Lasar speed mods and flush riveting

[Capt_CrashN_Burn]

Was talking with an "F" owner today, he claimed that the Lasar cowl enclosure for the A-G models doesn't produce the 4-6 knots improvement that it claims to. Is there any truth to this? if so, how many other Lasar speed mods don't produce the gains that they claim?

Another thing, have Mooney engineers ever heard of these fasteners called flush rivets?? It seems to me you could pick up at least a few knots by using them. Or do they not make much difference??

[231Pilot]

Look at the pre 1968 or 1970 C Mooneys (can't remember which, but I think 1970) and at the J Mooneys.  They are held together with flush rivets.  After Mooney changed hands the new owners abandoned flush rivets on the C as a cost cutting measure.  They really didn't care if the C was a little slower because it was not the top of the product line.  The top of the line in every model year that I know of had "clean wings" with flush rivets.  I am probably wrong in some details, but I know our forum members can and will provide the corrected information.

You gotta love a Mooney, it is still efficient even when flush rivets are not used.

[richardheitzman]

Every "Speed Mod" that everyone sells, flap gap seals, engine cowling, reverse brake mount, dorsal fin, slope wind shield, etc produces a increase in speed. BUT some more then others. Engine cowling and smooth belly mods produce the greatest gains.

When Lopresti came into Mooney and took a look at the aircraft, he produced a very clean "aerodynamically (sp?)" aircraft. The M20J. Flush rivets are a waste of money and time AFTER the boundry layer on the wing and fusalage (SP?? come on coffee kick in!). The M20E (I have been told) either a 66 or 67 has the "cleanest" wing.

 

[rorythedog]

in the real world, after a certain point a few knots either way doesn't amount to much. i once put flap/gap seals on a cherokee 140(a lot of money at the time) and was disheartened to find that i couldn't tell any difference in my trip times.  there are so many variables to consider that a couple of knots is meaningless.

when i take off at sunrise in my m20j i can be a long way from home by the time it sets. i enjoy the time.

[Lood]

The cowl closure didn't result in any speed increase on my F. In my personal opinion, the best speed mods are tha 201 style cowling and windshield mods.

[Immelman]

My 66E has flush rivets for approx the first 2/3 of the wing chord. The fuselage skins are dimpled for flush fasteners for the windshield and windows. The cowl fasteners are flush... I could be wrong but as I recall, just about everything else is not flush riveted.

[Capt_CrashN_Burn]

Quote: 201Pilot

Look at the pre 1968 or 1970 C Mooneys (can't remember which, but I think 1970) and at the J Mooneys.  They are held together with flush rivets.  After Mooney changed hands the new owners abandoned flush rivets on the C as a cost cutting measure.  They really didn't care if the C was a little slower because it was not the top of the product line.  The top of the line in every model year that I know of had "clean wings" with flush rivets.  I am probably wrong in some details, but I know our forum members can and will provide the corrected information.

You gotta love a Mooney, it is still efficient even when flush rivets are not used.

[Capt_CrashN_Burn]

Quote: richardheitzman

Every "Speed Mod" that everyone sells, flap gap seals, engine cowling, reverse brake mount, dorsal fin, slope wind shield, etc produces a increase in speed. BUT some more then others. Engine cowling and smooth belly mods produce the greatest gains.

When Lopresti came into Mooney and took a look at the aircraft, he produced a very clean "aerodynamically (sp?)" aircraft. The M20J. Flush rivets are a waste of money and time AFTER the boundry layer on the wing and fusalage (SP?? come on coffee kick in!). The M20E (I have been told) either a 66 or 67 has the "cleanest" wing.

 

[Capt_CrashN_Burn]

Quote: Lood

The cowl closure didn't result in any speed increase on my F. In my personal opinion, the best speed mods are tha 201 style cowling and windshield mods.

[Capt_CrashN_Burn]

Quote: Immelman

My 66E has flush rivets for approx the first 2/3 of the wing chord. The fuselage skins are dimpled for flush fasteners for the windshield and windows. The cowl fasteners are flush... I could be wrong but as I recall, just about everything else is not flush riveted.

[flight2000]

I agree with the 201 windshield mod.  I know the cowl enclosure provided me with slighty cooler cht's, which is what I wanted it to do.

Here's the best picture I could find of my 67 E's wing that shows where the transition from the flush rivets starts.  I know it's not in person, but it'll give you an idea until you can find a local one.

Brian

[thinwing]

Flush riveting on laminar flow wings (as found on mooneys/bonanza/barons)I have seen used only on first 2/3rds of wing and fuse...Ive seen this on my m model and beech baron I used to have.I donot recall who it was that explained boundry layer effect on these wings ,but the main idea was because flush riveting was moore labor intense...every rivet hole required countersunk holes they were only used where drag effects mattered...The entire airframe could be flush riveting as they did in ww 2...one of the reasons for japanese zero performance for modest horsepower was flush riveting...kpc

[Capt_CrashN_Burn]

Quote: flight2000

I agree with the 201 windshield mod.  I know the cowl enclosure provided me with slighty cooler cht's, which is what I wanted it to do.

Here's the best picture I could find of my 67 E's wing that shows where the transition from the flush rivets starts.  I know it's not in person, but it'll give you an idea until you can find a local one.

Brian

[MooneyMitch]

As far as the LASAR cowl enclosure, Paul Lowen has stated clearly to us in different forum settings, the only true value of his enclosure is for asthtetics.  From the horses mouth so to speak.   

[rbridges]

Quote: Lood

The cowl closure didn't result in any speed increase on my F. In my personal opinion, the best speed mods are tha 201 style cowling and windshield mods.

[Immelman]

I had always heard that the cowl closure improved cooling air-flow. I can't speak for comparison as it was on my airplane before I bought it, but anecdotally I can tell you that I have a cool running IO-360. It is seldom that I see CHT > 350dF in cruise in all but the warmest atmospheric conditions.

[eldeano]

A look at the '63 wing and Powerflow exhaust.

[Capt_CrashN_Burn]

Quote: eldeano

A look at the '63 wing and Powerflow exhaust.

[eldeano]

Dunno if I flew it, it might get dirty!!

Seriously though, it seems like it would be hard to compare because a lot of the later models are stretched heavier more powerful etc. ! I guess an aerodynamic expert with a nice wind tunnel could tell you. But it seams that with a laminar flow wing like a Mooney it would make a significant difference.  I have heard though that although the stretched models are heavier they have less forward drag for some reason. 

I would drill out all of my flush rivets replace them with regular rivets and find out for sure putting an end to the conversation, put with the holidays and all I'm a little busy.

[eldeano]

http://www.pilotfriend.com/aircraft%20performance/Mooney/31.htm

[Capt_CrashN_Burn]

Quote: eldeano

www.pilotfriend.com/.../Mooney/mooney.htm 

[HopePilot]

Not to change the subject, but how do you like the Powerflow?

[eldeano]

Quote: HopePilot

Not to change the subject, but how do you like the Powerflow?

[rbridges]

Quote: eldeano

Powerflow is great, I would highly recommend it. Brings your 180 horse close to 200.  Seems to be good for four or five knots. 

[carusoam]

Eld,

Nice link...  I learned something new....

"TCM IO-550-G (280 HP). Normally aspirated with large 6-cylinder engine. Flying Magazine's single-engine plane of the year for 1994. Extra long body."

M20R - Plane of the year.  I'll be looking for a copy of Flying Magazine....

Best regards,

-a-