Hot starting a M20K Rocket

[carusoam]

 

http://allamericanaircraft.com/contact.htm

Jimmy owns the business.  David has been there since I started flying in the 90s..?

Both are fabulous resources. Along with demonstrating the power of the O, David set me up with a transition trainer to help me bring my bird from Texas to NJ... (Many years ago)

Best regards,

-a-

 

 

[Guest]

Your engine will be very heat soaked on a brief stop, fuel in the lines and flow divider will boil, flowing to the nozzles, priming the engine with fuel vapour.

from my experience with many engine you will need to add some fuel to fill the flow divider and lines.  This is with either the prime switch or Hi boost(same pump as you've noted). I would then crank the engine with the mixture in ICO and the throttle open about half way.  Once the engine starts you'll have to retard the throttle and with your third hand enriched the mixture, you may have to turn the boost pump to low to attain smooth operation until cooler fuel flows through the lines.

A few other factors to consider, strength of battery and starter, condition of ignition system, (magnetos, plugs and harness) and condition of fuel system relative to TCM SID97-3G and any Rocket instructions.

Clarence

[floridaflyer]

Just now, M20Doc said:

Your engine will be very heat soaked on a brief stop, fuel in the lines and flow divider will boil, flowing to the nozzles, priming the engine with fuel vapour.

from my experience with many engine you will need to add some fuel to fill the flow divider and lines.  This is with either the prime switch or Hi boost(same pump as you've noted). I would then crank the engine with the mixture in ICO and the throttle open about half way.  Once the engine starts you'll have to retard the throttle and with your third hand enriched the mixture, you may have to turn the boost pump to low to attain smooth operation until cooler fuel flows through the lines.

A few other factors to consider, strength of battery and starter, condition of ignition system, (magnetos, plugs and harness) and condition of fuel system relative to TCM SID97-3G and any Rocket instructions.

Clarence

Thanks, what you described sounds like the procedure I've been using, except I use LO boost for 60 seconds prior to priming. I'll try it again with less primer, I may be priming too much.

[carusoam]

Short Thank You to the memory of Houman, who brought us together by starting this thread.  Unfortunately, Houman is unable to join us at this time...

Best regards,

-a-

[floridaflyer]

On 8/9/2016 at 3:36 PM, M20Doc said:

Your engine will be very heat soaked on a brief stop, fuel in the lines and flow divider will boil, flowing to the nozzles, priming the engine with fuel vapour.

from my experience with many engine you will need to add some fuel to fill the flow divider and lines.  This is with either the prime switch or Hi boost(same pump as you've noted). I would then crank the engine with the mixture in ICO and the throttle open about half way.  Once the engine starts you'll have to retard the throttle and with your third hand enriched the mixture, you may have to turn the boost pump to low to attain smooth operation until cooler fuel flows through the lines.

A few other factors to consider, strength of battery and starter, condition of ignition system, (magnetos, plugs and harness) and condition of fuel system relative to TCM SID97-3G and any Rocket instructions.

Clarence

Clarence after going through a dozen hot starts the other day testing different techniques, I must agree with everything you said. My LO boost pump does not circulate fuel in the lines going to the fuel divider/manifold valve or from the valve to the injectors, as there is no return line from there to the tanks. Within 3-5 mins from shutdown, a normal cold start works, but beyond that it requires a hot start. Using a laser temp probe after 10 min from shutdown, the valve temp read 150F and the lines from there to the injectors were 200F. I understand 200F is enough to cause avgas to vaporize particularly if the fuel pressure is low. My fuel system was recently calibrated per SID97-3G. Here is my updated hot start procedure:

1. No boost (LO boost doesn't seem to make a difference, HI boost floods the engine)
2. Throttle and mixture to full
3. Prime 7 seconds (FF rises, then drops, then rises again to stabilize; probably due to vapor getting pushed from the heat soaked mechanical fuel pump past the flow sensor and replaced by liquid fuel)
4. Throttle half open, mixture ICO
5. Crank, slowly advancing mixture
6. When engine fires, advance mixture to full and immediately prime 2 secs, then retard throttle to keep from over-revving.

It's not as smooth as a cold start, but it seems to work. 

[floridaflyer]

On 8/9/2016 at 3:34 PM, carusoam said:

 

http://allamericanaircraft.com/contact.htm

Jimmy owns the business.  David has been there since I started flying in the 90s..?

Both are fabulous resources. Along with demonstrating the power of the O, David set me up with a transition trainer to help me bring my bird from Texas to NJ... (Many years ago)

Best regards,

-a-

 

 

Thanks!

[floridaflyer]

After the kind suggestion from carusoam, I emailed Jimmy at All American. He replied to my email within 5 minutes and I thought I would post his hot start here, hopefully OK with him:

"The Rocket, as you know, is the engine combination that is also on the Cessna 414 / 340. I have more experience cranking the 414 than the Rocket, but I do know one thing. It takes a lot of gas. What I would do is this:

1. Full Throttle

2. Full Mixture

3. Prime for 5-6 seconds

4. Pull Mixture fully back, to cutoff.

5. Low Boost Pump ON right before you start cranking (to keep fuel getting to the engine until engine pump takes over)

6. Normally, 5-10 seconds of cranking you will get a fire going in the engine. 

7. Slowly advance mixture.

8. Adjust throttle to keep it running.

You may have to 'jockey' the throttle and mixture back and forth until you get it running. Sometimes it makes no sense, but going back and forth on some engines will get it running. Other than that, I can't help much. But do know that the continental big bore engine, more often than not, will not start due to too little fuel, not too much fuel (flooding). On Lycomings, it is often times too much fuel."

Note that Jimmy turns the LO boost pump on prior to cranking, sounds like a good idea, I will try it on my next stop and report back.

[Yooper Rocketman]

15 years of hot starts on my Rocket have been pretty much as Doc described, and I've tried a lot of methods others have suggested and always return to what has always been consistent.

Full throttle and mixture full rich.

Run boost pump for 6-7 seconds.

Mixture all the way back to no fuel and prop at 1/2 throttle

As it fires mixture in and throttle back to idle (a pretty quick dance).

Always starts in about 6-8 seconds.

I tried the low boost, as that's what works on the Bo I fly, but it just complicates a known start procedure (and if forgotten, you will not be able to kill the engine with a mixture pull). Don't ask how I know that (on the Bo).

Tom

 

[floridaflyer]

11 hours ago, Yooper Rocketman said:

15 years of hot starts on my Rocket have been pretty much as Doc described, and I've tried a lot of methods others have suggested and always return to what has always been consistent.

Full throttle and mixture full rich.

Run boost pump for 6-7 seconds.

Mixture all the way back to no fuel and prop at 1/2 throttle

As it fires mixture in and throttle back to idle (a pretty quick dance).

Always starts in about 6-8 seconds.

I tried the low boost, as that's what works on the Bo I fly, but it just complicates a known start procedure (and if forgotten, you will not be able to kill the engine with a mixture pull). Don't ask how I know that (on the Bo).

Tom

 

So running low boost (as some posts suggest to cool down the engine fuel pump) doesn't seem to make a difference for our TSIO520NB. Is it because most of the vapor is in the fuel lines and manifold valve on top of the engine where low boost cannot circulate fuel but high boost aka primer does? 

[floridaflyer]

So after one year I can confirm the following hot start works every time on my Rocket:

1. full throttle, full mixture
2. prime 5 secs (fuel flow will climb to 18GPH)
3. 1/4 throttle, Mixture to ICO
4. crank engine and slowly advance mixture 
5. when engine starts to fires give short primer bursts until idles smoothly

 

[jlunseth]

The Pelican Perch procedure may work for the Rocket TCM, but it does not work for my 231.  Pulling the mixture to full lean (idle cutoff) and running the Hi Boost for more than about 15 seconds is the one way I can produce a backfire, so just be careful with it if you are a 231 driver.  What I have found is that the engine will catch and then die simply because there is not a good fuel flow.  If you listen to your engine you can hear it.  The cure is to hit the Hi Boost when you hear the "catch and die" going on.  works under all conditions, altitude, hot start, cold start.  I have not had to hit the starter switch more than once in several years.