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What actual cruise speeds IAS do you get on your P2004 Bravo?


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got ours two months ago, and preponderance of evidence is our Rotax 912 100 hp is not turning out full rated power. (Compression on the low side, other evidence, etc.)

 

So you could say thus is a sort of a real world poll/survey to get a sense of how about how short of a fulldeck we're playing with.

 

At wide open throttle in level flight and medium load ...one light pilot and half full tanks..we get about 5350 rpm and maybe 110 knots or 105 knots IAS.

 

Sure it varies a bit with temperatures and altitude.

 

If i back off throttle and cruise at 5000 IIRR cruise is about 100 knots.

 

I've heard reports that most P2004 Bravo's will actually cruise faster than the factory claim of 116 knots at 5500 rpm.

 

Alex

 

P.S., FWIW we recently had carbs rebuilt and synced, new plugs, oil change, and that did help. Before that our numbers were even slower.

 

Our primary suspect from the last leak down compression test is that the intake valves are a bit leaky..possibly some lead deposits from last owner,s use of avgas.

 

Disappointing as we purchased the plane with only 300 hous on it.

 

Seems likely if we want to come up to full power we may be looking at an expensive valve job.

 

 

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Have you had a leak down test done? That will tell you where it's down.

 

I recently replaced rings in one cylinder due to owner using fuel a few months old.

 

Pitot system leak check?

 

Should be a bit quicker than that.

 

What prop have you got?

 

 

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Prop could be a bit too coarse? (If it's adjustable) Should be pulling at least 5600, WOT, flat, level.

 

A higher/hotter climate than previously used may mean it needs adjusting.

 

 

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Prop could be a bit too coarse? (If it's adjustable) Should be pulling at least 5600, WOT, flat, level.A higher/hotter climate than previously used may mean it needs adjusting.

Yeah, prop was our first suspect. But not guilty. It's fixed pitch, and is confirmed to be the correct standard factory prop.

 

Yes, it SHOULD be pulling 5600 WOT. That it's not is one of several indications that our 912 isn't putting out the full rated 100HP.

 

 

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Have you had a leak down test done? That will tell you where it's down.I recently replaced rings in one cylinder due to owner using fuel a few months old.

Pitot system leak check?

 

Should be a bit quicker than that.

 

What prop have you got?

I mentioned in first post in this thread that we already had a leakdown test. It reveals that there is some leakage at the intake valves.

 

Re prop: It's fixed pitch, and is confirmed to be the correct standard factory prop. Since these props aren't absolutely dead on identical it's slightly possible that it's pitch a tiny bit high. But if that were all that's going on (pitched a bit high) what we should see it at WOT level flight slightly lower than standard RPM but actually slightly HIGHER than standard cruise speeds.

 

That's the way a pilot would use an inflight adjustable pitch prop: Pitch low for climb, but once up and level increase pitch a bit for better cruise speed and economy.

 

Now I DO like your idea that we could have a IAS that's under-reporting our speed due to a pitot system leak, or whatever.

 

Would be nice to discover that. Will check. But pretty darn sure it's not under-reporting our airspeed.

 

The fact that we can't hit normal expected RPM on WOT level flight, don't climb quite as well as expected, have compressions on the lowish end, all point to an engine not quite putting out expected power at top end of it's power range.

 

 

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What altitude are you doing those tests at? Also what sort of ambient temps? Oregon comes up on google as being 3000 feet amsl with highest point 11000 feet amsl so if you were above 5000 feet with a hot day that would reduce the power as well. (Maybe! I'm not an expert in these things)

 

 

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"What altitude are you doing those tests at? Also what sort of ambient temps?" SDQDI asked.

 

--------------------------------------------------------------------------------

 

It's true that altitude and temp make a difference, but we're significantly further off "expected" that it's clear we're not cranking out full power, regardless.

 

FWIW, The numbers I reported were typically at altitudes between 4000 and 8000 feet MSL temp between 50 and 80 F. If anything at the higher altitudes and higher temps we should have seen WOT even higher than the official 5600.

 

There's no really question we're not getting full power. I appreciate all the diagnostic suggestions, but that's pretty much a closed case.

 

I was mainly hoping some Tecnam P2004 Bravo flyers might post their max IAS WOT and maybe their typical IAS at 5500 or 5000.

 

Just get a feel for how short of expected we really are in real world terms.

 

 

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The leak down test done, what are the figures? If it's down there is no question but to fix it. Pretty easy to work on really.

 

Sorry I can't help with speeds, I don't fly the aeroplane, just maintain it.

 

 

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Our experience with the Bravo and other Tecnams, is that the GT Tonini wooden prop, kills both cruise and take-off performance.

 

Three composite blades, with in flight pitch control, makes for a frightening improvement.

 

Frightening? Well....when you have to tell the handling pilot to slow down for structural reasons.....

 

 

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85kts @ 4800 rpm with GT prop. Taken from my photo which also shows 4,500 AMSL with nil climb/descend and hands off stick. One up, 80 litre fuel load.

 

I would post photo but this site can't handle the data.

 

 

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If anything at the higher altitudes and higher temps we should have seen WOT even higher than the official 5600.

Right........been flying long.......

 

 

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Sky ranger those temps are nice and cool and won't affect things much but at 8000feet amsl you won't get anywhere near 100hp.

 

If you had the leakdown numbers there would be quite a few here who could give better advice than me but just keep in mind just how much difference altitude makes.

 

 

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Our experience with the Bravo and other Tecnams, is that the GT Tonini wooden prop, kills both cruise and take-off performance.Three composite blades, with in flight pitch control, makes for a frightening improvement.

Frightening? Well....when you have to tell the handling pilot to slow down for structural reasons.....

Nong is right on the money - we have a P2004 Bravo on the field - he gets 115-120kts cruise with an Airmaster constant-speed prop - and just as important - great climb rate at the full 5800 rpm and the ability on full fine to come in to short strips at a steep angle of descent without gaining excessive speed. The owner couldn't believe the difference when he fitted the Airmaster. Not cheap (around NZ$10,000 all up?) but well worth it in his view.

 

 

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85kts @ 4800 rpm with GT prop. Taken from my photo which also shows 4,500 AMSL with nil climb/descend and hands off stick. One up, 80 litre fuel load.I would post photo but this site can't handle the data.

Hi Nong

What I do for large MB images is select them on my computer, go to the left and select email image; this reduces the size automaticly and places in an unaddressed email. I then copy this size email attachment and place it on my computer in my reduced images folder and save. Then do the upload file on this site from the reduced image file. Hope this helps you post images.

 

Regrds

 

Mike

 

 

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Nong is right on the money - we have a P2004 Bravo on the field - he gets 115-120kts cruise with an Airmaster constant-speed prop - and just as important - great climb rate at the full 5800 rpm and the ability on full fine to come in to short strips at a steep angle of descent without gaining excessive speed. The owner couldn't believe the difference when he fitted the Airmaster. Not cheap (around NZ$10,000 all up?) but well worth it in his view.

So would I be correct in that the problem is people tend to quote the constant speed prop/best case scenario cruise speed when selling the finer points of an aeroplane?

 

 

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Well obviously if the aircraft is equipped with a constant-speed prop and that produces enhanced performance you would naturally advertise it as such!

 

 

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Well obviously if the aircraft is equipped with a constant-speed prop and that produces enhanced performance you would naturally advertise it as such!

If it is a standard feature of that aircraft yes. I am saying that does not always seem the case.

 

 

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85kts @ 4800 rpm with GT prop. Taken from my photo which also shows 4,500 AMSL with nil climb/descend and hands off stick. One up, 80 litre fuel load.I would post photo but this site can't handle the data.

Hmmmm. That's IIRR, darn close to what I get at 4800. I may even get faster.

 

Today near sea level at about 70 Fahrenheit I tried WOT level flight pilot plus passenger both mid weight (15o pounds each ) plus 20 kilos baggage and half full fuel.

 

Got about 5200 rpm at 110 knots IAS.

 

So maybe we're not so far out of the ballpark?

 

But on the other hand here's the thing:

 

I was watching a YouTube video of a show-off technam bravo flight.

 

During part of the flight at what was clearly something over 6000 feet the camera happened to pan over the instrument panel and I saw 128 IAS knots at something like 5500 rpm.

 

Maybe they had a non standard prop ?

 

Alex

 

 

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The leak down test done, what are the figures? If it's down there is no question but to fix it. Pretty easy to work on really.Sorry I can't help with speeds, I don't fly the aeroplane, just maintain it.

Here's the complete compression history from logbook:

 

Most relevant is most recent.

 

:

 

First number is the number or hours on engine at time.

 

Next five numbers in a row are cyclinder 1, 2, 3, 4 in that order

 

4//28/07

 

53.6hr 76/80 75/80 76/80 76/80

 

4/22/08

 

114 hr 72 72 73 72 not clear what knd of compression test this was. Maybe not leakdown test?

 

4/22/09

 

150hr 86/87 86/87 86/87 86/87

 

5/25/12

 

239 hr 74/87 72/87 78/87 75/87 This appears to have been done at a reputable place.

 

6/03/13

 

258 hr 75/82? 78/87 80/87 82/87 Done at same facility, same iRMT, as above. 82 on first probably a typo6/2/14

 

6/03/14

 

285 hr 80/87 74/87 78/87 76/87 Same facility, same iRMT, as above.

 

5/11/15

 

302 hr 83/87 81/87 83/87 83/87 Quality of the guy

 

doing this annual questionalbe. Test done on COLD engine.

 

6/03/15

 

317 hr 74/80 74/80 75/80 76/80 Note this was by a mechanic who is Rita's skilled but

 

who used 80psi, not 87 as start . leakage was clearly most,y on the intake valve side ..leak thru carbs.

 

Note that static RPM is now 4900 RPM almost up to factory static RPM test, which was is 4950.

 

Since carb rebuild, carb sync, plug change, and running declain

 

deleading additive between 317 hours and today (about 380 hours),

 

the following changes and differences.

 

The WOT level flight RPM has increased from 5000 to about 5400 ... still

 

below the 5600 from the factory flight tests.

 

The WOT level flight IAS before Shawn's work before 317 hours was 100 knots at ~5000 RPM.

 

After that 317hr work and some hours WOT max level flight IAS it is

 

currently ~110 (or at most 115)knots at 5400 RPM

 

The original factory max level flight recorded test IAS was 132 knots IAS at 5600 RPM. Near sea level

 

 

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Our experience with the Bravo and other Tecnams, is that the GT Tonini wooden prop, kills both cruise and take-off performance.Three composite blades, with in flight pitch control, makes for a frightening improvement.

Frightening? Well....when you have to tell the handling pilot to slow down for structural reasons.....

In the USA a major the selling point of the Tecnams (and many similar air craft is they fall in the definition of "light Sport aircraft" LSA?...which is a tad easier to get licensed for than the standard USA private pilot's license. That definition explicitly excludes use of any in-flight-adjustable pitch prop.

 

Based on what you write one , or even a different fixed pitch prop, could be a real step up on cruise. Maybe.

 

But one thing doesn't compute in trying to blame totally on my slower than advertised cruise on the factory prop: I had an a grojnd adjustable prop on my previous rota powered LSA. When I deliberately set its pitch a bit _higher_ than official rotax guideline/wisdom...which is "set pitch such that at WOT level you get 5800 rpm".... I got a HIGHER cruise speed (at the cost of giving up a bit of climb rate and short field take off ability.)

 

There are some good props for the rotax (I particularly like the IVO..very fast and easy to change pitch) but not at all sure Tecnam would issue a letter of authorization for that.

 

BTW: Come to think of it... somewhere I saw something about an OPTIONAL Tecan approved prop. Also fixed pitch???

 

Anyone know anything about that?

 

Alex

 

 

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Skyranger2

 

My Tecnam Sierra runs a Hoffman glass over timber fixed pitch prop, very quiet, 4800 rpm which I normally cruise at sees me getting between 95 and 98kts IAS S&L

 

Full power climb on a standard type day 1 up & full fuel see's me pulling 5200 rpm on climb at 75kts IAS and anywhere from 800 to 1000fpm

 

This prop was standard with the aircraft

 

Cheers

 

Alf

 

 

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Yesterday took brutus Bravo to 2000 feet - OAT would have been 25 degrees - 150 kilos of pilot and fuel - no wheel fairings - standard timber prop

 

flew one way - then reciprocal back - it was a lumpy day and suspect plane was in lift and then sink .......... not the best day for record taking

 

rough recording was as follows - speeds were (REVs: IAS / GPS)

 

OUTWARD

 

5000: 103 / 95

 

5200: 104 / 94

 

5400: 119 / 110

 

INWARD

 

5000: 103 / 105

 

5200: 104 / 110

 

5400: 110 / 114

 

5600: 115 / 118

 

 

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