panhndl

My Feedback: (10)

I sent an email to Jett, but thought I'd post here as well just in case someone had something they wanted to add.

I had a Hanger 9 P-51D PTS to start my flying career and thought I would like to have the Hanger 9 40 size P-51D with retracts that is available now.

http://www.horizonhobby.com/Products...ProdID=HAN4440

I thought a good engine for this plane might be a BSE .76L with a 3 or 4 blade Zinger prop.

http://www.zingerpropeller.com/3_bladed_Propeller.htm
http://www.zingerpropeller.com/4_bladed_propeller.htm

If I matched up the power output of the 14 x 4W recc'ed by Jett and got about the same RPM's and load on the engine, would there be anything wrong with that engine/prop selection? I can't think of any, but I'll be the first to admit that there is a lot I don't know about prop load, engnes, and planes. Basically, I'm looking to have a sort of scale looking warbird in a smaller size than is normally available. Having a super speedster isn't the overall goal, but I thought that the added blades might require a little more oomph. Also, keeping th RPM low could sound really cool.

The formula I use for prop load is D x D x D x P x (SQUARE ROOT(N-1)) where D = diameter of the prop, P = pitch of the prop and N = number of blades. I don't know that this is exact, but it's what I've been using.

If Jett rec's a 14 x 4W 2 blade prop, how does one account for the wide prop? Is it close to a 14 x 5 or a 14 x 6? Or do I need to do something else?

Any insight or suggestions would be gladly considered.

bob27s

My Feedback: (19)

Hi,

Thanks for writing. Sounds like a fun application.

Yes, you can run the multi-blade props. I have tried the Zinger 12x6 x 3 on the 76L and it worked well with the Tubro-Jett muffler, and seemed to work ok with the lite muffler too. I have also used the master airscrew 3 blade 12x6. There is NOTHING to be gained in performance it was for a "look cool" application only. But it can work. Key is finding a prop to let the engine run around 10,000 rpm ground peak.

My personal favorite prop for the 76L, with the turbo-jett muffler on it, is a standard blade 14x4. Also partial toward 13x6 Vess. Big prop, lower rpm (around 10,000-11,000). Quiet.... very slow scale performance.

Having said that.......
My old reliable VQ P-51 similar in size to the H9 .40 size, is powered by a SJ-46 combined with a turbo-jett muffler. (photos are posted in a few places in this forum and in a few threads). I run a 12x4 prop on that setup. PLEANTY of power there... and a nice installation.

For your inquiry, the SJ-60L and turbo combination would be AMAZING in this new bird! (not the 60LX, standard version). You may find this better for the P-51 in general. You could try the multi-blade prop, if you select one that will let the engine turn over 13,000 rpm ground peak. The turbo-jett is the key gives you such a broad torque band that the engine accomodates more prop mass/loading.

You can see both the SJ-46 and BSE-76L installations here...
http://www.jettengineering.com/accy/turbo.html

panhndl

My Feedback: (10)

Thanks for the information. I'll look at the 60L, but I'll probably opt for the BSE :-) I hadn't noticed that the 76 needed a bigger sized Turbo-Jett muff, but it might complicate the fit in the cowl. You're advice is much appreciated.

At ground peak, you suggest over 13,000...to what max? 14,000?

And I wasn't looking for the engine to generate massive speed. I think it will be PLENTY of power, regardless, but I was thinking that lower RPM's and higher CC's would be nice for quieter/more scale sound as well as needed to turn the heavier prop for fast speed when wanted.

bob27s

My Feedback: (19)

There really is no max RPM with the 60L ... mainly want to keep it where it works best in a torque setup with the turbo-jett.

Let me know how you make out !

Bob