Aero Diesels
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Aero Diesels
Folks,
This may have been covered before but as a newbie to the forum please bear with me.
I've been thinking about moving to a diesel powered Warrior or 172 (cheap fuel, blah, blah) but I did hear a rumour that there is a weight penalty that reduces payload and makes the aircraft effectively a two seater. Anyone have any thoughts?
This may have been covered before but as a newbie to the forum please bear with me.
I've been thinking about moving to a diesel powered Warrior or 172 (cheap fuel, blah, blah) but I did hear a rumour that there is a weight penalty that reduces payload and makes the aircraft effectively a two seater. Anyone have any thoughts?
That may be true if you fill the tanks, but if you fuel according to your flight plan, you'll probably find they actually have an increased payload, due to the reduction in fuel burn.
I think, for a PA28/172 you have a choice of two STC'd diesel engines. SMA and Thielert. I'm sure their websites will give you some info on what the ultimate effect is.
A
I think, for a PA28/172 you have a choice of two STC'd diesel engines. SMA and Thielert. I'm sure their websites will give you some info on what the ultimate effect is.
A
Last edited by Andy_RR; 18th Jul 2006 at 11:03.
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Hi,
I have just joined a group owning a Diesel PA-28. I believe there are only 9 in the whole of Europe! You are correct about the weight thing. Just the other day (OAT of about 30 deg C), we performed a take off with less than 1.5 hours fuel on board. Speed built up nicely, and we were airborne by about 1200ft. But with two on board we were struggling to climb. I've never been so low on climb out from this airfield. I dread to think what would've happened if we had half full fuel tanks! I've got around 10 hours in it now and can say without a doubt that the weight penalty is certainly much greater than is mentioned by the manufacturers. Add a hot and humid day and it all gets very close. However economy is very good. Power back to 55% and you can really get to places.
I have just joined a group owning a Diesel PA-28. I believe there are only 9 in the whole of Europe! You are correct about the weight thing. Just the other day (OAT of about 30 deg C), we performed a take off with less than 1.5 hours fuel on board. Speed built up nicely, and we were airborne by about 1200ft. But with two on board we were struggling to climb. I've never been so low on climb out from this airfield. I dread to think what would've happened if we had half full fuel tanks! I've got around 10 hours in it now and can say without a doubt that the weight penalty is certainly much greater than is mentioned by the manufacturers. Add a hot and humid day and it all gets very close. However economy is very good. Power back to 55% and you can really get to places.
Wannabee 24 - surely thats a power issue rather than weight with only 1.5 hrs fuel on board? What did your W&B check tell you?
The diesel engine is presumably heavier than the original, but by how much I have no idea. Jet is around 7% heavier than Avgas, but as Andy RR says, less fuel will be required.
Rateone - Ask to see the POH for the a/c - it must have a new W&B schedule after being re-engined.
The diesel engine is presumably heavier than the original, but by how much I have no idea. Jet is around 7% heavier than Avgas, but as Andy RR says, less fuel will be required.
Rateone - Ask to see the POH for the a/c - it must have a new W&B schedule after being re-engined.
) ?
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Diesels
I will ask for the new W&B schedule. I was testing the water for other people's experience before getting a salesman all hot to trot.
I must admit, I hadn't considered the additional weight penalty of the fuel itself - good point. It seems from the responses that there may also be a power issue when compared with the equivalent Lycoming and the manufacturers are always going to put the best gloss on it. Struggling to climb with two up and with only 1.5 hours of fuel on board (I assume no bags) is not great, even if the temperature is 30 degC.
Thanks folks
I must admit, I hadn't considered the additional weight penalty of the fuel itself - good point. It seems from the responses that there may also be a power issue when compared with the equivalent Lycoming and the manufacturers are always going to put the best gloss on it. Struggling to climb with two up and with only 1.5 hours of fuel on board (I assume no bags) is not great, even if the temperature is 30 degC.
Thanks folks
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Originally Posted by Wannabe24
Hi,
I have just joined a group owning a Diesel PA-28. I believe there are only 9 in the whole of Europe! You are correct about the weight thing. Just the other day (OAT of about 30 deg C), we performed a take off with less than 1.5 hours fuel on board. Speed built up nicely, and we were airborne by about 1200ft. But with two on board we were struggling to climb. I've never been so low on climb out from this airfield. I dread to think what would've happened if we had half full fuel tanks! I've got around 10 hours in it now and can say without a doubt that the weight penalty is certainly much greater than is mentioned by the manufacturers. Add a hot and humid day and it all gets very close. However economy is very good. Power back to 55% and you can really get to places.
I have just joined a group owning a Diesel PA-28. I believe there are only 9 in the whole of Europe! You are correct about the weight thing. Just the other day (OAT of about 30 deg C), we performed a take off with less than 1.5 hours fuel on board. Speed built up nicely, and we were airborne by about 1200ft. But with two on board we were struggling to climb. I've never been so low on climb out from this airfield. I dread to think what would've happened if we had half full fuel tanks! I've got around 10 hours in it now and can say without a doubt that the weight penalty is certainly much greater than is mentioned by the manufacturers. Add a hot and humid day and it all gets very close. However economy is very good. Power back to 55% and you can really get to places.
? High temps can degrade performance a lot more than many people realise....
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It used to state on the Centurion website that the take-off and climb performance to 2000ft was worse with the Centurion engine fitted - despite their being a constant speed prop up front. Tells you something as the real performance gain with a CS prop is with the take-off and climb.
This was confirmed by the CSE salesman when he came visiting with the converted PA28 and also stated that the cruise was down 5kts and that it really turned the 161 Warrior to a 2+1ish seater with any reasonable endurance fuel-wise on board. IIRC the Centurion conversion weighs about 120lb more than the original Lycoming version.
Cheap fuel (if you can buy it at the airfield you stop at) and you can't have it maintained at many places - not good if you have a problem or at times of scheduled servicing.
This was confirmed by the CSE salesman when he came visiting with the converted PA28 and also stated that the cruise was down 5kts and that it really turned the 161 Warrior to a 2+1ish seater with any reasonable endurance fuel-wise on board. IIRC the Centurion conversion weighs about 120lb more than the original Lycoming version.
Cheap fuel (if you can buy it at the airfield you stop at) and you can't have it maintained at many places - not good if you have a problem or at times of scheduled servicing.
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Roughly speaking, the climb rate of any plane is just the engine HP and the weight. Aerodynamics barely comes into it, at the low speeds involved.
Most diesels are of lower HP than the engines they replace, and given that a part of the engine HP is used to overcome the parasitic drag at say Vx, even a small loss of HP is going to have a big negative effect on climb rate.
If you have a turbo diesel (which most are) then you start to gain at about 8000-10000ft, but while there are patches in the UK where one can do that, to routinely cruise there in most of Europe one needs a full IR, and very few private pilots (outside the N-reg community) have one of those....
Most diesels are of lower HP than the engines they replace, and given that a part of the engine HP is used to overcome the parasitic drag at say Vx, even a small loss of HP is going to have a big negative effect on climb rate.
If you have a turbo diesel (which most are) then you start to gain at about 8000-10000ft, but while there are patches in the UK where one can do that, to routinely cruise there in most of Europe one needs a full IR, and very few private pilots (outside the N-reg community) have one of those....
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SMA Jet A1
For any body interested in the SMA powered C182Q go to www.teamvencap.com.
The aircraft is undertaking a mamouth trip to somewhat warmer climates. includes pictures and logs and a diary of the adventures. Some legs of thrip 1,000nm plus.
The aircraft is undertaking a mamouth trip to somewhat warmer climates. includes pictures and logs and a diary of the adventures. Some legs of thrip 1,000nm plus.
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Why put a modern engine into an airframe which is based on a 1940’s design? If you go for a PFA two seater instead of a PA28 two seater you will save a fortune and also benefit from 60 years of technical advancement!
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That's very true; however these engines all seem to be hugely expensive, more so than any petrol engine of similar power, so too expensive for the Permit market.
I also think the diesel manufacturers were hoping for a lot of retrofit business (new certified plane sales in Europe are tiny); this is never justified unless the utilisation is very much higher than the average for the private owner, so they were hoping for a decent flying school take-up. That's not a bad market to aim for because the flights are usually very short (1 hour usually) so one can de-fuel to handle the W&B issues. Whereas a private owner with a decent plane will really want the max range, and is not going to be happy to have his 4-seater (effectively a 3-seater with luggage) transformed into another 4-seater which is effectively a 2-seater with luggage.
I also think the diesel manufacturers were hoping for a lot of retrofit business (new certified plane sales in Europe are tiny); this is never justified unless the utilisation is very much higher than the average for the private owner, so they were hoping for a decent flying school take-up. That's not a bad market to aim for because the flights are usually very short (1 hour usually) so one can de-fuel to handle the W&B issues. Whereas a private owner with a decent plane will really want the max range, and is not going to be happy to have his 4-seater (effectively a 3-seater with luggage) transformed into another 4-seater which is effectively a 2-seater with luggage.
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Originally Posted by Rod1
Why put a modern engine into an airframe which is based on a 1940’s design? If you go for a PFA two seater instead of a PA28 two seater you will save a fortune and also benefit from 60 years of technical advancement!
Rod1
Rod1
The PA28 Theilert with full fuel, true enough it will only carry two people on board. Which is ideal for the training role which most PA28's are used for. You can fly all day without re-fueling. The economics make sence too. Also bear in mind that the Thielert only uses 5.5GPH in the cruise, you don't have to carry as much fuel to get to your destination enabling the aircarft to carry that 3rd person. Plus the fuel is cheap.!
How many PA28 140's and 161's can you honestly fill full with fuel and 3 people on board legaly.?
There are lot's of benifits for the Theilert conversion and the retro-fit's are proving popular especialy with training schools and working aircraft.
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retro-fit's are proving popular especialy with training schools and working aircraft.
Why are Cabair trying to dump their DA40's? They have had so many problems.
These engines have the ability to be a huge step forward, but they aren't there yet. We have looked very closely at getting a DA40, but the reliability puts me off every time.
With regards to the power produced by the Thielert. I flew a DA40 TDI last year and was very surprised by the sluggish nature on the T/O roll. It was fine in the air, but that was in a modern airframe. I shudder to think of the performance in a retro-fit.....
If the manufacturers came up with a 150-200hp version, then they would do some business, but 135hp is just not enough and the SMA engines seem to be too large for your average spamcan.
Originally Posted by skyjock200
How many PA28 140's and 161's can you honestly fill full with fuel and 3 people on board legaly?
BEW - 1533.6 lb
Pilot + Pax - 458.6 lb (2 x lard-arses, I know)
Fuel - 300.5 lb (filled to tabs - i.e. not full)
Baggage - 11 lb (headsets, briefcase with nav kit and stuff etc)
Total - 2303.7 lb, which allows for a 22lb 3rd pax
I'd doubt it ever was a four seater, given that it was sold in the US of A!
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Why are Cabair trying to dump their DA40's? They have had so many problems
Didn't they put out a big press release a few weeks ago about buying a load more of them? I was curious about that, too.
The other thing about fittings in Permit planes is that they can't go IFR, and a large part of the attraction is the economy, which tends to imply long flights, which tends to imply... IFR. I know some Permit planes are very capable and some have great range but I don't think these top-end models make up a big market.
Andy_RR
You have just discovered the great secret of aviation
Next time you see a PA28 Warrior going to Le Touquet, 4 POB, ask yourself that same question 
And I bet they are not carrying a life raft either.
Mariner
The problem with small turbines is that their fuel flow per HP is about 1/3 more than piston. So, the fairly common turboprop conversions (Malibu e.g.) result in a much reduced range. You save money on the avgas tax but you then spend it on extra maintenance - a hot section inspection is about £5000. Maybe it will change one day but the efficiency issue is tough to crack. That's why jets and turboprops fly high; they need the "TAS gain" to make it worthwhile. They fly at levels at which oxygen would be impractical (high flow rate, poor oxygen endurance from a practical size bottle, discomfort from having to wear a full mask, heating problems) so they are nearly all pressurised hulls, which in turn really jacks up the purchase and operating/maintenance costs. Don't even think of the paperwork involved in fitting an extra GPS antenna on the roof of a pressurised airframe
Why are Cabair trying to dump their DA40's? They have had so many problems
Didn't they put out a big press release a few weeks ago about buying a load more of them? I was curious about that, too.
The other thing about fittings in Permit planes is that they can't go IFR, and a large part of the attraction is the economy, which tends to imply long flights, which tends to imply... IFR. I know some Permit planes are very capable and some have great range but I don't think these top-end models make up a big market.
Andy_RR
You have just discovered the great secret of aviation
Next time you see a PA28 Warrior going to Le Touquet, 4 POB, ask yourself that same question And I bet they are not carrying a life raft either.Mariner
The problem with small turbines is that their fuel flow per HP is about 1/3 more than piston. So, the fairly common turboprop conversions (Malibu e.g.) result in a much reduced range. You save money on the avgas tax but you then spend it on extra maintenance - a hot section inspection is about £5000. Maybe it will change one day but the efficiency issue is tough to crack. That's why jets and turboprops fly high; they need the "TAS gain" to make it worthwhile. They fly at levels at which oxygen would be impractical (high flow rate, poor oxygen endurance from a practical size bottle, discomfort from having to wear a full mask, heating problems) so they are nearly all pressurised hulls, which in turn really jacks up the purchase and operating/maintenance costs. Don't even think of the paperwork involved in fitting an extra GPS antenna on the roof of a pressurised airframe
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Originally Posted by Say again s l o w l y
Really? Most schools wouldn't touch a thielert engine with a long barge pole at the moment. They just aren't reliable enough. At the end of the day, a flying school needs reliability above all else and there is no way these engines are anywhere near as good as Lycomings or Continentals. They are an unknown quantity and flying schools are amongst the least likely to take the risks of unproven technology. A few days/weeks of downtime is an annoyance to a private owner, but it is a disaster to a busy school.
Why are Cabair trying to dump their DA40's? They have had so many problems.
These engines have the ability to be a huge step forward, but they aren't there yet. We have looked very closely at getting a DA40, but the reliability puts me off every time.
With regards to the power produced by the Thielert. I flew a DA40 TDI last year and was very surprised by the sluggish nature on the T/O roll. It was fine in the air, but that was in a modern airframe. I shudder to think of the performance in a retro-fit.....
If the manufacturers came up with a 150-200hp version, then they would do some business, but 135hp is just not enough and the SMA engines seem to be too large for your average spamcan.
Why are Cabair trying to dump their DA40's? They have had so many problems.
These engines have the ability to be a huge step forward, but they aren't there yet. We have looked very closely at getting a DA40, but the reliability puts me off every time.
With regards to the power produced by the Thielert. I flew a DA40 TDI last year and was very surprised by the sluggish nature on the T/O roll. It was fine in the air, but that was in a modern airframe. I shudder to think of the performance in a retro-fit.....
If the manufacturers came up with a 150-200hp version, then they would do some business, but 135hp is just not enough and the SMA engines seem to be too large for your average spamcan.
I won't comment on Cabair. but i would suggest that it is not as simple as you have made out.
Our PA28 has had no problems and has been happily flying around with this Thielert engine for over a year now.
Look out for new diesels in the future. They are on there way.
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The occurances notices we all get seem to show a different picture when it comes to reliability. For example, in the lastest issue, there is one report of a DA40 TDI going pop and at the end of the report "The reporter states that this aircraft is now on it's THIRD engine."
That to me doesn't smack of something I'm willing to risk a business on.
I would love to have Jet A powered machines, since the fuel cost saving alone is staggering, I'm just not sure that I want to do a manufacturers field testing for them.
I'm not sure about Cabair now, since I've just seen that press release, but I've also heard from other sources that they are very unhappy with the reliabilty of the things. They've had a fair few "incidents" with them.
I cannot understand why the manufacturers have gone for such daft sizes. If there had been a 160-180hp model straight away, then the take-up would have been far higher than it has been. Why would you spend more money on a less powerful engine that has potential reliability issues hanging over it? The flight school market is always going to be the hardest to break into since there is little money and a deep aversion to taking risks with new technology. So why produce engines that have limited interest to the average private owner? I wouldn't stick 135hp into a 172 or PA28 even with the most efficient prop around.
I'm not anti AVTUR engines, infact I think they are essential to the long-term future of GA, but they aren't there yet and need some serious PR to get over the problems already faced.
That to me doesn't smack of something I'm willing to risk a business on.
I would love to have Jet A powered machines, since the fuel cost saving alone is staggering, I'm just not sure that I want to do a manufacturers field testing for them.
I'm not sure about Cabair now, since I've just seen that press release, but I've also heard from other sources that they are very unhappy with the reliabilty of the things. They've had a fair few "incidents" with them.
I cannot understand why the manufacturers have gone for such daft sizes. If there had been a 160-180hp model straight away, then the take-up would have been far higher than it has been. Why would you spend more money on a less powerful engine that has potential reliability issues hanging over it? The flight school market is always going to be the hardest to break into since there is little money and a deep aversion to taking risks with new technology. So why produce engines that have limited interest to the average private owner? I wouldn't stick 135hp into a 172 or PA28 even with the most efficient prop around.
I'm not anti AVTUR engines, infact I think they are essential to the long-term future of GA, but they aren't there yet and need some serious PR to get over the problems already faced.