Engine mount reinforcements and steering inputs

Today we successfully tried running both the lift engine and the thrust engine simultaneously. Successfully too!

We started with just testing the thrust engine. Bringing it up to full throttle and making sure it was stable with the reinforced engine mounts.

We also tested the rudder action. I am amazed that it seems fully controllable without much load. And in the tests you can definitely feel the difference when adjusting the steering. The steering action is relatively light and seems responsive.

Here's the video of that test:

I actuated the rudders to see if we got good lateral pressure. There was definitely pressure. Hopefully it will be controllable.

And an alternate viewpoint:

The rear was restrained by Michael and Angel, while Christian kept the front from drifting too much. You can see as I try moving the rudder back and forth the craft is trying to move side to side. 

The travel available in the rudder is not symmetric. We calibrated the front such that the stick is centered, however the range of travel available at the stern is not centered so the stick's travel matches it. The mechanism at the back is adjustable with threads so I think I can tune it properly without too much work. Unfortunately though it does require disassembling the rudders to rotate the mounting point along the threads. 

We hovered in and out of the garage successfully as well as repositioning. 

Note getting the kill switches wired in is on the short list.





The hovering is now getting anti-climatic enough that I might consider not filming and editing every moment of it. 

And here's what we did today. 

The main work was to get the tiller mounted in the cockpit and connected to the steering cable. 

Trimming the hinge down to not go too far up the tiller

Is this where you mount a table leg? What side up?

The final tiller solution with the cable mounted on a hinged board and our table leg tiller attached to the hinge.

And the other main work was to reinforce the thrust engine mount. It now has diagonal braces both sideways and forwards. These are bolted into the boards which are glued to the base. So it is much more ridged now. 

Previously if I leaned on it with most of my weight it would visibly deform. Now it does not deform at all. 

Thanks to Michael and Angel for all their help as well as Christian who helped with today's progress and successful testing.  Special thanks to Angel for the in action shots.

And as a final note, I've ordered an important accessory, knee pads...

More bracing for the thrust engine mount and housing

The engine mount worked when we tested it but there were definitely some oscillations which were larger than I'd be happy with overall.

Once turning it off, there are definitely directions in which it will flex when I push hard on it. To take that out I've started adding some bracing.

The first weak point is for and aft support for the fan housing. The top of the fan has a lot of leverage over the small footprint of the housing mount and relies on the plywood to take the load via torsion. To that end I've braced the top of the fan mount forward.

The second weakest direction I identified is lateral movement of the rear of the engine mount. It is currently relying on the plywood bracing at the front of the mount, which is quite rigid, but with 12 inches of leverage the shaking motor can make quite a difference. I secured it with a small diagonal brace, but there's definitely flex in the system. So I'm adding two diagonals which will brace down to the corners of the fan mount, giving direct lateral support just below the engine.

Lastly, the forward thrust of the engine is only taken by the angle brackets making the box for the engine mount. That's going to be the primary loading direction when the engine is running. So I will also run braces forward to transfer the load into the deck via the rear edge of the cockpit.

Here's a timelapse of me securing the fan housing forward and starting to work on the lateral supports. The battery ran out much sooner than I expected.



I used some stainless hinges to secure the top of the fan. I don't need the flexion, but the variable angle bracing is convenient.

The bottom of the braces are through bolts.

The lateral braces, one seen below, pinned but not secured will be through bolted at both ends. I needed to pick up a few longer bolts to properly secure the braces.

Status at the end of the day.

Still todo is also to brace the engine mount forward as well.

More hovering and thrust engine test

Thanks to all the help from Tudor we got in another flight test!

We started out with hovering out of the garage.



Two things were clearly identified from the tests. One is that we have more weight at the back then at the front. Secondly the garage has a defined slope to the left as you enter.

Then we tested the newly mounted thrust engine.



It was great to get the 2nd engine running. We didn't go anywhere since there were several things identified that should be reinforced. And we only had 3 feet of runway ahead of the vehicle.

The engine mount needs a little bit more reinforcement especially torsion around the vertical axis. And unfortunately the screws in one of the newly mounted lifting handles backed out a little bit. They apparently had a little bit of play and were not backed into the epoxy.

And of course the rudder system is not fully functional yet. But it's mostly for a lack of controls now. The whole system at the back should be basically there.

Finally we gently hovered back into the garage.



It's amazing how easily it slides. You can see Tudor's barely pulling on the ropes.

Note about engine manuals

It's been very frustrating finding the appropriate engine manuals.

Briggs and Stratton have nice menus to find your engine based on some part number but that seemed to be focused on integrated designs and I never was able to get the right manual from them.

Eventually I found pdfs of similar models in google searches.

Even then they're not the most useful.

For my future reference it seems that 0.5 quarts for the lift engine and 0.7 quarts for the thrust engine are the appropriate amount of oil.

Thrust engine and rudders

Thanks again to Tudor for all the help.

We started out the day with some additions and reinforcements.

We added a lower rail for mounting the rudders. We added a dashboard panel. And reinforced the engine mount, and glued down a hinge for the steering stick on a backing board.


On our trip to West Marine we were unsuccesful in our search for steering and throttle controls. We did find a steering cable which we picked up. And the other breakthrough we had was finding some clamping oarlocks which make nice bearings for the rudders.



With a brief break for a battery change...

We continued mounting the rudders, including adding posts at the leading edge to tie them together as well as bolting on the end of the steering cable. The combination of the oar locks and some left over T-brackets with some subtle applications of lock washers as spacers of the right radius made the rudders look quite good.

Tudor also rounded off the front of the rudder as well with the sander. We did a tear down and reassembly to clear the airway too.


We ended with a little bit of a cleanup before our next tests...

Thrust engine mounted

With a few more fittings and help from both Christian and Tudor the thrust engine is now mounted and awaiting it's first test tomorrow.

The morning started out with a bit of a setback though. I tried testing our reinforced handles, and the results were a complete failure. Lifting on the handle just tore a handle base plate sized chunk out of the side of the hovercraft.

The results of testing the lift handle.

As a result of this we decided to choose a new handle style, with a larger mounting plate. We found some pull plate handles from commercial doors which seemed to fit the bill and could take advantage of the reinforcement plate we had already installed. (with a little trimming)

After a quick trip for the new handles and some more fittings we replaced the handles and worked toward mounting the engine:




In the video you can see with the screws removed from the rest of the handles, I was able to just pull them off.

After a bit of a break we were able to get the fan and propeller ready to run.



With the fan prepped we focused in on the engine mount.

We significantly improved it by switching to use brackets with a diagnoal piece instead of just the one piece of bent sheet metal.




The oak board for mounting the engine worked way better than I thought. it's quite solid, but still easy to work with.

There were some worries about impingement between the mounting brackets and the through bolts holding the engine mount board to the assembly, because the engine mount needed to be moved to Bthe rear to accomadate the distance to the fan housing. but we were able to get enough spacing to not worry about too little leverage. And really 1 bolt on each side would actually be enough.

The other compromise we found was to add a diagonal brace to the engine mount for lateral stiffness. i had been planning on a full width piece of plywood for the front of the engine mount, but we changed it up to just a diagnoal stringer to allow for increased airflow.

And finally with the engine mounted we mounted the propeller and closed up the fan housing.



At the end you can see us working on filling in the rudder design.

The thrust engine, fan housing and propeller final assembly from the front.

The thrust engine, fan housing and propeller final assembly from the behind

A fun note, this was a 4 gopro battery day. It's great to have easily exchangeable batteries. Otherwise you would have missed a lot of this.

In the course of this day we made a lot of incremental progress and refinements. The fan housing was assembled and disassembled many times. It's frustrating but worth iterating as we see improvements.

It's going to be fun to test the engine tomorrow. We made sure that the collet and propeller mounting is very well secured as we learned is necessary for the lift fan.

Reinforcing lift handles and thrust engine mounting progress

Thanks to Tudor being in town I've been a little bit more active on the project.

We started out by reinforcing the lifting handles as they were making very bad sounds if you started to lift by only one.

We added a poplar plate around the handle to try to distribute the load.

Then we returned to the engine and fan mount. We finished assembling everything and fit checked the fan. After which we glued and screwed down the base parts.

Part 1:



Part 2:



One thing to note is that of the 9 toggle bolts we used 2 failed to twist the toggle correctly. So we had to reverse course and remove the whole assembly to replace the toggles.

Thrust Engine Mount Partial Assembly

I started assembling the thrust engine mount today. I didn't get a lot done since I got distracted by other things when I needed to get more screws. But I'm confident between the brackets and some plywood attached to the sides the engine mount will be quite solid.

Here's the time-lapse of what I did today.