Verhees Delta brain fart

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cluttonfred

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Wow, I like wierd aircraft and I still think that's one of the ugliest things I have ever seen. ;-p From the size of the prop, I suspect that they were trying to get near-VTOL performance. Despite the aesthetics, I'd love to learn more.

In answer to your "high wing" + "low aspect ratio" I submit this:

Not a delta wing, but certainly thinking outside the box on low aspect ratio and visibility....

Wonder if it ever flew. I know it got up to doing taxi tests...

~Bill
 

Head in the clouds

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With flaps (like the one big rear flap on the V-173) the incidence for take-off and landing can be brought down to something reasonable for better visibility and shorter landing gear.
Flaps could be used on a flying wing that is swept (like the Northrop or Horten) where the flap would be at or close to the aerodynamic centre, but wouldn't work on a delta or Arups or the V-173 because of the pitching moment they would produce. I think that large 'flap' that you mention on the aft centre of the V-173 is an elevator rather than a flap.

I think the only way a flap could be employed on a delta would be if it's pitching moment were to be offset by having a canard and deflecting the canard control surfaces downward when deploying the flap and cancelling the pitching effect that way. It could well have merit in obtaining higher lift from a delta planform without the high drag associated with high alpha, and the associated risk of getting behind the drag/power curve during an aborted landing and go-around.
 

Topaz

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berridos

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Resuming...we have slats on the outer two thirds of the wing, flaps on the inner third with pitch compensated by the slats. Two small vertical stabilizers at the tips of the wings (no interference drag and endplate effect) A small bubble canopy at the front from which canards hang with two engines on every tip of the canards. The canards in clean air and the corresponding thrust line allow for active pitch compensation. Looks like a compacted small AR horten with canards.
 

Head in the clouds

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Resuming...we have slats on the outer two thirds of the wing, flaps on the inner third with pitch compensated by the slats. Two small vertical stabilizers at the tips of the wings (no interference drag and endplate effect) A small bubble canopy at the front from which canards hang with two engines on every tip of the canards. The canards in clean air and the corresponding thrust line allow for active pitch compensation. Looks like a compacted small AR horten with canards.
If your slats are outboard they aren't going to be very far, longitudinally, from your flaps due to the leading edge sweep, so they won't provide the pitching offset you seek. In any case, do slats actually provide lift at their location or do they increase the total lift of the wing at the mainplane's aerodynamic centre by maintaining attached flow over the mainplane at higher alpha?

I think your pitching compensation will still need to be provided by the canard rather than the slats. By your comment about the 'corresponding thrustline' I assume you're planning an all-flying canard?

You're saying it would look like a small AR Horten with canards, so are you really tending toward a flying wing rather than a delta? If so then the vortex lift discussion is irrelevant and you would most likely benefit from embedded slots rather than slats - shown at the beginning of this Northrop flying wing video and at 1:15

[video=youtube;2eZjIx_ViOA]https://www.youtube.com/watch?v=2eZjIx_ViOA[/video]
 
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bmcj

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This is not germain to the topic at hand, but I have to ask... what is going on with the bottom surface and leading edge of the right wing here?

426820.jpg
 

Head in the clouds

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This is not germain to the topic at hand, but I have to ask... what is going on with the bottom surface and leading edge of the right wing here?

View attachment 26912
Hmmm - having a bad 'air day?

Reflections?

I thought they were ply covered but is this the single-seater and fabric covered? Looking at the paint stripe on the port wing it seems to be affecting both wings, whatever it is ...
 

Doggzilla

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Cool Design. Imagine the design with the pilot sitting near the front in a transparent bubble. The problem I see with the cruciform tail with engines is that the horizontal stab and engines would be total blanketed at steep descent at low speed. Dont you think so? Or would the sucktion of the rear engines contribute to reattach the air flow? Pretty complicated to surpass Verhees reasoning.
One of the beauties for me of the Verhees delta is the compactness of the design. I would minimize the nose.
A Drawback of locating the pilot in the front and the engines in the back would be the inertia of the design. Could make stability unpleasant.

Sooner or later I will need to get my hands on the plans of the design
If you move the pilot forward, it brings the CG forward and it needs to be countered by moving components backwards.

And the VD is simply average... its efficiency per pound is about equal to a Cessna 172... so its not bad, but not good either. It also has some handling issues you can read about in pilot reports....

I think we have a topic here about why flying wings end up being less efficient than sailplanes... All sorts of issues that need to be overcome.
 

Himat

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Hi Everybody

View attachment 26762

I was thinking on a Verhees delta with this engine setup For example using two AIxro XR50 wanker, sorry wankel engines.
To make the idea even more stupid the engine support arm fairings could act as canards rotating around around a boom.
Makes the thrustline offset the design unfeasible on a delta due to the pitching moments introduced by that offset?
I bet the answer is yes. Otherwise the concept would have several really exciting benefits.
I do think the RC model airplane manufacturer already have designed something with the look:

DeltaRay.jpg

Horizon Hobby Delta Ray
 

berridos

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I exchanged some emails with Mr verhees. He is definitly not willing to sell any plans on his ddesign and the two seat version is at the very beginning and progressing slowly due to lack of time.
 

berridos

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He didnt answer to that question. I told him that he was a genius, one of the most brilliant thinkers of the century, but he gave no reply after i insisted on getting the plans. If there are other people interested in the plans we could ask for a bulk order. However due to my personal liquidity situation I wont pay more than 400euros for a set.
An alternatuve is to design such a concept on ourselves. Anybody can propose literature on the design features of deltas?
 

Himat

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Nice concept. I'd probably not make it thrust vectoring but the idea of mounting the engines on the tips of a canard/strake is interesting. Using two engines/props might allow you to run them direct drive and still be able to get enough static thrust. And with small diameters the props' pitch could be set for the high cruise that a delta is ideal for.

I think the configuration has merit and is worth investigation. My only reservation at this stage would be whether the prop slipstream would wipe out the high alpha l/e vortex or perhaps you'd need to have contra-rotating props and be able to use the slipstream to drive/trigger/augment the l/e vortex? Or maybe the prop-blast affected area would be sufficiently inboard only and the l/e vortex could develop outboard of that - maybe have an ogival + double-delta planform just like my avatar so that it would trigger outboard first? The 'blown' canard would have lots of authority and allow a reduced amount of up elevator/reflex and so the vortex lift might not be so necessary for low speed flight.
With a blown canard I do see one thing that have to be investigated, and that is stability. Without “artificial” stabilisation by a FBW system, canard airplanes are usually designed to make the canard stall first and the main wing reach zero lift first. This is to design safe handling properties. How does this work with a “blown” canard?

Still, the idea might be a possible way to design a light plane around two lightweight direct drive engines. (I do see the picture of a microlight Viggen with an engine pod on each canard tip.)
 

Head in the clouds

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With a blown canard I do see one thing that have to be investigated, and that is stability. Without “artificial” stabilisation by a FBW system, canard airplanes are usually designed to make the canard stall first and the main wing reach zero lift first. This is to design safe handling properties. How does this work with a “blown” canard?

Still, the idea might be a possible way to design a light plane around two lightweight direct drive engines. (I do see the picture of a microlight Viggen with an engine pod on each canard tip.)
Yes, direct drive would be a great benefit in this configuration, allowing for higher speeds and small prop diameter/shorter landing gear. It's still rattling around in my head ... I think the whole canard thing might need a different approach, perhaps it would be more of a strake than a high aspect canard, with control surfaces on the trailing edges. As you say, the problems with configuring the canard stall and zero lift of the mainplane would be a problem if it was a pure canard but it would be essential to take into account the conditions of one or both engines failed so the unblown canard or idling prop blanketing must still not prevent sufficient roundout for normal landing. Therefore the available elevon pitch authority must still be significant. The use of the combined canard/elevon concept should probably be considered as a way to reduce control surface deflection for normal powered landings but a deadstick landing might mean a necessary acceptance of reduced CL due to greater elevon deflection, therefore need a longer landing ground. This concept might be beneficial for short field landings with power.

Or something like that, it's getting late after a long day, more thoughts tomorrow.
 

autoreply

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He didnt answer to that question. I told him that he was a genius, one of the most brilliant thinkers of the century, but he gave no reply after i insisted on getting the plans. If there are other people interested in the plans we could ask for a bulk order. However due to my personal liquidity situation I wont pay more than 400euros for a set.
Didn't see him at Sanicole this year. The 2-seater is definitely out now; the builder that originally was to build it passed away a couple of weeks ago (testflight of an electric Cri-Cri)
An alternatuve is to design such a concept on ourselves. Anybody can propose literature on the design features of deltas?
When you keep sweep modest (30-40 degrees max?), they're not that different from any other plane and you can use all the usual equations. Once you get into LERX, slot effects, like with canard/big deltas etc, you're far into CFD/ wind tunnel territory.

Something like the Atlantica bwb might be interesting. Direct drive, compact, fairly straightforward. In essence nothing more than a Long-EZ with the wing swept and moved forward a lot and pitch control on the wings.
 

cluttonfred

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Try to dig up some test data or other details of the Lippisch DM-1 proof-of-concept glider test flown in Austria and the USA at the end of WWII. With a modest gross weight of a little over 1,000 lbs on a generous wing area of over 200 sq ft , it was actually quite squarely in two-seat microlight aircraft territory. With a conventional canopy and fin/rudder, fixed gear and a Rotax 912 it would make a light aircraft that would certainly get noticed on the ramp.

DM1-3view.jpg DM-1.jpg 2539688294_f414f243f0.jpg
 

Himat

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Once you get into LERX, slot effects, like with canard/big deltas etc, you're far into CFD/ wind tunnel territory.
Or full scale RC?
Price/time might be similar or less than a lot of CFD/wind tunnel work?
If sucessful you can fly the finished airplane after testing.
If not you are witnessing the crash from a more favorable position.
 
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