It's suprising a 2 stroke engine didn't enter service. Rolls-Royce did have to 2 stroke sleeve valve crecy in development but this would have been much easier if well understood poppet valves were used instead. With the poppets being intake types there would be no cooling issue. The challenge with these engines is getting a mixture near the spark plug suitable for ignition; a prechamber is the usual solution.
WI The Rolls Royce Vulture is a success
- Thread starter fastmongrel
- Start date
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wuzak
Captain
A lot of 2 strokes don't have valves at all. Most motorcycle 2 strokes, for instance, had the air-fuel mixture enter the crankcase before getting transferred to the combustion chamber via a transfer port. The piston performed the function of valves.
For the Crecy the air was pumped directly into the cylinder, excess air being used to scavenge the exhaust gases. Fuel was directly injected into the top of the cylinder, with the chamber shape specifically designed to give a stratified charge allowing for a weak mixture but rich in the location of the spark plugs.
Sleeve valves worked wel in the Crecy. The main issue was piston cooling, as at the same rpm there was half as much time between combustion events as on a conventional engine.
I think valved 2 strokes are common in the heavy diesel market, ensures better scavenging. Of course Ralph Sarich's Orbital engine company developed a succesfull 2 stroke with an adjustable side port. The engine while technically successfull and very clean had found only a few markets eg marine outbouards where 4 stroke can be a pain to maintain. The compressed air fuel injection system has been very succesfull however due to its abillity create a stratified charge which is important to ignite two stroke mixtures. Modern electronics and sensors make getting a good mixture much easier. Two stroke is still a good idea if done in a sophisticated way. Crecy might have found a market but for the gas turbine.
johnbr
2nd Lieutenant
- Thread starter
- #85
fastmongrel
1st Sergeant
Doesnt matter if its not a Vulture its still a cracking photo. Nice find johnbr.
johnbr
2nd Lieutenant
Thanks
wuzak
Captain
Found another potential recipient for a successful Vulture.
http://www.aviastar.org/pictures/usa/mcdonnel_xp-67.gif
If my scaling is correct the Vulture should fit up to the XP-67's firewall, but it would be tight.
Now, when fitted to the XP-67 (and XP-49) the Continental IV-1430s made an estimated 1050hp, compared to the 1600hp they were supposed to make.
From memory the XP-67 maximum speed was 405mph. If it got the full 1600hp from the IV-1430s (something the V-1710 would have been more than capable of at the time) the max speed would have been pushed out beyond 450-460mph.
A successful Vulture would have easily been capable of 2000hp (it was in 1941), which would give the XP-67 an estimated top speed of around 500mph. By 1943/44 when the XP-67 was testing the Vulture probably would have been cleared for 2500hp. That would mean a top speed of over 500mph.
Of course the Vulture is substantially heavier than either the IV-1430 or the V-1710, which would result in speeds less than those estimated.
http://www.aviastar.org/pictures/usa/mcdonnel_xp-67.gif
If my scaling is correct the Vulture should fit up to the XP-67's firewall, but it would be tight.
Now, when fitted to the XP-67 (and XP-49) the Continental IV-1430s made an estimated 1050hp, compared to the 1600hp they were supposed to make.
From memory the XP-67 maximum speed was 405mph. If it got the full 1600hp from the IV-1430s (something the V-1710 would have been more than capable of at the time) the max speed would have been pushed out beyond 450-460mph.
A successful Vulture would have easily been capable of 2000hp (it was in 1941), which would give the XP-67 an estimated top speed of around 500mph. By 1943/44 when the XP-67 was testing the Vulture probably would have been cleared for 2500hp. That would mean a top speed of over 500mph.
Of course the Vulture is substantially heavier than either the IV-1430 or the V-1710, which would result in speeds less than those estimated.
wuzak
Captain
Just looking at some pictures of the R-4360 when I came upon this:
http://www.enginehistory.org/P&W/R-4360/Image61.jpg
The interesting part for me is the master rod in the upper left of the pucture with the pins for the slave rods next to it. Note the holes in the pins allowing the rod cap bolts to pass through.
One wonders if Rolls-Royce considered doing this for the Vulture. One of the failures was the cap bolts being necessarily shorter, not allowing Rolls-Royce to get the amount of pre-tension on the bolts that they would otherwise aim for.
http://www.enginehistory.org/P&W/R-4360/Image61.jpg
The interesting part for me is the master rod in the upper left of the pucture with the pins for the slave rods next to it. Note the holes in the pins allowing the rod cap bolts to pass through.
One wonders if Rolls-Royce considered doing this for the Vulture. One of the failures was the cap bolts being necessarily shorter, not allowing Rolls-Royce to get the amount of pre-tension on the bolts that they would otherwise aim for.
johnbr
2nd Lieutenant
Found this
wuzak
Captain
Hi John,
Nice cutaway.
It is, of course, by Lyndon Jones.
Nice cutaway.
It is, of course, by Lyndon Jones.
johnbr
2nd Lieutenant
He dos very good work.
wuzak
Captain
Yes he does.
Do you have his book of cutaways? It is recommended.
On the Vulture, it is quite a compact form. Future versions would have lost, maybe, 200lbs by going to an epicyclic reduction gear. It would also have greatly benefitted from Rolls-Royce's supercharger development at around the time it was cancelled. Pity they could not continue with it.
Do you have his book of cutaways? It is recommended.
On the Vulture, it is quite a compact form. Future versions would have lost, maybe, 200lbs by going to an epicyclic reduction gear. It would also have greatly benefitted from Rolls-Royce's supercharger development at around the time it was cancelled. Pity they could not continue with it.
Mr Wuzak, this is my first post so apologies for the debut post being of a begging nature, but you wouldn't happen to still have those installation drawings readily available would you? I could contact RR at Derby but I was hoping you might still have them knocking about and might save me the trouble!
Many thanks
Matt
wuzak
Captain
- Thread starter
- #96
fastmongrel
1st Sergeant
This makes me realise I need to find the pile of scribbled notes and make a start on my what if timeline for the Washington MkI with Vultures
wuzak
Captain
No, I don't at the moment.
I can scan it at work on Monday. They have a bigger (A3) scaner there.
wuzak
Captain
Hope this works.
Scanned files of the Vulture installation.
Scanned files of the Vulture installation.
