John Alber & Gary Schulze (A&P IA) Hatz CB-1 Project:
John's email of 14th March 2005 Summarise the reasons in selecting a R2800.
John Writes: We are closer to deciding on a Rotec. Because of weight considerations, we think the 2800 will be best. To summarize where we are:
bought a Hatz with a LOM 332 engine that had experienced a prop strike.
Rather than tear it down, I decided to replace it. Photos of the Hatz
and engine installation attached. The LOM gives the aircraft quite a long
nose and hence quite a long forward moment arm. My preference is to use
an engine with a shorter profile. A radial is perfect. The LOM's dry weight
with accessories is 249 pounds. Its nominal horsepower is 140. It flies
fine with that.
Both cost and weight push me towards the 2800.
So, some questions:
1. Drawings. Can you email a little higher res drawings of the 2800, with CG shown?
reply: CG can be viewed by clicking here. As can be seen its 5" forward of the rear edge of the mounting plate.
2. Thinking about reconfiguring. I will attach drawings of the 332. CG is at the "T" near the generator. Given the LOM's weight and CG, how might you suggest we mount the 2800? Can you use any of our existing mount?
reply: None of your existing mount can be utilised but with a custom built mount the job is easily done...
3. Mount. What is the cost of a mount from you?
4. Prop. What prop do you recommend and what is its cost? My gear has been extended 3", so I can swing a long prop.
reply: A good starting point prop, for cruise and climb is one of 76" diameter and 50" pitch. This is a wood laminated prop superbly finished and costs $950USD. With this 76" prop in place here are some interesting figures:
5. Performance. With a long prop, can you give me any sense of performance? E.g. like an O-320, like something else? Hatz's work well with either O-290s or O-320s
We've found the best way to answer the specific question about performance
is to draw on the various discussions we've had with builders and pilots
who all feel the HP is understated. Here is a distillation of these discussions:
the Rotax swing a 76" prop at 2400 rpm. The answer is no it can't.
But the R2800 at the same HP rating can with ease. Why? Because HP is
not the guiding factor. Torque is the factor that needs to be looked at.
Thanks. - John Alber - Illinois - USA
Some Before Pics
There is a definite air of excitement at Rotec with this Hatz project... This aircraft is going to be nothing short of awesome!
We're hanging out for for the after pics...