Thoughts on the GP-5?

[440_Magnum]

Re: Thoughts on the GP-5?

The camp based on no actual data? What racers can you point to in those 40 years that proves your point.

I point to the LACK of successful racers powered by car engines.

But the real reason I stand by my opinion (and that's all it is- an opinion- no need to get so worked up about what I think) is that automotive engines just aren't made the same way airplane engines are. Different power curves. Different cooling expectations. Different percent time at full power, resulting in fundamentally different bottom end structures and relative sizes of bearings, crankshaft, and supporting structure. Different vibration and G-force environments. Aircraft and automobile engine design has diverged more than meets the eye since 1940. Car engines have actually benefitted much more from electronics, but the *mechanical* considerations can't be overcome by electronics.

I applaud everyone who puts together a plane and flies it, regardless of how they chose to power it, and I'm not saying that car engines are completely unsuitable to kit and sport aviation applications. But they're not the easy source of big reliable horsepower for racing in the air that they are at the dragstrip.

[stuntflyr]

Re: Thoughts on the GP-5?

So how many HP do you think it needed to be competitive today? If you do some basic calcs I think you'd see there was no way the powerplants were going to ever be able to provide the output they needed to do that.

These are really crude calcs but assuming 1600HP (remember that has to be maintained for 10 laps) you would see 500 MPH (assuming that there weren't other aerodynamic factors that make the drag behaviors act in an unexpected manner, which I maintain in the Pond racer there were).

So I suppose that if someone had managed to get those powerplants to make 800HP+ each for all the racing at Reno required to win gold the Pond could have worked. Looking into the realities of the engine a lot of folks like say when raced in cars the motor made 1000HP. If you look in more detail, maybe momentarily and not on gasoline but reliable sustained output levels on gasoline were closer to 550HP on a good day. And that assumes alot of things working optimally like the intercoolers, induction flows and being operated at the optimal RPM. Not sure how close to sorted they ever got things like that on the Pond. Those HP figures are also based on a fresh zero time engine. The Pond Racer engines weren't close to that most of the time.

If you believe the Wikipedia article about the Pond they were making 600HP a side when it was all working, so if that's the case then you'd need 2400 HP to get to that magical far side of 500 MPH.

But the point is a different design would do better with the same HP.

So lets look at the NXT. If you could get 1600HP in an airframe that slick assuming Jon makes 600HP today (seems high to me) the next would do 582 MPH. NXT FTW!! Of course, its too light and no idea how to shoehorn 1600 HP into a NXT (where is that Rosewell alien space tech when you really need it??!!). And at the speed there is probalbly all sorts of propellor secret sauce required.

Remember, crude rule of thumb is cube the HP to double the MPH.

Spacegrrrl

I agree with all that you say about how much power it takes to increase the speed over what it took to get it to 400 mph. My contention is that for 1986 or so (design genesis) it was a good design for the speeds that were going to win Reno. Just like the Sandberg racer, which was a great 1970's design for the speeds that were going to win Reno then.

I have some inside info on the Electromotive engine and the word was that that company was never going to be able to make an engine that was sufficient to be an airplane engine. 400 horse a side was about all one could make available and it wasn't very reliable at that power level, so that was really a huge part of the story. Pond and crew were sold a good story, but the powerplant people couldn't produce.

For the speeds of it's design time period, and for it's ability to be semi-fast with so little power, I believe it is a bit of a marvel. The designer had a reference speed that was eclipsed by time, and the operators had a powerplant that the engine builders didn't understand.

I dig on your knowledge, but you come across with the social graces of an engineer. I'm sure you're a delight in person.

[stuntflyr]

Re: Thoughts on the GP-5?

To 440 Magnum,

Nicely put, and a sensible position.

Ever wonder why sport plane builders and engine builders want to use dragster engines. 10 second engine in an airplane. I always thought there was a fundamental problem there!

[spacegrrrl]

Re: Thoughts on the GP-5?

I point to the LACK of successful racers powered by car engines.

But the real reason I stand by my opinion (and that's all it is- an opinion- no need to get so worked up about what I think) is that automotive engines just aren't made the same way airplane engines are. Different power curves. Different cooling expectations. Different percent time at full power, resulting in fundamentally different bottom end structures and relative sizes of bearings, crankshaft, and supporting structure. Different vibration and G-force environments. Aircraft and automobile engine design has diverged more than meets the eye since 1940. Car engines have actually benefitted much more from electronics, but the *mechanical* considerations can't be overcome by electronics.

I applaud everyone who puts together a plane and flies it, regardless of how they chose to power it, and I'm not saying that car engines are completely unsuitable to kit and sport aviation applications. But they're not the easy source of big reliable horsepower for racing in the air that they are at the dragstrip.

I can definitely understand how you might come to that conclusion.

I think one of the that makes me think its going to happen. Car engines just keep getting better and better. And its safe to say you likely aren't going to just drop in a box stock engine. You'd build it out the best parts and modified for the application. What it is going to take is really needing to do it.

And there have been some pretty amazing automotive records. A Corvette ZR-1 ran at an average of 175.8 MPH for 24 hours in the 90's. That is the sort of thing you'd maybe want to start with if you want an airracing engine.

Right now I don't think you need to do anything outside normal aircraft powerplants in the classes where a car engine is really possible (I think the minimum weight in unlimited makes the Sport and Super Sport classes the only place for an automotive powerplant). But if Super Sport grows a car engine could be the thing that gives you an edge. I don't see anything you could find in the choice of aircraft powerplants that is going to do much better than the engines we see in the fastest NXT racers to date.


Spacegrrrl

[MRussell]

Re: Thoughts on the GP-5?

How about instead of atacking me personally you make a case to refute a single thing I've said. Otherwise give up your life as a Rutan fanboy and get a life.

Spacegrrrl

Let's get clear on this real quick: I'm a Reno fanboy, not a Rutan fanboy, and I'm not attacking you but rather making the suggestion that you stop sucking the fun out of the room every time someone mentions the Pond Racer on this forum. I won't refute you here because this is the wrong place to do it. In fact, you need to get in your car, drive to Mojave, and sit down with Burt. Tell him how you feel, get it all out of your system, and then move on with your life, and hopefully you'll feel better. FACT: horrible risk must be carefully managed to gain advancement in powered flight. But a public crusade to shame Burt and the late Bob Pond is absolutely senseless and will get you nowhere. I am not trying to belittle you, but I disagree with your approach. I respect that you have powerful feelings about the subject, but I take issue with HOW you choose to manage those feelings.

[Sven42]

Re: Thoughts on the GP-5?

Why do you guys keep bringing up drag racing? The engine in the GP-5 is not a drag racing engine.

Steve

[440_Magnum]

Re: Thoughts on the GP-5?

And its safe to say you likely aren't going to just drop in a box stock engine.
Spacegrrrl

Actually, I think keeping as close to stock as practical might be a GOOD thing. If you go all the way back to my first comments, I made the point that if people would turn away from circle-track tuned race engines loosely based on the ancient small-block Chevy and start looking at the (even lighter weight and much stronger in its basic architecture) factory stock, current production LSx-series, good, or at least better, things might happen.

[flyboycpa]

Re: Thoughts on the GP-5?

..or we could get back to talking about the GP-5 (and ITS engine) rather than jumping on each other and rehashing the much-debated topic of auto-engines vs. traditional engines.

Sorry, just tired of the thread drift.

[spacegrrrl]

Re: Thoughts on the GP-5?

Actually, I think keeping as close to stock as practical might be a GOOD thing. If you go all the way back to my first comments, I made the point that if people would turn away from circle-track tuned race engines loosely based on the ancient small-block Chevy and start looking at the (even lighter weight and much stronger in its basic architecture) factory stock, current production LSx-series, good, or at least better, things might happen.

You are probably right, especially in the beginning. Get everything sorted and optimal, then look at engine improvements. I expect starting out with a crate fresh new Corvette engine would be a good base, a solid 450-ish HP and proven durability.

Spacegrrrl

[spacegrrrl]

Re: Thoughts on the GP-5?

I dig on your knowledge, but you come across with the social graces of an engineer. I'm sure you're a delight in person.

Well, I am an engineer.....

I can be more fun in person I expect, I have some great memories of killing time in Reno a while back drinking "Afterburners" with an ex astronaught (sp?) and one of the pilots of the jet exhibition team that year. They said it was a lot of fun basically talking me into setting myself on fire...


Spacegrrrl

[eeyore]

Re: Thoughts on the GP-5?

About automobile engines in airplanes, true no one has made a sucessful racer yet. Yet is a good word. Looking at NASCAR and Offshore power boats both use Chevy Small Blocks and run wide open for hours on end. Trying to get it all to work in an airplane is a challenge but should be more than doable

[gp70442]

Re: Thoughts on the GP-5?

Why do you guys keep bringing up drag racing? The engine in the GP-5 is not a drag racing engine.

I have to go with Sven42 here. I haven't seen where anyone suggested dropping a drag racing engine in any airplane.

While we're on the topic of car engines, last I heard the Falconer V12 is a racing car engine born in a now defunct road racing class. Looks pretty successful to me. Turn the wick up and they all have developmental and other failures along the way.

GP

[Dialtapper]

Re: Thoughts on the GP-5?

About automobile engines in airplanes, true no one has made a sucessful racer yet. Yet is a good word. Looking at NASCAR and Offshore power boats both use Chevy Small Blocks and run wide open for hours on end. Trying to get it all to work in an airplane is a challenge but should be more than doable

Maybe not in a racer yet, but more than doable, done. There are three See Bee's flying with LS Vette motors that I know of.

[spacegrrrl]

Re: Thoughts on the GP-5?

About automobile engines in airplanes, true no one has made a sucessful racer yet. Yet is a good word. Looking at NASCAR and Offshore power boats both use Chevy Small Blocks and run wide open for hours on end. Trying to get it all to work in an airplane is a challenge but should be more than doable

So one thing about the boat applcations. They have an element of the enviroment that stresses them more than any aviation application ever should. The come out of the water, unload, come up against the rev limiter and the get dropped back into the water and put under full load, over and over and over. Harshest eviroment you can find.

They have that sorted these days. You have to know that if there is the proper motiviation someone can make those engines work well in an airplane.

Spacegrrrl

[Dialtapper]

Re: Thoughts on the GP-5?

So one thing about the boat applcations. They have an element of the enviroment that stresses them more than any aviation application ever should. The come out of the water, unload, come up against the rev limiter and the get dropped back into the water and put under full load, over and over and over. Harshest eviroment you can find.

They have that sorted these days. You have to know that if there is the proper motiviation someone can make those engines work well in an airplane.

Spacegrrrl

Spacegrrrl, they do work well. A See Bee with one won Grand Champion Seaplane at Oshkosh.