m5-235 cruise speed

txmaule · Post by **txmaule** » Sun Jul 06, 2008 4:11 am

i'm looking to find out what speed other m5-235 owners are getting out of their planes
at 23 squared i'm only getting 118 kts. A couple people said I should be closer to 130 (but one of them was the seller).
If you'all are getting considerately higher speeds then I'll have to look to see what I need to do

thanks in advance,
skip k.

a64pilot · Post by **a64pilot** » Sun Jul 06, 2008 7:13 am

I think your'e talking indicated and maybe others are talking true. That can be a big difference.

txmaule · Post by **txmaule** » Sun Jul 06, 2008 8:04 am

a64pilot wrote:I think your'e talking indicated and maybe others are talking true. That can be a big difference.

Jody,
the 118 kt speed is true off the gps, flying different headings and then averaged out.

skip

210TC · Post by **210TC** » Sun Jul 06, 2008 10:51 am

What was your indicated airspeed and altitude?

210TC · Post by **210TC** » Sun Jul 06, 2008 11:08 am

I just checked my #'s and 118 indicated I consider a little above cruise on 8:50's.
I don't think it makes any difference that I have a 4 cylinder engine.
Check this: http://maulepilots.org/forums/viewtopic ... 34&start=0

Kirk · Post by **Kirk** » Sun Jul 06, 2008 1:29 pm

23 squared should give you a lot more than that.

Mine with the O540-J1A5D cruises 132 KTAS at 75%, might get as high as 137 down lower.

65% is more like 125 KTAS

That's for an M5-235 with 8.50s, clean airframe with a fair number of antennas on it.

Kirk

210TC · Post by **210TC** » Sun Jul 06, 2008 1:56 pm

Kirk,
What kind of fuel burn do you have at those speeds? At my noted speed I will be from 10 to 11.5. This is without a fuel flow gauge.

a64pilot · Post by **a64pilot** » Sun Jul 06, 2008 6:32 pm

Somethings wrong. Rigging way out of wack? I flew 60 hours in two weeks and consistantly trued out between 132 and 136 kts with an M-6, and I think you should be faster than me. That's calculated on an E6B from indicated. If your GPS has an E6B, just plug in the numbers, it does the calculating. Garmins have this feature.

Kirk · Post by **Kirk** » Mon Jul 07, 2008 3:42 am

Mines burning 11 to 12 GPH at 65% and 13 to 14 GPH at 75% This is 1 to 2 GPH higher than the Lycoming manual says it should.

That's calculated since I have no fuel flow gauge, but is very consistent. I've checked the tach etc. (it reads high but I correct for it) and 100 ROP at 75% and at peak for 65% and less.

I'm a bit suspicious that I am gettting poor fuel vaporization from the carb. It is original and is 31 years old. Idle RPM and mixture are correct.

Kirk

210TC · Post by **210TC** » Mon Jul 07, 2008 5:40 am

Your 100 ROP could be the extra fuel burn.
My Harmon Rocket had fuel flow, EGT, Etc. and I would lean it up to it shaking, back off a little "LOP". This would save me roughly 2 GPH.
Again, I only lean at cruise and never at or near WOT.
I flew in a friends plane to Mexico not long ago and it had an injected Conti that I could lean until the engine would go away without any vibration. COOL.
My Maule #'s are posted on the dash by the prior owner as 9 GPH at 50/55% power roughly 2200 RPM/28" MP. I could never get better than 10 GPH at that setting. Our #'s are very close, I rarely cruise at 75%, so I have no #'s.

A64, I use indicated airspeed and Gps. I try to stay away from True Airspeed as it is never close to my speed across the ground.

210TC · Post by **210TC** » Mon Jul 07, 2008 6:31 am

Here is an example: Click on picture.
First, 19,000 ft, Indicated 97KTS, KNS80 indicates 153KTS= 176MPH ground speed.
Second, 20,000ft climbing at 200fpm, 145kts=167MPH ground wish I had the indicated on this one.

UP-M5 · Post by **UP-M5** » Mon Jul 07, 2008 11:29 am

i am on 29" bushwheels and a big tailwheel, with all gear fairings removed , lower strut fairings off, some extra float brackets hanging off the belly, and an IFR antenna farm- so this isn't the best comparison....
my M5-235 at 23 squared with 30 gallons and 2-3 people (typical light load) shows 117-119 kts indicated (around 135 mph) down low in summer. that is burning roughly 13 GPH.

210TC · Post by **210TC** » Mon Jul 07, 2008 11:54 am

Txmaule,
Seaport sounds close to the coast. If so, the high humidity and temp will slow you down. I don't know how much, but I sure noticed the difference when I moved from California to Florida.
Those guys up in heaven "Alaska" have really good conditions when it comes to density altitude situations.
I read about high humidity, but it took away more than I thought it would when you add 90+ degrees.
Just one thing to think about.

a64pilot · Post by **a64pilot** » Mon Jul 07, 2008 5:48 pm

True airspeed and ground speed should be identical in a no wind situation, or I'm confused as to the meaning of true airspeed.

maules.com · Post by **maules.com** » Mon Jul 07, 2008 6:06 pm

Over the years, I have found that an M5-235 with 7.00x6 tyres and simple antennas, no vg's, will true airspeed at 160mph, provided 59deg F sealevel temp with standard lapse rate and 75% power at 7500msl if I remember right re the altitude. This is at 2400rpm where most people don't operate continuously.
TAS being the only way to compare speeds provided the ASI is accurate

m5-235 cruise speed

m5-235 cruise speed

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