Best TWIN Replica/Racer ideas

[matt]

wayne, i believe ducted fans are known as "impellors"

[Race5]

That's the word I was looking for....thanks Matt

[Mayo]

Hughes built a twin engine fighter with rather large radials,
then crashed it,
how might this design stand up to the competition at the pylons?

[matt]

the hughes f-11 might be good for straight line speed, but it's overall weight might be a limiting factor. it had 2 4360's and was an EXCEPTIONALLY clean design. there never was a top speed set for it because hughes kept his hand over the meter during it's run, i think it was probably worth around 450 at 20,000 ft though.

[MattB]

Hughes xf-11

I found a photo of this on the web. It looks to have contra props. How common was it to have contra props? I know some Spits had them.

MattB

[FlyinLo]

XF-11 = P-38 on steroids?

With a winspan in excess of 101 feet, it seems like it would be a handful on a closed course. The USAF Museum site describes it as a reconnaissance plane, so it may not have the maneuverability of the fighters flying the course today. It appears to be a twin boom design much like a P-38, only bigger. There's a short description and a 3-view as well as photos with contrarotating props as well as standard 4 blade props on the USAF Museum site at http://www.wpafb.af.mil/museum/fta/fta997.htm if you're interested.

[FlyinLo]

More on XF-11

I found another article on the XF-11 here http://www.edwards.af.mil/articles98...cover/xf11.htm on the Edwards website, which describes the contra-rotating prop pitch problem that almost killed Hughes after which he ordered that standard four blade props be installed on the second prototype.

[Unregistered]

This was not a problem with CR props specifically, but with the type and technology of CR props of the time. A good CR prop (such as that designed by the Russian TsAGI for the AN-70) would not allow an uncommanded feathering of one set of blades. In fact, modern CR design links the pitch of BOTH sets of blades together and requires hydralic pressure for any pitch change. This results in the safety feature of loss of hydraulic pressure = no pitch change.

Fully counterweighted props are better, in that the counterweights force all of the blades towards feather in the case of hydraulic failure. This pushes the blades towards zero rotational force upon hydralic failure commonly referred to as "auto feather". Since most modern Western Bloc R&D has focused on ducted fans, CR props of this type are not readily available in the west.

Eric Ahlstrom

[First time Juke]

I have an idea !

I made several interestin racer ideas and at least two in 2001. For more information send me an e-mail.

Juke