Climb Speeds with Hotshot

[CAVUCO]

Re: Climb Speeds with Hotshot

John,

Where did I say that you approved of overboosting the engine?

Of course, any pilot would sacrifice an engine's maintenance record in that situation, but I believe we were speaking of routine takeoffs.

 

[John]

Re: Climb Speeds with Hotshot

I guess I misinterpitted you response. Sorry!

John

 

[CAVUCO]

Re: Climb Speeds with Hotshot

No worries.

 

[buchan]

Re: Climb Speeds with Hotshot

I have not had a chance to look at the manifold pressure gauge in the airplane, but I do not recall it having a "red line" The is no manifold pressure red line noted in the POH for the airplane that I can find.

The Lycoming Operator's Manual I have shows the rated power for the engine at 2700 rpm and 28.6 inches manifold pressure. The "Limiting Man. Pressure for Continuous Operation" from the graph is about 28.7 inches at 2400 rpm.

The graph from that manual is attached.

Don

 

[CAVUCO]

Re: Climb Speeds with Hotshot

I believe all the Hot Shots have redlines on their MP gauges, its a placard in the RCM manual. A non-turbocharged engine is not in danger of every exceeding that.

If you look closely, the graph depicts the Absolute Man. Pressure as 28.

 

[buchan]

Re: Climb Speeds with Hotshot

Sorry the graph came upside down. If you look closely at the left graph, which is the Sea Level Performance chart, the "Limiting Man. Pressure for Continuous Operation" from the graph is about 28.7 inches at 2400 rpm and a little lower, at about 28.6 inches at 2700 rpm, at the rated power for the engine. It goes down to 25 inches at 1800 rpm.

There does not seem to be any comment in to manual on transient conditions, or short duration limits.

It would certainly be possible on a non-turbo engine to exceed the manifold pressures in the chart on a day with a very high atmospheric pressure, at a low altitude airport. There does not seem to be any requirement to limit the manifold pressure, i.e. less than full throttle operation, on take-off under those conditions.

Don

 

[neald]

Re: Climb Speeds with Hotshot

Neal, I don't believe that's correct. The Hot Shot utilizes a manual waste gate but it also has a pressure relief valve. The SB is quite clear and the manual waste gate makes it all the more important to observe.

Both item 1 and 2 in your list relate to engines with a MAP controller, so they do not apply directly. Were it not for the additional expense, weight, and plumbing, a MAP controller would be a great addition to the 112 HotShot.

The "cool new thing" is an electrically actuated MAP controller (instead of hydraulic using oil pressure). http://www.taturbo.com/PressreleaseDensityController June 27 2009 _3Page.pdf Of course, it is probably made of solid unobtainium (or is at least priced that way)

The pop-off valve on the RCM mod is set fairly high. I believe it comes in to play somewhere north of 35", but I would have to look it up to be sure.

I did not develop the RCM Mod. Robin Miley adapted it based on an STC that Rajay did many years back. Carl Lee is the current owner and maintainer of the STC.

I used the words "probably not a good idea" because everyone is entitled to their opinion. Personally, I never plan to depart an airport boosted beyond redline. But I would not hesitate to turn the knob if I got into trouble felt additional power would save the day.

Normal departure is made at 2700 and max MP for that altitude. Climb is 26" 2600rpm until 10k feet where it becomes 25" (still 2600RPM). The cruise charts are very clearly annotated and do adjust for OAT. This is all per the flight manual supplement (or at least the one I have).

Regards,
Neal