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Jul 08, 2021, 11:09 AM
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Originally Posted by tomtom001
The French tried this to some good effect! I believe it only run for a few years however, rising fuel costs etc.

Yes many of the early skirtless craft were segmented in sections, it was more for stability creating individual sections underneath.
I understand what you're trying to achieve, perhaps a number of individual round peripheral jets under the craft? similar to seaspeed but skirtless.
Yep, that's the thing.
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Aug 07, 2021, 06:56 AM
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G'day Tom,
I have been impressed by your models and I've been producing both your hovercraft so far but haven't got them assembled yet. The BHCN001 has me stumped at the moment. I'm making good progress with this CC2 though. The servos are a thorn at the moment I have a pair of Dynam micro servos which are smaller than 9g ones but seem to be too large for the servo bay.
One thing that I am curious about is how you settled on the dimensions for the "Valves"? Were these scaled from drawing and pictures or arrived at through experimentation and are as a result the smallest practicable to achieve steering authority? I was thinking if smallest wasn't the case I might try making some that are narrower so as to not let as mush air escape when open and possibly increase the speed through the valve. Then the next question would be would and increase of directional air velocity actually cause a low pressure zones under the hull? I use Onshape for my CAD btw.
Aug 16, 2021, 03:04 PM
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Originally Posted by hoverhead047 View Post
G'day Tom,
I have been impressed by your models and I've been producing both your hovercraft so far but haven't got them assembled yet. The BHCN001 has me stumped at the moment. I'm making good progress with this CC2 though. The servos are a thorn at the moment I have a pair of Dynam micro servos which are smaller than 9g ones but seem to be too large for the servo bay.
One thing that I am curious about is how you settled on the dimensions for the "Valves"? Were these scaled from drawing and pictures or arrived at through experimentation and are as a result the smallest practicable to achieve steering authority? I was thinking if smallest wasn't the case I might try making some that are narrower so as to not let as mush air escape when open and possibly increase the speed through the valve. Then the next question would be would and increase of directional air velocity actually cause a low pressure zones under the hull? I use Onshape for my CAD btw.
Hello, first of all thankyou and sorry for the late reply I have been on holiday!

So both the srn1 and the cc2 are actually different from the full size craft in terms of final control. With the srn1 the reason was the small scale, it was not feasible to achieve what the full size craft used and that is a sliding valve at the beginning of each of the thrust tubes just after the 'T' split. The slightly rounded 'T' split on the real craft seams to have very little inside of it apart from some static flow direction vanes. Instead I designed a 3 way valve that fitted inside that 'T' this gave me the same control, less moving parts, was easier to connect to a servo and was much easier to print while not impacting on the aesthetics.

The cc2 on the other hand really had me thinking! At first I tried to copy the control mechanism of the full sized craft as close as possible using text, photos and drawings. The full sized craft uses one full peripheral jet and two rows of jets running full length from front to back, these two full length jets done two main things, they gave the craft stability and also control. The two long jets had many directional control vanes along there lengths so when linked and moved as one they gave the craft its control and tank like movement. Unfortunately even with exaggerating the vanes at 8mm long at this size they did not give the control needed for a practical RC model, not only that it was a nightmare to try to build with so many linkages and pivots.

The two full length jets were kept for some scale but more importantly stability. Next I tried using two, 3 way valves similar to the srn1 but inside the pressured hull, one on each side. Running two ducts from each valve, still inside the hull, to the outer corners exiting at a 45* under the craft inside the curtain. This was better but still not enough! Ultimately it was a too restrictive set up.

After much thinking I came up with the 4 directional shutter valves. They each use 3 much larger vanes that can effectively change the direction of the air, be completely shut off and are set off centre meaning about 35% of the vanes surface is trying to open it reducing strain on the connecting rod and servo. This worked a treat, and believe it or not is actually much easier to build than the first attempt. With a scale sized peripheral jet and stability jets it basically flew, but was not stable, to much lift and not enough pressure/airspeed for the valves to give good control. Reducing the jets width gave good usable hover height and made the valves even more effective. I'm sure I took photos and can find them on my old phone if your interested.

The valves were made to be as large as possible to give as much control as possible and the jet widths tuned for a balance of hover height and valve effectiveness.
I understand what you mean about a low pressure spot, in theory there is a spot of low pressure behind that 45* exhaust, but worst case it will just slightly chance the direction of the thrust more horizontal to the hull plane but without real test equipment (that I cant use anyway) I cant say for sure but I don't think it will impact on it much, the exhaust is so close to the rear end of the model and the air is slightly expanding.
With all this waffle please do feel free to try any alterations you like!
Last edited by tomtom001; Aug 16, 2021 at 03:14 PM.
Aug 26, 2021, 05:50 AM
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Thanks Tom for that interesting explanation. I had been considering tinkering with the valve widths prior to asking my question. I was interested in not repeating something that might have already been established as nfg.
I may however tinker with the valve frames to make them a little easier for me to install in the hull.
Aug 29, 2021, 02:45 AM
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Bonjour


Bonjour voila le debut fait avec une ender 3 sans probleme cool
Oct 08, 2021, 09:30 AM
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thank you for the jig just started printing this hovercraft it will be a big help
Oct 24, 2021, 12:08 PM
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Coucou
avez vous les lien sur ali pour l electronique svp
bonne semaine a vous
Nov 23, 2021, 05:39 PM
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Quote:
Originally Posted by Franck 84
Coucou
avez vous les lien sur ali pour l electronique svp
bonne semaine a vous

Bonjour! build is looking good please have a look at the first post on this thread, there are some links to parts, descriptions and pictures of the layout


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