Twin 720 Racer ?

[bflynt]

Anyone know about a twin IO-720 racer in the works and care to comment on it?

I've read comments on another forum by a known aircraft designer who is designing/building a racer with twin IO-720's for someone with the cash to pay for the design. Of course, silence resulted when an inquiry was made. Luckily we are not constrained by the same gag order here

Anyone care to spill the beans

Bryan

[AirDOGGe]

Re: Twin 720 Racer ?

Which forum?

[bflynt]

Re: Twin 720 Racer ?

It was over on the homebuiltairplanes.com site. They rarely speak of racing over there but it was mentioned in an unrelated posting. I'll see if I can find it again.

[spacegrrrl]

Re: Twin 720 Racer ?

Interesting project!

Found the link to the thread

http://www.homebuiltairplanes.com/fo...aterial-2.html

[gp70442]

Re: Twin 720 Racer ?

Take a look at the latest date on that thread though. Year and a half ago.

[AirDOGGe]

Re: Twin 720 Racer ?




Nice design for the most part, but the small, highly swept vertical fin looks like it would be OK on a single engine competitor, but all but useless in an engine-out situation on a twin racer, especially with it's more powerful-than-stock motors.

If you lost a motor at race power. I'd think you'd want more rudder authority, ESPECIALLY if you lost the left engine in a left, low-altitude turn.

[recips4ever]

Re: Twin 720 Racer ?

Yea, but it looks fast with the tail all swept back like that.

[First time Juke]

Re: Twin 720 Racer ?

I think the long fuse is to give directional stability in engine out situation..the fast speed helps to keep stability too..at landing they can cut the other engine too as did the swedes with their Mosquitos.
The fact that canopy is behind the aerodynamical center will ad stability too I reckon.

[AirDOGGe]

Re: Twin 720 Racer ?

Yea, but it looks fast with the tail all swept back like that.

So does a lawn dart.

[Dudewanarace]

Re: Twin 720 Racer ?

I don't know a lot of details, but I have seen some pics with parts of this airplane in the background. It is much more then a dream at this point. Pretty sure I saw a fuselage, wing with cowlings, etc..

[AirDOGGe]

Re: Twin 720 Racer ?

There's also this drawing on the same forum page. The push-pull engine layout I find questionable, but this one certainly has enough tail fin that pleases my aerodynamic senses (whatever those may be):

[spacegrrrl]

Re: Twin 720 Racer ?

There's also this drawing on the same forum page. The push-pull engine layout I find questionable, but this one certainly has enough tail fin that pleases my aerodynamic senses (whatever those may be):

As I read it that was just a drawing someone else one the forum shared to explain his idea and has nothing to do with the project.

Spacegrrrl

[FlyKidChris]

Re: Twin 720 Racer ?

If this project is intended as a pylon racer, may I ask - which class?

IIRC, the limit on Sport Class is 1,000 cubic inches, so twin 720s is too much displacement.

And I'd guess it would be too light for the Unlimited class.

Or am I wrong (yet again)?

[AirDOGGe]

Re: Twin 720 Racer ?

No worries.

I realize the plane drawing was a different aircraft than the sample in the CGI-generated picture.

I too was just using the former as a visual sample of what I think the size of a proper vertical fin for the racing twin would look like. Maybe a little smaller than that, but still much larger than the first swept-back example.

Sure with a smaller fin you could cut the good engine while landing for extra safety, though I don't see a need for it. I was more concerned of the effects of an engine loss during the heat of battle, low on the racecourse.

There's a good reason why high-performance twins like the A-26 had tall tail-fins with lots of surface area... The same reason applies here. MORE power requires MORE aerodynamic control authority.

[Chad Veich]

Re: Twin 720 Racer ?

The push-pull engine layout I find questionable...(whatever those may be):

Note in the front view the right side shows a pusher while the left side shows a tractor. I'm pretty sure this indicates that the design would be either a twin pusher or a twin tractor but not a four engine push-pull! Surely the designer does not have it set up as a twin with a pusher on one side and a "puller" on the other, right?