Airflow Performance FI Pump Drive

>> >>> > How was the Airflow Performance FI fuel pump driven when installed
>> on
>> >>> > the rotary? I think it's gear driven on a LyCont..
>> >>> >
>> >>> > Side question: Did the the FI use one orifice (injector) per rotor
>> >>> or two?
>> >>> >
>> >>> > Another side question: Where did the FI measure the equivalent of
>> >>> deck
>> >>> > pressure (manifold pressure) when mounted on the rotary? I was
>> >>> thinking
>> >>> > the engine it was installed on was P-Port with a slide throttle.
>> Were
>> >>> > there any particularly difficult challenges with metering accuracy
>> >>> when
>> >>> > at high power settings?
>> >>> >
>> >>> >
>> >>> > Regards,
>> >>> >
>> >>> > Matt-
>> >
>> >>> I think Steve BeckHam can answer those questions as the early Power
>> >>> Sport engines
>> >>> use Airflow Performance fuel injectors.
>> >>> --
>> >>> Paul Lamar ...No rotor no motor.
>> >>
>> >> Thanks Paul.. I couldn't remember who said they had been using the
>> >> Airflow Performance.. Yes, Steve Beckham.
>> >>
>> >>
>> >> Matt-
>> >>
>> >> Also many racing engines used mechanical fuel injection.
>> >> Here is a picture. Also a rather grainy picture of the PS engine.
>> >>
>> >> BTW guys please look at all the Youtube videos and click on the fifth
>> >> star over where it says ratings. A good search phrase is RX7
>> Airplane.
>> >> That gets you to the right place. Than click on More From: UTUBPLEASE
>> >> That will show you all 18 rotaryeng.net videos.
>> >>
>> >> We need to promote RX8 sales as Mazda needs to keep making rotary
>> engines
>> >> until some other major manufacturer wises up and starts making turbo
>> >> compound rotaries for street cars. I suspect Mazda management lacks
>> >> a bit of vision on this subject or they would have done it years ago.
>> >>
>> >> The piston engine guys are going to have a heck of a time with
>> >> turbo compound as half the heat and kinetic energy goes towards
>> >> destroying the exhaust valve. The exhaust valve was the Achilles
>> heel
>> >> of the CW R3350TC. CW spent most of the development money dealing
>> with
>> >> that problem.
>> >>
>> >> Also keep an eye on Popular Science or Pop Mechanics.
>> >> Reputedly there will be an article by Don Sherman on the
>> >> turbo compound truck engines shortly. Send email to the mag
>> >> and tell them how much you enjoyed the turbo compound article
>> >> whether he does a good job or not :)
>> >>
>> > > Paul Lamar
>> >
>> > paul,
>> > my experience, and referral to Don Rivera's manual, indicate Airflow
>> > Perf generally uses electric FI pumps on LyCont. I have both a cam
>> > driven mech pump and an electric Boost Pump on my Lyc 0-360 w/ FM200.
>> > Ck his website
>> >
>> > steve wolpin
>> >
>> >
>> > Thanks Steve.
>> >
>> > Paul
>>
>> Matt: Paul was correct.
>> On all the Powersport prototype rotary engines from 1990-1998, we used
>> Don
>> Rivera's fuel controller/servo on all the later Superlight prototype
>> engines and the last version which was the Mazda conversion engine. You
>> asked about fuel pumps and other.
>>
>> Hope the following notes help. Don's
>> AirFlow Performance unit is a refinement of the Bendix constant flow,
>> mechanical fuel injection system used on certified engines. Don worked
>> for
>> Bendix and all those experiences served him well. Don's units work with
>> either engine driven pumps (ie. standard Lycoming practice) or dual
>> electric
>> pumps, which is what we used on the rotary engines. The signal for
>> Don's
>> Airflow Performance units use a highly effective venturi. This venturi
>> creates the signal for the fuel controller/servo....the more airflow,
>> the
>> more pressure differential and that alters the mixture accordingly.
>>
>> His
>> unit also provides manual mixture control to refine the mixture based
>> on
>> altitude,EGTs, etc. On Don's standard Lycoming units, his castings
>> include everything in one nice casting. For our rotary engines, we
>> sought to
>> package the system as tightly and simply as possible so Don provided us
>> a
>> "detached" controller/servo and we made our own venturi. This allowed
>> us to
>> mount the servo right next to the housings and in line with the throttle
>> arms coming out of the rotor housings.
>>
>>
>> Our engines had the throttle plates
>> located in the rotor housing peripheral ports. So we used an
>> interconnect
>> between the two throttle plates and another heim jointed arm connected
>> directly to the servo controller. Detaching the fuel controller/servo
>> allowed us to put the venturi in the inlet of the plenum chamber. We
>> also
>> use AirFlow Performance dual electric pump package and all other
>> necessary
>> goodies such as relief valves, etc. It is all good stuff.
>>
>> We had used many of Don's Airflow Performance units on Lycoming engines
>> we
>> built for customers during those years and Don's equipment performed
>> flawlessly. And they worked without a hitch on all our rotaries as
>> well.
>> When we were using direct injection with injectors screwed directly in
>> the
>> trochoids, we used vented nozzles.
>>
>> When injectors were used in the ram
>> tubes we used unvented nozzles. I have detailed photographs of these
>> installations in the RV-3 and RV-4 if it would be helpful for you to
>> better
>> understand how this all went together. When it comes to mechanical fuel
>> injection systems, Don and his people are great resources and a delight
>> to
>> work with.
>>
>> Steve Beckham
>
>
> Thanks Steve..
>
> I think your implementation is the way to go. I might be tempted to
> try a mechanical pump, but I can see going either way on that one. If
> people went down this path they would spend a bit more money up front,
> but I think the end result would be more successful rotary engine
> installations and maybe less money spent in the end.
>
>
> Regards,
>
> Matt-
>
> How far lean of peak did you lean your engines Steve?
> --
> Paul Lamar ...No rotor no motor.

Matt--we did first try a mechanical fuel injection pump on the first
SuperLight engine, with the pump driven by a gilmer (cog) belt. All
subsequent engines used dual electric pumps. There is an worthy sub-note
regarding our experience with the engine belt-driven fuel injection pumps.

When we started running the first engine (a dual side port with aluminum
housings) we started immediately having torsional issues. When we would run
the engine and planetary reduction gear on the water brake dyno, at certain
rpm, under certain conditions, the belt would blur and jump teeth. This was
prior to shearing the engine/dyno spline. Bigger shaft/spline and same
thing happened again.

These torsional issues were later resolved with
pendulous dampers on eccentric shaft when using planetary reduction drives
and then to torsionally stiff internal spur gear reduction gear finally to
eliminate the neeed for the pendulous dampers. But first indication of
torsional issues was the belt drive blurring on Hilborn fuel injection pump
at certain rpm.

Paul--as to your question on running lean of peak.
In flight testing we generally operated the engine lean of peak at cruise
power.

On the first SuperLight prototype, we made a continuous flow, fuel
injection system with direction injection nozzles (deflecting off the rotors
in an attempt to get better vaporization and some hopeful stratafication).
This allowed us to run the engine the leanest of any engines we made. A
part of this was probably due to placement of injectors and other issues.
We experimented with a myriad of nozzle positions and we can go over the
pictures if you want.

I earlier saw some of my knee-board flight logs on
this early engine but can't locate them now. Will keep looking. What I do
remember most about this system was the configuration produced the very
leanest possible mixtures to an almost goofy level. Below 5500 rpm you could
lean it to where it simply started to lose power by putting the fire out....
in the low 1300 EGT degree range with no ragged misfire.

For comparison,
EGTs on the dyno at best power were as follows--1480 EGT @4,000 rpm/ 110hp;
1500-1525egt@ 4500/135hp; 1600 egt @ 5000 rpm/160 hp; 1620-1650 @ 5500/180
hp; 1620-1690@ 6,000/180 hp. With this system and the jetting the notes
show we were a little rich at the higher rpms on these dyno runs.

A part
of the cruise anomaly may have been related to the fact that back then our
cruise rpm was very conservative because this thing was fresh off the paper
and we were very incremental in raising sustained three and a half hour
flight legs. In those early development phases we were generally cruising
in the low 5,000 range. We were running an 84" prop.

The later engines and systems could not be leaned as aggressively without a
substantive misfire. On the last conversion Mazda engine, WOT @ 7,000 rpm at
2500 ft/OAT 65F at best power produced EGTs of 1700 front and 1650 rear
using rotor direct injection. This was 235-239 mph in the RV-3. In the
same aircraft, notes show 6500 alltitude @ 5900rpm leaned to best power
1500 front and 1600 rear. Some dyno numbers for the SuperLight engine
installed in the aircraft @ 5500 rpm was 1650-1700 leaned to max power and
1500-1600 full rich.

At cruise, a flight log entry at the same engine at
5,000 rpm max lean was 1400 EGT (OAT 45F). On the dyno in the last
SuperLight engine recorded 1410 and 1430 EGT at 5200 EGT full rich. But the
dyno numbers in isolation do not mean much. We were simply changing so many
variables at the time. All data logging back then was manual. All the
above numbers were with the AirFlow Performance fuel controller and our
homemade venturi for the signal.

In the fall of 1995 I flew the RV-4 with the Mazda conversion engine to
Montana on a business trip and have the following numbers: lean of peak
5,000 rpm @7500 ft , EGT 1500&1550; 5200 rpm 1500/1600. Final leg of that
return flight Nampa to Hatch International @5600 rpm, 10,000 msl EGT's were
also 1500 and 1600.

But an important footnote to these numbers was the
engine had to be operated with a retarded throttle to prevent misfire
regardless of rich/lean. We earlier had moved the nozzles in the rotor
housings (various locations) during this period in an attempt to address
this issue. We were consitantly plauged with a misfire on takeoff and
cruise at WOT which could be cured only by retarding the throttle. This
would occur from sea level to over 10,000 ft. Alan's flight notes show the
same thing.

Finally we stumbled on a cure. In desperation, we moved the
fuel injection nozzles from the direct injection location in the rotor
housings to the induction tubes right at the base of where the induction
tubes entered the periperal port, just outboard of the throttle plates in
the housings. We had brazed these ports into the tubes earlier to provide
supplemental nitrous fuel nozzles. This completely fixed the WOT misfire.

Unforturnately we didn't have time to get good data in this location as
Everett was killed shortly thereafter. Our subjective analysis was that the
engine made more power with a higher fuel burn. But that is probably skewed
by the fact that we were testing an in-flight adjustable propeller that was
allowing us to develop full power at takeoff and WOT operation at cruise.
So no good data set in that configuration.

We are using the exact same
constant flow/nozzle configuration on the engine we are now building for the
new RV-3. We are using the same configuration nozzles/sizes with nozzles in
the induction tubes, Airflow Performance fuel controller and our venturi in
the plenum inlet. This is exactly as configured in the engine in the RV-4
at the time of the crash. We are hopefull this will give us some good
numbers in the future from both the dyno and in flight tests for the folks
who have interest in this type of lower tech old school system.

We
assembled the power section of the engine this past week. As a test
baseline, we built the engine with the smaller ports that we used in the
SuperLight engines because we never used the larger ports and throttles on
these engines and they always had the best fuel burns with the direct fuel
injection in the trochoids. So we want to get some good dyno numbers with
the smaller ports and with the nozzle in the base of the runner. But to go
fast we probably will end up taking it apart and installing the larger
ports/throttles after hopefully getting some good dyno data in this
configuration. Based on the earlier work we did with the smaller ports and
throttle plates, power will probably peak in 5500-5700 rpm range.

Steve Beckham

Fantastic information. Thanks for sharing it.

Regards,

Matt-

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