A different 172

White Bird

White Bird

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White Bird
Read the description on that page. It's got a FADEC driving a diesel engine.
 
According to the site, Useful load = 631 lbs. With full fuel that's what, 373 lbs of pax & baggage?
 
That is an amazingly equipped 172 that can only carry 2 people.... I notice there is no price...
 
If it wasn't for the low useful load that would be an awesome plane.

I would imagine flight schools would be interested in something like that though.
 
That useful load, must be a typo. The Redhawks have the same exact spec out, and Max Usable is 780lbs and utility 480lbs. which is just about 100lbs less than a standard 172 because of the heavier engine.

However, your fuel burn is half standard, you carry a little less fuel weight because of the JetA and you have max performance at climb, cruise and decent. So everything equals out.

Plus that one doesn't even have the new Hartzel composite prop. :nono: I'll take a Redhawk at $249k over that or anything else anyone is trying to make.
 
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Cykoguy said:
If it wasn't for the low useful load that would be an awesome plane.

I would imagine flight schools would be interested in something like that though.
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Agreed on both points. Would be an awesome plane for...me. Since that's how I normally fly, wouldn't be a problem.
 
pretty much useful to bore holes in the practice area. and with the price difference you can buy several years of avgas and buy a new lycomming. i really dont understand the diesel economies in place were avgas is everywhere.
 
Looks like you saw the 172 diesel with single lever control. Would like to get a flight in one ,as a comparison to the gas aircraft.
 
That is an airplane that I definitely would NEVER let anyone else put fuel in without being physically present at the time despite the numerous placards.
 
Silvaire said:
That is an airplane that I definitely would NEVER let anyone else put fuel in without being physically present at the time despite the numerous placards.
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Do the diesels not like Avgas at all? Are they not like turbines?
 
Silvaire said:
That is an airplane that I definitely would NEVER let anyone else put fuel in without being physically present at the time despite the numerous placards.
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Yep, keyed gas caps, and you have the only key on your keyring!
 
Pedals2Paddles said:
That is an amazingly equipped 172 that can only carry 2 people.... I notice there is no price...
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That

And only 135hp on a engine that might not be well supported in 10+ years...


Cool concept, but poor delevery.
 
Bad things happen when you put gasoline in a high compression diesel engine.
 
Pedals2Paddles said:
Bad things happen when you put gasoline in a high compression diesel engine.
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Like what?

It compression-ignites?

The issues in cars are related to the much higher viscosity of Diesel fuel. They run like total crap, but don't blow parts into the next county.
 
MAKG1 said:
Like what?

It compression-ignites?...
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Yea but not at the right time. Would you like to take off with your magneto cranked 30 degrees off of where it's supposed to be?
 
Silvaire said:
Yea but not at the right time. Would you like to take off with your magneto cranked 30 degrees off of where it's supposed to be?
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Well, no, but that ought to be really obvious.

We all do initial power checks, right? In a 172, full throttle, RPM=2300 or higher immediately (at least at sea level). If not, abort the takeoff.

With 30 deg advanced timing, I'd be surprised if the engine even passes the idle test during run-up.
 
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All I'm saying is it's a 172 so the chances of somebody unawares putting the wrong fuel in is very likely. The mixture ratio could be anything, it might not be noticed but could create trouble at a critical point and over an extended period could cause damage to a very expensive engine.

So if I owned one I'd want to make darn sure than no Avgas ever got put in there and the only way is to NEVER let anyone put fuel in the tanks without me being present.

That was my point
 
F01LA said:
I think it falls under the category of "If you have to ask.."
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If I was in a position of not having to ask, then I would not be looking at a 172 of any stripe.

I also failed to see any performance data. How fast does this thing fly compared to fuel usage. If I slow my 172 down and lean it out I can get higher range and lower noise too. So how much does the diesel buy me vs what it costs me in performance.

If I had the cost and performance numbers, there is a chance I would look into this further. But I suspect the cost would push me towards something bigger, faster and cheaper.
 
JOhnH said:
If I was in a position of not having to ask, then I would not be looking at a 172 of any stripe.

I also failed to see any performance data. How fast does this thing fly compared to fuel usage. If I slow my 172 down and lean it out I can get higher range and lower noise too. So how much does the diesel buy me vs what it costs me in performance.

If I had the cost and performance numbers, there is a chance I would look into this further. But I suspect the cost would push me towards something bigger, faster and cheaper.
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In view of the lack of performance data, what is wrong with this logic?

75% of a 135HP Diesel is about 101 HP.
101 HP is about 44% of an O360.
What kind of speed and range would I get at 44% power in my 172. I'm not even sure I could stay in the air at that setting.

Don't get me wrong. I'm not bad-mouthing or nitpicking the plane/engine. I'd love to consider it if I thought then numbers played out.
 
Is horsepower the right number to be looking at?
What about torque?
Typically, diesels have lots more torque than gas engines.

So maybe this is spinning a steeper pitched prop with lots more torque?
Like a lower final drive in a car, since the motor has the power to spin it without lugging. (Not sure how the airplane's gear drive affects this.)
 
:wink2:
G-Man said:
Is horsepower the right number to be looking at?
What about torque?
Typically, diesels have lots more torque than gas engines.

So maybe this is spinning a steeper pitched prop with lots more torque?
Like a lower final drive in a car, since the motor has the power to spin it without lugging. (Not sure how the airplane's gear drive affects this.)
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I thought about that bi also wondered if the diesel can be sFely run at greater than 75% power. I just haven't been able to find the answers about performance.
 
I don't think you can deduce anything from raw hp figures. I know I own a 7.3 liter Ford F350 diesel and it's only rated at something like 150 hp but as a truck it certainly performs as well or better than the equivalent gasoline version. In the case of aircraft I think you are looking at a number of factors such as the possible future difficulty of finding 100LL. There is also the simplicity of the diesel as there is no ignition system (no magnetos, spark plugs or wires) no carburetor or mixture control and actually no throttle.

So as an aircraft engine there are advantages and reasons to go with a diesel but it's not necessarily a slam dunk based on performance.
 
Silvaire said:
I don't think you can deduce anything from raw hp figures. I know I own a 7.3 liter Ford F350 diesel and it's only rated at something like 150 hp but as a truck it certainly performs as well or better than the equivalent gasoline version. In the case of aircraft I think you are looking at a number of factors such as the possible future difficulty of finding 100LL. There is also the simplicity of the diesel as there is no ignition system (no magnetos, spark plugs or wires) no carburetor or mixture control and actually no throttle.

So as an aircraft engine there are advantages and reasons to go with a diesel but it's not necessarily a slam dunk based on performance.
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I agree, but I would still need some sort of performance numbers before I would seriously consider one. Why is that information so hard to come by? We can speculate, extrapolate, theorize till the cows come home, but if they want to sell those things (to me any way), they need to publish some actual data.
 
I dont know too much about diesel aviation engines, but I know if you put gasoline into a diesel truck and run it for more than a few seconds you can do some serious internal damage. Compression ratio of a diesel is about double that of a gasoline engine, which means your fuel mixture is likely to ignite just about halfway through the compression stroke with the wrong fuel. That's serious bad news for a motor, if it would even keep running.

As for HP figures, I dont know why but diesel numbers never line up with Gasoline numbers. I see big diesel pusher motorhomes all the time that brag about 300hp, where 300hp isn't even impressive in a gasoline powered sportscar anymore. Big difference is the 300hp sports car will have around 300lb.ft of torque, whereas the 300hp motorhome may have closer to 1500lb.ft. I would be surprised if they would build a high end version of a 172 like this, with the added cost of the diesel engine if the performance was lower than a standard Lycoming.
 
StinkBug said:
... I would be surprised if they would build a high end version of a 172 like this, with the added cost of the diesel engine if the performance was lower than a standard Lycoming.
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I agree 100%. But again, this is just supposition and interpolation.

So why don't they publish the numbers?
 
Possibly because the way Diesel engines make power, and how they are rated makes them look really weak when you put the numbers side by side with the numbers of a gas motor with equal performance. They wanna advertise strengths, not give people something to nitpick. Just a guess.
 
Used to rent a Theilert 172 out of 5T6 on a regular basis.

I would always choose it over an Avgas 172.

Between the constant speed prop and the enhanced altitude performance of the turbo, the diesel out-climbed and out-ran the rest of the 172s in the fleet.

Here are the numbers from a pprune thread. Note, 4000' is about the HP break-even altitude, but climb rate matches at closer to 2000', which I would imagine is probably due to the CS prop and FADEC keeping the engine in its sweet spot.

Above 2000', it all favors the diesel, which never felt flat, even at 10-12,000'.

I'd be step climbing the 172 well below those altitudes on a hot day.

Oh, and 5T6 airport altitude is 4112'.

TAe125_power-alt_2.jpg
 
ElPaso Pilot said:
Used to rent a Theilert 172 out of 5T6 on a regular basis.
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Thanks, that's good information.

One thing it shows, which is what I expected, is that the diesel is able to use more of it's rated HP as altitude increases.

But while it beats an O320, it doesn't do as well against the O360.

And I would like to see other performance stats too, primarily cruise speed.

Even if I took the plunge my results would not be as financially beneficial because at my home airport, Jet A is $5.50 and Avgas is $4.95. So it would take a lot more flying than I do to have a pay-back in fuel savings. At least for the next few years, when Avgas may go up even more, or disappear.

I think I will still be looking for a good deal on a Mooney or a 182 or a Debonair or . . .
 
JOhnH said:
Thanks, that's good information.

One thing it shows, which is what I expected, is that the diesel is able to use more of it's rated HP as altitude increases.

But while it beats an O320, it doesn't do as well against the O360.

And I would like to see other performance stats too, primarily cruise speed.

Even if I took the plunge my results would not be as financially beneficial because at my home airport, Jet A is $5.50 and Avgas is $4.95. So it would take a lot more flying than I do to have a pay-back in fuel savings. At least for the next few years, when Avgas may go up even more, or disappear.

I think I will still be looking for a good deal on a Mooney or a 182 or a Debonair or . . .
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The Theilert was faster at altitude, but... "designed in" airframe drag is a bigger contributor to cruise speed than HP. You can add a lot of HP to a C172 (or C152) and have little improvement on airspeed.

The conversion cost will also take your breath away. I think I paid less for my decent M20J than the FBO did to convert that 172 to diesel.
 
ElPaso Pilot said:
The Theilert was faster at altitude, but... "designed in" airframe drag is a bigger contributor to cruise speed than HP. You can add a lot of HP to a C172 (or C152) and have little improvement on airspeed.

The conversion cost will also take your breath away. I think I paid less for my decent M20J than the FBO did to convert that 172 to diesel.
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That's pretty much what I thought.
My 172 picked up payload and climb with the 180 upgrade, but not speed. But there is still a lot I like about the diesel.

But it doesn't appear to be worth the $$$ yet, so I'm still looking for a good deal on a faster single.
 
JOhnH said:
That's pretty much what I thought.
My 172 picked up payload and climb with the 180 upgrade, but not speed. But there is still a lot I like about the diesel.

But it doesn't appear to be worth the $$$ yet, so I'm still looking for a good deal on a faster single.
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Well, that won't be in a 172.

What's your mission for 85% of your flights? (# pax, range, desired cruise speed, budget, typical weather and terrain)

Every plane is an engineering and performance compromise for a specific set of tasks. You just need to match all of those up with something in your budget range.
 
ElPaso Pilot said:
Well, that won't be in a 172.

What's your mission for 85% of your flights? (# pax, range, desired cruise speed, budget, typical weather and terrain)

Every plane is an engineering and performance compromise for a specific set of tasks. You just need to match all of those up with something in your budget range.
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95% of our flights are just two people (~350#s), but we do occasionally take friends and family up. 4 pax would be all we need.

We do make quite a few "hamburger" runs of about 150 miles, but we also like to take 1-2Week vacations and see places we have never seen before. Plus, we fly to conferences for work which may be anywhere in the Country. I suppose we make about 5 or 6 trips a year greater than 1,000 miles.

We also plan to retire in the near future and expect to make even more cross-countries for the first few years.

We'd like to be able to go Coast-to-Coast in two days. We'd like each leg to be at least 500 miles and take less than 3 or 4 hours.

And we want a reliable airplane that doesn't need a lot of work and doesn't keep breaking down. Our 172 pretty much fits this criteria, and it can easily carry 4 adults with (some) luggage, but it is just too slow for everything else we want to do.
 
StinkBug said:
I dont know too much about diesel aviation engines, but I know if you put gasoline into a diesel truck and run it for more than a few seconds you can do some serious internal damage. Compression ratio of a diesel is about double that of a gasoline engine, which means your fuel mixture is likely to ignite just about halfway through the compression stroke with the wrong fuel. That's serious bad news for a motor, if it would even keep running.
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It can't ignite half way up the compression stroke because the fuel isn't injected until you get to the top of the stroke.

But, gasoline will not properly lubricate the high pressure injection pump - that's what will get expensive.
 
JOhnH said:
95% of our flights are just two people (~350#s), but we do occasionally take friends and family up. 4 pax would be all we need.

We do make quite a few "hamburger" runs of about 150 miles, but we also like to take 1-2Week vacations and see places we have never seen before. Plus, we fly to conferences for work which may be anywhere in the Country. I suppose we make about 5 or 6 trips a year greater than 1,000 miles.

We also plan to retire in the near future and expect to make even more cross-countries for the first few years.

We'd like to be able to go Coast-to-Coast in two days. We'd like each leg to be at least 500 miles and take less than 3 or 4 hours.

And we want a reliable airplane that doesn't need a lot of work and doesn't keep breaking down. Our 172 pretty much fits this criteria, and it can easily carry 4 adults with (some) luggage, but it is just too slow for everything else we want to do.
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You seem to have a better handle on your needs than most!

With those kinds of trips and time requirements, a 172 is definitely not your long-term plane.

I had very similar needs, with a 1-day requirement from El Paso to the NY area.

The one thing you didn't put down was your budget. I ended up zeroing in on an early M20J, and the older Debs and Bo's. Was interested in the single Grummans as well, but they didn't have the high altitude performance or range I was looking for, and 182s were too slow for the fuel burn.

Flew a Deb and the Mooney repeatedly, and ended up with the Mooney. Could have gone either way, but I liked the additional efficiency of the J, and the cramped entry didn't bother me or the family.

Love the long legs, too. ELP to Chicago is over 1000nm, and I have done that non-stop, when the winds are right, on 64 gal tanks. With that kind of range, I can take on some really large diversions (think multiple states away) around weather and still make my destination. That wing also has a service ceiling of 18,800' at gross, and in the 20's light.

Overall, very happy with the purchase, and would likely have been so with the Deb as well.

You may want to make up a spreadsheet with the GPH, Cruise speed, and ranges of the short list you are looking at. You can quickly generate a fuel cost/mile (a Bo or J is much more economical over those distances than a 172).

See how long it will take you to do your trips with fuel turnarounds, and what those flights will cost you in the planes you are looking at. It gave me a much better idea of what I needed to purchase, and for me that required sucking up the gear.
 
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