Ducted fan aircraft

[Doggzilla]

Malish, I don't now who "us" refers to above. As for me--I hope you'll continue your test program exactly as you see fit. Congratulations on your continued progress.

“Us” refers to members who are grown adults and don’t try to turn everything into petty bickering. A group you are not a member of.

Testing different cruise settings is a normal part of testing and included in every Pilot Operating Handbook.

You would know that if you bothered to learn basic pilot skills instead of wasting your time making petty comments and trying to constantly start arguments in every thread.

 

[Malish]

Malish, when you get a chance can you please check some performance for us.

I see that it cruises at 187 and 15gph. Would you please test what speed it cruises at 10-11 gph?

Most common prop aircraft cruise around 150mph/130kts at 11gph.

If you can do 150mph at 10-11gph then it means your existing blades are efficient enough to compete against props in the 200hp power range. That would be better than the 172 or 182, which is more than acceptable for most pilots.

If you can match that with two fans, it probably means a single fan could be used for 100hp and under without performance reduction.

Our airplane was NEVER designed to compete with C-172 or 182, it's a different "animal". Our aircraft "burn" 58 liters(15 gal)/hr at cruise settings of 4000rpm and 90 liters(23 gal)/hr at max(TO) power at 5000rpm. What can you expect from 400hp engine?

 

[pictsidhe]

Could you quote a few books, papers, that I can read on ducted fans... the more technical the better

There aren't any particularly good books on ducted fans.
The aerodynamics of propulsion, Kuchemann and Weber is a general treatment of jet propulsion that is probably the most useful for the duct.

 

[Vigilant1]

Our airplane was NEVER designed to compete with C-172 or 182, it's a different "animal". Our aircraft "burn" 58 liters(15 gal)/hr at cruise settings of 4000rpm and 90 liters(23 gal)/hr at max(TO) power at 5000rpm. What can you expect from 400hp engine?

Your project is coming along very well (with a surprisingly small number of surprises!). You've been very up-front with the intent of the plane, with no unrealistic claims that a ducted fan will be more efficient than an open prop. Your plane is turning out to be what you promised--a great looking fun design that replicates many aspects of a tiny jet on a much smaller budget.

 

[Malish]

general treatment of jet propulsion that is probably the most useful for the duct.

It is not realy - ducted fan design based on different theory and it's different from jet propulsion - there, in ducted fan main Principe of thrust, is MASS FLOW.

 

[Malish]

. Would you please test what speed it cruises at 10-11 gph?

At this power settings on engine(rpm's) this aircraft wouldn't fly very well. And for any reason we should use this power settings? If some one, who wants economy - let him buy C-172.

 

[pictsidhe]

It is not realy - ducted fan design based on different theory and it's different from jet propulsion - there, in ducted fan main Principe of thrust, is MASS FLOW.

Have you read it?

 

[Doggzilla]

At this power settings on engine(rpm's) this aircraft wouldn't fly very well. And for any reason we should use this power settings? If some one, who wants economy - let him buy C-172.

Well, there is an important reason.

If you can match 150mph at 11gph it means your fans can work with most common 200hp engines without losing performance.

It opens a very large market for your fans.

If you were spending $550,000 for a new aircraft, would you buy a Cirrus or Cessna, or would you buy a ducted fan that performs just as well?

Most people would choose a ducted fan.

 

[nicknack]

At this power settings on engine(rpm's) this aircraft wouldn't fly very well. And for any reason we should use this power settings? If some one, who wants economy - let him buy C-172.
View attachment 89524 View attachment 89525 View attachment 89526

Beautiful aircraft, looks great.

Malish... do truly get 400hp @23gal/hr? That works out to a BSFC of 23*6/400=0.345lb/hp-hr.

That’s an incredible number..and is equal to 41% efficiency on par or rivaling the best Diesel engines.
Maybe actual hp is less?

 

[Doggzilla]

It’s a 388hp LS6.

It’s likely not running at full load because it’s not pitched for maximum speed and hits max RPM without full power.

I’m 110% sure of this.

And also 110% sure its capable of higher performance.

 

[BJC]

I’m 100% sure that there is no such thing as 110% sure.

(I’ve told you a million times to stop exaggerating.)


BJC

 

[henryk]

=many answers...

 

[Malish]

Malish... do truly get 400hp @23gal/hr? That works out to a BSFC of 23*6/400=0.345lb/hp-hr.

That’s an incredible number..and is equal to 41% efficiency on par or rivaling the best Diesel engines.
Maybe actual hp is less?

You're right, right now engine is NOT developing 400hp. At TO throttle position the engine have max 4750rpm(our goal to have 5000rpm at TO settings) because the fan blade design and we're working on it to change that. Right now the engine developing about 370hp at max rpm(4750) according to the table of our engine test run on the dyno.

 

[henryk]

=2018,Rakovnik...

 

[Malish]

Have you read it?

Yes I did.
https://massflow.archivale.com/ductbook.htm

 

[Malish]

2018,Rakovnik...

Compere it with our PJ-II "Dreamer" take off even not developing full power yet. Is there a difference in TO performance?

 

[Malish]

If you can match 150mph at 11gph it means your fans can work with most common 200hp engines without losing performance.

It opens a very large market for your fans.

If you were spending $550,000 for a new aircraft, would you buy a Cirrus or Cessna, or would you buy a ducted fan that performs just as well?

Most people would choose a ducted fan.

No, our aircraft can't do that and there no reason even talk about.
Ducted fan is NEVER will be matching the performance of open prop aircraft with same size(power) engines. And our aircraft not costing $550,000 and for someone who wants something better than Cessna, will buy it.

 

[Malish]

It’s a 388hp LS6.

It’s likely not running at full load because it’s not pitched for maximum speed and hits max RPM without full power.

I’m 110% sure of this.

Ducted fan is not open prop - it's can't be pitched for maximum speed, like you do on propellers. Fan designed for max MASS FLOW(thrust) for power available from the engine. RPM's of the ducted fan stay the same - at static run or in the flight at any speed and this is proven on our airplane. When we push throttle for TO power before TO run - engine will rich max RPM's and they stay the same at ALL speed's, you can only reduce RPM's - to reduce power of the engine - retarding the throttle.
Today we did fly our airplane to check economy setting(that you asked for) to the engine - below 3500rpm airplane DON'T want to fly anymore without loosing altitude.

 

[Doggzilla]

Very interesting data Malish! Thank you for testing!

You may have just solved an old mystery.

The fan settings you just tried are similar to the MAXIMUM fan disk loading used on most western ducted fans.

Ducted fans which performed extremely poorly.

Your higher disk loading works much better. Other ducted fans have clearly been using the wrong disk loading.

I will have to build a test drone to investigate further.

 

[Lendo]

Malish, I like it!
Did you consider the Mazda Peripheral Ported Engine?
At 6,000 rpm is the engine is least stress with it 3:1 internal reduction the rotor itself is doing only 2,000 rpm, so at an even higher rpm say 7,000 it's still low stress. No inlet/ exhaust valves to restrict breathing, parts count are well down on a reciprocating engine. I know the Russians have used the Rotary Technology on many larger engines, but with the 2 rotor engine 200 + is very easy.
If weight was a consideration, consider replacing the Cast Iron 'End and Intermediate' housing with something lighter.
Just a suggestion!
George