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Search: Posts Made By: Cumulo
Forum: Glass Cockpit 03-20-2021, 08:32 PM
Replies: 7
Views: 835
Posted By Cumulo
well it has not been mentioned yet in this...

well it has not been mentioned yet in this thread, but regarding the test numbers by flipmick, the OP, the values described are actually impossible in theory.

If each of 2 points are 30 ohms to a...
Forum: Electronic Ignition Systems 03-08-2021, 01:04 AM
Replies: 12
Views: 2,461
Posted By Cumulo
robust design

Decades age I did design engineering. Down the hall was David Sun who became a zillionaire as Kingston Memory. Good for David. But I had the better real estate in the building though, a glassed in...
Forum: RV General Discussion/News 02-07-2021, 09:13 PM
Replies: 21
Views: 2,142
Posted By Cumulo
Ha. Or like a tuner that keeps calling a guy...

Ha. Or like a tuner that keeps calling a guy named Homer, Henry. Maybe may exhaust fumes? :)

I did the exhaust sys on an original 180 Lyc acro. It was 4 into nothing with 1 5/8 tubing. It sounded...
Forum: Alternative Engines 02-07-2021, 07:07 PM
Replies: 95
Views: 9,173
Posted By Cumulo
Yes

+1

Real numbers spoil everything.

Free Macro Assembly?
Forum: RV General Discussion/News 02-07-2021, 05:48 PM
Replies: 21
Views: 2,142
Posted By Cumulo
At ease. I think the error come from the way...

At ease. I think the error come from the way "cycle" is used in engine speak.

A cycle generally means a circle back to where one starts such as a yearly cycle of spring, summer, fall, winter.

In...
Forum: RV Building Tips/Techniques 01-25-2021, 11:50 PM
Replies: 14
Views: 1,446
Posted By Cumulo
Good question. Maybe have to ask GRT. A standard...

Good question. Maybe have to ask GRT. A standard location on many cert aircraft is poking out of the left side of the windshield as you said.

Impact air at SL at RV cruising speeds gives a pressure...
Forum: RV General Discussion/News 01-20-2021, 03:08 AM
Replies: 27
Views: 2,411
Posted By Cumulo
isentropic vs adiabatic expansion?

Expanding a gas through the blading of the inlet guide vanes of an axial compressor, which was one of your points, could possibly produce much more cooling effect than a throttle process..
I...
Forum: RV General Discussion/News 12-27-2020, 05:49 PM
Replies: 21
Views: 2,536
Posted By Cumulo
aerodynamics

Humm, a bottom mounted antenna that would serve that function could easily be designed. The gear leg is mentioned. Possible.

All of the trainer aircraft of WW2 that I am familiar with such as...
Forum: Propellers 12-24-2020, 12:45 PM
Replies: 40
Views: 4,644
Posted By Cumulo
With hat in hand, I'll offer this to the bright...

With hat in hand, I'll offer this to the bright group of people on this thread regarding torsional vibration. Higher compression ratios or advanced timing will make "peakier" power pulses. Though...
Forum: COMM 12-18-2020, 12:05 AM
Replies: 12
Views: 1,597
Posted By Cumulo
Agreed. Using a signal splitter to...

Agreed. Using a signal splitter to separate/combine the GS and VOR/LOC is a misapplication, a ~4db loss minimum and maybe a lot more. A good diplexer will be almost lossless for both bands .

Was...
Forum: Alternative Engines 12-16-2020, 02:14 AM
Replies: 81
Views: 7,379
Posted By Cumulo
Well, how about this? Hydrogen is here.

https://www.cnet.com/roadshow/reviews/2020-hyundai-nexo-review/

The Hyundia Nexo. Hydrogen fuel cell/ lithium battery. 161 HP, 291 ft lbs torque. Cool.

Buy one(~$60K), strip the motor, fuel cell...
Forum: Alternative Engines 12-14-2020, 10:29 AM
Replies: 81
Views: 7,379
Posted By Cumulo
won't happen

Bad, bad old arithmetic. It takes the fun out of everything, even my longing for an imagined quiet, comfortable electric airplane.

IC engine ~36% efficient (Carnot, another bad hombre in the world...
Forum: RV Ongoing Maintenance Issues 11-30-2020, 07:55 PM
Replies: 13
Views: 2,049
Posted By Cumulo
+1 I agree. Symptoms say sticking exhaust...

+1

I agree. Symptoms say sticking exhaust valve. Stuck intake will cause much more commotion. You have covered most other possibilities I believe.
Further, if an exhaust valve sticks and stays off...
Forum: RV General Discussion/News 11-30-2020, 03:38 AM
Replies: 12
Views: 1,660
Posted By Cumulo
Low pitch angle stop

Coupling the high idle speed and the fact that the a/c glides like a stone, it is most likely an unadjusted /mis-adusted low angle stop. Common rookie mistake.

Follow the approved data, of course...
Forum: Alternative Engines 11-24-2020, 04:53 PM
Replies: 63
Views: 9,348
Posted By Cumulo
Steve, you are correct. My first thought in...

Steve, you are correct. My first thought in reading the thread regarding putting the heat on the leading edge surface was that it would trip the boundary layer to turbulent. Maybe a skin radiator...
Forum: Traditional Aircraft Engines 11-24-2020, 02:45 PM
Replies: 17
Views: 1,923
Posted By Cumulo
+1 Yeah, Zero drop. Key switches have had their...

+1
Yeah, Zero drop. Key switches have had their probs with AD's, SB's. It would mean no ground on 2 positions.

The left-right temp is likely an indicator prob - grounds, etc. IMHO. Big temp diffs...
Forum: Traditional Aircraft Engines 11-24-2020, 02:13 PM
Replies: 17
Views: 1,923
Posted By Cumulo
I am stumped as well. The A&P card in my pocket...

I am stumped as well. The A&P card in my pocket doesn't help either. All of the clues point to mag timing being too advanced. But you have triple checked that to 25 deg, right? The amount of...
Forum: Alternative Engines 11-24-2020, 02:01 AM
Replies: 63
Views: 9,348
Posted By Cumulo
Even in theory, you can not get a zero drag heat...

Even in theory, you can not get a zero drag heat exchange from a skin radiator. Adding heat to the boundary layer will increase skin friction significantly. I think Hoerner covered this somewhat in...
Forum: RV General Discussion/News 11-14-2020, 06:51 PM
Replies: 25
Views: 4,232
Posted By Cumulo
Using Dan's very reasonable assumption of a flat...

Using Dan's very reasonable assumption of a flat torque curve at that rpm, tweaking the prop to get 2700 rpm will increase the power by 2700/2600 or 3.85%. Assuming power required at hi speed with...
Forum: RV General Discussion/News 11-12-2020, 12:37 PM
Replies: 62
Views: 8,433
Posted By Cumulo
Literally off the back of an envelope: at 200...

Literally off the back of an envelope:
at 200 mph, pressure rise ~5%, temp rise ~1.3% or
~7 degrees F.
I don't know what venturi effect is with an air scoop.
Forum: Propellers 10-24-2020, 08:09 PM
Replies: 14
Views: 3,856
Posted By Cumulo
Van's comment, etc

Some really good comments re fixed pitch, particularly Mr. Van G's on the front page with Propman and others in the thread.

I have used Javaprop to do light a/c prop design simulations for many...
Forum: Glass Cockpit 08-21-2020, 01:46 PM
Replies: 11
Views: 2,099
Posted By Cumulo
GTP-59 clone

In another thread I sketched out how to clone a GTP-59.
https://vansairforce.com/community/showthread.php?t=175216&page=2

The GTX is designed for a platinum RTD type temperature probe only. An...
Forum: RV General Discussion/News 08-07-2020, 12:18 PM
Replies: 13
Views: 4,632
Posted By Cumulo
I've read Sig Horner's DRAG cover to cover...

I've read Sig Horner's DRAG cover to cover several times, done wing section optimizing with Xfoil, etc.l and , so I am very familiar with the aero mechanisms at play here. I also find this subject...
Forum: Traditional Aircraft Engines 08-04-2020, 04:25 PM
Replies: 30
Views: 4,721
Posted By Cumulo
OK, troy ounce = 31.1034768 grams av. ounce =...

OK,
troy ounce = 31.1034768 grams
av. ounce = 28.3494 gram
pound = 453.592 grams
Forum: Traditional Aircraft Engines 08-04-2020, 04:13 PM
Replies: 30
Views: 4,721
Posted By Cumulo
Yes, that is certainly at least part of the...

Yes, that is certainly at least part of the answer. However, the major difference is actually proof that our process of compressing lead into gold is polytropic. At least, that is what my...
Forum: Traditional Aircraft Engines 08-04-2020, 05:52 AM
Replies: 30
Views: 4,721
Posted By Cumulo
Recipe for CR

Lotsa good Engine 101 here, but this post is more to the point of the OP's original query, garbled or not, for a chart relating compression ratio (CR) to some measurement.

Typically our aircraft...
Forum: Traditional Aircraft Engines 07-31-2020, 07:35 AM
Replies: 30
Views: 4,721
Posted By Cumulo
If instead, the OP is looking for clearance...

If instead, the OP is looking for clearance volume, the volume above the piston at TDC, the arithmetic is easy. ( Aero Mechanics High School, 1952)

Its Displacement / (CR-1).

So, for an O-360...
Forum: COMM 07-03-2020, 08:21 PM
Replies: 43
Views: 7,901
Posted By Cumulo
I don't want to discourage the use of the archer...

I don't want to discourage the use of the archer antenna, particularly on the nav side by what I've posted, Dale. I hate hair sticking out on aircraft, probably more than most. Using a BNC...
Forum: COMM 07-02-2020, 05:20 PM
Replies: 43
Views: 7,901
Posted By Cumulo
Certainly the Dynon box is not immune to very...

Certainly the Dynon box is not immune to very much EMI in older versions, and I agree, the most direct solution may be to upgraded it. But there is a bit of a gotcha with the Archer installation as...
Forum: RV-12/RV-12iS 06-25-2020, 03:25 PM
Replies: 339
Views: 408,853
Posted By Cumulo
To get through it , I had to add some paragraphs...

To get through it , I had to add some paragraphs to the aux tank recipe Interesting. Hmm. Maybe a 12.
r
Forum: COMM 05-28-2020, 11:54 AM
Replies: 10
Views: 1,143
Posted By Cumulo
Continuing with the cooking theme, aluminum foil...

Continuing with the cooking theme, aluminum foil is as good as a sheet or plate of aluminum electrically at 100 MHz. It can be quite handy for tests. Needs support, though.
Ron
Forum: Electrical Systems 03-04-2020, 12:06 AM
Replies: 17
Views: 2,641
Posted By Cumulo
Powersonic, which was mentioned earlier in this...

Powersonic, which was mentioned earlier in this thread has a quite good battery manual at: https://www.power-sonic.com/wp-content/uploads/2018/12/Technical-Manual.pdf .

It describes floating the...
Forum: Glass Cockpit 02-23-2020, 11:16 PM
Replies: 7
Views: 1,006
Posted By Cumulo
No. Same antenna. No box I know of can swap...

No. Same antenna. No box I know of can swap antennas for ILS. Maybe something amiss with the freg tuning of the ILS. Or maybe not. Your GS showed up, and the LOC and GS are paired. Hmm. Bad box or...
Forum: RV General Discussion/News 02-19-2020, 09:35 PM
Replies: 20
Views: 2,665
Posted By Cumulo
Yes, was a bit confused by the apparent...

Yes, was a bit confused by the apparent contradiction myself. Reread the far's, Fed Register.

Bottom line: The earlier 121.5 TOC91 is no new install. Later TSO C91A 121.5 unit is OK to install as...
Forum: COMM 02-18-2020, 01:59 AM
Replies: 10
Views: 2,165
Posted By Cumulo
As a guy who has designed a lot of circuitry,...

As a guy who has designed a lot of circuitry, waded around in waveguides, magetrons and other esoteric hardware for a long time, I think I've got the subject down pretty well. It has been my...
Forum: RV General Discussion/News 02-17-2020, 11:49 PM
Replies: 20
Views: 3,070
Posted By Cumulo
Thanks Bavafa That HF vac pump should work very...

Thanks Bavafa

That HF vac pump should work very well, maybe better than a football pump that I reversed the valve and piston in. It is good to have a reservoir. I made a vacuum tank from a large...
Forum: RV General Discussion/News 02-17-2020, 11:18 PM
Replies: 20
Views: 3,070
Posted By Cumulo
Good diagnosis by GalinHdz. My response would...

Good diagnosis by GalinHdz. My response would only apply if the static system of Newt' a/c was tight. Galin's assumption is more likely.

Newt's Q: ~Hardly any change when the alt static is opened...
Forum: COMM 02-17-2020, 08:10 PM
Replies: 10
Views: 2,165
Posted By Cumulo
Being well versed in the reciprocity rules of...

Being well versed in the reciprocity rules of radio communication, I am puzzled by the differentiation being applied to transmitting and receiving here. Transmitter protection circuitry kicking...
Forum: Alternative Engines 02-17-2020, 07:05 PM
Replies: 40
Views: 14,198
Posted By Cumulo
Wink Nostalgia

Thread made this old man look up Nikasil. Looks good. Requires diamond honing.

Bought an almost new Vega once with the engine parts in a box. Got a block with the stepped sleeves. Six on the...
Forum: RV General Discussion/News 02-17-2020, 06:06 PM
Replies: 20
Views: 3,070
Posted By Cumulo
Good question. It likely indicates a very well...

Good question. It likely indicates a very well sealed cabin area - if we are talking RV/low wing.

The pressure inside the fuselage will be the sum of all the openings to the outside and the...
Forum: RV General Discussion/News 02-17-2020, 04:47 PM
Replies: 20
Views: 3,070
Posted By Cumulo
Yep. Don't ask me Why I know. ron

Yep. Don't ask me Why I know.

ron
Forum: RV General Discussion/News 02-17-2020, 04:27 PM
Replies: 20
Views: 3,070
Posted By Cumulo
Quote: Originally Posted by Ironflight View...

Quote:
Originally Posted by Ironflight View Post:
A static leak into the cabin will cause airspeed to read high by maybe 10 knots (I?ve seen as much as 15) at cruise speed in RVs.



Ironflight...
Forum: Propellers 01-27-2020, 01:26 AM
Replies: 19
Views: 4,791
Posted By Cumulo
The two main competing factors which dictate a...

The two main competing factors which dictate a certain tip speed for maximum efficiency are: tip compressibility drag rise, and mass flow through the propeller disk.

We are generally stuck with a...
Forum: RV General Discussion/News 01-21-2020, 12:21 AM
Replies: 21
Views: 2,903
Posted By Cumulo
I did a static port mod years ago on a certified...

I did a static port mod years ago on a certified a/c to improve the airspeed accuracy, so I've been there.
The general effect of fore and aft location of the static port on the aft side of a low...
Forum: RV General Discussion/News 01-17-2020, 01:56 AM
Replies: 7
Views: 1,160
Posted By Cumulo
https://www.kestrobes.com/ltr-landing-taxi-recogni...

https://www.kestrobes.com/ltr-landing-taxi-recogniton-light/

"Powered by 12 to14 volts DC it uses only 1.35 Amps of power. "

So, should work on 14 volts directly.

Ron
Forum: Glass Cockpit 01-08-2020, 07:15 PM
Replies: 26
Views: 3,619
Posted By Cumulo
I could have been a bit more clear. Equipping ...

I could have been a bit more clear.
Equipping with a radio like a Val nav unit to cover the legalities of IFR operation is often suggested. It ties in really nice to a G5 for VOR/LOC/GS. A 2nd...
Forum: Glass Cockpit 01-08-2020, 12:04 PM
Replies: 26
Views: 3,619
Posted By Cumulo
Several sage observations in this thread. A...

Several sage observations in this thread. A question of my own:

A VHF nav unit is often suggested as an economical path to the part 91 requirements for IFR.

Since the 75Mhz marker systems which...
Forum: Fuel Injection Systems 11-09-2019, 07:31 PM
Replies: 28
Views: 5,062
Posted By Cumulo
I like the direction you outlined, Bob. I've been...

I like the direction you outlined, Bob. I've been thinking along similar lines
of duplicate systems. It looks like a single injector in the 100 lbs/hr area
would be needed to get 180 -200 hp. ...
Forum: Fuel Injection Systems 11-07-2019, 08:54 PM
Replies: 28
Views: 5,062
Posted By Cumulo
sorting it out

Re: open source EFI

I ran across another open source EFI thread that could have
possibilities for aircraft application. RUSEFI.COM.

It is more focused on making a unit that is in the direction of...
Forum: Fuel Injection Systems 11-02-2019, 10:29 PM
Replies: 28
Views: 5,062
Posted By Cumulo
I reviewed the Speeduino project. I like. Open...

I reviewed the Speeduino project. I like. Open source. Testing software, good support, cheap.:)

I am an Elektoniker, so your reference to a reostat connected throttle position sensor gave me some...
Forum: Fuel Injection Systems 10-28-2019, 12:17 AM
Replies: 28
Views: 5,062
Posted By Cumulo
Thanks. Nice heads up on the SpeedDuino project....

Thanks. Nice heads up on the SpeedDuino project. Looks good as a solid jumping off point for an a/c engine control.

Collaboration on things like hardware, packaging, wiring, connectors,...
Forum: Glass Cockpit 10-19-2019, 12:48 PM
Replies: 16
Views: 5,288
Posted By Cumulo
Hi Peter The sensors I used have leads, so the...

Hi Peter

The sensors I used have leads, so the mounting would be similar to using the AD590- .

The easiest mounting for most applications would be to solder the device to the cable wires and...
Forum: Glass Cockpit 10-18-2019, 11:54 PM
Replies: 16
Views: 5,288
Posted By Cumulo
My entry into this Inexpensive Temp Probe Derby...

My entry into this Inexpensive Temp Probe Derby is based on a thin film platinum device from, you guessed it, Digikey. Suprisingly, they are cheap, accurate, but also very tiny.

I thought some of...
Forum: RV Building Tips/Techniques 10-06-2019, 12:31 AM
Replies: 28
Views: 18,437
Posted By Cumulo
Well, a bellmouth, a funnel, whatever, may give...

Well, a bellmouth, a funnel, whatever, may give you more rain, more bugs, more dirt, but not a bit more pressure. Not fair is it? Not intuitive either. :D

BTW, I am a Free Diffusion advocate. It is...
Forum: Glass Cockpit 09-13-2019, 11:55 PM
Replies: 8
Views: 1,616
Posted By Cumulo
Steel connector on a magnetometer

Well, I discovered a few days ago that my yet-to-be-installed Garmin GMU-11 has a STEEL connector shell! It looked like steel, but I was confident that it HAD to be stainless or plated brass just...
Forum: Propellers 09-11-2019, 11:21 PM
Replies: 24
Views: 4,887
Posted By Cumulo
Interesting for sure. But the average Aeromatic...

Interesting for sure. But the average Aeromatic blade is a bit clubby. This soaks up much of the prop's potential.

A modern carbon or refined wood/composite blade would make a big difference. I...
Forum: Glass Cockpit 08-22-2019, 06:24 PM
Replies: 23
Views: 7,100
Posted By Cumulo
can CAN

Seized by the same curiosity as Bob, and for the same reason.

I don't believe Garmin is doing any crypto or other obfuscation on the CAN bus, though its possible. They just don't want things mucked...
Forum: Autopilots 08-04-2019, 09:31 PM
Replies: 19
Views: 4,137
Posted By Cumulo
table-ized settings

More better?
Here are the settings David and I are using:

Dynon default Rick David
ROLL
sensitivity 0 14 14
gain 0 0 ...
Forum: Glass Cockpit 05-23-2019, 01:12 AM
Replies: 12
Views: 2,784
Posted By Cumulo
Interesting. It may be a case of two opposite...

Interesting. It may be a case of two opposite errors compensating and giving the right answer. I assume that your flight calibration is accurate. My money is also on the G5 being right.

My guess...
Forum: COMM 04-24-2019, 02:25 PM
Replies: 25
Views: 3,610
Posted By Cumulo
Mystery

Regarding the mystery of an inactive ELT being able to store GPS data with power off, here is my guess:
It is possible and not uncommon to harvest a little power from the RS-232 signal itself. The...
Forum: COMM 04-20-2019, 11:31 PM
Replies: 25
Views: 3,610
Posted By Cumulo
Glad you asked.:D Well, VSWR or voltage standing...

Glad you asked.:D
Well, VSWR or voltage standing wave ratio is a number that says in its own way the ratio of reflected power; that is, how much power is bouncing back from the antenna.

A bad...
Forum: COMM 04-20-2019, 01:38 AM
Replies: 25
Views: 3,610
Posted By Cumulo
Laying the antenna under a fiberglass fairing of...

Laying the antenna under a fiberglass fairing of a metal airplane is not going to work.

Or, likely, I don't have the picture. The antenna has to be away from the metal structure except at the base...
Forum: Glass Cockpit 04-10-2019, 11:18 PM
Replies: 24
Views: 2,308
Posted By Cumulo
A couple of related points on meeting IFR...

A couple of related points on meeting IFR requirements.

If the , say, G5 is new, the rules give you 24 months from date of manufacture before the part 43 altimeter test is required.

The static...
Forum: Electrical Systems 06-14-2018, 07:30 PM
Replies: 44
Views: 7,511
Posted By Cumulo
Yes, Vern. I bought A CK722 with paper route...

Yes, Vern. I bought A CK722 with paper route money when they first came out. oooooold

It's a positive delight to know there is someone here that knows what a CK772 is, and even has one. Wow.

For...
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