Jump to content

Radial Engine Anyone???


irm750
 Share

Recommended Posts

I run up 142kg full fuel on a 130kg 31sqm Gradient Aspen2 DHV2 wing and level flight is at 2800 revs on trim and 3250 revs on full bar for a 98cm scimitar prop. I can get 2hrs from the Konig on a 10L tank with a bit to spare, if I dont fly too high. Mine was the last of the German made engines before Konig went under, so doesn't have the electronic ignition nor in flight recharging which CRE added after Zanzottera had it. Max revs for me is 3700 - I think because the carb is detuned and exhaust manifold is primitive. TTS oil always. No serious maintenance in 12 years except a bing49 carb clean out a few years ago.

There's also a 4 cyl version.

Richard

Link to comment
Share on other sites

These multi-pot radial engines are HOMEMADE - plans for various sizes/configurations can be purchased from http://www.agelessengines.com - a small company in the States run by a chap called Lee Hodgeson.

They are very popular amongst the large scale model flying community.

Plus Points: they are aircooled - so mechanics are a lot more straight forward (compared to water cooled), but they are 4 stroke, so that off-sets (or partly off-sets) any weight advantage of 2 stroke, but with a piston firing every 40degrees or so (in the 9 cylinder example) these engines are going to have great torque graphs.

Questions: not certain about the power/weight advantage - if any, or the fuel consumption - both these figures are great on the full size aero-engine examples (the rationale behind the design and their use in aircraft), but as scaled down model engines, I'm not so sure.

Take the Moki R400 5 cyl Radial Engine (as linked to in a couple posts above) - its a 5cylinder 400cc engine (large by PPG standards) weighing in at 9,5kg's producing 23hp. With all bits 'n pieces added (to include prop), the weight goes up to around 13kg's. The hp figure versus weight and engine capacity, sounds somewhat below what is possible with other engines.

Can anyone comment?

They have a pressurised lubrication system, the mechanical design along with the rpm/hp/torque relationship is designed for direct drive (i.e. prop mounting directly to the crank output shaft) - though some mod work will be needed to drive the prop (in "pusher" configuration).

Theres a lot going for them potentialy, but reliability is going to be down to construction [quality] as they are homemade engines.

Does anyone have hp and fuel consumption figures for the 9 cylinder engine?

Link to comment
Share on other sites

  • 4 years later...

Pagojet

[youtubevideo]

[/youtubevideo]

[youtubevideo]

[/youtubevideo]

I think the normal 1 cyl 2 strokes has the best performance for paramotor but if I would get a radial it would be a 4-stroke like the Moki as the sound and feeling would be the biggest reason to have a radial.

[youtubevideo]

[/youtubevideo]
Link to comment
Share on other sites

Multi cylinder engines work better in larger displacements, when the cylinders are close to optimum size.

The optimum size for a high speed IC engine cylinder seems to be around 350cc. A smaller cylinder has much less capacity for a little less weight, while a larger cylinder has much more capacity for a little more surface area and is more likely to have cooling problems. Aircraft radials have the benefit of 'free' forced air cooling, so the cylinders can be quite large at (3000cc each on a 3500hp 18 cylinder dual radial!)

A single cylinder engine is technically a radial, in that all the cylinders drive a single crank throw. It is the single crank throw which makes the radial design attractive for aviation, giving a short, light crankshaft and case compared to a similar sized inline engine.

All that becomes insignificant when a radial coughs and splutters into life, clearing the cylinders one by one until the crisp crackle of pure engineering porn takes over :P . This is what keeps me in the workshop late in the evenings in the depths of winter.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share



×
×
  • Create New...