# Anyone want a jet?

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#### bmcj

##### Well-Known Member
I seem to be a bit brain dead this morning. Everytime I do this calculation, I come up with a different answer. Can someone please confirm my math?

2.7 liters/minute at 250 lbf thrust. Assuming 6.5 lbs per gallon, does that work out to 232 pounds per hour (36 gallons per hour)? This would equate to 0.92 /hr (pound fuel per pound thrust per hour) SFC at full sustained power (250 lbf).

2.7 liters/min * .22 gallons/liter * 6.5 lbs/gallon * 60 mins/hour

Bruce

#### Aviator168

##### Well-Known Member
That's the number I got too; but I remember on his site once I saw something like < 0.5 SFC which is still high compare to piston engines. He is targeting 300mph. IMO, he should reduce that to 200mph and increase the bypass ratio which will lead to a more efficient engine.

#### Lucrum

##### Well-Known Member
Log Member
How much is "least expensive" I wonder.

#### batesjoe

##### Active Member
It would be interesting to see this developed into a turboprop, especially in the 100 hp range and see what the weight would be.

#### Jay Kempf

##### Curmudgeon in Training (CIT)
I'd like to see a full rpm range fuel consumption. I know these things drop off thrust pretty fast with RPM but normally there is some usable range. If it still had 100lbs of thrust at some lower fuel consumption that could be interesting to design a flight mission around. Climb for 10 minutes at moderate thrust and then back off and cruise with lower at a reasonable flight level. Then walk down hill fast for a long way to the destination sipping fuel. For something that was pretty low in drag it would work well as long as it could lift the fuel. A jet would certainly solve the long landing gear pusher issue I always fight with. But big fuel consumption is big fuel consumption. Take say a two place glider and pylon mount the engine and clip the wings and load fuel where the water ballast used to go and get the landing gear to some standard config and you have a really nice cruise platform.

#### SVSUSteve

##### Well-Known Member
It would be interesting to see this developed into a turboprop, especially in the 100 hp range and see what the weight would be.
I would like to see the "piston engine only" restriction lifted from LSAs if that happens.

#### Aviator168

##### Well-Known Member
I would like to see the "piston engine only" restriction lifted from LSAs if that happens.
Is a wankel considered piston?

#### flyvulcan

##### Well-Known Member
Log Member
JetBeetles engines do not have bypass air. They are a turbojet, not a turbofan. In Jetbeetles engines, all the air that goes in the intake passes through the combustion section then out the back.

To make them more efficient, he would be needing to increase pressure ratios, incorporate recuperation etc. and run the engine hotter. This would lead to the requirement for more exotic materials, increasing price....

At some point, he will probably add another spool with a fan, then we will see some improvement in fuel economy.

I've been dealing with Horace for around 4 years now about his H150 which has always been the intended power plant for my Komet. His product has been improving steadily over that period. It is still an engine that requires a fuel/oil premix and will probably need a bearing change every 50 hours, but for probably around $15000, it is one of the more affordable options out there, certainly compared to the PBS Velka engine that is intended to be used on the Subsonex. #### SVSUSteve ##### Well-Known Member Is a wankel considered piston? Yes, I think the stipulation is more "non-turbine" than "piston only". That's what I get for posting while severely short on sleep and jet lagged. LOL #### Aviator168 ##### Well-Known Member To make them more efficient, he would be needing to increase pressure ratios, incorporate recuperation etc. and run the engine hotter. This would lead to the requirement for more exotic materials, increasing price.... Or add a muti-stage turbine and turn the engine into a turboshaft for a lot less money. It is still an engine that requires a fuel/oil premix and will probably need a bearing change every 50 hours, but for probably around$15000,
That's a very attractive price. Considering, jet parts do not wear as much as piston parts.
Didn't he added a recirculation lubrication system, and second spool for the fan in the H550?

#### Autodidact

##### Well-Known Member
.22 gallons/liter
Is this for Imperial gallons? I think US gallons is .261 gallons/liter which would be closer to 300 lb/hr. Well, 275 pph maybe?

I've always wanted to start a formation aerobatic team with mini-jets and call it "The Green and Orange Shuttlecocks". Could add a little humor to airshows.

#### flyvulcan

##### Well-Known Member
Log Member
To convert Horace's numbers to figures we may be familiar with:

H150R: @150 lbf thrust: 1.7 lt/min = 102 lt/hr = 26.9 usg/hr = 178 lb/hr = sfc of 1.19 lb/lbf/hr
H250R: @250 lbf thrust: 2.7 lt/min = 162 lt/hr = 42.8 usg/hr = 284 lb/hr = sfc of 1.14 lb/lbf/hr

Unfortunately with this class of engine, the sfc generally deteriorates rapidly as thrust is reduced due to the reduced efficiency of the engine when it is not operated at its optimised speed. So as an example, on the H150R where the the fuel burn is 26.9 usg/hr at its optimised 150lbf thrust, if the engine is throttled back to say 50% thrust (so 75 lbf), the fuel burn may only reduce to 70% of the 150 lbf fuel burn (note: I don't know the actual figure, this 70% is just for illustration purposes).

I spoke ages ago to Horace about incorporating a closed loop oil system and incorporating a fan on his H150R. At that time, he indicated his intention to do so, but it would be after the launch of the H150R in its current form which works.

If you haven't seen Horace's YouTube video of the H150R running, I've had it on my Komet build log on this site for ages. It's worth a look.

I sincerely hope that he demonstrates one running at Oshkosh because I have been holding off on buying the two that I need for my Komet until I see them running for a sustained period and also reliably.

Horace has always been a pleasure to deal with and I hope his US dealer gives the products a good unveiling at Oshkosh. These sorts of innovations are what we need amongst the experimental fraternity.

#### topspeed100

##### Banned
To convert Horace's numbers to figures we may be familiar with:

H150R: @150 lbf thrust: 1.7 lt/min = 102 lt/hr = 26.9 usg/hr = 178 lb/hr = sfc of 1.19 lb/lbf/hr
H250R: @250 lbf thrust: 2.7 lt/min = 162 lt/hr = 42.8 usg/hr = 284 lb/hr = sfc of 1.14 lb/lbf/hr

Unfortunately with this class of engine, the sfc generally deteriorates rapidly as thrust is reduced due to the reduced efficiency of the engine when it is not operated at its optimised speed. So as an example, on the H150R where the the fuel burn is 26.9 usg/hr at its optimised 150lbf thrust, if the engine is throttled back to say 50% thrust (so 75 lbf), the fuel burn may only reduce to 70% of the 150 lbf fuel burn (note: I don't know the actual figure, this 70% is just for illustration purposes).

I spoke ages ago to Horace about incorporating a closed loop oil system and incorporating a fan on his H150R. At that time, he indicated his intention to do so, but it would be after the launch of the H150R in its current form which works.

If you haven't seen Horace's YouTube video of the H150R running, I've had it on my Komet build log on this site for ages. It's worth a look.

I sincerely hope that he demonstrates one running at Oshkosh because I have been holding off on buying the two that I need for my Komet until I see them running for a sustained period and also reliably.

Horace has always been a pleasure to deal with and I hope his US dealer gives the products a good unveiling at Oshkosh. These sorts of innovations are what we need amongst the experimental fraternity.
It seems to be pretty powerful little beast...but no overhaul time is given...do they brake easily ?

That's the number I got too; but I remember on his site once I saw something like < 0.5 SFC which is still high compare to piston engines. He is targeting 300mph. IMO, he should reduce that to 200mph and increase the bypass ratio which will lead to a more efficient engine.
I am ok with the speed...it is a jet engine after all.

Bigger than AMT NIKE; http://www.amtjets.com/Nike.php

...and even a tad bigger than PBS JT-100; http://minijets.org/index.php?id=58 ...in size smaller too ?

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#### KC135DELTA

##### Well-Known Member
Although these engines are nice, they won't be viable until we get something in the 400lb-500lb thrust class available.

#### karoliina.t.salminen

##### Well-Known Member
I would like to see the "piston engine only" restriction lifted from LSAs if that happens.
So since they have this in legistlation, also electric LSAs would be illegal?

Interesting jet engines. Small jet would be quite inefficient, but it would be very cool.

#### topspeed100

##### Banned
Although these engines are nice, they won't be viable until we get something in the 400lb-500lb thrust class available.
I disagree a bit here..this is the out put of the BD-5J...and when doubled it could carry 2 man.
In fact a Martin Midget close support jet was to operate at only 4.2 kN. It would require 4 x HT250 engines.:gig:

#### KC135DELTA

##### Well-Known Member
I disagree a bit here..this is the out put of the BD-5J...and when doubled it could carry 2 man.
In fact a Martin Midget close support jet was to operate at only 4.2 kN. It would require 4 x HT250 engines.:gig:
Exactly, each one of those applications requires multiple engines (except the bd-5, which isn't a practical aircraft). A single engine turbofan in the 4-500lbf range would be ideal.

#### topspeed100

##### Banned
Exactly, each one of those applications requires multiple engines (except the bd-5, which isn't a practical aircraft). A single engine turbofan in the 4-500lbf range would be ideal.
I guess you are right..there is a man in USA that claims he could revolutionize private aviation economy with such sized high by pass turbofan engine.

#### SVSUSteve

##### Well-Known Member
Karolina said:
So since they have this in legistlation, also electric LSAs would be illegal?
I think it was clarified that it is actually "non-turbine". Sorry for the confusion.

On a related note, I have yet to see a truly practical electric aircraft and am not holding my breath on that.

TopSpeed100 said:
I guess you are right..there is a man in USA that claims he could revolutionize private aviation economy with such sized high by pass turbofan engine.
I guess all countries have their fruitcakes.