Climb Speeds with Hotshot

[CAVUCO]

The standard 112A manual has a climb speed schedule that ranges from 90kts at SL to 80kts at 12000. The Hotshot manual implies a constant 90kt V speed.

I'm curious what others use.

Second question, what percentage improvement does one see in takeoff distance? Since the Hotshot is turbo normalized, the Sea Level numbers in the standard manual should be right on, with the hotshot showing a progressive improvement with altitude gain. I'm looking for some rules of thumb here as there are no published values.

 

[pjdavis67]

Re: Climb Speeds with Hotshot

For climb, I use 26", 2600 RPM, and 90 KIAS from SL to cruise altitude.
I see climb rates from 400 fpm to 1000 fpm depending on weight and air temp.
Climb rates seem constant up to FL 150.

 

[CAVUCO]

Re: Climb Speeds with Hotshot

Awesome Paul. Thanks.

Do you use anything special for determining t/o distance?

 

[RogerH]

Re: Climb Speeds with Hotshot

Jim, I'm just in the process of "feeling-out"/breaking-in a new Hotshot installation on a 112A I purchased this year.

Albeit cooler, denser air here in Salt Lake City in the winter, I've been really impressed by the performance. Usually bouncing around 80kts, 2600 rpm/25" mp I've been getting upwards of 1,200-1,400 fpm up to altitudes of 10,000+. Like I said I'm just getting things felt out but overall it leaves the performance I was used to flying C-172's in the dust!

 

[ksandrew]

Re: Climb Speeds with Hotshot

Jim,

With N377SB and now N1182J, both 112 Hotshots, I have no idea.

Every flight is different, weight, altitude, temperature.

I go 30" for 3 minutes than back off to 27" until I feel safe, then back off to 25" square.

I just accept what I get. 80 knots climb out then 90 knots climb to altitude..

I do have to remember to watch the manifold pressure so as to wind in the wastegate to maintain 25", easy to forget.

I am never in a hurry, or in mountains.

If I get in a tight situation then I will give her all she has.

Life is a barrel of fun.

Ken

 

[NW-FLYER]

Re: Climb Speeds with Hotshot

I have found in winter up north here you do not boost the take off as you already have 29" in below freezing weather. Not to mention if I go level low like 3000' no hot shot boost I get 138 knots IAS at 27" 2450 rpm just to see what she would do then throttling back to 26" for cruse still 135 knots. Cold air is only good for one thing that's flying.
In the hot weather I do what Ken does as he taught me 30" till a steady climb around 1000 ft flaps up about 2 minutes or so then 27" at 90 knots till desired altitude. The normalizing in deed removes the DA of heat for the power how ever you still don't get as much lift out of the wings so you don't climb as well as you do in cold air. Be careful with a full load in 90 plus heat the Hot Shot helps tons with power but it doesn't normalize the air frame if that makes any since. Yesterday I flew and the AWOS said Density Altitude minus 2,000 ft how sweet is that.

 

[CAVUCO]

Re: Climb Speeds with Hotshot

According to the RCM manual,
Takeoff max continuous per placard (28inches is max at SL) and 2700RPM
Climb 26 square below 7000, back off MP by 1 inch above 7000, holding 90kts

The climb schedule is a recommendations according to the manual, but the takeoff does not appear to carry that disclaimer. Boosting to 30in, though allowed per RCM up to 3 minutes (I don't see that in the manual but I believe Carl told me it was so, seems hard on the engine for routine departures.

 

[gmores]

Re: Climb Speeds with Hotshot

Doesn't seem like the engine could have any trouble with 30" - that's normal atmo pressure.

 

[CAVUCO]

Re: Climb Speeds with Hotshot

My MP gauge has a red line at 28 inches.

 

[ksandrew]

Re: Climb Speeds with Hotshot

The "Unofficail" limit is 30" for three minutes and then back off to red line.
I know this is wrong, but years ago I once drove 47 in a 45mph speed zone.

Life is a barrel of fun.

Ken

 

[CAVUCO]

Re: Climb Speeds with Hotshot

Allow me to be "official" for a minute.

According to Lycoming SB 592, there are two items that need to be addressed.

1) Preset density controller senses compressor discharge density and varies the manifold pressure to enable the engine to power up to critical altitude, regardless of the density altitude. Takeoff is at full throttle. However, the red line on the manifold pressure gage is the maximum permissible for a hot day at high field elevation. Refer to the airframe or engine operator’s manual for standard day manifold pressure.
NOTE: Full rated power must have a lower manifold pressure on a below standard temperature day and higher on an above standard day.

2) During takeoff, with low oil temperature, if the throttle is moved too quickly, the manifold pressure can overboost momentarily above its maximum rated pressure by 1 to 2 in.Hg but then returns immediately to the maximum rated pressure. If the overboost does not exceed 2 in.Hg for more than 3 seconds, it may be disregarded. However, if the overboost is longer than 3 seconds and/or exceeds its rated pressure by more than 2 in.Hg, the corrective actions in this Service Bulletin must be taken as instructed in the following sections:
· Corrective Action for Overboost on Engines without a Pressure Relief Valve
· Corrective Action for Overboost on Engines with a Pressure Relief Valve

Hot Shots have a pressure relief valve but the overboost is limited to 3 seconds not 3 minutes, according to the Lycoming

 

[alandotson]

Re: Climb Speeds with Hotshot

Jim,
I bet the "Corrective Action" begins with " Contact Lycoming with your model number and credit score! "

 

[hljr]

Re: Climb Speeds with Hotshot

I remember one Mercury Cougar that was dropped off at the shop many years ago. The customer came and and was just bragging about how "rad" the car had been running the past few weeks. I called him later that day to explain to him he had a extra hole in the block and a connecting rod was not attached to the crank anymore. To make the story short.......this was a supercharged version and the wastgate had stuck closed. He had ignored the boost gauge one day too many.

 

[neald]

Re: Climb Speeds with Hotshot

Allow me to be "official" for a minute.

According to Lycoming SB 592, there are two items that need to be addressed.

1) Preset density controller senses compressor discharge density and varies the manifold pressure to enable the engine to power up to critical altitude, regardless of the density altitude. Takeoff is at full throttle. However, the red line on the manifold pressure gage is the maximum permissible for a hot day at high field elevation. Refer to the airframe or engine operator’s manual for standard day manifold pressure.
NOTE: Full rated power must have a lower manifold pressure on a below standard temperature day and higher on an above standard day.

2) During takeoff, with low oil temperature, if the throttle is moved too quickly, the manifold pressure can overboost momentarily above its maximum rated pressure by 1 to 2 in.Hg but then returns immediately to the maximum rated pressure. If the overboost does not exceed 2 in.Hg for more than 3 seconds, it may be disregarded. However, if the overboost is longer than 3 seconds and/or exceeds its rated pressure by more than 2 in.Hg, the corrective actions in this Service Bulletin must be taken as instructed in the following sections:
· Corrective Action for Overboost on Engines without a Pressure Relief Valve
· Corrective Action for Overboost on Engines with a Pressure Relief Valve

Hot Shots have a pressure relief valve but the overboost is limited to 3 seconds not 3 minutes, according to the Lycoming

While I agree that overboosting the HotShot is probably a bad idea, the information you are quoting is for engines with a Manifold Absolute Pressure (MAP) controller. The Hotshot uses a manual wastegate instead. The 114 HotShot (formerly Magnum) uses a MAP controller.

Regards,
Neal

 

[CAVUCO]

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.

 

[John]

Re: Climb Speeds with Hotshot

Jim,

First I want to thank you for bringing this conversation to light. Many of us have bought our commanders with the Hotshot already installed and just want to learn more about what others are seeing and getting in performance.

That being said you do know that Neal is the owner of RCM as well as the Hotshot for the 114. I would tend to believe the gentleman that builds and installs the units on our aircraft. He should be very familar with the engines. just my two cents worth.

Thanks for the good post and keep questioning something if it does not seem right to you.

John

 

[CAVUCO]

Re: Climb Speeds with Hotshot

I don't believe I said anything inappropriate or disrespectful other than disagree with his assertion as contradicted in the SB from Lycoming (the manufacturer of the engine). The manual waste gate is a reason to more closely adhere to the SB, not a reason to ignore it. Overboosting an engine is not just "probably" a bad idea, it is a bad idea. And it carries with it OEM actions to address. That's not me speaking, its Lycoming. Where does the 30 inch for 3 minutes limit come from? It really seems to be at odds with the OEM technical pubs. Perhaps Neal could address that issue. I've been around long enough that I'd rather not rely upon folklore (ie "unofficial limits") when it comes to my engine. If the 30in for 3 minutes has been approved, why isn't it in the manual and reflected in Lycoming's own SBs? Why does there remain a redline on the MP at 28inches? BTW, I thought Carl Lee was the principle at RCM.

 

[FS]

Re: Climb Speeds with Hotshot

That being said you do know that Neal is the owner of RCM as well as the Hotshot for the 114.

I don't mean to diminish anything that Neal says, since he has owned his 112 for a long time. However, it's Carl Lee that is the STC holder for the HotShot modifications, not Neal.

 

[John]

Re: Climb Speeds with Hotshot

I stand corrected. Thanks Frank.

My Bad

 

[John]

Re: Climb Speeds with Hotshot

Jim,

I never said that overboosting the engine was approved. However while on the subject, too many people are afraid of hurting the engine when they are in trouble. If I am looking a terrain that I think I am not going to clear I will overboost away to get out of the situation. The engine can be replaced. My passengers and my life cannot.

John