[alancalverd]

What is the Mach number of the propeller tips? Current thinking on solar planes is to use several small propellers to improve airflow over the wing and avoid Mach limiting at altitude.

You do raise an interesting point. Solar-powered aerodynamic flight at extreme altitude may be even more useful for communications and surveillance than low orbit.

[topspeed3 (OP)]

Hello Alan and the distinguished readers !

Flying with SSTO ship to Mars is possible.

http://exoscientist.blogspot.fi/2015/08/propellant-depots-for-interplanetary.html

My design is a bit secret nowadays but here is a superbly flying model from 2015 you to see atop the electric 3-wheeler ( made of woodcomposite and to be used in MARS ).

Increased wing area of the lifting fiselage makes it possible..at the lift equation works fine.

I assume since Felix Baumgartner was able to brake the sound barrier in free fall above 100 000 ft that the low mach number is no longer a big issue.....if you are high enough.

Of course everything has to be prepared to make the kite fly in supersonic conditions...but only above 120 000 ft. There the air has low density and viscosity is low. Thus the compression no longer has such vast effect as in thick air at high speeds.

The EAS speed will indicate 100 km/h at all altitudes. This is very important in my humble opinion.

Let's do it !

[topspeed3 (OP)]

You do raise an interesting point. Solar-powered aerodynamic flight at extreme altitude may be even more useful for communications and surveillance than low orbit.

The illusion of solar power combined with battery power is weak force is created by the fact that Solar Impulse and several drones use only a small fraction of the available solar flux to fly during daytime. Drones stay up for months or years etc. Solar Impulse night flying energy consumption is 7 kW....and the craft weights 1600-2300 kg !!!

Batteries combined with solar power in my craft is 5000 kW..that is an enermous force. It weighs ( batteries ) 32 tons if 1 hr available of the max output...the batteries can be dropped with parachutes before rocket flight to orbit.

I read several comments above telling what I do not understand and what I possinbly don't. Don't get me wrong...I have studied this phenomena now for 5 years. Most people are suffering from Semmelweis reflex...due to the paradigm shift caused by the idea of this theory.

[alancalverd]

I have no doubt that you have done your homework, which is why I asked the question about the Mach number of the propellor tips.

I recall that some very good work was done on the subject by a young lad called Frank Whittle who wrote a paper for the RAF engineering college calculating the performance limits of propellors and ended up inventing the jet engine.

[topspeed3 (OP)]

Yes Alan this is a good and valid question.

I figure the larger the props are, like in the 30-ies record setter by the italians, the bigger an advantage...as the paddle has to be big as the air gets thinner. Also a 8-12 m dia props rotate very slowly at high mach speed....if it is found out to be an advantage.

At high the air gets very thin and the viscosity drops a bit too. That is why Baumgartner exceeded Mach 1...in free fall...and felt nothing..as he exceeded the feared speed of sound.

There is also a bit controversy about if Mach 1 can be exceeded at lower with an prop plane as I was contacted by a USAF test pilot who had flown beyond M1 with F-84 Thunderscreech....unlike told in the official news and specs. Unfortunately he never answered me when I asked whether it was in a dive or if the prop was running ?

I can also feather the props just before reaching Mach 1...as the plane stays below M1 until at 36 km altitude ( calculated ). Rocket propulsion needs 90% fuel of the craft to reach LEO ....and lifting fuselage lay out may just provide this feature in an aeroplane.

This could be tested in an 20 m spanning lifting fuselage aeroplane with a kerosene/LOX engine ( hobbyist can make these ). This is a high risk test if done by hobbyists...as the solar cells are expensive and the batteries as well...not to mention the highly volatile rocket fuel. Reaching for instance 50 km ( and M1+ speed ) with an under 500 kg craft would be FAI record in several categories.

I also figured how to neatly pressurize a vehicle for this attempt. Perlan II was close to these conditions.

Rocket flying above 30 km with very low EAS number ( and high TAS ) has never been tried. Temperatures stay low as SS I indicated vs. X-15.

If the props do function above 36 km at EAS low numbers...the large prop rotates 3000 rpm at M7. This could increase the payload significantly if this feature worked at very very high altitude.

Shuttle regained the feel in the controls at 110 km altitude in re-entry.

[topspeed3 (OP)]

I counted some WAYPOINT figures for the crafts ascent to orbit.

Interesting is that the craft has to reach almost orbital speed below 100 km to be able to fly to orbit.

M3 at 60 km and weight 56 metric tons.

M15 at 85 km and 31 tons weight ( rocket fuel burned away ).

[topspeed3 (OP)]

An explanation about intented Mars journey.

Craft is a bit schematic at this stage...intentionally.

[topspeed3 (OP)]

I took some time and counted the braking force in the re-entry...it is massive and 20 km higher than where Shuttle started to brake..which is good news as the heating is minimal.

[alancalverd]

The plane can be flying quite slowly or even not at all, with the prop tips exceeding Mach 1. This is what defines the span limit for a wind turbine, and the characteristic scream of a Harvard trainer!

The speed of sound in the stratosphere is about 300 m/s. 3000 rpm is 50 rev/second, which gives you a maximum prop diameter of about 2m before the tips become supersonic .

[topspeed3 (OP)]

Alan ahoy !

Props are feathered at 36 km altitude just below the speed of sound...read the explanation in the picture above. It is a rocket ship where the props assist it to go to thin air where the rockets are useful.

THAT IS THE KEY ISSUE HERE I AM TRYING TO PROVE !

[topspeed3 (OP)]

It is called feathering !

[topspeed3 (OP)]

However...after having said that ...there is slight change of getting thrust of the props at high...because of Baumgartner ( Felix ).

[topspeed3 (OP)]

I also couted the drag forces in re-entry at different altitudes using max aerobraking area.

Already 40 N at 180 km ! AT 80 km it is dragging a lorry behind.

40 N is much more than the most developed ION drive produces in space.

[alancalverd]

I think you will find here is a very good reason why propellers are not used above 12 km (WWII fighter aircraft) and in fact rarely above half that altitude (turboprop passenger aircraft). At any altitude above 6 km a jet is far more efficient and the props simply become dead weight and drag - two things you really don't need.

How about a multistage system, with a reuseable propeller-driven first stage launching a ramjet/rocket hybrid? Now to get a good payload to takeoff mass ratio, use turboprops or high-bypass jets for the first stage. Even so, there's a huge difference between say1000 kph at sea level and orbital speed (25,000 kph) so a rocket might be simpler!

Remember that plenty of experimental rocket planes have been launched from modified bombers, and most fighters carry Mach 3 rockets that could go a lot faster if they didn't have to track a moving target. But for some reason, all those clever chaps at Baikonur and Pasadena still prefer to go from ground to orbit with rockets all the way.

[topspeed3 (OP)]

Alan ahooy !

Thank you for the comment !

You have to concentrate now Alan. Remember turboporps are used becaus e they are more efficient.

Facebook Aquila cruises at 25 km altitude at 5 kW power...and Helios reached 30 km with just 23 kW...and cruised 7 x faster in 30 km than on sea level...and guess what ? Compared to X-15 ....it heated 99% less than X-15 in the same altutude...using lower EAS speed.

There is no substitude for crossing the thick atmosphere than solar/electric power on propellers. Absolutely none.

This system is exactly 1000 x more cheaper way to haul people to Mars than ITS...and 100 x more efficient per astronaut.

[topspeed3 (OP)]

Here is the new system to gain more altitude before ingining the rocket engine ( Mach 3 is gained via dive from 42 km to 27 km ). Kinda like Baumgartner, but in an orderly fashion.