HighPlains

My Feedback: (1)

You guys have heard of YS

flyingfrog007

wish they would outlaw elec. no noise no fun.

iron eagel

HigPlains, that is why I used a vacuum, I was looking at the pressure differential as being the key to the cooling system working. Portions of the ducting system works as the plenums in my setup, while the cowl opening is large only a small portion of the airstream is input into the cooling system and motor. Hopefully I have minimized the cooling system drag to some degree by taking this approach, all I know for certain at this point is that it keeps the motor cool during static test, if it works in flight is yet to be determined. I don't really understand all that is going on in this type of system but used the ram jet idea a a model for how to make it work. I don't by any stretch know all that is going on in cooling a high speed aircraft, I am basically experimenting at this point to see what I can get to work.
All I do know for sure is if I can dissipate the heat the motor will work better and longer.
Wow 3 hp from a .40 that's awesome and daunting at the same time. What your saying is that we are talking about 2300 watts of power for an electric to equal a .40 high performance 2 cycle. I am pretty sure I'm not going to be able to get anywhere near without cryogenics becoming part of the equation.

jjookkeerr

The problem with high amounts of boost is going to be detonation. 6-8 psi is generally considered to be safe, at least in bigger engines. But with running methanol you could get away with more I suppose.

iron eagel

J,
As we now live in the day of nano technology that may not be as far fetched as you might think; incorporating cooling in the actual windings of small or micro motors.
It's probably already been done in a lab somewhere...

garys

Bob (HighPlains),
Funny you mentioned cooling drag. In 1997, Jim Allen and I played around with it on his FAI racers for the world champs. We ran a fully pressure cowled engine/pipe setup, where the air entered the front of the cown and exited at the back of the pipe. The hiccup to this, that everybody did, was we a hole in the cowl for the glow plug. We found that just taping over the glow plug hole after starting the engine would cool it so much it was hard to keep running (obviously cooling air was exiting out the hole rather than going through the whole cowl). We found we had to cut the front cowl opening by over 1/3 if we taped the glow plug hole. At that point the engine set and ran just like the fully open air intake with the plug hole left open. A 1/3 reduction of air into the cowl is a large decrease in cooling air drag. We didn't continue doing it however, as we just didn't see any real results on the stop watch, and getting the cowl taped after removing the glow plug clip was an extra step to go wrong while on the 60 second clock. Most current FAI setups actually let most of the cooling air exit just aft of the cylinder, and don't cool the pipes. It's even been found that the pipes may effectively act shorter the hotter they get. That may actually be why we didn't see an improvement in our times (keeping it cooler made it act longer, limiting how much the engine unloaded).

iron eagel

378

My Feedback: (4)

Well that and the fact that our engines don't like to detonate anywhere near as readily as gasoline ones do. As long as the right plug heat range and head shim count is used detonation is a moot point.

vicman

My Feedback: (10)

Evan, I love you bud, but you aint hit no 2 bills in the company of speed by my count yet.
I do admit you are the king of lekky speed but Bill J is still the fastest man I have seen at 211 and glo power.

That said IFq45o you are close enough to NC to come up here on June 25 and show us what you have at the speed rally.

From what I have seen at pylon races and the speed rallies I do agree that glo has hit the wall and lekkies are the future, however I personally haven't drank the koolaid yet and made a complete change.

jjookkeerr

really to make cooling the windings internally is figuring out how to draw wire that small and still keep it hollow. Probably be very touchy to use, but it would help a lot in the cooling

jessiej

It all depends on what you like. Internal combustion engines have held my interest for several decades now. I become bored by electrics in seconds.

jess

HighPlains

My Feedback: (1)

Gary,
That is interesting what you and Jim found from the leak of air around the plug. As far as the temperature of the pipe, the speed of sound varies with the temperature of the gas. So I guess covering the muffler on my 426 Jett with a layer of mud is not a bad landing, just a method to get more unload in the next heat.

ARUP

Will just have to have 'wet' and 'electric' events. Hard to compare apples and oranges! Great thread!

SCALECRAFT

My Feedback: (13)

I have both fuel and lipo.

I think both have ups and downs. The fuel ups and downs, most know. The batts, I like the clean easy systems, however I don't have hours at the field to charge a large amp batt. Also I don't want to have a massive inventory of batts either since today their estimated life is aprox 2 years. But for quick day at the field and minimum support equipment, nice to have.

Also in prop electrics, the prop can spin up on you with out notice if you are careless when powered up. Happens.

Steve

iron eagel

Some really interesting info about the effects of cooling on a high performance engine here...
I think the battery power systems still have a way to go, but there has been significant advances made just in the past several years. Obviously electrics are not even close to wet engines in overall performance yet, but I think that day is fast approaching. Like I said before this 4.2 oz motor is rated at 850 watts (1.13 hp) and that's a pretty good power to weight ratio in my book, but to be fair you need to add the weight of the 100amp esc 4/oz and the battery 8oz. with all of that your at a lb for total weight, which in this case matches the total weight of my airframe servos and receiver. But the airframe has very little frontal area so it should prove to be an interesting experiment.

HighPlains

My Feedback: (1)

The more I think about your using a vacuum to draw air through the system for tests and measurements, the more I like the concept. Since it is downstream there is no turbulence to contend with. I'll have to find 50 feet of pipe to move my mighty damn noisy shop vac into another zip code.

Gene Margiotti

My Feedback: (4)

Definitely a fun and colorful debate, whomever participates. But, at all of the electric only airplane events that I've attended I've lost interest in the first 30 minutes.

There is just no magic in going fast without some smoke and noise!!

Gene

iron eagel

I used a pool vacuum hose to get some distance from mine...

oliveDrab

I fly three 60-sized and one 1.20 sized electric plane.

Sig King Kobra + AXI 4120/14 electric motor + ThunderPower 6-cell Lipo (yes, it's pricey) + wooden 12x8 prop = a hot, fast prop plane that sounds awesome! When I fly it, the guys at the field ask me to do a low fly-by just so they can listen to it.

Sig FourStar 1.20 + AXI 5330/18 + 10-cell Lipo + 18x10 prop = ......well.....not sure.....haven't flown it yet.

Broken Wings

My Feedback: (20)

To each his own.

I bought a Eflite Park 480, Eflite ESC three Rev-Lectric Lipos, battery connectors, etc. Charged one of the batteries (left the other two in the package) figured out it (Electric) wasn't for me and sold the whole lot.... I got $75 shipped. I never mounted the motor on an airplane.

Never again....[:'(] Once purchased, I've found electrics to become "Cheap" instantly... I can still get around $50 for a 20 year old glow engine in good shape.

There doesn't seem to be any value for used electric motors much less used Lipos.

Electrics just don't have any soul in my opinion.

Speedy-Gonzales

My Feedback: (202)

Excellent comment CBP!!! They can throw numbers at anything and come up with nothing but theory. You and I both know that the actual accomplisment itself is a far greater task. I just sold ALL my electric stuff. Just not my bag.

I live in Amish Country and they have solved the energy crisis. They have invented a mode of transportation that produces gas and requires none!! It's called a "horse".

For those of you that prefer electric...that is great! My concern is that with the RPM and HP numbers the electric guru's are coming up with that maybe the propeller/impeller will become an obsolete method of propulsion

jessiej

I will agree that electric is superior for some uses. My wife was making a cake a couple of days ago and I will admit that I am glad her kitchen mixer is electric rather than glow.

jess