# Recent content by Mark Roberts

1. ### Polini Thor 202

I am part of a group that is making its own airframe and we already finished designing it so I think it will be easier to tell if we have room once it's built.
2. ### Polini Thor 202

Thank you for your advice. I think I am comfortable going with a single spark plug and I am going to wait until I finish the fuselage to see if there is enough room to have the pull starter in the cockpit or if it should just be on the outside.
3. ### Polini Thor 202

I have been looking for an engine for an ultralight that I am building and I think that the 202 is the best option. The two concerns I have are that it only has one spark plug and no electric start. I am thinking of running the pull starter to the cabin so that it can be started from inside. I...
4. ### POLINI THOR 250

Thank you all. I will make sure to not run the engine at full power at cruise to extend the life.
5. ### POLINI THOR 250

Thank you there was a lot of useful advice there.
6. ### POLINI THOR 250

I am about to buy a Polini Thor 250 engine for a puller style ultralight. From everything I have seen it seems like the engine should work but does anyone know of any problems with that engine that I overlook. Thanks
7. ### Engine positioning

I am part of the group working on that plane. Our fuselage will fit a person and according to all of our research and simulations will be plenty strong. We are also under the weight requirements for an ultralight. We are determining the center of drag for the engine location. We assume the...
8. ### Engine positioning

We are making a part 103 ultralight. Here is a link to our fuselage design blog post if that will be helpful.
9. ### Hirth f33 pricing

I am not sure if the 202 can work as a pusher but I know the polini thor 250 can. The only downside is that it is a little heavier but it makes more power so I think it will work great. Thank you all for your help with this.
10. ### Engine positioning

I am not sure where the engine should be mounted in relation to the cg and center of drag. I thought the center of thrust should be inline with the cg to not induce any moments but if it is inline with the center of drag it would cancel out the moment created from the drag. Does the center of...
11. ### Hirth f33 pricing

Thank you. Something seemed off about the 3000$one. The site you linked is the one that quoted me$6,635 so I assume that is a good price for them. The other issue I have is that it will take around 13 weeks to get the engine and I was hoping to get it quicker. I am now looking at different...
12. ### Hirth f33 pricing

I am looking into buying a hirth f33 with an electric start, exhaust system, and a reduction drive. A place called PPG Paramotor from Indonesia quoted me \$3110 with shipping. That seems like it is very cheap from what I have seen. Are they trying to scam me or is that the good price for the...