201 Speed

[Critter]

Greetings all,

Having just purchased a 1977, 201 this weekend, I was wondering what speeds l should be.

I had some decent headwinds all the way home so never saw more than 130 knots true, but feel that my new bird should be a few knots faster.

At 2500ft it was indicating138 knots at 2400 24" and about 143 knots at 2500 25" both times just rich of peak

I am not too concerned, as l can see several areas where l shall be able to speed the old bird up, for starters, the paint was really dirty and needs a good polish. The other fact is that it has upper and lower rotating beacons on the tail section, these are the old extra large motorised beacons, there should be several knots to gain by removing the lower unit and later the upper.

I also think that the plane needs rigging, both ailerons are trailing up by 2", whatnis normal? I shall also check that the gear doors are flush

Apart from the speed issue, the flight went well, l had never flown a mooney before, I am looking forward to loading the family in and discovering further remote areas of Australia, l can see that l shall own this plane for quite a while, it has new leather seats, new carpets, new plastics along with decent avionics.

Regards

Chris

[Jeff_S]

G'day Chris. Speeds on a J model will vary by many factors, some of which you've highlighted. I'm not sure why you say it was only showing 130 KTAS based on the indicated airspeeds you give in the next sentence. Both of those are already higher than 130 and since you had a little bit of altitude, the TAS would have been marginally higher than the IAS.

 

One big factor will be how you decide to run the engine, notably running ROP for best power or LOP to get greater economy. I'll give you my general speeds but since my plane has a different weight factor, 3-blade prop and our engines are probably not exactly tuned alike, this is just guidance. But at a standard altitude of 8,000' running 100 ROP I can get the bird up to between 155-158 KTAS, but that's burning anywhere from 12.5 to 14 GPH depending on conditions. At 10-20 LOP, same altitude, I'll get 150 KTAS on the nose, burning 9-9.5 GPH.  So I choose to save a bunch of gas and go just a bit slower.

 

Your mileage will vary, but good luck figuring it all out.

[FAST FLIGHT OPTIONS LLC]

"I had some decent headwinds all the way home so never saw more than 130 knots true"

...your true airspeed will not change due to a headwind

[88drvr]

I was thinking the same thing with regard to true airspeed. A quick and dirty conversion from indicated to true is 2% per thousand feet. In this case 143 ias would be 150 tas. I wonder if you meant "true" as actual ground speed?

[Jamie]

Go higher...Lots higher.  Get out of indian country. Higher == faster.

[Steve Dawson]

Proper rigging and aligning the engine by shimming the mounts helped me pickup some speed. I can true out at 159 KTAS at 8K and 10-11 GPH at 2500 RPM

.

[MARZ]

The thing that struck me odd was "both ailerons are trailing up by 2" - you sure the flaps were up??

[Bob - S50]

As mentioned, don't confuse TAS with GS.

 

With that said, we have a two blade J.  At a few hundred pounds below gross we seem to get about 155 KTAS at 8500', 2400 RPM, full throttle, about 20 LOP, and a fuel flow of about 8.7 to 9.3 GPH.  That's assuming our TAS indicator makes the correct calculations and our OAT is accurate enough for setting the correct values in the airspeed indicator.

 

Enjoy your new plane.

[HopePilot]

Check your rigging, asap!  Also possible that you didn't retract the cowl flaps all the way after the climb...or they are currently rigged to trail for cooling (when in the closed position).

[kmyfm20s]

New owner here, first annual coming in a few months.

Just curious, how can we tell if the engine is sagging or how much we need to shim the mounts if it is? Where will I find a written reference? What reference can I use to study up on proper rigging. Local mechanic here is pretty good and worked for a Certified Mooney Service in the past ... so I am thinking we might be able to do that here ... ?

just wanting to educate myself a little.

http://www.donmaxwell.com/publications/MAPA_TEXT/Alining%20Engine%20Using%20Shims/ALIGNING_YOUR_ENGINE.HTM

[Critter]

Hi guys,

Thanks for all of the responses. It was late when l started the topic, a couple of corrections: I was only doing 130 knots ground speed because of the head wind, they were pretty strong winds! What indicated airspeed should l be seeing at 2500 ft at the above power power settings? I need a goal to set myself to improve the machine back to book standard.

Other things:

Cowl flaps definitely closed, engine looks close to aligned, wing flaps were up.

As with the rigging, something is wrong with the ailerons trailing up. The plane recently had the aileron bellcranks replaced, this is a good starting point. I did not think it was normal for the ailerons to be up.

Thanks again.

[FAST FLIGHT OPTIONS LLC]

What indicated airspeed should l be seeing at 2500 ft at the above power power settings?

Chris. I'm not following....Why are you so concerned with indicated airspeed? No two airplanes will have the same indicated airspeed as this is going to be dependent on not only altitude but temperature as well. Individual installations will also cause this to vary. It's not a real accurate reflection of performance. Indicated airspeed in the plane you just purchased becomes real important when your landing.....be careful and consider finding a Mooney knowledgeable flight instructor that could help you figure things out.

Remember its easy to go fast in these planes. The hard part is learning how to operate them at the other end of the speed spectrum. Thats where people usually get into trouble. Good luck

[bumper]

It's hard to add much to something written by Don Maxwell. 

 

But a bit more on the "201 cowl riding up" issue. The 201 rides up due to aerodynamic forces. This results in paint chipping and abrasion along the rear of the upper cowl half. At the rear of the bottom cowl, forward pulling stress tends to tear the upper portion of the boot cowl.

 

Years ago, I developed a stainless steel strap "fix" for this, and gave the idea to Paul Lowen at Lake Aero Styling and Repair. The strap ties into the rivit line going aft and provides an AN nut plate for an additional #10 countersunk screw at the bottom rear of the lower cowl - - no more tearing. 

 

I also made a fix for the upper cowl, two glassed in hardwood wedges, one each side at the rear edge to butt up against two small SS angle brackets screwed to the upper firewall lip. These keep the 1/16" spacing across the back of the upper cowl to prevent chafing and chipping. I think Paul felt that part of the fix was unnecessary . . . maybe not, but it does work well for sure, even if it might be overkill.

 

Prior to my strap fix (that I think LASAR still sells), Paul experimented with replacing the rear floating fastener brackets with fixed ones, but IIRC, that fix, mentioned by Don, didn't work all that well.

 

I found Don's article most helpful and my engine sits nicely aligned thanks to him.

 

Next time I have my cowl off, I can take some pictures if requested.

 

bumper

[jetdriven]

LASAR's cowl strap fix has fixed Camloc receptacles on the upper boot cowl. I dont know if these are necessary, and they may even wear harder on the cowl holes.

[bumper]

Jetdriven,

 

I know that before LASAR got the strap fix, Paul was changing out the floating receptacles for fixed ones. My distant recollection (this was in the mid 90's, so I might be off on this) is that when I gave them the strap part of the fix, along with the wedge they didn't use, Paul allowed as to how the fixed camlock receptacles were not always doing the job alone. I was not aware they continued with the fixed camlocks as well as adding the strap. Couldn't hurt I guess.

 

What I do know from my own albeit limited experience, is that the SS strap, along with the glassed in wedges for the upper cowl, completely solves the cowl "ride up" issue without the need to modify the factory fasteners - - other than adding the two #10 countersink screws w/Tinnerman washers to tie the lower cowl to the SS strap (and of course, riveting the SS strap in place.

 

bumper

[Bob - S50]

Critter,

 

Back to your original speed question.  Take a look at your POH in the performance section.  My '78J says for 2000' MSL, 2400 RPM, and 23.6" MP, the airplane should true out between 149K and 153K.  Using the 2% rule, that would be 141K-146K indicated.  The range in speeds is for differenct weights.  Also, CG location could make a difference.  With a forward CG (front seats full and no bags) you'll need more down force on the tail which will also require more lift from the wings, both of which will increase drag.  Still, your 138K indicated is pretty close to the book value.

 

The values I listed above were for economy leaning, which by the way, is just about the worst thing you can do to the engine.  According to my POH, economy cruise is 25 degrees ROP.  Everything I've read says that is just about exactly the point of highest internal cylinder pressure and the highest CHT.  I would personally lean to peak EGT, LOP, or if you want to run ROP I'd go to at least 100 ROP.

 

I read a rule of thumb for the J that you might find interesting.  If you add the RPM in hundreds and MP together and get 47, you're pretty close to 65% power.  For example 2400 RPM and 23", or 2500 RPM and 22" or 2600 RPM and 21".  Also, if they add up to 50 you'll be close to 75% power.  2500 RPM/25"

[wiseng]

78 J.  I usually flightplan mine for 155 kts anywhere from 7-9k running 50 ROP using the 50 rule for 75% 47 for 65 etc, and burn bout 10-11 Gal/hr.  If I want to go lean I lose about 8 kts and burn 8-9.  Last time I did a 4 way gps check full out @ 6000'with the ram air open I averaged 165 kts. 

 

As stated above get your POH out and see how she does against the factory numbers.  You will not get 175 Kts i generally see about 8-10 knots slower than published numbers.  YMMV, 

[PeytonM]

Bumper et al, I'd be curios about your photos of the cowl fix. I'm taking my 1989J in for Annual next week, and was going to provide them with the Lake Aero cowl fix kit. Has anyone had experiences with whether this kit fixes the "cowling riding up" issue? Sounds like there might be some permutations of the kit to include "glassed in wedges." Have not seen that available commercially. Thanks in advance for the advice. Peyton

[bnicolette]

Bumper et al, I'd be curios about your photos of the cowl fix. I'm taking my 1989J in for Annual next week, and was going to provide them with the Lake Aero cowl fix kit. Has anyone had experiences with whether this kit fixes the "cowling riding up" issue? Sounds like there might be some permutations of the kit to include "glassed in wedges." Have not seen that available commercially. Thanks in advance for the advice. Peyton

 

I had the kit installed on my airplane and my cowl is completely stationary!  It definitely does not ride up anymore.  

[201er]

Brett, can you email me details about this, prices, results? Appreciate it.

[bnicolette]

Brett, can you email me details about this, prices, results? Appreciate it.

Mike I'm just putting it on here since there is some interest in it.

 

I got the kit from LASAR part # (LCOWL) $60

 

Henry Weber's installed the kit and it was 5 hours labor.

 

I had the engine shimmed while it was there with new lord mounts and the spinner sits perfectly up to the cowl (Note that the 5 hours labor is strictly for the install of the kit).  The cowl does not move and whenever taking it on and off always fits right back up perfectly to the spinner and stays there.  I used to have to pull the cowl down after every flight before the kit.  After the kit there is zero shift.  I highly recommend it.

[jetdriven]

Bumper et al, I'd be curios about your photos of the cowl fix. I'm taking my 1989J in for Annual next week, and was going to provide them with the Lake Aero cowl fix kit. Has anyone had experiences with whether this kit fixes the "cowling riding up" issue? Sounds like there might be some permutations of the kit to include "glassed in wedges." Have not seen that available commercially. Thanks in advance for the advice. Peyton

 

That LASAR cowl fix kit fixes the problem but I do not like the fixed nutplates. You guess where they should be and rivet them to the upper boot cowl, but I think they wear on the holes more. Im going back to floating nut plates and the angle channel / stopper block idea that Bumper had.

[bumper]

Jetdriven,

 

I haven't seen the LASAR version of the fix. My version does not replace any original fasteners. It does add a SS strap*, not visible when installed, that slides under the existing skins and ties into the Cherrymax rivet line going aft on the boot cowl at that point. A single #10 countersink screw with Tinnerman washer goes into a new hole drilled near the bottom of the lower cowl and into the nut plate carried by the SS strap. Not even noticeable when looking at the plane as the new screw and washer is almost on the underside of the cowl.

 

*My strap was the original prototype, it works well but like many such things, you make one and then realize there's a better or simpler way to make the next. Thus mine is more complicated than it needs to be and the strap sold by LASAR is simpler.

 

I will take photos when I de-cowl for the annual next month.

 

bumper

[OR75]

looking forward to seeing the photos ... I do not understand the description above  

[kmyfm20s]

Bump for Bumpers photos!