10/23 Raptor Video

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Status
Not open for further replies.

Rataplan

Well-Known Member
Joined
Feb 14, 2021
Messages
202
we import from china containers with parts for electric bicycles. batteries motors etc. all high quality. also, just for fun, we bought once a few small ICE engines as kit for bicycles. very low quality, lot of noise and smell, unusable in town but for outside with 1 kg fuel it goes faster and further than an electric engine with a battery pack of a few kg... (engines have almost the same weight. ). Although the ice produce more, much more heat it doesn't lead to failure, while the electric one produce less heat, it is causing much failures. but back to planes, a battery less system means you need to add an ice and generator . a combination ice+generator+battery pack+electric engines could be good as the ice+generator can be lighter and deliver less power than the electric engines need ,the battery pack can add the needed power. but the less weight of the ice+generator is lost by the extra weight of the battery pack. in a car who needs a lot of power to accelerate and much less at cruising speed ( although in a Lexus the ice jumps in for extra power with direct drive next to generator and cruising does it almost only on battery. very sophisticated and for a big car (for european/middle east) it uses very little fuel.but airplanes cruise at relative high power setting so the benefit is far less and i doubt the propulsion will generate energy back to the battery when the pilot put his foot on the brakes. (joke). my whole point is its an other technical world i know even less about than conventional ICE-s so I only can look at it with common sense and logic. IMHO and experience that's always a good start.
 

PPLOnly

Well-Known Member
Joined
Dec 12, 2020
Messages
173
PM keeps replying on Facebook that the Dan's are top secret and better than anything ever seen before blah blah. Truly legendary vaporware skills
EDFs in the RC world are pretty good. Guessing they’re scaling up the technology similar to how we’ve seen giant scale RC components used in several experimental manned programs now.
 

231TC

Well-Known Member
Joined
Aug 29, 2020
Messages
178
Hasn't even started building this "special" ducted fan yet and he's already promising it's much better than anything out there. The man's unwarranted confidence sure hasn't been shattered by his previous exploits not working out the way he proclaimed. Maybe he really did come up with something nobody else has tried before even with many millions of dollars of research and development, but how about building it and seeing if it works the way the computers say it will before telling everyone how great it is?

I can understand why he did that the first time. He needed to sell his vision to the masses to raise the money to build the thing. But that's not the case anymore. He doesn't want our money, apparently has enough lined up from somewhere else. So just put your head down and build it, then come tell us how smart you are afterward.
 

hohocc

Member
Joined
Apr 5, 2008
Messages
8
Since we have gone off on a tangent...
I saw this recent thread: PM Spamming
There has been so much use of the letters "PM" recently in relation to his Raptorness that I thought initially the thread was relating to PM engaging in non aviation related propositions. I even received one myself.
Anyway clearly I'm easily confused...
 

Martin W

Well-Known Member
Joined
May 14, 2021
Messages
80
Just a thought, maybe PM has binned his AUDI, and bought a TESLA, hence going to E-Power for the NG ????
No doubt the Tesla can produce well over 300 hp .... it is one of the fastest accelerating cars in the world ...... but the battery and motor weigh over 1500 pounds which is extremely heavy for an aircraft.

The car claims a range of almost 300 miles but that is at lower speeds without using heat , air conditioning , lights , or wipers ..... and at the end the car is barely moving.

Point that Tesla up a steep mountain road at full power and battery life would be less than 30 minutes .

Could be done as a novelty item .... take the 1500 lb motor and battery .... add 1500 lb for the fuselage .... it could make several high speed passes over the airport but that is about it .

.
 

Rataplan

Well-Known Member
Joined
Feb 14, 2021
Messages
202
When you do that, all power input changes are made at the engine throttle valve, and all power output changes are made with fan pitch to hold the fan power. This can work, but the wiring and driven motors must be more robust as they are driven exactly as the engine runs, including all speed variation experienced by the engine. Yes, the alternator inertia is large and will tend to smooth the engine pulses some, but it is still real.

The engine has a relationship between power and fuel flow rates that can be mapped, so that the spot for best power per fuel burned at any engine power level is available. The fan has a similar relationship of air speed, spin speed, and blade pitch angles vs power that can be mapped and available. With AC power conversion, you can select power wanted, pick most efficient engine torque and rpm for that power and then run the fans at best speed/pitch for the power available and airspeed.

All of this can be run analytically and checked to see if in this case all the power electronics are worth the trip.

Is it possible to design the fans to run in synch with the engine and at max efficiency? Certainly, but only at one operating point. The rest of the flight envelope also has to work, so you fudge the design so you have decent power available over the whole flight envelope and now your intended operating point is most likely messed up. Lots of iterations and simulations runs getting a decent compromise worked out.

Decouple things with some power electronics and the battery present can remain modest, but now you can run closer to ideal at any power setting you need. And a software geek can have a great time writing the optimization and fly by wire software to run all of this reliably.

And then, as you pointed out, there is the weight of all this stuff that must be climbed.

Billski
in theory and lot of research experiments and tests. but still ice+csp can also work optimal. while electric and ducted fans will develop with time also will ice and props. and combinations. and all will have its ad and disadvantages.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,397
Location
Australian
No doubt the Tesla can produce well over 300 hp .... it is one of the fastest accelerating cars in the world ...... but the battery and motor weigh over 1500 pounds which is extremely heavy for an aircraft.

The car claims a range of almost 300 miles but that is at lower speeds without using heat , air conditioning , lights , or wipers ..... and at the end the car is barely moving.

Point that Tesla up a steep mountain road at full power and battery life would be less than 30 minutes .

Could be done as a novelty item .... take the 1500 lb motor and battery .... add 1500 lb for the fuselage .... it could make several high speed passes over the airport but that is about it .

.

I own a 300+hp Tesla S since 2016, 120,000kms, and I think you are exaggerating ...... just a wee bit.

However, having owned 5 EVs, 3 currently, I do note that EVs do use way more energy exponentially than ICE's do, so there is at least some foundation for your claims, and I would agree that other than 'Island hopping', EV just isn't suitable yet for aircraft usage due to the 'Weight:Range' ratio, that exponentially gets worse as you add battery weight.

It's sort of like if you had a powerful ICE V8 that got 20 mpg cruising, and say 8 mpg when you gun it, the equivalent EV will also get 20 mpg cruising, but only say 4 mpg when you gun it. Of course you need to gun it when taking off and climbing.

Some may remember this from years back that I made for this forum in an electric VTOL discussion, it was my first EV, and it was relative to the same idea for VTOls, eg: that just the 'take off' and 'landing' would use a whopping great amount of your battery reserve/range.

 

Flyfalcons

Well-Known Member
Joined
Feb 6, 2012
Messages
46
Location
Bonney Lake, WA
No doubt the Tesla can produce well over 300 hp .... it is one of the fastest accelerating cars in the world ...... but the battery and motor weigh over 1500 pounds which is extremely heavy for an aircraft.

The car claims a range of almost 300 miles but that is at lower speeds without using heat , air conditioning , lights , or wipers ..... and at the end the car is barely moving.

Point that Tesla up a steep mountain road at full power and battery life would be less than 30 minutes .

Could be done as a novelty item .... take the 1500 lb motor and battery .... add 1500 lb for the fuselage .... it could make several high speed passes over the airport but that is about it .

.
Just needs to do some figure 8's.
 

231TC

Well-Known Member
Joined
Aug 29, 2020
Messages
178
Henryk, not sure how that's relevant to what you quoted from me. I'm talking about Peter's electric ducted fan that is supposedly better than any EDF built before, although it does not exist in the physical world yet.

The Albi is cool and I want one just for fun, but it is neither electric nor is it Peter's superior ducted fan design.
 

rv6ejguy

Well-Known Member
HBA Supporter
Joined
Jun 26, 2012
Messages
4,560
Location
Calgary, Alberta, Canada
I think if you look into the work and time that went into both the Albi and PJ-II fan designs, there is lots to know on on this subject and these are fixed blade designs as far as I recall. I don't think a fixed blade design will be suitable across the large speed range that Raptor is supposed to operate over. A variable pitch design will be expensive to validate and produce. It may need variable blades and stators.
 

Rataplan

Well-Known Member
Joined
Feb 14, 2021
Messages
202
IMHO the advantage must be found in placing electric engines at aerodynamic
I think if you look into the work and time that went into both the Albi and PJ-II fan designs, there is lots to know on on this subject and these are fixed blade designs as far as I recall. I don't think a fixed blade design will be suitable across the large speed range that Raptor is supposed to operate over. A variable pitch design will be expensive to validate and produce. It may need variable blades and stators.
the whole duct thing is very interesting. with fixed fan and stators you can play with fan rpm and airspeed in the duct to obtain and keep optimal AOA . effective or not, reasonable or not? if I would design some duct i would start building a windtunnel ,form a think tank with volunteers and start experimenting with all ideas and theories of the think tank. they could adjust, redesign on the spot, see the results and play and enjoy and learn.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,813
Location
US
the whole duct thing is very interesting. with fixed fan and stators you can play with fan rpm and airspeed in the duct to obtain and keep optimal AOA . effective or not, reasonable or not? if I would design some duct i would start building a windtunnel ,form a think tank with volunteers and start experimenting with all ideas and theories of the think tank. they could adjust, redesign on the spot, see the results and play and enjoy and learn.
If Peter recruits and equips this entrepid platoon of talented, uncompensated volunteers to design his fans, and if they should somehow, miraculously, do what no one else has done, they should immediately invite Peter into their lab and convince him that the breakthrough was his idea all along. That seems the best way to get him to incorporate an idea into his project.
 

Rataplan

Well-Known Member
Joined
Feb 14, 2021
Messages
202
If Peter recruits and equips this entrepid platoon of talented, uncompensated volunteers to design his fans, and if they should somehow, miraculously, do what no one else has done, they should immediately invite Peter into their lab and convince him that the breakthrough was his idea all along. That seems the best way to get him to incorporate an idea into his project.
well, i didn't ment PM, I doubt he is really interested in gaining knowhow. i ment with volunteers more people who want to use the windtunnel for their designs and be able to experiment on the spot and exchange ideas and results with each other . synergy...
 

Rataplan

Well-Known Member
Joined
Feb 14, 2021
Messages
202
=it is big potential in CR Differential systems=both Electric ("CRFLIGHT") or Differential gear/reductor...

=circa 30 % more thrust in comparation with single propeller the same diametr !


PS=
"Peter's superior ducted fan design. "

=???
interesting, but it has 6 blades (2x3). against 3 blades for 1 prop
 

henryk

Well-Known Member
Joined
Mar 8, 2010
Messages
6,289
Location
krakow,poland
interesting, but it has 6 blades (2x3). against 3 blades for 1 prop
2+2 circa the same,but cyclic noise...

CR Diff. Propellers generate smaller noise ! (2+2 is the bests)

PS= blades NOT consume energy,as HP do !

second +=they work good in climbe and cruise...
 

Attachments

Last edited:

BillyJ

New Member
Joined
Jun 4, 2021
Messages
3
When PM was a young lad growing up in Australia there was a locally famous Box Wing Ducted Fan light sport kit developer enjoying his Heyday here post him shipping his prototype over to the USA on a 747 to exhibit and fly at Oshkosh.

That Aircraft was called the Ligeti Stratos and the designers name was Charles Ligeti
Tragically Charles died crashing an iteration of that design during a test flight in 1987.

I was thinking that just maybe PM's subconscious memory of the Stratos's is behind the NG of Raptor?

If you’re interested Aeropedia has a listing for the Stratos along with a photograph,

And at Oshkosh
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
6,813
Location
US
=it is big potential in CR Differential systems=both Electric ("CRFLIGHT") or Differential gear/reductor...

=circa 30 % more thrust in comparation with single propeller the same diametr !


PS=
"Peter's superior ducted fan design. "

=???
Henry,
I think you may have mentioned this before. 😉
(Against my better judgement...)
Can you point me to a source that fully describes this counterrotating prop idea? The theory, the differential gearing mechanism, the testing articles (incl weight), and the testing results, if possible. Testing at typical climb or cruise speeds (rather than static testing) would be especially useful.

With typical wood fixed pitch props, we might see about 75% efficiency in cruise flight. A 30% improvement (75% x 130% = 97.5% efficiency) would be, well, incredible.
Thanks,

Mark
 
Status
Not open for further replies.
Top