Umran

Hi All,
I would like to share this prototype autostart system for DLE 111cc engine. It was designed and developed by myself as there were challenges from our local RC fliers on their difficulty in starting gasoline engines.

After 1 month designing and another 2 months developing it, i managed to get it all worked-out. With proper involute gear meshing and ratio, a lot of bearings, this system came alive!

Kindly view this system in action during initial testing phase.

Enjoy...

[youtube]http://www.youtube.com/watch?v=2UfxyF2O4Q8[/youtube]

For info, this video was taken today itself.

Thanks for watching.

BadAzzMaxx

Very nice, The warbird people will love it.

Need a little more info like the weight and how it installs.

Milton

jedijody

My Feedback: (1)

Cool!

Umran

The additional weight is roughly 300grams. Small modification required on the engine for installation.

jedijody

My Feedback: (1)

You going to keep it a secret or are you going to show us what you made?

BadAzzMaxx

Will it work on engines other than a DLE

If the cost is not really high I would like to have one just to play with and have some fun.

Milton

DadsToysBG

My Feedback: (35)

sub

MetallicaJunkie

interesting!

Ed Vollmer

My Feedback: (14)

It looks really good. So share it.

Umran

The design alone provides me with a lot more grey hairs... the loading at which this system can take is up to 150cc class twin engine, but with some minor starter motor rating change. In the cross road now, whether to work with DLE engines for production base system, or to produce myself(which is quite costly!)

I will share some photos later...

Valve floater

Amazing!!

MetallicaJunkie

its definitely not something i would want on one of my 3d jobs, but something scale where extra weight upfront is ok, would be nice

krayzc-RCU

My Feedback: (31)

that is 2 kewl 4 school

I love it this would help those guys who love to get on their knees prior to attempting to start the beast....

[8D][8D][8D][8D][8D][8D][8D]

gboulton

My Feedback: (15)

Definitely subscribing to this thread.

av8tor1977

My Feedback: (6)

http://www.hobby-lobby.com/starter_f...ueryId=1226787


AV8TOR

MetallicaJunkie

thats the micro version....... i seriously doubt that the Hoobly lobby version would crank over a dle 111..........but you have a point, that its been done before

jedijody

My Feedback: (1)

Starters, generators, or alternators for our engines, even large ones,is nothing new, http://www.sullivanproducts.com/Prod...xMainFrame.htm

But for a hobbyist to design and test their own system is intriguing, would love to see the nuts and bolts forgrins and giggles.

Umran

Okay guys, some production photos....

gofly2000

My Feedback: (41)

Very clean design. lovely.

Umran

Thanks.

Yes there are few systems that can do this job, but many have a bulky components at the frontal area of the engine. This hampered the cowling installation and everything else... With this in mind, i placed a great emphasis on getting it as small as possible, light as possible, yet it's appearance is basically non existence. And that is the reason why i shoot the video from frontal view of the engine.

Milton,
You asked about the price... in my personal point of view, i consider this quite expensive for now as each individual components needed to be machined one by one. But who knows maybe later some big company or DLE himself would like to mass produce it, then it should be very much cheaper.

To others who are interested, kindly send me PM, then we can discuss about it.

BadAzzMaxx

If someone did mass produce them they would sell very good but it looks like you have to do some maching on the rear of the crank case to make them work.

That is what cought my eye was the fact that it was rear mounted.

Very good job and looking forward to seeing more pic's of how you mounted it.

Milton

marcin-rc

Would you post details here ? I have ROTO 50 TWIN, and was thingikg about this same. To expensive buy org from Lobby.

BarracudaHockey

My Feedback: (11)

That's just cool!!

Scota4570

Where is the Bendix or it's equivelent?

Umran

Milton,
I'm doing some talking with a few manufacturer at this moment... so see how it goes with it, about the installation picture, maybe after the deal is made.

Barracuda,
Thanks.

Marcin,
I saw that ROTO 50 twin config, rear carb design... if there are internal drawing of that engine, i may figure something out for you.



To those who are interested in designing their own starting system, i list down something here which may help,

1. Pressure x Volume = constant(provided the temperature remain constant)
=> P1 x V1 = P2 x V2, where P1 = ambient pressure, V1 = Initial Volume, P2 = End Pressure, V2 = End Volume
=> Using Engine data, (BORE x STROKE) + Squish Volume = V1 (initial volume), where V2 is just the Squish Volume alone, one may determine the final pressure P2, if twin just times 2 of this figure.
=> The torque to overcome by the system = P2 x BORE x 1/2 x Stroke (if you did not times 2 for twin engine above, then the 1/2 here can be omitted)
=> Now to satisfy quick and confirmed cranking of your engine, you may need at least twice this torque for your system(don't forget, as the engine poured with fuel, those piston rings seal better)

2. Depending on typical idle rpm, you may need to crank the engine to at least 10% of this rpm. Say in my case, DLE111 can idle at around 1300rpm, so at least i need 130 cranking rpm.
=> Power required(kW) = [Cranking speed(rpm) x Torque(N.m) x 2 x pie]/60000
=> Find a suitable motor that can provide such power requirements.
=> Look-up the motor data for typical voltage per rpm output.
=> From there you can calculate the step down gear ratio.(based on the input voltage and expected motor rpm, but can at least handle the power required as above)
=> But have to at least add in 10% losses per gear contact, the more number of gears the heavier the losses. So choose the motor as such it can provide higher torque but enough rated power as above. So that we lower the number of gears, yet maintaining the right ratio.

3. Gears
=> The number of teeth vs pitch diameter constitute the gear teeth base surface; based on the material used, this base must be large enough to overcome the shear stress of system.
=> Highest teeth load will be the final drive gear to your engine shaft, this load can be calculated as per, Load = Torque/radius of the pitch diameter of the gear.
=> Shear stress = Load/Base surface of gear teeth, compare this with known data of the material, if it fall within 1.5 times less than ultimate strength, then your gear teeth will hold!

4. Gear shafts and bearings
=> The size of the final gear shaft is critical, even with bearing mounted shaft, side loading amounted to LOAD calculated above will be experienced by this shaft. Check for shearing stress of these shafts(load/shaft correctional area).
=> As above item 3, compare against material data. This process again needed for the bearings(data can be found from bearing manufacturer)

5. Bracket Structure
=> Again depending on material use, the thickness of this bracket can be determine by factoring in the LOAD.


So, all these design approaches that i just mentioned is to ensure you'll have a good and reliable on-board starting system, but if one just choose to do it simply by machining things, no problem also but you can't simply know for sure whether the system you're making will be lasting yet economy enough in terms of it's additional weight.