Maglin

Hello all. I've recently purchased a trainer with a 66" wingspan and a NOS HB 40 PDP. I'm putting a pre-tuned MAC pipe on it. This is my first airplane and I have no clue what prop I should run, or what is a good starting point for a prop. From what I understand the HB 40 PDP isn't quite as strong at the newer glow engines around but they seem to do better with a bigger or more aggressive prop than the newer ABC engines. So if anyone has used one of these please let me know what I should maybe run on it.

I also don't really know what kind of fuel to run. I was going to break it in with some Byron's 20% oil and 15% nitro, but not to sure what to run from their. I don't really need a ton of power and would like the engine to last a while.

Thank you for any help.

Kweasel

My Feedback: (29)

Start with a 10x6 and verify that the rpm surges around 75% throttle on the ground. Adjust propeller loading or change the header length in order to achieve this. Your big trainer may be able to make better use of an 11x4.

NM2K

My Feedback: (14)

A 10x6 is the standard for .40 to .46 sized engines. The 11x6 is more suited for .52 to .58 sized engines. The 11x4 is great for slower flying models while using the HB .40, PDP or otherwise.

As another gentleman suggested, experiment a bit with the engine to find out where the pipe is tuned. I imagine that it should be set up for a 10x6 prop. Mac's knows their stuff. Don't listen to those that may tell you that a baffled piston equipped engine will realize no power increase advantage when using a tuned pipe. That simply isn't true. Tuned pipes benefit all two-stroke engines.


Ed Cregger

jeffie8696

Itake a selection of props of different makes and sizes (within reason) and fly them then decide.
More often than not I select the one with a slightly lower pitch than I expected because I really like the throttle response.

turbo.gst

My Feedback: (8)

Brian Lee of R/C Report did a .40's sized engine (with stock mufflers) Shoot Out in the mid to late 1980's. This was when it was in the newspaper format. The HB .40 PDP 'Blitz' was used. In that test, only the Rossi .40 bettered the HB. It hit 15,000 with a 10 x 6 in that test. Granted many changes have come in the 25 years since the test, but the 15,000 on a 10 x 6 is still among the best.

Sport_Pilot

I don't think you need a pipe if the point was to try to keep up with modern engines.  The early PDP engines would be less powerfull than say an OS FX 40 but more powerful than the LA 40 that you often see in them.   

Maglin

I got the engine w/o a muffler. It's why I got it so cheap. I only paid $45 for the motor. So I figured I would go ahead and get a pre-tuned pipe for 2x the cost of a new muffler. Still only just over half the price of a new HB 40. This motor is new but old. not sure on date of manufacture but it was made by HB in Germany so I guess it's pretty old since they haven't made these engines in some years. I'm a hot rodder at heart so that spills over into my RC hobby. I'll get a 10x6 and see how it flys. My buddy has a ton of plastic 2 blade props that we'll try out. I'm going to follow the HB recommended break in procedure. It's my first ringed glow engine. All my others where r/c car ABC engines.

Thank you for the tips. I know I've read that some say a tuned pipe doesn't help the baffled motors and some say they did. I do know that it will look good and should be fairly quiet as I got their single quiet tuned pipe. They have a double that they say the prop makes more noise than the exhaust. I'm hoping to have the plane ready to go in about 4 weeks for it's maiden flight.

airraptor

My Feedback: (66)

You said this is your first airplane. With this you are a new to flying and you DO NOT need the tuned pipe hassle for training. run the stock muffler or buy one for it. if you havent ordered the tuned pipe yet dont order it. waste of money for now. learn to fly then step up to a good sport plane then can try the tuned pipe on the HB 40. if the HB is new or close to new looking you can sell it and buy a OS 55 AX that will have plenty of power and can use on many planes out there.


have you joined a club yet?

Maglin

No havn't joined a club yet. I actually was trying to get some OS 40 for $55 that my LHS had NOS but it was gone the next day when i went to go pick it up so I got the HB. It's a new engine. I might put my buddies muffler on it. I think it's a thunder tiger 40. He just recently nose dived it into the ground. We haven't checked to see if it bent the crank but it did break the carb into a few different pieces. Sucked as it was a nice looking Zero. Rx went screwy and he lost all control of the plane. Was a good show. Anyways I think the muffler from it will fit the HB and if so I'll try with the tuned pipe and the muffler. I've been flying the Realflight G3 a lot and have a lot of people at our airport that are more than willing to help me out with training. I have to get my AMA card still. Even though I don't need one as my home owners insurance will suffice but they where a little picky with my buddy last time we went out. I guess 2 million in coverage isn't enough. Feels more like "I paid for it cause I rent so you will pay for it." kind of thing to me.

I also went tuned pipe for decreased fuel use. I read that you get less fuel waste with a tuned pipe. Stuff isn't cheap. I was going to go brushless as I have a ton of Lipo's and brushless cars but about every person at the air park said that gas was the way to go for any large airplane. I'm not looking forward to crashing but I'm prepared for it. Putting a new bulkhead on the Zero and the other few repairs will be a good learning experience for me.

turbo.gst

My Feedback: (8)

The HB 40 shares muffler dimensions with several engines. It does use a #5 bolt that requires you to enlarge it to a #6 size to take advantage of all that will fit. It uses the same stock muffler as the .61, so it allows it to breath very well. As said a 10 x 6 at 15,000 is still a very powerful 40. There are only a few that will beat it on that prop, and those that do are not cheap!

It share the Muffler dimension's with:
HB 40 & 61
Como 51
ST 45 thru 60 ( V-60)
K&B 61 & 65
Webra Blackhead & Silverline .61

Those are one's that I have and I know they interchange with the enlargement to a #6.

jaka

Hi!
A tuned pipe will increase fuel consumption!!!!
That is not the way to go for a newbie pilot!
Get a modern .40 engine with a standard silencer like a ASP, OS od TT , yours is a ringed one and needs longer running in than a modern engine.

Sport_Pilot

I concur, plus you don't really know if or how much the tuned pipe helped if you never ran it on a muffler. You can get a stock muffler from www.mecoa.com as well as parts.