Ducted fan aircraft

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Malish

Well-Known Member
Joined
Oct 11, 2013
Messages
524
Location
Russia. City of Volgograd
770lb thrust.. that’s very close to what 2 PBS TJ100 or TJ150 could do. Any thoughts about adapting/retrofit it for those PBS jets. Only weighs about 100lbs for two jet engines.
Absolutely, not suggesting to divert focus to turbine version. Better get the ducted one working now and see if possible to do that in future
The idea was to have jet fighter looking airplane, that also flying like a jet(no prop moments), but same time be not expensive to own and operate and can be flown by average GA pilot(not jet fighter pilot).
In the future, this aircraft will be electric powered, but still with duckted fans.
 
Last edited:

nicknack

Active Member
Joined
Jul 27, 2008
Messages
43
Fuel


Fuel consumption at full power is 59.5 US gal./hr. Where do you get the 30 gph figure from?

So two engines at full power, about 120 gal./hr. Times about $4.60/ gal.= $552/ hr. in fuel costs.

At 60% thrust up high, $331/ hr. Let's say an average of $400/ hr. Not within the range of most people's pocket books.
My numbers are for each engine..
for both engines working it will x2 as you pointed out.
Full power only for turbines only sustainable for takeoff, cannot be used for whole hour unless you want to do an inspection every few flights. Maybe burn 20 gallons to reach FL180, depends on what climb rate, I am assuming 1500 to 2000ft/min is no problem for turbine version.

Max continuous is at 80%. Fly at FL180 or just below if using non-pressurized mask oxygen delivery. Hopefully flying close to 300kts with a total fuel burn of 28 to 32gph. Now if a 800lb class turbofan gets developed fuel consumption should be reduced to 60ish+ percent.
 

nicknack

Active Member
Joined
Jul 27, 2008
Messages
43
The idea was to have jet fighter looking airplane, that also flying like a jet(no prop moments), but same time be not expensive to own and operate.
In the future, this aircraft will be electric powered.
100% agree, electric will be great. Let the turbines work in big combined gas cycle Electric generation plants. With electric engines being smaller, less vibration, maybe even pitch variable fans are possible and no loss in h/p with altitude.

Cost wise, the pbs TJ100 is 40k per unit full fadec everything included brand new, not cheap but cheaper than one from the big manufacturers. If it ever comes down to 30k or so per unit it’s a very attractive price.
Guess we will know the maintenance cost from the sub-sonex community in future.
 
Last edited:

rv6ejguy

Well-Known Member
Joined
Jun 26, 2012
Messages
3,749
Location
Calgary, Alberta, Canada
My numbers are for each engine..
for both engines working it will x2 as you pointed out.
Full power only for turbines only sustainable for takeoff, cannot be used for whole hour unless you want to do an inspection every few flights. Maybe burn 20 gallons to reach FL180, depends on what climb rate, I am assuming 1500 to 2000ft/min is no problem for turbine version.

Max continuous is at 80%. Fly at FL180 or just below if using non-pressurized mask oxygen delivery. Hopefully flying close to 300kts with a total fuel burn of 28 to 32gph. Now if a 800lb class turbofan gets developed fuel consumption should be reduced to 60ish+ percent.
I think you need to check your math. BSFC on the manufacturers site is listed at 1.167 lbs./lb. X 337= 393 lbs/hr. divided by 6.6= 59.5 GPH X 2 = 119gph for both engines. Might make 70% power at 18,000 feet so that's 83 GPH in cruise. At least 100 gph in climb and probably at least 30 gph on the ground at idle for both engines.
 

Doggzilla

Well-Known Member
HBA Supporter
Joined
Jun 2, 2013
Messages
2,303
Location
Everywhere USA
Ya, I dont know where they are getting the numbers in their brochure, but if the SFC efficiency is correct then its 119 gph at full thrust.

At least one of their numbers is very wrong.
 

Malish

Well-Known Member
Joined
Oct 11, 2013
Messages
524
Location
Russia. City of Volgograd
Ya, I dont know where they are getting the numbers in their brochure, but if the SFC efficiency is correct then its 119 gph at full thrust.

At least one of their numbers is very wrong.
I see that, at full thrust is 150 liters/hr(39 gal/hr) per engine. But our aircraft will need 4 of TJ-100 engines to create needed trust, that is 600(158 gal) liters of fuel needed for 45 minutes of flight!
Our aircraft holds only 280 liters(73 gal) of fuel, that means 20 minutes of flight.
Better go with electric power!
 
Last edited:

nicknack

Active Member
Joined
Jul 27, 2008
Messages
43
I see that, at full thrust is 150 liters/hr(39 gal/hr) per engine. But our aircraft will need 4 of TJ-100 engines to create needed trust, that is 600(158 gal) liters of fuel needed for 45 minutes of flight!
Our aircraft holds only 280 liters(73 gal) of fuel, that means 20 minutes of flight.
Better go with electric power!
Yup... electric will be great if/when we get the next gen batteries to be more than 2x current densities of ~1MJ/kg.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,427
Location
North Carolina
Malish, you should see if you can get a photo of your plane lined up with a MIG and a Sukhoi. Perhaps offering to give the right person a 'test' flight would help?
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,427
Location
North Carolina
I think you need to check your math. BSFC on the manufacturers site is listed at 1.167 lbs./lb. X 337= 393 lbs/hr. divided by 6.6= 59.5 GPH X 2 = 119gph for both engines. Might make 70% power at 18,000 feet so that's 83 GPH in cruise. At least 100 gph in climb and probably at least 30 gph on the ground at idle for both engines.
It's worse than that. Turbine BSFC climbs rapidly as thrust is reduced.
 

AdrianS

Well-Known Member
Joined
Jul 5, 2014
Messages
516
Location
Australia
Did you see our PJ-II "Dreamer"? It's on the grass, behind red "Yak's" and of the left wing of Su-34, painted in the same collars(blue/light green).
View attachment 88514
I did.
It took a bit of panning around. So many blue twin-tailed aircraft there!

I liked the pop-up info on all the planes when you click on them, even though I don't read Russian - that's how I confirmed that I'd found the "dreamer".
 
2
Top