Oleo Struts conversion for Mooney?

[Shadrach]

4 hours ago, A64Pilot said:

You really believe that none of the major manufacturers have discovered the miracle attributes or VG’s? They are ALL stupid? What, nobody’s told them?

VG’s are so easy to get into a TC, call Annie, she shows show up with her DER test pilot, one day to install and conform the installation, one test flight and a couple of weeks and the STC is issued, and with permission of the STC holder, the STC is rolled into the TC, and she will give a manufacturer OEM pricing on the VG’s.

Of course you can roll your own too, there is no Patent.

Not much is easier in aviation, it was the easiest modification I ever did to the aircraft.

For instance leading edge lights used primarily as recognition lights got so stupid that I just gave up

 

I’ll repeat again, I am NOT saying you guys are not telling the truth about what you see on your airspeed indicator, or mistaken.

However any aircraft as it approaches stall angles of attack, the A/S indicator becomes unreliable , as some have seen some light STOL aircraft you can hang on the prop and indicate zero or near zero airspeed.

I’ll bow out of this conversation as I’m obviously not going to change any minds, However just as a general rule in life, question miracle mods that any manufacturer could adapt but doesn’t. like fuel line magnets or “intake vornado’s” or 100 MPG carburetors to name a few for cars during the energy crisis of the 70’s. 

You should change your screen name to Captain Literal! You clearly missed my sarcasm… Reread my post and I think it will become obvious that every word was tongue in cheek. I agree wholeheartedly with your earlier posts. I was attempting to make the same point with hyperbole to the point of absurdity. 
 

I actually did the math and if VG‘s actually added a stall margin of 5kts the M20 airframe would be able to meet part 23 stall requirements at >4000lbs. I don’t believe for a second that it is actually possible. I’m not saying that VGs don’t work, but like most things the delta between the marketing claims and the reality is large.

Edited September 28, 2021 by Shadrach

[1980Mooney]

3 hours ago, Shadrach said:

You should change your screen name to Captain Literal! You clearly missed my sarcasm… Reread my post and I think it will become obvious that every word was tongue in cheek. I agree wholeheartedly with your earlier posts. I was attempting to make the same point with hyperbole to the point of absurdity. 
 

I actually did the math and if VG‘s actually added a stall margin of 5kts the M20 airframe would be able to meet part 23 stall requirements at >4000lbs. I don’t believe for a second that it is actually possible. I’m not saying that VGs don’t work, but like most things the delta between the marketing claims and the reality is large.

Yeah - at your "hypothetical" 4250lbs that would be quite a pig.  High density altitude take-offs would be a real scream.  Reminds me of the Extra 400 with less power. 

[Shadrach]

8 hours ago, PT20J said:

Thanks for posting this Skip. It’s an interesting read. Unless I’m misinterpreting the graph, the J model is truly unique in that its airspeed corrections at low speeds are the the inverse of other GA planes…including my own Mooney. The corrections in your table at low speed show IAS is higher than CAS. It behaves the opposite of my F Model and the PA-24-250 (two POHs I had handy, CAS correction tables below.). Perhaps Roy changed the Pitot angle during the clean up or perhaps it’s all those slick mods…or…maybe someone at Mooney inadvertently reversed the labels on X and Y axis for that POH revision and rather than reprint, left well enough alone figuring no one would notice.

 

Edited September 29, 2021 by Shadrach

[carusoam]

I’ll see your stall speed charts and raise with one from the M20R… 

I would be seriously concerned using the ASI outside of its published range…

The M20R has some pretty low published speed at the bottom of its range…

The difference between CAS and IAS (in the M20R) is quite tiny compared to the precision of the analog ASI…

The biggest difference… A full knot at a 45° bank… between KIAS and KCAS, with gear and flaps down…

Best regards,

-a-

[PT20J]

I've collected POHs from various airplanes I've flown over the years. I never really paid much attention to the IAS/CAS corrections. But, just for fun, I looked up several. In each case, I chose the lowest IAS speed in the chart. If multiple charts/curves were published, I chose landing gear down, full flaps, power off. The first number is IAS and the second is corresponding CAS.

A36 60 64

8KCAB 50 56

C-152 40 43

C-172N 40 48

C-172S 40 50

C-182Q 40 51

C-182T 40 51

C-180K 40 42

C-310N 70 68

DC-3 66 60

PA28-181 50 58

PA28-161 50 56

SR-22 60 58

DHC-2 70 66

M20J 52 50

M20K 55 53

 

 

[carusoam]

Now I can see where A64 was coming from…

Having real data really helps support the discussion…

 

Best regards,
-a-

[PT20J]

So, I was wondering about @A64Pilot's comment that the FAA would require that the airspeed indicator be remarked if the VGs actually reduced the stall speed. I discussed this with Anni Brogan at Micro Aero. Turns out that during the STC approval process, they did not claim any improvement to stall speed and so the STC was approved on the basis that it did not adversely affect any flight characteristic or limitation. While the airspeed indicator markings are listed in the AFM Limitations section, the stall speeds themselves are not. So, there was no need to produce a AFMS. This does not mean that the VGs don't reduce stall speed by 8% as claimed; It just means that the FAA has not verified that they do so.

Skip

[A64Pilot]

20 hours ago, carusoam said:

Now I can see where A64 was coming from…

Having real data really helps support the discussion…

 

Best regards,
-a-

Your allowed errors within certain limits, although I don’t know those limits off hand. 5 ticks a memory, but we indicated in MPH so I don’t know.

The Thrush going back forever is actually faster than indicated, but within limits, and it hurt sales as many think the competitor is faster, but it’s actually instrument error. It’s rumored that back in the day that Piper went though a lot of testing to find a spot that the Pitot tube indicated higher airspeed, but within limits. People will look at an Airspeed indicator and if one model indicates a few kts higher than another, they will of course conclude it is faster, because that’s what they are being told.

Being in the South East we used a lot of the same DER’s as Piper and everybody else in the South East, so everybody hears what everyone else is doing but as we don’t compete, it’s not a problem.

What I did to correct the AS error on the S2R-H80 was to machine a .020 step in the Static port right in the middle, making a step that goes right through the static port hole. This causes a slight vacuum. As Airspeed is actually a measurement of the pressure differential between Pitot and Static it raised the indicated airspeed by lowering Static pressure. I made sure to err on the high side, within limits of course, but high, machining different depths of the step made tuning easy.

It did bring IAS and CAS closer, but if you fly an S2R-T34 in formation with the H-80, the H-80 will indicate 6 or 8 MPH faster, but of course actual speed is the same. The 34 is the airframe that the H-80 evolved from.

The -34 is reading low. the -80 fast, both within limits.

Edited September 30, 2021 by A64Pilot

[A64Pilot]

On 9/28/2021 at 4:13 PM, Shadrach said:

You should change your screen name to Captain Literal! You clearly missed my sarcasm… Reread my post and I think it will become obvious that every word was tongue in cheek. I agree wholeheartedly with your earlier posts. I was attempting to make the same point with hyperbole to the point of absurdity. 
 

I actually did the math and if VG‘s actually added a stall margin of 5kts the M20 airframe would be able to meet part 23 stall requirements at >4000lbs. I don’t believe for a second that it is actually possible. I’m not saying that VGs don’t work, but like most things the delta between the marketing claims and the reality is large.

Sorry about that, I guess I’m a little like Sheldon, I sometimes miss sarcasm.