Testing an Ekranoplan on Water - Will It Work?

Last week, this project took off for the first time. This week, we're pushing the boat out.

Ekranoplans are at home on the water, so it's only right this one meets the lake. Risking making this aircraft even more complex and the project even more difficult to pull off, I decided to slap some floats on the big ground effect vehicle from last week's article to see if it could skim above the surface in ground effect. Did it work? Read on!

Modifications

What has changed since last week? Well, quite a lot of work went into making this aircraft seaworthy. Mods included:

• Waterproofing electronics with a special emphasis on ESCs - check out this video to see how to do this. 
• CG moved forwards to the true centre of lift (over the main wing)
• Added floats - these also act as wing fences to help create that ground effect air bubble. 
• Sealed hull - scraped glue into every crack and seam to illuminate any chance of leakage.
• Paired tilt mechanism to elevator - this was done to make both thrust vectoring and control surfaces work as one to control the craft. The tilt servo was limited through my DX9s travel settings so that it only moved between the neutral position and full ‘up’ position. 

Float Test

To fly, the ekranoplan first had to swim. As the centre of gravity had been shifted far forwards towards the leading edge of the main wings, the aircraft already sat at a pitched forwards attitude whilst on the ground, not helped by slanting floats. Similarly, the plane sat at the same angle whilst on the water. 

Thankfully though, the nose was angled to raise it from the water and the thrust vectoring motors meant that the correct angle could be obtained easily when powering up - crisis averted. Another win was that the plane did appear to be completely waterproof (at the point - an incident later would prove otherwise). 

Getting Airborne

Not wanting to waist much time whilst making the most of the presently still water and wind conditions, the decision was made to power up and attempt a first ‘hop’. Cruising forwards, the machine first accelerated smoothly before plowing into the water. Clearly, it needed more ‘up-elevator’ to counter the high thrust angle of the water.

This proved a little tricky to get used to, but after a few attempts the nose was out and the craft was building speed. 

Launching into the air with that huge wing surface suddenly grabbing the air, the plane took flight - it wasn’t really meant to do that. Surprisingly, it handled well in the air. 

After crossing the lake at a hight of around 3-4ft (completely out of ground effect), I tried to put the thing down. It settled smoothly at first, but soon caught the floats deep into the water. With an almighty splash, the machine stopped dead. Whoops. At least it was back on the water. However, something had gone very wrong. 

Out of Control

Within a few seconds, it was evident that the RC ekranoplan had lost contact with the transmitter with the front motors still spinning. This would have been pretty serious if it were to be airborne, but thankfully it was firmly pressed into the lake thanks to that downward attitude. It continued to move about in circles whilst attempts were made to reconnect the radio. Simultaneously to this problem, the ground effect vehicle was filling up with water, fast. 

The hard landing had not only broken the electronics, it had also broken the hull. The weight of the machine had ruptured one of the folds or glue joints in the floats and main fuselage meaning both were taking on water. It was a race against time, but thankfully the whole project didn’t sink and it slowly drifted back to the shore. 

What Went Wrong

After extensively testing the electronics since the ekranoplan’s ordeal on the water, it seems that a damaged receiver is the most probable explanation for the LOS. Although a failsafe had been set, the forward ESCs were locked with a signal to keep a small amount of power to the forward motors. This could explain why they remained on. 

Assessments

In many ways, it’s a shame that the Ekranoplan project wasn’t a little more successful. However, in hindsight, it can be said that a lot was learned. Probably the biggest lesson was the confirmation that even the failed projects can be enjoyed. Failure isn’t the end of the story, it’s the beginning of new ideas. 

If you have a project you’re working on, make sure to write about it here on www.flitetest.com in the form of an article (like this one), on the FT Forums as a thread post or on the Flite Test Fans Facebook Group. Let’s keep building, experimenting and sharing with others. 

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Article by James Whomsley

Editor of FliteTest.com

Contact: [email protected]

YouTube Channel: www.youtube.com/projectairaviation