Hi Wingless Nut,
You basically need two things in a Piet, an airframe that is build light ie stricly to plans and an engine with mucho TORQUE.
1600 Ford Crossflow with redrive is a very good option as stated by Duck Rogers.
A redrive is nothing more than a Torgue Multiplier ie it increaces the torque of the output shaft (prop flange). That is why a 40Hp Model A with a redrive flew the Piet very sucessfully.
An 0200 probably has not got enough Torgue to swing a large prop.
Stick with what has been proven to work in the past.
As for what prop to use, give Peter de Necker a call.
Kind regards,
Gunter
Best engine for a Piet?
I researched the Mod A Ford engine a while ago and if my memory
does not fail me, it produced in the region of 120nm of torque, so IMHO,
that would be the benchmark.
If a redrive is to be used, I would suggest to multiply the desired
prop rpm with the redrive ratio, and that is the rpm where you
would like your power peak on the motor.
I.E. prop rpm 2500 X 3 redrive ratio = 7500 rpm.
Please feel free to correct me if i'm wrong.
does not fail me, it produced in the region of 120nm of torque, so IMHO,
that would be the benchmark.
If a redrive is to be used, I would suggest to multiply the desired
prop rpm with the redrive ratio, and that is the rpm where you
would like your power peak on the motor.
I.E. prop rpm 2500 X 3 redrive ratio = 7500 rpm.
Please feel free to correct me if i'm wrong.
I would problably do it the other way around, take the engine of choice and see where the peak power is , say 88hp at 6200rpm
your prop would need to run at say 2500rpm, therefore the reduction ratio would be 2.48 to 1.
Remember a plane has a very narrow rpm range to operate in, max rpm for takeof, 75% continuous for cruising which would probably be 5000 to 5500 rpm (I would have to look at the power graph to get this rpm) and at 4000rpm you would be decending.
BTW this is the spec for a 1400 Opel Corsa fuel injected motor. Nice for altitude compensation but not sure of the weight though.
your prop would need to run at say 2500rpm, therefore the reduction ratio would be 2.48 to 1.
Remember a plane has a very narrow rpm range to operate in, max rpm for takeof, 75% continuous for cruising which would probably be 5000 to 5500 rpm (I would have to look at the power graph to get this rpm) and at 4000rpm you would be decending.
BTW this is the spec for a 1400 Opel Corsa fuel injected motor. Nice for altitude compensation but not sure of the weight though.
Greg Perkins
"Remember a plane has a very narrow rpm range to operate in, max rpm for takeof, 75% continuous for cruising which would probably be 5000 to 5500 rpm (I would have to look at the power graph to get this rpm) and at 4000rpm you would be decending. "
Yes Morph is right,
Our aircraft motors work very hard this makes them the "sprinters" of
engines (5000 -5500rpm for 75% power for cruising).
Engines in cars have a much easier time at +- 3000rpm at cruise, so they can be classified as the "joggers".
The above will give you an idea why earo motors do only 1000 - 2000 hours before overhaul is reqired and car motors will last in excess of 500,000km (with regular servicing) which equates to 4100hours.
So to get an aero motor to last long what is needed is low revs (2500-3000rpm) with high torgue at those revs that can swing an appropriate
prop. This would make the engine direct drive thus saving weight and theoretically increacing reliability because you have less parts that can go wrong.
Diesel engines meet these requirements but weight is an issue.
Although the reduced fuel consumption should be able to take you further on less fuel.
No free lunch in aviation.
Yes Morph is right,
Our aircraft motors work very hard this makes them the "sprinters" of
engines (5000 -5500rpm for 75% power for cruising).
Engines in cars have a much easier time at +- 3000rpm at cruise, so they can be classified as the "joggers".
The above will give you an idea why earo motors do only 1000 - 2000 hours before overhaul is reqired and car motors will last in excess of 500,000km (with regular servicing) which equates to 4100hours.
So to get an aero motor to last long what is needed is low revs (2500-3000rpm) with high torgue at those revs that can swing an appropriate
prop. This would make the engine direct drive thus saving weight and theoretically increacing reliability because you have less parts that can go wrong.
Diesel engines meet these requirements but weight is an issue.
Although the reduced fuel consumption should be able to take you further on less fuel.
No free lunch in aviation.
-
Wingless Nut
- Woohoo 100 posts - flying high
- Posts: 108
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- Location: Bellville
Thanks for all the input Guys! I am expecting the plans to arrive shortly. Jan Potgieter in Rustenburg has built his fuselage out of aluminium and I'll find out more about that when he is back from abroad, later this month. I'll certainly look into the Diesel option, simply because I will shortly have a need for a farm-aerie. I reckon i'll just paint it gray, call it "Vaal Piet" and park it in the tractor shed. 
Coenie Otto has fitted a 1.72:1 reduction drive to the 2l diesel engine with a 72" prop pithced at 48". Interesting stuff. By the way, the engine is a gray import turbo diesel which only cost him R4000.00!
Coenie Otto has fitted a 1.72:1 reduction drive to the 2l diesel engine with a 72" prop pithced at 48". Interesting stuff. By the way, the engine is a gray import turbo diesel which only cost him R4000.00!
Sop die Prop!
Interesting you guys should mention diesel,
I am also convinced that the diesel engine is ideal for aircraft,
but not a lot of pilots share my opinion.
If I where to build a piet I would seriously look at the
1700 non turbo corsa diesel, simply because it doesn't have
an electronic engine management system like the turbo version,
Then turbo it to 1 bar, and have the pump recalibrated.
This engine produces 105 nm at 1900 rpm, so you could expect at least
150 nm with the turbo, you can then add a small intercooler if you so
desire.This should be enough to turn a prop direct as this is more or less
the torque a 2 litre vw motor produces, and it is in use
in numerous aircraft on direct drive.
You should however keep in mind that below 5 degrees C
diesel has a tendency to freeze, so you should run it on
jet A1 with two stroke oil at 100/1 ratio, to lubricate the pump.
I am also convinced that the diesel engine is ideal for aircraft,
but not a lot of pilots share my opinion.
If I where to build a piet I would seriously look at the
1700 non turbo corsa diesel, simply because it doesn't have
an electronic engine management system like the turbo version,
Then turbo it to 1 bar, and have the pump recalibrated.
This engine produces 105 nm at 1900 rpm, so you could expect at least
150 nm with the turbo, you can then add a small intercooler if you so
desire.This should be enough to turn a prop direct as this is more or less
the torque a 2 litre vw motor produces, and it is in use
in numerous aircraft on direct drive.
You should however keep in mind that below 5 degrees C
diesel has a tendency to freeze, so you should run it on
jet A1 with two stroke oil at 100/1 ratio, to lubricate the pump.
Hi All,
I found this article on the net written by frenchman who put a diesel engine in an aircraft.
Very interesting, great detail.
Attached is a word doc with the whole article.
Have fun reading
Kind regards,
Gunter
I found this article on the net written by frenchman who put a diesel engine in an aircraft.
Very interesting, great detail.
Attached is a word doc with the whole article.
Have fun reading
Kind regards,
Gunter
- Attachments
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- DIESELIS.doc
- (89 KiB) Downloaded 1218 times
Sorry forgot to put the Dieselis site link into the last post.
http://membres.lycos.fr/dieselis/
Kind regards,
Gunter
http://membres.lycos.fr/dieselis/
Kind regards,
Gunter
Do you have any technical details on this ?Wingless Nut wrote:
Coenie Otto has fitted a 1.72:1 reduction drive to the 2l diesel engine with a 72" prop pithced at 48". Interesting stuff. By the way, the engine is a gray import turbo diesel which only cost him R4000.00!
It would make for some very interesting reading,
espacially for us diesel lovers!!
Hi smallfly,
I have set up a Excel sheet for Engines.
Have a look at it and have fun.
By the way by using diesel engines you can reduce your tank volume by approx 50% because a diesel uses opprox half the amount nof fuel as compared to a petrol engine so you are offsetting the heavier engine weight to a certain extent.
But you probably know this al;ready, am mentioning it for the benefit of people who have not considered diesels for Aircaft use.
Kind regards
Gunter Rostek
I have set up a Excel sheet for Engines.
Have a look at it and have fun.
By the way by using diesel engines you can reduce your tank volume by approx 50% because a diesel uses opprox half the amount nof fuel as compared to a petrol engine so you are offsetting the heavier engine weight to a certain extent.
But you probably know this al;ready, am mentioning it for the benefit of people who have not considered diesels for Aircaft use.
Kind regards
Gunter Rostek
- Attachments
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- Engine Conversion.xls
- (23 KiB) Downloaded 174 times
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