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When I ordered my prop from IVO I pretty much had them send me exactly what John had. He actually said..."you want what John Slade has?" At the time, IIRC , it was a 68" at the time so that is what I believe I currently have.
I too have the 2.17 redrive . I hav yet to order the module from IVO for it to regulate RPM. May do so soon.
John,
I think you and I have the same aspect ratio of 96 (?). My first start with the turbo was with a six pound spring but on advice of a trusted friend who has more experience, I replaced it with a three pound spring to start out with. It was the three pound
spring that I ran yesterday. We are thinking that minor boost should be a better starting point and reduce potential problems. Should we want more later and determine it is prudent, we can increase it. The "Performance" wastegate comes with various
springs that can be used individually or in combination from as low as 1.5 lbs upt to 25 lbs + (I believe).
The wastegate is located behind the turbo. See the attached photo. Since this shot was taken about two weeks ago, I have replaced the blue oil line with a stainless one with a 90 degree fitting. I have also fabricated and installed an additional
weight support to bear some of the load off of the turbo manifold.
I will post more pictures in separate emails so not go over size limits.
Chris Barber
From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of John Slade [jslade@canardaviation.com]
Sent: Thursday, May 27, 2010 9:40 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rotary HP revisited
Hi Kelly,
My IVO is 66 (I found 68 gave too little ground clearance), 3 blade and the higher pitch.
Yes, it's a 2.17.
Regards,
John
Kelly Troyer wrote:
John ,
What is your "IVO" diameter, number of blades and are your blades the 30 to 90 or 45 to105 degree pitch ? If I
remember correctly you have the 2.17 to 1 RD1B gearbox.................
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
From: John Slade
<jslade@canardaviation.com>
To: Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent: Thu, May 27, 2010 8:44:43 AM
Subject: [FlyRotary] Re: Rotary HP reviisted....now that I know more about it all...kinda.
Hi Ed, Chris,
That all makes sense, but I can add something from experience with the IVO prop - The minimum pitch setting seems to optimum for take-off power. When I changed from a big fixed pitch prop to an IVO at minimum pitch the difference in acceleration was very marked.
I have never taken off with the pitch at a higher setting than minimum, so I can't attest to the effect, but if you forget to put the pitch on full fine on the downwind, a go-around is much less doable.
Something else about the IVO that might help, Chris, is that when you throttle back on final the airplane will want to slow down quite quickly. This is somewhat unexpected if you're used to a fixed pitch prop that tends to make the airplane float on final.
The combination of fine pitch at idle, both rudders and the landing brake make a Cozy (or Velocity I would think) come down like an elevator.
One way to check that you have enough power would be to measure how much runway you use to reach, say, 70kts. If it's more than 2000' I'd say you're under powered. With a turbo and an IVO the acceleration should feel like a good sports car, and the increase
from 70 kts to flying speed will only take a few seconds.
My 2c.
John
to Ed Anderson wrote:
No easy answer – to all the nuances of producing power, Chris.
200 HP is a possibility depending on lots of factors (like your total induction system set up, however, I believe that 180 HP is more
in line with the likely maximum on the older 13B. The Renesis a bit more/
Fuel flow is as much an indication of power as anything short of a dyno and/or extensive aircraft performance numbers.
RPM (in my opinion) has too many variables – like I have a 74x88 prop with a 2.85:1 gearbox and can turn 6000-6200 rpm static – does
that mean I am making more or less HP than you at 6200 rpm at 35” Hg. It all depends on what prop load each of our engines are seeing at that rpm. Generally as a
rough rule of thumb you can figure 10 hp per gallon/hour of fuel flow. So it you have a fuel flow of 16 gallon/hour then your engine could be producing around 160 HP. 18 GPH = 180 HP, etc. Now your power won’t
be more than that, but it could be less. The rotary can flow considerably more fuel without making useful power than a piston engine, but it is a useful rule of thumb.
I street ported my 91 Turbo block myself using a Mazdatrix street port template. I went through 5 intake designs and several muffler
experiments before finding one that appear to give me the power I wanted. On a cold morning with OAT < 50F, I can get up to 6200 rpm and 18-20 GPH fuel flow with the 74x88 prop. So I feel I have my set up just about as good as its going to get – short of
a forced induction system.
With your prop set at max fine pitch, you have reduced the prop load on your engine to a minimum – that permits your rpm to be at a
maximum – but, that does NOT mean you are producing the power and more importantly - the
thrust needed for safe flight.
Don’t be mislead by rpm. As an extreme example to make my point,
Without a prop (almost no load) my engine will turn 5500 rpm at idle throttle setting – but I am only flowing something like 1.5 – 2 GPH which means producing something like 15-20 HP even though the rpm without
prop is higher than my static was when I had my old 68x72 with a 2.17:1 gear box. So even though the rpm is the same or slightly greater, the engine not making any where near the 150-160 HP I made with the prop on at the same rpm. Fuel flow is not a perfect
indicator but much more useful than RPM alone in estimating your power particularly with a variable pitch prop.
This is important, Chris. Years ago, there was a long EZ builder who had a non-rotary auto engine who unfortunately ended his first
flight in a fatal crash into a cactus plant. He understood the electronics just fine, but did not understand the relationship between rpm and thrust. He set his adjustable pitch prop for
maximum RPM – which mean minimum prop load, which in his case mean
minimum thrust. He managed to get airborne with this limited thrust, but could not apparently climb out of ground effect with the flight ending on impact with a cactus.
For example, you would get your highest rpm with a prop that absolutely no pitch which would produce minimum load on the engine – however,
I think you would agree there would not be much “push/Pull” by such a prop set up. With a variable pitch prop, you need to find the optimum balance between rpm and thrust. Too much rpm could indicate too little pitch (and too little thrust), too low rpm
could indicate too much pitch (and too little thrust) – neither condition gives you maximum thrust.
The only way I can think of to find that optimum balance between rpm and thrust is to attach your airframe through a scale to an anchor.
Then measure the pull on the scale at various rpm and prop pitch settings. This should help you find where combination of engine rpm and prop pitch provides maximum thrust (at least maximum static thrust – which is a good start). Perhaps someone else can
offer a better and easier method. Yes, you should be able to get a feel during taxi test – although some folks frown on the idea of high-speed taxi test. Theoretically you could use an accelerometer, some accurate speed measurements the weight of your aircraft
and calculate the effective HP – that has been done with automobiles.
In cases were folks are using fixed pitch props with parameters similar to those used by others, you can make a comparison and get
a rough feel for engine performance based on RPM. Unfortunately, with a variable pitch prop making such comparisons is more difficult and questionable. Now if you can find someone using the same variable pitch prop you are using and compare your rpm and
prop settings, that is certainly something worth checking into.
Just continue to ask these kinds of questions and to think about the issues in producing power and thrust – you’ll be ready.
Ed
.
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Chris Barber
Sent: Wednesday, May 26, 2010 9:51 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Rotary HP reviisted....now that I know more about it all...kinda.
I know this must have been discussed, but perhaps more in passing or in some of Tracy 's literature (now kinda dated, especially
with some of the strides he continues to make), but what is the conventional wisdom as to rotary horsepower? I know when I first started looking into it, oh many years ago, it seemed the impression I got was that you could pretty easily achieve 200 hp, however,
that is now a bit lower. Some of the tricks to get the higher HP was mild and medium porting, bridge, "J" and "P" porting. Then there was the option of turbo...the one, in combination with a medium street port, I chose.
When started today, mine was turning about 6200 rpm at 35 MP (with a 3 lb spring in the wastegate).....it surged forward against
the chocks and breaks. IVO prop full fine. Nice feel of power even if it likes to heat up fast in 90 degree weather like this.
Also, I think this was discussed before too, when I go WOT my engine develops up to about 6250 rpm, but then drops a couple/few
hundred rpm to usually just under 6000....sometimes just above. Thoughts? Ed, (perhaps Al)it seems you may have chimed in before. Regrettably, when I search the archives I tend to get frustrated due to thread drift.
I heard a lot about porting when I was initially investigating all this and I chose to use a medium street port. I let Mazdatrix
do the work. That being said, I have read all but nothing on others porting their engines (other than a LOT from PL on P ports). Since standard porting does not reportedly effect reliability, only, potentially low low idle (I can idle as low as about 1300
rpm when warm smoothly) why is it not discussed and/or utilized more?
Just curious guys/gals. Discuss <g>
Always loved the lines of a Tailwind – in fact, I have the plans and license to build a W-10 sitting on my book shelf. Unfortunately,
I doubt I’ll ever get around to it.
Ok with thermostat in the system holding it at 190F – we really won’t know how much reserve capacity you have in your cooling system
until the power goes up.
I agree with George, 200HP out of an N/A 13B is really pushing it. I think 180HP is a more realistic expectation – but, hey you never
know. It amazing how power goes up when things come together.
Enjoy and fly safe.
From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of John
Sent: Wednesday, May 26, 2010 2:36 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Emailing: 3 view w-10 003, first flight
My most humble thank you to flyrotary and all you fine folks that have helped bring my project to flight. Ed and many others whom
I won't try to name here because I would miss many. The plane is a Wittman Tailwind W-10, empty wt. is 981 and it is a tri-gear, Wt. is within 6 #'s of similar trikes w/ 0-320 engines. I have the thermostat in the engine because most of the year it is not
very hot, if we get 50 days with the temperature over 70, we have had a hot summer, not a lot of beach bunny activity. 7-1 I'll be 74 and have realized my dream, now it's all gravy. Again, thanks guys!! JohnD
Your message is ready to be sent with the following file or link attachments:
3 view w-10 003
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