All-

Here's a video to show the impact on cruise speeds of various modifications. My airplane. The first run was a baseline airplane as I bought it. The second was after the airframe was gone through and the airplane lost weight. Then there were two runs with the MT 2 Blade prop. Then a run with WingX added and finally a run with a brand new Pponk engine installed.

All runs were made about 2300 lb, at 24/2450 and LOP power settings for consistency. I still have the Vgs to do for the wing- I'll do wing performance and cruise speed testing for that. Also, I'll do it when I install the big tires. Promises, promises. At some point I'll redo the takeoff/land performance testing as well.

gunny

Enjoy:

Beautifully detailed work! Awesome, and thanks!

Fantastic, very well done! Thank you for taking the time to make this video.

Kurt

Thanks ya'll. I appreciate your comments!

gunny

Posted on YT but finally joined here and thought I'd pass along another thanks. Awesome plane!

Thanks for doing the testing! I'm a data geek, could you post the graphs here so they're easier to read? Thanks!

1:1 Scale wrote:Thanks for doing the testing! I'm a data geek, could you post the graphs here so they're easier to read? Thanks!

Sure, here it is.

gunny

Are all the velocity numbers on your graph in MPH?
Thank you,
pat

Gunny wrote:…... I still have the Vgs to do for the wing- I'll do wing performance and cruise speed testing for that. Also, I'll do it when I install the big tires. Promises, promises. At some point I'll redo the takeoff/land performance testing as well. ....

I thought you posted your 180 for sale-- I guess you reconsidered?
Glad to hear that, that's a nice airplane,
and I think you'd have yourself a pretty bad case of seller's remorse if you did get rid of it.

iPat wrote:Are all the velocity numbers on your graph in MPH?
Thank you,
pat

It is MPH.

gunny

The 120-130mph baseline seems awfully low, must be the lean of peak? My 180 at 23/2300 at 6000 would run 150-160mph true pretty readily with 470, 88" prop, and 850's. Didn't realize running LOP reduced it that much. The delta from the MT looks very attractive regardless.

asa wrote:The 120-130mph baseline seems awfully low, must be the lean of peak? My 180 at 23/2300 at 6000 would run 150-160mph true pretty readily with 470, 88" prop, and 850's. Didn't realize running LOP reduced it that much. The delta from the MT looks very attractive regardless.

I think I said that in the video. All power settings the same and LOP. The MT performance is impressive.

gunny

FWIW... The pre-mod numbers seem slow for a stock 180 as book numbers should be a bit higher.

One great lesson I was taught was this: Book is book... If a bird does not do book, one should dig and find the reason. Over the past year I have inspected many Cessna TGs. If I fly the bird and it seems slow (and I cant account for the drag) I first think rigging. If its rigged correctly, then its usually a sign of past damage. Lots of times you can see telltale signs of this evidence where past mechs have tried to fix it. eccentrics are not even, flaps are not in the correct position, or even tabs on ailerons. I have found this a bunch. When you start to explain it to the owner, they often argue and say how nice the bird flies.... "hands off" they say.

I would first start by measuring the bird. A lot can be said for making sure wash is correct, flap rods are the correct length, ailerons are in the correct position, and that the wings are square. If the bird looks square, then I would re-rig her. Perhaps you could pick up a tick or two?

My wagon was slow. With 29s, bubbles, ski brackets, handles, antennas, BBW, etc, it was draggy, but the speed was too slow to account for those items. It had some small previous damage, but the bird is perfectly square. I properly re-rigged the bird, and picked up 11 mph. After that, everything aligned with what I would have expected.

At any rate, thanks Scott for posting the vid. It is really helpful to all of us, and a great resource. Take my armchair QBing with a grain of salt... Its hard to know anything really w/out being there.

On a side note: I tend to agree RE: the MT. Its a really great mod for sure. (I actually think that the 2 blade is where its at. My feelings are this: 2 blade is best all around. 3 blade is for ego. LOL. Unfortunately on my bird, I failed the second point.)

My 2 cents. The speed increment for the MT-2 blade is certainly impressive in comparison to the P-Ponk; similar increase in speed for less than 1/2 the price. When I went to the P-Ponk, I had to change props. I went for the Hartzell C58 88” as opposed to the MT, ’cause I found a low-time oil-filled pristine one for $2K. I ended up with several months of down time waiting for the field approval. At that time, I think the MT went for maybe $14K. Perhaps penny-wise, but dollar foolish. All that wasted flying! I’ll upgrade to the MT when the Hartzell goes, and improve my cg and useful load, too. Great work, Gunny!

Since my 180A has a Pponk engine and a 2 blade MT, how valid are book cruise speeds? On a trip from AK to lower 48 and back, with 8.50s, double puck brakes, ski tabs, handles, and power at 20 inches and 2300 rpm, I typically saw 138-140 mph at 5000 or so DA.

Bigrenna wrote:.........….My wagon was slow. With 29s, bubbles, ski brackets, handles, antennas, BBW, etc, it was draggy, but the speed was too slow to account for those items. It had some small previous damage, but the bird is perfectly square. I properly re-rigged the bird, and picked up 11 mph. After that, everything aligned with what I would have expected.....

11 mph--wow! That's a helluva improvement.

Excellent info Gunny, thanks a bunch!

I am new in this fórum and you all must have evaluated the pros and cons of putting VG´s.
Do you realy need them to pay off for the 2 Kts or what ever the loss of speed is?