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14A Thunderbolt 390-EXP119 prop?

lipper03

Builder RV14A & ZA750SD
Benefactor
Looking for prop advise on my 14A, just ordered a Thunderbolt YIO-390-EXP119. I'm confused with my options on Van's site, would like a 3 blade, just because I think they look good. Thoughts or suggestions? Posting on Facebook as well. Thanks!
 
Something to consider - 3 blades are pretty, but considerably complicate cowling removal. YMMV
 
Just installed this MTV-9 recently, love it.

2022050617540396-2522085236459514063-IMG_1800-XL.jpg
 
I was going to go with the three bladed prop but with talking with the mothership you lose 25lbs of carrying capacity in the cargo area. They look great and reduce noise at twice the cost and loss of capacity due to CG shift because they are so light.

I kept my money and my cargo.

Read form Harzell comparison of 2 vs 3.

https://hartzellprop.com/are-more-propeller-blades-better/#:~:text=In%20general%2C%20the%203-blade%20propeller%20will%20have%20a,clearance%20between%20the%20blade%20tip%20and%20the%20fuselage.
 
I was going to go with the three bladed prop but with talking with the mothership you lose 25lbs of carrying capacity in the cargo area. They look great and reduce noise at twice the cost and loss of capacity due to CG shift because they are so light.

I kept my money and my cargo.

Read form Harzell comparison of 2 vs 3.

https://hartzellprop.com/are-more-propeller-blades-better/#:~:text=In%20general%2C%20the%203-blade%20propeller%20will%20have%20a,clearance%20between%20the%20blade%20tip%20and%20the%20fuselage.

Which two blade did you go with?
 
3 blade

I went with Whirlwind 3 blade, CG is within the specified range with full baggage in the calculations. It does fall out of the allowable range for aerobatics but who does those with full baggage? (100 lbs.) Added a back-up alternator helps and the new 390EXP I believe is heavier than my 390. I even have 2 Earth-X batteries on the firewall which weight less than one standard battery. My WW 3 blade was not that much more than the Hartzell 2 blade and performs every bit as good if not better. Very smooth and quiet. W&B depends on a lot more factors than weight of your prop. I have checked my W&B twice on separate scales and intend to check again when it come back after paint. Also cowling removal is a no-brainer using the Anti-Splat fairing protector. Just slides down the protector. Vans put a 360 in one of their 14's and it's ~ 19 lbs. lighter than the 390. I'm assuming the 14 might be less tolerant to a lighter front end but that is just a guess. I'm surprised Van's would state this data without knowing the complete facts.
 
I find no more difficulty removing the cowling whether a 2 or 3 blade prop. It is not the propeller blades that get in the way, but rather the rear bulkhead on the spinner. Plenty of 2 blade RV's running around with scratched spinners and cowlings because of hastily installed/removed cowlings.
 
I had the same 'I-wanna'

I also wanted to get the 3-blade Hartzell. They look terrific!

At SnF I talked to Hatzell engineer and Sean Tucker and a few other persons.

Caveat - This is accessing my cranial data-bank as best I can.

Harzell engineer said that the engine+propeller operate as a system and that is how it should be evaluated. The lighter 3-blade composite propeller doesn't absorb the vibration and harmonics created in the engine as well as the heavier metal prop does, which has been how the system has been designed for quite a few years prior to the 3-blade composite entering the field. Hatzell testing found that rotating engine components (crank shaft, cam shaft, and the gearing in the back-side accessory case suffered fatigue and showed signs of developing failure.

Sean Tucker asked me, when I posed the question of which propeller should I consider, "Do you plan to do regular competition aerobatics?" He said that if I wanted to regularly execute full power straight up maneuvers I should go for the 3-blade composite, that is what it did best. BTW, I have heard more than one report that he disassembles his show plane completely every year (engine and airframe) to do a thorough inspection. Plus the 3-blade composite was just under double the price of the metal 2-blade, plus the spinner was $1,400 - 4 years ago. I am very pleased with the 2-blade metal, 74" diam, constant-speed, HC-C2YR-1BFP/F7497 PROP.
 
BTW, I have heard more than one report that he disassembles his show plane completely every year (engine and airframe) to do a thorough inspection.

His team posted a time-lapse video several years ago showing them disassembling and reassembling his biplane for one of it's yearly teardowns. Cool vid, but can't find it now.
 
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I went with Whirlwind 3 blade, CG is within the specified range with full baggage in the calculations. <snip> I have checked my W&B twice on separate scales and intend to check again when it come back after paint.

Paint will move the empty CG aft, and burning fuel also moves the CG aft. I haven't seen a W&B spreadsheet for a painted RV-14A with a composite prop that is still within the aft CG limit when you have 100 lbs of baggage, two adults, and have burned fuel down to ~8-10 gal. Would be interested in seeing your final numbers once you get it back from paint.
 
ordered 3 blade MT-12-B/188/59f

I ordered the MT-12-B/188-59f today after a few questions and pro/cons from Kevin in van's tech support. Excited!
 
I ordered the MT-12-B/188-59f today after a few questions and pro/cons from Kevin in van's tech support. Excited!

You may want to talk to the folks at McFarlane about your choice (plus I think they can offer a better price than Van's).
No restriction on the MTV-9, probably less maintenance due to the heavy duty hub, ok with EI and higher compression.
I personally chose the -9 to run on my IO-370.

• MTV-9 Heavy-Duty 3-blade hub is recommended over the MTV-12 series for use on engines without counter-weights,
and for engines with 'more than stock output'
• MTV-12-B/183b Medium-Duty hub is limited for use on engines with factory timing, standard compression and 6th
order dampened crankshafts - it may also require restricted RPM operation ranges.
 
Well that’s why I was asking vans, they didn’t say there was a restriction or limitation, McFarland can confirm that?

You may want to talk to the folks at McFarlane about your choice (plus I think they can offer a better price than Van's).
No restriction on the MTV-9, probably less maintenance due to the heavy duty hub, ok with EI and higher compression.
I personally chose the -9 to run on my IO-370.

• MTV-9 Heavy-Duty 3-blade hub is recommended over the MTV-12 series for use on engines without counter-weights,
and for engines with 'more than stock output'
• MTV-12-B/183b Medium-Duty hub is limited for use on engines with factory timing, standard compression and 6th
order dampened crankshafts - it may also require restricted RPM operation ranges.
 
Well that’s why I was asking vans, they didn’t say there was a restriction or limitation, McFarland can confirm that?

Suggest you reach out to McFarlane prop guys (very experienced with MT) or MT itself for more info.

Note the warning on Van's page (not approved for EI):

WARNING: Damage or excessive wear to the engine or propeller may occur if electronic ignition systems are used and timing is
set to a value other than the fixed timing stated by the manufacture (for Lycoming this is labeled on the engine dataplate).4-cylinder
engines 195hp and above must include 6th order crankshaft counterweights and operate within the engine manufacture's timing specifications if electronic ignitions are installed when using the following propellers MTV-12, MTV-15, MTV-18, MTV-20 and MT 185. Lycomings electronic ignition system (EIS) for both standard timing (matching the fixed timing used previously on Slick magnetos') and the advanced timing curve are allowed for use with the following propellers MTV-12, MTV-15, MTV-18, MTV-20 and MT 185. MTV-9-B/183-50a propeller must be used with 4-cylinder engines 195hp and above if 6th order crankshaft counterweights are not installed or electronic ignitions are installed that are operated outside the engine manufactures timing specifications.

The -9 hub was made for higher HP engines, thus handles more 'abuse' without strain (=lower mntc costs).

See this thread for discussion on this subject:
https://vansairforce.net/community/archive/index.php/t-192407.html

Type certificate data sheets for MT can be found here:
https://www.mt-propeller.com/en/entw/pro_hydr.htm

Maximum Continuous Power @2700:
-12 = 300, 44 lbs
-9 = 421, 53 lbs
 
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Thanks Walt, I'll ask McFarland, now that I'm freaking out!

No need to freak out, lots of folks use the -12, the cost for the -9 is 'only' about 1k more, to me it was worth it.
If you plan on ever running Pmags or any other EI then the -12 is not recommended.
 
Running Hartzell 3 blade composite- no CG issues

I have an exp119 WITH accessory case. So a bit heavier than the normal-119. In fact when I’m solo I put ballast in the luggage area. Otherwise I can’t get a nice flare on landing. My CG stays within limits under all scenarios assuming gross weight is observed.
 
I did get a change to talk to Larry at McFarland today, and both 9 and 12 are acceptable. The 12 does have a shorter recommenced TBO and may see bearing wear more then a 9, but no safety of flight or RPM or other limitations for an RV14A with a EXP119. I'm checking back with Vans to make sure I understand the color options and delivery assembly vs ordering with McFarland. Thanks Walt for the suggestion!
 
I did get a change to talk to Larry at McFarland today, and both 9 and 12 are acceptable. The 12 does have a shorter recommenced TBO and may see bearing wear more then a 9, but no safety of flight or RPM or other limitations for an RV14A with a EXP119. I'm checking back with Vans to make sure I understand the color options and delivery assembly vs ordering with McFarland. Thanks Walt for the suggestion!

Don’t forget the PMAG limitation with the -12, and the extra weight of the -9 would help with CG.
 
Composite 3 blade

I’m not sure who started the “if you go composite blade route you will be aft heavy on the 14” but seems a myth. Vans designed the 14 with a 360 and that weighs 18 lbs less than the original IO390. I don’t know what the EXP 390 weighs but as one builder points out adding an accessory case increases the weight. Not to mention adding a stand-by alternator. My best landings are made when I have my bicycles in the baggage area and tools. Check your W@B calculations assuming different prop combinations.
 
Please review

Just did my W&B and inserted loads that would shift CG furthest aft. Let me know if you see any errors.
 

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Please review

Finished W&B after paint. Let me know if anyone sees an issue. Of course I can't fly acro but why would I with baggage (And my wife on board)
 

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