Coccinellida

This is my most unconventional model to date. The model was inspired by an article on jetex.org about a model of so called coleopter.
Unfortunately, no Jetex or similar motors were available. So I decided to adapt the configuration for use of available conventional A-size motors.



Apart from the wing the main feature of the model is a placement of the motor. It sits above the model CG and its exhaust channelled through so called an augmentor tube made of aluminium foil I cut from a barbecue tray. Recovery is by a small mylar parachute packed into the motor tube above the motor.



(Note the diagram does not show the final version of the nose cone design as well as 8 air intake ports)

The following video illustrates the model design and the build process.
[YOUTUBE]GMfoeMh8T4s[/YOUTUBE]

The model's mass excluding the parachute and the motor is 40 grams. It is a bit heavier than I wanted it to be, but it should be OK for A10 motor.

With such a long tube for the exhaust do you think you will get a Krushnic Effect? Maybe some hibachi effects as well? I guess the proof will be in the flight! Good Luck and it looks marvelous!

Daddyisabar said:

With such a long tube for the exhaust do you think you will get a Krushnic Effect? Maybe some hibachi effects as well? I guess the proof will be in the flight! Good Luck and it looks marvelous!

Click to expand...

That's a good point - if that's where the motor is going. I can't quite tell from the diagrams if the motor is going up inside the tube or not. If it is going up inside a tube it may not work too well plus most 13mm tubes are rather...ahem...flammable.

Both effects are possible of course. The first flight will tell. However, there are eight 5mm air intake ports above the exhost tube. The diagram does not show them, but they can been on on the photo I have added to the top post.

I hope it flies well, I would love to have a design where the motor goes up front and you can make cool looking birds with hidden internal motors. Please give us a full flight report so we Yanks can use that wonderful British technology, just like we did on the jet engine and radar!

I promise you'll know the outcome. I did a static test with A-size motors firing through the very same exhaust pipe. All went well and I don't expect any issues assuming CG is at the right place and recovery works.

Pop it up with an A10 with no stinking, performance robbing nose weight. That will be cool. Then it is time to do one in 18mm, then 24mm and so on and so on ...

Reminds me of some of the old Estes "augmented thrust" designs like the "Augie II."

I've finally had a chance to launch the model. Unfortunately the only motor I had available was A3-4T. Taking into account the model size and mass (50g) 4 seconds delay was too long. Luckily grass was tall and soft enough. Here is the video:

[video=youtube_share;DP7qDuDk4_Y]https://youtu.be/DP7qDuDk4_Y[/video]

On the good side is that all systems worked as expected (just a bit at the wrong time). The model is stable, there is no damage to the augmentor tube.

Very nice even in the wind. A wee bit more power would do wonders! KUTGW!

After the successful test reported above I've started working on the up-scaled version. Here is a couple of progress shots:

COOL!

JNUK said:

After the successful test reported above I've started working on the up-scaled version. Here is a couple of progress shots:

View attachment 129297

View attachment 129298

Click to expand...

And here I always thought the Brits just fly their model rockets with motors they can carry in the shirt pockets! But I still see colour photography has not made it across the pond. At least you guys have preserved those vintage fuel trucks the Yanks brought over during the last big war.:smile:

Daddyisabar said:

But I still see colour photography has not made it across the pond.

Click to expand...

Well, it has in fact my American friend


However, I have to confess I'm following French in this one - LINK

JNUK said:

Well, it has in fact my American friend
View attachment 129305

However, I have to confess I'm following French in this one - LINK

Click to expand...

Very futuristic being in colour and all. Steal the casters off your chair at work, cut the top and bottom off a beer keg, take a trip to the nearest Junk Yard that has a stack of old vacuum cleaner parts and you will be set to fly it on the biggest motor you can find. VTOL with Retro Euro style!