Rohr 2-173

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vhhjr

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I read a flight report and this aircraft apparently flew quite well. Unfortunately, if I remember correctly, Rohr decided not to get into the airplane business and destroyed the air frame to avoid liability issues. Sad, but we all know the lawyers prevail.
 

Riggerrob

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Wow, look at that step/droop in the leading edge just outboard of the main gear!
That sort of dogs' tooth notch is quite common on swept wings because it reduces spanwise airflow along the leading edge. It reduces the risk of a wing root stall continuing all the way out to wing tips. Because wing tips are behind the centre of gravity, they produce a positive pitching moment (nose down) that helps with stall recovery.
Early Mig fighter jets solved problems with pre-mature tip stall by installing wing fences.
Many delta wing fighters (e.g. Mirage) have dogs' teeth.
Burt Rutan solved the problem with tiny pylons hanging below the rear/main leading edges of his Long Eze canard.
Velocity added similar tiny pylons to rear/main wings of their Rutan-like canard after a prototype crashed in a flat, stalled attitude.
 

Riggerrob

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Dear moderators,
Please merge this thread with the other thread about small deltas: Dyke Delta, Delta Kitten, Facetmobile, Hustler, Verhees Delta, etc.
 

Hephaestus

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If it was to be merged there's a few already on the Rohr 2-175

This would be an absolute winner as a kit :)
 

cheapracer

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Dear moderators,
Please merge this thread with the other thread about small deltas: Dyke Delta, Delta Kitten, Facetmobile, Hustler, Verhees Delta, etc.
No way, this is a unique, stand alone aircraft. It shares very little in common with those others, other than being a delta planform.

How about we throw all 3 axis aircraft in together instead? Yeah, thought so.


This would be an absolute winner as a kit :)

One very unique feature, is that the fan was designed to use engines spinning at 4000 rpm. That opens the door for a large range of today's automotive engines direct drive (read cheap) that weren't available in the early 1970s.


I have a simple 3D of the Rohr, and a few of my own 'easy to construct' iterations...

Roar 2.jpg

Roar 1.jpg

I have also found Don Westergren, part designer and test pilot of it, hoping to ask him some questions.
 

vhhjr

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This looks like the "Facetmobile" version of the Rohr. Aerodynamically, it's petty much a flying wing as there's no horizontal stabilizer. It will be interesting to hear what Westergren has to say about the aircraft.
 

Hephaestus

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One very unique feature, is that the fan was designed to use engines spinning at 4000 rpm. That opens the door for a large range of today's automotive engines direct drive (read cheap) that weren't available in the early 1970s.


I have a simple 3D of the Rohr, and a few of my own 'easy to construct' iterations...

View attachment 92902

View attachment 92901

I have also found Don Westergren, part designer and test pilot of it, hoping to ask him some questions.
It's one of my favorite aircraft. It looks modern. The tandem would be awesome as long as you kick up the rear seat a smidge for visibility.

A single seat with a Honda would be pretty quick and easy to build it would appear.

I've been trying to get my hands on the for Rohr book for a while. Don W is over on rcgroups if I recall (there is a foamie version there and he weighed in on some of his impressions of the original)

Don't forget to check out the float plane tests.
 

Hephaestus

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? Don't understand.
There were models tested with skis in floatplane style. No joke.


Early in the program somebody realized that the plane was capable of floating on its sealed, foam-filled wing. Tests with scale models showed that the airplane could take-off and land on water with the help of hydro-skis. This opened up the possibility of snow landings as well. With retractable skis, the Two-l75 would certainly have had the cleanest seaplane configuration ever seen.
 

Hephaestus

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Some of the wierd tidbits you get out of reading about the Rohr

Wing was made as green layups of the exterior shell - then they added EPS foam and steamed to get pressure/heat for final cure and to add the core. No spar at all.

I've often eyeballed it as a great scenario for a homebuilder. Cut the wing, and vstab - Rutan style wet layups. A welded steel roll cage structure (go a 40g top fuel dragster style safety cage and engine mount) drop on 2/ 3 molded composite pieces to skin the fuselage. Duct takes a bit more skill to cut but easily done in a CNC Hotwire

The Delta gives it the area so it's like a practical bd5. Other than the approach/flare being 'different' it was apparently quite benign on handling. It was designed to compete with the 150/152...

It could be a quite safe very quick built kit.

Although I really do like the idea of it with a 583/ivoprop as a single seat quick/easy project.
 

Hephaestus

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Only aluminium for me.

Got to figure this one out, worth doing as it solves the engine issue, and that's half the plane.
To me aluminum just makes the parts count and build time soar...

Not volunteering - but it would be interesting to work out the design as 'open source' - work out the details/loads - aluminum, composite and wood version of the same basic airframe. Builders could pick and choose which version they preferred - but keeping some of the oddball pieces backwards compatible - like the duct, the cowling, canopy & frame etc.
 

cheapracer

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To me aluminum just makes the parts count and build time soar...
Well I am proving at the moment that's no where near as bad as some imagine, and I can't change that I am comfortable with metals, and that everything for metal working is within a stone's throw from me.

It would appear to be a matter of fact that Americans, i.e. the world's largest market, are most comfortable with metal kit planes as well.
 
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