|
George,
The "Turbonetic" website says that the turbine housing A/R ratio can only
be guesstimated based on displacement, rpm, etc............To come up with the
optimum ratio for a given installation requires real world testing...........Lucky
for us several of this forum are flying turbos with varying sucess so we can
use their sucess and failures as a guide for our own installations..........
I am with you as to the higher ratios (Looser)(.96 , 1.15 , 1.32) at least for
the TO4-E (which is what I am interested in) are probably ballpark ratios
for our 13B use based on their use by several of the group...........I intend to
fly at the approximate altitude John Slade uses (about 12,000 ft) and am
interested in normalizing at altitude so do not need huge amounts of power
so the looser housing (1.15, 1.32) will probably be what I will purchase......
I have a used TO4 with a 1.32 A/R housing so will probably purchase a
TO4-E , 50 , P trim , Big Shaft , Water Cooled , 1.15 Tangential Housing
like the "Cosy Girrrls" to avoid any chance of overspeed at the altitudes that
I plan on flying..............
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Original message from "George Lendich" <lendich@aanet.com.au>: --------------
Kelly,
How do they calculate those AR figures. My notes say that the AR is better for our application from 1.15 to 1.3.
George ( down under)
John and All,
I am also looking seriously at the "Turbonetics" TO4E..............Can you clear
up something for me............The post below seems to indicate that the "Cosy Girrls"
have a .96 A/R turbine housing but from previous posts I thought they had a 1.15 A/R
housing for more boost at higher altitude............Also curious if your turbine housing
is split (two openings) or one opening ?.............You say that on takeoff you are at
about half throttle to stay at 42" mp.............Can you tell me how much throttle you
need at 12,000 ft to maintain 42" MP ?...................
Thanks,
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Original message from John Slade <jslade@canardaviation.com>: --------------
Hi Chris,
I can provide one piece of second hand information and a lot of sympathy....
With regard to the ceramic bearings, I was told that the extra expense wasn't necessary, and that the 'big shaft' had been proved to hold up on an aircraft, while no-one (he or I knew) had yet flown ceramic bearings.
On the sympathy side - I can relate to your agony here. After blowing two stock turbos and one modified hybrid (one of which was at 11,000' and took out my apex seals) I was, shall we say, under a little more pressure to get the decision right this time.
After studying turbo maps and specs and reading everything I could find, I eventually took the same logic on the turbo choice that I did on the engine rebuild and on aluminum welding - "this is something you learn to be an expert in over many years, not months. I do not have the time or tenacity to become a true expert in this field, and I don't wish to employ the skills of an amateur (me) .... so I need to use the skills of someone who IS a true expert." Next problem - how do you know who is a true expert and who is just claiming to be one?
I came across a turbo guy on the http://canardaviation.com forum (the initial communications should be in the archive) who was flying a turbo powered Subaru and seemed like a true expert. I think he's in Canada. He'd been "into turbos" all his life and certainly sounded like he knew what he was talking about. I gave him all my specs in terms of engine, planned flight regime and usage, and he came back with the list of goodies I now have. As with all critical recommendations, I checked with others whose knowledge I'd gained a healthy respect for. The Cozy Girrrls had independently arrived at almost exactly the same choices, except that they wanted more power at higher altitudes than me, so they choose the 9.6 aspect ratio which would provide less on take-off, but more over 18,000'. I had specified a max cruise altitude of 15,000'. Greg Richter also used a Turbonetics, but without an auto wastegate. Leon in Aussie (another true expert who used to contribute heavily to this list) agreed that the specs and manufacturers were appropriate. At that point I put all the agony behind me and purchased EXACTLY what I was told would work. Thankfully (once I put the suction on the correct side of the wastegate :) it did work and I've had no further turbo issues. The push in your back on take-off feels like a Porche. I do the take-off based on the manifold pressure keeping it below about 42 which equates to just over half throttle. I think the late great Paul Conner said it best after flying in Dan Crugar's 0360 powered Cozy IV, then taking mine for a high speed taxi test. "Wooooo!"
You, of course, have an advantage over me - You can follow and examine my installation. The cost of a commercial flight into West Palm (or Albany after early May) would be minor compared to the value gained. You'd be welcome any time.
Regards,
John
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
|