Diesel powered 337

[Rick Gardner]

I was told today that someone has converted the front engine of a 337 to diesel somewhere in the northeast USA and is flying it under a restricted category. Has anyone heard of this who could elaborate and does anyone know of any plans to retrofit diesels on a 337?

Rick Gardner
www.caribbeanskytours.com

[EB338]

I too would be very interested to hear more on this subject. I have been doing some research on the topic and would assume they used the Centurion 4.0 by Thielert in Germany. That is the 350hp V8 water cooled engine with the gear reduction unit that runs on Jet A. I know it is not safe to assume anything but this is the only diesel I could find that was close to big enough. They already have kits to convert 206's, 340's, 414's, and 421's, as well as Beech Duke B60's, so the front end of a 337 should not be much of a stretch.

They claim more static thrust for the HP than conventional because of the higher torque and to be burning about 12gph (per engine) which could get 350hp 337s running for less than $100/hour in fuel up in the 300mph neighborhood. They are however almost 200lb heavier each than the TSIO550's, not to mention 4" wider, 6" taller, and 3" shorter but I don't know if any of those numbers include the gear reduction unit, and I am not entirely sure how their water cooling system fits in the cowl or how much more weight that adds to the package. I also found it interesting they offer no TBO as they are supposed to be replaced not rebuilt every 2400hours. They also take mixture and prop control and hand them over to the computer which like most new technology sounds great when it works.

Anyone know anything more?

[Skymaster337B]

I would rather have a small turbine running then a diesel.

[AussieO2]

Delta Hawk Diesel Engines, http://www.deltahawkengines.com/archives.shtml
N1700M is the 337E.

[hharney]

Delta Hawk has been testing for several years now. There should be more info on the board about this. Also, at the SOAPA meeting in Kalamazoo 2008 there was a presentation about this work that DH is doing. It pays to attend.

[Skymaster337B]

From what I can see on their web site it looks like a Diesel engine will be more expensive than a regular engine. But will the overhaul time be about the same?

[CO_Skymaster]

Does anyone know, when Thule-River talked about installing SMA diesels in a Skymasters, did they have to perform major modifications to the cowling like SMA had to do with the 182? Is there enough cooling in the Skymaster to dissipate the heat?

Karl

[WebMaster]

The front engine on a skymaster was a test bed for Continental. You may have read that Continental was sold to the Chinese. One of thing that was the impetus was additional funding for their diesel engine development.

Thule River/Super Skyrockets, looked at the SMA Diesel for the Skymaster. It was intended to increase their market for modifications. I had the good fortune to be at Osh when Marianne ( Mary Ann ?? ) the owner of Super Skyrockets spoke to the Skymaster group. It was a meeting put together by Kevin McKenzie. In any event, the SMA engine conversion was intended for the normally aspirated Skymasters. That's because the certified ceiling for the engine was 10.5K. The project never got off the ground for several reasons. First, SMA was slow to produce and respond. The Skymaster conversion was not tops on their list. Second, SMA never produced an engine designed for pusher engine installations. I spoke at length with the folks at Super Skyrocket, about the time I needed a new rear engine, and that was their response. Interestingly enough, Continental does not differentiate between tractor engine and pusher engines. Third, Super Skyrockets was looking for additional markets for their business (the Riley Conversions were not selling real well), additional conversions they could do. They did a considerable amount of work with a variety of "New Engine Technology" companies, and I think they simply got worn out trying to come up with something that was certified, or certifiable. They have since closed their doors, and it's not likely that anyone else will take up the mantle to install SMA engines in a Skymaster.

Delta Hawk, on their website, had a date for certification. That date has come and gone. Super Skyrockets looked at the Delta Hawk engine, and in fact commissioned a study for engine mounts. There was a really cool solid model of the front engine mount for the Delta Hawk engine, on the Super Skyrocket site, for a while. It had the NASTRAN load analysis associated with it. Really cool looking.

[CO_Skymaster]

Thanks for the information Larry.

There were a couple issues I didn't like about the SMA diesels on the C182. 1. The extensive cowl modifications 2. I saw a video where they were demonstrating it in flight and they couldn't pull power all the way to idle incase of a flame out. Didn't like the sound of that, what if I need to go around or make a missed approach, 3. I like the idea of FADEC, but still don't like the idea of battery back up. What if the entire electrical system fails (I've had it happen at night) and your over water. The magneto system would allow you to continue to fly until you exhaust your fuel.

I was hoping that deltahawk would have the certified engines going by now, but I'm no longer holding my breath about it. I don't know how the sale of TCM to Technify will affect us in the long term, but I'm not feeling too doomed and gloomed about it either.

Karl

[WebMaster]

I don't know where they are getting the engines, but apparently TFHAWK is serious about a diesel Skymaster. I say I don't know, because Delta Hawk Engines is still in the testing phase. It could be that TF is working with them. In any event, I have learned that they are going to produce, and soon, what they call the "Golden Hawk" conversion. Pricing is expected to be about $340K, including new props and all mods. Some of the mods make a lot of sense. They say they will have engine block heaters and fuel heat. Heating the fuel is a good thing, because Jet fuel tends to gel, and attract moisture. Those jets who have fuel heaters don't need Prist added to the fuel. Since Prist is expensive, the fuel heaters are a good thing. They also say they are going to have dual electrical systems, another good thing. If you don't have the Gear Door STC, they want to to put it on. I have mixed feelings about that, but a lot of people have them. I remember Super Skyrockets saying they did not approve, because the wheels could collect ice. I know that when we cleaned Jerry's plane, his wheels tended to collect OIL. New engines would solve that issue. They also talk about electrical heated wing de-ice. I have seen this, and I have seen this removed. I think it would be up to you.

They will also put on the Horton STOL kit, and spoilers. Both good things to have. I have flown Herb's with the Horton, and it really helps on take off and landing. Jerry has spoilers, and those are great for getting down. There will be cowling mods, of course, and an MVP engine analyzer.

The price seems steep, but I don't think it is. When I flew Owen's SkyMonster, he was talking $350K for that mod, and that didn't include all the things that TFHAWK is talking about.

Changing engines is a big undertaking, because not only do you have the cost of the engines, you also need a newly designed engine mount, and new cowlings.

Being able to run Jet A should appeal to a lot of folks, especially when you consider that in some parts of the world, 100LL is virtually unattainable. When Paul and Mary flew up the Amazon, then needed to buy 100LL in 55 gallon drums, and have them delivered to their planned fuel stop. If they were burning Jet A, it would have been readily available.

When I get more information, I'll pass it along.

[WebMaster]

I have learned that as part of the certification process for the Delta Hawk engine, they are flying the engine in their Skymaster.

They also anticipate having certification this year.

[Morne]

Originally Posted by larry bowdish

I don't know where they are getting the engines, but apparently TFHAWK is serious about a diesel Skymaster. I say I don't know, because Delta Hawk Engines is still in the testing phase. It could be that TF is working with them.

According to their website:

Engines: Delta Hawk Diesel (2 each)

Some of their modifications are not applicable to civilian use (like armoring the crew seats). Not to mention the tip tanks that some folks just don't want.

Still, great to see SOMEBODY will be doing it!

I kind of wonder what they'd charge just to replace the engines/mounts/props?

[hharney]

Here is what I have learned:

You can expect the Golden Hawk conversion to be in the range of $340,000, based on using an existing customer-owned Skymaster that has no major defects and is moderately low time (i.e., like 2,500 to 3,500 TTAF) since zero-timing it is an option to add and above the base price. That includes a wide range of modifications, so it isn't just the engines that you get.

(Of note, this is not far from the Riley Rocket II pricing which they say "starts at $250,000" but some say in reality is more like $300,000 once you add in the equivalent modifications package that the Golden Hawk includes as standard.)

The standard Golden Hawk modifications package includes the following in the base price: new Hartzell propellers that have been custom-engineered and designed for the aircraft and engine; electrical strip tape anti-icing on wing leading edges and props; the gear door STC; dual electrical systems; an updated electrically actuated hydraulic system; fuel heat and engine block heat (for cold weather and high altitudes); modified cowlings, wrap-around front windshield without the central support; Horton STOL; an MVP-50P avionics system that is customized for the aircraft and engines; plus wing spoilers to allow the plane to descend more rapidly, and more.

All Golden Hawk aircraft will undergo an extensive 101-point inspection program, including the wing spar inspection that has been a widely discussed issue in the forum -- so this is a good way to get the inspection done and a major transformational upgrade at the same time.

Performance is essentially the same or better than the military version, which gives (based on the TFHawk.com website): more than 12 hours endurance on just 166 gallons of either Jet A, Russian TS-1 or diesel truck fuel from a regular truck stop, or any mixture thereof with no changes to engine settings; normal operating altitudes of up to 25,000 feet; no loss of power/manifold pressure up to FL185; and climb rates that are out of this world.

The plane can fly non-stop from Kitty Hawk to San Diego.

The company will offer the conversion in both non-pressurized and pressurized versions, though they state that the PRESSURIZED version may be preferred because of the typical high altitude operating profiles. Of note, this means that for the first time in Skymaster history, the heavier pressurized version of the plane (the P337) is superior! With the diesel conversion, there is sufficient power in the engines so that the extra weight of the P isn't a problem. Thus the Golden Hawk converts the old dog of a pressurized Skymaster into a little high altitude sportscar, giving the passengers extra comfort without having to wear masks or tube-based O2 in the plane. This will inject some life back into the Skymaster market, no doubt.


They are looking for some qualifying aircraft to convert..........don't forget the checkbook.

[ngb1066]

I have been interested for some time in the possibilty of installing diesel engines in a 337. For a time it appeared that the SMA four stroke 230-235HP engine was the only candidate and it appears to have been successful in the Cessna 182. The "improved" version of the SMA engine has just received EASA certification and this amongst other things raises the service ceiling, which was a problem with the original engine. There are apparently plans for SMA to bring out a 280HP model in due course. Tule River raised the suggestion of developing an STC for fitting SMA engines to the 337 a while back, but I do not believe they have taken the idea any further.

Thielert/Centurion have put on hold their plans for their 300+HP version of their engine and in any event the experience of users in the UK of the Thielert product has not been good.

The Deltahawk engine as a two stroke has always looked interesting, offering a better power to weight ratio than the competition. It can also burn motor diesel, unlike the SMA engine which is limited to Jet A or Jet A1. I have looked at the TF Hawk website setting out their plans for the 337 Goldenhawk with Deltahawk engines, but it is not clear how far they have got with that project. My main reservation about this is that the four cylinder Deltahawk engine will when certified, probably later this year, have a maximum power output of 200HP. I wonder if this is really sufficient to power a 337, particularly the heavier pressurised models. I would be interested to hear views on that. Deltahawk plan in due course to bring out 6 and 8 cylinder versions of their engine, offering power up to 400HP, but that is likely to be some time away.

[Morne]

Originally Posted by ngb1066

My main reservation about this is that the four cylinder Deltahawk engine will when certified, probably later this year, have a maximum power output of 200HP. I wonder if this is really sufficient to power a 337, particularly the heavier pressurised models. I would be interested to hear views on that.

Horsepower is not everything.

Check out the diesels on the Diamond Twin Star DA42 (yes, they are Thielerts, but follow along for a moment). They are 135HP each, not even the original Piper Apache had engines that wimpy!

But talk about fuel economy - that puppy cruises on roughly 10gph (5 per side) of Jet A and does it quickly. While the 337 retrofits will never be as aerodynamic or as light as the DA42s they still could be reasonably fast and fairly fuel efficient.