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MT vs Hartzell Flight Differences

Champ

Well Known Member
I plan on replacing my Hartzell HC-C2YR-1BFP/F7497-2 (Blended Airfoil for short) with an MTV-9-B/183-50a (3 blade) next weekend and was wondering what flight differences to expect.

1. Will it need quicker and more right rudder on take off?
2. Will it slow down quicker with throttle reduction?
3. If I get slow in the flair will my RV-8 sink more and need more throttle to keep it from bouncing?
4. The MT is about 5 lb lighter than the Hartzell, probably with less inertia. Will start up be any different?
5. Any other flight characteristics that might change? Especially thinks to look out for on first flight.
6. I have 232 hrs tach time/293 Hobbs on the Hartzell. The alternator belt looks good but would it be a good idea to replace it while the prop is off? I have a new belt just in case.
7. I'm not aerobatic or formation current yet but wonder how the MT might change these.

Here's the MT. It will probably look better on the plane:
MT.jpg



I expect better take off and climb performance but loss of a few knots in cruise. Time will tell.
 
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I expect better take off and climb performance but loss of a few knots in cruise. Time will tell.
There were some tests run a few years ago and this is what seemed to be the consensus. I don't recall if the two props tested were these exact models, or if those props have changed over the years.

One thing to take into account is that you might need some adjustment on the prop controller or the prop fine pitch stop. Carefully check the MT manuals to see how to do this if you have not done it before. I'd also be prepared for a prop overspeed during your first takeoff, since ground running is not an exact simulation of flight for the prop, obviously.

Also, be ready for a more challenging time removing and replacing the cowl - perhaps lots of painter's tape and a helper the first few times.

Not sure where you hangar, but take care about hangar rash on the prop - one of my hangar mates has a similar prop, and it got nicked by the towbar - a chip came off of the thin trailing edge. You might consider some of those rubbery prop covers. Thankfully the repairs on the MT are not that difficult as documented in the manual - I've never done one myself, but looks "easy".
 
Boring reminder - Hope you remember to call TC with updated equipment listing & W&B report as it affects your CofA.

Looking forward to a report on performance changes & how the 5 pounds off the nose affects your solo CofG feel & handling characteristics.
 
Ralph - Thanks for the TC reminder. My RV is nose heavy solo even with the battery in the back. I keep my tool and tie down kits (18lbs) on the baggage shelf to help the CG. 5 lbs off the nose should be nice.

I did a couple of speed runs on the Hartzell to give me something to compare the MT to: 7500 ft, WOT, 23.1"MP, 2400 RPM, 77% Pwr, 15.5 GPH, Full Rich, 7deg OAT and got 173-175 knots.

I'll report on the MT performance.
 
MT

Almost every MT prop ends up back to them for some sort of repairs…… big box and big bucks to ship a 3 blade prop .
I’d go for a 2 blade Whirlwind if you are looking at saving weight.
 
Flew a back to back with my Rocket and a buddy's F-1 looking for this exact comparison. My 2 blade BA made more thrust at 2700 than his 3 blade MT. At approximately the same weight, I accelerated faster, had better climb, and could almost stay with him at top speed using 2700 (which is saying something, because his airplane is FAST). But at 2300 cruise, he handily walked away.

Keep in mind this is an 80 inch Rocket specific BA Hartzel, so may not be the same as the smaller 4 banger version you have.
 
I plan on replacing my Hartzell HC-C2YR-1BFP/F7497-2 (Blended Airfoil for short) with an MT-9-B/183-50a (3 blade) next weekend and was wondering what flight differences to expect.

1. Will it need quicker and more right rudder on take off?
2. Will it slow down quicker with throttle reduction?
3. If I get slow in the flair will my RV-8 sink more and need more throttle to keep it from bouncing?
4. The MT is about 5 lb lighter than the Hartzell, probably with less inertia. Will start up be any different?
5. Any other flight characteristics that might change? Especially thinks to look out for on first flight.
6. I have 232 hrs tach time/293 Hobbs on the Hartzell. The alternator belt looks good but would it be a good idea to replace it while the prop is off? I have a new belt just in case.
7. I'm not aerobatic or formation current yet but wonder how the MT might change these.

Here's the MT. It will probably look better on the plane:
View attachment 13933



I expect better take off and climb performance but loss of a few knots in cruise. Time will tell.

Changing your prop is considered a MAJOR CHANGE.... so you will be going back into phase 1. You will be able to answer all of your above questions.
 
Prop Change

Changing your prop is considered a MAJOR CHANGE.... so you will be going back into phase 1. You will be able to answer all of your above questions.

Generally(in the US) changing from one constant speed to another constant speed or fixed pitch to fixed pitch is NOT considered a major change with the caveat that a significant change in weight and balance could be considered a major change.

Skylor
 
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Th OP is in Canada, are they required to go back to phase 1?

For the most part engine, prop or fuel system changes are considered Major Changes in Canada. As they are listed by model & sn# for the CofA, changes have to be reported. TC may require a test period in which they suspend your current CofA and issue a temporary Flight Permit so you can flight test your modifications. When complete, you present your test results & TC re-issue your CofA. Pretty easy process.
 
My current prop is on Transport Canada's data base as it was provided to them on the initial application for a CofA and the Climb Test Report submitted with it. The prop also appears on the annual AAIR (Annual Airworthiness Information Report).

So yes TC needs to be advised. This is spelled out in CAR Part V - Standard 571 Appendix L. I'll see if TC requires a test period (Phase 1 in America) when I submit the form.

I was advised that failure to do this could invalidate hull insurance coverage.

Thanks to all for the input.
 
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If anybody is inclined to help pull your AC by the blade roots make sure they take their rings off as even a smooth ring can apply more pressure to the trailing edge than it can support, causing small pieces to chip out. Can be a bit of a test of a relationship. Do you love your wife or your new MT?

A good briefing and awareness will prevent problems.
 
Talked to a really helpful guy at TC today. He said it’s enough to submit a “Major Repair or Major Modification Report” so TC can update it’s database but no formal flight test period is required.

It seems this is one area where Canada is less regulated than the US. We only have a 25 hr initial flight test period and I think our Operating Conditions are less rigorous - my OC only says “VFR Only” and “Aerobatic Flight Prohibited”.
 
Replaced my Hartzell BA yesterday with the MT. Flew it today. Here are the questions asked in my first post and initial observations:
1. Will it need quicker and more right rudder on take off? Seems to take more right rudder on take off and climb.
2. Will it slow down quicker with throttle reduction? Didn't notice any difference.
3. If I get slow in the flair will my RV-8 sink more and need more throttle to keep it from bouncing? About the same.
4. The MT is about 5 lb lighter than the Hartzell, probably with less inertia. Will start up be any different? MT is actually 7 lb lighter and has shifted the empty CG back 9/16". Start rotation seems quicker and stop on ICO is instant.
5. Any other flight characteristics that might change? Especially thinks to look out for on first flight. More right rudder.
6. I have 232 hrs tach time/293 Hobbs on the Hartzell. The alternator belt looks good but would it be a good idea to replace it while the prop is off? I have a new belt just in case. Forgot to do this.
7. I'm not aerobatic or formation current yet but wonder how the MT might change these. Still wonder about this.

Also:
1. My Hartzell turned up to 2710 rpm on take off. MT hit 2680. Would it help to adjust it to 2700? Would this be done on the governor or low pitch stop on the prop?
2. Climb with the Hartzell was very good, MT seems even better. 2500 fpm +-.
3. Vibration is about the same. Hartzell was never dynamically balanced but was pretty smooth to.
4. Did a short speed run and got 169K at 7500 ft, WOT, full rich, 2400 rpm, 23.0" MP, 77% pwr, 6C. So - maybe 4K slower than the Hartzell. Need to do more rigorous flight test to verify this.
5. Did some stalls, slow flight, lazy eights and didn't notice any difference. Plane flys the same.
6. I'll be doing more flight tests to verify and add data.

Here's the MT on the RV:
RV with MT.jpg
 
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Prop Change

My DAR who is ex FSDO spent some time on this and was very specific. Fixed pitch to fixed pitch, not a major change. No return to Phase one required. Fixed pitch to Constant Speed is major change, usually five hours in phase one. There are way too many people including FSDO and DAR's who do not understand this. For much of the early history of EAB there was no requirement of any kind for prop changes.
I tried at least six different props on my EAB in the 60's.
 
My DAR who is ex FSDO spent some time on this and was very specific. Fixed pitch to fixed pitch, not a major change. No return to Phase one required. Fixed pitch to Constant Speed is major change, usually five hours in phase one. There are way too many people including FSDO and DAR's who do not understand this.

When I had my Baby Lakes Biplane, I had this question and got the same answer that your guy is saying.. Fixed pitch 2 blade to fixed pitch 2 blade.. no major change. What does your guy say about fixed pitch metal to a lightweight wood prop?
 
Don,

Thought I would keep the Hartzell for about a month and make sure I was happy with the MT. So far I like it a lot. The Hartzell will show up on VAF classifieds then. Maybe I’ll hang it over the fireplace in the mean time.
 
I have the same combo, not flying yet but I appreciate your report, thanks.


Dennis, you will need to change your signature... ;)
 
Replaced my Hartzell BA yesterday with the MT. Flew it today. Here are the questions asked in my first post and initial observations:

1. My Hartzell turned up to 2710 rpm on take off. MT hit 2680. Would it help to adjust it to 2700? Would this be done on the governor or low pitch stop on the prop?
View attachment 14276

I found it took some careful reading of the MT prop and governor manuals,
Also this advice from a related post;
Follow the approved data, of course - the manual. Generally, set the gov for 2700. Then set the low angle (prop hard stop) adj to pull the RPM down a tad to, say 2675. That will give full takeoff RPM after a few feet of roll and the best power off glide for the prop if the prop control is full forward. It will also reduce overspeed in case of rapid throttle movement.
 
1. Adjusted my Hartzell governor to get 2700 RPM on the MT on take off like the Hartzell BA. TO roll seems about the same.
2. After a speed check on the MT under the same conditions as the Hartzell (7500 ft, 2400 RPM, WOT, full rich, 23"MP, 77% pwr, 5deg OAT) the MT is 4Kt slower 170Kt vs 174 on the Hartzell. Pretty much as expected.
3. The MT slows me down a lot quicker than the Hartzell. This is especially noticeable in the pattern, turning downwind to base to final. Have to be more careful about keeping the airspeed up and get used to flying a tighter pattern (in case of engine loss). Glide ratio is reduced. I'll have to do some glide tests to verify the numbers.
 
3. The MT slows me down a lot quicker than the Hartzell. This is especially noticeable in the pattern, turning downwind to base to final. Have to be more careful about keeping the airspeed up and get used to flying a tighter pattern (in case of engine loss). Glide ratio is reduced. I'll have to do some glide tests to verify the numbers.

Have you adjusted the hard stop in the hub yet? Mine came with the hard stop set too fine. Your pattern sounds just like mine, I had to use 2000 or more rpm to keep 85mph. Though setting the governor controlled the takeoff RPM fine pitch, the hub nut controls the glide fine pitch. One turn tighter on the nut reduces 400 rpm, takes some adjustments and test flights to find the sweet spot to match the hard stop to just reduce the rpm slightly below 2700 until you’re rolling.
I had to buy two wrenches to fit these large double nuts, then grind one thinner to fit on the back nut without jamming the front lock nut.
But if you have done all this then what you are experiencing is just the greater braking power of the three blades.
Cheers!
 
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We operate a 7 with an IO-360 and MT 3 blade prop. 10 years, 600 hours, 1 low use overhaul on calendar life at 6 years - cost $1500US.

Would I use another prop - No !

The MT is super smooth, accelerates and decelerates superbly, does aeros and formation exquisitely and saves weight - important on the 8. I fly and help look after an 8A with an angle valve motor and Hartzell metal prop - it needs 12lbs of lead bolted onto the stern post to get into balance :(

One thing to experiment with is on approach - don't go to full fine, land at 2300 or 2400 set, you will get sweeter touchdowns as the prop is not disking as much. I would only land full fine on under 1200' strips.

The bottom cowl comes off and goes on easy with the 3rd blade vertical - no issues at all with clearance, you just have to play with the angles.

Leave the prop governor alone, your take off rpm is fine.

Enjoy the prop !

Oh..... and it looks super cool :D
 
Go around?

We operate a 7 with an IO-360 and MT 3 blade prop.

One thing to experiment with is on approach - don't go to full fine, land at 2300 or 2400
Hi Mike, on top of the killer looks, I confirm that the bottom cowl is easy to remove/install with the MT. I do it alone with help from a padded stool.

I did hear/read a few times now of suggestions to approach for landing at 2400ish RPM to avoid too much braking from the prop and smoother flaring.
With 200 hp, I presume that in case of go-around, it will not be difficult to climb even at 2300-2400 RPM...unless there's an obstacle in front..

What about excessive over-squaring? One must then not forget to increase RPM before throttle?? Or you're not too concerned about it for a short time only???
 
I agree bottom cowl removal is no big deal with the MT. I use one of those rolling hospital patient tables that crank up & down with a padded wood structure on top to match the slope of the cowl. Clock the prop for the biggest bottom gap, roll it in, raise it up, roll it out.

I’ll give the 2300-2400 rpm approaches a try. Climb out in a go around at this rpm is still pretty good but can always push the prop control to 2700 rpm.
 
Something I noticed while ferrying a -7 with the 3 blade MT prop, cruise speed was virtually unchanged at rpms from 2700, down to 2200 rpm. The difference was that at 2200 rpm, I was able to lean it much more. This was at 11,500 or more where the MP was 15 to 18 inches or so.
 
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