Canard Community Forum  

Go Back   Canard Community Forum > Firewall Backward and Forward > Turbo or Super Charging
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #31  
Old 11-05-2005, 08:13 AM
Cozy Girrrl's Avatar
Cozy Girrrl Cozy Girrrl is offline
The MissAdventures Cont'd
 
Join Date: Apr 2004
Location: St. Louis, Missouri
Posts: 1,033
Default

WARNING WILL ROBINSON -THREAD DRIFT !!!
__________________

CG Products
www.CozyGirrrl.com - all new pages
Cozy Mk-IV RG RX Turbo
Reply With Quote
  #32  
Old 11-05-2005, 11:28 AM
MarbleTurtle's Avatar
MarbleTurtle MarbleTurtle is offline
Member
 
Join Date: Apr 2004
Location: Dalton, GA.
Posts: 1,344
Default

Actually 4 states... you forgot plasma.
__________________
Past performance is no guarantee of future results.
Reply With Quote
  #33  
Old 11-05-2005, 11:53 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
Member
 
Join Date: Dec 2004
Location: Canada
Posts: 578
Default

Cozy Girrrl has a point. Turbo compressors are designed to compress a gas- air.

If dust wants to pull 75% at 25K that's about 20 lbs./min. Divide by 2 for twin turbos is 10 each. Probably needs about 27 inches to do this at cruise rpm. Ambient pressre at 25K is 11 inches. Pressure ratio is 2.23 corrected for inlet temp, density ratio at 75% compressor efficiency is about 1.7. Each compressor has to have an inlet flow of 17 lbs./min.

Twin T3s with 50 trim, stage 3 turbine wheels .63 A/R housings, integral wastegates would give a good surge margin up here and not be half bad at lower altitudes

Just my 2 cents.
Reply With Quote
  #34  
Old 11-06-2005, 09:53 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

Quote:
Originally Posted by no4
BLIMEY!
A couple of years ago, Dust didn't sound like he knew a carburetor from a camshaft,
How did you get to 82 " in the first place?
Cmon now No4 - give me SOME credit - i always new that a carburetor turned once for every two turns of the camshaft.

I got the 82" from burns stainless - rv got it because he knows his @#%$, simple as that.

RV - i have not reviewed the calcs yet but yours do make sense, if the engine is 100% VE - and i believe you. must be the slow rpm's that allow such bad design to be soo efficient? the 2.23 PR is allot better to deal with than the temp uncorrected and 70% VE 3.2 we came up with and the 2.8 70% VE garrett come up with.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #35  
Old 11-06-2005, 11:58 PM
mplafleur's Avatar
mplafleur mplafleur is offline
Finally at Chapter 4!
 
Join Date: Apr 2004
Location: Lathrup Village, MI (Metro Detroit)
Posts: 1,203
Default

Quote:
Originally Posted by rv6ejguy
The calculated VE for the Conti is around 100%.
I'm assuming you mean a turbo Conti.

At 25k feet, it's -30F and 11.10 inHg pressure.

100% VE at 2800 rpm give 20.6 lb/min, ideal air flow. Assuming a 1 psi vacuum draw at the inlet, a 2 psi intercooler pressure drop and 80% intercooler effeciencies. I don't know if those numbers are realistic.

Corrected to turbo map pressure and temperatures, I get a corrected suction flow of 47.8 lb/min for a pressure ratio of 2.88.
__________________
Michael LaFleur
Turbo Rotary Big EZ Retract
And no trees were harmed or killed in the creating and sending of this message. However, a large number of electrons were terribly inconvenienced...
http://banners.wunderground.com/weat...ions/76225.gif
http://banners.wunderground.com/weat...ions/76225.gif
Reply With Quote
  #36  
Old 11-07-2005, 10:42 AM
Steve parkins's Avatar
Steve parkins Steve parkins is offline
Member
 
Join Date: Apr 2004
Location: wa state
Posts: 2,163
Default

Quote:
Originally Posted by rv6ejguy
Cozy Girrrl has a point. Turbo compressors are designed to compress a gas- air.

If dust wants to pull 75% at 25K that's about 20 lbs./min. Divide by 2 for twin turbos is 10 each. Probably needs about 27 inches to do this at cruise rpm. Ambient pressre at 25K is 11 inches. Pressure ratio is 2.23 corrected for inlet temp, density ratio at 75% compressor efficiency is about 1.7. Each compressor has to have an inlet flow of 17 lbs./min.

Twin T3s with 50 trim, stage 3 turbine wheels .63 A/R housings, integral wastegates would give a good surge margin up here and not be half bad at lower altitudes

Just my 2 cents.
i read a T-4 or T6 would do the trick on the roto
if the 6 is good, could we use 2 Garnet T-3's and use longer pipe and no mufflers?
RV could you pull the stats on the roto the same as you did for the cont?
I'm still new at this(whats a Camino) so if you could,slow it down some,so i can grasp it....ie VE is very often? volume officiates ?
Reply With Quote
  #37  
Old 11-07-2005, 12:23 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
Member
 
Join Date: Dec 2004
Location: Canada
Posts: 578
Default

I've never worked through the VE thing matching turbos as this is often unknown. Sorry if this messes with your XL file.

And no, the VE for the Conti is for an atmo version, not turbo. Yes, the slow turning aspect makes up for the relatively poor port flow on these engines.

I simply use hp divided by 8.07 for mass flow.

2 psi drop through an intercooler at these low mass flows would be very high indeed unless you had a crappy or tiny core. 1 psi across the compressor face would be unlikely as well in an aircraft with a decent ram system where this loss can easily go the other way.

You are very unlikely to get more than 50-60% intercooler effectiveness in an aircraft at 25K unless you fit a massive core and duct a massive amount of air through it. Effective intercooling up here will require 50-75% of total engine cooling mass flow which is usually a huge drag producer and unacceptable.

I'm matching this for cruise, not full power at 25K where you'd probably melt it down from lack of cooling and high charge temps.

For a 200hp rotary, the numbers are essentially the same with slightly higher pressure ratios than the Conti because of the higher boost but a single turbo is more practical. The altitude you plan to operate most at is where you should match the compressor for. Are you really cruising all the time at 25K and refilling your O2 tank all the time? Surge margin at high altitude is a real problem and I don't think the T series compressors with their narrow islands are a good choice here. I'd probably suggest something like a TO4 with an E-50 compressor, P turbine wheel in a .81 or .96 housing. You are stuck with separate wastegates with a TO4 unfortunately which are heavier, more expensive, harder to plumb and more subject to vibration failures.

Again, just my 2 cents worth.
Reply With Quote
  #38  
Old 11-07-2005, 12:34 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

Yes i really am going to spend allot of time at 25,000. My normal trips will be 1600 miles to scottsdale AZ and to maryland and all over the world and country to visit all of yous on the forum.

I am a simple man. I enjoy family, friends, woodworking and plane building. To me Flyin is just a way to get to one of those items.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #39  
Old 11-07-2005, 12:41 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

As an example - i have a truck for 11 years now - 102,000 miles. That includes 5 years of 90 mile round trips once a week to plane day.

i go nowhere just to go, always have a destination that includes one of the below, just the way i like to live
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #40  
Old 11-07-2005, 01:14 PM
mplafleur's Avatar
mplafleur mplafleur is offline
Finally at Chapter 4!
 
Join Date: Apr 2004
Location: Lathrup Village, MI (Metro Detroit)
Posts: 1,203
Default

Quote:
Originally Posted by rv6ejguy
2 psi drop through an intercooler at these low mass flows would be very high indeed unless you had a crappy or tiny core. 1 psi across the compressor face would be unlikely as well in an aircraft with a decent ram system where this loss can easily go the other way.

You are very unlikely to get more than 50-60% intercooler effectiveness in an aircraft at 25K unless you fit a massive core and duct a massive amount of air through it. Effective intercooling up here will require 50-75% of total engine cooling mass flow which is usually a huge drag producer and unacceptable.
I've updated my numbers.

I used 50% intercooler effeciency, 1 psi drop across the intercooler and 0.5 psig vacuum draw at the compressor inlet.

Now at 25k altitude to get 25 inHg manifold pressure you need a PR of 2.55.

At 2800 RPM: 44.5 lb/min corrected air flow, actual air flow is 18.7 lb/min.

At 2600 RPM: 41.3 lb/min corrected air flow, actual air flow is 17.4 lb/min.

At 2400 RPM: 38.2 lb/min corrected air flow, actual air flow is 16.0 lb/min.

Manifold air temp is 145.2 deg F.

Just my 2 cents...
__________________
Michael LaFleur
Turbo Rotary Big EZ Retract
And no trees were harmed or killed in the creating and sending of this message. However, a large number of electrons were terribly inconvenienced...
http://banners.wunderground.com/weat...ions/76225.gif
http://banners.wunderground.com/weat...ions/76225.gif
Reply With Quote
  #41  
Old 11-07-2005, 01:34 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

Quote:
Originally Posted by rv6ejguy
You are very unlikely to get more than 50-60% intercooler effectiveness in an aircraft at 25K unless you fit a massive core and duct a massive amount of air through it. Effective intercooling up here will require 50-75% of total engine cooling mass flow which is usually a huge drag producer and unacceptable.
mmmmm - well if i take my naca and use it for just interlooler and combustion air - shouldn't cause that much drag, if properly designed, ima tinkin. i thought the naca was pretty effecient as long as flow through was good.

complicated to get speed - ain't it though
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #42  
Old 11-07-2005, 02:34 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
Member
 
Join Date: Dec 2004
Location: Canada
Posts: 578
Default

Quote:
Originally Posted by Dust
mmmmm - well if i take my naca and use it for just interlooler and combustion air - shouldn't cause that much drag, if properly designed, ima tinkin. i thought the naca was pretty effecient as long as flow through was good.

complicated to get speed - ain't it though
The NACA duct has poor pressure recovery but fairly low drag. The big problem is the thick intercooler core matrix has high drag. Climb at high altitudes will be the worst scenerio with high power and low mass flow available through the core. You won't believe how much airflow you need here to do the job. This is why the Reno boys use small intercoolers and ducts and LOTS of ADI. Only a slight increase in induced drag carrying say 50 gallons of water and ADI at 400 mph. ADI is obviously not viable on non-race aircraft however.

Most people underestimate the the air required to do this well. I know I did even with 20 years of turbocharging experience. My RV sprouted more and more ducts to pass more air through various heat exchangers. I see the Algie Composite aircraft being designed will use no intercooler!! I can say 100% that they will be adding one. Super efficient backward curved Indy Car compressors will not make high charge temps at altitude go away and this is a pressurized aircraft so how not to bake the passengers?

Lockheed engineers learned a lot developing the P38 intercooler systems over and over until it finally did the job properly in 1944.

Unfortunately, I blindly believed the calcs on compressor discharge temps. Due to conduction effects from the turbine section these proved to be wildly erroneous. It is not hard to see 100C/ 212F CDT climbing on a warm day at even 15,000 feet.
Reply With Quote
  #43  
Old 11-07-2005, 03:17 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

thick intercoolers - i'm gonna try to install thin ones. another reason for two intercoolers - more square footage in the wing roots. the thinner ones are more efficient. -30 going through 1" intercooler at 2 square feet should be better than -30 going through 2" at 1 sq feet.

totally agree with heat specs - plan on all negative temps to be against me and size accordingly. Nothin ever works like they "THEY" say it will and i remember you trying to isolate the compressor from the turbine heat with SS

i will probably have three sets of ducts

naca, under wing and arm pit and naca at the rear of my over sized fuel sumps - hey, thats 4 and i will augment the exhaust.

(thats the "cool" icon) heh heh heh

hopefully the fact that i am using almost no boost at sea level (1 or 2 psi/ 31.5 IM) will help me as i go up the OAT will go down and the cooling system will have cooler air to work with. It would be harder if i was boostin for power instead of just to keep power.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #44  
Old 11-07-2005, 03:21 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

Oh yeah - CDT = compressor discharge temp - could go past 300F - got to stay cool
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #45  
Old 11-07-2005, 04:27 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
Member
 
Join Date: Dec 2004
Location: Canada
Posts: 578
Default

Large face area and shallow heat exchangers are the way to go if you can wet the entire face feeding them from a small area duct and fit them in the aircraft. Hard to do both usually. We are generally stuck with small areas and deep cores. Short ducts have high losses as well. Hard to win here.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 04:43 AM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.