Thoughts on the GP-5?

[spacegrrrl]

Re: Thoughts on the GP-5?

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

Absolutely!

We have a lot of car engines in aircraft today. There have even been certified variations of automotive engines for aircraft. The Gerschwinder V-8 project to make a cheap replacement for smaller turbines come to mind. I think a few of those might have even ended up in some ag planes. That was based on a Ford engine (if memory serves). They reengineered a lot from the base engine at the end but it still has an automotive heritage. We have Subarus (didn't Dave Morse have a Subaru in his plane this year?), Ford and Chevy V-6s. A handful of V-8s, VWs, Geo Metro motors. Gear drives, belt drives and direct drive have all been explored.

Remember a replica of the Vickers Vimy was flown around the world with Chevy V-8s! So car engines can and do fly quite well!

All I was commenting on was someone getting a car engines competitive in an air racer. Not yet, but its coming!

Spacegrrrl

[DWYER]

Re: Thoughts on the GP-5?

Why not just go to Nascar and buy a motor straight from one of their builders. Damn thing otta run all day on Sunday....

[FuryFan]

Re: Thoughts on the GP-5?

"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"


And so the Doctor invented The Mouse.

Kevin

[bonzo_buster]

Re: Thoughts on the GP-5?

Didn't the vimy have BMW v-12s?

[FuryFan]

Re: Thoughts on the GP-5?

Spacegrrrl was refering to a replica of the Vimy that recreated a famous flight from England (?) to Australia. It had BB Chevy powerplants (one of which failed and was replaced during the epic journey.) National Geographic had a full article and did a video documentary about it. Highly recommended!

Kevin

[spacegrrrl]

Re: Thoughts on the GP-5?

Didn't the vimy have BMW v-12s?

I was reengined after the tour with BMW engines. I think that is what is has today, although I don't think its flown anymore.

Spacegrrrl

[Race5]

Re: Thoughts on the GP-5?

Why not just go to Nascar and buy a motor straight from one of their builders. Damn thing otta run all day on Sunday....

The problem is they make all of their power above 7500 rpm. That makes life hard on the PSRU.

[spacegrrrl]

Re: Thoughts on the GP-5?

The problem is they make all of their power above 7500 rpm. That makes life hard on the PSRU.

Maybe we need a prop that likes 7500 RPM. :-)

I'd love to know if some variation of Paul Lipp's prop design could work at the higher RPMs you'd see if you did a direct drive with an automotive engine.

I've also always wondered about the prop that was run on the Nemesis F-1. It seemed as though it might have had tips running over supersonic. As I remember John was alway pretty secretive about the details of his prop.

It's interesting to note that all the propellor data collected during the brief "Thundershreek" project in the 50's is still classified. Of course since the incredible loud noise the prop made on that plane made people physically ill almost immediately maybe they consider the prop more interesting as a direct weapons system than an aircraft propulsion element....

Spacegrrrl

[JET1]

beautiful futility

car motors (with the exception of the mazda rotary) will never make reliable aircraft engines for this type of abuse.

[bonzo_buster]

Re: Thoughts on the GP-5?

The Vimy had BMWs when it came to Oshkosh. The original probably did not as it was used to bomb (the BMW plant?) Germany, where the engines were built. No sense destroying the supply chain!

[Carbonprop]

Re: Thoughts on the GP-5?

Maybe we need a prop that likes 7500 RPM. :-)

I've also always wondered about the prop that was run on the Nemesis F-1. It seemed as though it might have had tips running over supersonic. As I remember John was alway pretty secretive about the details of his prop.

Spacegrrrl

I was serving on the crew when Jon Sharp set his first world record at Oshkosh in the original Nemesis DR-90 Formula One racer in 1993. This flight provides a good data point for his propeller tip speed. This flight resulted in an average speed over the ground of 446.19 kph or 277.25 mph or 406.63 feet per second. We can use this speed to estimate the propeller tip mach number. I also made that prop for Jon.

His 54 inch diameter prop was turning as high as 4500 rpm during the run. This means that during a single revolution the tip of the prop traveled in a circle with a circumference of π x diameter = 169.65 inches. The rotational tip speed in feet per second is:

http://www.aafo.com/hangartalk/images/attach/png.gif

The total speed of the prop tip is the vector sum of the forward velocity of the aircraft and the rotational velocity of the propeller:

http://www.aafo.com/hangartalk/images/attach/png.gif

The speed of sound is dependent on the temperature of the air. In Oshkosh in July with the temperature around 90°F, the speed of sound is around 1150 feet per second.

Jon’s propeller tip mach number was therefore about:

http://www.aafo.com/hangartalk/images/attach/png.gif

I don't know if the equation graphics are gonna work so I will just state that:
the prop rotational tip speed is 1060.3 feet per second,
the total tip speed of the prop is 1135.6 feet per second,
the prop tip mach number is .99

[spacegrrrl]

Re: beautiful futility

car motors (with the exception of the mazda rotary) will never make reliable aircraft engines for this type of abuse.

Well, there you go, nothing to see here. Make to sure to let everyone actually working on a car engine for a race plane to stand down. Now that this matter is settled I wonder if I can get a good deal on the GP-5.

I guess we need a new topic, how about why we don't see more biplanes in the unlimited class....

Before we stop talking about this forever is there any chance of sharing your thinking on this subject in greater detail?

(Actualy I like the rotary for this too, but I think there are other great engines that could work)

Spacegrrrl

[spacegrrrl]

Re: Thoughts on the GP-5?

I was serving on the crew when Jon Sharp set his first world record at Oshkosh in the original Nemesis DR-90 Formula One racer in 1993. This flight provides a good data point for his propeller tip speed. This flight resulted in an average speed over the ground of 446.19 kph or 277.25 mph or 406.63 feet per second. We can use this speed to estimate the propeller tip mach number. I also made that prop for Jon.

His 54 inch diameter prop was turning as high as 4500 rpm during the run. This means that during a single revolution the tip of the prop traveled in a circle with a circumference of π x diameter = 169.65 inches. The rotational tip speed in feet per second is:

http://www.aafo.com/hangartalk/images/attach/png.gif

The total speed of the prop tip is the vector sum of the forward velocity of the aircraft and the rotational velocity of the propeller:

http://www.aafo.com/hangartalk/images/attach/png.gif

The speed of sound is dependent on the temperature of the air. In Oshkosh in July with the temperature around 90°F, the speed of sound is around 1150 feet per second.

Jon’s propeller tip mach number was therefore about:

http://www.aafo.com/hangartalk/images/attach/png.gif

I don't know if the equation graphics are gonna work so I will just state that:
the prop rotational tip speed is 1060.3 feet per second,
the total tip speed of the prop is 1135.6 feet per second,
the prop tip mach number is .99

Cool analysis! I wonder if some sort of "supercruise" section (there were some studies on sections optimized high sub mach applications) would be ideal for a prop operating in that enviroment.

It has always seemed like propellor sections are one of those areas that there has been a lot of "magical guessing" and "secret sauce" that some teams apply to occasional great effect.

Spacegrrrl