Monkworkz Introducing the MZ-30L

Greetings,

In reference to the front page on Friday Aug 20, 2021.

Device name: MZ-30L.
Description: 3 lb, 30 amp, vacuum pad driven generator for experimental aircraft running Lycoming engines.
Company: Monkworkz.
Price: $995.

Installation manual and frequently asked questions are on the website: monkworkz.com.

A bit of commentary:
The manual is long and detailed because this device is different than anything else for this application.

It does everything I need in a single power source. I can run solely on this power source from start up to shutdown and I'm at a towered field where long taxis and ground delays are common.

I have an IFR RV-8 with dual electronic ignition and I wanted a backup power source that wasn't difficult to install, powerful enough to carry all of my typical loads, and light enough to offer a substantial weight savings over a single alternator/dual battery PC625 setup. This device checks all of those boxes for me. Onboard fuse and current shunt are bonuses on top of that.

RPM vs power output:
The manual objectively addresses this: ~900-1000 is where you will get 15 amps. But subjectively, even at 700-800 RPM I still get enough power for my plane but not 15 amps and there are periods when I'm slowing down that the battery is carrying my system. From the Sacramento Sky Ranch Manual, 2nd edition, on idle speed, pg 137: "An Idle Speed of 1100 is necessary with cold oil to create sufficient splash." Given that, 900 RPM shouldn't be a problem for anyone but you know your own airplane. For me, even doing just a lap or two around the pattern I come back with a charged battery after tower delays, and long taxis out and back.

Cooling:
It does require one more cooling duct than a traditional alternator (per Vans instructions). The cooling duct provided is identical to Vans duct material for an alternator. The duct inner diameter is 0.65", that is around 1/3 of a square inch in area. Estimating what sort of loss of cooling is difficult. How much area do all the passageways between the pressure side and exit side of the cowling add up to? For rough comparisons the inlet area of my cowling is around 64 square inches (two inlets, ~4 inches high x ~8 inches wide), so we're talking about adding something that is less than 1% of the inlet area. My engine temps are well managed and for me I think 1% is in the noise but you have to make your own decision based on your airplane.

Almost everything under the cowling requires cooling otherwise you could just tape those openings over on the front and pick up some speed. Unless we're violating the 2nd law of thermodynamics every energy conversion is less than 100% energy efficient. This applies to conversions from gas to mechanical energy (your cylinders), and mechanical to electrical (whatever you use to generate electricity). This means that heat is a byproduct and that heat needs to be liberated. This is why you have cowling inlets and blast tubes on various things under the cowl. The unit is capable of dealing with the temperatures under the cowling but it generates heat on it own that needs to be removed. The question is how much and how the cooling resource gets allocated, this additional cooling duct is in the noise for me.

For me, the additional cooling is easily justified by the other advantages of this device, mainly weight and size savings. Race pilot Dave Anders, didn't even hesitate to save 3 lbs and have the additional cooling load. He also reports that he gets more power on taxi than he did with his vacuum pad alternator. I can report that even in 115 F OATs, after a heat soak during a fuel stop, his unit was still within temperature limits that I am comfortable with. Big thanks to him for going out and sweating in those conditions.

Field testing:
There are ten prototypes in the field. Below is a list of the types of planes, and who has them. If you know them, please feel free to contact them. Most have authorized me to put prospective buyers in contact with them, so contact me if you would like to talk with them and I'll make the connection. In three cases I did the installation myself but for the rest of these I provided the manual and they were able to install it with very few or no questions. In one case, basically all I heard back was "All good so far, no issues" (Paul Rosales).

RV-8 - Bill Judge (Primary power, alternator is backup)
Please don't ask me how long it took to develop this thing.

Tailwind - 2021 Raspet Awardee [google that] (sole means of power)
Are you sure you want to be associated with me?

Harmon Rocket - Adam Pontius (Backup, dual electronic ignition)
Flawless.

RV-4 - Paul Kessel (Backup, dual electronic ignition)
Completely good! If you want to use me as a reference for people to call I am fine with that as well!

RV-4 Dave Anders (Backup, dual electronic ignition)
I think you’ve got a winner.

RV-3 - Wheeler North (Backup, dual electronic ignition)
Don't you want me to pay for this?

RV-10 - Rich Jankowski (Backup, IFR platform)
RV10, LYC IO-540 BU DC generator performs flawlessly! Easy to install!

RV-10 - Joe Waltz (Backup, IFR platform)
Glad to report that all testing has gone well.

Lancair IVP - Bob Pastusek (LOBO founder, long time Maintenance officer, 28V version on a continental TSIO 550, backup power for an IFR platform)

N437RP, a Lancair IV-P based in Ft Worth, TX. Bob Knuckles “model Z” dual 28 volt electrical system. The alternator normally runs in “on-line standby” mode at an output voltage just less than the primary alternator. In this mode it outputs 1-2 amps continuously to aircraft systems. If the primary alternator fails or is taken off-line, the standby automatically picks up the full steady-state power requirement of 14-15 amps during daylight ops and 18-20 amps at night.
I could not be happier with it!!

RV-6 - Paul Rosales (backup power)

I can’t thank you enough for this and giving me great great great peace of mind! Rosie

Letting someone else put something in your airplane is a huge decision. All of these guys volunteered and I'm incredibly grateful for that. Big thanks to all of them. They are all still running them.

I see two use cases for the MZ-30L:
1. Primary power for a magneto ignition day VFR plane where minimum weight is a priority.
2. Backup power for planes that are dependent on electrical power whether that's dual electronic iginition or IFR.

I think that the MZ-30L can do both well in almost every case, but every application is going to vary and have compromises: Such as spending $995 vs $100 at autozone or one vs two 3/4 inch ducts that probably represent a 1% change in cooling capacity.

Please contact me if you're interested: [email protected] or [email protected]. I want to get an understanding of each user's application before I sell them a unit and make sure that it is right for them. My website will eventually support online purchases.

Here is the boilerplate info about the unit:

Monkworkz, LLC is proud to introduce the MZ-30L(Patent Pending) for Lycoming and similar engines. A clean sheet design to aircraft power that leverages the most recent advancements in power electronics and electromechanical machinery. The MZ-30L is a 30 amp, 3 pound, vacuum pad driven generator for 14 volt electrical systems. It can be used in backup or primary power applications and is optimized for easy installation on experimental aircraft.

The MZ-30L has several features that simplify installation and add capability, including:

• Self-exciting: no external phantom current needed to generate power.
• Fast (~5 ms) electronic current limiting backed up with an integrated fuse. No need to have a panel mounted breaker or oversized “ANL” type fuse in line. Connect directly to the electrical bus wherever convenient such as the switched side of your contactor.
• Integrated current shunt: read current from a shunt provided with the device.
• Integrated current measurement with proportional voltage output: 0-4.4 volts that scales linearly with current out for input to EFIS/EIS systems or other device.
• Compact design with a compact shear coupling: Generator depth is less than 4 inches from the vacuum pad face. Diameter is less than 2.5 inches.
• Intelligent integration with other power sources: in a backup power application the MZ-30L actively monitors bus voltage and comes on line ~200 ms after bus voltage drops below spec.
• Remote Enable: Allows installation of pilot operated switch to enable/disable the device.

*Also available: 28 V versions, and versions for Continental engines where the vacuum pad RPM is 1.5 times the crankshaft RPM.
~15 amps available at 1000 rpm on engines where the vacuum pad RPM is 1.3 times the crankshaft RPM, 30 amps available above 1800 crank RPM

Congratulations

Bill, congratulations on this product - it looks really cool. It's clear a lot of thought and hard work went into creating it, and I wish you lots of success!

This sounds very interesting. I'm building a Bearhawk and would like a backup power source. I won't have my engine for about a year so don't need this yet, but when I do, I'll contact you!

monkworkz said:

Cooling:
It does require one more cooling duct than a traditional alternator (per Vans instructions). The cooling duct provided is identical to Vans duct material for an alternator. The duct inner diameter is 0.65", that is around 1/3 of a square inch in area. Estimating what sort of loss of cooling is difficult. How much area do all the passageways between the pressure side and exit side of the cowling add up to? For rough comparisons the inlet area of my cowling is around 64 square inches (two inlets, ~4 inches high x ~8 inches wide), so we're talking about adding something that is less than 1% of the inlet area. My engine temps are well managed and for me I think 1% is in the noise but you have to make your own decision based on your airplane.

Click to expand...

Bill, I really like the product concept. Can we address the above?

The system requires two blast tubes, one for the rotating unit and one for the regulator, so total leak area 0.66 sq in.

The comparison area of interest is the passage area of the bypassed heat exchanger, i.e. engine fin passage area, not cowl inlet area. I've attached an illustration for a 390 angle valve, old stuff from my hard drive. The total for the whole engine is about 23 sq in, so the new leak area is about 3%. Note a parallel valve cylinder has a little less passage area, so the leak area percentage will be a little higher for a four cyl, and a little less for a 540.

That's just polishing the pins, because leak area comparisons don't present the whole picture. Before being purchased by Continental, ECI's Bobby Looper told us, as measured on the Airmotive dyno, each additional sq in of leak area resulted in a loss of about 1" H2O deltaP across the engine. It's important to note because there simply isn't much dynamic pressure available in climb. At 100 knots, even with a pressure recovery coefficient well above 1.0 due to prop outflow, the average installation only has about 4" H2O deltaP. Losing 0.66" leaves 3.34, in theory about a 16% loss during climb, when it's really needed. The loss percentage would only drop during cruise, when available dynamic pressure increases by the square of velocity.

So, serious question...can we see temperature plots for flight cycles with and without the blast tubes? Old measurements previously reported here say hot turns with and without blast tubes start out at the same peak accessory component temperature, so I assume max thermal stress is during the first ten minutes or so, when the units begin generating internal heat.
.

Dan

Please check the theory? .66" is the blast tube leak area, not pressure loss from the blast tube? The .66" can not be simply subtracted from the 4" H2O deltaP. The true lose should be less than 5% at any speed.


"At 100 knots, even with a pressure recovery coefficient well above 1.0 due to prop outflow, the average installation only has about 4" H2O deltaP. Losing 0.66" leaves 3.34, in theory about a 16% loss during climb, when it's really needed. The loss percentage would only drop during cruise, when available dynamic pressure increases by the square of velocity."

GM

DanH said:

Bill, I really like the product concept. Can we address the above?

The system requires two blast tubes, one for the rotating unit and one for the regulator, so total leak area 0.66 sq in.

The comparison area of interest is the passage area of the bypassed heat exchanger, i.e. engine fin passage area, not cowl inlet area. I've attached an illustration for a 390 angle valve, old stuff from my hard drive. The total for the whole engine is about 23 sq in, so the new leak area is about 3%. Note a parallel valve cylinder has a little less passage area, so the leak area percentage will be a little higher for a four cyl, and a little less for a 540.

That's just polishing the pins, because leak area comparisons don't present the whole picture. Before being purchased by Continental, ECI's Bobby Looper told us, as measured on the Airmotive dyno, each additional sq in of leak area resulted in a loss of about 1" H2O deltaP across the engine. It's important to note because there simply isn't much dynamic pressure available in climb. At 100 knots, even with a pressure recovery coefficient well above 1.0 due to prop outflow, the average installation only has about 4" H2O deltaP. Losing 0.66" leaves 3.34, in theory about a 16% loss during climb, when it's really needed. The loss percentage would only drop during cruise, when available dynamic pressure increases by the square of velocity.

So, serious question...can we see temperature plots for flight cycles with and without the blast tubes? Old measurements previously reported here say hot turns with and without blast tubes start out at the same peak accessory component temperature, so I assume max thermal stress is during the first ten minutes or so, when the units begin generating internal heat.
.

Click to expand...

Hi Dan,

I have to be honest, I do not have data on what the difference in CHTs is, I don't have data recording capability in my EMS.

Anecdotally I didn't notice anything. Keep in mind, its not just area, it's also what sort of drag is associated with the path from the pressure side to the exit side, putting a nicely radiused 1 square inch area hole in the baffles is very different than two dozen 5 inch long passages that add up to 1 square inch(like the cylinder fins). Using lengths of corrugated tubes presents substantial drag. And if your CHTs are on the high side you should sort that out before you start adding things to your plane.

The math seems goofy, so if you only start out with 4 inches of water delta P and every square inch means a loss of an inch, then adding 4 square inches means the delta P goes to zero? Add another square inch and suddenly air is going backward out of the cowling? Clearly this isn't the right way to look at the problem!

People add oversized oil coolers all the time, and that would seem to be more area added than we're talking about here.

If this is a hypothetical then its not just the cylinder cooling fin area but also your oil cooler, gaps around the air seal, all those gaps between the cylinders that aren't quite filled by the inter cylinder baffle and all the other blast tube you might have: alternator, fuel pump, mags.

Also, the idea that the area from the pressure side to the exit side is less than the inlet area does match my understanding of what the cowl does: air comes in the inlets and is slowed down, if the there was less area between the pressure and exit side the air would have to speed up again.

Either way, I'll bow out of this and just say it works for me, if your CHTs, and oil Ts are poorly managed then sort that out before doing anything else with your plane.

respectfully,
Bill

Welcome to VAF

Bill, welcome to VAF

A permanent magnet alternator that also self excites? Welcome to 2021!

I wonder though, since many of us already have the B&C 8 amp setup, would you be interested in selling your DC/DC controller box for us to retrofit? I'd be interested in that since I don't need more than 8 amps of backup and already have the B&C.

Thanks,
schu

444TX said:

Dan,
Please check the theory? .66" is the blast tube leak area, not pressure loss from the blast tube?

Click to expand...

Before being purchased by Continental, ECI's Bobby Looper told us, as measured on the Airmotive dyno, each additional sq in of leak area resulted in a loss of about 1" H2O deltaP across the engine.

...so 0.66 sq in = 0.66" H2O loss of deltaP.

I'll be happy to help you measure the loss if you don't believe what Bobby wrote. Piccolo tubes top and bottom, an inexpensive electronic manometer.

monkworkz said:

Hi Dan,
I have to be honest, I do not have data on what the difference in CHTs is, I don't have data recording capability in my EMS.

Click to expand...

Sorry, I wasn't clear. Not CHT...flight cycle temperature of the generator and control board, with and without blast tubes. Can we run them without blast tubes? Do they really make a difference in peak temperature?

From a reliability standpoint, there are 2 things to consider, peak temperatures, and the duration the devices are exposed to those temps. While the unit may survive short term operations at the peak temperatures on a fast turn of the aircraft, but overall life could be shortened drastically by continuous operation at higher temps. In any case cooler operating temps will result in longer electronics device life.

If one steps up to electronics devices that will have longer life at higher temps, the costs escalate significantly.

You have thermistors in the generator.

Any way to tap into them and actually see what the temp of the generator is ?

Regulator on the inside?

Would it be possible to mount the regulator on the cool side of the firewall? Obviously there needs to be some shielding of the three phase (I assume) power coming from the generator. This is the preferred location for the other voltage regulators. Just curious… - Jason

DanH said:

Before being purchased by Continental, ECI's Bobby Looper told us, as measured on the Airmotive dyno, each additional sq in of leak area resulted in a loss of about 1" H2O deltaP across the engine.

...so 0.66 sq in = 0.66" H2O loss of deltaP.

I'll be happy to help you measure the loss if you don't believe what Bobby wrote. Piccolo tubes top and bottom, an inexpensive electronic manometer.



Sorry, I wasn't clear. Not CHT...flight cycle temperature of the generator and control board, with and without blast tubes. Can we run them without blast tubes? Do they really make a difference in peak temperature?

Click to expand...

Hi Dan,

I can't hand over any data that would enable reverse engineering.

What would you do with temp profiles anyway?

The logical sequence of questions would be:
Is that good? Its just a bunch of numbers with no relationship to any meaning.

To interpret the data you would want to know:
What are the materials?
What are the components?

Then you would want to know:
How do they hold up under those temps?

I'm not going to answer these sorts of questions.

As RVDAN mentioned, reliability in electronics is not purely stay under this limit and you're good. The rule of thumb is double the life for every 10 C reduction in temperature which is hard enough to work with when there is so much variability in cycle duration with the homebuilt fleet but in reality it's actually far more complicated than the rule of thumb.

I totally get the desire to push designs further but if that's what you want to do with my gadget I'm not going to assist you the same way Lycoming and Continental doesn't want anything to do with getting 800 hp out of their engines at Reno and Vans doesn't want anything to do with turbo charging their airplanes.

I hope this makes sense to you.

Thanks,

Bill

kreidljj said:

Would it be possible to mount the regulator on the cool side of the firewall? Obviously there needs to be some shielding of the three phase (I assume) power coming from the generator. This is the preferred location for the other voltage regulators. Just curious… - Jason

Click to expand...

It is not recommended, you would need to add a fan to replicate the cooling provided by the baffles.

thanks,

Bill

emsvitil said:

You have thermistors in the generator.

Any way to tap into them and actually see what the temp of the generator is ?

Click to expand...

This falls into the reverse engineering category, you're on your own.

Sorry,

Bill

monkworkz said:

Hi Dan,

I can't hand over any data that would enable reverse engineering.

Click to expand...

For the record, I did not ask any questions about the components.

What would you do with temp profiles anyway?

Click to expand...

The questions were "Can we run them without blast tubes? Do they really make a difference in peak temperature?"

The first relates to a common configuration, an RV-10 with p-mags. A high percentage of 10's cool marginally, and the addition of p-mags means it already has two blast tubes.

The second is merely an attempt to judge effectiveness. I understand peak, dwell, and cycles. "Peak" kept the question simple.

Thank you for your attention.

DanH said:

For the record, I did not ask any questions about the components.

Click to expand...

Sure but temperatures without any context of what components and materials is meaningless. This is like me telling you I had an "engine temperature" of 300 degrees and asking you to let me know if that was "good" but not telling you if that was oil, CHT, or EGT. 300 degrees for all of those would mean something very different from the standpoint of margins over acceptable.

I will say that without cooling the device will "thermally cycle" so if you are Ok with that then sure, don't install the ducts but you can expect it to bump into the temperature limits at various times through out a flight depending on the OATs.

I've destroyed several generators, components and boards doing this development. Thermal limits are imposed as guard rails so the unit does not destroy itself but the duct size was chosen to maintain within thermal limits under any reasonable scenario.

What I will do is measure my cowl delta P at 100 and 150 knots, with density altitude and OAT, with no ducts and both ducts. If there is a measurable difference then I'll do each individually.

Its also worth mentioning that all ducts are not created equal. In both cases I capture the end of the ducts and contain the airflow all the way to where it needs to be, it's not just dumping out nearby.

I ordered a manometer and should have it Thursday but I'm also in the middle of an annual so it may take a week or so before it happens.

If there is enough interest I can pretty quickly make a circuit board and sensor definition file that would allow anyone with a Dynon to use a general purpose input to read cowling delta p in real time.

It seems like there is a dearth of data on this sort of thing but there really isn't any good reason why. It would probably be a significant help to anyone trying to determine if their various CHT fixes did anything useful.

I'll report back.

Bill

What is the range of engine parasitic (for lack of better terms) load in HP? I can back calc the theoretical of course but do you have measured points and standby and full load?

Thanks

E-skate generator

This looks very similar to a generator I made a couple years ago using an electric skateboard motor. I think my motor was a 6374 size but would have to check.
Judging by your dimensions I would assume your generator casing is 63MM. I would also assume it's similar technology. If it is, they do work great. Fairly simple and reliable.

Brandon

kreidljj said:

Would it be possible to mount the regulator on the cool side of the firewall? Obviously there needs to be some shielding of the three phase (I assume) power coming from the generator. This is the preferred location for the other voltage regulators. Just curious… - Jason

Click to expand...

Generators are single phase. Alternators are only 3 phase inside the case, as that is where the rectifiers convert it to single phase. It seems clear from the description that the product is a generator and not an alternator. Generators can be made to self-excite, but to my understanding Alternator cannot, though they can maintain excitation once they have started producing power; Bob Knuckles has a schematic for a simple circuit that performs the self-excitation function on a generator, so not surprising that this new product includes that function.

I have a simple generator and regulator on the pump pad, similar to the B&C 8 amp. My regulator is behind the Firewall and did nothing more than twist the supply wire pair. I have no noise issues.

Lary

monkworkz said:

Sure but temperatures without any context of what components and materials is meaningless.

Click to expand...

Again, the request was merely to judge the effectiveness of the blast tubes.

I will say that without cooling the device will "thermally cycle" so if you are Ok with that then sure, don't install the ducts but you can expect it to bump into the temperature limits at various times through out a flight depending on the OATs.

Click to expand...

Likely highest temperature will be after shutdown on a hot turn, when a blast tube has zero flow. We've already seen that data in relation to p-mags and Slicks.

What I will do is measure my cowl delta P at 100 and 150 knots, with density altitude and OAT, with no ducts and both ducts. If there is a measurable difference then I'll do each individually.

Click to expand...

Excellent, and I'll be glad to help if you wish. I have a decent library of pressure measurements from various owners, all gathered with the same setup and procedure so the data is reasonably comparable aircraft to aircraft. That said, I have not cut any 1" openings in my baffle wall to check Bobby's report.

Two keys; piccolo tubes to average static pressure across the whole space while ignoring dynamic pressure. The how-to is here:

https://www.danhorton.net/Misc/COWL PRESSURE AND TEMPERATURE MEASUREMENT.doc

Each set of pressures is taken while flying a standard NTPS three-leg, which sets an accurate aircraft velocity regardless of conditions. Fly three or more sets, graph them, and results can be compared:

https://www.danhorton.net/Articles/Cooling Efficiency.docx

Its also worth mentioning that all ducts are not created equal. In both cases I capture the end of the ducts and contain the airflow all the way to where it needs to be, it's not just dumping out nearby.

Click to expand...

Fair point, and I agree.

BTW, a few weeks ago I dropped climb CHTs on a nice RV-7 by 30~40 F. Taped over three standard blast tubes and two gaps at the tapered part of the Titan cylinders on 3 and 4. Unlike your shrouded components, the blast tubes were the usual sad case, blowing freely, and not even pointed at the alternator and Slicks they were intended to cool.

I measured at 100 and 150 knots IAS, at 100 knots the most I see is 0.2 inH20 loss from letting the holes from the ducts remain completely open. Saturday I did runs with the two ducts and with the duct holes taped over, didn't see a difference at 100 knots, and a small difference at 150 knots. Monday I went back and did three runs:

1. duct holes completely open, so no drag from attached ducts, should be worst case
2. ducts installed, should be better than run 1 because of drag and restrictions presented by the duct corrugation and termination in to restricted area.
3. Duct holes completely sealed off, should be best case, no extra air let out from the baffling.

On the Monday runs at 100 knots I see 0.2 inH20 less pressure out of 5.3 inH20 in my plane, that is 3.7%. Small but honestly more than I expected.

Something I noticed afterward was that power setting would change the delta p dramatically, by several inches depending on the situation. Descending with the throttle back at more than 120 knots would show less than 3 inches, climbing at 100 knots full throttle would show more like 6.5 inches rather than the ~5 inches in steady state, level, at 100 knots. Clearly the prop forcing air into the cowling has an big impact and I didn't intentionally try to control for throttle setting between runs, this could easily be the 3.7% difference between runs and the reason for the dead heat one day and a small difference two days later.

All runs were at 2500-2700 MSL, Saturday runs were hot and the DA was 5000-5400, 88-91F. Monday runs it was cooler, DA was 4000-4250, 73-77 F. runs were all at 100 or 150 IAS. I did my best to average the values measured while on speed.

As far as the airplane is concerned my setup is stock, no plenum, just the standard air seal and an IO-360, 1500 hrs service over 15 years.

The initial instrumentation set up with piccolo tubes had huge variation from one reading to the next so I put syringe ends with the needles broken off about 1 foot from the sensor in both lines shoved down inside the vinyl tubing with a grill skewer. The small orfice and fixed volume on the sensor side serve as a means to smooth out the measurements.(thank you RVDan) Even still the measurements on the meter would vary by up to 0.5 inches of water. The syringes I had access to were either 28 gauge and something smaller like 31 gauge would be better. All measurement were with the same setup using the 28 gauge orfices.

Pictures of calibration, setup, ducts and video of measurements are here. I also added comments of what I trying to show and estimates of what I see as the average pressure differential measurement for each run.

I'd like to do more testing with 31 gauge needle orfices added to the setup but that can't happen until October for me.

Bill

I'm running a B&C 30 amp permanent magnet "dynamo" on my C85-powered aircraft. That 30 amp dynamo is considerably larger in outside diameter than the one we're seeing here, and perhaps similar in depth.

No matter its size, I just love the B&C product because it's so simple. No belts, no brushes, no hassles.

I sincerely hope this product produces results at least as good as the B&C product I'm currently running. If it does there are going to be a lot of very happy customers.

I'll go out on a limb and say a generator like this might just push me off the fence and cause me to install a second electronic ignition system. Everything I'm seeing so far makes me believe this product from Monkworkz will be a positive addition to our small arsenal of terrific electrical products available to the Experimental community.

Hello Bill,

The practical aspects of good measurements are always the most difficult to sort out.

Flying just after dawn minimizes physical factors.

What you're trying to measure is less than the meter's scatter. In addition to the restrictors, maybe an accumulator volume? That manometer may have an averaging function you can bring into play. Measuring upper and lower pressures separately can also help, because one leg of the manometer is connected to the airframe static system.

Noticed the manometer timed out and shut down in one of the videos. Probably can't zero it on startup with the hoses connected. Shutdown is likely based on time since the last push of any button, so one workaround may be to simply cycle the units on a regular basis.

Looks like the Dynon needs some airspeed calibration, as it does not agree with the steam gauge ASI. The steam gauge is probably the correct one, based on the deltaP's you're currently reporting. Not a big deal in the context of deltaP comparison, but it may be worth looking into. In past cowl pressure measurements, the plan was flying the NTPS 3-leg at three speeds, then graphing the results. That made everyone's results reasonably comparable, with zero reliance on airspeed indications.

Yes, propeller outflow is a major factor in climb cooling, so you will need to also stabilize on a particular power setting for all comparisons.

Interesting subject. I have a spare trim servo in my parts bin, so I may rig an air door to open and close a known leak area. Two pressure measurements 30 seconds apart on the same flight would eliminate a lot of variables.

Of course, it would be easier to simply log the temperatures to see if the blast tubes are necessary, through hot soak, taxi, climb, and cruise. Tubes or no tubes, the units will reach the same max temperature in the hot soak.

Bill, plan B, in case you get tired of the manometer.

I had pretty good success using a sensor when measuring the nozzle air bleed deltaP for a constant flow FI system. Used a Honeywell sensor and a Dataq DI1000 to feed my laptop. I'd need to dig back through the sensor configurations to see if they have one with a suitable range for plenum deltaP. Only real catch is needing someone in the back seat to run the laptop, just because there isn't enough room to operate it on the front pit of our RV8's.

Pretty darn accurate. The two attached plots are live intake port pressures for 720 degrees of crank rotation at 2400 RPM, i.e. the wave action in the intake tube and sump plenum.

https://www.dataq.com/products/di-1100/

I've got one on my RV-10. Works as advertised. Highly recommend.
Small, light, easy to install. Perfect as a backup for me.
I've flown 100 hours with it and never noticed any appreciable differences in temps.