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Glide ratio on Maules

Posted: Fri Mar 31, 2017 9:57 am
by TomD
I was reading the release notes on this whizzy new feature on ForeFlight, "Glide Advisor".

I realized that I have no formal number on the glide ratio of my M5-235C w/ micro-vortex generators.

I have a visual idea as where I will "run out of air" but no number to put into an app.

I know on floats it was always throw out a brick and follow it down.

Any wisdom here? I am sure if there are "published" ratios for different models those probably would be handy for other folks.

TD

Posted: Fri Mar 31, 2017 10:13 am
by Mountain Doctor
No data Tom but I use the glide ratio for a 172. I figure that would put us in the ballpark. So I figure 1.5 NM glide for every 1,000' AGL.

I am interested in this Foreflight feature as well.

Posted: Fri Mar 31, 2017 10:15 am
by Mog
Hah, I started search this two days ago as well with no certain info so far. Wish I had a full set of V speeds for my M4.

Posted: Fri Mar 31, 2017 2:34 pm
by TomD
Doc said:
I use the glide ratio for a 172
That is probably close for a M7 where the extra two feet of wing bring it closer to a 172 than a M5. Also hanging the O540 out front has to change things vs a 4 banger.

Posted: Sat Apr 01, 2017 8:23 am
by Flyhound
I've been meaning to conduct a "bootstrap" analysis of my Maule's performance. This is a spreadsheet flight data collection process that allows an owner/pilot to generate climb and glide graphics for their plane at different loadings and conditions. Since you collect the data for your plane, it is responsive to any mods you have made and the current condition of your engine. It takes 2 to do this safely. One to fly specific climbing and gliding maneuvers, and one to record the data. Read about it here:

http://www.allstar.fiu.edu/aero/ba-background.htm

And here:

http://www.avweb.com/news/airman/182410-1.html

Kitplanes magazine had a good article about the process a couple of years ago. Unfortunately, the book giving detailed instructions is out of print, but online resources still provide adequate instruction.

Posted: Sun Apr 02, 2017 2:10 pm
by Njacko
Hi Tom,

Last time I checked (MX-7-180 with Bushwheels) it was about 1 in 6, or 1 mile for every 1,000 ft height. In my machine, that's roughly in line with the top of the cowling.

Peter.

Posted: Tue Apr 11, 2017 5:09 pm
by PCH
In error, I started a glide ratio topic on pilot lounge. Here is my last post there:

I did a little test flying this weekend. My plane is a M-4 220c with 850s and no vortex generators installed. The testing was done with engine off, prop stopped and as feathered as possible.

Although my check list said 80 MPH was the best glide, I found that 70 MPH IAS provided both the best glide and lowest sink rate at both 0 and 20 degrees of flap. Best glide with 40 degrees of flap occurred at 60 MPH IAS.

Best glide L/D was 12 with 0 degrees of flap and 10.5 with 20 degrees of flap (both at 70 MPH IAS).

For my plane, if it turned into a glider, I would fly 70 MPH IAS, 0 flap till committed and plan on a L/D of 10 (and hope the engine hadn't quit in a downdraft).

I would be interested in seeing other people's findings.

Posted: Sun Feb 24, 2019 10:51 am
by Joe-FBS
Just for fun:

Interesting result today from measuring the glide performance of our MXT-7-180 using data logged by the app' CFI Tools. Setting flight manual best glide speed (79 knots) with propeller fully coarse, the data logged suggests a glide ratio of 1:14. I would be tempted not to believe such a high value except that on Friday I did the same test in a PA28-161 and got 1:10 which is, as far as I can find, the book value (there being, as far as I can find, no book value for the Maule).

Rate of descent was about 600 feet per minute.

Not sure that I believe this but interested in opinions.

Posted: Sun Feb 24, 2019 10:55 am
by Joe-FBS
PS the aeroplane is aerodynamically standard.

We were two-up with main tanks full and reserve tanks empty so something like 980 kg (2200 lb) and mid-CG.

Posted: Sun Feb 24, 2019 11:36 am
by Kirk
Long discussion on this in a previous thread:

http://maulepilots.org/forums/viewtopic ... io&start=0

At that time I started using 1.5 nm/1,000’ for my M5-235 with 8.50s, no vg installed.

The book figures for best glide and min sink are a good starting point but airspeed indicators seem to be just a guide in the low speed regime. Best to do a little testing on your own for your aircrafts numbers.

I found no difference in pulling prop back to coarse pitch since there is not enough oil pressure at idle to overcome the springs in the hub that drive the prop to low pitch. Slowing enough to stop the prop rotation then resuming glide resulted in a 100 FPM improvement in sink rate.

Kirk

Posted: Mon Feb 25, 2019 8:26 am
by Mountain Doctor
Mountain Doctor wrote:No data Tom but I use the glide ratio for a 172. I figure that would put us in the ballpark. So I figure 1.5 NM glide for every 1,000' AGL.

I am interested in this Foreflight feature as well.
Exactly what I do.

Tested with windmilling prop flaps zero and 83 MPH seems about right.

Posted: Mon Feb 25, 2019 9:10 am
by Flyhound
Due to the lack of TO/Landing distance information, climb rate data plots against density altitude, and other performance information in the Maule POH, I bought the EAA's Flight Test Manual and test data cards. I'm just going to build my own POH addendum as if I was flight testing a home-built. It will have the added advantage of capturing the as-is performance data for my plane and engine rather than generic information generated for a "standard" model configuration.

Posted: Mon Feb 25, 2019 6:21 pm
by Rezrider
Mine glides like a brick. I just plan accordingly!

Posted: Mon Feb 25, 2019 6:27 pm
by Mog
Wow, wish mine glided like a brick!!

Posted: Tue Feb 26, 2019 7:13 am
by DeltaRomeo
Can't find it now, but I read somewhere that best glide is usually half the difference between Vx and Vy. So for most of us without wing mods, the 83 mph figure would be about right.