Turboprop altitude record

[Pds314]

The aim of this challenge is to reach the highest altitude you can using the Breaking Ground turboprops. It need not be sustainable and can be in a zoom climb if you so desire.

This challenge will require a Stock + DLC  crewed airplane capable of horizontal takeoff which has an aircraft-grade cockpit and not a space capsule or external command seat. KAL overclocking is prohibited, as are magic wings and other aero exploits. All parts should be visually connected to the parts they are physically attached to.

Edited May 29, 2021 by Pds314

[Pds314]

My entry:

I modified a plane I used from another challenge, the Thunderstreak, to improve its altitude performance. Managed to get 15131 meters.

This should probably be considered a dummy entry because I'm very sure a purpose built craft would outperform this considerably, but who knows maybe it will be competitive.

The engines have an axle made of pistons connecting them to the prop.

[Vít Salava]

Beat you by a few metres   But seriously, I'm going to try harder. This was literal edge of what the plane was capable of, so next time more wing, less fuel, and reaction wheels to hold the angle...

[camacju]

I'm pretty late to this challenge but here's an entry that can get to 16.3 km in level flight, and probably could get to 17 km with a bit more intake spam.

In VAB

On runway

I hold a 20 degree climb until 13 km and then pitch down to 10 degrees

At this point one of the turboshaft engines flames out, so I can't maintain altitude - if I attempt this run again I'll throttle down at 16 km.

This craft has very low drag and a good lift to drag ratio so it can definitely make it higher.

Edit - I didn't include a capsule, but with a proper cockpit it still could likely reach 16 km. I'll try tomorrow - I guess this is what I get for not reading the challenge carefully

Edited August 14, 2021 by camacju

[camacju]

New entry, this time with a pilot:

In VAB

Climbing

12 km

15 km

16 km

16.4 km max altitude

[chadgaskerman]

A stable, if not concerning max Alt of 16.5km without proper optimization

[camacju]

Hmm, seems like you have a lot more wing area than I do. I guess sailplanes really are the best way to go here...

Also that craft seems pretty optimized already with the exception of the fuel amount. Lots of mk1 parts in stacks

[camacju]

Well, I added more wing area to my plane, and it went way higher than I thought it would - 18.3 km

In SPH - similar to the other design, but I added more wings, reduced the number of intakes, and added two drop tanks.

16 km, still aggressively climbing. Drop tanks gone

17

17.7 km - there was a local maximum of altitude here, but pitching up solved it.

18 km - the engines are really struggling now.

One engine flames out, leading to loss of control

Maximum height 18.3 km

[camacju]

Attempt 3 at turboprop record: "Vega" reached a maximum altitude of 19249 m.

This plane was really hard to control for the entire flight - I couldn't just let Mechjeb hold altitude; I had to babysit it the whole time. Probably due to bad air intake placement - those air scoops actually have a lot of drag. Maybe inline precoolers/nacelles are the way to go?

In SPH

Landing gear ditched at takeoff

18 km, drop tanks dumped soon after this

19 km

Close to being called "19.3 km" - the engines didn't actually flame out here, meaning I had too many air intakes, but if I end up doing another attempt, I'll keep them since I'll definitely need them above 20 km.

Just for fun I brought it down for a landing. Was quite easy actually - stall speed is absurdly low.

Comparison to the first attempt - clearly they're related, but there are definitely differences. Still not as much wing area as @chadgaskerman's attempt, which implies further room for optimization.

[HyperDraco]

I'd like to try this but as not an official entry, rather as a test for my stock, no DLC propeller, because I don't have Breaking Ground DLC just yet.

May I?

[Pds314]

On 8/18/2021 at 12:52 AM, HyperDraco said:

I'd like to try this but as not an official entry, rather as a test for my stock, no DLC propeller, because I don't have Breaking Ground DLC just yet.

May I?

Sure. The one thing I will say is that electric designs don't fit the spirit of the challenge so I will be more impressed if it uses turboshaft propulsion using blower engines.

 

[HyperDraco]

3 hours ago, Pds314 said:

Sure. The one thing I will say is that electric designs don't fit the spirit of the challenge so I will be more impressed if it uses turboshaft propulsion using blower engines.

You have yourself a challenge.

 

[HyperDraco]

Well, one thing led to another and I ended up getting the DLC...

I'm teaching myself how to use this and having a blast.

Now my old 4 turboprop designs are all useless, you'll get a good, rule-centric one soon.

[HyperDraco]

Well this plane is a bit of a stretch,this is only the prototype which was equipped with a Mk1 Lander can because testing, but the main craft will be within the rules with a standard aviation cockpit.

The Draconic ClimbR (yep, ran out of names)

Basically, the fairing set fully covers the body of the craft, and cuts down on drag heavily. The plane had 2 drop tanks which allowed the main craft to climb decently high enough and switch to it's internal Mk1 Fuel tank.

The final height for this mission was 10,223m but the engine cut out for absolutely no reason so I couldn't climb higher.

[camacju]

4 hours ago, HyperDraco said:

Basically, the fairing set fully covers the body of the craft, and cuts down on drag heavily. The plane had 2 drop tanks which allowed the main craft to climb decently high enough and switch to it's internal Mk1 Fuel tank.

That seems to be the best option for high altitude turboprops - I did that for my own submissions.

4 hours ago, HyperDraco said:

but the engine cut out for absolutely no reason so I couldn't climb higher.

You've probably run out of intake air. I've had that happen before - the solution is to add more air intakes. For example look at my "Vega" submission - the wings are covered in radial intakes..

[TheMadKerbonaut]

Hey everyone, I'm new to the forums, but I've tried it myself and got to a pretty low altitude (8km) on a low-power, cobbled-together plane. However, I have some useful data.

These were the average climb rates from takeoff to the altitudes listed:

0-2km 16.67 m/s

0-3km 18.34 m/s

0-4km 18.54 m/s

0-5km 18.34 m/s

0-6km 14.33 m/s

0-7km 14.64 m/s

0-8km 11.32 m/s

Keep in mind that this isn't very consistent, but it gives a general idea of where the atmosphere thins a lot. I built up speed around 2km, 5.5km, and 7.5km, so keep that in mind while looking at the results. 

The atmosphere seems to get a lot thinner above 5km, and then another drop of performance is encountered at about 7.5km. I couldn't climb faster than about 1.5 m/s above 7.5km. (This plane had 18 m/s initial climb rate)

I reached 8,101 m before stalling.

Thanks!