Best Glide Speed & Prop Speed

[MachFly]

I made a series of tests today to figure out Spit14's best glide speed. I took a Spit14 with 50% fuel and used the SW spawn at A22 in the training arena. Prop RPMs were set to minimum.

TEST 1: Used 175mph for the first test (HTC's programed autoclimb speed for Spit14). After landing, I asked someone to serve as a reference point for my further tests. Had him put his airplane right where my is in order to measure distance for further tests.

TEST 2: 200mph, landed 5K before the reference point.
TEST 3: 165mph, landed 3.1K after the reference point.
TEST 4: 140mph, landed 3.3K after the reference point.
TEST 5: 130mph, landed 3.3K after the reference point.
TEST 6: 135mph, landed 3.8K after the reference point.

135 mph is the best glide speed for Spitfire mk XIV is this configuration.  


I know in reality the plane will glide further with prop stopped than feathered. So I decided to test if HTC implemented this in AH.

TEST 7: Used the same 135mph as before. With the engine ignition off I had pitch up and reduce my airspeed beyond stall to 20mph which caused the airplane to climb another 2000ft, then since the airplane was already in the stall I had to dive down to initial altitude to recover from the stall. Then I continued the glide. I landed beyond 6K from the reference point so I do not know the exact distance. Since in test 6 I landed 3.8K from the reference point I this test proves that the plane glides better with the prop stopped. Additionally in test 6 I overflew the reference point at 2000ft MSL, in test 7 I overflew the reference point at 4000ft MSL, which additional proves that gliding with prop stopped results in a longer & more efficient climb.


This demonstrates that the energy lost due to maneuvering to get the prop to stop can pay of assuming that the glide is from a relatively high altitude.

Note: It will not necessarily pay off if the glide is from a low altitude.

WARNING: DO NOT DO THIS AT LOW ALTITUDE AS YOU MAY NOT RECOVER FROM THE STALL.




Special thanks to Electric for dedicating his time acting as a reference point.

[Chilli]

Machfly, interesting how you are doing your tests. 

I have a question, if you are interested in trying a similar analysis.

What is the best auto speed climb rate setting for Ju88s 50% fuel (dot speed command)?  I am looking to do some torpedo exercises to get Ju88s on the deck from 7k feet altitude at full speed to torpedo drop speed ~ 150 mph.

I was able to do this rather efficiently by setting a low auto climb speed 134 mph and shutting off the engines.  Once the speed was sufficiently slowed I dropped as many flaps as I could manage.

My intentions was that with flaps deployed near the deck when I started the engines the speed would not exceed the drop speed for the torpedos with minor throttle adjustments.

[AWwrgwy]

Machfly, interesting how you are doing your tests. 

I have a question, if you are interested in trying a similar analysis.

What is the best auto speed climb rate setting for Ju88s 50% fuel (dot speed command)?  I am looking to do some torpedo exercises to get Ju88s on the deck from 7k feet altitude at full speed to torpedo drop speed ~ 150 mph.

I was able to do this rather efficiently by setting a low auto climb speed 134 mph and shutting off the engines.  Once the speed was sufficiently slowed I dropped as many flaps as I could manage.

My intentions was that with flaps deployed near the deck when I started the engines the speed would not exceed the drop speed for the torpedos with minor throttle adjustments.

**Hijack**

Ju88 has dive brakes that actually work as brakes. Deploy them on the deck and it will drop you below 200 rather quickly.

wrongway

[FLS]

Once you stabilize the glide you can just time the 1000ft altitude loss and figure the distance covered according to the speed. Mind the hypotenuse.

[MachFly]

Machfly, interesting how you are doing your tests. 

I have a question, if you are interested in trying a similar analysis.

What is the best auto speed climb rate setting for Ju88s 50% fuel (dot speed command)?  I am looking to do some torpedo exercises to get Ju88s on the deck from 7k feet altitude at full speed to torpedo drop speed ~ 150 mph.

I was able to do this rather efficiently by setting a low auto climb speed 134 mph and shutting off the engines.  Once the speed was sufficiently slowed I dropped as many flaps as I could manage.

My intentions was that with flaps deployed near the deck when I started the engines the speed would not exceed the drop speed for the torpedos with minor throttle adjustments.

I would not mind making another test but I'm trying to figure out what exactly your looking for. As Wrongway pointed out the Ju88 has air brakes which works very well. I tried it out last night real quick; you can accelerate the Ju88 to ~400mph (a bit less) open air brakes and pull out at 2000ft AGL. Since I don't usually use torpedoes I am unfamiliar with the minimum altitude at which they can be released, if you tell me that I will be able to give you the exact numbers for when to pull out and when to open air brakes.

Also you want to do it without the drones, right?

[Chilli]

I only tried it by using flaps and turning engines off, and I was using drones.  Good to know about the dive brakes. 

I was reviewing a very well done "how to" torpedo drop and in it they showed the Ju88s at ~150 mph and 20 ft off the deck.

Sorry for the hijack, I am hardly ever successful with torpedoes, and I am trying to improve that by coming in at altitude and then quickly hitting the deck and coming in at proper speed.  With the additional information about dive brakes, that might be the missing piece of the puzzle for me.

http://electraforge.com/brooke/flightsims/aces_high/torpedoBombing/torpedoDrop.htm

[Gianlupo]

I took a Spit14 with 50% fuel and used the SW spawn at A22 in the training arena.

Is this an airstart? And, if so, at what altitude?

[MachFly]

Is this an airstart? And, if so, at what altitude?

Yes, the SW spawn at A22 is at 12,000ft MSL