Ragsf15e

Antares, that's one fast F model! That's got to be 10+ knots faster than the average bird. You're getting your money's worth out of those mods at that speed!

Tony - Just curious, why so low? You could be a lot more efficient up around 9-11,000' at full throttle, RAM on, and LOP. Your speed would be around 140 kts as the 4 pages of this forum can attest to. Rags

You guys have me laughing pretty hard... especially the part about brain surgery vs rocket science and the whole post about LOP, ROP, T&GOs, Flaps, etc. Worth reading all 4 pages of this thing just for that. Ok, I think Bob has nailed the easiest way to do this accurately that we can all agree on and do fairly simply - go fly, turn roughly into the forecast wind, fine tune your heading until GPS ground track and aircraft heading match (i.e. get pointed directly into the wind), note ground speed, turn exactly 180 degrees (perfect tailwind), stabilize and note ground speed. The average of these two numbers is a pretty accurate take on your TAS. If you don't like this method, someone can read the attached document which is the most confusing and complicated method of determining TAS that I could find, but it does handle important factors like "curvature of the earth"! Rags vol4no3_A01.pdf

Someone nailed it about 5 posts ago... the easiest way is to fly in calm air! Or maybe to fly directly into the wind... however, that pretty Aspen displayed wind value is using your pitot system because it uses IAS, temp, and pressure to figure TAS, then uses TAS, GS, HDG, and Track to figure the winds. Sorry to our mathologist, but I wasn't talking about CAS being affected by a crosswind. Here's why holding a ground track (say North) will always be slower than holding the same HEADING (North) with any crosswind... You will have to crab into the crosswind to hold your ground track. That will always increase the headwind component (if it was a headwind or direct cross) or it will decrease the tailwind component if it was a quartering tailwind. No matter what, holding a ground track crabs you into the wind and slows your forward progression.

Bob, copy, you're right, I didn't see the couple of important distinctions in your data. I'd still like to see a 3 way test to take out the pitot error. Jerry - I'm no "mathologist", but flying 4 ground tracks instead of headings is not negating the wind. In fact, you're probably going faster than indicated by the test, so that should make you feel good. If you fly a ground track you must be crabbed into the wind to hold the track - probably on all four legs unless two of them happen to be directly into/away from the wind. The greater the crab, the less your TAS down the intended track. Imagine flying with a 100kt direct crosswind. You'd be pointed something like 40 degrees into it to hold a track and you're now using 60 of your 140 knots TAS just to hold you against the wind. Get a strong enough crosswind and you have to point directly into it just to avoid being blown across your track and you won't be moving along that track at all. Unless we're talking about strong winds, I doubt there's more than a knot or two difference in the 2 or 3 methods talked about here, but I still think the 3 way test is the most accurate since the Navy Test Pilot School has some papers posted online about it with a lot of squiggly math symbols that I forgot 20 years ago. We need a mathematician on Mooneyspace! Rags

Marauder - that's one heck of a nice panel! However, I do like my "older model" engine controls and the removal of my "steam gauges"!! Rags

Yep, Bob, you posted just as I was writing... I agree, the Aspen data is only as good as the inputs whereas the ground speed test is much more accurate.

Bob - First, that's a beautiful panel on your E model! I have to say though, I don't think your Aspen displayed TAS is too accurate. First, you got a higher TAS at 9500' than you did at 8500'. 7-8000' D.A. should be right in the sweet spot for our max speeds (not for the turbo crowd). Higher should be slower according to data and the book numbers. My real problem with the Aspen TAS is that it's using your 50 year old pitot system for the IAS input. As I found on mine, it's off by about 6 knots at cruise. I'd recommend doing the GS test and verifying the accuracy of your TAS like Super Dave. Also, the pitot system error is most likely off different amounts at different speeds - so maybe 1 knot at 80 knots on final, but 6 knots at cruise. I do drool over your panel though... Rags

That's some good data and you guys have some fast airplanes! Super Dave, I'm glad you've checked the TAS on the Aspen vs TAS derived from a ground speed check because I found that TAS indicators or TAS computed on your GPS can easily be corrupted by your pitot system. The real data we have has to take the calibration error from the airspeed indicator out of the equation. The only good way to really do it is the 3 way (or maybe 4 way) test. Thanks for the feedback! Rags

Yeah, that's a good one. I read all those several times before choosing my M20F. He got pretty good speed out of that F model - around 150KTAS at 7000' with no speed mods. I think that might be a bit more than most of them are capable of (mine included) and I'd like to see some other data points too. Interestingly, my IAS was almost exactly what his was (123KTS at 10,500 and 129 KTS at 7,500) but if you use the temp and pressure to turn IAS into TAS, I find that my airspeed indicator is showing about 6KTS too fast - calibration error maybe? Anyway, the 3 way groundspeed test is very accurate. I used the pilot report above, put 3 of his directions into the 3 way test and get about 1 knot slower, so they aren't far off of each other.

Ok folks, we all fly Mooney's to go fast. My 1968 F model goes a few knots less than book (I know book was optimistic), but I'd like to get a few comparisons to see if it's about the same as others or if my 16 year old engine overhaul is starting to catch up with me. So here's what I did, I flew a speed test at 10,500 and 7,500 and I'm putting the results below. If anyone else has a chance, I'd like to know how your bird comes out on a similar test. The only speed mods I've got are the sloped windshield and the Lasar cowl closure (which cools nice, but I doubt it goes any faster) The speed check is very accurate and you only need 3 legs, 90 degree off - like North, East, South. You just write down the GPS groundspeed on each leg. It's actually more accurate than doing all 4 directions and averaging because it uses math to take out the crosswinds you'll have. The calculator is at http://www.csgnetwork.com/tasgpscalc.html. If you note the temp and altimeter setting it'll also give you the density altitude and the actual winds. I used 100' ROP for the test (although I normally run LOP which is ~6 knots slower). I used WOT, 2500 RPM, RAM air on for both runs. Weight was about 2400 lbs. My 7500' TAS was 142.6 Knots and the density altitude was 9465'. My 10,500 TAS was 139.9 Knots and the density altitude was 11,951'. Thanks for anyone that wants to use this as an excuse to go fly and report back! Rags

I checked it out on skyvector. Look on the legend, it says "minus values indicate surface up to but not including the value." Looks like exciting airspace. When i go vfr places like that, I will usually be on flight following and ask for permission to enter the class B even if there's a way to get to the destination without. That at least gets you legal even if you stay out of it. Controllers really have been good with it.

I'd also check the HSI vs the 430W "test screen" (that's not what it's called, but close). When you first turn on the 430W and it asks if you want to refuel/hit ok, you should be on the screen that says something like 1/4 deflection left, 1/2 deflection low or something like that. Look at the HSI and see if it's actually indicating as it should. I have a similar problem and my A&P and I used this as a starting point to figure out that the HSI wasn't responding to the 430... we slipped in another 430 he had laying around and it worked perfect... thus my 430 glide slope was the problem. You can also get to this calibration (maybe) page somewhere in the 430W aux menus. Good luck!

Jakl - I see the Chiefs patch, "the other squadron at Seymour"... I'm a former Rocketeer and now have an M20F (at Laughlin AFB). Like some of the others above, I'd recommend trying sitting in an M20J with your wife and see how it feels. I'm 6'3 and 170lbs. It's comfortable once I'm in, but it's a bit of "yoga" to get into the left seat. Forget about getting in the back. If you're going to take your dog(s) and/or snowboards, fold down seats will be a must. Mine don't, and I kind of wish they did. My M20F has about 635 lbs load left with full fuel (64 gal), but really, you don't need all that gas. 3 hour legs are plenty unless you plan on using piddle packs. Let me know if you want more info. I just went through the whole buying process about 4 months ago, so it's fresh. It's an awesome airplane to own and fly! Rags

Seth - You're right on all three counts... the brightness is adjusted by twisting, you can press to test them, and the F is a great airplane! Thanks for the input. Rags

Tony and Hank (and the others too... ) - Thanks for your responses. That cleared up my understanding of the mechanism. I'll definitely take the next opportunity when the belly panels are off (no single piece panel here) to check it out. I'll also not take the rigging for granted. That's one of the reasons I had DMax do my pre-buy and annual when I bought it this year. I think I'll keep using a good MSC to keep myself out of trouble. Thanks again! Rags

Yep, I read through the 1968 POH and the gear indications are slightly different than I'm use to in the more "modern" aircraft I fly... The red light in the M20F is on continuously when the gear is retracted. The green light is on when the gear is down and locked. I guess my question is more about where the sensor is for these indications? I realize the gear are mechanically linked, but is there any failure mode that would have a green indication when all 3 weren't completely down? Is the green indication on only 1 gear and it assumes the others? According to the manual, the floor indication works on the same principle as the green light, so it indicates the same thing. Thanks, Rags

Hello, I have a 1968 M20F that was modified with electric gear at the factory in 1968. It has 3 gear indications - a green light and a red light on the panel, and the green "gear down" indicator on the floor between the seats. What exactly do these mean? If the green light is on, are all 3 gear down - i.e. is there a squat switch on all 3 gear and the light doesn't come on unless they are all good? Is there a switch on just one gear and they are all assumed down if the one gear is good? What about the red light? It's on when I pull up the gear... does that mean all my gear are up and the nose gear doors are closed? I'm just curious so that I'm more ready to deal with any faulty indications or problems before they happen. Thanks, Rags

Bucko - I had a very similar experience in Denver earlier this year with my new to me M20F. It was about 8,000' DA, so I leaned prior to takeoff, but I didn't know exactly how much to lean it. Took off with it too close to "max power" and quickly got ~425 on the CHTs and ~220 on the oil temp. I have a JPI930, so I could see it all happening pretty quickly. I increased mixture and all the temps fell right back down toward a normal climb. Since then I've played with the "target EGT" method on other high DA takeoffs and found ~1250-1300 EGT works for my plane. When leaning prior to takeoff, I can get the EGT up to about 1450 or so, but then I enrich it back to 1250-1300. Climb temps work out just fine. I'd encourage you to try this technique and see what target EGTs work for your setup. Like the previous posts said, this temp should be somewhere around the sea level, full rich takeoff EGT. Good Luck! Rags

Andy - That would make sense. I'll take a look at the probe type next week while changing the oil. Thanks!

I've only had my "new" bird for about 2 months, so I'm still getting use to her, but I've noticed that the #1 cylinder runs much cooler than the other 3. Like 50+ degrees cooler. Is this ok? Is it just because it's up front and getting the lion's share of the airflow? Is something wrong? I've got a 1968 M20F. The engine has ~590 hours SMOH (but it was 15 years ago). It was modified with GAMIs about a year ago (~.4 spread). I've been running it ~20 LOP once I get up to altitude and it seems to make good power and is smooth. It has an EDM-930 which I downloaded and will post my recent flight which was just tooling around the local area (up to 6,500) and then a few night patterns. You can definitely see that #1 is much cooler from start all the way through the flight though. #2/#3 are usually about the same and much hotter than #1. I set the graph bar to a time when I had it leaned for cruise so the temps on the upper right were fairly stable. Any thoughts?

You guys are awesome. Thanks for the info - I wasn't aware of the new antennas. Couple of good points about waiting to see how the whole part 23 TSO vs non-TSO equipment shakes out and reasons not to remove the vacuum system too. Thanks again guys, your experience and knowledge are awesome. What did people do before the internet? Rags

Thanks for the feedback. I want to get rid of the vacuum system because I like the reliability of the electric and/or solid state ADIs. I'd also prefer not to have to worry about the vacuum pump going out every so often. Definitely moving the VSI under the altimeter. That was the first question I asked when looking at the aircraft, but the owner was ready (he'd asked too). The King HSI that's in it is square all the way back and won't fit in the spot under the ADI so it had to swap with the VSI. Actually the GPSS was one of the things I was wondering about too... I think it's standard on the Aspen PRO, so I'm guessing that will be through the Aspen, but I'm not sure. There are lots of reasons I'm looking for a shop in Texas that has done a few of these in Mooneys... Maybe Chris will chime in if he's already done something similar?

I knew when I bought my "new" 1968 M20F model a couple months ago there would be a few upgrades I'd like to do. She's actually got a very nice panel, good interior, and serviceable paint, but after a few recent IFR flights around Texas, I think I'm about ready to put in an Aspen PRO PFD 1000. I think I'll be $$ limited to just the one screen for now. I was hoping someone out there would have some experience with this and give me some round number estimates or even a recommendation for avionics shops with Mooney/Aspen experience (I'm based in SW Texas). Here's what I've got to hook up to it... STEC 30 with Alt hold, Garmin 430, and a Garmin SL30 #2 NAV/COM. I'd like to remove the whole vacuum system when I do this, so I understand I'll have to purchase an electric B/U ADI. What am I missing? Anyone have any clues how much it will cost, where I should go to do it, or what else I need to do to get rid of the vacuum system? Thanks so much for your help, I'll attach a current panel picture just in case you want to see what the previous owner did for me (thank you!)! Rags

As usual, thanks for the inputs! I appreciate your time and thoughts. I'm so excited to get in my new plane, I'm sort of thinking past the insurance checkout, but if I'm paying that much, I hope to get something out of it!