resistive sensors because of the risk of sparking in the tanks.

Wilksch are developing a "big bore" version of their 3 cylinder engine which will weigh the same, but produce around 145hp. They currently have around a 20 engines flying (we're the 6th RV-9). They've stopped marketing "retail" engines as homebuilders need a ton of support & won't order the volume required to make production economic. I think they're working on getting an airframe manufacturer to install the engine and order some volume.


Dave
 
Eh?

A thoeretical explosion risk with jet fuel and not with say Mogas, using resistive sensors?

Surely kerosene has a higher flash point than petrol does? So why is there an increased risk?

Not sure I understand the comment on the return line being too small?...Does this engine have a fuel injection pump like regular diesels do?..if so the fuel will either go to the return or to the engine..In other words the FI pump will simply increase the pressure to return the fuel to the tank..In other words the return line should be just fine.

Frank
 
Gasoline has a much higher vapor pressure than jet fuel, and will very quickly develop a vapor mix in the tank that is too rich to burn or explode. Jet fuel evaporates more slowly and can, theoretically, form explosive mixtures in the tank. NTSB decided this is what brought down TWA800. Flow-thru venting will keep the mixture too lean to explode.
 
Last edited:
snip

Wilksch are developing a "big bore" version of their 3 cylinder engine which will weigh the same, but produce around 145hp. They currently have around a 20 engines flying (we're the 6th RV-9). They've stopped marketing "retail" engines as homebuilders need a ton of support & won't order the volume required to make production economic. I think they're working on getting an airframe manufacturer to install the engine and order some volume.

snip

This sounds like a winner for the 9. I would question the decision not to market to homebuilders. I wonder if this means that they will refuse to sell to hombuilders, or they are just not actively marketing to them? Don't homebuilders account for at least half of the light airplane production (in the States anyway)?

It would seem they are passing up on a big portion of the market. Seems like it would make sense to identify the most popular homebuilts and try to develop FWF kits for them that would reduce the support requirements. Trying to secure an airframe manufacturer is great, but it puts all your eggs in one basket. Working with homebuilders would seem to reduce the risk of the bottom suddenly dropping out if your one and only client decides not to buy your product anymore or if you can't find that one and only client in the first place. Not to mention that homebuilders could provide a lot of free track record development (assuming successful installations) which would be a selling point for them when approaching an OEM.

I wish them the best, but this choice just doesn't make sense to me. They should be eager to have anyone installing their engines and do their best to ensure that those installations are successful. I guess I'll just keep pounding rivets and wait to see how things develop and hope for something truly modern like this to finally make it to prime time before I need to choose an engine.
 
Last edited:
Gasoline has a much higher vapor pressure than jet fuel, and will very quickly develop a vapor mix in the tank that is too rich to burn or explode. Jet fuel evaporates more slowly and can, theoretically, form explosive mixtures in the tank. NTSB decided this is what brought down TWA800. Flow-thru venting will keep the mixture too lean to explode.

This makes sense. So how does flow-thru venting work? Is fresh air forced into the tank somehow? How do diesel cars deal with this?
 
Last edited:
On a small aircraft flow through venting seems to use one forward facing and one rearward facing tank vent. Air enters the tank via the forward facing vent & leaves through the rearward facing. You arrange the vent ports inside the tank to purge the vapour space.

I don't think Wilksch are planning to abandon the homebuild market, but making 20 engines a year for homebuilders isn't economic and expanding sales to several hundred engines is a big step up.

Dave
 
We have some better numbers now.
We have a total of 9 hours.
TAS at 5900 ft at a "steady cruise power" is 126 knots.
Climb rate is about 950 ft / minute at full power.
Average fuel burn so far is around 15 litres / hour (4 US gallons / hr).

Dave
 
RV9 / WAM 120

I also have an RV9 (tail dragger) with a Wilksch diesel. I first flew it in November '08, and have had excellent results so far. I am experiencing the same kind of performance numbers as Dave describes, and I have yet to install my gear leg fairings and wheel pants.

The Wilksch factory people have been very supportive and cooperative as I've tried to perfect my cooling system to be prepared for the Nevada heat I have to deal with. I've got it working well now, with plenty of margin for hot summer days.

I installed the standard resistive fuel sending units - I was not aware that there could be a potential problem. I have standard vents as well. I have logged 24 hours so far with no problems. I have done diesel conversions in several vehicles over the years, and have never had a problem. The Chevy Duramax trucks use the same type sending units. If anyone has any advice for me, I'd sure appreciate hearing it.

I have not yet put Jet A in the tanks. I've been flying on red diesel, which is costing me $1.62 / gal right now. Pretty cheap flying.

This weekend I flew it to the Alternative Engine Fly-in at Jean, NV. It sure generated a lot of interest. It took awhile for most folks to figure out it was an upside-down 3 cyl, turbo-intercooled diesel!
Kurt
 
Thanks for report Kurt

I was literally bombarded by my Russian buddies with questions about the motor after Dave's first flight. Please post some pictures if possible.

Waiting for more reports on performance...

Oh... and welcome to VAF!
 
Thank you gentlemen. Everything available from VAF and the Web on the motor is already memorized.
 
I'd be happy to post some pictures of my installation, but I can't figure out how. I can build a diesel airplane, but I can't post pictures! I'm sure my kids could do it! I'll keep working on it.
Kurt
 
Deleted posts, why?

I am posting this on here again, because I am not only totally annoyed by the ignorance of the Wilksch company, but now also because my post (and some others), regarding this issue, has been removed from this thread, by some moderator who, apparently, does not like to hear the truth! I am wondering how long this post will stay on here, this time!
Since somebody asked it before: No!....., Wilksch is not a company that is supportive and customer friendly!

I met Marc Wilksch and some of his associates , 4 years ago, at the bar of the hotel that I stayed in, when I was visiting Aero Friedrichshafen 2005. He convinced me to build an RV 9 and install his new diesel engine, that he was selling to the experimental market. The WAM120 was already finished and the WAM160 was coming very soon. Mind you, this was the inventor/engineer/manager/director himself!

Before ordering my kit, I met Marc Wilksch again in the UK, demonstrating his WAM120 equiped plane to me at the PFA ralley (static, not flying!). After a while, I ordered the RV9 kit and started building. While building, I tried to keep in touch with WAM and found out that Marc Wilksch had left the company. I spoke to several other people in the company, but they never came back to me and I was not able to get any firm commitment or place an order for my engine, at all!

I actually flew to the UK, again, to see the owner of a plane, that was equipped with a WAM120. Unfortunately the plane had problems with the fuel supply and there was a problem with the pre-combustion chambers, that had to be replaced (apparently on all engines). The plane had only flown a dozen hours or so and could not be flown during my visit.

After trying to get a confirmation for the delivery of an engine from WAM for another 1/2 year or so, without any response from Wilksch Airmotive, I gave up and started looking for another engine.

For me this was a total waste of time and money. I even made changes to my plane, to accommodate the diesel engine, all for nothing! It would be unfair to other builders, who are interested in this engine, and still think they can just go out and buy it, to withold this information.

Kind regards, Tonny.
 
New engines delivery

Tonny,
Sorry to hear of your troubles. Sad as your story is, it is all too common. Not makling excuses for WAM but no one that hasn't done custom engineering has a clue of how tough it is to bring a complete product to market. Everyone harps on DeltaHawk taking so long to get engines to market, but they are trying to get the job done right before release. A manufacturer can produce a one-off prototype for a lot of money and show it to people, but going into production is another matter. All of the little tweaks and changes need to be incorporated and updated into a production item. Just getting the casting for the engine block, or cylinder heads can be another battle by itself. Most engine designs don't lend themselves to being built cheaply by machining all the parts on a CNC machine. I believe Wilisch was also getting government money durring the development. Making the jump from prototype to production has left a trail of deceased companies behind. Much harder than it seems!
Bill Jepson
 
RV9 / WAM 120

Tonny,
I'm also sorry to hear of your troubles. When I ordered my WAM 120 about 3 years ago, I also did not get very good response from the factory. But I did get an engine, an engine mount, and all of the accessories that I needed - at about the time I needed them. During my installation, I had questions, and the answers came slowly.

But I must say that over the past year, things have changed - the folks at WAM have been easy to contact, quick to answer emails. When I was ready to fly, they sent someone all the way to Las Vegas, NV to install the new precombustion chambers, adjust the power and propellor settings, and to help with the first flight. Kerry Ashcroft was very knowlegable and helpful - and a very enjoyable person to be around.

There have been two service bulletins sent to me over the past two years, very complete, with all required parts, step-by-step illustrated instructions, everything I needed. They were minor items, but very professionally done.

As I have worked to perfect my intercooler system, they've been behind me and helping me all the way. As far as I'm concerned, I could not ask for a better experience, especially from a factory so far away from me.

I knew in the beginning what I was getting into, and things have seemed hopeless at times, but WAM has come through for me. I've been in regular contact with four of the other RV9 / WAM builders over the last three years, and although there have been some irritations, generally things have gone well. When you get into technology this new, you have to expect some setbacks. But the results have been well worth it for me so far. I have enjoyed the challenge!
Kurt
 
Dave - thanks for posting these pics for Kurt. I intend no insult or injury, but would express a preference for the cooling/cowling design Kurt has used. Like most aircraft engines, getting the cooling right can be the hardest job, so I'm sure Kurt pulled his hair out before arriving at this working design. Likewise, Dave, you chose to use a known commodity for your cooling setup, with I'm sure a faster total build time and probably a lot fewer headaches. Alternative engines seem to require the builder to make the choice between innovation and accepting the design of another.

In the end, the results obtained by you and Kurt are very encouraging. At the moment I can't afford the weight of a diesel in my aircraft, but am looking forward to the day when I have an aircraft that will burn "heavy" fuel. Thanks again for the very informative and encouraging post!
 
She ain't heavy..

. At the moment I can't afford the weight of a diesel in my aircraft, but am looking forward to the day when I have an aircraft that will burn "heavy" fuel. Thanks again for the very informative and encouraging post!

Weight is 473 kg, 1043 lbs. CG 76.9 Inches AOD. We have a Flightline Interior with leather & confor foam seats, no spare space in the panel (though we have the glove-box fitted), a massive battery (Odessey PC925) and an MTV-21 propellor. I think that's not heavy for a -9A. The other installations I've seen numbers for have come out with similar weights.

I think if I lived in the desert I'd have gone with an installation like Kurt's, but in these green & pleasant lands it looks like I have cooling to spare for all but the hottest days, and on the hottest days I can accept throttling back a little 2 minutes after take-off to keep the coolant temp in limits.

What's your W&B Kurt?

Dave
 
she aint heavy...

My empty weight, including oil, coolant, basic interior and basic panel, no fuel or wheel pants is 974 lb. I have since added about 4 lbs to my intercooler setup. Empty CG is 76.32 AOD.

I imagine that with paint and wheel pants it well weigh in somewhere around 990? I'm planning on polishing a good portion of the plane.

Kurt
 
By the way, gents, I should add that both of your airplanes have, to my eye, much more appealing lines than a typical Lycoming installation. The inverted in-line engine allows for cowlings that harken back to the sweetly flowing lines of the Tiger Moth and Chipmunk. Mmmm, very nice lines indeed!

My comment about weight wasn't meant to imply the WAM is heavy - sorry if I may have implied that - it was more to state that my particular aircraft needs something lighter. You've both done an admirable job in keeping the empty weight down. Those airplanes will no doubt be a delight to fly!
 
How's the drag?

Wow, brilliant installation Kurt. Nice looking cowling. Your plenum is very similar to what I imagined a low drag installation might look like. Do you have a sense whether the aerodynamic drag is competitive with a typical Lycoming installation?

I like the WAM concept. But why bother if increased drag erases the engine's efficiency gains?
 
cooling drag not too bad

I've been putting a few hours on lately, trying to fly off Phase I (I've got 35.3 as of today!). I've been checking my numbers against the numbers on Van's website for the O-235 118 hp. I'm getting 150-155 mph TAS at 7500 ft, but without wheel pants or gear leg fairings. So once I get them installed, I'll be very close to Van's published numbers. Burning 4-4.5 gph red diesel. I'm pretty happy so far!

I've also been flying on some pretty hot days. At 34C (94F)I'm able to take off and climb with full power at 900 fpm 90 mph to 5500' (my airport's at 2200') and never come close to red-lining coolant, oil, or intercooler temps.
Kurt
 
I spot VW parts.... :)

Sounds like Cessna-like performance... hope to hear more when the fairings get put on.
 
I've only done numbers for 55% power. We got 126 knots at 6000 ft; that's 145 mph compared to 150 mph at 8000ft for Vans numbers, so we're pretty close to that one and will pick up a couple more knots when we go to 8000ft.

We designed our installation for simplicity rather than minimum drag, and its still pretty good.

We're grounded at the moment, we've finished our intital test period and are waiting for our full permit to fly to be issued.



Dave
 
Impressive

I've been putting a few hours on lately, trying to fly off Phase I (I've got 35.3 as of today!). I've been checking my numbers against the numbers on Van's website for the O-235 118 hp. I'm getting 150-155 mph TAS at 7500 ft, but without wheel pants or gear leg fairings. So once I get them installed, I'll be very close to Van's published numbers. Burning 4-4.5 gph red diesel. I'm pretty happy so far!

I've also been flying on some pretty hot days. At 34C (94F)I'm able to take off and climb with full power at 900 fpm 90 mph to 5500' (my airport's at 2200') and never come close to red-lining coolant, oil, or intercooler temps.
Kurt

Would the 135HP numbers published by Van's be a better comparison for altitude airspeed performance? I would think the turbo helps maintain rted power at altitude (100HP max continuous) which is very close to 135HP at 75%. The O-235 is huffing along at only 88HP at altitude. The O-235 would be a better comparison for takeoff performance at sea level.

Still, 4.5 gph gives 8 hours range and at 155 mph that is 1,240 miles. Wow! I too would be happy with that. Something like 3-400 more miles on a tank of fuel compared to a gasoline burner.

On second thought, 4.5 gph is 31.5 lbs/hr and at .43 lb/hp hr (per Wilksh) yields only 73 hp. You would be burning 45 lbs/hr or 6.2 gph to get max continuous rated power (per Wilksh).

So 73 hp @ 7,500' without aerodynamic fairings to get 155 mph compares reasonalby to the O-235's 88 hp @ 8,000' to get 167 mph. It would seem based on fuel consumption that what is keeping you from getting 175 mph at 8,000' is that you're not running at max continuous power as opposed to excessive drag.
 
Would the 135HP numbers published by Van's be a better comparison for altitude airspeed performance? ...
No, I think the 108 HP O-235 numbers are closer.

My 135 HP RV-9 has a climb prop and I cruise it at 165 MPH True at 8500' at 64% power. Some day I'll get a cruise prop and when that happens I expect to get up closer to 180 MPH true based on what I'm seeing now.
 
I haven't got that scientific yet. The numbers I gave are at my normal cruise, which is 85/85. You're right, I can get more speed at 100/100, but not that much. I really don't intend to cruise at 100/100, so I haven't checked it out at altitude. I have heard from another RV9A/WAM owner that 100/80 gives a lot more speed, so I tried it for a few minutes and he was right. I contacted the factory to see what they thought, but they did not recommend it, as they had not tested that way.

This morning I was fueling my plane and emptied my supply tank. So I did a little math: 155 gallons of fuel used in 35 hours = 4.42 gph average with 42 T/O and landings. I might be off a gallon or two, but not much.

BTW, there are a few VW Parts, but not on the engine. The coolant expansion tank, low coolant sensor relay are sourced from VW.

So far, so good. This may not be for everyone, but as a diesel guy, I love it.
Kurt
 
BTW, there are a few VW Parts, but not on the engine. The coolant expansion tank, low coolant sensor relay are sourced from VW.

So far, so good. This may not be for everyone, but as a diesel guy, I love it.
Kurt

Yep, the coolant tank was what caught my eye. I like the installation so far.
 
What do 85/85, 100/100 and 100/80 mean?

They are manifold pressure (MAP) / RPM. Manifold pressure is absolute pressure, 50 is 1 atmosphere, 100 is 2 atmosphere. RPM is % max propeller RPM (2750 RPM).

The engine is cruised with MAP=RPM 85/85 90/90 or 95/95 are nice relaxed cruise powers.

85/85 is 62hp
90/90 is 67hp
95/95 is 70hp
100/100 is 75hp
120/100 is max continuous power 100hp
140/100 is full power - 120 hp (5 mins limit)

Dave
 
Interesting

Thank you. This is interesting and revealing. Prior I had assumed that the WAM turbo just 'normalized' or maintained sea level manifold pressure like most aircraft applications. It appears that in order to produce any power at all the manifold must be boosted beyond sea level. Duh. I should have realized this before (I'm not an engineer). This is a 2-stroke diesel and the rules are a little different. The intake mainfold must have higher pressure than ambient in order for the flow to be in the right direction. On the power stroke the exaust port must open slightly before the intake port to ensure the cylinder pressure is closer to ambient so that a fresh charge can enter the cylinder from the intake manifold for the next power stroke.

I can see why 85/85 is a preferred cruise. A propeller at 2,750 RPM would be a bit noisy for a long ride. I can also see why an overbored WAM has been discussed. Set to 62 hp for a comfy crusie seems to leave a fair amount of the RV-9's performance potential unused.

Is it correct to assume that a constant speed prop is necessary to finely control MAP/RPM numbers?

I like it. When can I start?
 
Fixed Vs Variable Pitch Prop

Wilksch are using a fixed pitch prop on their 100hp version, but the 120hp version needs a VP prop. At the high specific power the engine is producing then you need all the revs to keep away from the smoke point at high power.

With the new big-bore engine you'd probably be able to use a fixed-pitch prop with it rated at 120hp, but need a VP if you went much higher.

Dave
 
Good job!!!

Outstanding. Good job. I truly can appreciate the extra effort it took you get to where you are.
 
Back
Top