Williams ws. Rankin
Posted by Howard Langdon
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Re: Williams ws. Rankin June 28, 2006 08:44AM |
Registered: 18 years ago Posts: 318 |
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Re: Williams ws. Rankin June 28, 2006 10:54AM |
Registered: 18 years ago Posts: 1,441 |
Andy,
Right now we are going like mad to finish the editing, photo selection and page layout of the Doble book, that is the only thing on my mind right now.
When Chris and I get that more or less done, I will look for the book that briefly described compression and the effects of residual steam and post it.
HOWEVER, I recall it was taking compression as a negative factor and not considering any variation as in the Williams engine. Variable compression depending on the valve chest pressure and, most important, venting back into the valve chest. The others vented to exhaust. That was Williams cute idea along with trying to make the compression high enough to provide a residual steam temperature equal to the inlet condition. Minimum thermal loss at admission.
It also is dependent on initial inlet pressure and cutoff, lots of variables.
Certainly, minimum workable clearance and the highest achievable expansion is desired. Along with minimum radiation and conductive heat losses and valve flow losses.
Bill,
The unaflow does not push the exhaust out of the engine, the counterflow does that.
Most of the books are describing engines with a condenser vacuum. Only one went into engines designed to work against a backpressure.
I think the key word is "Achiveable".
JC
Right now we are going like mad to finish the editing, photo selection and page layout of the Doble book, that is the only thing on my mind right now.
When Chris and I get that more or less done, I will look for the book that briefly described compression and the effects of residual steam and post it.
HOWEVER, I recall it was taking compression as a negative factor and not considering any variation as in the Williams engine. Variable compression depending on the valve chest pressure and, most important, venting back into the valve chest. The others vented to exhaust. That was Williams cute idea along with trying to make the compression high enough to provide a residual steam temperature equal to the inlet condition. Minimum thermal loss at admission.
It also is dependent on initial inlet pressure and cutoff, lots of variables.
Certainly, minimum workable clearance and the highest achievable expansion is desired. Along with minimum radiation and conductive heat losses and valve flow losses.
Bill,
The unaflow does not push the exhaust out of the engine, the counterflow does that.
Most of the books are describing engines with a condenser vacuum. Only one went into engines designed to work against a backpressure.
I think the key word is "Achiveable".
JC
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Re: Williams ws. Rankin June 29, 2006 06:55PM |
Registered: 18 years ago Posts: 1,038 |
Hi Harry
I am not sure how compresson and RPM are going to mix. As I have said before I am shooting for a speed of 15 MPH as the low end of my clearance-cutoff high compression control system. Unlike your engine mine is a direct drive. It will have the vehical initia to carry it through negitive and low torque periods generated by the high compression. I am also planing on using more then 4 expansion chambers. The more expansion chamber with their power strokes spaced evenly though a revoloution also help smoth the torque. There is a traid off though and I don't know what the bast number might be. More expermential work needs to be done. As you know the more pistons you have the higher the surface aree for a gven displacement. So you have to find a balance between heat transfer losses, because of higher surface area, and the higher efficiency of running a low RPM at short cutoffs with/with out high compression.
From my experance though the compression ratio has little to do with it's minum RPM. The Honda's we hoped up and run on methanal had tractor torque cherastrics. You could hardly stall them. They were real thumpers. And were running 18.5:1 compression ratio. The factory engine didn't come close to the low end torque of the hoped engine. We also increassed the displacement from 50 CC to 83 cc with a big bore and stroker kit.
Right now it looks good for a 5:1 speed range. An almost constant expansion ratio from 15 to 75 MPH.
Jim. I have never seen anything along the lines of using clearance and cutoff as a way to control power while maintaining a constant expansion ratio. I mean varing clearance from 3% to 47% while varing cutoff from 31% to 3%. expansion ratio = (clearance+cutoff)/(clearance+1) = (3+31)/(3+100) and (47+3)/(47+100). Not exact the same ratio but close enough for an example of the kind of variation I am trying to get. The idea is thet at 3% cutoff to the 47% cutoff the inlet steam varation is around 3:47 about 1:16. The two engine designs I am looking at for a variable clearance also varies the displacement. The displacement for that clearance is on the order of 2:1. With a constant displacement we are varing the steam usage of the engine around 16:1 compound that with the displacement variation and it doubles to around 32:1. That is basicly the rorque varation (32:1). Ball park example. The speed variation is the square root of that of 5.xx:1 sqrt(32):1 Trying to get around a 3:1 expansion ration in each stage. Note. This has to be a counterflow design as the exhaust close has to vary in order to have compression to inlet pressure.
This is nothing like any old engine idea I have ever read about. At 15 MPH it would be running 3% cutoff and at 75 MPH it at 47% cutoff. Through theat speed range the over expansion ratio is around 27:1.
The analysis of the cycles all look great. But the mechanical implementation is still a bit of a chalange. The main one I am looking at is using two opposed cranks, two pistons per cylander. The power shaft is a seperate shaft coupled to teh two cranks by resolvers. The angles of the cranks in relation the output shaft can be shifted by the resolvers. One would be shifted ahead be some number of degrees while the other is shifted opsitly. One advanced 5 degrees and the other retarded 5 degrees. One leads the other by 10 degrees. If you do the piston position math. The works out to the same as having a single piston and varing it's stroke about it's center. The timming shaft is the output shaft. You have min displacement point is when the two pistons are equal distance (in degrees) from TDC. The thing is that I have a problem with a resolver being able to handle the torque and maintain accuracy. A resolver is the same as a differential only being used differently. For my use it has to be very tight. Very much slop and the clearance wont be controlable.
Then add in that the engine has to big enough to pull 75 MPH at 3% cutoff. The eninge is huge compared to antiques. With a 27:1 expansion ratio we are talking about around a 400 cuin engine.
With the 27:1 expansion ratio(in the cylanders) and 5 to 15 PSI pressure drop to the interstage recievers with an exhauust pressure of 15 to 20 PSIA the inlet pressure is around 1400 PSIA.
The good thing is that with recompression the temperature only has to be around 800 F to avoid condensation. That is with ideal compression cycles.
Crazy maybe. Don't know till it's tried.
Andy
I am not sure how compresson and RPM are going to mix. As I have said before I am shooting for a speed of 15 MPH as the low end of my clearance-cutoff high compression control system. Unlike your engine mine is a direct drive. It will have the vehical initia to carry it through negitive and low torque periods generated by the high compression. I am also planing on using more then 4 expansion chambers. The more expansion chamber with their power strokes spaced evenly though a revoloution also help smoth the torque. There is a traid off though and I don't know what the bast number might be. More expermential work needs to be done. As you know the more pistons you have the higher the surface aree for a gven displacement. So you have to find a balance between heat transfer losses, because of higher surface area, and the higher efficiency of running a low RPM at short cutoffs with/with out high compression.
From my experance though the compression ratio has little to do with it's minum RPM. The Honda's we hoped up and run on methanal had tractor torque cherastrics. You could hardly stall them. They were real thumpers. And were running 18.5:1 compression ratio. The factory engine didn't come close to the low end torque of the hoped engine. We also increassed the displacement from 50 CC to 83 cc with a big bore and stroker kit.
Right now it looks good for a 5:1 speed range. An almost constant expansion ratio from 15 to 75 MPH.
Jim. I have never seen anything along the lines of using clearance and cutoff as a way to control power while maintaining a constant expansion ratio. I mean varing clearance from 3% to 47% while varing cutoff from 31% to 3%. expansion ratio = (clearance+cutoff)/(clearance+1) = (3+31)/(3+100) and (47+3)/(47+100). Not exact the same ratio but close enough for an example of the kind of variation I am trying to get. The idea is thet at 3% cutoff to the 47% cutoff the inlet steam varation is around 3:47 about 1:16. The two engine designs I am looking at for a variable clearance also varies the displacement. The displacement for that clearance is on the order of 2:1. With a constant displacement we are varing the steam usage of the engine around 16:1 compound that with the displacement variation and it doubles to around 32:1. That is basicly the rorque varation (32:1). Ball park example. The speed variation is the square root of that of 5.xx:1 sqrt(32):1 Trying to get around a 3:1 expansion ration in each stage. Note. This has to be a counterflow design as the exhaust close has to vary in order to have compression to inlet pressure.
This is nothing like any old engine idea I have ever read about. At 15 MPH it would be running 3% cutoff and at 75 MPH it at 47% cutoff. Through theat speed range the over expansion ratio is around 27:1.
The analysis of the cycles all look great. But the mechanical implementation is still a bit of a chalange. The main one I am looking at is using two opposed cranks, two pistons per cylander. The power shaft is a seperate shaft coupled to teh two cranks by resolvers. The angles of the cranks in relation the output shaft can be shifted by the resolvers. One would be shifted ahead be some number of degrees while the other is shifted opsitly. One advanced 5 degrees and the other retarded 5 degrees. One leads the other by 10 degrees. If you do the piston position math. The works out to the same as having a single piston and varing it's stroke about it's center. The timming shaft is the output shaft. You have min displacement point is when the two pistons are equal distance (in degrees) from TDC. The thing is that I have a problem with a resolver being able to handle the torque and maintain accuracy. A resolver is the same as a differential only being used differently. For my use it has to be very tight. Very much slop and the clearance wont be controlable.
Then add in that the engine has to big enough to pull 75 MPH at 3% cutoff. The eninge is huge compared to antiques. With a 27:1 expansion ratio we are talking about around a 400 cuin engine.
With the 27:1 expansion ratio(in the cylanders) and 5 to 15 PSI pressure drop to the interstage recievers with an exhauust pressure of 15 to 20 PSIA the inlet pressure is around 1400 PSIA.
The good thing is that with recompression the temperature only has to be around 800 F to avoid condensation. That is with ideal compression cycles.
Crazy maybe. Don't know till it's tried.
Andy
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Re: Williams ws. Rankin June 29, 2006 10:44PM |
Registered: 18 years ago Posts: 1,249 |
Hello Andy,
With 800 degrees inlet temp what kind of efficiency are you calculating?
I am looking at 1200 deg at the end of cutoff to pull off 30%.
Also for a 400 ci engine what HP at what RPMs is contemplated? That would be final stage displacement, or total?
I think I might be tempted to investigate an hydroulic resolver that rotates with one crank. That way if something breaks the engine would still run.
Best -------- Bill G.
With 800 degrees inlet temp what kind of efficiency are you calculating?
I am looking at 1200 deg at the end of cutoff to pull off 30%.
Also for a 400 ci engine what HP at what RPMs is contemplated? That would be final stage displacement, or total?
I think I might be tempted to investigate an hydroulic resolver that rotates with one crank. That way if something breaks the engine would still run.
Best -------- Bill G.
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Re: Williams ws. Rankin June 30, 2006 09:46AM |
Registered: 18 years ago Posts: 835 |
Hi Andy,
As you spoke about engine friction the Cyclone is only 38cu in and on a single throw crank. with 6 cyl it doesn't have to have as long a cutoff for self starting torgue. Compression does come into play at self starting,how can you rely on venicle inertia when there is none. What we are using is piston inertia where things are in balance. A low rpm engine with massive torque has to have a a very strong transfer of power. The smaller engine with a longer power band is a better way to go, A large engine will weigh more and take up more space and cost more to build, all of these things are efficencys also. Just stirring the pot.
Harry
As you spoke about engine friction the Cyclone is only 38cu in and on a single throw crank. with 6 cyl it doesn't have to have as long a cutoff for self starting torgue. Compression does come into play at self starting,how can you rely on venicle inertia when there is none. What we are using is piston inertia where things are in balance. A low rpm engine with massive torque has to have a a very strong transfer of power. The smaller engine with a longer power band is a better way to go, A large engine will weigh more and take up more space and cost more to build, all of these things are efficencys also. Just stirring the pot.
Harry
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Re: Williams ws. Rankin June 30, 2006 10:52AM |
Registered: 18 years ago Posts: 1,038 |
Hi Bill.
The 400 ci is a rough estimate. As I am trying to match up the efficient power range of the engine to a specific speed range it is very important to size the engine right. The 400 ci is total for all stages. After analyzing Herry's super critical engine there could be some advantage to going to higher pressure, have more inter-stage pressure drop with same over all expansion ratio. The power density would reduce engine size. The IFC-67 steam property formulation's limited range of temperature prevent the analysis at this time. I am working on the IAPWS-95 formulations. The IFC-67 and IAPWS-97 formulations divide the space into regions where diferent formula are used. The IFC-67 has 4 regions. The IAPWS-97 adds a fifth high temperature region with limited pressure range. Some of the regions use formula based on Gibbs specific free energy equations taking pressure and temperature as arguments while others use the Helmholtz specific free energy equations taking temperature and density as arguments. There discontinuities along the boundries of the regions. The discontinuities don't cause to much of problem for static cycle calculation. But for simulations, where expansion crosses a broundry for example, the discontinuities cause some sigificant problems. The limited temperature range if the industrial (IFC-67 and IAPWS-97) formulation is also a problem. Even if you never have a result over the temperature limit. The algorithm of searching for that result can get into a situation where an estimated temperature is over the limit. The upper temperature limit is around 1480 F for the industrial formulations. For example you have specific entropy and specific volume doing an expansion and you wont to find the state point. And the point is close to a region boundry. On wone sode you have formula taking arguments of pressure and temperature while on the other you have formula taking temperature and density. You have to solve these for the given entropy and specific volume. Real interesting problem solving these sets of equaions. The scientific formula using one set of equation all derived from one Helmholtz specific free energy equations makes the problem a lot simpler. On the other hand it as not an easy task programming a 56 term polynomial. Just entering all the constants correctly is a task. There like 3,4, 7 and 8 constants in the terms. Actually there more. There is two parts to the Helmholtz specific free energy equation for the IAPWS-95 formula. It consists of an ideal gas part (8 terms) and a real gas residual part (56 terms). The actual property formula are functions of derivities of the two Helmholtz specific free energy equations parts. You wind up with six function for the Helmholtz and it's partial diferentials. You have the Helmholtz function. It's derivitive with respect to temperature. It's derivitive with respect to density. It's second order derivitive with respect to temperature. It's second order derivitive with respect to density. And it's second order derivitive with respect to density, temperature. It's dificault to debug. Just one digit typo in a constant can result in a huge error. But because of the nature of the terms. Their ignificance varies. So that one digit being off may only effect a small region of the space covered. It could only effect the result when close to the critical point for example and the term it is in could be insignificant every else. I have just reciently took to generating an array holding each term. Did MathCad worksheets for the formulations doing the same and compared the results term by term to find problem. Found quite a few. Still working on them though. Don't know what happened but after correcting bugs found on gas and liquid test points the saturation test points are comming out wrong now. The solver goes into a runaway mode now. Actually I didn't find any constant typos. It was grouping errors entering the diferential functions. The derivitave terms are 4 to 10 lines of C code.
Andy
The 400 ci is a rough estimate. As I am trying to match up the efficient power range of the engine to a specific speed range it is very important to size the engine right. The 400 ci is total for all stages. After analyzing Herry's super critical engine there could be some advantage to going to higher pressure, have more inter-stage pressure drop with same over all expansion ratio. The power density would reduce engine size. The IFC-67 steam property formulation's limited range of temperature prevent the analysis at this time. I am working on the IAPWS-95 formulations. The IFC-67 and IAPWS-97 formulations divide the space into regions where diferent formula are used. The IFC-67 has 4 regions. The IAPWS-97 adds a fifth high temperature region with limited pressure range. Some of the regions use formula based on Gibbs specific free energy equations taking pressure and temperature as arguments while others use the Helmholtz specific free energy equations taking temperature and density as arguments. There discontinuities along the boundries of the regions. The discontinuities don't cause to much of problem for static cycle calculation. But for simulations, where expansion crosses a broundry for example, the discontinuities cause some sigificant problems. The limited temperature range if the industrial (IFC-67 and IAPWS-97) formulation is also a problem. Even if you never have a result over the temperature limit. The algorithm of searching for that result can get into a situation where an estimated temperature is over the limit. The upper temperature limit is around 1480 F for the industrial formulations. For example you have specific entropy and specific volume doing an expansion and you wont to find the state point. And the point is close to a region boundry. On wone sode you have formula taking arguments of pressure and temperature while on the other you have formula taking temperature and density. You have to solve these for the given entropy and specific volume. Real interesting problem solving these sets of equaions. The scientific formula using one set of equation all derived from one Helmholtz specific free energy equations makes the problem a lot simpler. On the other hand it as not an easy task programming a 56 term polynomial. Just entering all the constants correctly is a task. There like 3,4, 7 and 8 constants in the terms. Actually there more. There is two parts to the Helmholtz specific free energy equation for the IAPWS-95 formula. It consists of an ideal gas part (8 terms) and a real gas residual part (56 terms). The actual property formula are functions of derivities of the two Helmholtz specific free energy equations parts. You wind up with six function for the Helmholtz and it's partial diferentials. You have the Helmholtz function. It's derivitive with respect to temperature. It's derivitive with respect to density. It's second order derivitive with respect to temperature. It's second order derivitive with respect to density. And it's second order derivitive with respect to density, temperature. It's dificault to debug. Just one digit typo in a constant can result in a huge error. But because of the nature of the terms. Their ignificance varies. So that one digit being off may only effect a small region of the space covered. It could only effect the result when close to the critical point for example and the term it is in could be insignificant every else. I have just reciently took to generating an array holding each term. Did MathCad worksheets for the formulations doing the same and compared the results term by term to find problem. Found quite a few. Still working on them though. Don't know what happened but after correcting bugs found on gas and liquid test points the saturation test points are comming out wrong now. The solver goes into a runaway mode now. Actually I didn't find any constant typos. It was grouping errors entering the diferential functions. The derivitave terms are 4 to 10 lines of C code.
Andy
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Re: Williams ws. Rankin June 30, 2006 11:28AM |
Registered: 18 years ago Posts: 1,038 |
Hi Herry
I spoke about engine friction? Where?
Any way my low end of speed range, for the contant expansion cycle, as stated was 15 MPH. I talked about the change over to throttling below that in another post. At 0 RPM there is no compression and some throttling method is going to be used. It may be a palsed inlet valve deal, Or true throttling at the engine. Going to try opening the inlet for very short time to effect a throttling. but if that doesn't work will have to use throttling. Or a combination of a fixed throttl and palsed valve opening. I.E. A valved large opening to the steam chest from the steam supply and a restricted passage around the valve. I do plan for it to be self starting.
As you increase power past the high end of the constant expansion range the compression would reduce down to no compression and then the cutoff would increase as you increase power.
RPM is a big if. From all the data I have it looks that a steam engine looses torque vary rapidly above 1000 RPM. And generally is down to 30% by 1600 RPM. Now I know you are running at a lot higher RPM and so did Jay Carter. But I have no data from you or Jay on what the torque curve looks like for your engines. I don't know exactly whats causing such a drastic power drop off. And your reluctance to share such data leaves me with some doubt that you have solved that problem.
I do know that the speed of sound in the substance is a limit on expansion rate. It limits the flow rate from a high pressure to low pressure through a port. I havn't really looked at this much. Just sturing the pot.
Andy
I spoke about engine friction? Where?
Any way my low end of speed range, for the contant expansion cycle, as stated was 15 MPH. I talked about the change over to throttling below that in another post. At 0 RPM there is no compression and some throttling method is going to be used. It may be a palsed inlet valve deal, Or true throttling at the engine. Going to try opening the inlet for very short time to effect a throttling. but if that doesn't work will have to use throttling. Or a combination of a fixed throttl and palsed valve opening. I.E. A valved large opening to the steam chest from the steam supply and a restricted passage around the valve. I do plan for it to be self starting.
As you increase power past the high end of the constant expansion range the compression would reduce down to no compression and then the cutoff would increase as you increase power.
RPM is a big if. From all the data I have it looks that a steam engine looses torque vary rapidly above 1000 RPM. And generally is down to 30% by 1600 RPM. Now I know you are running at a lot higher RPM and so did Jay Carter. But I have no data from you or Jay on what the torque curve looks like for your engines. I don't know exactly whats causing such a drastic power drop off. And your reluctance to share such data leaves me with some doubt that you have solved that problem.
I do know that the speed of sound in the substance is a limit on expansion rate. It limits the flow rate from a high pressure to low pressure through a port. I havn't really looked at this much. Just sturing the pot.
Andy
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Re: Williams ws. Rankin June 30, 2006 12:28PM |
Registered: 18 years ago Posts: 835 |
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Re: Williams ws. Rankin June 30, 2006 08:20PM |
Registered: 18 years ago Posts: 1,249 |
Hello,
Ya know Andy that is a question that needs a bit more kicking around. Why would a steam engine loose so much torque at such a low RPM?
It stands to reason that valve and port restrictions would contribute a lot to the mix but what exactly? It would be of great use to have a Williams engine on the test stand to find out.
Is there a small sensor that can give the speed of flow past it? Also what is the valve time in crank angle from full open to full close or visa versa with the Williams and other engines?
Most of the steam engines I have seen just look restricted to me.
Thank You --------- Bill G.
Ya know Andy that is a question that needs a bit more kicking around. Why would a steam engine loose so much torque at such a low RPM?
It stands to reason that valve and port restrictions would contribute a lot to the mix but what exactly? It would be of great use to have a Williams engine on the test stand to find out.
Is there a small sensor that can give the speed of flow past it? Also what is the valve time in crank angle from full open to full close or visa versa with the Williams and other engines?
Most of the steam engines I have seen just look restricted to me.
Thank You --------- Bill G.
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Re: Williams ws. Rankin July 01, 2006 11:07AM |
Registered: 18 years ago Posts: 1,441 |
Bill,
Torque diminishes with increasing rpm due to falling BMEP. Caused by valve flow losses, cutoff position, and also due to increasing friction of the moving parts.
Steam engine valving is very restricted compared to IC engines, because no one seems to have paid attention to this with high rpm engines. Automotive steam engines were classically low rpm, Stanley, White, Doble, et al. This then, was not considered to be a failing; but actually an advantage, because low rpm engines were considered the most desirable, due to their wanting silence and smooth running.
IC engines, unless supercharged, need to suck in the mixture with minimium losses in order to maintain the power level. Thus four valves and as large as possible. Steam engines have pressure available in the valve chamber and are not operating under this handicap.
The questions are: 1) What constitutes high rpm, 1,000 or 5,000? 2) Why would one wish to make a high speed steam engine, when the torque vs. load match favors modest speed to give good performance? Thus, also, a good steamer has a two speed system.
JC
Torque diminishes with increasing rpm due to falling BMEP. Caused by valve flow losses, cutoff position, and also due to increasing friction of the moving parts.
Steam engine valving is very restricted compared to IC engines, because no one seems to have paid attention to this with high rpm engines. Automotive steam engines were classically low rpm, Stanley, White, Doble, et al. This then, was not considered to be a failing; but actually an advantage, because low rpm engines were considered the most desirable, due to their wanting silence and smooth running.
IC engines, unless supercharged, need to suck in the mixture with minimium losses in order to maintain the power level. Thus four valves and as large as possible. Steam engines have pressure available in the valve chamber and are not operating under this handicap.
The questions are: 1) What constitutes high rpm, 1,000 or 5,000? 2) Why would one wish to make a high speed steam engine, when the torque vs. load match favors modest speed to give good performance? Thus, also, a good steamer has a two speed system.
JC
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Re: Williams ws. Rankin July 01, 2006 11:14AM |
Registered: 18 years ago Posts: 835 |
Hi Bill, Andy
I am a firm beliver in Hi pressure and short cut off. Long cut off and low pressure means that the flow is on the fast side of the piston stroke where it takes a large valve and and larger piston area, a lot to fill.
Jay Carter operated at 5000rpm. Of course hp and torque are equal at 5250. He told me he was a beliver in high rpm. Of course he was running a bump valve and they operate well that way. I could be wrong but his 43cu in eng was 90hp at 5000rpm at 2000psi. torque would be 94.5lbs.at 5000. The Cyclone of course has more variables but he same holds true at the higher rpm. It operates at 3600rpm where 92hp = 134lbs torque. Jay used a throttle valve for contol whereas we are using cutoff,maintaining constant temperature and preasure.
We still use our rule of thumb foumula on this type of short cut off eng and it appears to be close.( of course this is not all we use)
Jay carter eng 43cu in X 5000rpm X.06 cuttoff / 283 = 45.5 at 1000psiX2= 91hp
cyclone ene 37.7cu in X 3600 X .06cutoff / 283 = 28.77at 3200psiX3.2 = 92hp
(not to compare engines but the simple formula)
Jay is a realy smart guy, learned a lot from him.It pays to go to the SACA meets.
Harry
I am a firm beliver in Hi pressure and short cut off. Long cut off and low pressure means that the flow is on the fast side of the piston stroke where it takes a large valve and and larger piston area, a lot to fill.
Jay Carter operated at 5000rpm. Of course hp and torque are equal at 5250. He told me he was a beliver in high rpm. Of course he was running a bump valve and they operate well that way. I could be wrong but his 43cu in eng was 90hp at 5000rpm at 2000psi. torque would be 94.5lbs.at 5000. The Cyclone of course has more variables but he same holds true at the higher rpm. It operates at 3600rpm where 92hp = 134lbs torque. Jay used a throttle valve for contol whereas we are using cutoff,maintaining constant temperature and preasure.
We still use our rule of thumb foumula on this type of short cut off eng and it appears to be close.( of course this is not all we use)
Jay carter eng 43cu in X 5000rpm X.06 cuttoff / 283 = 45.5 at 1000psiX2= 91hp
cyclone ene 37.7cu in X 3600 X .06cutoff / 283 = 28.77at 3200psiX3.2 = 92hp
(not to compare engines but the simple formula)
Jay is a realy smart guy, learned a lot from him.It pays to go to the SACA meets.
Harry
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Re: Williams ws. Rankin July 01, 2006 04:26PM |
Registered: 18 years ago Posts: 1,249 |
Hello Jim and Harry,
OK then, my high speed and large opening valve system should much take care of the torque dropoff problem. Next is that my transfer ports and final exhaust ports are open an extreamely long time so restriction should be minimalized there also.
Jim, there is an additional advantage to having valves and ports that will go to high RPMs. That is in limiting wiredrawing. I suspect that an engine that is starting to loose torque at 1000 RPM is also really loosing efficiency to wiredrawing. My valve system will give extreamely fast opening and closing times of 15 degrees crank rotation up to about 4000 RPMs. Compare that to a very fast racing engine to see what I did. The inlet valves effective opening is 7/8 diameter by 0.20 inches lift, for a port area of 0.55 inches, cutoff and advance totally controlable. The steam chest adds the reflected pressure waves to ram the steam in at any RPM.
This then brings us back to the basic question of why use high RPM in a steam engine, assuming there is enough boiler to feed the engine at high RPM to take advantage? I think for average cruising low RPMs and a higher gear ratio would be the norm. When one wished to put their foot to it, then downshift and go, like a passing gear. This would allow a smaller displacement engine to do the job. I am not by any means stuck on this particular idea however. Various steam racing engines could take advantage of the high RPMs for the fun of it.
The other thing of course is 3600 RPM works for generators so a duel speed genset that can kick up from 1800 to 3600 when demand goes up might be useful.
Best ----------- Bill G.
OK then, my high speed and large opening valve system should much take care of the torque dropoff problem. Next is that my transfer ports and final exhaust ports are open an extreamely long time so restriction should be minimalized there also.
Jim, there is an additional advantage to having valves and ports that will go to high RPMs. That is in limiting wiredrawing. I suspect that an engine that is starting to loose torque at 1000 RPM is also really loosing efficiency to wiredrawing. My valve system will give extreamely fast opening and closing times of 15 degrees crank rotation up to about 4000 RPMs. Compare that to a very fast racing engine to see what I did. The inlet valves effective opening is 7/8 diameter by 0.20 inches lift, for a port area of 0.55 inches, cutoff and advance totally controlable. The steam chest adds the reflected pressure waves to ram the steam in at any RPM.
This then brings us back to the basic question of why use high RPM in a steam engine, assuming there is enough boiler to feed the engine at high RPM to take advantage? I think for average cruising low RPMs and a higher gear ratio would be the norm. When one wished to put their foot to it, then downshift and go, like a passing gear. This would allow a smaller displacement engine to do the job. I am not by any means stuck on this particular idea however. Various steam racing engines could take advantage of the high RPMs for the fun of it.
The other thing of course is 3600 RPM works for generators so a duel speed genset that can kick up from 1800 to 3600 when demand goes up might be useful.
Best ----------- Bill G.
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Re: Williams ws. Rankin July 02, 2006 09:19PM |
Registered: 18 years ago Posts: 318 |
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Re: Williams ws. Rankin July 02, 2006 11:03PM |
Registered: 18 years ago Posts: 1,249 |
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Re: Williams ws. Rankin July 03, 2006 10:05AM |
Registered: 18 years ago Posts: 1,441 |
Bill, Harry,
I guess the real question in my mind, is why would one want to go to high speeds?
The great charm of the steamer is that awsome low speed torque and the resulting good acceleration. Torque gives accleration, horsepower maintains road speed.
You don't need high torque then, really only wanted for acceleration and rapid hill climbing. It is that wonderful flexibility that is the charm of the steamer.
When a 6300 pound Doble, E-14, could blow the door handles off an SJ Duesenberg and a well souped up J (9-1 compression, Esky cams, four carburetors) like they were parked, both being wound up to the hilt, and all at low speeds, where would high engine speeds come into it? I know, I was in the car when these two races happened. Also my race, E-23, with a loaded Pontiac GTO up the Mt. Rose hill going to Lake Tahoe from Carson City, he didn't have a chance.
All this performance in an old crate was due to their both having draft boosters.
High speeds only increase he flow losses and engine friction and introduce serious valve gear problems, it just is not needed.
Step back for a moment and consider the inlet valve operation. One can use three things for cutoff control. Vary lift, or have constant lift; but varying opening timing. Or, use two valves in series, one for timing and one for cutoff. These all have been done many times previously, nothing new here. Then decide which one suites your purpose.
Wire drawing is a serious loss and must be avoided.
Thus my settling on three cylinders with modest cutoff; but second stage expansion with a turbine, also done before with grand success. Smaller and lighter than a piston compound, less of a balance problem and higher efficiency.
It is not a matter of inventing something new; but one of selecting good previous designs and incorporating them into one engine.
Howard,
I knew Alick Clarkson very well, having many spirited discussions with him. He was a very well educated man and most charming, with tons of experience.
He made both a V-4 and a V-6 car steam engines. His rotary valves fatally leaked after only an hour or two, needed massive lubrication to even live that long, and quickly froze up. Both were single acting unaflow, if I recall correctly.
He even made a small central admission Lysholm type engine after he abandoned the idea of rotary valves.
There may be photos and information on these in old SACA Journals.
JC
I guess the real question in my mind, is why would one want to go to high speeds?
The great charm of the steamer is that awsome low speed torque and the resulting good acceleration. Torque gives accleration, horsepower maintains road speed.
You don't need high torque then, really only wanted for acceleration and rapid hill climbing. It is that wonderful flexibility that is the charm of the steamer.
When a 6300 pound Doble, E-14, could blow the door handles off an SJ Duesenberg and a well souped up J (9-1 compression, Esky cams, four carburetors) like they were parked, both being wound up to the hilt, and all at low speeds, where would high engine speeds come into it? I know, I was in the car when these two races happened. Also my race, E-23, with a loaded Pontiac GTO up the Mt. Rose hill going to Lake Tahoe from Carson City, he didn't have a chance.
All this performance in an old crate was due to their both having draft boosters.
High speeds only increase he flow losses and engine friction and introduce serious valve gear problems, it just is not needed.
Step back for a moment and consider the inlet valve operation. One can use three things for cutoff control. Vary lift, or have constant lift; but varying opening timing. Or, use two valves in series, one for timing and one for cutoff. These all have been done many times previously, nothing new here. Then decide which one suites your purpose.
Wire drawing is a serious loss and must be avoided.
Thus my settling on three cylinders with modest cutoff; but second stage expansion with a turbine, also done before with grand success. Smaller and lighter than a piston compound, less of a balance problem and higher efficiency.
It is not a matter of inventing something new; but one of selecting good previous designs and incorporating them into one engine.
Howard,
I knew Alick Clarkson very well, having many spirited discussions with him. He was a very well educated man and most charming, with tons of experience.
He made both a V-4 and a V-6 car steam engines. His rotary valves fatally leaked after only an hour or two, needed massive lubrication to even live that long, and quickly froze up. Both were single acting unaflow, if I recall correctly.
He even made a small central admission Lysholm type engine after he abandoned the idea of rotary valves.
There may be photos and information on these in old SACA Journals.
JC
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Re: Williams ws. Rankin July 03, 2006 10:45AM |
Registered: 18 years ago Posts: 835 |
Hi Jim,
I certainly agree with you about the charm of the low speed engine, however in my opinion a steam engine is a pump and rpm is related to piston speed. More smaller pistons I donot have to have as long as a cutoff for high torque and the engine is much smaller, the wheel torque is in the axel ratio. It has been my experiance that the low speed high torque engines require a much larger gear box.
Short cut off ,high preasure,high temp less losses. A much smaller engine with less weight. The cyclone engine with the heat exchanger (boiler) and condencer are about the same size and weight as the Doble boiler alone. A lighter car can also be more efficent. 6200lbs is a realy fast truck. My Excursion is only 5200lbs. And has a V10 engine. Your Doble probaly gets better milage.Amazing what a good steam engine can do. and polution free.
The 6cyl Cyclone is 24"high X 27" round
Harry
I certainly agree with you about the charm of the low speed engine, however in my opinion a steam engine is a pump and rpm is related to piston speed. More smaller pistons I donot have to have as long as a cutoff for high torque and the engine is much smaller, the wheel torque is in the axel ratio. It has been my experiance that the low speed high torque engines require a much larger gear box.
Short cut off ,high preasure,high temp less losses. A much smaller engine with less weight. The cyclone engine with the heat exchanger (boiler) and condencer are about the same size and weight as the Doble boiler alone. A lighter car can also be more efficent. 6200lbs is a realy fast truck. My Excursion is only 5200lbs. And has a V10 engine. Your Doble probaly gets better milage.Amazing what a good steam engine can do. and polution free.
The 6cyl Cyclone is 24"high X 27" round
Harry
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Re: Williams ws. Rankin July 03, 2006 04:41PM |
Registered: 18 years ago Posts: 1,249 |
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Re: Williams ws. Rankin July 03, 2006 08:55PM |
Registered: 18 years ago Posts: 318 |
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Re: Williams ws. Rankin July 03, 2006 09:41PM |
Registered: 18 years ago Posts: 171 |
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Re: Williams ws. Rankin July 03, 2006 11:19PM |
Registered: 18 years ago Posts: 1,249 |
Hello,
Nomenclature question.
When talking of piston speed, is it common practice to mean the average speed for the distance of the stroke or the maximum speed roughly in the middle of the stroke?
Thank You --------- Bill G.
PS. When considering engine RPMs lets not forget the hydroplane or the salt flats. A lot has been learned about IC engines from pushing them to the max.
Nomenclature question.
When talking of piston speed, is it common practice to mean the average speed for the distance of the stroke or the maximum speed roughly in the middle of the stroke?
Thank You --------- Bill G.
PS. When considering engine RPMs lets not forget the hydroplane or the salt flats. A lot has been learned about IC engines from pushing them to the max.
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Re: Williams ws. Rankin July 04, 2006 10:44AM |
Registered: 18 years ago Posts: 1,441 |
Harry,
It all depends on what characteristics you want in a new steam car. Personally, I much prefer a larger displacement and slower speed. Not huge, just larger like a three cylinder 3-1/2"-4" X 4"-4 1/2", or so. So far, the high speed steam engines I have seen and heard, all sound like wild outboards and I don't like that racket, I want silence and smooth running from zero on up. The burners make enough noise, although a nice "Power Roar" as Abner once called it.
It all depends on the vehicle that the system is installed in. It also isn't a problem of just the engine weight; but making the rest of the system light weight. The Lamont with extended surface tubing sure does help a lot.
The gearing is no problem at all and packaged with the differential.
No, I'll bet your V-10 gets a lot better milage than the Doble, it is lucky to see 8 mpg, and steaming up sucks up a surprising lot of fuel.
Bill,
This dual inlet valve business was in some SAE paper and the engine was designed in England.
Both were in tandem; but what I don't like about it is the added clearance volume they bring along with the design. This is a subject that need lots of attention in a new car engine.
Perhaps someone can tell you on this post where that paper can be found, it came up before.
As to Bonneville or marine use, play with the gearing and don't make the engine run as fast as possible, no need for that.
Howard,
That Pontiac I once raced was the hottest GTO in the catalog. 427 I think, hot cam, triple carbs, four speed and a limited slip 4:11 rear end and big tires.
I am not surprised at all that your F beat one in a drag race.
JC
It all depends on what characteristics you want in a new steam car. Personally, I much prefer a larger displacement and slower speed. Not huge, just larger like a three cylinder 3-1/2"-4" X 4"-4 1/2", or so. So far, the high speed steam engines I have seen and heard, all sound like wild outboards and I don't like that racket, I want silence and smooth running from zero on up. The burners make enough noise, although a nice "Power Roar" as Abner once called it.
It all depends on the vehicle that the system is installed in. It also isn't a problem of just the engine weight; but making the rest of the system light weight. The Lamont with extended surface tubing sure does help a lot.
The gearing is no problem at all and packaged with the differential.
No, I'll bet your V-10 gets a lot better milage than the Doble, it is lucky to see 8 mpg, and steaming up sucks up a surprising lot of fuel.
Bill,
This dual inlet valve business was in some SAE paper and the engine was designed in England.
Both were in tandem; but what I don't like about it is the added clearance volume they bring along with the design. This is a subject that need lots of attention in a new car engine.
Perhaps someone can tell you on this post where that paper can be found, it came up before.
As to Bonneville or marine use, play with the gearing and don't make the engine run as fast as possible, no need for that.
Howard,
That Pontiac I once raced was the hottest GTO in the catalog. 427 I think, hot cam, triple carbs, four speed and a limited slip 4:11 rear end and big tires.
I am not surprised at all that your F beat one in a drag race.
JC
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Re: Williams ws. Rankin July 04, 2006 09:11PM |
Registered: 18 years ago Posts: 318 |
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Re: Williams ws. Rankin July 05, 2006 11:57PM |
Registered: 18 years ago Posts: 1,249 |
Well Guys,
I guess I'll just go ahead then and design an "ultimate" valve system and if it's way over the top we can always back down on it. Right now I'm cutting the rockers and valve stems out of brass. Having the little pieces in hand makes some complicated visualizing go away. Not too horribly accurate using drills and files in the living room but its comming out better than one might think.
For instance theoretically a curved surface on the rocker seemed as if it might add strength. Having the small piece in hand and not just on paper showed that a curved surface was ridiculous.
Brass is nice to work with for modeling as it is strong, solderable, silver solderable, glueable and cuts and files easily. I think I bought every size of brass tube in the hobby section of the hardware store, other brass pieces of plumbing are also now found in my top desk drawer.
I am hopeing to soon have the valve train drawings finished to the point of getting a single cylinder head machined and tested.
Best ----------- Bill G.
I guess I'll just go ahead then and design an "ultimate" valve system and if it's way over the top we can always back down on it. Right now I'm cutting the rockers and valve stems out of brass. Having the little pieces in hand makes some complicated visualizing go away. Not too horribly accurate using drills and files in the living room but its comming out better than one might think.
For instance theoretically a curved surface on the rocker seemed as if it might add strength. Having the small piece in hand and not just on paper showed that a curved surface was ridiculous.
Brass is nice to work with for modeling as it is strong, solderable, silver solderable, glueable and cuts and files easily. I think I bought every size of brass tube in the hobby section of the hardware store, other brass pieces of plumbing are also now found in my top desk drawer.
I am hopeing to soon have the valve train drawings finished to the point of getting a single cylinder head machined and tested.
Best ----------- Bill G.
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Re: Williams ws. Rankin July 06, 2006 03:47PM |
Registered: 18 years ago Posts: 1,038 |
Hi Jim
There are good reasions for higher RPM. Smaller engine and more speed range. But I don't wont to lose the low end torque and self starting. I just wont to be able to get a good spead range with great acceleration and not have a multi gear transmission to do it.
As an example say we have two engines, one engine is half the displacement of the other and reves twice as high but having identical torque curve profiles. That is the torque of the small engine at twice the rpm is half the large engine. We gear them 2 to 1 so we have identical torque at a given speed. What advantage do we have? For one the small engine reving higher for a given speed can run at a lower speed on short cutoff before it's power palses are felt by the passengers. It cuould get better efficiency over a varing driving cycle. The small engine is half the size. Leaving more boiler space or the vehical could be smaller more arodynamic and lighter.
I am not so sure that an efficient high RPM engine can be built though. The S.E.S. enginewas designed for good breathing and it't torque droped off the same as the old antique steamers. If anything the S.E.S. torque begins at a lower RPM. And with tuned ports even earler. Just what is causing the torque to drop off. If flow restrictions is the cause of the torque off. The S.E.S. engine, having streamlined porting ahead of the valves, should have reduced the flow problems and should be showing less drop off. That is not the case.
At 2800 RPM the S.E.S. engine untuned has around 20% of it's 500 RPM torque. With tunning at 2800 RPM it increasses to 30%. The peak HP is moved from around 1200 RPM to around 1600 RPM. There is also around a 15% increase in peak HP. That kind of improvement could give an increased speed range.
Andy
There are good reasions for higher RPM. Smaller engine and more speed range. But I don't wont to lose the low end torque and self starting. I just wont to be able to get a good spead range with great acceleration and not have a multi gear transmission to do it.
As an example say we have two engines, one engine is half the displacement of the other and reves twice as high but having identical torque curve profiles. That is the torque of the small engine at twice the rpm is half the large engine. We gear them 2 to 1 so we have identical torque at a given speed. What advantage do we have? For one the small engine reving higher for a given speed can run at a lower speed on short cutoff before it's power palses are felt by the passengers. It cuould get better efficiency over a varing driving cycle. The small engine is half the size. Leaving more boiler space or the vehical could be smaller more arodynamic and lighter.
I am not so sure that an efficient high RPM engine can be built though. The S.E.S. enginewas designed for good breathing and it't torque droped off the same as the old antique steamers. If anything the S.E.S. torque begins at a lower RPM. And with tuned ports even earler. Just what is causing the torque to drop off. If flow restrictions is the cause of the torque off. The S.E.S. engine, having streamlined porting ahead of the valves, should have reduced the flow problems and should be showing less drop off. That is not the case.
At 2800 RPM the S.E.S. engine untuned has around 20% of it's 500 RPM torque. With tunning at 2800 RPM it increasses to 30%. The peak HP is moved from around 1200 RPM to around 1600 RPM. There is also around a 15% increase in peak HP. That kind of improvement could give an increased speed range.
Andy
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Re: Williams ws. Rankin July 06, 2006 06:46PM |
Registered: 18 years ago Posts: 1,249 |
Hello Andy,
We would have to know the cylinder size and the effective inlet valve diameter and lift on the S.E.S. engine to know how the valve was really working. Also the degrees from full open to full close. If the inlet valve is taking too long to close then at higher RPMs it is throttling. Lower BMEP and efficiency.
Also most uniflows have, of neccessity for good expansion, a very short exhaust timing generally beginning about 10 degrees before BDC and ending 10 degrees ABDC. Since the piston is eclipsing the exhaust ports for this time the effective open area of the exhaust ports is getting squezzed pretty tightly. Round ports of course more than square ones. Again limiting flow more at higher RPMs.
Thank You ---------- Bill G.
Edited 1 time(s). Last edit at 07/06/2006 06:49PM by Bill Gatlin.
We would have to know the cylinder size and the effective inlet valve diameter and lift on the S.E.S. engine to know how the valve was really working. Also the degrees from full open to full close. If the inlet valve is taking too long to close then at higher RPMs it is throttling. Lower BMEP and efficiency.
Also most uniflows have, of neccessity for good expansion, a very short exhaust timing generally beginning about 10 degrees before BDC and ending 10 degrees ABDC. Since the piston is eclipsing the exhaust ports for this time the effective open area of the exhaust ports is getting squezzed pretty tightly. Round ports of course more than square ones. Again limiting flow more at higher RPMs.
Thank You ---------- Bill G.
Edited 1 time(s). Last edit at 07/06/2006 06:49PM by Bill Gatlin.
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Re: Williams ws. Rankin July 06, 2006 09:02PM |
Registered: 18 years ago Posts: 318 |
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Re: Williams ws. Rankin July 06, 2006 09:19PM |
Registered: 18 years ago Posts: 1,249 |
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Re: Williams ws. Rankin July 07, 2006 08:17PM |
Registered: 18 years ago Posts: 318 |
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Re: Williams ws. Rankin July 07, 2006 10:07PM |
Registered: 18 years ago Posts: 1,249 |
Thanks Howard,
At a 6# water rate then that is 216 HP and a little under 0.1 gallon of fuel per HP-hr.
That would be steady state though. Any idea as to how much HP you were getting?
Just wondering, if a car were using 30 HP to go down the road at 60 MPH then 3 gallons per Hr would give 20 MPG. I would expect a bit more as the boiler would be more efficient at a low firing rate.
Thanks ---------- Bill G.
At a 6# water rate then that is 216 HP and a little under 0.1 gallon of fuel per HP-hr.
That would be steady state though. Any idea as to how much HP you were getting?
Just wondering, if a car were using 30 HP to go down the road at 60 MPH then 3 gallons per Hr would give 20 MPG. I would expect a bit more as the boiler would be more efficient at a low firing rate.
Thanks ---------- Bill G.
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Re: Williams ws. Rankin July 08, 2006 08:25PM |
Registered: 18 years ago Posts: 318 |
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