Alpha40 special prop
 

Hi,
Is the special trainer 3-blade prop that comes with the Alpha40 a 10.5x4? The manual for the version of Alpha40 that comes with the prop doesn't say what size it is.

Thanks

RE: Alpha40 special prop
 

It's that or 10.5 x 3.5 . I called Horizon several years ago and asked. It is not a really typical prop. I bought several, but haven't ever used any. They are still in the bags. I went to an 11x5,6, and 7. The 5 and 6 are my favorites on that plane.

RE: Alpha40 special prop
 

Grab a 10x6 and throw her on

The engine on the rtf trainer likes to turn rpms don't load it down to much with something like an 11x7. with a 10x6 you get about 14 400 rpm on the ground when broken in and the engines is very happy and performance is very nice...


Steven

RE: Alpha40 special prop
 

Thanks for replies.

I have the ARF not the RTF, but I ordered separately an Evo trainer prop. My engine is a TT Pro 46. It's broken in, because I did some flying with it many years ago (not much though). That actually leads me to another question... when I used it years ago, I wasn't so particular about rpm's and tuning. With a low pitch prop like this, I guess I'll need to run it richer? I have a tachometer these days, so I guess I could use that to check that it's not over-peaking with the 10x4 trainer prop?

The trainer prop offers a few nice characteristics useful for the first few flights... been a long time and I'll have the jitters even if for no particular reason. I'll change to a normal prop soon after.

Cheers :)

RE: Alpha40 special prop
 

For training, The prop I've found seems to be an overall good prop and the one I now recommend for .46 size engines on trainers is the Hobbico NextStar prop. It's an 11 X 5 and holds up as good if not better than any other 11 X 5 prop. The red tips are nice at idle for a beginner to see, and the seem to cost a bit less than other props.

Hogflyer

RE: Alpha40 special prop
 

Personally, I like that prop when I'm instructing. It's espeically useful when teaching/learning approaches as it provides a bit of extra braking, giving the student more time on final.

After solo, I recommend they go to a normal prop.

I have a well-used Evolution trainer engine in an LT-40, and I use an APC 11x5 prop. I pulled the baffle out of the muffler, and that combination works great for a slow flying plane where you want a lot of pull. The Alpha is a cleaner airframe. With a 10x7 and a big spinner to smooth out the airflow around the front of the plane, the Alpha can really haul tail (for a trainer, but it's the fastest trainer I've seen)

RE: Alpha40 special prop
 

Thanks for replies. So now I have the size of the Alpha40 trainer prop more or less confirmed I guess: it's something around a 10x4. The Evo trainer prop that I ordered is 10.5x4 and I wanted to check if in fact I'm getting the same thing that is intended for the Alpha40 as a trainer prop.

Thanks for the feedback about flight training with this prop. I've had some indecision about whether I should use it even just initially.

The question I still have is about using the Evo trainer prop with my more powerful TT pro 46. From what I understand, I'll just tune it to run a bit richer than usual and use the tachometer to make sure that my TT pro is tuned so that it does not over rev above it's rated max rpm (because of the low pitch). Is that all I need to worry about? After my first few flights I'll change to 11x5 or 11x6 (I have a 10x7 also).

Or would the Evo trainer prop be just not good for a TT pro 46 even temporarily?

Thanks guys

RE: Alpha40 special prop
 

You won't hurt the TT pro with that prop, even if you set it as lean as you want.

That prop actually loads the engine more than you'd think based on the pitch and diameter alone. First, it has the extra blade, but just as importantly, the blades are really wide, lots of area there. Compare that to a prop made for really high RPM like the pylon guys use. Those props have very narrow blades by comparison.

I forgot to mention, I also have a TT Pro .46, and while it's a powerful engine, it's not THAT much more powerful than the Evolution. Maybe a couple hundred RPM, max. Not the kind of differnece that would be an issue with props and over-reving the engine.

RE: Alpha40 special prop
 

Ok nice. Some engines have surprisely less hp than others of same displacement and I've gotten the overall impression that the Evo trainer engine is like this, but I guess not.

New questions keep popping to mind as I return to my thread... Have you ever had to dead-stick with the Evo trainer prop? I was wondering if you'd get significantly less glide time. But I've read that the wind resistance is only part of the story of how the prop adds "breaking"... Supposedly it's partly also sort of like down-shifting when you reduce throttle (because of the paddle-like blades, it bites the air a bit more).

But anyway, is dead-sticking any more of a challenge with it?

Cheers

RE: Alpha40 special prop
 

The Evolution prop should work OK on the TT .46 Pro. I just ran in an Evolution .46 on an Alpha 40 using the stock 3-bladed training prop for a student and we tached it at 11,660 RPM. You'll get around 13,300 RPM or slightly better from the same engine with an 11 X 5 2-blade on it.

There is no need to run the engine rich - just peak it and richen it 400 RPM and you'll be set.

Hogflyer

RE: Alpha40 special prop
 

I've lost count of the number of deadsticks I've had with that prop due to running out of fuel. It was a running joke one summer that I never landed a trainer until all the fuel was gone...

There might be a little more drag on a deadstick, but the Alpha's over all clean airframe probably makes up for it. Anyway, no, there's no noticeable difference with that prop in a glide. Things like the CG location and the wind make much more of a difference.

And no, the Evolution engine is actually more powerful than average for engines in it's class. It does have a smaller muffler than many, and since it comes with that prop and flywheel on the prop hub, it gets a bum rap. But if you replace the muffler with the same muffler as on a TT or OS, and use the same prop, you get an engine that is right up there. RC Report did a great roundup of engines in that size class a while back where they used the same mufflers and props and such, running them side by side to really make solid comparisons. The Evolution came out in a nearly dead heat with the TT, the OS FX was just a hair better, and the OS AX is just slightly better yet. In the real world, things like how the engine was broken in and how it is treated will matter far more than the name on the crankcase :D. (breakin alone can make nearly 2,000rpm difference between engines of the same make). Add in manufacturing tolerances, and it's all the same. I have a pair of OS .46AX engines on a twin, and one of them is noticeably more powerful than the other. Yet they were bought the same, broken in the same, and always run together. Go figure.

RE: Alpha40 special prop
 

The resistance of the prop on a dead stick landing is a non issue. You just fly it to the ground. Believe me, you won't even think about the difference in the drag. I don't think an engineer would see the difference while trying to land it dead stick.. [)]

RE: Alpha40 special prop
 

Yeah it's sort of opposite to what I was thinking. Makes sense based on stuff I've read about the prop. Even if it has less pitch, in a manner of speaking, it "bites into the air more firmly".

RE: Alpha40 special prop
 

Ok thanks. Come to think of it, I guess I'll be making sure to keep the plane fairly high up anyway.

RE: Alpha40 special prop
 

Answers my question I guess :)

The Alpha is a good plane for a trainer. I haven't flown it yet, but from what I can see, I like it alot more than the trainers I flew years ago. I'll be meticulous about the CG and checking trim, so that it's ready for anything.

Thanks guys

RE: Alpha40 special prop
 

Got my Evo 10x4 trainer prop today. A good way to describe it is "very rugged". Looks and feels like really good quality.

I suppose you could even use this for maidening other 40-size non-trainer planes... maybe not great idea for some planes.

RE: Alpha40 special prop
 

No, it actually does quite well and is comparable to the higher HP .46's in performance.

It's almost impossible to tell the difference in the H9 P-51 PTS trainer ( WITHOUT the training aids ) when using an 11x6 prop and the Evolution PTS engine, as compared to the AX .46 with the same prop, on the same plane.

The PTS has a .455 CU displacement versus the .46 CU of the .46 AX... not much of a difference.

The purposely designed highly oblique prop accounts for people thinking that the engine doesn't put out a lot of power.