Engine technology free-for-all

[Pierce89]

Lets get real, a twostroke engine would have to be first choice. POWER to WEIGHT can't be beat. New developments now have reed induction engines making as much as rotary valve engines. New cylinder porting layouts ( also new developments ) will be pushing 125cc engines in the region of 60HP ( natural aspiration ) this in anyones terms is fantastic. More power than a 450 fourstroke MX bike and one hell of a lot cheaper to run.

60hp is indeed more than a stock 450 four stroke, but I weigh 6'2" and 240 pounds and a 450 4t will help me to lap seconds a lap faster than I would on a 60 hp 125. Hell, in a 60 hp 125, the power valve wouldn't open till somwhere close to 13,000 rpm(probably). It would have a terrible powerband for American motocross with jumps right out of the turns etc. Maybe, it would be good for road racing... But, motocross would not be an ideal place for that engine IMHO, but then again I'm no Ryan Villopoto.

[J.A.W.]

60hp is about what the old CR/KX 500s were also making, from a dead basic 2T design,
& giving a real hard (but short) torque hit, not real rider friendly, but great fun in the dunes..

Fat lazy 450 4Ts are by comparison, too easy to ride, just as Moto GP bikes are - but do cost a bundle..

A modern update of a KTM 380 2T might be 'bout right, IMO, with enough cubes to be able to tune it
for a wide/progressive power-band, & still light 'n' snappy/revvy yet controllable - when you really want to get it on..

Interestingly, although Honda don't/wont sell 2Ts anymore, they still support their existing 2T machines,
parts-wise - so these guys still build & sell them, if you want a 'new' one..

http://www.servicehonda.com/component/c ... e-4-stroke

[riff_raff]

How about an electric/turbine hybrid VTOL multi roll supersonic combat aircraft.
I could build you one of those.

If you browse through some of the recent patent applications from P&W, you'll find some examples where they propose using a recip 2T CI engine fed by a turbofan and coupled to a generator to produce auxiliary electrical power during extended cruise flight.

[autogyro]

How about an electric/turbine hybrid VTOL multi roll supersonic combat aircraft.
I could build you one of those.

If you browse through some of the recent patent applications from P&W, you'll find some examples where they propose using a recip 2T CI engine fed by a turbofan and coupled to a generator to produce auxiliary electrical power during extended cruise flight.

Yes I have seen some of them.
That might help stop Boeings from catching fire on the ground but it is not what I had in mind.

[Brian Coat]

autogyro wrote:
"How about an electric/turbine hybrid VTOL multi roll supersonic combat aircraft.
I could build you one of those."

Nice one.

But a very efficient electric gas turbine at F1 power, weight, Mach number and altitude requirements?

This may even be beyond the build capabilities of you and your shed, Autogyro!

[autogyro]

autogyro wrote:
"How about an electric/turbine hybrid VTOL multi roll supersonic combat aircraft.
I could build you one of those."

Nice one.

But a very efficient electric gas turbine at F1 power, weight, Mach number and altitude requirements?

This may even be beyond the build capabilities of you and your shed, Autogyro!

Oh I dont know Brian, Lockheed cannot make one work so I should be able to do at least as well as them.

[Pierce89]

60hp is about what the old CR/KX 500s were also making, from a dead basic 2T design,
& giving a real hard (but short) torque hit, not real rider friendly, but great fun in the dunes..

Fat lazy 450 4Ts are by comparison, too easy to ride, just as Moto GP bikes are - but do cost a bundle..

A modern update of a KTM 380 2T might be 'bout right, IMO, with enough cubes to be able to tune it
for a wide/progressive power-band, & still light 'n' snappy/revvy yet controllable - when you really want to get it on..

Interestingly, although Honda don't/wont sell 2Ts anymore, they still support their existing 2T machines,
parts-wise - so these guys still build & sell them, if you want a 'new' one..

http://www.servicehonda.com/component/c ... e-4-stroke

Actually Honda has a lot of brand new 2006- 2008 250 2t still out there for sale because the cr250 sold so poorly after the 450 came out. I know my local Honda dealership still has 2 brand new cr250's from that period and my buddy who works there, said all the dealers around our area still have some.
Edit: regardless of what my tablet thinks, the digits above are not a phone number.

[J.A.W.]

Really?
8-9 year old 'new' bikes still awaiting buyers - still sitting unsold in a Honda showroom, seems doubtful/unlikely..
If you'd kindly take a pic, & post it as evidence..

There sure aint any around here - for a 2T, you have to go to Yamaha or a Euro dealership ( KTM/Gas-Gas & etc)..

It is certainly true that Honda makes more profit for its dealers selling the plentiful ( & expensive) parts & service
required by their 4T machines, ( its bad for dad & kid budgets, though)..

[J.A.W.]

P & W attempted a version of the H-24 sleeve-valve piston aero-engine,
- but like R-R, couldn't match the Napier (Halford designed) Sabre..

http://www.enginehistory.org/Convention ... WLC3_1.pdf

[J.A.W.]

Document tabulating WW2 American aero-engine serviceability.. http://www.usaaf.net/digest/t115.htm

http://i.imgur.com/nhg0YMT.jpg

MONTHLY MAINTENANCE MAN HOURS PER ENGINE IN USD FROM JULY 1943 TO AUGUST 1945

& per T-C's recent interest in sleeve valve engine merits*, I found this Bristol TBO in a period 'Flight' article..
https://www.flightglobal.com/pdfarchive ... 01350.html

* The linked forum thread which included a Kiwi Bristol Hercules connection rang a personal bell..


( & where the splendid TBO's obtained by proper flight handling/maintenance in NZ, was duly noted)

..as a kid I recall the RNZAF Hercules-powered aircraft flying from the local military aerodrome,
& that they were markedly quieter than the US radial powered aircraft such as the Douglas machines..

The RNZAF used Bristol Hercules powered H-P Hastings' too, & ironically enough,they were replaced by
the Lockheed Hercules as transport aircraft - & yet even more ironically - the RNZAF sent their Hercules..
..powered Bristol Freighters to the ' Nam (to the incredulous amazement of US forces), rather than risk..
.. their expensive new C-130s in dicey supply runs, as the USAF were fairly profligately doing..

..meanwhile.. the USAF were flying Lockheed's next gen Starlifter to Antarctica, transiting via NZ..
&

[J.A.W.]

For T-C, another 'Flight' article with a Bristol Centaurus focus..
& which considers the issue of TBO, inc' regulatory vs actual mechanical durability/wear factors.

http://www.flightglobal.com/pdfarchive/ ... 03077.html

& below, a period ad, listing the sporting/world speed record merits - of an earlier DOHC/4V mill..

http://www.flightglobal.com/pdfarchive/ ... 01671.html

[Tommy Cookers]

thanks - but can't get flightglobal with this present PC as its browser is now too old

lately I was looking at forum posts etc relating to the great lean-running (of aircraft engines) controversy that's been going for years
these engines often have uneven charge distribution so the manufacturers now restrict the leaning (by EGT) ....
much more than they did 50 years ago in the same engines
some aftermarket hardware producers and their customers reject these restrictions

and preservationists now find that eg the radials were similar in this respect
eg 'Auto Lean' in at some engines that made history was actually somewhat rich

http://www.gami.com/articles/bttfpart1.php
http://www.gami.com/articles/bttfpart2.php
http://www.gami.com/articles/bttfpart3.php
http://www.planeandpilotmag.com/article ... anagement/
http://www.enginehistory.org/phpbb/viewtopic.php?t=190

[J.A.W.]

thanks - but can't get flightglobal with this present PC as its browser is now too old

lately I was looking at forum posts etc relating to the great lean-running (of aircraft engines) controversy that's been going for years
these engines often have uneven charge distribution so the manufacturers now restrict the leaning (by EGT) ....
much more than they did 50 years ago in the same engines
some aftermarket hardware producers and their customers reject these restrictions

and preservationists now find that eg the radials were similar in this respect
eg 'Auto Lean' in at some engines that made history was actually somewhat rich

http://www.gami.com/articles/bttfpart1.php
http://www.gami.com/articles/bttfpart2.php
http://www.gami.com/articles/bttfpart3.php
http://www.planeandpilotmag.com/article ... anagement/
http://www.enginehistory.org/phpbb/viewtopic.php?t=190

T-C, its too bad that you cannot read the "...reference material that I linked."
As BMW found & Bristol belatedly confirmed, radial engines - with their inherently problematic mixture distribution, did gain significant benefit from direct injection.

& Bristol had found that sleeve-valve merits included ( as Ricardo predicted) certain flow dynamics,
which enabled aspects of improved port injection performance, too..

[J.A.W.]

If of interest, find below a table, listing British aero-engine data - from 'Flight' - 70 years ago.

http://www.flightglobal.com/pdfarchive/ ... 01491.html

[Tommy Cookers]

[quote=J.A.W.].......As BMW found & Bristol belatedly confirmed, radial engines - with their inherently problematic mixture distribution, did gain significant benefit from direct injection.
& Bristol had found that sleeve-valve merits included ( as Ricardo predicted) certain flow dynamics,
which enabled aspects of improved port injection performance, too..[/quote]

charge distribution problems can be worse with DI or PI than with carburation or similar at the throttle body
(for the best current appreciation of the practicalities the appropriate forums can be googled)

DI helps in low boost engines by enabling the raising of CR .....
it loses in high boost engines the large saving in supercharger work etc of fuel-evaporation cooling