How Fast?

RobH · Post by **RobH** » Thu Dec 17, 2009 3:31 pm

We're looking at an MT7-235. One of my partners got a chance to fly it today (he's never flown a Maule, neither have I). He just sent me a txt msg back indicating it is a "FUN!!!" airplane. Also noted that the cruise speed was only 120kts, or 138mph.

It has vortex generators. not sure if it has gap seals or not.

Puzzling... The specs on the Maule website indicate a 75% cruise speed of 160mph for the 235 hp model (about 139kts). I wouldn't be surprised if it were say 5-10mph slower than indicated, but 20mph? Perhaps he was talking about the 65% power cruise speed, not the 75%...? Are the manufacturers specs that far off? I realize they buff them up a bit and use a test pilot in free fall, but that seems like farther off than I would expect...

it is a pretty new low time aircraft in good condition. I don't think it is bent or anything like that. NDH, etc.

I'm ok with the speed 'cause it's faster than a 172 and probably gets off the runway better, more utility, etc, but I'm wondering....

Thoughts?

-rh

RobH · Post by **RobH** » Thu Dec 17, 2009 3:38 pm

so I see.... the website notes that is cruise at "optimum altitude" at 70% power...

Is that 7000 feet or something like that, giving a ground speed of 160mph?

Is that the source of the discrepancy?

-rh

Hottshot · Post by **Hottshot** » Thu Dec 17, 2009 4:28 pm

That and it is a tri gear... Haveing that nose wheel will suck alot of speed outa it.

RobH · Post by **RobH** » Thu Dec 17, 2009 4:44 pm

I knew a tri-gear would be slower -- thought I'd heard 2-3 kts....

perhaps it's time to learn to fly a taildragger...

-rh

Dokmow · Post by **Dokmow** » Thu Dec 17, 2009 5:56 pm

RobH wrote:We're looking at an MT7-235......
I'm ok with the speed 'cause it's faster than a 172 and probably gets off the runway better

You need to video tape yourself flying that plane for the first time. I want to see the expression on your face on take off.

Fun is putting it mildly

a64pilot · Post by **a64pilot** » Thu Dec 17, 2009 6:30 pm

Best I can get out of my M6 235 at optimum altitude with 8.50's is between 132 and 136 kts. I haven't figured out the 4 kt spread, just some day's it's faster than other days.

One thing, almost all other aircraft's (normally asperated) fastest speed comes in around 7500 ft, above that and you lose too much power, below that and the drag is too high.
My Maule is fastest between 9 to 11 thousand ft. I assume it's because there is so much wing.
A 182 with a STC'd 520 would be closer to the Maule, a 172 even with 180 hp just doesn't come close.
I don't know squat about the nose dragger, but that big wheel up front has to hurt more than 2 or 3 mph, I would think at least 5, also I think the factory numbers come with little tires and most people end up with tires bigger than the standard factory ones.

Wayne · Post by **Wayne** » Thu Dec 17, 2009 6:52 pm

The speed is different from plane to plane a little. My first m-7(2001) tailwheel is about 5 kts slower than the (2004) m-7 tailwheel I have now. I have 8.50's on this one and the first one. Both are 235HP and are about the same plane except the 2004 has a 3 blade prop. I think the 2004 is just set up better because its faster and just handles better.

At 3000 MSL the m-7 tailwheel (8.50 tires) cruise speed at 75% I would say is about 125 to 130 knots depending on how hot or cold the weather is.

maules.com · Post by **maules.com** » Thu Dec 17, 2009 9:58 pm

The MT7-235 IO540W on a standard 59 degF day at sealevel and standard lapse of 3.5F per 1000ft above sealevel, ie 33 deg F at 7500ft msl with full throttle which should produce 22.4 "MP if it is standard barometer of 29.92, and 2400rpm will give a true airspeed of 155mph before masses of antennae and VGs.
The M7-235B or C with IO540W on 7.00x6 tyres will give 5mph faster, with O540 B the M7 is a touch slower than the W engine.
All Maules since the M5 have elevator gap seals as standard.
Tach, MP, ASI, calibration, plus control travel adjustment and rigging will all have an effect on these performance numbers.

mxt180 · Post by **mxt180** » Fri Dec 18, 2009 9:59 am

I have an MXT-7-180, not a 235, but here's what I know: At 23 squared I'm doing 105 kias with zero flaps. At -7* I get 2-3 kias more. At 25 squared I can squeeze another 4-5 kias at 0* on the flaps. Haven't tried -7* for any length of time at 25 squared. I generally fly @ 4500' or 5500' asl here on the east coast. I only have about 105 hours on mine in mostly bluebird conditions but the indicated airspeed doesn't seem to vary much with temperature changes.

Compare that with the factory data on the 180 and you should be able to interpolate, within a few knots, a realistic expectation in the 235. I haven't flown the conventional gear but I believe the nosewheel slows you down more than just a couple of knots.

Sure, I'd like to go faster but I have no regrets.

a64pilot · Post by **a64pilot** » Fri Dec 18, 2009 10:59 am

I should have included that at around 10,000 I think I get about 18- 20" manifold? give or take and I will cruise at no higher than 2300 RPM for the approx 134 KTS. (IO-540W) Again off the top of my head, I think that is also about 11.5 GPH. Which gives me 5 hours with IFR reserve and 650 NM range, and that is at max gross weight or maybe a little more.
Not bad for a Backcountry STOL airplane.
Down low as she came from Maule and with the 8.50's she will indicate 140 kts / 160 mph with everything shoved forward.
With the 29's on it now, I just don't do that kind of thing anymore. Their adverse effect on fuel consumption and speed is almost nothing if I stay around 22 squared or less, so I just don't get in as big a hurry anymore.

RobBurson · Post by **RobBurson** » Fri Dec 18, 2009 4:11 pm

When I got my 2000 M7 235 B4B5 it had 7.00 tires. The best I could get out of it was 157 MPH GS on GPS no wind. If you want speed this is not the plane. For a STOL plane it is good.

I am now running 29X11X10 tires and my speed is now 120 ish MPH GS GPS.

iceman · Post by **iceman** » Sat Dec 19, 2009 8:24 pm

geez Rob, that's what I get with my M4-210. Do those 29's slow you down that much....flat out without trying to conserve gas I get 125-130 MPH depending on what day of the week it is...but then I'm only running 800's.

Mr. Ed · Post by **Mr. Ed** » Sat Dec 19, 2009 9:14 pm

Rob,
Upgrade to the ABW 31". That should slow you down so I can keep up with you in the MX7-180 with 8.50's.

a64pilot · Post by **a64pilot** » Sun Dec 20, 2009 2:38 pm

iceman wrote:geez Rob, that's what I get with my M4-210. Do those 29's slow you down that much....flat out without trying to conserve gas I get 125-130 MPH depending on what day of the week it is...but then I'm only running 800's.

First, I would think an M4-210 is as every bit as fast as a fast as an M7 isn't it? 25 more HP, but also lots more weight and drag? Isn't the M4-220 faster than a 7? Of course I may be wrong, but I think the M4-220 is a real hot rod.
On my 6 with the 29's, I stay slow because of the fuel burn, above about 110 kts or so the fuel burn gets to be too much.
31's are off road tires only. I think Rob, like me does a lot of pavement work, the tires Rob and I have aren't real bushwheels, but they will last forever on pavement, mine aren't "buffed" and they still show the mold line on the center of the tire after a couple of hundred landings.

jmtgt · Post by **jmtgt** » Sun Dec 20, 2009 5:12 pm

I have the same 29" tires. I get a TAS at 9500' of 136MPH. With the 8.5s I had a TAS at 9500' of 142MPH. Slowed a little but not a whole lot in my mind.

How Fast?

How Fast?

optimum altitude....?

Re: How Fast?

speed

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