36" span Rohr 2-l75 ducted prop plan now with prototype history explained

RJPIoW · Nov 24, 2008, 07:57 AM

Not sure if this is an edf or a ducted prop project, but for a while Ive been thinking about this rather radical 1970's design as a foamie. This delta winged, shrouded fan plane was built by Rohr as a direct competitor to Cessna's dominance of the small plane market. Financial troubles eleswhere in Rohr meant that it got cancelled before it went into production.

From the little Ive found though it appeared to fly well, and now Ive scaled up a 3 view for a 36" span depron version. The wing span resulted from scaling the duct for a suitable prop.

I considered making it a KF wing, but in the end Ive gone for simple 6mm plate wing to replace the original symetrical one.

So far Ive cut out the wing and much of the basic fusalage shape. Im waiting delivery of the UH HXT28-26-CQ 1300Kv Brushless Outrunner that will be fitted with a 7x4 prop inside the duct and hopefully this will arrive this week and then progress can continue

Richard

Edit after posting this was the piece that got me intersted in this plane as a foamie

http://massflow.archivale.com/2_175.htm

JimW · Nov 24, 2008, 09:45 AM

Different and interesting, hope it works out for you.

Beemus · Nov 24, 2008, 01:00 PM

This is cool, you gonna draw up some plans?

eflightray · Nov 24, 2008, 01:14 PM

Some more pictures and info - ROHR 2-175

RJPIoW · Nov 24, 2008, 01:57 PM

Quote:

Originally Posted by Beemus

This is cool, you gonna draw up some plans?

Yes of course - I usually like to complete a prototype before publishing just in case there are errors - or it doesnt fly!

Richard

RJPIoW · Nov 24, 2008, 01:58 PM

Quote:

Originally Posted by eflightray

Some more pictures and info - ROHR 2-175

Thanks - I found that one a few days ago

Richard

Beemus · Nov 25, 2008, 07:45 AM

Quote:

Originally Posted by RJPIoW

Yes of course - I usually like to complete a prototype before publishing just in case there are errors - or it doesnt fly!

Richard

Sweet! This looks like a neat little plane. With the right motor it could be quite a screamer!! I just added this thread to my subscribe list!

RJPIoW · Nov 25, 2008, 11:02 AM

Quote:

Originally Posted by Beemus

Sweet! This looks like a neat little plane. With the right motor it could be quite a screamer!! I just added this thread to my subscribe list!

Ive planned it around a 7" prop. The duct is 7 1/4" ID which is scale

The motor Ive chosen from United Hobbies was about the best thrust I could find with a 7" prop

Model: HXT28-26-CQ Kv: 1300
Thrust: ~500g ESC Required: 18A
Weight: 33g
Suggested Prop: 3cell:7x4.

Ill fit a lightweight 18A Esc and use a 1000mah 20C LiPo with two 8gm servos on the elevons and a 4.3gm on rudder.

Just working out the likely AUW - but I need the motor to build any more - it was shipped a week ago .......

Richard

RJPIoW · Dec 01, 2008, 11:49 AM

The motor arrived and Ive fitted it. A few photos attached to show progress so far. Hope to have a reasonable plan ready soon.

Richard

RJPIoW · Dec 05, 2008, 04:51 AM

More progress - hopefully maiden flight this weekend

Richard

Beemus · Dec 05, 2008, 12:08 PM

I am loving the wheel housings! How are you going to keep the duct from warping during flight? I mean, how will you stiffen the foam ring, or are you going to try it as is first?

DRITCH · Dec 05, 2008, 12:40 PM

Cool. I asked about this a while back and got "it won't work" from RCG members. I kept at it and found that using an actual fan from a ducted fan or even using 2 props (4blade) made quite a difference in speed. Couldn't find that one prop that would give both speed and thrust. 2 6x3's cut down to 4in spin up nicely and still make a good amount of thrust for low amps.

good luck.

BTW mine was a MIG 15 with a big ole tube for a fuse.

RJPIoW · Dec 05, 2008, 04:00 PM

Quote:

Originally Posted by Beemus

I am loving the wheel housings! How are you going to keep the duct from warping during flight? I mean, how will you stiffen the foam ring, or are you going to try it as is first?

Try it first was my plan, although its pretty stiff now and Im going to add a layer oor several of cross weave tape on the outside of the duct

Plan B was to add 1mm CF spokes just behind the prop.

Undercarriage now attached and fuslage sheeting being attached

Richard

Rusty-Gunn · Dec 05, 2008, 04:46 PM

Wow. Nice build you got here. Good luck on the maiden flight.

yardboz1 · Dec 05, 2008, 06:08 PM

Richard,
Really interesting plane and a great looking build! Wonder if that big ol' rudder will give you any issues? Also, what are your thoughts on elevons only? Undercarriage looks too nice to land on!

Sterling

Nov 24, 2008, 07:57 AM	#1
RJPIoW Parkesflyer Join Date: May 2006 Location: Cowes Isle of Wight UK Posts: 584	36" span Rohr 2-l75 ducted prop plan now with prototype history explained Not sure if this is an edf or a ducted prop project, but for a while Ive been thinking about this rather radical 1970's design as a foamie. This delta winged, shrouded fan plane was built by Rohr as a direct competitor to Cessna's dominance of the small plane market. Financial troubles eleswhere in Rohr meant that it got cancelled before it went into production. From the little Ive found though it appeared to fly well, and now Ive scaled up a 3 view for a 36" span depron version. The wing span resulted from scaling the duct for a suitable prop. I considered making it a KF wing, but in the end Ive gone for simple 6mm plate wing to replace the original symetrical one. So far Ive cut out the wing and much of the basic fusalage shape. Im waiting delivery of the UH HXT28-26-CQ 1300Kv Brushless Outrunner that will be fitted with a 7x4 prop inside the duct and hopefully this will arrive this week and then progress can continue Richard Edit after posting this was the piece that got me intersted in this plane as a foamie http://massflow.archivale.com/2_175.htm Attached Thumbnails the only photo I have been able to find of this unusual plane. 18.2 KB · Views: 347 64.6 KB · Views: 285 91.3 KB · Views: 210 Last edited by RJPIoW; Jan 21, 2009 at 02:07 AM.

Dec 01, 2008, 11:49 AM	#9
RJPIoW Parkesflyer Join Date: May 2006 Location: Cowes Isle of Wight UK Posts: 584	The motor arrived and Ive fitted it. A few photos attached to show progress so far. Hope to have a reasonable plan ready soon. Richard Attached Thumbnails Elevons cut out and 6x1 CF spar fitted to wing 62.7 KB · Views: 187 Motor fitted with firewall then ducted fan cutouts completed 81.1 KB · Views: 186 Fusalage belly pan fitted over balsa spar 55.6 KB · Views: 219 Duct folded and tape stiffners added 77.8 KB · Views: 175 checking prop tip clearance with temp disk fitted 81.8 KB · Views: 221

Dec 05, 2008, 04:51 AM	#10
RJPIoW Parkesflyer Join Date: May 2006 Location: Cowes Isle of Wight UK Posts: 584	More progress - hopefully maiden flight this weekend Richard Attached Thumbnails Fin and Rudder fitted 50.5 KB · Views: 164 LE of cowl braced with depron and skewer 44.6 KB · Views: 212 Elevons now hinged 77.0 KB · Views: 164 50mm wheels with housings ready to glue on 66.2 KB · Views: 202

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Nov 24, 2008, 01:00 PM	#3
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Dec 05, 2008, 12:08 PM	#11
Beemus The Dude Abides Join Date: Sep 2005 Location: Brockport Posts: 309	I am loving the wheel housings! How are you going to keep the duct from warping during flight? I mean, how will you stiffen the foam ring, or are you going to try it as is first?

Dec 05, 2008, 12:40 PM	#12
DRITCH Registered User Join Date: Aug 2006 Location: ST.LOUIS Posts: 1,992	Cool. I asked about this a while back and got "it won't work" from RCG members. I kept at it and found that using an actual fan from a ducted fan or even using 2 props (4blade) made quite a difference in speed. Couldn't find that one prop that would give both speed and thrust. 2 6x3's cut down to 4in spin up nicely and still make a good amount of thrust for low amps. good luck. BTW mine was a MIG 15 with a big ole tube for a fuse.

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Rusty-Gunn My plans are in my blog Join Date: May 2006 Location: Kotzebue, Alaska Posts: 4,462	Wow. Nice build you got here. Good luck on the maiden flight.

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yardboz1 Will do stuff for EPP Join Date: Sep 2007 Location: LaSalle, Illinois Posts: 467	Richard, Really interesting plane and a great looking build! Wonder if that big ol' rudder will give you any issues? Also, what are your thoughts on elevons only? Undercarriage looks too nice to land on! Sterling