[LEE]

Hey Patrice. I am using digital servos Hitec 5625 on ailerons, and a single 5645 on rudder, and two HS 225 MG minis on the elevators of my H9 Edge 540 with a ZDZ 40 up front. You'll have plenty authority with only one servo on rudder for this size bird, just use a 6 volt battery to ensure enough power to the servos as digitals use a lot more juice than standard servos. I have a 2700 NiMh 6 volt on mine with no regulator and no problems whatever after flying a summer of IMAc routines.

Good luck!

[AJCoholic]

Originally Posted by Chris Cann

Well, the two engines BME and DA put out the same amount of power
(5hp). But because the BME is smaller is has a shorter stroke (BME: 31mm
DA: 35 mm). And due to the BME having a shorter stroke it will put out less torque, and of course torque being what you want for 3D (not saying you plan on using this Velox for 3D), on the plus side of the BME shorter stroke is better for higher reving HP situations. Also with the shorter stroke it won't feel like it's putting out as much power.

Torque is not dependant solely on the crankshaft throw however, and seeing as how the two engines are equal displacement, the torque at the crankshaft should be similar (since torque is a function of force on the piston multiplied by the throw) assuming the overall power output of the engines are similar (which they are). The BME may have a smaller throw but the piston is larger diameter (and therefore force on it is larger) then the DA.

There are many other things that come into play like con rod length relative to the throw, porting, ect that dictate how the engines like to run, with what props, etc. You cannot simplify things like that as you did IMO...

The best thing is still to find out what a particular engine will turn what size of a particular prop - and see if that will best suit your needs. TAlk to many people who have actually used and flown the engines, not just read about them...

[AJCoholic]

As for digital servos, I like them, but a good quality coreless servo (non digital) is still very good. But, for the cost I like the Hitec digitals, use them a lot (especially the higher end 5945 series) and have had excellent luck with them.

I did notice a little slop in a pair of 5645's that I will be replacing the gears in soon. But they have flown for 3 years in 3 different planes.

[Chris Cann]

Originally Posted by AJCoholic

...TAlk to many people who have actually used and flown the engines, not just read about them...

Thats actually how I got that info.

[aubej]

Originally Posted by AJCoholic

Torque is not dependant solely on the crankshaft throw however....

Good points. There is quite a bit involved when calculating torque. When it comes down to it, if there are any differences they would be negligeable... i.e. you sitting at the transmitting end of the radio wouldn't notice it.

I like my BME very much, but the DA is also a great choice. I don't want to get into the old Ford Chev debate... Both engines are super reliable and offer excess power for 28% sized planes.

I got my BME cause the price was better and it was available.

Ron, you're right about the prop recommendations. Not sure if BME is just being conservative or ...
So far we've all been running 22x8 and 22x10 MSC props, so we'll just have to see when we get the engines broken in and we go up in size how they compare.

When it comes down to it, they are both great engines, you can't go wrong.
Although, my wife does think the DA is prettier. I guess if you're into 'pretty' things, you should go for the DA.

Jason

[Chris Cann]

Just want to let it be known i wasn't bad mouthing BME engines, I was actualyl thinking about one for a gasser that i was pricing out

[ronm]

Hi Jason, agreed on the negligable difference.
I'm using a 22X8 MSC on my DA, turns about 7300 (after one gallon, have not checked it since the last couple gallons)

And no, I didn't buy the DA because it is "prettier"

[scaleguy]

Originally Posted by admin

I like my BME very much, but the DA is also a great choice. I don't want to get into the old Ford Chev debate...

Hey what about Chrysler (ZDZ)?

Just wondering what the weight difference is between the three?

[AJCoholic]

Hey Chris, how come you didnt make the London IMAC? Expected to see you there...

[Chris Cann]

Couldn;t get a ride up